Bulletin of the American Physical Society
APS April Meeting 2013
Volume 58, Number 4
Saturday–Tuesday, April 13–16, 2013; Denver, Colorado
Session G12: Searches I |
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Sponsoring Units: DPF Chair: Bob Bernstein, Fermi National Accelerator Laboratory Room: Plaza Court 1 |
Sunday, April 14, 2013 8:30AM - 8:42AM |
G12.00001: Dark photon search and the Higgs-strahlung channel Igal Jaegle Many extensions of the Standard Model introduce an additional U(1) interaction, which is mediated by a U(1) boson, often by a Higgs mechanism adding a dark Higgs (or dark Higgses) to the models. This gauge boson, also known as the ``Dark Photon,'' typically has very weak coupling to Standard Model particles. Experimental results from direct Dark Matter searches, (e.g. DAMA/LIBRA) and other experimental anomalies (e.g. g-2), can be explained by such an additional interaction. Dark gauge bosons are typically of low mass; of order MeV to GeV. The ideal tools to discover such particles are therefore not high-energy collider experiments, but lower-energy high-luminosity collider experiments like Belle and BaBar, or dedicated fixed target experiments, several of which are planned or already under construction at JLAB (Newport News, USA) or at MAMI (Mainz, Germany), for example. In Belle, the search of the dark photon focuses on the so-called Higgs-strahlung channel, where a dark photon and a dark Higgs are produced. Preliminary results will be presented and discussed. [Preview Abstract] |
Sunday, April 14, 2013 8:42AM - 8:54AM |
G12.00002: Photon-Axion Mixing Effects and Mirror Cavity Experiments Carol Scarlett, Mikhail Khankhasayev It is well known that the existence of a light pseudoscalar particle called the axion can solve fundamental physical problems (e.g. the strong CP problem). We discuss the possibility of detection axions via their mixing with photons in a mirror cavity. The mixing of photons with axions in an inhomogeneous magnetic field creates a vacuum polarization that splits a light beam. In a mirror cavity, this splitting results in a bifurcation effect. Here we present the formalism to provide an effective model to study bifurcation and to account for nonzero axion masses. Both of these represent new and significant developments to furthering the current body of knowledge on the subject. [Preview Abstract] |
Sunday, April 14, 2013 8:54AM - 9:06AM |
G12.00003: ABSTRACT WITHDRAWN |
Sunday, April 14, 2013 9:06AM - 9:18AM |
G12.00004: A search for baryon-number-violating decays of the $\Lambda$ using CLAS at JLab Michael McCracken, Matt Bellis We present the status of a search for baryon-number-violating decays of the $\Lambda$ baryon using data from the CLAS detector for photoproducton off of the proton in liquid hydrogen. The dataset contains roughly $3.0\times10^6$ $\Lambda$ production events that are reconstructable from three charged final-state tracks (recoil $K^+$ and decay products). We investigate nine potential decay modes in which the $\Lambda$ decays to a meson-lepton pair. We perform a blind analysis during the optimization of data selection criteria. We estimate that the analysis will be sensitive to branching fractions on the order of $\Gamma_{\textrm{BNV}}/\Gamma_{\textrm{tot}} \approx 6\times 10^{-5}$, roughly an order of magnitude smaller than those of the currently known rare $\Lambda$ decays. [Preview Abstract] |
Sunday, April 14, 2013 9:18AM - 9:30AM |
G12.00005: Search for stopped particles produced in pp collisions at CMS Marissa Rodenburg Many extensions to the Standard Model predict heavy quasi-stable particles which would decay out-of-time with the collisions that produced them. We present the results of a search for such long-lived particles which have stopped in the Compact Muon Solenoid (CMS) detector after being produced in ?s = 8 pp collisions from CERN's Large Hadron Collider (LHC). We looked for the subsequent decay of these particles during time intervals where there were no pp collisions in the CMS experiment. In particular, we searched for decays during gaps between crossings in the LHC beam structure. We recorded such decays with a dedicated calorimeter trigger yielding a dataset that is sensitive to an integrated luminosity of up to 19.0 fb$^{-1}$, depending on the gluino lifetime. [Preview Abstract] |
Sunday, April 14, 2013 9:30AM - 9:42AM |
G12.00006: The Heavy Photon Search Experiment at Jefferson Laboratory Sho Uemura The Heavy Photon Search (HPS) is a new experiment at Jefferson Lab that will search for massive U(1) vector bosons (also known as heavy photons, dark photons, or $A'$) of mass 20--1000 MeV that couple to electric charge with relative coupling $\alpha'/\alpha$ of $10^{-5}$--$10^{-10}$. The HPS experiment is designed to produce heavy photons by electron scattering off a fixed target, and detect them using two decay channels ($e^+e^-$ or $\mu^+\mu^-$ pairs) and two signatures (invariant mass resonance and displaced decay vertex). The detector is a compact, large-acceptance forward spectrometer comprising a silicon microstrip tracker for momentum measurement and vertexing, an electromagnetic calorimeter for triggering on $e^+e^-$, and a muon detector for triggering on $\mu^+\mu^-$. This talk will cover the motivations for heavy photons and give an overview of the HPS experiment. [Preview Abstract] |
Sunday, April 14, 2013 9:42AM - 9:54AM |
G12.00007: Identifying Displaced Decays of Long-lived Hidden Sector Particles Heather Russell We present a study of employing jet substructure techniques to identify decays of long-lived neutral particles to heavy quark pairs when these decays occur in the ATLAS Inner Detector. As a baseline model for these studies, we use the hidden valley scenario proposed by Strassler and Zurek (arXiv:hep-ph/0605193), where a Higgs boson decays to a pair of long-lived neutral pseudo scalars ($\pi_ v$'s), which proceed to decay to heavy quark pairs. Jets from these decays have transverse energy in the range of $60-70$ GeV and consequently deposit most of their energy in the ATLAS electromagnetic calorimeter, allowing for jet reconstruction with relatively high spatial accuracy. [Preview Abstract] |
Sunday, April 14, 2013 9:54AM - 10:06AM |
G12.00008: Search for Lightly Ionizing Particles (LIPs) using CDMS-II detectors Kunj Prasad The Cryogenic Dark Matter Search (CDMS) collaboration employs germanium crystals instrumented with both ionization and athermal phonon sensors to perform direct searches for Dark Matter. Alternately, the low energy threshold allows search for fractional electromagnetic-charged particles, or Lightly Ionizing Particles (LIPs), moving at relativistic speed. The tower-like stacking of detectors allows background rejection by requiring the energy depositions to have sizes and locations consistent with coming from a straight fractionally charged track. We will present the results of the world's first search for LIPs with fractional charges between e/6 and e/200, and describe the improved sensitivity to LIPs-search achievable in the next phase of our program, SuperCDMS SNOLAB. [Preview Abstract] |
Sunday, April 14, 2013 10:06AM - 10:18AM |
G12.00009: APEX: The A Prime EXperiment at Jefferson Lab James Beacham APEX is a fixed target experiment at Thomas Jefferson National Accelerator Facility (JLab) in Virginia, USA, that searches for a new gauge boson ($A'$) with sub-GeV mass and coupling to ordinary matter of $g' \sim (10^{-2} - 10^{-6}) e$. Electrons impinge upon a fixed target of high-Z material to produce an $A'$ via a process analogous to photon bremsstrahlung, which then decays to an $e^{+}e^{-}$ pair that is detected by the JLab Hall A High Resolution Spectrometers. A test run was held in July of 2010, covering an $A'$ mass range from 175 to 250 MeV and couplings $g'/e > 10^{-3}$ . A full run is approved and will cover $m_{A'} \sim$ 65 to 525 MeV and $g'/e > 2.3 \times 10^{-4}$ . I will present the results of the test run and report on the current status of preparations for the full run. [Preview Abstract] |
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