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Title: The Search for New Physics in Di-Electron Events at CDF

Abstract

A narrow resonance resulting from a new physics process is searched in the dielectron channel using approximately 819 pb -1 of Tevatron proton-antiproton collision data at √s = 1.96 TeV.

Authors:
 [1]
  1. New College, Oxford (United Kingdom)
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1369236
Report Number(s):
FERMILAB-THESIS-2007-103
1516536
DOE Contract Number:
AC02-07CH11359
Resource Type:
Thesis/Dissertation
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats

Harper, Sam. The Search for New Physics in Di-Electron Events at CDF. United States: N. p., 2007. Web. doi:10.2172/1369236.
Harper, Sam. The Search for New Physics in Di-Electron Events at CDF. United States. doi:10.2172/1369236.
Harper, Sam. Mon . "The Search for New Physics in Di-Electron Events at CDF". United States. doi:10.2172/1369236. https://www.osti.gov/servlets/purl/1369236.
@article{osti_1369236,
title = {The Search for New Physics in Di-Electron Events at CDF},
author = {Harper, Sam},
abstractNote = {A narrow resonance resulting from a new physics process is searched in the dielectron channel using approximately 819 pb-1 of Tevatron proton-antiproton collision data at √s = 1.96 TeV.},
doi = {10.2172/1369236},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

Thesis/Dissertation:
Other availability
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  • This thesis presents the results of a signature-based search for new physics using the exclusive dijet plus missing transverse energy data sample from 2 fb -1 pmore » $$\bar{p}$$ collisions at √s = 1.96 TeV collected from the Collider Detector at Fermilab (CDF). A study is made of the production of events with two high energy jets and large missing transverse energy (missing E T, or E T) in a kinematic regime requiring the scalar sum of the E T of the two jets (referred to here as H T) to be greater than 125 GeV and the event E T to be above 80 GeV. A second kinematic region is also examined, with the E T cut increased to 100 GeV and the H T cut increased to 225 GeV. The number of events observed in the data is within 0.43 standard deviations of the expected number of background events in the low kinematic region, and with 0.34 standard deviations in the high kinematic region. Based on these results, 95% C.L. lower mass limits for scalar leptoquarks are extracted: 190 GeV/ c 2 for 1st generation, 190 GeV/ c 2 for 2nd generation, and 178 GeV/ c 2 for 3rd generation production. The results are also interpreted in terms of cross-section limits on generic minimal supersymmetric (MSSM) models.« less
  • We present a search for physics beyond the standard model (SM) through a measurement of the violation of the charge-parity (CP) symmetry in two decays of the B 0 2 meson using data collected by the Collider Detector at Fermilab (CDF) in proton-antiproton collisions at the center-of-mass energy of 1.96TeV. We exploit the decays B 0 2→J/Ψ(→ μ +μ -)(→ K +K -) and B 0 2→Φ (→ K +K -)Φ(→ K +K -), for which the SM accurately predicts very small or vanishing CP violation; both decay modes are very sensitive to new sources of CP violation expected inmore » a broad class of SM extensions. We analyze the time-dependent CP asymmetry of the B 0 2→J/ΨΦ decays collected in the full CDF Run II dataset for providing the final measurement of the B 0 2 -¯B 0 2 mixing phase, 2β s, and we present the first measurement of CP violation in B 0 2→ΦΦ decays, through the determination of two time-integrated CP asymmetries, A v and A u, using an original method developed in this work. We find: -0.06 < β s < 0.30 at the 68% confidence level; A v = (-12.0 ± 6.4(stat) ± 1.6(syst))%; and A u = (-0.7 ± 6.4(stat) ± 1.8(syst))%. In addition, we provide measurements of the decay width difference between the light and heavy mass eigenstates of the B 0 2 meson,ΔΓ s 0.068 ± 0.026(stat) ± 0.009(syst) ps -1; and of their mean lifetime, τ s = 1.528 ± 0.019(stat) ± 0.009(syst) ps. All results are among the most precise determinations from a single experiment and exhibit an excellent agreement with the SM predictions.« less
  • We present the results of a search for new particles decaying to tau pairs using the data corresponding to an integrated luminosity of 195 pb -1 collected from March 2002 to September 2003 with the CDF detector at the Tevatron. Hypothetical particles, such as Z' and MSSM Higgs bosons can potentially produce the tau pair final state. We discuss the method of tau identification, and show the signal acceptance versus new particle mass. The low-mass region, dominated by Z → ττ, is used as a control region. In the high-mass region, we expect 2.8 ± 0.5 events from known backgroundmore » sources, and observe 4 events in the data sample. Thus no significant excess is observed, and we set upper limits on the cross section times branching ratio as a function of the masses of heavy scalar and vector particles.« less
  • We present the results of a search in pmore » $$\bar{b}$$ collisions at √s = 1.8 TeV for anomalous production of events containing a photon with large transverse energy and a lepton (e or μ) with large transverse energy, using 86 pb -1 of data collected at the Collider Detector at Fermilab during the 1994-95 collider run at the Fermilab Tevatron. The presence of large missing transverse energy (E T), additional photons, or additional leptons in these events is also analyzed. The results are consistent with standard model expectations, with the possible exception of photon-lepton events with large E T, for which the probability of a statistical fluctuation of the standard model expectation up to and above the observed level is 0.7%.« less
  • The authors have searched for new physics beyond the Standard Model of elementary particle physics in dielectron decay mode at the CDF (Collider Detector at Fermilab) experiment in {bar p}p collisions at √s = 1.96 TeV. The data were collected during the 2002-2003 runs corresponding to an integrated luminosity of 200 pb -1. Many extensions of the Standard Model have been proposed. Grand Unified Theories (GUT) assumes a larger gauge symmetry group and predict new gauge bosons. GUT has hierarchy problem in it and there have been many attempts to solve the hierarchy problem. Solutions for the hierarchy problem aremore » supersymmetry, technicolor, large extra dimensions, warped extra dimensions and little Higgs models. The authors analyze the differential distribution of dielectron events in terms of their invariant mass and no significant excess is found in very high mass region. They present a 95% confidence level limit on the production cross section times branching ratio for new resonant particles decaying into an electron pair as a function of invariant mass. New resonant particles include new neutral gauge boson Z', Randall-Sundrum graviton, R-parity violating sneutrino, and technicolor particles. They also present limits on the effective Planck scale of large extra dimensions.« less