2,162 research outputs found

    Branching ratios and CP asymmetries in charmless nonleptonic B decays to radially excited mesons

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    Nonleptonic two body B decays including radially excited π(1300)\pi(1300) or ρ(1450)\rho(1450) mesons in the final state are studied using the framework of generalized naive factorization approach. Branching ratios and CP asymmetries of BPπ(1300)B\to P\pi(1300), BVπ(1300)B\to V\pi(1300), BPρ(1450)B\to P\rho(1450) and BVρ(1450)B\to V\rho(1450) decays are calculated, where P and V stand for pseudoscalar and vector charmless mesons. Form factors for Bπ(1300)B\to \pi(1300) and Bρ(1450)B\to \rho(1450) transitions are estimated in the improved version of the Isgur-Scora-Grinstein-Wise quark model. In some processes, CP asymmetries of more than 10% and branching ratios of 10510^{-5} order are found, which could be reached in experiments.Comment: 18 pages, 11 table

    B_s Mixing and B Hadron Lifetimes at CDF

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    We present the CDF results using 1.0 fb^{-1} of data on the mixing frequency measurement in the B_s system and the lifetime measurements of several B hadrons. We obtain \Delta m_s=17.77 +- 0.1 +- 0.07 ps^{-1} and c\tau(\Lambda_b)=473.8 +- 23.1 +- 3.5 \mu m. The later one is more than 3 sigma above the world average, but in reasonable agreement with HQE calculations.Comment: submitted to EPS2007 proceeding

    Measuring Bs Width Difference at the Upsilon(5s) Using Quantum Entanglement

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    About 90% of Bs-bar Bs pairs produced at the Upsilon(5s) resonance are initially Bs*-bar Bs* pairs which decay radiatively to Bs-bar Bs. This implies that the Bs pair will then be in an eigenstate of charge conjugation (i.e. C=-1) and therefore in an entangled state. This allows for a determination of Delta Gamma/Gamma and the CP phase using a number of possible correlations between the decays of the two Bs mesons. In particular, we consider the time integrated correlation; the time ordering asymmetry and the time ordering-charge asymmetry, which in addition to time ordering distinguishes Bs from Bs-bar, for various combinations of final states. With the statistics of about O(10^7-10^8) Upsilon(5s) events available at B factories, we find that the time ordering asymmetry between suitably defined hadronic and flavor specific (tagging) decays offers a promising method for determining the width difference. The corresponding time ordering-charge asymmetry can also bound the mixing phase. Similar observables involving exclusive decays are also considered. At the super B factories with O(50) times greater luminosity time ordering and time ordering-charge asymmetries between inclusive and exclusive modes may also provide additional bounds on the phases in those decays;Comment: no figures; Updated version: This is the version accepted by Phys Rev D; Some additional comments were added between equations 8 and 12, also reference 20 to recent D0 results was adde

    The Mass Definition in Hqet and a New Determination of Vcb_{\text{cb}}

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    Positive powers of the mass parameter in a physical quantity calculated with the help of heavy quark effective theory originate from a Wilson coefficient in the matching of QCD and HQET Green function. We show that this mass parameter enters the calculation as a well--defined running current mass. We further argue that the recently found ill--definition of the pole mass, which is the natural expansion parameter of HQET, does not affect a phenomenological analysis which uses truncated perturbative series. We reanalyse inclusive semileptonic decays of heavy mesons and obtain the cc quark mass mcMS(mc)=(1.35±0.20)GeVm_c^{\overline{\text{MS}}}(m_c) = (1.35\pm 0.20)\,\text{GeV} where the error is almost entirely due to scale--uncertainties. We also obtain mbMS(mb)=(4.6±0.3)GeVm_b^{\overline{\text{MS}}}(m_b) = (4.6\pm 0.3)\,\text{GeV} and Vcb(τB/1.49ps)1/2=0.036±0.005|V_{cb}|(\tau_B/1.49\,\text{ps})^{1/2} = 0.036\pm 0.005 where the errors come from the uncertainty in the kinetic energy of the heavy quark inside the meson, in the experimental branching ratios, in QCD input parameters, and scale--uncertainties.Comment: 21 p., 5 figs, all style files incl., TUM-T31-56/R (Sec. 2 revised, phenomenological results unchanged

    Subleading Shape-Function Effects and the Extraction of |V_ub|

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    We derive a class of formulae relating moments of B -> Xu l nu to B -> Xs gamma in the shape function region, where m_X^2 ~ m_b Lambda_QCD. We also derive an analogous class of formulae involving the decay B -> Xs l+ l-. These results incorporate Lambda_QCD/m_b power corrections, but are independent of leading and subleading hadronic shape functions. Consequently, they enable one to determine |V_ub|/|V_tb V_ts*| to subleading order in a model-independent way.Comment: 23 page

    Constraining weak annihilation using semileptonic D decays

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    The recently measured semileptonic D_s decay rate can be used to constrain weak annihilation (WA) effects in semileptonic D and B decays. We revisit the theoretical predictions for inclusive semileptonic D_{(s)} decays using a variety of quark mass schemes. The most reliable results are obtained if the fits to B decay distributions are used to eliminate the charm quark mass dependence, without using any specific charm mass scheme. Our fit to the available data shows that WA is smaller than commonly assumed. There is no indication that the WA octet contribution (which is better constrained than the singlet contribution) dominates. The results constrain an important source of uncertainty in the extraction of |Vub| from inclusive semileptonic B decays.Comment: 5 pages, 2 figures, published versio

    Hadron Spectra for Semileptonic Heavy Quark Decay

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    We calculate the leading perturbative and power corrections to the hadronic invariant mass and energy spectra in semileptonic heavy hadron decays. We apply our results to the BB system. Moments of the invariant mass spectrum, which vanish in the parton model, probe gluon bremsstrahlung and nonperturbative effects. Combining our results with recent data on BB meson branching ratios, we obtain a lower bound Λˉ>410MeV\bar\Lambda>410\,{\rm MeV} and an upper bound mbpole<4.89m_b^{\rm pole}<4.89\,GeV. The Brodsky-Lepage-Mackenzie scale setting procedure suggests that higher order perturbative corrections are small for bottom decay, and even tractable for charm decay.Comment: 24 pages, uses REVTeX, 5 EPS figures embedded with epsf.sty, slightly modified version to appear in Phys. Rev.

    CP Violation in D0D0D^0-\overline{D^0}Mixing

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    The existence of D0D0D^0-\overline{D^0} mixing at a detectable level requires new physics, which effectively yields a Δc=2\Delta c = 2 superweak interaction. In general this interaction may involve significant CP violation. For small values of the mixing it may be much easier to detect the CP-violating part of the mixing than the CP-conserving part.Comment: 3 pages, latex, no figure

    Conclusions from CDF Results on CP Violation in D^0 \to \pi^+\pi^-, K^+K^- and Future Tasks

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    Within the Standard Model (SM) one predicts both direct and indirect CP violation in D^0 \to \pi^+\pi^-, K^+K^- transitions, although the effects are tiny: Indirect CP asymmetry cannot exceed O(10^{-4}), probably even O(10^{-5}); direct effects are estimated at not larger than 10^{-4}. At B factories direct and indirect asymmetries have been studied with /\tau_{D^0} ~ 1; no CP asymmetry was found with an upper bound of about 1%. CDF has shown intriguing data on CP violation in D^0 \to \pi^+\pi^- [K^+K^-] with /\tau_{D^0} ~ 2.4 [2.65]. Also, CDF has not seen any CP violation. For direct CP asymmetry, CDF has a sensitivity similar to the combination of the B factories, yet for indirect CP violation it yields a significantly smaller sensitivity of a_{cp}^{ind}=(-0.01 +- 0.06_{stat} +- 0.05_{syst})% due to it being based on longer decay times. New Physics models (NP) like Little Higgs Models with T-Parity (LHT) can produce an indirect CP asymmetry up to 1%; CDF's findings thus cover the upper range of realistic NP predictions ~ 0.1 - 1%. One hopes that LHCb and a Super-Flavour Factory will probe the lower range down to ~0.01%. Such non-ad-hoc NP like LHT cannot enhance direct CP violation significantly over the SM level in D^0 \to \pi^+\pi^-, K^+K^- and D^{\pm} \to \pi^{\pm}K^+K^- transitions, but others might well do so.Comment: 11 pages, 1 figure. V2 has minor corrections and corresponds to the published versio

    Four-quark Operators Relevant to B Meson Lifetimes from QCD Sum Rules

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    At the order of 1/m_b^3, the B meson lifetimes are controlled by the hadronic matrix elements of some four-quark operators. The nonfactorizable magnitudes of these four-quark operator matrix elements are analyzed by QCD sum rules in the framework of heavy quark effective theory. The vacuum saturation for color-singlet four-quark operators is justified at hadronic scale, and the nonfactorizable effect is at a few percent level. However for color-octet four-quark operators, the vacuum saturation is violated sizably that the nonfactorizable effect cannot be neglected for the B meson lifetimes. The implication to the extraction of some of the parameters from B decays is discussed. The B meson lifetime ratio is predicted as \tau(B^-)/\tau(B^0)=1.09\pm 0.02. However, the experimental result of the lifetime ratio \tau(\Lambda_b)/\tau(B^0) still cannot be explained.Comment: 20 pages, latex, 6 figures, discussion on non-factorizable effect of the four-quark condensate added, to appear in Phys. Rev. D57 (1998
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