Session HB: Particle Physics I

Search for the Standard Model Higgs boson decaying to $\mu^+\mu^-$ in $pp$ collisions at $\sqrt{s}=$7 and 8 TeV with the CMS detector

A search for the standard model Higgs boson in the rare $\mu^+\mu^-$ decay channel is presented. The data samples, recorded by the CMS experiment at the LHC, correspond to integrated luminosities of $5.0\pm0.1$ fb$^{-1}$ at 7 TeV center-of-mass energy and of $19.7\pm0.5$ fb$^{-1}$ at 8 TeV. To enhance the Higgs signal over the dominant Drell-Yan background, the events are categorized by topologies corresponding to different production processes. Upper limits on the production rate, with respect to the Standard Model prediction, are reported at the 95\% confidence level for Higgs boson masses in the range from 115 to 155 GeV/c$^2$.   

Recent development on the Daya Bay reactor neutrino experiment

The Daya Bay Reactor Neutrino Experiment has been very successful in unveiling the last unknown mixing angle using multiple detectors at various baselines with a designed 90{\%} C.L. sensitivity of Sin$^2$(2$\theta_{13}$) \textless~0.01. The experiment is now running in its full 8 antineutrino detectors configuration and effort is focused on finalizing the 6-detector rate and shape analysis. This talk will focus on an analysis to extract the antineutrino energy spectra of the four major reactor fissionable isotopes based on different reactor burn-up periods in the Daya Bay data set.   

The Study of Neutrino Properties from Dark Matter Annihilations in the Sun

NOvA (NuMI Off-Axis ve Appearance) is an experiment studying a neutrino beam sent from Fermilab to northern Minnesota. The main goal of NOvA is to observe neutrino oscillations. NOvA can also be used for many other different experiments. We use upward-going muons to investigate the possibility of dark matter in the center of Sun. Weakly Interacting Massive Particles (WIMPs) are currently the main candidates for dark matter. We have been studying neutrino propagations from annihilations of WIMPS at the core of the Sun. WIMPSIM is a program that simulates WIMP annihilations in the Sun and then propagates the resulting neutrinos to the surface of the Earth. The data from WIMPSIM helps us study angular acceptance of neutrino yields. This will give us a better understanding of upward-going muons so we can more easily recreate them in a toy Monte Carlo.   

Searches for New Physics using $Z\gamma$ and Z$\gamma$$\gamma$ production at the LHC

High energy photons produced in association with Z bosons are measured using $pp$ collisions at $\sqrt{s}$ = 8 TeV. The analyses use a data sample with an integrated luminosity of 20.3 $fb^{-1}$ collected by the ATLAS detector during 2013 LHC data taking. Events are selected using leptonic decays of Z bosons ($Z$($e^+$$e^-$, $\mu^+$$\mu^-$)) with the requirement of an associated isolated photon with transverse energy greater than 15 GeV. The data are used to test the electroweak sector of the Standard Model and search for evidence of new phenomena. Further, the measurements are used to set limits on anomalous triple and quartic Z$\gamma$ and Z$\gamma$$\gamma$ guage couplings.   

Identification of Upward-going Muons for Dark Matter Searches at the NOvA Experiment

We search for energetic neutrinos that could originate from dark matter particles annihilating in the core of the Sun using the newly built NOvA Far Detector at Fermilab. Only upward-going muons produced via charged-current interactions are selected as signal in order to eliminate backgrounds from cosmic ray muons, which dominate the downward-going flux. We investigate several algorithms so as to develop an effective way of reconstructing the directionality of cosmic tracks at the trigger level. These studies are a crucial part of understanding how NOvA may compete with other experiments that are performing similar searches. In order to be competitive, NOvA must be capable of rejecting backgrounds from downward-going cosmic rays with very high efficiency while accepting most upward-going muons.   

Quantum Electrodynamics Interpolated Between Instant Form and Front Form

Among the three forms of relativistic dynamics proposed by Dirac in1949, the front form of relativistic dynamics now known as the light-front dynamics (LFD) appears to have definite advantages over the instant form dynamics, when it deals with the hadronic processes where the relativistic effects are significant. In particular, LFD may save a substantial dynamical effort put in the instant form dynamics with respect to getting the QCD solutions that reflect the full Poincar\'e symmetries, due to the built-in boost invariance and simpler vacuum property. As an effort to understand how the familiar instant form dynamics (IFD) transforms to LFD, we interpolate the two forms of dynamics by introducing an interpolation angle that changes the ordinary time $t$ to light front time $(t+z/c)\sqrt{2}$. In this presentation, we report our derivation of the polarization vectors for photon and the helicity spinors for spin-1/2 fermion that interpolate between IFD and LFD and the application of our results to the lowest-order QED scattering amplitudes. Our analysis makes clear the distinction between the infinite momentum frame (IMF) and the LFD.