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Direct CP violation in semi-inclusive flavor-changing quark decays in the MSSM without R-parity

Semi-inclusive decays, hlx, are studied in the framework of the minimal supersymmetric standard model without R-parity, where qh (ql) are the second or third (first or second) generation quarks with the same charge and xi is a vector meson formed by q_j qb_j. The study is focused on the contributions of sfermions with m_{sf} < m_{rm top}. In this mass region, CP asymmetries in top decays can be induced by taking into account the decay-widths of the exchanged-bosons, while in light-quark decays it can be generated due to the long-distance effects. The contributions of sfermions also alter the branching-ratios destructively… Selengkapnya

Branching ratio and CP violation in semi-inclusive flavor-changing top decays

Semi-inclusive top decays, t rightarrow q_i v, are examined in the framework of the standard model, with q_i = u ; {rm or} ; c, v : vector meson formed by q_j qb_j (q_j = d, s, b). By using a simple model of hadronization, that is < 0 l~~ qb_j gamma^mu q_j r~~ v > = mv fv evj^mu, the total branching ratio is expected to be br(tivj) < ( {l~~ vij^ast vtj r~~}/{l~~ vtb r~~})^2 times O({10}^{-3}) depends on the size of the coupling constant fv. On the other hand, the CP asymmetry should be induced only by… Selengkapnya

Determination of the CKM matrix by semileptonic rare B-decays

The possibility to test the unitarity triangle of CKM matrix is examined by using the semileptonic rare B decays, B rightarrow X_q , l^+ , l^- with q = d, s and ls are leptons. The discussion is emphasized on the CP asymmetry in the framework of standard and beyond the standard models. For the beyond standard model, a minimal extension of the standard model containing an additional isosinglet charge (-1/3) charge quark, which leads to a deviation from CKM unitarity, is considered. As the results, in the standard model the CP asymmetry is visible only for B rightarrow X_d… Selengkapnya

Determination of CKM unitarity triangle by B -> X_d l^+ l^- decay

I examine a possibility to extract the angle gamma in the Cabibbo-Kobayashi-Maskawa unitarity triangle through the inclusive decay B rightarrow X_d , l^+ , l^- . An independent information for the angle is expected from the non-trivial contribution induced in u bar{u} and c bar{c} loops. The contributions induce CP asymmetry which has high sensitivity to the angle gamma in the whole region of dilepton invariant mass. Particularly, in the region of low dilepton invariant mass, the sensitivity is also recognized in the branching-ratio with any dilepton final states and the lepton polarization asymmetry with dimuon final state. In the… Selengkapnya

Semileptonic B decay as a test of CKM unitarity

I point out that B rightarrow X_q , l^+ , l^- decays (q = s, d) are sensitive probes of possible violation of CKM unitarity. I compute the decay rates and asymmetries in a minimal extension of the Standard Model containing an additional isosinglet charge (-1/3) quark, which leads to a deviation from CKM unitarity. It is shown that even for small mixing ratios left~~ {z_{qb}}/{(V_{tq}^ast V_{tb})} right~~ sim O({10}^{-2}), the contribution of the tree-level Z-FCNC appearing in the model should change the rates and asymmetries significantly. Especially the CP asymmetry, {cal A}_{rm CP} (B rightarrow X_s , l^+ ,… Selengkapnya

Asymmetries in B -> X_d l^+ l^- decay

We attempt to extract the angle $gamma$ of the Cabibbo-Kobayashi-Maskawa matrix by the inclusive $B rightarrow X_d , l^+ , l^- $ decay. The possibility is coming out because the channel includes non-trivial terms with the factor $V_{ud}^ast , V_{ub}$ induced in the continuum and resonances parts of $u bar{u}$ loop. Selengkapnya

Rare decays in the b-d system

We examine several asymmetries which are considerable in the rare b -> d decays. The paper is focused on the semi-leptonic B -> X_d l^+ l^- decay. It is shown that $CP-$violation factor in the process gives non-trivial behaviour in the CP and lepton polarization asymmetries, but does not in the decay distribution and forward-backward asymmetry. Selengkapnya

Power Corrections in the Decay Rate and Distributions in B -> X_s l^+ l^- in the Standard Model

We investigate the leading power corrections to the decay rates and distributions in the decay bxsll in the standard model (SM) using heavy quark expansion (HQE) in (1/m_b) and a phenomenological model implementing the Fermi motion effects of the b quark bound in the B hadron. In the HQE method, we find that including the leading power corrections the decay width Gamma(mbox{bxslll}) decreases by about 4 persen and the branching ratio {cal B}(bxslll) by about 1.5 persen from their (respective) parton model values. The dilepton invariant mass spectrum is found to be stable against power corrections over a good part… Selengkapnya