Bulletin of the American Physical Society
2020 Annual Meeting of the Far West Section
Volume 65, Number 17
Friday–Saturday, October 9–10, 2020; Virtual, Pacific Time
Session D03: High Energy/Accelerator PhysicsLive
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Chair: Hendrik Ohldag, Lawrence Berkeley National Laboratory |
Friday, October 9, 2020 2:00PM - 2:12PM Live |
D03.00001: Gauge Theory and 2D Physics: A Review Spencer Tamagni, Costas Efthimiou We provide a review of the interrelations between gauge theories in three and four dimensions with two-dimensional systems. In particular, we focus on Chern-Simons theory in three dimensions and theories with N=2 supersymmetry in four dimensions. Our emphasis is on how two-dimensional conformal field theory on Riemann surfaces provides a unified way of thinking about these sets of topics and elegantly encodes exact properties of the strongly coupled theories such as dualities. [Preview Abstract] |
Friday, October 9, 2020 2:12PM - 2:24PM Live |
D03.00002: Non-Abelian Firewall Douglas Singleton A simple, closed-form solution to the Yang–Mills field equations is presented which has a non-Abelian firewall — a spherical “horizon” where the energy density diverges. By the gravity/gauge duality, this non-Abelian firewall implies the existence of a gravitational firewall. Gravitational firewalls have been proposed as a way of resolving the information loss paradox, but at the cost of violating the equivalence principle. [Preview Abstract] |
Friday, October 9, 2020 2:24PM - 2:36PM Live |
D03.00003: Metrology for the ATLAS Inner Detector Pixel Upgrade Neha Singh, Kathryn Grimm ATLAS (A Toroidal LHC Apparatus) is a detector at the Large Hadron Collider (LHC) at CERN used for particle physics investigation and analysis. The inner most layer is the pixel detector that will be removed and upgraded with an all-silicon sensor called the Inner Tracker (ITk). The ITk upgrade will provide better resolution and efficiency to support a higher track density, created by the High-Luminosity-LHC (HL-LHC). Two hundred particle collisions per bunch crossing are expected (\textless $\mu $\textgreater $=$ 200), an increase from \textless $\mu $\textgreater $=$ 30 in the most recent LHC run. Additionally, existing components need to be replaced after years of heavy radiation damage. The upgraded pixel detector will consist of sensor modules glued to stave and ring components. To ensure correct construction, the components must be measured with micron-level precision using a coordinate measuring machine (CMM). This metrology is performed using the camera probe of the CMM and a part program that measures the placement of the modules onto the components. This talk will discuss the ITk upgrade and highlight the metrology procedures that will be used to qualify the detector component assembly. [Preview Abstract] |
Friday, October 9, 2020 2:36PM - 2:48PM Live |
D03.00004: Massive Photon, Magnetic Charge and the Dirac Quantization Condition Michael Dunia, Tim Evans, Douglas Singleton In this paper we correct previous work on magnetic charge plus a photon mass. We show that contrary to previous claims this system has a very simple, closed form solution which is the Dirac string potential multiplied by a exponential decaying part. Interesting features of this solution are discussed namely: (i) the Dirac string becomes a real feature of the solution; (ii) the breaking of gauge symmetry via the photon mass leads to a breaking of the rotational symmetry of the monopole's magnetic field; (iii) the Dirac quantization condition is potentially altered. [Preview Abstract] |
Friday, October 9, 2020 2:48PM - 3:00PM Live |
D03.00005: Minimum Length Scenarios via Modified Uncertainty Principles and Operators Jaeyeong Lee, Douglas Singleton, Michael Bishop, Joey Contreras The minimum length scale from theories of quantum gravity led to the modification of the Heisenberg uncertainty principle, the commutation relation, and the position operator. Previously, the generalized uncertainty principle and its modified commutation relations were the standard method to obtain a minimum length scale. However, we show that there are other modified uncertainty principle scenarios that does not necessarily require the modification of the structure of the uncertainty principle and the commutation relation. [Preview Abstract] |
Friday, October 9, 2020 3:00PM - 3:12PM Live |
D03.00006: The Cosmological Tension of Ultralight Axion Dark Matter and its Solutions Jacob Leedom, Jeff Dror A number of proposed and ongoing experiments search for axion dark matter with a mass nearing the limit set by small scale structure ($\mathcal{O}$($10^{−21}$ eV)). We consider the late universe cosmology of these models, showing that requiring the axion to have a matter-power spectrum that matches that of cold dark matter constrains the magnitude of the axion couplings to the visible sector. Comparing these limits to current and future experimental efforts, we find that many searches require axions with an abnormally large coupling to Standard Model fields, independently of how the axion was populated in the early universe. We survey mechanisms that can alleviate the bounds, namely, the introduction of large charges, various forms of kinetic mixing, a clockwork structure, and imposing a discrete symmetry. We provide an explicit model for each case and explore their phenomenology and viability to produce detectable ultralight axion dark matter. [Preview Abstract] |
Friday, October 9, 2020 3:12PM - 3:24PM Live |
D03.00007: Fake Rate Estimations in the ZH $\rightarrow$ $\gamma\gamma D$ Decay Blanca Nino Many beyond the Standard Model (SM) theories predict the existence of a dark photon which can couple to the SM Higgs. One such way to search for this signature is with the production of a Higgs boson in association to a Z boson where the Z decays to leptons and the Higgs decays to an SM photon and a dark photon. The decay of a WZ boson pair however mimics this dark photon signature. In order to take this into account, we look at the rate at which electrons are misidentified as photons, or the fake rate (FR). Here, we discuss this FR applied as a background to the ZH $\rightarrow$ $\gamma\gamma D$ decay region using data from the LHC 2015/2016 run. [Preview Abstract] |
Friday, October 9, 2020 3:24PM - 3:36PM Live |
D03.00008: Constraints on Sub-GeV Dark Matter-Electron Scattering from the DarkSide-50 Experiment David-Michael Poehlmann The DarkSide-50 experiment uses a two-phase argon time projection chamber to directly search for dark matter interactions. Light dark matter particles can scatter off of bound electrons in the detector, producing ionization signals. These S2-only events in the DarkSide-50 data set are used to place 90\% C.L.\ limits on sub-GeV dark matter-electron scattering rates. I will present these new constraints, along with expected recoil spectra for dark matter-electron scattering in argon. [Preview Abstract] |
Friday, October 9, 2020 3:36PM - 3:48PM Live |
D03.00009: Photon Dispersion in Quantum Gravity Joey Contreras, Michael Bishop, Jaeyeong Lee, Douglas Singleton Generic quantum gravity models predict minimal length scales that will lead to photon dispersion. The idea being that photons of different energies will interact with the vacuum of space and experience a shift in their velocities. When observing the arrival times of photons from gamma ray bursts however, no such dispersion is observed so it appears there is no minimal length scale. However we have a model that accounts for this lack of photon dispersion and yet still predicts the existence of a minimal length. [Preview Abstract] |
Friday, October 9, 2020 3:48PM - 4:00PM |
D03.00010: Search for Higgs boson pair production in the bb tau tau final state for the ATLAS at LHC of CERN Dan Brown Results of the optimization for vector boson fusion to maximize signal efficiency and minimize background are presented. The study surrounds the production of Higgs boson pairs (HH) where one decays to a pair of b quarks and the other to a tau lepton pair in the ATLAS detector in proton proton collisions at s $=$ 13 TeV. optimized selection cuts are needed to separate not only the background, but gluon gluon fusion as well. The mass of the 2 bjets (b quarks) and the eta separation between the bjets were a main focus, finding the optimal cuts for these variables, which was around Mjj \textgreater 900 GeV and ??jj \textgreater 4. Combining other cuts from other variables, such as the transverse momentum of the 2 bjets and 2 taus, proved to improve significance. Some cuts may have given this better significance, but ended up cutting too much of our signal. Finally a boosted decision tree (BDT) was used to optimize the separation between signal and background to achieve our optimal significance for the signal. The results of this study has been presented to the US ATLAS workshop at SLAC. [Preview Abstract] |
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