81 research outputs found

### Determination of the CP violating weak phase $\gamma$ from the Decays $B \to D \pi$

We propose a new method to extract the CP violating weak phase $\gamma$ (the
phase of $V_{ub}^*$) in the CKM paradigm of the Standard Model, using $B^-
\rightarrow D^0 \pi^- \rightarrow f \pi^-$ and $B^- \rightarrow \bar D^0 \pi^-
\rightarrow f \pi^-$ decays, where $f$ are final states such as $K^+ \pi^-$,
$K^+ \rho^-$, $K \pi\pi$, {\it etc.} We also study the experimental feasibility
of our new method. With possibility of new phases in the CKM matrix, we
re-examine some of the previously proposed methods to determine $\gamma$, and
find that it would be in principle possible to identify $\gamma$ and a new
phase angle $\theta$ separately.Comment: 12 pages, 1 figure, LaTex; the version to be published in European
Physical Journal

### Charmless hadronic B decays and the recent CLEO data

In the light of recent experimental data from the CLEO Collaboration we
study, the decays of B mesons to a pair of pseudoscalar (P) mesons, and a
vector (V) meson and a pseudoscalar meson, in the framework of factorization.
In order to obtain the best fit for the recent CLEO data, we critically examine
the values of several input parameters to which the predictions are sensitive.
These input parameters are the form factors, the strange quark mass, $\xi
\equiv 1/ N_c$ (N_c is the effective number of color), the CKM matrix elements
and in particular, the weak phase $\gamma$. It is possible to give a
satisfactory account of the recent experimental results in $B \to PP$ and VP
decays, with constrained values of a \emph{single} $\xi$. We identify the decay
modes in which CP asymmetries are expected to be large.Comment: 24 pages, 11 figures, LaTex; Version to appear in Phys. Rev.

### Constraints on a New Light Spin-One Particle from Rare b -> s Transitions

The anomalously large like-sign dimuon charge asymmetry in semileptonic
b-hadron decays recently measured by the D0 Collaboration may be hinting at the
presence of CP-violating new physics in the mixing of B_s mesons. It has been
suggested that the effect of a nonstandard spin-1 particle lighter than the b
quark with flavor-changing couplings to b and s quarks can reproduce the D0
result within its one-sigma range. Here we explore the possibility that the new
particle also couples to charged leptons l=e,mu and thus contributes to rare b
-> s processes involving the leptons. We consider in particular constraints on
its couplings from existing experimental data on the inclusive B -> X_s l^+ l^-
and exclusive B -> K^{(*)} l^+ l^- decays, as well as the anomalous magnetic
moments of the leptons. We find that there is parameter space of the particle
that is allowed by the current data. Future measurements of these B transitions
and rare decays of the B_s meson, such as B_s -> (phi,eta,eta') l^+ l^- and B_s
-> l^+ l^-, at LHCb and next-generation B factories can probe its presence or
couplings more stringently.Comment: 19 pages, 5 figure

### An extension of tribimaximal lepton mixing

Harrison, Perkins and Scott have proposed simple charged lepton and neutrino
mass matrices that lead to the tribimaximal mixing $U_{\rm TBM}$. We consider
in this work an extension of the mass matrices so that the leptonic mixing
matrix becomes $U_{\rm PMNS}=V_L^{\ell\dagger}U_{\rm TBM}W$, where $V_L^\ell$
is a unitary matrix needed to diagonalize the charged lepton mass matrix and
$W$ measures the deviation of the neutrino mixing matrix from the bimaximal
form. Hence, corrections to $U_{\rm TBM}$ arise from both charged lepton and
neutrino sectors. Following our previous work to assume a Qin-Ma-like
parametrization $V_{\rm QM}$ for the charged lepton mixing matrix $V_L^\ell$ in
which the {\it CP}-odd phase is approximately maximal, we study the
phenomenological implications in two different scenarios: $V_L^\ell=V_{\rm
QM}^\dagger$ and $V_L^\ell=V_{\rm QM}$. We find that the latter is more
preferable, though both scenarios are consistent with the data within $3\sigma$
ranges. The predicted reactor neutrino mixing angle $\theta_{13}$ in both
scenarios is consistent with the recent T2K and MINOS data. The leptonic {\it
CP} violation characterized by the Jarlskog invariant $J_{\rm CP}$ is generally
of order $10^{-2}$.Comment: 20 pages and 8 figures, Accepted in Phys.Review

### Charmless Non-Leptonic B Decays and R-parity Violating Supersymmetry

We examine the charmless hadronic B decay modes in the context of R-parity
violating (\rpv) supersymmetry. We try to explain the large branching ratio
(compared to the Standard Model (SM) prediction) of the decay $B^{\pm}\to \eta'
K^{\pm}$. There exist data for other observed $\eta^{(\prime)}$ modes and among
these modes, the decay $B^{0}\to \eta K^{*0}$ is also found to be large
compared to the SM prediction. We investigate all these modes and find that
only two pairs of \rpv coupling can satisfy the requirements without
affecting the other B\ra PP and B\ra VP decay modes barring the decay
B\ra\phi K. From this analysis, we determine the preferred values of the
\rpv couplings and the effective number of color $N_c$. We also calculate the
CP asymmetry for the observed decay modes affected by these new couplings.Comment: 14 pages, 7 figures; revtex; version published in Phys. Lett.

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