Search for R-parity Violating Decays of a Top Squark in Proton{u2013}proton Collisions at


Book Description

The results of a search for a supersymmetric partner of the top quark (top squark), pair-produced in proton-proton collisions at $\sqrt{s} =$ 8 TeV, are presented. The search, which focuses on R-parity violating, chargino-mediated decays of the top squark, is performed in final states with low missing transverse momentum, two oppositely charged electrons or muons, and at least five jets. The analysis uses a data sample corresponding to an integrated luminosity of 19.7 fb${̂-1}$ collected with the CMS detector at the LHC in 2012. The data are found to be in agreement with the standard model expectation, and upper limits are placed on the top squark pair production cross section at 95% confidence level. Assuming a 100% branching fraction for the top squark decay chain, $ \mathrm{ \tilde{t} \to t \tilde{\chi}{̂\pm}_1,\, \tilde{\chi}{̂\pm}_1 \to \ell\̂pm+jj } $, top squark masses less than 890 (1000) GeV for the electron (muon) channel are excluded for the first time in models with a single nonzero R-parity violating coupling $\lambda{̂\prime}_{ijk}$ $(i,j,k \leq 2)$, where $i,j,k$ correspond to the three generations.




Search for R-parity Violating Supersymmetry in Multilepton Final States Using the ATLAS Detector


Book Description

This thesis presents a search for R-parity violating supersymmetry at sqrt(s)=13 TeV, using approximately 13.3 fb-1 of data collected by ATLAS in 2015 and the first half of 2016. Events are required to contain at least four leptons (electrons or muons only) that are not the product of a Z boson decay, and this requirement results in a low Standard Model background and a high sensitivity to various physics models beyond the Standard Model. No significant deviations from the Standard Model are observed in data, and results are used to set upper limits on the event yields from processes beyond the Standard Model. In a simplified model of chargino production with indirect R-parity violating decays, limits are extended by approximately 400 GeV relative to the Run 1 search, excluding chargino masses below 1.1 TeV.




Search for R-parity Violating Decays of a Top Squark in Proton-proton Collisions at $\sqrt{s}$


Book Description

The results of a search for a supersymmetric partner of the top quark (top squark), pair-produced in proton-proton collisions at $\sqrt{s} =$ 8 TeV, are presented. The search, which focuses on R-parity violating, chargino-mediated decays of the top squark, is performed in final states with low missing transverse momentum, two oppositely charged electrons or muons, and at least five jets. The analysis uses a data sample corresponding to an integrated luminosity of 19.7 fb$^{-1}$ collected with the CMS detector at the LHC in 2012. The data are found to be in agreement with the standard model expectation, and upper limits are placed on the top squark pair production cross section at 95% confidence level. Assuming a 100% branching fraction for the top squark decay chain, $ \mathrm{ \tilde{t} \to t \tilde{\chi}^{\pm}_1,\, \tilde{\chi}^{\pm}_1 \to \ell^\pm+jj } $, top squark masses less than 890 (1000) GeV for the electron (muon) channel are excluded for the first time in models with a single nonzero R-parity violating coupling $\lambda^{\prime}_{ijk}$ $(i, j, k \leq 2)$, where $i, j, k$ correspond to the three generations.




Search for R-parity Violating Decays of a Top Squark in Proton-proton Collisions at [mml


Book Description

Here, the results of a search for a supersymmetric partner of the top quark (top squark), pair-produced in proton-proton collisions at √s = 8 TeV, are presented. The search, which focuses on R-parity violating, chargino-mediated decays of the top squark, is performed in final states with low missing transverse momentum, two oppositely charged electrons or muons, and at least five jets. The analysis uses a data sample corresponding to an integrated luminosity of 19.7 fb-1 collected with the CMS detector at the LHC in 2012. The data are found to be in agreement with the standard model expectation, and upper limits are placed on the top squark pair production cross section at 95% confidence level. Assuming a 100% branching fraction for the top squark decay chain, t~→t[chi]~1±,[chi]~1± → l± + jj, top squark masses less than 890 (1000) GeV for the electron (muon) channel are excluded for the first time in models with a single nonzero R-parity violating coupling [lambda]ijk'(i,j,k ≤ 2), where i,j,k correspond to the three generations.







Lepton Dipole Moments


Book Description

This book provides a self-contained description of the measurements of the magnetic dipole moments of the electron and muon, along with a discussion of the measurements of the fine structure constant, and the theory associated with magnetic and electric dipole moments. Also included are the searches for a permanent electric dipole moment of the electron, muon, neutron and atomic nuclei. The related topic of the transition moment for lepton flavor violating processes, such as neutrinoless muon or tauon decays, and the search for such processes are included as well. The papers, written by many of the leading authors in this field, cover both the experimental and theoretical aspects of these topics. Sample Chapter(s). Chapter 1: Historical Introduction to Electric and Mangnetic Moments (367 KB). Contents: Historical Introduction (B L Roberts); Electromagnetic Dipole Moments and New Physics (A Czarnecki & W J Marciano); Lepton g OCo 2 from 1947 to Present (T Kinoshita); Analytic QED Calculations of the Anomalous Magnetic Moment of the Electron (S Laporta & E Remiddi); Measurements of the Electron Magnetic Moment (G Gabrielse); Determining the Fine Structure Constant (G Gabrielse); Helium Fine Structure Theory for the Determination of (K Pachucki & J Sapirstein); Hadronic Vacuum Polarization and the Lepton Anomalous Magnetic Moments (M Davier); The Hadronic Light-by-Light Contribution to a, e (J Prades et al.); General Prescriptions for One-loop Contributions to a e, (K R Lynch); Measurement of the Muon ( g OCo 2) Value (J P Miller et al.); Muon ( g OCo 2) and Physics Beyond the Standard Model (D StAckinger); Probing CP Violation with Electric Dipole Moments (M Pospelov & A Ritz); The Electric Dipole Moment of the Electron (E D Commins & D DeMille); Neutron EDM Experiments (S K Lamoreaux & R Golub); Nuclear Electric Dipole Moments (W C Griffith et al.); EDM Measurements in Storage Rings (B L Roberts et al.); Models of Lepton Flavor Violation (Y Okada); Search for the Charged Lepton-Flavor-Violating Transition Moments l OaAE l OC (Y Kuno). Readership: Researchers and graduate students in particle physics, atomic physics and nuclear physics, as well as experts working in the field













Weak Scale Supersymmetry


Book Description

This OA text develops the basic concepts of supersymmetry for experimental and phenomenological particle physicists and graduate students.