Bulletin of the American Physical Society
APS April Meeting 2015
Volume 60, Number 4
Saturday–Tuesday, April 11–14, 2015; Baltimore, Maryland
Session H16: Strong Interaction and Hadron Physics |
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Sponsoring Units: DPF Chair: Sally Seidel, University of New Mexico Room: Key 12 |
Sunday, April 12, 2015 8:30AM - 8:42AM |
H16.00001: Search for diboson resonances with jets in 20fb$^{-1}$ of $pp$ collisions at $\sqrt[]{s}=8$ TeV with the ATLAS detector Angel Campoverde ATLAS data coming from 2012 8 TeV pp collisions are used to search for narrow diboson resonances in a dijet final state, where each jet is identified as originating from the hadronic decay of a W or Z boson. The hadronic final state offers the highest branching ratio but it also has a huge QCD dijet background associated; to cope with it the analysis utilizes substructure within jets to identify diboson events. A data driven estimate of the background is used and any sign of new physics is expected as an excess of events in a smoothly falling dijet mass spectrum. The results are interpreted in terms of W$'$ bosons and Kaluza-Klein excitations of the graviton in the Randall-Sundrum model. [Preview Abstract] |
Sunday, April 12, 2015 8:42AM - 8:54AM |
H16.00002: Measurement of the triple differential cross section for direct photon plus jet production with the CMS detector Ajeeta Khatiwada We measure the triple differential cross section for direct photon plus jet as a function of photon transverse momentum, photon pseudorapidity, and jet pseudorapidity. The production of direct photons in association with jets can be used to understand gluon distribution functions as well as to test perturbative Quantum Chromodynamics at wide kinematic range of hard-scattering scales ($Q^2$) and parton momentum fractions ($x$). The measurement is made using single-photon-triggered dataset collected by the Compact Muon Solenoid detector in proton-proton collisions. [Preview Abstract] |
Sunday, April 12, 2015 8:54AM - 9:06AM |
H16.00003: Phase space generator for the initial state radiation in the P P interaction Essma Redouane Salah, Christian Bauer, Marjorie Shapiro An efficient phase space integration is important for most calculations for collider experiments. Using the Altarelli-Parisi splitting functions as the underlying probability for a splitting, we developed a phase space generator that distribute phase space points according to the singular limit of QCD. [Preview Abstract] |
Sunday, April 12, 2015 9:06AM - 9:18AM |
H16.00004: An analytic determination of the gluon distribution function from HERA combined data for the proton structure function $F_2^{\gamma p}(x,Q^2)$ Phuoc Ha We exploit a new method based on Laplace transforms to find an exact analytic solution of the leading-order (LO) gluon distribution function $G(x,Q^2)=xg(x,Q^2)$ directly from the proton structure function $F_2^{\gamma p}(x,Q^2)$. The method uses only the LO DGLAP evolution equation for $F_2^{\gamma p}(x,Q^2)$ without making any assumptions about the shape of the low $x$ gluon distributions. Using an accurate, new global parametrization of the complete set of low Bjorken-$x$ HERA data on $F_2^{\gamma p}(x,Q^2)$, including the data at very low $Q^2$, we determine the gluon distribution $G(x,Q^2)$ for massless quarks and compare our results to other published gluon distributions. An extension of the present method to determine the NLO corrections to the gluon distributions is also presented. [Preview Abstract] |
Sunday, April 12, 2015 9:18AM - 9:30AM |
H16.00005: An Intimate Relationship between Higgs Forces, Dark Matter, and Dark Energy Antonio Colella Our universe's 8 permanent matter particles were: up quark, down quark, electron, electron-neutrino, muon-neutrino, tau-neutrino, zino, and photino. Zino and photino were dark matter particles. Each permanent matter particle had an associated supersymmetric Higgs force. Sum of the 8 Higgs force energies was dark energy. Amplifications of Higgs theory included: 16 SM matter/force particles, 16 superpartners, 32 anti-particles, and 64 associated supersymmetric Higgs particles; 17 Higgs forces and 15 Higgsinos; Higgs force was a residual super force; Matter particles and associated Higgs forces were one and inseparable and modeled as underweight porcupine with overgrown spines; Mass given to a matter particle via associated Higgs force and gravitational force messenger particles; Super force condensed into 17 matter/Higgs forces at 17 extremely high temperatures; 9 transient matter particles/Higgs forces evaporated to super force and condensed to 8 permanent matter particles/Higgs forces (decay); Spontaneous symmetry breaking was bidirectional; Matter/Higgs force creation was time synchronous with inflation and one to seven Planck cubes energy to matter expansion; 128 matter/force particles required for Conservation of Energy/Mass accountability at t $=$ 100s. [Preview Abstract] |
Sunday, April 12, 2015 9:30AM - 9:42AM |
H16.00006: Double Parton Interactions in $2\gamma + 2$ jets events in $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV at D0 George Golovanov We use a sample of diphoton + dijet events collected by the D0 detector in a data sample corresponding to an integrated luminosity of about 8.7 fb$^{-1}$ of $p\bar{p}$ collisions at the Fermilab Tevatron collider, to study properties of events with double-parton scattering (DPS) in single $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV. We describe the measurement of the DPS event fraction, the effective cross section ($\sigma_{\mathrm{eff}}$), for double-parton scattering [Preview Abstract] |
Sunday, April 12, 2015 9:42AM - 9:54AM |
H16.00007: Jet vetoes versus giant K-factors in the exclusive Z+1-jet cross section Christfried Focke, Radja Boughezal, Xiaohui Liu The ATLAS measurement of the exclusive Z+1-jet cross section shows a surprising agreement with fixed-order predictions in the kinematic region expected to be dominated by large jet-veto logarithms. We identify the explanation for this effect: the jet-isolation criterion implemented by ATLAS allows dijet events where an energetic jet is collinear to a final-state lepton. This process contains a giant $K$-factor arising from the collinear emission of a Z-boson from the dijet configuration which overwhelms the effect of the jet-veto logarithms. We provide numerical results for $7~TeV$, $8~TeV$ and $14~TeV$ LHC collisions that demonstrate the interplay between the jet-veto logarithms and the giant $K$-factor in the theoretical prediction. We suggest an alternate isolation criterion that removes the giant $K$-factor and allows for a direct test of the jet-veto resummation framework in the Z+1-jet process. [Preview Abstract] |
Sunday, April 12, 2015 9:54AM - 10:06AM |
H16.00008: Aspects regarding decay of superfluid vortices in dense quark matter S Kumar Mallavarapu, Mark Alford It has been mentioned in current literature that the so called superfluid vortices/strings in high density color flavor locked phase of dense quark matter might be unstable. A regular superfluid string could decay into more fundamental strings known as semi-superfluid strings. Each semi-superfluid string has a non-zero color flux. It has been calculated that a combination of three such semi-superfluid strings which have zero net color flux is more stable than a single superfluid string, so long as the separation between the semi-superfluid strings is much larger than the size of each one. Is the semi-superfluid string configuration more stable than the superfluid string even for small separations? Does the single superfluid string spontaneously break into semi-superfluid strings? In this talk we offer results and insight that would help us answer these questions. [Preview Abstract] |
Sunday, April 12, 2015 10:06AM - 10:18AM |
H16.00009: Study of the Sensitivity for Searches for Excited Boson ($W^*$) in Dijet Final States in proton-proton collisions at $\sqrt{s}=13$ TeV with the ATLAS Detector at the LHC Jaryd Ulbricht, Harinder Bawa, Yongsheng Gao The recent Large Hadron Collider (LHC) beam upgrade in center-of-mass energy from $\sqrt{s} = 8$ TeV to $\sqrt{s} = 13$ TeV has required upgrades to the Monte Carlo simulations used to search for new physics in the dijet final state. Monte Carlo simulation studies are performed, using as a baseline for a new physics signal excited bosons ($W^*$) with resonant masses ranging from $200$-$4000$ GeV. The samples are validated by comparing kinematics at various center-of-mass energies and by using different parton distribution functions. The sensitivity for observing or setting limits on a $W^*$ signal is also studied. [Preview Abstract] |
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