Bulletin of the American Physical Society
APS April Meeting 2021
Volume 66, Number 5
Saturday–Tuesday, April 17–20, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session B19: Dark Matter with Particle Accelerators and BeyondLive
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Sponsoring Units: DPF Chair: Matteo Cremonesi, Fermilab |
Saturday, April 17, 2021 10:45AM - 10:57AM Live |
B19.00001: Search for monotop in the leptonic channel in proton-proton collisions at √s = 13 Tev in the CMS detector Rishabh Uniyal Dark Matter consists of around 27% of the total mass energy of the universe (or 5 times the mass of ordinary matter) and it does not interact directly with light so we haven’t observed it directly. Astrophysical observations like Gravitational Lensing (bending of light coming from distant galaxies by other galaxies clusters) and motion of galaxies at speeds so high for ordinary matter to sustain, have provided evidence for the presence of Dark Matter. In this talk we will look at the current status of the search for Dark Matter in events with large missing transverse energy and a leptonically decaying, boosted top quark (t -> b l v_{l}) using LHC Run II data collected by the CMS detector. A neutral bosonic state V is produced in association with the top quark decaying into two Dark Matter Candidates χ. The analysis is based on a flavor changing neutral interaction which is not possible at tree level in the SM. [Preview Abstract] |
Saturday, April 17, 2021 10:57AM - 11:09AM Live |
B19.00002: Search for Dark Matter produced in association with top quarks Victor Shang A search for Dark Matter produced in association with top quarks is presented. The search is performed using 137 fb-1 of pp collisions recorded at a center of mass energy of 13 TeV with the CMS detector at the LHC. The signature investigated include those yielding top quark pairs or a single top quark plus missing transverse energy, including both semileptonic and hadronic final states. This work focuses in particular on Dark Matter production through scalar and pseudoscalar interactions, which enhance the discovery potential of the LHC under this assumption. [Preview Abstract] |
Saturday, April 17, 2021 11:09AM - 11:21AM Live |
B19.00003: Probing Axion-like particles (ALPs) with $\gamma \gamma$ final states from Vector Boson Fusion Processes at the LHC Elijah Sheridan, Andres Flórez, Alfredo Gurrola, Will Johns, Paul Sheldon, Kuver Sinha, Brandon Soubasis Axion-like particles (ALPs) are pseudo-Nambu-Goldstone bosons of spontaneously broken global symmetries in theories attempting to address the incompleteness of the Standard Model (SM). In particular, ALPs arise in theoretical resolutions to the strong CP problem, offer explanations for the dark matter (DM) relic abundance, and are ubiquitous in string theory. The ALP mass $m_a$ can range from eV to TeV scale, and thus the ALPs parameter space includes regions relevant to a variety of astronomical, high-precision low-energy, and high-energy collider experiments. The focus of this talk is a feasibility study searching for ALPs using vector boson fusion (VBF) processes at the Large Hadron Collider (LHC). We consider the $a \to \gamma\gamma$ decay mode to show that the requirement of an energetic diphoton pair combined with two forward jets with large dijet mass and pseudorapidity separation can significantly reduce the SM backgrounds, leading to a $5\sigma$ discovery region spanning $m_a$ values from MeV scale to TeV scale and revealing LHC sensitivity to previously unstudied regions of the ALP parameter space. [Preview Abstract] |
Saturday, April 17, 2021 11:21AM - 11:33AM Live |
B19.00004: Search for dark photons in the $\text{VBF} + E_\text{T}^\text{miss} + \gamma$ final state with ATLAS at $\sqrt{s} =$ 13 TeV Lacey Rainbolt, Young-Kee Kim The ATLAS Collaboration has performed a search for a Higgs boson ($H$) that is produced via vector boson fusion (VBF) and decays to a photon and a dark photon, using $pp$ collision data collected at $\sqrt{s} =$ 13 TeV and corresponding to an integrated luminosity of 139 fb$^{-1}$. Events are required to be consistent with the VBF topology, characterized by a pair of forward jets, and must also contain a final-state photon and large missing transverse momentum representing the dark photon. No significant excess of events above the expectation from the standard model background is found. Assuming a Higgs boson mass of 125 GeV, upper limits on the $H \to \gamma \gamma_d$ branching fraction are set by fitting the distribution of the transverse mass of the photon and the missing transverse momentum. Additionally, upper limits on the product of the cross section and the $\gamma \gamma_d$ branching fraction are set for Higgs-like mediators of various masses in the narrow width approximation. [Preview Abstract] |
Saturday, April 17, 2021 11:33AM - 11:45AM Live |
B19.00005: Cosmological abundances of electroweak Dark Matter models for future high-energy colliders Marco Costa, Salvatore Bottaro, Ludovico Vittorio, Dario Buttazzo, Roberto Franceschini, Paolo Panci, Diego Redigolo The simplest extension to the Standard Model (SM) which can accommodate a Dark Matter (DM) candidate consists of a single additional $SU(2)_L$ $n-$plet with 0 or milli-hypercharge. We require odd $n$ in order to evade direct detection constraints and $n\leq 7$ to avoid electroweak Landau poles too close to the DM mass. In view of a possible future high-energy lepton collider, it is of prominent importance to precisely determine the DM mass required to reproduce the observed cosmological abundance. Such a computation relies on the precise determination of the DM annihilation cross-section, which includes non-perturbative effects like the Sommerfeld enhancement and especially the bound states formation. Up-to-date, a precise prediction of the DM mass is available only for the triplets and the Majorana 5-plet (A. Mitridate et al., JCAP, 05 (2017)). We refine and extend these computations in order to encompass all the $n-$plets up to $n=7$. For such large electroweak charges the non-perturbative effects are enhanced, and push the predicted DM mass to tens of TeV. In particular, we find a thermal mass of 36 TeV and 44 TeV for Complex Scalar and Majorana 7-plets, respectively. These could both be probed at a multi-TeV muon collider. [Preview Abstract] |
Saturday, April 17, 2021 11:45AM - 11:57AM Live |
B19.00006: Study of Higgs and Vector Portals to Dark Matter Tamer Elkafrawy, Mehdi Rahmani, Marcus Hohlmann A study of long-lived dark matter particles is performed for a dark Z boson that either couples directly to quarks and leptons or mixes kinetically with the standard model Z boson. Production via a vector portal and the Higgs portal are considered. The impact of additionally mixing the standard model Higgs with a dark Higgs boson on the production and decays of the dark Z is evaluated. Specifically, decays with a final state of displaced dimuons are considered where the dark Z and the dark Higgs decay directly to a dimuon or indirectly via dark scalars or fermions to an even number of dimuons. These can give rise to final states with large muon multiplicities. The production and total cross sections of the processes of interest as well as decay widths and decay lengths are calculated using analytical methods and Monte Carlo simulation. The sensitivity for such searches in Runs 2 and 3 of the Large Hadron Collider is discussed. Kinematics of the displaced dimuons is also investigated. [Preview Abstract] |
Saturday, April 17, 2021 11:57AM - 12:09PM Live |
B19.00007: Collider and Direct Detection Limits on Effective WIMP Dark Matter Jeffrey Hutchinson, Kara Farnsworth We analyze the limits from the 36 fb$^{\mathrm{-1}}$ ATLAS jets and missing transverse momentum search, direct detection limits from XENON1T, and projected detect detection limits from XENON, LZ, and DARWIN on Effective WIMP dark matter, a minimal extension to the standard model with thermal relic dark matter. This dark matter is a gauge singlet which couples to the standard model through a renormalizable coupling to quarks and a new quark partner particle. Within this framework, we consider six models where dark matter is either a real scalar boson, complex scalar boson, Majorana fermion, Dirac fermion, real vector boson, or complex vector boson. The observed dark matter abundance is used as a constraint on the model to reduce the parameter space down to the dark matter and partner masses. Direct detection searches rule out complex scalar and Dirac dark matter where the coupling is perturbatively small. Collider limits are the primary constraint on the other models, ruling out dark matter masses under roughly 1-2 TeV and partner masses under roughly 2-5 TeV with a loss of sensitivity near the degeneracy of the masses and additional sensitivity for light dark matter. [Preview Abstract] |
Saturday, April 17, 2021 12:09PM - 12:21PM Live |
B19.00008: Searching for Sterile Neutrinos and AcceleratorProduced Dark Matter with the CoherentCAPTAIN-Mills (CCM) Detector at the LosAlamos Neutron Science Center T.J. Schaub The MiniBooNE and LSND experiments have shown compelling evidence for sterile neutrinos in short baseline neutrino oscillation experiments. In these experiments, an excess of electron neutrino appearance was observed from a pure muon neutrino beam, and if these data are interpreted as sterile neutrino oscillations, the mass scale is \textasciitilde 1 eV$^2$. Coherent CAPTAIN-Mills (CCM) is a new experiment to search for muon neutrino disappearance at the LSND energy scale. CCM will use a 10-ton liquid argon scintillation detector to leverage the enhanced cross section from coherent elastic neutrino-nucleus scattering. CCM will operate at the Lujan Center at LANSCE which is a 100-kW stopped pion source that delivers an 800-MeV proton beam onto a tungsten target at 20 Hz with a pulse width of 275 ns. This fast pulsing is crucial for isolating the monoenergetic muon neutrino in time and reducing neutron backgrounds. Furthermore, new vector portal dark sector models predict beam dump experiments like CCM are sensitive to sub-GeV dark matter. In this talk, I will describe sterile neutrino and dark matter production and detection as well as the CCM detector and sensitivities. [Preview Abstract] |
Saturday, April 17, 2021 12:21PM - 12:33PM Live |
B19.00009: Search for dark matter in association with a hardronic top quark and a bottom quark Tielige Mengke A search for dark matter using events containing a hadronically decaying top quark, one b jet arising from initial-state gluon-splitting, no leptons, and a large imbalance in transverse momentum is presented. The data being used were collected from proton-proton collisions at $\sqrt{s}$ = 13 TeV with CMS detector at the LHC and corresponding to an integrated luminosity of 137 $fb^{-1}$. The results are interpreted based on a simplified dark matter model that provides explanation for observed proximity of the dark matter and baryon abundances. [Preview Abstract] |
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