630 research outputs found

    Isospin Considerations in Correlations of Pions and BB mesons

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    The correlations between a BB meson and a pion produced nearby in phase space should respect isospin reflection symmetry I3→−I3I_3 \to -I_3. Thus, one generally expects similar π+B0\pi^+ B^0 and π−B+\pi^- B^+ correlations (non-exotic channels), and similar π−B0\pi^- B^0 and π+B+\pi^+ B^+ correlations (exotic channels). Exceptions include (a) fragmentation processes involving exchange of quarks with the producing system, (b) misidentification of charged kaons as charged pions, and (c) effects of decay products of the associated B‟\overline{B}. All of these can affect the apparent signal for correlations of charged BB mesons with charged hadrons. The identification of the flavor of neutral BB mesons through the decay B0→K∗0J/ψB^0 \to K^{*0} J/\psi requires good particle identification in order that the decay K∗0→K+π−K^{*0} \to K^+ \pi^- not be mistaken for K‟∗0→K−π+\overline{K}^{*0} \to K^- \pi^+, in which case the correlations of neutral BB mesons with hadrons can be underestimated.Comment: LaTeX EPSF file; 8 uuencoded figures to be submitted separatel

    SU(3) Decomposition of Two-Body B Decay Amplitudes

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    We present the complete flavor SU(3) decomposition of decay amplitudes for decays of the triplet (B^+_u, B^0_d, B^0_s) of B mesons nonleptonically into two pseudoscalar mesons. This analysis holds for arbitrarily broken SU(3) and can be used to generate amplitude relations when physical arguments permit one to neglect or relate any of the reduced amplitudes.Comment: 31 pages, revtex, no figure

    CP Violation Studies at Tevatron

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    We present an overview of a few recent results related to CP-violation from the Tevatron. First, we discuss a measurement of the dimuon charge asymmetry from D{\O}that extracts the CP-violation parameter of \Bo mixing and decay. This is followed by the CDF measurement of the CP-violating asymmetry in \bdkpi decays. Finally we give the CDF result on the ratio R=BR(B→D0K)BR(B→D0π)R = \frac{BR(B \to D^0 K)}{BR(B \to D^0 \pi)}Comment: 4 pages. Talk given at BEACH 2006, Lancaster, Englan

    Exploring CP Violation with B_d -> D K_s Decays

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    We (re)examine CP violation in the decays B_d -> D K_s, where D represents D^0, D(bar), or one of their excited states. The quantity sin⁥2(2ÎČ+Îł)\sin^2(2\beta + \gamma) can be extracted from the time-dependent rates for Bd(t)−>Dˉ∗∗0KsB_d(t) -> {\bar D}^{**0} K_s and Bd(t)−>D∗∗0KsB_d(t) -> D^{**0} K_s, where the D∗∗0D^{**0} decays to D(∗)+π−D^{(*)+}\pi^-. If one considers a non-CP-eigenstate hadronic final state to which both D(bar) and D^0 can decay (e.g. K+π−K^+\pi^-), then one can obtain two of the angles of the unitarity triangle from measurements of the time-dependent rates for Bd(t)−>(K+π−)DKsB_d(t) -> (K^+\pi^-)_{D K_s} and Bd(t)−>(K−π+)DKsB_d(t) -> (K^-\pi^+)_{D K_s}. There are no penguin contributions to these decays, so all measurements are theoretically clean.Comment: 15 pages, LaTeX, no figure

    B-Decay CP Asymmetries, Discrete Ambiguities and New Physics

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    The first measurements of CP violation in the BB system will likely probe sin⁥2α\sin 2\alpha, sin⁥2ÎČ\sin 2\beta and cos⁥2Îł\cos 2\gamma. Assuming that the CP angles α\alpha, ÎČ\beta and Îł\gamma are the interior angles of the unitarity triangle, these measurements determine the angle set (α,ÎČ,Îł)(\alpha,\beta,\gamma) except for a twofold discrete ambiguity. If one allows for the possibility of new physics, the presence of this discrete ambiguity can make its discovery difficult: if only one of the two candidate solutions is consistent with constraints from other measurements in the BB and KK systems, one is not sure whether new physics is present or not. We review the methods used to resolve the discrete ambiguity and show that, even in the presence of new physics, they can usually be used to uncover this new physics. There are some exceptions, which we describe in detail. We systematically scan the parameter space and present examples of values of (α,ÎČ,Îł)(\alpha,\beta,\gamma) and the new-physics parameters which correspond to all possibilities. Finally, we show that if one relaxes the assumption that the bag parameters \BBd and \BK are positive, one can no longer definitively establish the presence of new physics.Comment: 29 pages, LaTeX, 1 figures, presentation substantially reworked, physics conclusions unchanged. This version will be published in Phys. Rev.

    Extracting Weak Phase Information from B -> V_1 V_2 Decays

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    We describe a new method for extracting weak, CP-violating phase information, with no hadronic uncertainties, from an angular analysis of B -> V_1 V_2 decays, where V_1 and V_2 are vector mesons. The quantity sin⁥2(2ÎČ+Îł)\sin^2 (2\beta + \gamma) can be cleanly obtained from the study of decays such as B_d^0(t) -> D^{*\pm} \rho^\mp, D^{*\pm} a_1^{\mp}, D^{*0} K^{*0}, etc. Similarly, one can use B_s^0(t) -> D_s^{*\pm} K^{*\mp} to extract sin⁥2Îł\sin^2 \gamma. There are no penguin contributions to these decays. It is possible that sin⁥2(2ÎČ+Îł)\sin^2 (2\beta + \gamma) will be the second function of CP phases, after sin⁥2ÎČ\sin 2\beta, to be measured at B-factories.Comment: 4 pages, RevTeX, no figure

    Charmless B→PPB \to PP decays using flavor SU(3) symmetry

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    The decays of BB mesons to a pair of charmless pseudoscalar (PP) mesons are analyzed within a framework of flavor SU(3). Symmetry breaking is taken into account in tree (TT) amplitudes through ratios of decay constants; exact SU(3) is assumed elsewhere. Acceptable fits to B→ππB \to \pi \pi and B→KπB \to K \pi branching ratios and CP asymmetries are obtained with tree, color-suppressed (CC), penguin (PP), and electroweak penguin (PEWP_{EW}) amplitudes. Crucial additional terms for describing processes involving η\eta and ηâ€Č\eta' include a large flavor-singlet penguin amplitude (SS) as proposed earlier and a penguin amplitude PtuP_{tu} associated with intermediate tt and uu quarks. For the B+→π+ηâ€ČB^+ \to \pi^+ \eta' mode a term StuS_{tu} associated with intermediate tt and uu quarks also may be needed. Values of the weak phase Îł\gamma are obtained consistent with an earlier analysis of B→VPB \to VP decays, where VV denotes a vector meson, and with other analyses of CKM parameters.Comment: 26 pages, 1 figure. To be submitted to Phys. Rev. D. Reference update

    P and CP violation in B physics

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    While the Kobayashi--Maskawa single phase origin of CP violation passed its first crucial precision test in B→J/ψKSB\to J/\psi K_S, the chirality of weak bb-quark couplings has not yet been carefully tested. We discuss recent proposals for studying the chiral and CP-violating structure of these couplings in radiative and in hadronic B decays.Comment: 15 pages, talk at PASCOS'03, Tata Inst., Mumbai, Jan. 200

    Supersymmetric contributions to B -> D K and the determination of angle \gamma

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    We analyze supersymmetric contributions to B^- -> D^0 K^- and B^- ->\bar{D}^0 K^- processes. We investigate the possibility that supersymmetric CP violating phases can affect our determination for the angle \gamma in the unitary triangle of Cabibbo-Kobayashi-Maskaw mixing matrix. We calculate the gluino and chargino contributions to b--> u(\bar{c}s) and b-->c(\bar{u}s) transitions in a model independent way by using the mass insertion approximation method. We also revise the D^0 - \bar{D}^0 mixing constraints on the mass insertions between the first and second generations of the up sector. We emphasize that in case of negligible D^0 -\bar{D}^0 mixing, one should consider simultaneous contributions from more than one mass insertion in order to be able to obtain the CP asymmetries of these processes within their 1\sigma experimental range. However, with a large D^0-\bar{D}^0 mixing, one finds a significant deviation between the two asymmetries and it becomes natural to have them of order the central values of their experimental measurements.Comment: 20 page

    Taming the Penguin in the B0(t) -> Pi+Pi- CP-asymmetry: Observables and Minimal Theoretical Input

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    Penguin contributions, being not negligible in general, can hide the information on the CKM angle alpha coming from the measurement of the time-dependent B0(t) -> pi+pi- CP-asymmetry. Nevertheless, we show that this information can be summarized in a set of simple equations, expressing alpha as a multi-valued function of a single theoretically unknown parameter, which conveniently can be chosen as a well-defined ratio of penguin to tree amplitudes. Using these exact analytic expressions, free of any assumption besides the Standard Model, and some reasonable hypotheses to constrain the modulus of the penguin amplitude, we derive several new upper bounds on the penguin-induced shift |2alpha-2alpha_eff|, generalizing the recent result of Grossman and Quinn. These bounds depend on the averaged branching ratios of some decays (pi0pi0, K0K0bar, K+-pi-+) particularly sensitive to the penguin. On the other hand, with further and less conservative approximations, we show that the knowledge of the B+- -> Kpi+- branching ratio alone gives sufficient information to extract the free parameter without the need of other measurements, and without knowing |V_td| or |V_ub|. More generally, knowing the modulus of the penguin amplitude with an accuracy of ~30% might result in an extraction of alpha competitive with the experimentally more difficult isospin analysis. We also show that our framework allows to recover most of the previous approaches in a transparent and simple way, and in some cases to improve them. In addition we discuss in detail the problem of the various kinds of discrete ambiguities.Comment: LaTeX2e, 44 pages, 9 figures (from 18 postscript files) included with epsf. Minor changes, references updated. New CLEO results from ICHEP'98 are taken into account. To appear in Phys. Rev.
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