相关论文: Upper Bounds on Rare K and B Decays from MFV
We make the simple observation that there exists a universal unitarity triangle for all models, like the SM, the Two Higgs Doublet Models I and II and the MSSM with minimal flavour violation, that do not have any new operators beyond those…
The search for rare B decays and direct CP violation at BABAR is described. The following measurements (based on integrated luminosities ranging from 56.4 to 81.9fb-1) are summarized: the inclusive branching fractions and direct CP…
In this paper, we study the upper bounds on the mass insertion parameters $(\delta^{q}_{AB})_{ij}$ in the minimal supersymmetric standard model (MSSM). We found that the information from the measured branching ratio of $B \to X_s l^+ l^-$…
The rare decays {$B^- \to \tau \bar\nu$}, \mbox{$B \to \tau^+ \tau^-$}, {$b \to X \nu \bar\nu$} and \mbox{$b \to X \tau^+ \tau^-$} all contain third generation leptons in the final state, and hence are sensitive to new physics that couples…
A search for the decays Bs-->mumu and Bd-->mumu is performed with about 37 pb^{-1} of pp collisions at sqrt{s} = 7 TeV collected by the LHCb experiment at the Large Hadron Collider at CERN. The observed numbers of events are consistent with…
We analyse the B -> pi pi, pi K modes in the light of the most recent B-factory data, and obtain the following new results: (i) the B0 -> pi+ pi-, pi- K+ modes prefer gamma=(74+-6)deg, which - together with |V_ub/V_cb| - allows us to…
Recent disagreement between experimental measurments of CP violating asymmetry in D -> K+ K- and D ->pi+ pi- and theoretical Standard model expectation motivated many studies within the Standard model and beyond. Rare charm decays offer new…
We study lepton flavor number violating rare B decays, $b \to s l_h^{\pm} l_l^{\mp}$, in a seesaw model with low scale singlet Majorana neutrinos motivated by the resonant leptogenesis scenario. The branching ratios of inclusive decays $ b…
We report on a search for the rare decay K_L -> pi^0 nu nubar in the KTeV experiment at Fermilab. We searched for two-photon events whose kinematics were consistent with an isolated pi^0 coming from the decay K_L -> pi^0 nu nubar. One…
We present the results of a search for the flavor changing neutral current decay B_s^0->mu^+mu^- using 6.1 fb^-1 of ppbar collisions at sqrt(s) = 1.96 TeV collected by the D0 experiment at the Fermilab Tevatron Collider. The observed number…
In this letter, we consider the constraints imposed by the recent measurement of B_s - bar B_s mixing on the new physics contribution to the rare decay B_s --> mu+ mu-. New physics in the form vector and axial-vector couplings is already…
Theories of flavor violation beyond the Standard Model typically suppose that the new contributions must be small, for example suppressed by Yukawa couplings, as in Minimal Flavor Violation. We show that this need not be true, presenting a…
We extend our previous analysis of the decays B_{d,s} -> mu^+ mu^- in the Minimal Supersymmetric Standard Model (MSSM) to include gluino and neutralino contributions. We provide analytic formulae, valid at large values of tan(beta), for the…
In this paper, I study the branching ratio of the rare radiative decay $B_s \to \nu \bar{\nu} \gamma$ in the framework of the Fourth-Generation Standard Model and the Two-Higgs-Doublet Model. It is shown that this quantity is a very…
We extend the standard model by adding an extra generation of isosinglet up- and down-type quark pair which engage in weak interactions only via mixing with the three ordinary quark families. It is shown that the generalized $4\times 4$…
Starting from a (new physics independent) tree level determination of rhobar and etabar, we perform the Unitarity Triangle analysis in general extensions of the Standard Model with arbitrary new physics contributions to loop-mediated…
Charged lepton-flavor violating processes are extremely rare in the Standard Model, but they may occur in several beyond-the-Standard Model theories, including Supersymmetry or models with leptoquarks or compositeness. We present a search…
Recently the LHCb collaboration put the upper limit on the $\Xi^{-}_{b} \rightarrow \Xi^{-}\gamma$ decay branching ratio $Br(\Xi^{-}_{b} \rightarrow \Xi^{-}\gamma)< 1.3\times 10^{-4}$. The measured value is below the light-cone sum rule…
Precision tests of the Standard Model and searches for New Physics in the quark flavor sector depend on accurate theoretical calculations of decay rates and spectra for rare, flavor-changing processes. The theoretical status and recent…
We analyze the branching ratio for the FCNC mode $K^+\to\pi^+\nu\bar\nu$\ in the standard model with QCD effects taken into account consistently to next-to-leading order. This involves a two-loop renormalization group analysis for the charm…