Journal articles: 'LHC ATLAS Luminosity Cross Section'

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Mandrik, Petr. "Top FCNC searches at HL-LHC with the CMS experiment." EPJ Web of Conferences 191 (2018): 02009. http://dx.doi.org/10.1051/epjconf/201819102009.

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The Large Hadron Collider is the world’s largest and highest centerof- mass energy particle accelerator. During the Phase I operation it is expected that the LHC operated at a centre-of-mass energy of 13 TeV will deliver to the CMS experiment total integrated luminosity of ~300 fb-1 till 2023. The High Luminosity LHC upgrade is expected to run at a centre-of-mass energy of 14 TeV and will allow ATLAS and CMS to collect integrated luminosities of the order of 300 fb-1 per year, and up to 3000 fb-1 during the HL-LHC projected lifetime of ten years. The large expected integrated luminosity enables the exploration of the multi-TeV scale by searches for particles with high masses as well as by investigation of processes with very low cross sections such as Flavor-Change Neutral Current interactions in top quark sector. In this report we present a proposal for the top quark FCNC searches at HL-LHC based on Monte-Carlo simulation of the upgraded CMS detector.

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Schott, Matthias, and Junjie Zhu. "Diboson production in proton–proton collisions at $\sqrt{s} = 7~{\rm TeV}$." International Journal of Modern Physics A 29, no. 26 (October 16, 2014): 1430053. http://dx.doi.org/10.1142/s0217751x14300531.

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This review summarizes results on the production cross-section measurements of electroweak boson pairs (WW, WZ, ZZ, Wγ and Zγ) at the Large Hadron Collider (LHC) in pp collisions at a center-of-mass energy of [Formula: see text]. The two general-purpose detectors at the LHC, ATLAS and CMS recorded an integrated luminosity of ≈5 fb -1 in 2011, which offered the possibility to study the properties of diboson production to high precision. These measurements test predictions of the Standard Model (SM) in a new energy regime and are crucial for the understanding and the measurement of the SM Higgs boson and other new particles. In this review, special emphasis is drawn on the combination of results from both experiments and a common interpretation with respect to state-of-the-art SM predictions.

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Yap, Yee Chinn. "Recent observation and measurements of diboson processes from the ATLAS experiment." Modern Physics Letters A 35, no. 28 (June 30, 2020): 2030013. http://dx.doi.org/10.1142/s021773232030013x.

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This review covers results at a centre-of-mass energy of [Formula: see text] TeV from the ATLAS experiment that have been published, or submitted for publication, up to April 2020. It summarizes results on the inclusive production cross-section measurements of boson pairs and of the electroweak production of diboson in association with two jets. The measurements either use the full integrated luminosity of 139 fb[Formula: see text] collected by the ATLAS detector at the LHC from 2015 to 2018, or a partial dataset of 36 fb[Formula: see text]. The inclusive production rates of diboson are studied to high precision. These measurements provide stringent tests of the electroweak sector of the Standard Model and allow search for new physics via anomalous triple and quartic gauge boson couplings.

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Belyaev, Nikita. "Measurement of cross sections and couplings of the Higgs Boson in bosonic decay channels with the ATLAS detector." EPJ Web of Conferences 182 (2018): 02013. http://dx.doi.org/10.1051/epjconf/201818202013.

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After the discovery of the Higgs boson, the measurement of its properties are of particular importance. In this paper, measurement of the cross sections and couplings of the Higgs boson in bosonic decay channels with the ATLAS detector are presented. Previous measurements of the spin and parity of this new particle, as well as the investigation of its couplings to other SM particles, revealed no significant deviations from the corresponding predictions for the Standard Model Higgs boson. In the years 2015-2017, the centre-of-mass energy √s and the integrated luminosity of the Large Hadron Collider was increased up to 13 TeV and 36.1 fb-1, respectively. With this improvements of the LHC, the properties of recently discovered Higgs boson can be studied in more details. In this paper, latest updates on cross sections and couplings analyses of the Higgs Boson are presented. The discussion will focus on the recent results obtained by the ATLAS collaboration in γγ and 4l Higgs boson decay channels as well as their combination.

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Schwienhorst, Reinhard. "Top cross-sections and single top." International Journal of Modern Physics: Conference Series 31 (January 2014): 1460277. http://dx.doi.org/10.1142/s2010194514602774.

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This paper summarizes top quark cross-section measurements at the Tevatron and the LHC. Top quark pair production cross-sections have been measured in all decay modes by the ATLAS and CMS collaborations at the LHC and by the CDF and D0 collaborations at the Tevatron. Single top quark production has been observed at both the Tevatron and the LHC. The t-channel and associated Wt production modes have been observed at the LHC and evidence for s-channel production has been reported by the Tevatron collaborations.

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MANDELLI, LUCIANO. "THE ATLAS ELECTROMAGNETIC CALORIMETERS: FEATURES AND PERFORMANCE." International Journal of Modern Physics A 25, no. 09 (April 10, 2010): 1739–60. http://dx.doi.org/10.1142/s0217751x10049323.

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In this paper it is shown how a sampling electromagnetic calorimeter based on the liquid argon technique satisfies the very demanding requirements of an experiment at the LHC. Section 2 discusses, using a simplified model, the performance that can be achieved in terms of response time, energy resolution and transverse granularity. Section 3 describes how the calorimeters are realized in ATLAS, their segmentation and how from the readout pulses the energy deposited in the calorimeter is computed. The motivations of a presampler detector in front of the calorimeter are also discussed. Section 4 describes how the energy, position and direction of an electron and a photon are computed. Finally, Sec. 5 briefly illustrates the rejection power of the calorimeter against the hadrons and mentions how a Higgs boson signal in the γγ channel can already be detected with a luminosity of 10 fb-1.

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Yin, Hang. "Electroweak measurements from W, Z and photon final states." International Journal of Modern Physics: Conference Series 31 (January 2014): 1460276. http://dx.doi.org/10.1142/s2010194514602762.

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We present the most recent precision electroweak measurements of single W and Z boson cross section and properties from the LHC and Tevatron colliders, analyzing data collected by ATLAS, CDF, CMS, D0, and LHCb detectors. The results include the measurement of the single W and Z boson cross section at LHC, the differential cross section measurements, the measurement of W boson mass, the measurement of W and Z charge asymmetry. These measurements provide precision tests on the electroweak theory, high order predictions and the information can be used to constraint parton distribution functions.

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Hou, Jin-Xin, Chong-Xing Yue, and Yu-Chen Guo. "Search for light gauge boson Zμτ via tt̄h1 production at LHC." International Journal of Modern Physics A 33, no. 21 (July 30, 2018): 1850124. http://dx.doi.org/10.1142/s0217751x18501245.

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We consider the production of the new gauge boson [Formula: see text] predicted by the [Formula: see text] model via SM-like Higgs boson [Formula: see text] decaying in the [Formula: see text] production at LHC. Considering the current constraints on the relevant free parameters, we calculate its production cross-section and further investigate the possibility of detecting [Formula: see text] through the process [Formula: see text] at LHC. We find that [Formula: see text] might be detected via this process at LHC with high integrated luminosity.

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SMIRNOV, A. D., and YU S. ZAITSEV. "ON A POSSIBLE MANIFESTATION OF THE FOUR-COLOR SYMMETRY Z' BOSON IN μ+μ- EVENTS AT THE LHC." Modern Physics Letters A 24, no. 15 (May 20, 2009): 1199–207. http://dx.doi.org/10.1142/s0217732309030606.

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The cross section of the μ+μ- pair production in pp-collisions at the LHC is calculated with account of the Z' boson induced by the minimal four-color quark–lepton symmetry (MQLS). The μ+μ- invariant mass spectrum with account of the MQLS Z' boson is analyzed in dependence on the Z' mass. The mass region for the MQLS Z' boson observable at the LHC is found in dependence on the significance and on the integrated luminosity.

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Mariotti, Chiara. "The Story of a Discovery: How we found the long-sought-after Higgs Boson." Europhysics News 50, no. 5-6 (September 2019): 24–28. http://dx.doi.org/10.1051/epn/2019502.

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The Higgs boson has been discovered in 2012 by the ATLAS and CMS experiments at the LHC, 50 years after its prediction. The scientific and human adventure of this discovery will be summarized in this article, going back to the search at LEP and to the foundation of the LHC Higgs Cross Section working group.

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Theveneaux-Pelzer, Timothée. "Top quark pair production cross section using the ATLAS detector at the LHC." Nuclear and Particle Physics Proceedings 273-275 (April 2016): 2206–11. http://dx.doi.org/10.1016/j.nuclphysbps.2015.09.359.

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Medina, L., R. Tomás, G. Arduini, and M. Napsuciale. "Assessment of the performance of High-Luminosity LHC operational scenarios: integrated luminosity and effective pile-up density." Canadian Journal of Physics 97, no. 5 (May 2019): 498–508. http://dx.doi.org/10.1139/cjp-2018-0291.

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The High-Luminosity Large Hadron Collider (HL-LHC) experiments will operate at unprecedented levels of event pile-up from proton–proton collisions at 14 TeV centre-of-mass energy. In this paper, we study the performance of the baseline and a series of alternative scenarios in terms of the delivered integrated luminosity and its quality (pile-up density). A new figure-of-merit is introduced, the effective pile-up density, a concept that reflects the expected detector efficiency in the reconstruction of event vertices for a given operational scenario, acting as a link between the machine and experimental sides. Alternative scenarios have been proposed either to improve the baseline performance or to provide operational schemes in the case of particular limitations. Simulations of the evolution of their optimum fills with the latest set of parameters of the HL-LHC are performed with β*-levelling, and the results are discussed in terms of both the integrated luminosity and the effective pile-up density. The crab kissing scheme, a proposed scenario for pile-up density control, is re-evaluated under this new perspective with updated beam and optics parameters. Estimates on the expected integrated luminosity due to the impact of crab cavity noise, full crab crossing, and reduced cross section for burn-off, are also presented.

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ANTCHEV, G., P. ASPELL, I. ATANASSOV, V. AVATI, J. BAECHLER, M. G. BAGLIESI, V. BERARDI, et al. "PERFORMANCE OF THE TOTEM DETECTORS AT THE LHC." International Journal of Modern Physics A 28, no. 31 (December 19, 2013): 1330046. http://dx.doi.org/10.1142/s0217751x13300469.

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The TOTEM Experiment is designed to measure the total proton–proton cross-section with the luminosity-independent method and to study elastic and diffractive pp scattering at the LHC. To achieve optimum forward coverage for charged particles emitted by the pp collisions in the interaction point IP5, two tracking telescopes, T1 and T2, are installed on each side of the IP in the pseudorapidity region 3.1≤|η|≤6.5, and special movable beam-pipe insertions — called Roman Pots (RP) — are placed at distances of ±147 m and ±220 m from IP5. This article describes in detail the working of the TOTEM detector to produce physics results in the first three years of operation and data taking at the LHC.

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FIORE, R., L. JENKOVSZKY, R. ORAVA, E. PREDAZZI, A. PROKUDIN, and O. SELYUGIN. "FORWARD PHYSICS AT THE LHC: ELASTIC SCATTERING." International Journal of Modern Physics A 24, no. 14 (June 10, 2009): 2551–99. http://dx.doi.org/10.1142/s0217751x09044255.

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The following effects in the nearly forward ("soft") region of the LHC are proposed to be investigated: • At small |t| the fine structure of the cone (Pomeron) should be scrutinized: (a) a break of the cone near t ≈ -0.1 GeV 2, due to the two-pion threshold, and required by t-channel unitarity, and (b) possible small-period oscillations between t = 0 and the dip region. • In measuring the elastic pp scattering and total pp cross-section at the LHC, the experimentalists are urged to treat the total cross-section σt, the ratio ρ of real to imaginary part of the forward scattering amplitude, the forward slope B and the luminosity [Formula: see text] as free parameters, and to publish model-independent results on dN/dt. • Of extreme interest are the details of the expected diffraction minimum in the differential cross-section. Its position, expected in the interval 0.4 < -t < 1 GeV 2 at the level of about 10-2 mb · GeV -2–10-1 mb · GeV -2, cannot be predicted unambiguously, and its depth, i.e. the ratio of dσ/dt at the minimum to that at the subsequent maximum (about -t = 5 GeV 2, which is about 5) is of great importance. • The expected slow-down with increasing |t| of the shrinkage of the second cone (beyond the dip-bump), together with the transition from an exponential to a power decrease in -t, will be indicative of the transition from "soft" to "hard" physics. Explicit models are proposed to help in quantifying this transition. • In a number of papers a limiting behavior, or saturation of the black disk limit (BDL), was predicted. This controversial phenomenon shows that the BDL may not be the ultimate limit, instead a transition from shadow to antishadow scattering may by typical of the LHC energy scale.

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Chegwidden, Andrew M. "Single top-quark production cross-section and properties using the ATLAS detector at the LHC." EPJ Web of Conferences 126 (2016): 04011. http://dx.doi.org/10.1051/epjconf/201612604011.

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Kłusek-Gawenda, Mariola. "Recent results for UPC at the LHC." EPJ Web of Conferences 206 (2019): 06002. http://dx.doi.org/10.1051/epjconf/201920606002.

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Ultraperipheral heavy ion collisions are a source of photons which can collide with each other producing a pair of particles. This work will be focused on analysis of the light-by-light scattering. Here contribution from fermionic boxes, resonance scattering, VDM-Regge model, two-gluon exchange and pionic background will be compared. Each of these processes dominate at diﬀerent ranges of two-photon invariant masses. Our calculated nuclear cross section is in good agreement with recently measured ATLAS and CMS data. Predictions including ALICE and LHCb experimental cuts for the next run at the LHC will be shown.

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Grafstrom, Per. "Measurement of the total cross-section and soft diffraction by the ATLAS and TOTEM experiments at the LHC." International Journal of Modern Physics A 30, no. 08 (March 18, 2015): 1542007. http://dx.doi.org/10.1142/s0217751x15420075.

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This paper reviews measurements of the total proton–proton cross-section at 7 TeV and 8 TeV by the ATLAS and TOTEM collaboration at the LHC. Similarities and differences between the two experiments are discussed. Some results on soft diffraction are also reviewed. The paper ends with a discussion of prospects and future plans of both experiments.

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Quinto, Michele, Francesco S. Cafagna, Adrian Fiergolski, and Emilio Radicioni. "The TOTEM DAQ based on the Scalable Readout System (SRS)." EPJ Web of Conferences 174 (2018): 07003. http://dx.doi.org/10.1051/epjconf/201817407003.

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The TOTEM (TOTal cross section, Elastic scattering and diffraction dissociation Measurement at the LHC) experiment at LHC, has been designed to measure the total proton-proton cross-section and study the elastic and diffractive scattering at the LHC energies. In order to cope with the increased machine luminosity and the higher statistic required by the extension of the TOTEM physics program, approved for the LHC’s Run Two phase, the previous VME based data acquisition system has been replaced with a new one based on the Scalable Readout System. The system features an aggregated data throughput of 2GB / s towards the online storage system. This makes it possible to sustain a maximum trigger rate of ∼ 24kHz, to be compared with the 1KHz rate of the previous system. The trigger rate is further improved by implementing zero-suppression and second-level hardware algorithms in the Scalable Readout System. The new system fulfils the requirements for an increased efficiency, providing higher bandwidth, and increasing the purity of the data recorded. Moreover full compatibility has been guaranteed with the legacy front-end hardware, as well as with the DAQ interface of the CMS experiment and with the LHC’s Timing, Trigger and Control distribution system. In this contribution we describe in detail the architecture of full system and its performance measured during the commissioning phase at the LHC Interaction Point.

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Ghorbani, Karim, and Parsa Hossein Ghorbani. "The LHC upper bounds for pp → diboson, tt̄ cross-section on fermionic dark matter." International Journal of Modern Physics A 32, no. 22 (August 10, 2017): 1750131. http://dx.doi.org/10.1142/s0217751x17501317.

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The ATLAS report in August 2016 provided an upper limit for the pp[Formula: see text][Formula: see text][Formula: see text]diboson and [Formula: see text] cross-sections. We consider a pseudoscalar-mediated fermionic dark matter together with gluon and photon effective operators interacting with the pseudoscalar. Choosing the resonance mass being [Formula: see text], 750 GeV and 2 TeV, beside the relic density and the invisible Higgs decay constraints we constrain more the space of parameters with the diboson and [Formula: see text] cross-section upper bounds. We finally provide some benchmarks consistent with all the constraints. Having exploited a pseudoscalar mediator, the DM-nucleon cross-section is velocity suppressed so that the model evades easily the bounds put by the future direct detection experiments such as XENON1T.

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Andreev, V. V. "Anomalous constants of three-boson vertices in the process of pair production of W±-bosons in proton collisions at CMS LHC." Proceedings of the National Academy of Sciences of Belarus. Physics and Mathematics Series 57, no. 1 (April 2, 2021): 33–45. http://dx.doi.org/10.29235/1561-2430-2021-57-1-33-45.

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In this paper, we obtained the expected constraints on the anomalous CP-even constants of three-boson interactions on the basis of cross-section for the pair production of W+-bosons in proton-proton collisions. The constraints were obtained for luminosity and the kinematic constraints on the final states typical for the CMS experiment at the Large Hadron Collider at =13 s TeV. One-dimensional and two-dimensional regions of constraints for the anomalous parameters of three-boson interactions were calculated. When calculating the cross-section, the usual approximations of small quark masses and values of the CKM matrix elements were not used. The expected values of the anomalous constants are almost an order of magnitude less than the constraints found at the LEP collider at = 200 s GeV in the reaction e–e+ → W–W+.

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Finelli, Kevin. "Measurements of the production cross-section of top quark pairs using the ATLAS detector at the LHC." EPJ Web of Conferences 60 (2013): 16003. http://dx.doi.org/10.1051/epjconf/20136016003.

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Shu, Jing, and Juan Yepes. "Diboson excess and Z′-predictions via left–right nonlinear Higgs." Modern Physics Letters A 31, no. 40 (December 6, 2016): 1650228. http://dx.doi.org/10.1142/s021773231650228x.

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The excess events reported by the ATLAS collaboration in the WZ-final state, and by the CMS collaboration in the e[Formula: see text]e[Formula: see text]jj, Wh and jj-final states, may be induced by the decays of a heavy boson W[Formula: see text] in the 1.8–2 TeV mass range, here modeled via the larger local group SU(2)L × SU(2)R × U(1)[Formula: see text] in a nonlinear dynamical Higgs scenario. The W[Formula: see text]-production cross-section at the 13 TeV LHC is around 700–1200 fb. This framework also predicts a heavy Z[Formula: see text] boson with a mass of 2.5–4 TeV, and some decay channels testable in the LHC Run II. We determine the cross-section times branching fractions for the dijet, dilepton and top-pair Z[Formula: see text]-decay channels at the 13 TeV LHC around 2.3, 7.1, 70.2 fb, respectively, for M[Formula: see text] = 2.5 TeV, while one/two orders of magnitude smaller for the dijet/dilepton and top-pair modes at M[Formula: see text] = 4 TeV. Nonzero contributions from the effective operators, and the underlying Higgs sector of the model, will induce sizeable enhancement in the W[Formula: see text]W[Formula: see text] and Zh-final states that could be probed in the future LHC Run II.

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CHAKRABORTTY, JOYDEEP, MOUMITA DAS, and SUBHENDRA MOHANTY. "CONSTRAINTS ON TeV SCALE MAJORANA NEUTRINO PHENOMENOLOGY FROM THE VACUUM STABILITY OF THE HIGGS." Modern Physics Letters A 28, no. 11 (April 10, 2013): 1350032. http://dx.doi.org/10.1142/s0217732313500326.

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The vacuum stability condition of the Standard Model (SM) Higgs potential with mass in the range of 124–127 GeV puts an upper bound on the Dirac mass of the neutrinos. We study this constraint with the right-handed neutrino masses up to TeV scale. The heavy neutrinos contribute to ΔL = 2 processes like neutrinoless double beta decay and same-sign-dilepton (SSD) production in the colliders. The vacuum stability criterion also restricts the light-heavy neutrino mixing and constrains the branching ratio (BR) of lepton flavor-violating process, like μ→eγ mediated by the heavy neutrinos. We show that neutrinoless double beta decay with a lifetime ~1025 years can be observed if the lightest heavy neutrino mass is <4.5 TeV. We show that the vacuum stability condition and the experimental bound on μ→e γ together put a constrain on heavy neutrino mass MR>3.3 TeV. Finally we show that the observation of SSDs associated with jets at the LHC needs much larger luminosity than available at present. We have estimated the possible maximum cross-section for this process at the LHC and show that with an integrated luminosity 100 fb-1 it may be possible to observe the SSD signals as long as MR < 400 GeV.

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Bandieramonte, Marilena, John Derek Chapman, Justin Chiu, Heather Gray, and Miha Muskinja. "Multi-threaded simulation for ATLAS: challenges and validation strategy." EPJ Web of Conferences 245 (2020): 02001. http://dx.doi.org/10.1051/epjconf/202024502001.

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Estimations of the CPU resources that will be needed to produce simulated data for the future runs of the ATLAS experiment at the LHC, indicate a compelling need to speed-up the process to reduce the computational time required. While different fast simulation projects are ongoing, full Geant4 based simulation will still be heavily used and is expected to consume the biggest portion of the total estimated processing time. In order to run effectively on modern architectures and profit from multi-core designs a migration of the Athena framework to a multi-threading processing model was performed. A multi-threaded simulation based on AthenaMT and Geant4MT, enables substantial decreases in the memory footprint of jobs, largely from shared geometry and cross-section tables. This approach scales better with respect to the multi-processing approach (AthenaMP) especially on the architectures that are foreseen to be used in the next LHC runs. In these proceedings we report about the status of the multi-threaded simulation in ATLAS, focusing on the different challenges of its validation process. We demonstrate the different tools and strategies that have been used for debugging multi-threaded runs versus the corresponding sequential ones, in order to have a fully reproducible and consistent simulation result.

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Gray, Heather M. "Measurement of theb-jet cross-section with associated vector boson production with the ATLAS experiment at the LHC." EPJ Web of Conferences 28 (2012): 12050. http://dx.doi.org/10.1051/epjconf/20122812050.

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LaFontaine, Caden, Bailey Tallman, Spencer Ellis, Trevor Croteau, Brandon Torres, Sabrina Hernandez, Diego Cristancho Guerrero, Jessica Jaksik, Drue Lubanski, and Roland Allen. "A Dark Matter WIMP That Can Be Detected and Definitively Identified with Currently Planned Experiments." Universe 7, no. 8 (July 27, 2021): 270. http://dx.doi.org/10.3390/universe7080270.

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A recently proposed dark matter WIMP (weakly interacting massive particle) has only second-order couplings to gauge bosons and itself. As a result, it has small annihilation, scattering, and creation cross-sections, and is consequently consistent with all current experiments and the observed abundance of dark matter. These cross-sections are, however, still sufficiently large to enable detection in experiments that are planned for the near future, and definitive identification in experiments proposed on a longer time scale. The (multi-channel) cross-section for annihilation is consistent with thermal production and freeze-out in the early universe, and with current evidence for dark matter annihilation in analyses of the observations of gamma rays by Fermi-LAT and antiprotons by AMS-02, as well as the constraints from Planck and Fermi-LAT. The cross-section for direct detection via collision with xenon nuclei is estimated to be slightly below 10−47 cm2, which should be attainable by LZ and Xenon nT and well within the reach of Darwin. The cross-section for collider detection via vector boson fusion is estimated to be ∼1 fb, and may be ultimately attainable by the high-luminosity LHC; definitive collider identification will probably require the more powerful facilities now being proposed.

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SCAPPARONE, EUGENIO. "SOFT QCD AND DIFFRACTIVE PHYSICS AT LHC." International Journal of Modern Physics A 27, no. 32 (December 30, 2012): 1230034. http://dx.doi.org/10.1142/s0217751x12300347.

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After a short introduction on the importance of the soft and of the diffractive studies in the understanding of minimum bias events, the main results obtained at LHC are discussed. This overview includes identified particle and inclusive measurements, minimum bias and underlying events, all of them shedding light on the soft process production mechanisms. The results of the inelastic cross-section measurements obtained by the LHC experiments and their compatibility are discussed together with the models used to extrapolate the data at low diffractive masses. A review of the most recent diffraction results is presented, showing the different approaches used by the LHC experiments, relying on different experimental techniques. The combination of the results obtained by ALICE, ATLAS, CMS, LHCb and TOTEM provides a wide sample of informations, covering an unprecedented pseudorapidity range. A detailed comparison between the obtained results is shown, followed by a critical discussion on the still existing discrepancies between the experimental data and the Monte Carlo used at LHC to simulate soft and diffractive physics.

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TAO, JUN-QUAN, YU-QIAO SHEN, JIA-WEI FAN, HONG XIAO, GUO-MING CHEN, HE-SHENG CHEN, JIAN-GUO BIAN, et al. "EFFECT FROM THE GLUON-FUSION SIGNAL AND BACKGROUND INTERFERENCE FOR HIGGS DECAYING TO γγ ANALYSIS AT THE LHC." Modern Physics Letters A 28, no. 18 (June 14, 2013): 1350081. http://dx.doi.org/10.1142/s0217732313500818.

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We calculate the destructive interference factors between the Higgs decay H→γγ produced in gluon-fusion and the Standard Model (SM) continuum gg→γγ process, as a function of the scattering angle in the center-of-mass frame of the final two photons. The interference factors are studied with the selections based on the acceptance criteria of the ATLAS and CMS H→γγ searches at the LHC. The result shows that the destructive interference is only at an order of 2.5% for the SM Higgs analysis at the LHC. The factors are almost the same for the same Higgs mass hypothesis but with different proton–proton collisions at [Formula: see text], 8 TeV, 13 TeV and 14 TeV. The destructive interference is far below the present uncertainty on the total cross-section prediction of Higgs, which is about 15% used at the LHC. A destructive interference factor of -2.5% is suggested to be used in the H→γγ analysis at the LHC, due to the effect from the interference for this decay channel.

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Benić, Sanjin, Kenji Fukushima, Oscar Garcia-Montero, and Raju Venugopalan. "Photons as Probes of Gluon Saturation in DiluteDense Collisions." Proceedings 10, no. 1 (April 18, 2019): 33. http://dx.doi.org/10.3390/proceedings2019010033.

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We use the Color Glass Condensate (CGC) effective field theory (EFT) to calculate inclusive photon production to leading order q g → q γ , (LO), and next-to leading order g g → q q ¯ γ (NLO) at LHC energies. These processes dominate the photon production at small-x , where x ≲ 0 . 01 in the target and projectile protons. We show that the NLO contribution dominates at values of x typical at the LHC, since its cross-section is sensitive to the gluon distributions in both protons. We perform a comparison of our results to the available inclusive photon data, from ATLAS and CMS at center-of-mass energies of 2 . 76 and 7 TeV . This data lies in the range k ⊥ > 20 GeV . We show that for this range, the k ⊥ -factorized cross-section converges to the full CGC EFT result, and can be used for the comparison. We find that it gives good agreement with experimental results. Our results are to be considered as a first step towards constraining unintegrated gluon distributions, which will be continued for larger systems, where coherent scatterings are enhanced.

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SCHILLING, FRANK-PETER. "TOP QUARK PHYSICS AT THE LHC: A REVIEW OF THE FIRST TWO YEARS." International Journal of Modern Physics A 27, no. 17 (June 26, 2012): 1230016. http://dx.doi.org/10.1142/s0217751x12300165.

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This review summarizes the highlights in the area of top quark physics obtained with the two general purpose detectors ATLAS and CMS during the first two years of operation of the Large Hadron Collider (LHC). It covers the 2010 and 2011 data taking periods, where the LHC provided pp collisions at a center-of-mass energy of [Formula: see text]. Measurements are presented of the total and differential top quark pair production cross-section in many different channels, the top quark mass and various other properties of the top quark and its interactions, for instance the charge asymmetry. Measurements of single top quark production and various searches for new physics involving top quarks are also discussed. The already very precise experimental data are in good agreement with the standard model (SM).

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Goharipour, Muhammad, and Hossein Mehraban. "Predictions for the Isolated Prompt Photon Production at the LHC ats= 13 TeV." Advances in High Energy Physics 2017 (2017): 1–10. http://dx.doi.org/10.1155/2017/3802381.

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The prompt photon production in hadronic collisions has a long history of providing information on the substructure of hadrons and testing the perturbative techniques of QCD. Some valuable information about the parton densities in the nucleon and nuclei, especially of the gluon, can also be achieved by analysing the measurements of the prompt photon production cross section whether inclusively or in association with heavy quarks or jets. In this work, we present predictions for the inclusive isolated prompt photon production in pp collisions at center-of-mass energy of 13 TeV using various modern PDF sets. The calculations are presented as a function of both photon transverse energyETγand pseudorapidityηγfor the ATLAS kinematic coverage. We also study in detail the theoretical uncertainty in the cross sections due to the variation of the renormalization, factorization, and fragmentation scales. Moreover, we introduce and calculate the ratios of photon momenta for different rapidity regions and study the impact of various input PDFs on such quantity.

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Sugano, Michinaka, Shun Enomoto, Norio Higashi, Masahisa Iida, Yukiko Ikemoto, Hiroshi Kawamata, Nobuhiro Kimura, et al. "Development of 2-m Model Magnet of the Beam Separation Dipole With New Iron Cross Section for the High-Luminosity LHC Upgrade." IEEE Transactions on Applied Superconductivity 29, no. 5 (August 2019): 1–7. http://dx.doi.org/10.1109/tasc.2019.2902710.

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Knapik, J. "Measurement of the Total Proton--Proton Cross Section at $\sqrt {s} = 7$ TeV with the ATLAS Detector at the LHC." Acta Physica Polonica B 46, no. 7 (2015): 1319. http://dx.doi.org/10.5506/aphyspolb.46.1319.

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Ding, Ran, Yizhou Fan, Li Huang, Chuang Li, Tianjun Li, Shabbar Raza, and Bin Zhu. "Systematic study of diphoton resonance at 750 GeV from sgoldstino." International Journal of Modern Physics A 31, no. 26 (September 20, 2016): 1650151. http://dx.doi.org/10.1142/s0217751x16501517.

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The ATLAS and CMS Collaborations of the Large Hadron Collider (LHC) have reported an excess of events in diphoton channel with invariant mass of about 750 GeV. With low energy supersymmetry breaking, we systematically consider the sgoldstino scalar S as the new resonance, which is a linear combination of the CP-even scalar [Formula: see text] and CP-odd pseudoscalar [Formula: see text]. Because we show that [Formula: see text] and [Formula: see text] can be degenerated or have large mass splitting, we consider two cases for all the following three scenarios: (1) Single resonance, [Formula: see text] is the 750 GeV resonance decays to a pair of 1 GeV pseudoscalar [Formula: see text] with suitable decay length, these two [Formula: see text] decay into collimated pair of photons which cannot be distinguished at the LHC and may appear as diphotons instead of four photons. (2) Twin resonances, [Formula: see text] with a mass difference of about 40 GeV and both [Formula: see text] and [Formula: see text] decay into diphoton pairs. For productions, we consider three scenarios: (I) vector-boson fusion; (II) gluon–gluon fusion; (III) [Formula: see text] pair production. In all these scenarios with two kinds of resonances, we find the parameter space that satisfies the diphoton production cross-section from 3 to 13 fb and all the other experimental constraints. And we address the decay width as well. In particular, in the third scenario, we observe that the production cross-section is small but the decay width of [Formula: see text] or [Formula: see text] can be from 40 to 60 GeV. Even if the 750 GeV diphoton excesses were not confirmed by the ATLAS and CMS experiments, we point out that our proposal can be used to explain the current and future diphoton excesses.

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Bekli, Mohamed Reda, Ilhem Chadou, and Noureddine Mebarki. "Bounds on the scale of noncommutativity from mono photon production in ATLAS Runs -1 and -2 experiments at LHC energies." International Journal of Geometric Methods in Modern Physics 18, no. 08 (May 12, 2021): 2150126. http://dx.doi.org/10.1142/s0219887821501267.

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Leading order study of direct photon production from proton–proton collisions, in the framework of Minimal (Seiberg–Witten) Non-Commutative Standard Model (NCSM), taking into account the Earth-rotation effects. We found that relative non-commutative contributions increase significantly at very high photon transverse momentum. Therefore, using Run-1 ([Formula: see text] TeV) and Run-2 ([Formula: see text] TeV) ATLAS experimental data of inclusive isolated prompt photon cross-section, TeV-Scale bounds of the non-commutativity (NC) parameter are obtained. For space-space non-commutativity, we obtain: [Formula: see text][Formula: see text]TeV, and for space-time non-commutativity, we obtain : [Formula: see text][Formula: see text]TeV.

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36

Liu, Ning, Wenyu Wang, Mengchao Zhang, and Rui Zheng. "750 GeV diphoton resonance in a vector-like extension of Hill model at a 100 TeV hadron collider." International Journal of Modern Physics A 31, no. 25 (September 8, 2016): 1650145. http://dx.doi.org/10.1142/s0217751x16501451.

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In this paper, we study the recent 750 GeV diphoton excess in the Hill model with vector-like fermions. The singlet-like Hill boson is chosen as the 750 GeV diphoton resonance. Such a scalar is mainly produced by gluon fusion via vector-like top and bottom quark loops and decays to diphoton via the vector-like quark and lepton loops. Under the current experimental and theoretical constraints, we find that the mixing angle of the singlet and doublet Higgs bosons lies within [Formula: see text] and the 750 GeV diphoton cross-section can be maximally enhanced to about 6 fb at 13 TeV LHC. Moreover, we find that the Hill boson pair production in [Formula: see text] channel can be probed at [Formula: see text] significance if [Formula: see text] and [Formula: see text] at a 100 TeV collider with 3000 fb[Formula: see text] luminosity.

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37

Nurse, Emily, and Sercan Sen. "Large Rapidity Gap Method to Select Soft Diffraction Dissociation at the LHC." Advances in High Energy Physics 2016 (2016): 1–17. http://dx.doi.org/10.1155/2016/5082847.

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In proton-proton (pp) collisions, any process involves exchanging the vacuum quantum numbers is known as diffractive process. A diffractive process with no largeQ2is called soft diffractive process. The diffractive processes are important for understanding nonperturbative QCD effects and they also constitute a significant fraction of the total pp cross section. The diffractive events are typically characterized by a region of the detector without particles, known as a rapidity gap. In order to observe diffractive events in this way, we consider the pseudorapidity acceptance in the forward region of the ATLAS and CMS detectors at the Large Hadron Collider (LHC) and discuss the methods to select soft diffractive dissociation for pp collisions ats=7 TeV. It is shown that, in the limited detector rapidity acceptance, it is possible to select diffractive dissociation events by requiring a rapidity gap in the event; however, without using forward detectors, it seems not possible to fully separate single and double diffractive dissociation events. The Zero Degree Calorimeters can be used to distinguish the type of the diffractive processes up to a certain extent.

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38

Lapertosa, A. "Measurements of the vector boson production with the ATLAS detector." EPJ Web of Conferences 172 (2018): 03001. http://dx.doi.org/10.1051/epjconf/201817203001.

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Measurements of the Drell-Yan production of W and Z bosons at the LHC provide a benchmark of our understanding of perturbative QCD and probe the proton structure in a unique way. The ATLAS collaboration has performed new high precision measurements at a center-of-mass energy of 7 TeV. The measurements are performed for W+, W- and Z bosons integrated and as a function of the boson or lepton rapidity and the Z mass. Unprecedented precision is reached and strong constraints on Parton Distribution Functions, in particular the strange density are found. Z boson cross sections are also measured at center-of-mass energies of 8 TeV and 13 TeV, and cross-section ratios to the top-quark pair production have been derived. This ratio measurement leads to a cancellation of systematic effects and allows for a high precision comparison to the theory predictions. The production of jets in association with vector bosons is a further important process to study perturbative QCD in a multi-scale environment. The ATLAS collaboration has performed new measurements of Z boson plus jets cross sections, differential in several kinematic variables, in proton-proton collision data taken at a center-of-mass energy of 13 TeV. The measurements are compared to state-of-the art theory predictions. They are sensitive to higher-order pQCD effects, probe flavour and mass schemes and can be used to constrain the proton structure. In addition, a new measurement of the splitting scales of the kt jet-clustering algorithm for final states containing a Z boson candidate at a center-of-mass energy of 8 TeV is presented.

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Civitarese, Osvaldo, Jouni Suhonen, and Kai Zuber. "Combining data from high-energy pp-reactions and neutrinoless double-beta decay: Limits on the mass of the right-handed boson." International Journal of Modern Physics E 25, no. 10 (October 2016): 1650081. http://dx.doi.org/10.1142/s0218301316500816.

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From the recently established lower-limits on the nonobservability of the neutrinoless double-beta decay of [Formula: see text]Ge (GERDA collaboration) and [Formula: see text]Xe (EXO-200 and KamLAND-Zen collaborations), combined with the ATLAS and CMS data, we extract limits for the left–right (LR) mixing angle, [Formula: see text], of the [Formula: see text] electroweak Hamiltonian. For the theoretical analysis, which is a model dependent, we have adopted a minimal extension of the Standard Model (SM) of Electroweak Interactions belonging to the [Formula: see text] representation. The nuclear-structure input of the analysis consists of a set of matrix elements and phase-space factors, and the experimental lower-limits for the half-lives. The other input are the ATLAS and CMS cross-section measurements of the [Formula: see text]-collisions into two-jets and two-leptons, performed at the large hadron collider (LHC). Our analysis yields the limit [Formula: see text] for [Formula: see text], by combining the model-dependent limits extracted from the double-beta-decay measurements and those extracted from the results of the CMS and ATLAS measurements.

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40

Kordas, Kostas. "Measurements of the Vector boson production with the ATLAS Detector." EPJ Web of Conferences 182 (2018): 02067. http://dx.doi.org/10.1051/epjconf/201818202067.

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The electroweak sector of the Standard Model can be tested by precision measurements of its fundamental parameters, such as the W boson mass or the electroweak mixing angle. In this contribution we present the first measurement of the W boson mass, based on the 7 TeV data set corresponding to an integrated luminosity of 4.6 fb-1. With this data set the detector and physics modelling have been studied in great detail, leading to an overall uncertainty of 19 MeV. The ATLAS collaboration also performed a new precise triple differential Z/γ* Drell-Yan cross-section measurement as a function of the dilepton mass, the dilepton rapidity and cos θ* defined in the Collins-Soper frame. This measurement provides sensitivity to the PDFs and the Z forward-backward asymmetry, AFB, which is derived and will be presented. The latter builds the foundation for a possible future extraction of the weak-mixing angle. The production of jets in association with vector bosons is an important process to study perturbative QCD in a multi-scale environment. The ATLAS collaboration has performed new measurements of vector boson plus jets cross sections, differential in several kinematic variables, in proton-proton collision data, taken at center-of-mass energies of 8 TeV and 13 TeV. These measurements are presented and compared to state-of-the art theory predictions. They are sensitive to higher-order pQCD effects, and can be used to constrain the proton structure. In addition, we present a new measurement of the splitting scales of the kt jet-clustering algorithm for final states containing a Z-boson candidate at a centre-of-mass energy of 8 TeV.

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41

Dado, Tomas. "Top-quark properties and mass measurements with the ATLAS detector." EPJ Web of Conferences 182 (2018): 02033. http://dx.doi.org/10.1051/epjconf/201818202033.

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The top quark is unique among the known quarks in that it decays before it has an opportunity to form hadronic bound states. This makes measurements of its properties particularly interesting as one can access directly the properties of a bare quark. The latest measurements of these properties with the ATLAS detector at the LHC [1] are presented. Measurements of top-quark spin observables in top-antitop events, each sensitive to a different coefficient of the spin density matrix, are presented and compared to the Standard Model predictions. The helicity of the W boson from the top decays and the production angles of the top quark are further discussed. Limits on the rate of flavour changing neutral currents in the production or decay of the top quark are reported. The production of top-quark pairs in association with W and Z bosons is also presented. The measurement probes the coupling between the top quark and the Z boson. The cross-section measurement of photons produced in association with top-quark pairs is also discussed. These process are all compared to the best available theoretical calculations. The latest ATLAS measurements of the top-quark mass in lepton+jets, dilepton, and all-hadronic final states are also reported. In addition, measurements aiming to measure the mass in a well-defined scheme are presented.

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Mukherjee, Swagata. "Search for R-parity violating supersymmetry and quantum blackholes in eμ final state in CMS." EPJ Web of Conferences 182 (2018): 03011. http://dx.doi.org/10.1051/epjconf/201818203011.

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A search for narrow resonances decaying to an electron and a muon is performed using an integrated luminosity of 2.7 fb-1 of 13 TeV proton-proton collision data recorded with the CMS detector at the LHC. The eμ mass spectrum is also investigated for non-resonant contributions from the production of quantum black holes (QBH). With no evidence for physics beyond the standard model in the invariant mass spectrum of selected eμ pairs, upper limits are set at 95% confidence level on the product of cross section and branching fraction for signals arising in theories with charged lepton flavour violation. In the search for narrow resonances, the resonant production of a π sneutrino in R-parity violating supersymmetry is considered. The π sneutrino is excluded for masses below 1.0 TeV for couplings λ132 = λ231 = λ'311 = 0:01 and below 3.3 TeV for λ132 = λ231 = λ'311 = 0:2. In a framework of TeV-scale quantum gravity, for models that invoke extra dimensions, the observed exclusion limits for the threshold mass of QBH production range from 2.5 TeV for one extra dimension to 4.5 TeV for six extra dimensions.

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43

Benavides, Richard H., Luis Muñoz, William A. Ponce, Oscar Rodríguez, and Eduardo Rojas. "Electroweak couplings and LHC constraints on alternative Z′ models in E6." International Journal of Modern Physics A 33, no. 35 (December 20, 2018): 1850206. http://dx.doi.org/10.1142/s0217751x18502068.

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We report the most general expression for the chiral charges of a [Formula: see text] gauge boson coming from an [Formula: see text] unification model, as a function of the electroweak parameters and the charges of the [Formula: see text] factors in the chain of subgroups. These charges are valid for an arbitrary Higgs sector and only depend on the branching rules of the [Formula: see text] fundamental representation and the corresponding rules for the fermionic representations of their subgroups. By assuming [Formula: see text] unification, the renormalization group equations (RGE) allow us to calculate the electroweak parameters at low energies for most of the chains of subgroups in [Formula: see text]. From RGE and unitary conditions, we show that at low energies there must be a mixing between the gauge boson of the standard model hypercharge and the [Formula: see text]. From this, it is possible to delimit the preferred region in the parameter space for a breaking pattern in [Formula: see text]. In general, without unification, it is not viable to determine this region; however, for some models and under certain assumptions, it is possible to limit the corresponding parameter space. By using the most recent upper limits on the cross-section of extra gauge vector bosons [Formula: see text] decaying into dileptons from the ATLAS data at 13 TeV with accumulated luminosities of 36.1 fb[Formula: see text] and 13.3 fb[Formula: see text], we report the 95% C.L. lower limits on the [Formula: see text] mass for the typical [Formula: see text] benchmark models. We also show the contours in the 95% C.L. of the [Formula: see text] mass bounds for the entire parameter space of [Formula: see text].

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44

Kumar, Satendra, Poulose Poulose, Rafiqul Rahaman, and Ritesh K. Singh. "Measuring Higgs self-couplings in the presence of V V H and V V HH at the ILC." International Journal of Modern Physics A 34, no. 18 (June 28, 2019): 1950094. http://dx.doi.org/10.1142/s0217751x19500945.

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The recent discovery of a Higgs boson at LHC, while establishing the Higgs mechanism as the way of electroweak symmetry breaking, started an era of precision measurements involving the Higgs boson. In an effective Lagrangian framework, we consider the [Formula: see text] process, at an ILC running at a center-of-mass energy of 500 GeV to investigate the effect of the [Formula: see text] and [Formula: see text] couplings on the sensitivity of [Formula: see text] coupling on this process. Our results show that the sensitivity of the trilinear Higgs self-couplings on this process has somewhat strong dependence on the Higgs-gauge boson couplings. Single- and two-parameter reaches of ILC with integrated luminosity of 1000 fb[Formula: see text] are obtained on all the effective couplings indicating how these limits are affected by the presence of anomalous [Formula: see text] and [Formula: see text] couplings. The kinematic distributions studied to understand the effect of the anomalous couplings, again, show strong influence of [Formula: see text]–[Formula: see text] couplings on the dependence of these distributions on [Formula: see text] coupling. Similar results are indicated in the case of the process, [Formula: see text], considered at a center-of-mass energy of 2 TeV, where the cross-section is large enough. The effect of [Formula: see text] and [Formula: see text] couplings on the sensitivity of [Formula: see text] coupling is clearly established through our analyses in this process.

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45

Fagundes, D. A., M. J. Menon, and P. V. R. G. Silva. "Leading components in forward elastic hadron scattering: Derivative dispersion relations and asymptotic uniqueness." International Journal of Modern Physics A 32, no. 32 (November 20, 2017): 1750184. http://dx.doi.org/10.1142/s0217751x17501846.

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Forward amplitude analyses constitute an important approach in the investigation of the energy dependence of the total hadronic cross-section [Formula: see text] and the [Formula: see text] parameter. The standard picture indicates for [Formula: see text] a leading log-squared dependence at the highest c.m. energies, in accordance with the Froissart–Lukaszuk–Martin bound and as predicted by the COMPETE Collaboration in 2002. Beyond this log-squared (L2) leading dependence, other amplitude analyses have considered a log-raised-to-gamma form [Formula: see text], with [Formula: see text] as a real free fit parameter. In this case, analytic connections with [Formula: see text] can be obtained either through dispersion relations (derivative forms), or asymptotic uniqueness (Phragmén–Lindelöff theorems). In this work, we present a detailed discussion on the similarities and mainly the differences between the Derivative Dispersion Relation (DDR) and Asymptotic Uniqueness (AU) approaches and results, with focus on the [Formula: see text] and L2 leading terms. We also develop new Regge–Gribov fits with updated dataset on [Formula: see text] and [Formula: see text] from [Formula: see text] and [Formula: see text] scattering, including all available data in the region 5 GeV–8 TeV. The recent tension between the TOTEM and ATLAS results at 7 TeV and mainly at 8 TeV is discussed and considered in the data reductions. Our main conclusions are the following: (1) all fit results present agreement with the experimental data analyzed and the goodness-of-fit is slightly better in case of the DDR approach; (2) by considering only the TOTEM data at the LHC region, the fits with L[Formula: see text] indicate [Formula: see text] (AU approach) and [Formula: see text] (DDR approach); (3) by including the ATLAS data the fits provide [Formula: see text] (AU) and [Formula: see text] (DDR); (4) in the formal and practical contexts, the DDR approach is more adequate for the energy interval investigated than the AU approach. A pedagogical and detailed review on the analytic results for [Formula: see text] and [Formula: see text] from the Regge–Gribov, DDR and AU approaches is presented. Formal and practical aspects related to forward amplitude analyses are also critically discussed.

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46

Aad, G., B. Abbott, D. C. Abbott, O. Abdinov, A. Abed Abud, K. Abeling, D. K. Abhayasinghe, et al. "Measurement of the cross-section and charge asymmetry of W bosons produced in proton–proton collisions at $$\sqrt{s}=8~\text {TeV}$$ with the ATLAS detector." European Physical Journal C 79, no. 9 (September 2019). http://dx.doi.org/10.1140/epjc/s10052-019-7199-0.

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Abstract This paper presents measurements of the $$W^+ \rightarrow \mu ^+\nu $$W+→μ+ν and $$W^- \rightarrow \mu ^-\nu $$W-→μ-ν cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton–proton collisions at a centre-of-mass energy of 8 $$\text {TeV}$$TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of $$20.2~\text{ fb }^{-1}$$20.2fb-1. The precision of the cross-section measurements varies between 0.8 and 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.

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47

Gutiérrez-Rodríguez, Alejandro, Murat Köksal, Ahmet A. Billur, and MARIA HERNANDEZ. "Prospects of measurements on the anomalous magnetic and electric dipole moments of the $\tau$-neutrino in $pp$ collisions at the LHC." SciPost Physics Proceedings, no. 1 (February 22, 2019). http://dx.doi.org/10.21468/scipostphysproc.1.044.

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In this paper the production cross-section pp\rightarrow (\gamma, Z) \to \nu_\tau \bar \nu_\tau \gamma+Xpp→(γ,Z)→ντν‾τγ+X in pppp collisions at \sqrt{s}=13, 14, 33\hspace{0.8mm}TeV is presented. Furthermore, we estimate bounds at the 95\%95% C.L. on the dipole moments of the \tauτ-neutrino using integrated luminosity of {\cal L}= 100, 500, 1000, 3000 \hspace{0.8mm}fb^{-1} collected with the ATLAS detector at the LHC and we consider systematic uncertainties of \delta_{sys} = 0\%, \, 5\%, \,10\%δsys=0%,5%,10%. We found that the current and future LHC bounds are weaker than other experiments reported in previous investigations. However, it is shown that the estimated process is a good prospect for probing the dipole moments of the \tauτ-neutrino at the LHC.

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Aad, G., B. Abbott, D. C. Abbott, A. Abed Abud, K. Abeling, D. K. Abhayasinghe, S. H. Abidi, et al. "Measurements of top-quark pair differential and double-differential cross-sections in the $$\ell $$+jets channel with pp collisions at $$\sqrt{s}=13$$ TeV using the ATLAS detector." European Physical Journal C 79, no. 12 (December 2019). http://dx.doi.org/10.1140/epjc/s10052-019-7525-6.

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AbstractSingle- and double-differential cross-section measurements are presented for the production of top-quark pairs, in the lepton + jets channel at particle and parton level. Two topologies, resolved and boosted, are considered and the results are presented as a function of several kinematic variables characterising the top and $$t\bar{t}$$ t t ¯ system and jet multiplicities. The study was performed using data from pp collisions at centre-of-mass energy of 13 TeV collected in 2015 and 2016 by the ATLAS detector at the CERN Large Hadron Collider (LHC), corresponding to an integrated luminosity of $$36~\mathrm {fb}^{-1}$$ 36 fb - 1 . Due to the large $$t\bar{t}$$ t t ¯ cross-section at the LHC, such measurements allow a detailed study of the properties of top-quark production and decay, enabling precision tests of several Monte Carlo generators and fixed-order Standard Model predictions. Overall, there is good agreement between the theoretical predictions and the data.

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Ethier, Jacob J., Raquel Gomez-Ambrosio, Giacomo Magni, and Juan Rojo. "SMEFT analysis of vector boson scattering and diboson data from the LHC Run II." European Physical Journal C 81, no. 6 (June 2021). http://dx.doi.org/10.1140/epjc/s10052-021-09347-7.

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AbstractWe present a systematic interpretation of vector boson scattering (VBS) and diboson measurements from the LHC in the framework of the dimension-six standard model effective field theory (SMEFT). We consider all available measurements of VBS fiducial cross-sections and differential distributions from ATLAS and CMS, in most cases based on the full Run II luminosity, and use them to constrain 16 independent directions in the dimension-six EFT parameter space. Compared to the diboson measurements, we find that VBS provides complementary information on several of the operators relevant for the description of the electroweak sector. We also quantify the ultimate EFT reach of VBS measurements via dedicated projections for the high luminosity LHC. Our results motivate the integration of VBS processes in future global SMEFT interpretations of particle physics data.

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Aad, G., B. Abbott, D. C. Abbott, A. Abed Abud, K. Abeling, D. K. Abhayasinghe, S. H. Abidi, et al. "Measurements of inclusive and differential cross-sections of combined $$ t\overline{t}\gamma $$ and tWγ production in the eμ channel at 13 TeV with the ATLAS detector." Journal of High Energy Physics 2020, no. 9 (September 2020). http://dx.doi.org/10.1007/jhep09(2020)049.

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Abstract Inclusive and differential cross-sections for the production of top quarks in association with a photon are measured with proton-proton collision data corresponding to an integrated luminosity of 139 fb−1. The data were collected by the ATLAS detector at the LHC during Run 2 between 2015 and 2018 at a centre-of-mass energy of 13 TeV. The measurements are performed in a fiducial volume defined at parton level. Events with exactly one photon, one electron and one muon of opposite sign, and at least two jets, of which at least one is b-tagged, are selected. The fiducial cross-section is measured to be $$ {39.6}_{-2.3}^{+2.7} $$ 39.6 − 2.3 + 2.7 fb. Differential cross-sections as functions of several observables are compared with state-of-the-art Monte Carlo simulations and next-to-leading-order theoretical calculations. These include cross-sections as functions of photon kinematic variables, angular variables related to the photon and the leptons, and angular separations between the two leptons in the event. All measurements are in agreement with the predictions from the Standard Model.

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Journal articles on the topic 'LHC ATLAS Luminosity Cross Section'

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