Precision Flavour Physics with B→KννˉB\to K\nu\bar\nu and B→Kl+l−B\to Kl^+l^-

We show that a combined analysis of $B\to K\nu\bar\nu$ and $B\to Kl^+l^-$ allows for new physics tests practically free of form factor uncertainties. Residual theory errors are at the level of several percent. Our study underlines the excellent motivation for measuring these modes at a Super Flavour Factory.Comment: 26 pages, 2 figure

Prospects for detecting an ηc′\eta_c' in two photon processes

We argue that an experimental search for an $\eta_c'$, the first radial excitation of the $\eta_c(2980)$, may be carried out using the two photon process e^+e^- \to e^+e^- \gamma \gamma \ra e^+e^-\eta_c'. We estimate the partial width $\Gamma_{\gamma \gamma}(\eta_c')$ and the branching fraction $B(\eta_c' \to h)$, where $h$ is an exclusive hadronic channel, and find that for $h = K^o_s K^\pm \pi^\mp$ it may be possible to observe this state in two photon collisions at CLEO-II.Comment: 9 pages, LATEX forma

Note on the pseudo-Nambu-Goldstone Boson of Meta-stable SUSY Violation

Many models of meta-stable supersymmetry (SUSY) breaking lead to a very light scalar pseudo-Nambu Goldstone boson (PNGB), P, associated with spontaneous breakdown of a baryon number like symmetry in the hidden sector. Current particle physics data provide no useful constraints on the existence of P. For example, the predicted decay rates for both K --> pi + P, b--> s + P and Upsilon --> photon + P are many orders of magnitude below the present experimental bounds. We also consider astrophysical implications of the PNGB and find a significant constraint from its effect on the evolution of red giants. This constraint either rules out models with a hidden sector gauge group larger than SU(4), or requires a new intermediate scale, of order at most 10^{10} GeV, at which the hidden sector baryon number is explicitly broken.Comment: 17 pages, 3 figures. Version 2: minor typographical errors fixed. Version 3: a more reliable estimate for the decay rate of K-->pi+PNGB is provided, and the predicted rate for b-->s+PNGB is now include

Is there New Physics in B Decays ?

Rare decays of the $B$ meson are sensitive to new physics effects. Several experimental results on these decays have been difficult to understand within the standard model (SM) though more precise measurements and a better understanding of SM theory predictions are needed before any firm conclusions can be drawn. In this talk we try to understand the present data assuming the presence of new physics. We find that the data points to new physics of an extended Higgs sector and we present a two higgs doublet model with a 2-3 flavor symmetry in the down type quark sector that can explain the deviations from standard model reported in several rare B decays.Comment: 8 pages, Talk presented at Theory Canada II, Perimeter Institute, Waterloo, Canada. New references added and update

R-parity-violating SUSY and CP violation in B --> phi K_s

Recent measurements of CP asymmetry in B --> phi K_S appear to be inconsistent with Standard Model expectations. We explore the effect of R-parity-violating SUSY to understand the data.Comment: Equations corrected. Conclusions unchanged. Latex, 6 pages, one fi

B-> K photon photon via intermediate eta'

We examine our previous conjecture that the eta' intermediate resonance has the dominant role in the long distance contributions to B decay into two photons and a strange final state hadron. We calculate the branching ratio of the exclusive B-> K eta'-> K photon photon decay using the nonspectator mechanism for eta' production in charmless hadronic B decays. It is shown that the obtained branching ratio B^eta'(B-> K\gamma\gamma)~ 8.7 X 10^{-7} is more than twice as large as the eta_c contribution to this decay mode.Comment: 6 pages, latex, no figure

A study of semi-inclusive charmless B→πXB \to \pi X decays

We study semi-inclusive charmless decays $B \to \pi X$ in detail, such as $\bar B^0 \to \pi^{\pm (0)} X$, $B^0 \to \pi^{\pm (0)} X$, $B^{\pm} \to \pi^{\pm (0)} X$, where $X$ does not contain a charm (anti)quark. We find that the process $\bar B^0 \to \pi^- X$ ($B^0 \to \pi^+ X$) can be particularly useful for determination of the CKM matrix element $|V_{ub}|$. We calculate and present the branching ratio (BR) of $\bar B^0 \to \pi^- X$ as a function of $|V_{ub}|$, with an estimate of possible uncertainties. It is expected that the BR is an order of $10^{-4}$. Our estimation indicates that one can phenomenologically determine $|V_{ub}|$ with reasonable accuracy by measuring the BR of $\bar B^0 \to \pi^- X$ ($B^0 \to \pi^+ X$).Comment: 18 pages, 7 figures; Revtex; version accepted for publication in Eur. Phys. J.

Final-State Phases in Doubly-Cabibbo-Suppressed Charmed Meson Nonleptonic Decays

Cabibbo-favored nonleptonic charmed particle decays exhibit large final-state phase differences in $\bar K \pi$ and $\bar K^* \pi$ but not $\bar K \rho$ channels. It is of interest to know the corresponding pattern of final-state phases in doubly-Cabibbo-suppressed decays, governed by the $c \to d u \bar s$ subprocess. An experimental program is outlined for determining such phases via measurements of rates for $D \to K^* \pi$ and $K (\rho, \omega,\phi)$ channels, and determination of interference between bands in Dalitz plots. Such a program is feasible at planned high-intensity sources of charmed particles.Comment: 12 pages, LaTeX, 2 figures, to be submitted to Phys. Rev. D. Revised versio

Constraints on charged Higgs bosons from D(s)+- -> mu+- nu and D(s)+- -> tau+- nu

The decays D(s)+- -> mu+- nu and D(s)+- -> tau+- nu have traditionally been used to measure the D(s)+- meson decay constant f_D(s). Recent measurements at CLEO-c and the B factories suggest a branching ratio for both decays somewhat higher than the Standard Model prediction using f_D(s) from unquenched lattice calculations. The charged Higgs boson (H+-) in the Two Higgs Doublet Model (Type II) would also mediate these decays, but any sizeable contribution from H+- can only suppress the branching ratios and consequently is now slightly disfavoured. It is shown that constraints on the parameters tan(beta) and m_H+- from such decays can be competitive with and complementary to analogous constraints derived from the leptonic meson decays B+- -> tau+- nu_tau and K+- -> mu+- nu_mu, especially if lattice calculations eventually prefer f_D(s) < 250 MeV.Comment: 18 pages, 4 figure

Semi-inclusive B Decays and Direct CP Violation in QCD Factorization

We have systematically investigated the semi-inclusive B decays B->MX, which are manifestations of the quark decay b->Mq, within the framework of QCD-improved factorization. These decays are theoretically clean and have distinctive experimental signatures. We focus on a class of these that do not require any form factor information and therefore may be especially suitable for extracting information on the angles $\alpha$ and $\gamma$ of the unitarity triangle. The nonfactorizable effects, such as vertex-type and penguin-type corrections to the two-body b decay and hard spectator corrections to the 3-body decay are calculable in the heavy quark limit. QCD factorization is applicable when the emitted meson is a light meson or a charmonium. We discuss the issue of the CPT constraint on partial rate asymmetries. The strong phase coming from final-state rescattering due to hard gluon exchange between the final states can induce large rate asymmetries for tree-dominated color-suppressed modes $(\pi^0,\rho^0,\omega)X_{\bar s}$. The nonfactorizable hard spectator interactions in the 3-body decay, though phase-space suppressed, are extremely important for the tree-dominated modes $(\pi^0,\rho^0,\omega)X_{\bar s}, \phi X$, $J X_s,J X$ and the penguin-dominated mode $\omega X_{s\bar s}$. In fact, they are dominated by the hard spectator corrections. Our result for ${\cal B} (B\to J/\psi X_s)$ is in agreement with experiment. The semi-inclusive decay modes: $B^0_s\to (\pi^0,\rho^0,\omega)X_{\bar s}$, $\rho^0X_{s\bar s}$, $B^0\to(K^-X,K^{*-}X)$ and $B^-\to (K^0X_s,K^{*0}X_s)$ are the most promising ones in searching for direct CP violation. In fact, they have branching ratios of order $10^{-6}-10^{-4}$ and CP rate asymmetries of order $(10-40)$.Comment: 28 page