Bulletin of the American Physical Society
2013 Annual Fall Meeting of the APS Prairie Section
Volume 58, Number 15
Thursday–Saturday, November 7–9, 2013; Columbia, Missouri
Session C1: Particle Physics II |
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Chair: Mark Neubauer, University of Illinois Room: Memorial Union Benton Bingham |
Friday, November 8, 2013 10:30AM - 10:42AM |
C1.00001: Studies of the CMS HF ``aging'' effect at the High-luminosity LHC Kamuran Dilsiz The Hadronic Forward Calorimeters (HF) at the CMS are instrumented to have a pseudorapidity coverage from 3.0 to 5.0 in the CMS laboratory frame. It plays a key role in identifying forward jets to study the Higgs boson produced in vector boson fusion (VBF) processes. After the proposed high-luminosity LHC upgrade, during the course of running the quartz fibres used in the HF readout are expected to receive significant radiation dose and the performance of the forward jet reconstruction could be degraded, an ``aging'' effect. This could degrade the performance of the Higgs studies in VBF channels. In this talk, we present a study of this ``aging'' effect using CMS fast Monte-Carlo simulations in the context of VBF Higgs decaying into taus. Preliminary results show that the VBF signal is not significantly diminished by the ``aging'' effect in the HF. [Preview Abstract] |
Friday, November 8, 2013 10:42AM - 10:54AM |
C1.00002: J/$\psi $ photo-production at the Relativistic Heavy Ion Collider with STAR. L. Chanaka De Silva Ultra-peripheral collision events are effectively photo-production on nuclear targets. Relativistic heavy ions carry strong transverse electromagnetic fields that can be treated as sources of quasi-real virtual photons. The ions interact through photon-pomeron and photon-photon collisions at impact parameters more than twice the nuclear radius, so hadronic interactions are suppressed. These events also provide an ideal proving ground for new programs in e$+$A physics. We present recent results from the J/$\psi $ photo-production measurement using 200GeV Au$+$Au collisions in the STAR experiment at RHIC. The p$_{\mathrm{T}}$ distribution of the J/$\psi $ mesons peaks at very low p$_{\mathrm{T}}$, consistent with expectations for coherent photo-production. Because of its heavy mass, the J/$\psi $ meson has sufficient virtuality to probe the Au wave function deeply enough to discern the possible presence of gluon shadowing. We will present the measurement of J/$\psi $ cross section in 200GeV Au$+$Au collisions, as well as a distribution of J/$\psi $ rapidity within $|y| < 1$. Possible theory comparisons are also discussed. [Preview Abstract] |
Friday, November 8, 2013 10:54AM - 11:06AM |
C1.00003: Evidence of Narrow Structure in the J/$\psi \phi$ Mass Spectrum in Exclusive $B^{+} \rightarrow J/\psi \phi K^{+}$ decay at CMS Maksat Haytmyradov Analysis of heavy quarkonium states provides an effective method to test QCD predictions. Recent studies on these mesons show that there are states which have decay modes similar to charmonium, but are difficult to put in a charmonium system. There have been several proposals explaining these states as hybrid($q\bar{q}g$) or four-quark ($q\bar{q}q\bar{q}$) exotic mesons. Discoveries such as the X(3872) and Y(3940) motivated examination of other VV states. Observation of Y(4140) at CDF detector further inspired to search for the same structure at CMS detector. In this analysis the $J/\psi \phi$ channel was studied through the exclusive decay of $B^{\pm} \rightarrow J/\psi \phi K^{\pm}$, where $J/\psi \rightarrow \mu^{-} \mu^{+}$ and $\phi \rightarrow K^{+} K^{-}$. The analysis was conducted on pp collision data at $\sqrt(s)$ = 7TeV collected by the CMS detector. We report on two narrow structures with masses around 4148 and 4317 GeV in $J/\psi \phi$ mass spectrum which are well above the threshold for $c\bar{c}$ charmonium decays. [Preview Abstract] |
Friday, November 8, 2013 11:06AM - 11:18AM |
C1.00004: Optimizing the Monte Carlo Simulation for the DarkSide Detector Matthew Smallcomb, Andrew Alton My goal was to test and help optimize the new Monte Carlo simulator being developed by Davide Franco of the DarkSide collaboration. Developing a robust optical simulation of the Darkside-50 detector is essential for understanding the behavior of background events and is necessary for showing proof of concepts in order to procure funding for the project. I spent the summer looking at reproducing event positions from simulation data and comparing detector data and simulation results of the ratio between light detected on the top and bottom photomultiplier tubes. Testing showed that there were some critical changes that need to be implemented in the simulation. [Preview Abstract] |
Friday, November 8, 2013 11:18AM - 11:30AM |
C1.00005: The Muon Charge Asymmetry Measurement in Inclusive pp$\rightarrow$W+X production at $\sqrt{s}$=7 TeV Hasan Ogul Measurements of the muon charge asymmetry in inclusive pp$\rightarrow$W+X production at $\sqrt{s}$=7 TeV are presented. The data sample corresponds to an integrated luminosity of 4.7 $\mathrm{fb}^{-1}$ recorded by the CMS detector at the LHC. With a sample of more than 20 million $\mathrm{W}\rightarrow \mu\nu$ events, the statistical precision is greatly improved in comparison to previous measurements. These new results provide additional constraints on the parton distribution functions of the proton in the Bjorken parameter $x$ range from 0.001 to 0.1. [Preview Abstract] |
Friday, November 8, 2013 11:30AM - 11:42AM |
C1.00006: Comparative study of nonperturbative heavy quarks in the nucleon Timothy Hobbs, John Londergan, Wally Melnitchouk We perform an analysis of the role of nonperturbative (or intrinsic) charm in the nucleon. Charm is generated nonperturbatively through Fock state expansions of the nucleon wave function to include five-quark virtual states involving charmed mesons and baryons. We consider contributions from a variety of charmed meson-baryon states and find surprisingly dominant effects from the $\bar{D}^{* 0}\, \Lambda_c^+$ configuration. Particular attention is paid to the existence and persistence of high-$x$ structure for intrinsic charm, and the $x$ dependence of the $c-\bar c$ asymmetry predicted in meson-baryon models. We also discuss efforts to constrain intrinsic charm via a forthcoming global QCD analysis, and the possibility of extracting intrinsic strangeness using a similar approach. [Preview Abstract] |
Friday, November 8, 2013 11:42AM - 11:54AM |
C1.00007: Searches for possible T-odd and P-odd short range interactions using polarized nuclei Rakshya Khatiwada, Pinghan Chu, Alec Dennis, Changbo Fu, Haiyan Gao, Georgios Laskaris, Ke Li, Erick Smith, William Snow, Haiyang Yan, Wangzhi Zheng Various theories predict the possible existence of T-odd and P-odd short-range forces between spin-$1/2$ fermions, proportional to $\mathbf{S} \cdot \mathbf{r}$ where $\mathbf{S}$ is the fermion spin and $\mathbf{r}$ is the separation between particles. We use ensembles of polarized nuclei and an unpolarized mass to search for such a force over sub-mm ranges. We established an improved upper bound on the product $g_s g_p^n$ of the scalar coupling to particles in the unpolarized mass and the pseudo-scalar coupling of polarized neutrons for force ranges from $10^{-4}$ to $10^{-2}$ m, corresponding to a mass range of 2 $\cdot$ 10$^{-3}$ to 2 $\cdot$ 10$^{-5}$ eV for the exchange boson. [Preview Abstract] |
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