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Title: Supersymmetry-induced flavor-changing neutral-current top-quark processes at the CERN Large Hadron Collider

Abstract

We systematically calculate various flavor-changing neutral-current top-quark processes induced by supersymmetry at the Large Hadron Collider, which include five decay modes and six production channels. To reveal the characteristics of these processes, we first compare the dependence of the rates for these channels on the relevant supersymmetric parameters, then we scan the whole parameter space to find their maximal rates, including all the direct and indirect current experimental constraints on the scharm-stop flavor mixings. We find that, under all these constraints, only a few channels, through cg{yields}t at parton level and t{yields}ch, may be observable at the Large Hadron Collider.

Authors:
;  [1]; ;  [2];  [3];  [4];  [5]
  1. Physics Department, Technion, 32000 Haifa (Israel)
  2. Department of Physics, Concordia University, Montreal, H4B 1R6 (Canada)
  3. Department of Physics, Tohoku University, Sendai 980-8578 (Japan)
  4. Service de Physique Theorique CP225, Universite Libre de Bruxelles, 1050 Brussels (Belgium)
  5. Institute of Theoretical Physics, Academia Sinica, Beijing 100080 (China)
Publication Date:
OSTI Identifier:
21020315
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 75; Journal Issue: 7; Other Information: DOI: 10.1103/PhysRevD.75.075021; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; C QUARKS; CERN LHC; COMPARATIVE EVALUATIONS; FLAVOR MODEL; GLUONS; NEUTRAL CURRENTS; PARTICLE DECAY; QUARK-GLUON INTERACTIONS; SUPERSYMMETRY; T QUARKS

Citation Formats

Cao, J. J., Eilam, G., Frank, M., Turan, I., Hikasa, K., Liu, G. L., and Yang, J. M. Supersymmetry-induced flavor-changing neutral-current top-quark processes at the CERN Large Hadron Collider. United States: N. p., 2007. Web. doi:10.1103/PHYSREVD.75.075021.
Cao, J. J., Eilam, G., Frank, M., Turan, I., Hikasa, K., Liu, G. L., & Yang, J. M. Supersymmetry-induced flavor-changing neutral-current top-quark processes at the CERN Large Hadron Collider. United States. doi:10.1103/PHYSREVD.75.075021.
Cao, J. J., Eilam, G., Frank, M., Turan, I., Hikasa, K., Liu, G. L., and Yang, J. M. Sun . "Supersymmetry-induced flavor-changing neutral-current top-quark processes at the CERN Large Hadron Collider". United States. doi:10.1103/PHYSREVD.75.075021.
@article{osti_21020315,
title = {Supersymmetry-induced flavor-changing neutral-current top-quark processes at the CERN Large Hadron Collider},
author = {Cao, J. J. and Eilam, G. and Frank, M. and Turan, I. and Hikasa, K. and Liu, G. L. and Yang, J. M.},
abstractNote = {We systematically calculate various flavor-changing neutral-current top-quark processes induced by supersymmetry at the Large Hadron Collider, which include five decay modes and six production channels. To reveal the characteristics of these processes, we first compare the dependence of the rates for these channels on the relevant supersymmetric parameters, then we scan the whole parameter space to find their maximal rates, including all the direct and indirect current experimental constraints on the scharm-stop flavor mixings. We find that, under all these constraints, only a few channels, through cg{yields}t at parton level and t{yields}ch, may be observable at the Large Hadron Collider.},
doi = {10.1103/PHYSREVD.75.075021},
journal = {Physical Review. D, Particles Fields},
number = 7,
volume = 75,
place = {United States},
year = {Sun Apr 01 00:00:00 EDT 2007},
month = {Sun Apr 01 00:00:00 EDT 2007}
}
  • We examine experimental constraints on scharm-stop flavor mixing in the minimal supersymmetric standard model, which arise from the experimental bounds on squark and Higgs boson masses, the precision measurements of W-boson mass and the effective weak mixing angle, as well as the experimental data on B{sub s}-B{sub s} mixing and b{yields}s{gamma}. We find that the combined analysis can put rather stringent constraints on c-tilde{sub L}-t-tilde{sub L} and c-tilde{sub L}-t-tilde{sub R} mixings. As an illustration for the effects of such constraints, we examine various top-quark flavor-changing neutral-current processes induced by scharm-stop mixings at the LHC and find that their maximal ratesmore » are significantly lowered.« less
  • We study extensions of the standard model with additional colored scalar fields which can couple directly to quarks. Natural suppression of flavor changing neutral currents implies minimal flavor violation, and fixes the scalars to transform as (8,2){sub 1/2} under the SU(3)xSU(2)xU(1) gauge symmetry. We explore the phenomenology of the standard model with one additional (8,2){sub 1/2} scalar, and discuss how this extension can modify flavor physics and the Higgs boson production rate at the LHC. Custodial SU(2) symmetry can be implemented for the octet scalars since they transform as a real color representation. Additional weak scale degrees of freedom neededmore » for gauge unification are discussed.« less
  • We study the combined effects of both strong and electroweak dimension six effective operators on flavor changing top quark physics at the CERN LHC. Analytic expressions for the cross sections and decay widths of several flavor changing processes will be presented, as well as an analysis of the feasibility of their observation at the LHC.
  • We present the calculations of the complete next-to-leading order (NLO) QCD effects on the single top productions induced by model-independent tqg flavor-changing neutral-current couplings at hadron colliders. Our results show that, for the tcg coupling, the NLO QCD corrections can enhance the total cross sections by about 60% and 30%, and for the tug coupling by about 50% and 20% at the Tevatron and LHC, respectively, which means that the NLO corrections can increase the experimental sensitivity to the flavor-changing neutral-current couplings by about 10%-30%. Moreover, the NLO corrections reduce the dependence of the total cross sections on the renormalizationmore » or factorization scale significantly, which lead to increased confidence on the theoretical predictions. Besides, we also evaluate the NLO corrections to several important kinematic distributions, and find that for most of them the NLO corrections are almost the same and do not change the shape of the distributions.« less
  • We show that supersymmetric {ital R}-parity-breaking ({ital R/}{sub {ital p}}) interactions always result in flavor changing neutral current processes. Within a single coupling scheme, these processes can be avoided in either the charge +2/3 or the charge {minus}1/3 quark sector, but not both. These processes are used to place constraints on {ital R/}{sub {ital p}} couplings. The constraints on the first and the second generations are better than those existing in the literature. The {ital R/}{sub {ital p}} interactions may result in new top quark decays. Some of these violate electron-muon universality or produce a surplus of {ital b} quarkmore » events in {ital t{bar t}} decays. Results from the CDF experiment are used to bound these {ital R/}{sub {ital p}} couplings. {copyright} {ital 1996 The American Physical Society.}« less