Top quark Kaluza-Klein mode mixing in the Randall-Sundrum bulk standard model and B→Xsγ

Choong Sun Kim, J. D. Kim, Jeonghyeon Song

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

We study top quark Kaluza-Klein (KK) mode mixing in the Randall-Sundrum scenario with all the SM fermions and gauge bosons in the bulk. Even though the simple assumption of a universal bulk fermion mass mψ leads to the same KK mass spectrum for all SM fermions and thus suppresses new contributions to the flavor changing neutral current and the ρ parameter, the large Yukawa coupling of the top quark generates mixing among its KK modes and breaks the degeneracy: An unacceptably large contribution to Δρ occurs. In order to satisfy the Δρ constraint, we relax the model by assigning a different bulk fermion mass to the SU(2) singlet bottom quark and demonstrate that there exists some limited parameter space where the Δρ constraint is satisfied. It is also shown that the current measurement of Br(B→Xs+γ) can be accommodated in this modified model, and the one sigma level precision constrains the effective weak scale kEW such as kEW ≳3. TeV for mψ/k= -0.4, where kEW is the warp-suppressed AdS5 curvature.

Original languageEnglish
Article number015001
JournalPhysical Review D
Volume67
Issue number1
DOIs
Publication statusPublished - 2003 Dec 1

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fermions
quarks
neutral currents
mass spectra
bosons
curvature

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)

Cite this

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abstract = "We study top quark Kaluza-Klein (KK) mode mixing in the Randall-Sundrum scenario with all the SM fermions and gauge bosons in the bulk. Even though the simple assumption of a universal bulk fermion mass mψ leads to the same KK mass spectrum for all SM fermions and thus suppresses new contributions to the flavor changing neutral current and the ρ parameter, the large Yukawa coupling of the top quark generates mixing among its KK modes and breaks the degeneracy: An unacceptably large contribution to Δρ occurs. In order to satisfy the Δρ constraint, we relax the model by assigning a different bulk fermion mass to the SU(2) singlet bottom quark and demonstrate that there exists some limited parameter space where the Δρ constraint is satisfied. It is also shown that the current measurement of Br(B→Xs+γ) can be accommodated in this modified model, and the one sigma level precision constrains the effective weak scale kEW such as kEW ≳3. TeV for mψ/k= -0.4, where kEW is the warp-suppressed AdS5 curvature.",
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Top quark Kaluza-Klein mode mixing in the Randall-Sundrum bulk standard model and B→Xsγ. / Kim, Choong Sun; Kim, J. D.; Song, Jeonghyeon.

In: Physical Review D, Vol. 67, No. 1, 015001, 01.12.2003.

Research output: Contribution to journalArticle

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