eμ Production in R-Parity Violating Supersymmetric Model at Hadron Colliders

We investigate the lepton flavor violating productions pp/pp→eμ ＋ X in the framework of the R-parity violating （RPV） supersymmetric model at the Tevatron and the CERN large hadron collider （LHC）. We present the total cross sections including the next-to-leading order （NLO） QCD corrections and the contribution from gluon-gluon fusion subprocess. Our numerical results show that the one-loop QCD corrections significantly increase the tree-level cross sections, and the variation of K factor is in the range between 1.28 （1.32） and 1.79 （1.58） at the Tevatron （LHC）. We find that the QCD correction from the one-loop gluon-gluon fusion subprocess is remarkable at the LHC and should be taken into account.     

Baryon ＋ Baryon→（ΩΩ）J^π=0＋ ＋ X Cross Section Calculation

The cross sections of Ω Ξ→（ΩΩ）J^π=0 K(K^*) and Ω Ω→（ΩΩ）J^π=0 η‘(φ) are studied by using an effective Hamiltonian method.For the two pseudo-scalar meson production processes,the cross sections are still in the order of several μbs,but for the two vector meson production processes,the cross sections are about 10 times larger than those in pseudo-scalar meson production case when the coupling constants of vector meson fields are fixed according to gNNρ and fNNρ in NN scattering and the SU(3) relation.     

Lepton Polarization Asymmetry in B → e^＋e^- Decay beyond the Standard Model

The lepton polarization asymmetry in the B → e^＋e^- decay, when one of the leptons is polarized, is investigated by using the most general form of the effective Hamiltonian. We find allowed regions for the new scalar Wilson coefficients, assuming that the experimental branching ratio is measured within 10% percent uncertainty. Then using these restrictions to the new coefficients the sensitivity of the lepton polarization asymmetry to them is studied. Moreover, it is observed that there are regions of terms describing the scalar interactions, where lepton polarization asymmetry differs from zero, which can serve as a good test for searching new physics beyond the standard model.     

Searching for new physics in D^0→μ^＋ μ^-,e^＋e^-,μ^±e at BES and/or the super charm-tau factory

In contrast with B0-ˉB0, Bs-ˉBs mixing where the standard model（SM） contributions overwhelm that of the new physics beyond standard model（BSM）, a measured relatively large D0-ˉD0mixing where the SM contribution is negligible, definitely implies the existence of the new physics BSM. It is natural to consider that the rare decays of D meson might be more sensitive to new physics, and the decay mode D0→μ＋μ-could be an ideal area to search for new physics because it is a flavor changing process. In this work we look for a trace of the new physics BSM in the leptonic decays of D0. Concretely we discuss the contributions of unparticle or an extra gauge boson Z while imposing the constraints set by fitting the D0-ˉD0mixing data. We find that the long-distance SM effects for D0→lˉl still exceed those contributions of the BSM under consideration, but for a double-flavor changing process such as D0→μ±e, the new physics contribution would be significant.     

t →cγ and t →cg in Local Gauged Baryon and Lepton Numbers

In this paper, we calculate the top quark rare decays t →cγ and v in an extension of the standard model, where baryon number and lepton number are local gauge symmetries. Adopting reasonable assumptions on the parameter space, we find that the branching ratios of t →cγ and t →cg can reach 10^-6 and 10^-5 respectively, which can be detected in near future.     

The Effects from the Complex Parameters on t→ch^0 Within the Minimal Supersymmetric Standard Model

We investigate the effects from complex parameters on the branching ratio (BR) of the flavor changing rare decay t→ch^0 contributed by the electroweak interactions in the framework of the minimal supersymmetric standard model with complex parameters. We study the dependence of the BR on the possible relevant additional parameter swhich could be the originalsources inducing CP-violation, i.e., the complex phase angles φμ and φAb in squark and chargino sectors and δ13 appearing in Cabibbo-Kobayashi-Maskawa matrix. We find that these parameters influence the BR obviously and the effects induced by φμ and φAb are much larger than by δ13. With the different chosen values of the complex parameters, the BR is in the range between 10^-10 and 10^-8, depending mainly on the phase angles of the higgsino mass parameter μ and the trilinear coupling Ab.     

B→ X8γ, X8l＋l- Decays and Constraints on Mass Insertion Parameters in MSSM

In this paper, we study the upper bounds on the mass insertion parameters （δAB^q）ij in the minimal super symmetric standard model. We found that the information from the measured branching ratio of B→ X8γ, X8l＋l- decay can help us to improve the upper bounds on the mass insertions parameters （δAB^u,d）3j,i3 Some regions allowed by the data of Br（B→ X8γ） are excluded by the requirement of an SM-like C7γ （rnb） imposedby the data of Br（B→ X8γ, X8l＋l- ）.