Bulletin of the American Physical Society
APS April Meeting 2023
Volume 68, Number 6
Minneapolis, Minnesota (Apr 15-18)
Virtual (Apr 24-26); Time Zone: Central Time
Session C11: QCD, Weak Decays of Heavy Quarks |
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Sponsoring Units: DPF Chair: Christopher Hilgenberg, University of Minnesota Room: Marquette II - 2nd Floor |
Saturday, April 15, 2023 1:30PM - 1:42PM |
C11.00001: Measurement of the top quark-antiquark pair charge asymmetry in events with highly boosted top quarks in proton-proton collisions at 13 TeV with the CMS detector. Beren Ozek The top quark is the heaviest elementary particle, making it a unique tool to search for new physics. In this talk, I will present a new measurement of the top quark pair charge asymmetry for highly boosted top quarks decaying to a single lepton, missing transverse momentum and jets. The analysis is performed on 13TeV proton-proton collision data recorded by the CMS experiment during Run 2. We have defined a dedicated phase space that selects top quark antiquark pairs with invariant mass greater than 750GeV in a semileptonic final state where the lepton is not necessarily isolated. This highly boosted sample is enhanced in valence quark production and thus expected to be more sensitive to deviations in the charge asymmetry caused by BSM processes. Dedicated tagging techniques are used to identify the decay products of hadronic top quarks and W bosons. An unfolding procedure is used to correct for detector resolution and acceptance, and inefficiencies in the event reconstruction. The result is presented in the full phase space at parton level and can be used as input to global EFT interpretations. |
Saturday, April 15, 2023 1:42PM - 1:54PM |
C11.00002: Entanglement Entropy in ttbar Transverse Momentum Differential Cross Section Distributions Oliver K Baker, Mira Varma We explore a novel method for studying proton-proton collisions, using both ATLAS and CMS results. Since both protons are initially in a pure state, we note that after the protons collide, their overlap region (collision region) is entangled with the non-overlap region (spectator region). The degree of entanglement between these two regions is given by the entanglement entropy. This idea is supported by showing that the ttbar differential cross section results at various transverse momenta can be described by a fit with a thermal component and a hard scattering component. When the collision and spectator regions are entangled, there is both a thermal and a hard scattering component. Consequently, when there is no entanglement present, only the hard scattering component survives. |
Saturday, April 15, 2023 1:54PM - 2:06PM |
C11.00003: Analysis of the Hadronic Resonance Structures in the J/psi J/psi Invariant Mass Spectrum Mohit V Srivastav A search is reported for low-mass hadronic structures in the J/psi J/psi mass spectrum produced by proton-proton collisions at the LHC and analyzed within the CMS experiment. The properties of the resonance structures are reported, and tools for such analyses are discussed. |
Saturday, April 15, 2023 2:06PM - 2:18PM |
C11.00004: Comment on the subtlety of defining real-time path integral in lattice gauge theories Nobuyuki Matsumoto Recently, Hoshina, Fujii, and Kikukawa in PoS LATTICE2019, 190 (2020) pointed out that the naive lattice gauge theory action in Minkowski signature does not result in a unitary theory in the continuum limit, and Kanwar and Wagman in PRD 104, no.1, 014513 (2021) proposed alternative lattice actions to the Wilson action without divergences. We here show that the subtlety can be understood from the asymptotic expansion of the modified Bessel function, which has been discussed for path integral of compact variables in nonrelativistic quantum mechanics by W. Langguth and A. Inomata [J. Math. Phys. 20, 499-504 (1979)]. The essential ingredient for defining the appropriate continuum theory is the iε prescription, which we show is applicable also for the Wilson action. It is here important that the iε should be implemented for both timelike and spacelike plaquettes. We then argue that such iε can be given a physical meaning that they remove singular paths having nontrivial winding for an infinitesimal time evolution that do not have corresponding paths in the continuum. Such point of view is only apparent in systems with compact variables as lattice gauge theories. |
Saturday, April 15, 2023 2:18PM - 2:30PM |
C11.00005: Template Fit Studies for tt¯+ c cross section measurement analysis using the ATLAS Detector Calvin Ainsworth A strategy of the tt¯ production with additional c-quark jets in the dilepton channel is presented using the LHC proton-proton collision data at the center-of-mass energy √ s = 13 T eV collected with the ATLAS detector at the LHC. The dataset corresponds with an integrated luminosity of 139 fb-1 . Events with exactly one electron, exactly one muon, at least three jets in the final state and with at least two jets containing b-hadrons, are used to determine the tt¯+ c production cross section through a template fit. In this presentation, the performance of the method using template fits is discussed. |
Saturday, April 15, 2023 2:30PM - 2:42PM |
C11.00006: Response of a Holographic Confining Theory to External Electromagnetic Fields Davoud Masoumi, Leila Shahkarami, Farid Charmchi Indirect approaches can sometimes lead to solutions to problems that are difficult or impossible to solve by direct methods. Notions of duality, in which a mapping is identified between two seemingly different theories, are especially fruitful sources of indirect methods. In particular, gauge/gravity duality, in which quantum field theories are seen as equivalent to theories of gravity in one higher dimension, has led to solutions to previously intractable problems. We utilize a form of gauge/gravity duality (the so-called "AdS/QCD correspondence") to investigate the response of a QCD-like gauge theory —i.e., holographically dual to the Andreev-Zakharov model (a deformed AdS5 model)— to constant electromagnetic fields. This approach enables us to discuss the Schwinger effect for quark-antiquark pairs. We study the Schwinger effect for three cases: a quadratic correction, a logarithmic correction, and both quadratic and logarithmic corrections. For each case, we set values of parameters such that the quark-antiquark potential in the holographic QCD model matches experimental data and lattice results. We show that an external magnetic field perpendicular to the electric field decreases the quark-antiquark pair production rate. On the contrary, a pure parallel magnetic field increases the pair production rate if a perpendicular magnetic field is also present. |
Saturday, April 15, 2023 2:42PM - 2:54PM |
C11.00007: Fully-resolved measurement of energy-energy correlators in 13 TeV pp collisions with the CMS experiment Simon Rothman Measurement of jet substructure plays a vital role in our understanding of high-energy QCD dynamics. This has traditionally been measured with various global observables such as N-subjettiness which seek to summarize the distribution of particle momenta into a single number per jet. However, there has recently been great interest in the theory community in reformulating the study of jet substructure in terms of correlators of energy flow operators. These new observables describe each jet as a distribution of energy flows and allow direct access to QCD effects such as asymptotic freedom, the confinement transition, and the dead cone effect. In this work we will discuss the challenges in measuring and unfolding these energy flow correlators and present a fully pT- and flavor-resolved measurement in 13 TeV proton-proton collisions. |
Saturday, April 15, 2023 2:54PM - 3:06PM |
C11.00008: Measurement of the cross-section ratio of four-jet production over three-jet production in the ATLAS experiment Zahra Farazpay Measurements of multi-jet cross-section ratios are presented. The data were collected with the ATLAS detector in proton-proton collisions at a center of mass energy of 13.6 TeV during 2015-2018 (Run 2) at the Large Hadron Collider. The measured quantities are the ratio of the four-jet and three-jet cross-sections and the ratio of the four-jet and two-jet cross-sections. The results are presented as a function of the jet transverse momentum. Predictions from different Monte Carlo event generators are compared to the data. The values of the strong coupling constant are extracted from the jets cross-sections ratios. |
Saturday, April 15, 2023 3:06PM - 3:18PM |
C11.00009: Quark gluon coupling and entanglement in confinement suresh AHUJA Weakly-interacting massive particles (WIMPs) with masses around the electroweak scale |
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