Bulletin of the American Physical Society
Fall 2012 Meeting of the APS Ohio-Region Section
Volume 57, Number 6
Friday–Saturday, October 5–6, 2012; Detroit, Michigan
Session EA: High Energy and Nuclear Physics |
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Chair: Gil Paz, Wayne State University Room: McGregor Conference Center BC |
Saturday, October 6, 2012 8:00AM - 8:12AM |
EA.00001: Resonance Width Distribution for Open Chaotic Quantum Systems Gavriil Shchedrin Recent measurements of resonance widths, $\Gamma$, for low-energy neutron scattering off heavy nuclei claim significant deviations from the standard chi-square $\chi^{2}_{1}(\Gamma)$, or the Porter-Thomas, distribution. The unstable nucleus is an open quantum system, where the intrinsic dynamics has to be supplemented by the coupling of chaotic internal states through the continuum. We propose a new resonance width distribution based on the random matrix theory for an open quantum system. For a single open channel, the new distribution is $P(\Gamma)=C\chi^{2}_{1}(\Gamma)\sqrt{\sinh{\kappa}/{\kappa}}$ where $\kappa={\pi\Gamma}/{2D}$ and $D$ is the mean energy level spacing. This result naturally recovers the Porter-Thomas distribution for small $\kappa$ and can be directly applied to a whole range of mesoscopic systems, and is invariant under $\Gamma\rightarrow{\eta-\Gamma}$, where$\eta$ is the total width. The realistic situation in nuclei is not that of a single neutron channel. Many photon channels are always opened which modifies the width distribution into $P(\Gamma,\gamma)=C\chi^{2}_{1}(\Gamma-\gamma)\sqrt{\sinh{\kappa_{\gamma}}/{\kappa_{\gamma}}}$ with $\kappa_{\gamma}={\pi(\Gamma-\gamma)}/{2D}$, and the whole distribution is shifted by $\gamma$, an average radiation width. [Preview Abstract] |
Saturday, October 6, 2012 8:12AM - 8:24AM |
EA.00002: Soft Photons and Leptonic B Decays Kristopher Healey, Aditya Yechan Gunja, Alexey Petrov The leptonic decay of the neutral B meson $B^0_s$ into a di-muon pair is an example of a flavor-changing neutral current (FCNC) process. Studies of such decay processes not only play an important role in probing the standard model (SM) of particle physics but also provide sensitive indirect searches for new physics (NP) which predict substantial increases over the suppressed SM branching ratio. We look at the possible contributions to the standard model prediction stemming from decays with an additional outgoing photon, thus lifting a suppression that is existent in the predominant decay. While technically a different process, these additional contributions may be included in experimental measurements thus inflating the reported branching ratio. [Preview Abstract] |
Saturday, October 6, 2012 8:24AM - 8:36AM |
EA.00003: Observation of $D^0 \to \eta \omega$ Mackenzie Smith, David Cinabro Numerous singly-Cabibbo-suppressed charm meson decays are as yet unobserved. Here we report the updated observation of $D^0 \to \eta \omega$ in the CLEO data set. Besides the value of branching fraction of this decays in helping to measure $\eta-\eta^\prime$ mixing, it is an important background in $D^0$ Dalitz decays, such as $D^0 \to K^0_s \pi^0 \eta$ which is where we first noticed it. [Preview Abstract] |
Saturday, October 6, 2012 8:36AM - 8:48AM |
EA.00004: Searching for super-WIMPs in leptonic heavy meson decays Aditya Yechan Gunja, Kristopher Healey, Alexey Petrov We study constraints on the models of bosonic super-weakly interacting particle (super-WIMP) dark matter (DM) with DM masses $m_X \sim \mathcal{O}$(1 - 100) keV from leptonic decays $M\rightarrow \ell \bar{\nu}_\ell + X$, where $M=B^\pm, D^\pm, D_s^\pm$ is a heavy meson state. We focus on two cases where $X$ denotes either a light pseudoscalar (axion-like), or a light vector state that couples to the standard model (SM) through kinetic mixing. We note that for a small DM mass these decays are separately sensitive to DM couplings to quarks, but not its mass. [Preview Abstract] |
Saturday, October 6, 2012 8:48AM - 9:00AM |
EA.00005: LUX Cryogenics and Circulation Adam Bradley LUX is a new dark matter direct detection experiment being carried out at the Sanford Underground Research Facility, at the renewed Homestake mine in Lead, SD. The detector's large size supports effective internal shielding from natural radioactivity of the surrounding materials and environment. The LUX detector consists of a cylindrical vessel containing 350 kg of liquid xenon (LXe) cooled down and maintained at 175-K operating temperature using a novel cryogenic system. We report the efficiency of our thermosyphon-based cooling system, as well as the efficiency of a unique internal heat exchanger with standard gas phase purification using a heated getter, which allows for very high flow purification without requiring large cooling power. Such systems are required for multi-ton scale up. [Preview Abstract] |
Saturday, October 6, 2012 9:00AM - 9:12AM |
EA.00006: Scalar Dark Matter \& Vacuum Stability Matthew Gonderinger The Standard Model of particle physics is a highly successful theory of fundamental particle interactions, especially in light of the recent discovery of a Higgs-like boson at the LHC. Nonetheless, the SM is known to be incomplete because it does not contain a suitable dark matter candidate. Scalar extensions of the SM are simple but nonetheless interesting and well-motivated models that provide a dark matter candidate particle. I present a vacuum stability analysis - which ensures the ground state of the theory has the correct properties - of two of these models. The analysis reveals that light dark matter (10 GeV) requires a moderate self-interaction strength and new physics at or below the 10$^9$ GeV scale in the first model, and a light (order 10 to 100 GeV) Higgs-like particle with reduced couplings and additional new physics below 1000 TeV in the second model. Experimental limits from dark matter direct detection are also included. [Preview Abstract] |
Saturday, October 6, 2012 9:12AM - 9:24AM |
EA.00007: Search for Exclusive $W$ Boson Decays Christopher Clarke The $W$ boson is an important part of the standard model for its role as a mediator of the weak force, and as such has been studied extensively. It's mass has been measured by LEP and Tevatron experiments. Since the first $W$'s were produced at the $Sp\bar{p}S$ in the 1980's the properties of the $W$ boson have been studied at the Tevatron, LEP, and the LHC. None of these studies have reconstructed an exclusive $W$ boson decay. We propose to search for the exclusive decay $W^\pm \to J/\psi D_s^\pm$ and related low-multiplicity, partially reconstructed decays. The chosen mode yields an all charged track final state where $J/\psi \to \mu^+\mu^-$ and $D_s^\pm \to K^+K^-\pi^\pm$. This final state has a good trigger signature, the $J/\psi \to \mu^+\mu^-$ decay, and a number of constraints to suppress background. We discuss the possible yields in data from the CDF and CMS experiments. [Preview Abstract] |
Saturday, October 6, 2012 9:24AM - 9:36AM |
EA.00008: FFLO States in Holographic Superconductors James Alsup, Eleftherios Papantonopoulos, George Siopsis We discuss the gravity dual of FFLO states in strongly coupled superconductors. The gravitational theory utilizes two $U(1)$ gauge fields and a scalar field coupled to a charged AdS black hole. The first gauge field couples with the scalar sourcing a charge condensate below a critical temperature, and the second gauge field incorporates a magnetic field that couples to spin in the boundary theory. The scalar is neutral under the second gauge field. By turning on a magnetic interaction between the second $U(1)$ field and the scalar, it is shown that, in the high-field limit, an inhomogeneous solution possesses a higher critical temperature than the homogeneous case, giving rise to FFLO states close to zero temperature. [Preview Abstract] |
Saturday, October 6, 2012 9:36AM - 9:48AM |
EA.00009: Measurement of Anomalous Trilinear Couplings of Electroweak Gauge Bosons Kevin Siehl The standard model of particle physics predicts specific couplings between the electroweak gauge bosons with each other. Any deviation of these couplings from the standard model predictions is a sign of new physics. We use MCFM to simulate the production of WW and WZ boson pairs for a range of coupling values around standard model values. Comparing cross sections in the simulations to data allows us to measure anomalous trilinear gauge couplings, or place limits on them. [Preview Abstract] |
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