Extracting short distance information from b-->s[script-l]+[script-l]- effectively

We point out that in inclusive B-->Xs[script-l]+[script-l]- decay an angular decomposition provides a third (q2 dependent) observable sensitive to a different combination of Wilson coefficients than the rate and the forward-backward asymmetry. Since a precise measurement of q2 dependence requires large data sets, it is important to consider the data integrated over regions of q2. We develop a strategy to extract all measurable Wilson coefficients in B-->Xs[script-l]+[script-l]- from a few simple integrated rates in the low q2 region. A similar decomposition in B-->K*[script-l]+[script-l]-, together with the B-->K*gamma rate, also provides a determination of the Wilson coefficients, without reliance on form factor models and without having to measure the zero of the forward-backward asymmetry

Universality and m_X cut effects in B -> Xs l+ l-

The most precise comparison between theory and experiment for the B -> Xs l+ l- rate is in the low q^2 region, but the hadronic uncertainties associated with an experimentally required cut on m_X potentially spoil the search for new physics in these decays. We show that a 10-30% reduction of d\Gamma(B -> Xs l+ l-) / dq^2 due to the m_X cut can be accurately computed using the B -> X_s gamma shape function. The effect is universal for all short distance contributions in the limit m_X^2 << m_B^2, and this universality is spoiled neither by realistic values of the m_X cut nor by alpha_s corrections. Both the differential decay rate and forward-backward asymmetry with an m_X cut are computed.Comment: 5 pages, journal versio

Fermionic corrections to the interference of the electro- and chromomagnetic dipole operators in anti-B --> X(s) gamma at O(alpha(s)**2)

We calculate the virtual and bremsstrahlung fermionic corrections due to the interference of the electro- and chromomagnetic dipole operators in the inclusive \bar{B}\to X_s\gamma decay at O(\alpha_s^2) and present analytical results for both the total decay rate and the photon energy spectrum.Comment: 13 pages, uses axodraw.sty; minor changes, matches published versio

Transverse tau polarization in inclusive Bˉ→τνˉX\bar B\to \tau \bar\nu X decays

We calculate, in the framework of multi Higgs doublet models, the $CP$ violating transverse tau polarization, $P_\perp$, in inclusive semileptonic $B$ meson decays. We find that $P_\perp$ diverges at ${\cal O}(1/m_b^2)$ of the heavy quark expansion. We discuss the physical reasons for this divergence and show how to regularize it. We find large $1/m_b^2$ corrections that can suppress the $CP$ asymmetry by as much as 30\%. The maximal allowed asymmetry is $a_{CP}\sim0.34$. We discuss how the allowed range is expected to change in the future.Comment: 12 pages RevTeX + 1 figure included, WIS-94/39/Sep-PH, CALT-68-1952. (No changes at all; postscript figure submitted separately as requested.

CP violation and limits on New Physics including recent BsB_s measurements

We analyse present constraints on the SM parameter space and derive, in a model independent way, various bounds on New Physics contributions to $B_d^0$--$\bar B_d^0$ and $B_s^0$--$\bar B_s^0$ mixings. Our analyses include information on a large set of asymmetries, leading to the measurement of the CKM phases $\gamma$ and $\bar\beta$, as well as recent data from D0 and CDF related to the $B_s^0$--$\bar B_s^0$ system such as the measurement of $\Delta M_{B_s}$, $A_{SL}$ and $\Delta\Gamma_{s}^{CP}$. We examine in detail several observables such as the asymmetries $A_{sl}^d$, $A_{SL}$, the width differences $\Delta\Gamma_{d}$ and $\Delta\Gamma_{s}^{CP}$ and discuss the r\^ole they play in establishing the limits on New Physics. The present data clearly favour the SM, with the New Physics favoured region placed around the SM solution. A New Physics solution significantly different from the SM is still allowed, albeit quite disfavoured (2.6% probability). We analyse the presently available indirect knowledge on the phase $\bar\chi$ entering in $B_s^0$--$\bar B_s^0$ mixing and study the impact of a future measurement of $\bar\chi$ to be achieved at LHC, through the measurement of the time-dependent CP asymmetry in $B_s\to J/\Psi \Phi$ decays.Comment: 29 pages, 31 figures; updated analyses and reference

Logarithmically Enhanced Corrections to the Decay Rate and Forward Backward Asymmetry in anti-B --> X(s) l+ l-

We study logarithmically enhanced electromagnetic corrections to the decay rate in the high dilepton invariant mass region as well as corrections to the forward backward asymmetry (FBA) of the inclusive rare decay $\bar{B} \to X_s \ell^+ \ell^-$. As expected, the relative effect of these corrections in the high dilepton mass region is around -8% for the muonic final state and therefore much larger than in the low dilepton mass region. We also present a complete phenomenological analysis, to improved NNLO accuracy, of the dilepton mass spectrum and the FBA integrated in the low dilepton mass region, including a new approach to the zero of the FBA. The latter represents one of the most precise predictions in flavour physics with a theoretical uncertainty of order 5%. We find (q_0^2)_{\mu\mu} = (3.50 \pm 0.12) \gev^2. For the high dilepton invariant mass region, we have ${\cal B}(\bar B\to X_s\mu\mu)_{\rm high} = (2.40^{+0.69}_{-0.62}) \times 10^{-7}$. The dominant uncertainty is due to the $1/m_b$ corrections and can be significantly reduced in the future. For the low dilepton invariant mass region, we confirm previous results up to small corrections.Comment: 26 pages, 3 figures, minor changes, published versio

Nonperturbative Effects in Bˉ→Xsl+l−\bar B\to X_s l^+l^- for Large Dilepton Invariant Mass

We reconsider the calculation of ${\cal O}(\Lambda^2_{QCD}/m^2_b)$ nonperturbative corrections to $\bar B\to X_sl^+l^-$ decay. Our analysis confirms the results of Ali et al. for the dilepton invariant mass spectrum, which were in disagreement with an earlier publication, and for the lepton forward-backward asymmetry. We also give expressions for the ${\cal O}(\Lambda^2_{QCD}/m^2_b)$ corrections to the left-right asymmetry. In addition we discuss the breakdown of the heavy quark expansion near the point of maximal dilepton invariant mass $q^2$ and consider a model independent approach to this region using heavy hadron chiral perturbation theory. The modes $\bar B\to\bar Kl^+l^-$ and $\bar B\to\bar K\pi l^+l^-$, which determine the endpoint region of the inclusive decay, are analyzed within this framework. An interpolation is suggested between the region of moderately high $q^2$, where the heavy quark expansion is still valid, and the vicinity of the endpoint described by chiral perturbation theory. We also comment on further nonperturbative effects in $\bar B\to X_sl^+l^-$.Comment: 18 pages, LaTeX, 1 figur

EDMs vs. CPV in B_{s,d} mixing in two Higgs doublet models with MFV

We analyze the correlations between electric dipole moments (EDMs) of the neutron and heavy atoms and CP violation in B_{s,d} mixing in two Higgs doublet models respecting the Minimal Flavour Violation hypothesis, with flavour-blind CP-violating (CPV) phases. In particular, we consider the case of flavour-blind CPV phases from i) the Yukawa interactions and ii) the Higgs potential. We show that in both cases the upper bounds on the above EDMs do not forbid sizable non-standard CPV effects in B_s mixing. However, if a large CPV phase in B_s mixing will be confirmed, this will imply EDMs very close to their present experimental bounds, within the reach of the next generation of experiments, as well as BR(B_{s,d}-> mu^+ mu^-) typically largely enhanced over its SM expectation. The two flavour-blind CPV mechanisms can be distinguished through the correlation between S_psi K_S and S_psi phi that is strikingly different if only one of them is relevant. Which of these two CPV mechanisms dominates depends on the precise values of S_psi phi and S_psi K_S, as well as on the CKM phase (as determined by tree-level processes). Current data seems to show a mild preference for a hybrid scenario where both these mechanisms are at work.Comment: 9 pages, 8 figures. V2: minor modifications, few typos corrected, few refs adde

The Decay D0→Kˉ∗0π−e+νeD^0\to \bar K^{*0} \pi^- e^+ \nu_e in the Context of Chiral Perturbation Theory

We study the decay $D^0\rightarrow \bar K^{*0} \pi^- e^+ \nu_e$, using $SU(2)_L \otimes SU(2)_R$ chiral perturbation theory for heavy charmed mesons and vector mesons, in the kinematic regime where $p_M \cdot p_\pi/m_M$ (here $M = D^0$ or $\bar K^{*0}$) is much smaller than the chiral symmetry breaking scale, $\Lambda_{\chi SB}$ ( $\Lambda_{\chi SB} \sim$ 1 GeV). We present the leading diagrams and amplitude, and calculate the rate, in the region where, to leading order in our calculations, the $\bar K^{*0}$ is at zero recoil in the $D^0$ rest frame. The rate thus calculated is given in terms of a known form factor and depends on the $DD^* \pi$ coupling constant $g_D$ of the heavy (charmed) meson chiral perturbation theory Lagrangian. A measurement of the above decay, in the aforementioned kinematic regime, can result in the extraction of an experimental value for $g_D$, accurate at the level of our approximations, and give us a measure of the validity of approaches based on chiral perturbation theory in studying similar processes.Comment: 17 pages, Latex, 2 embedded postscript figure