Using the form factors from light-cone sum rules, we study the branching ratios and forward-backward asymmetries （FBAs） of the exclusive decays Bu^＋→π^＋e^＋e^- and Bu^＋ →ρ^＋e^＋e^- （e= e,μ） in the standar...Using the form factors from light-cone sum rules, we study the branching ratios and forward-backward asymmetries （FBAs） of the exclusive decays Bu^＋→π^＋e^＋e^- and Bu^＋ →ρ^＋e^＋e^- （e= e,μ） in the standard model （SM） and the top quark two-Higgs-doublet model （T2HDM）. From the numerical results, we find that the new physics contributions cannot provide very large enhancement to the branching ratios and the theoretical predictions are in good agreement with the SM ones. The T2HDM effects on FBAs of these decays are small. Precision measurements of the dilepton invariant mass distributions, especially in the lower dilepton mass region, and the FBAs in the decays Bu^＋ → π^＋ （ρ^＋ ）e^＋ e^- will greatly help in discriminating among the SM and the new physics models.展开更多
Using the topcolor-assisted technicolor models,we give the anomalous Wtb couplings arising from the exchange of the new gauge bosons(ETC gauge boson,colorons and Z')and calculate their contributions to the b→sγb...Using the topcolor-assisted technicolor models,we give the anomalous Wtb couplings arising from the exchange of the new gauge bosons(ETC gauge boson,colorons and Z')and calculate their contributions to the b→sγbranching ratio.We find that the contributions mainly come from colorons and the recent measured value of the b→sγbranching ratio gives a strong constraint on the masses of colorons.展开更多
We calculate the contributions to the rare B-decays,B→Xs,d vv and Bs,d→l+l-from the unit-charged technipions.Within the considered parameter space we find that:(a)the enhancements to the branching ratios in question...We calculate the contributions to the rare B-decays,B→Xs,d vv and Bs,d→l+l-from the unit-charged technipions.Within the considered parameter space we find that:(a)the enhancements to the branching ratios in question can be as large as three orders of magnitude;(b)the ALEPH data of B→Xsvv lead to strong mass bounds on mpl and mp8:mp8≥620,475 GeV for FQ=40 GeV and mpl=100,400 GeV,respectively;(c)the CDF data of Bs→μμlead to a relatively weak limit:mp8≥320 GeV for FQ=40 GeV and mpl=200 GeV.展开更多
The large electron positron collider value of branching ratio Rb is larger than the standard model predicted value RSMb,this deviationδRb is treated as an allowed range for the correction to the single top quark prod...The large electron positron collider value of branching ratio Rb is larger than the standard model predicted value RSMb,this deviationδRb is treated as an allowed range for the correction to the single top quark production cross sectionσ(tb)arising from the extended technicolor dynamics.It is found that the relative correctionδσ(tb)/σ0(tb)is quite large for a certain range of the free parameters in the model,and may be detected in the future proton-antiproton collision experiments.展开更多
基金National Natural Science Foundation of China under Grant No.10575052the Specialized Research Fund for the Doctoral Program of Higher Education (SRFDP) under Grant No.20050319008the Special Study Foundation of Nanyang Normal University under Grant No.nynu200750
文摘Using the form factors from light-cone sum rules, we study the branching ratios and forward-backward asymmetries （FBAs） of the exclusive decays Bu^＋→π^＋e^＋e^- and Bu^＋ →ρ^＋e^＋e^- （e= e,μ） in the standard model （SM） and the top quark two-Higgs-doublet model （T2HDM）. From the numerical results, we find that the new physics contributions cannot provide very large enhancement to the branching ratios and the theoretical predictions are in good agreement with the SM ones. The T2HDM effects on FBAs of these decays are small. Precision measurements of the dilepton invariant mass distributions, especially in the lower dilepton mass region, and the FBAs in the decays Bu^＋ → π^＋ （ρ^＋ ）e^＋ e^- will greatly help in discriminating among the SM and the new physics models.
基金Supported by the National Natural Science Foundation of China under Grant No.19905004the Excellent Youth Foundation of Henan Scientific Commit tee and Foundation of Henan Educational Commit tee.
文摘Using the topcolor-assisted technicolor models,we give the anomalous Wtb couplings arising from the exchange of the new gauge bosons(ETC gauge boson,colorons and Z')and calculate their contributions to the b→sγbranching ratio.We find that the contributions mainly come from colorons and the recent measured value of the b→sγbranching ratio gives a strong constraint on the masses of colorons.
基金Supported by the National Natural Science Foundation of China under Grant No.19575015the Sino-British Friendship Scholarship Scheme。
文摘We calculate the contributions to the rare B-decays,B→Xs,d vv and Bs,d→l+l-from the unit-charged technipions.Within the considered parameter space we find that:(a)the enhancements to the branching ratios in question can be as large as three orders of magnitude;(b)the ALEPH data of B→Xsvv lead to strong mass bounds on mpl and mp8:mp8≥620,475 GeV for FQ=40 GeV and mpl=100,400 GeV,respectively;(c)the CDF data of Bs→μμlead to a relatively weak limit:mp8≥320 GeV for FQ=40 GeV and mpl=200 GeV.
基金Supported by the National Natural Science Foundation of China under Grant No.19775012the Natural Foundation of He7nan Scientific Committee。
文摘The large electron positron collider value of branching ratio Rb is larger than the standard model predicted value RSMb,this deviationδRb is treated as an allowed range for the correction to the single top quark production cross sectionσ(tb)arising from the extended technicolor dynamics.It is found that the relative correctionδσ(tb)/σ0(tb)is quite large for a certain range of the free parameters in the model,and may be detected in the future proton-antiproton collision experiments.
