Decays Of Bottom Mesons Research Articles

A study of ΔC = 1 decays of bottom mesons involving axial-vector meson

We study the two-body charmed nonleptonic weak decays of the bottom meson to an axial-vector meson and a pseudoscalar meson using the non-relativistic quark model. We employ the factorization hypothesis to obtain the branching ratios of these decays. First, we calculate the axial-vector (JP=1+) emitting form factors for B→D1/D_1 transitions in the non-relativistic Isgur-Scora-Grinstein-Wise quark model. Later, we use the heavy quark symmetry constraints to obtain the B→D11/2/D13/2 form factors and consequently, calculated their branching ratios. For a comparative analysis, we extract τ1/2(ω) and τ3/2(ω) form factors from the recent lattice QCD results to get a qualitative estimate of B→D11/2/D13/2 form factors. We find that the calculated branching ratios are in fair agreement with the available experimental data in both the scenarios. Also, we observe that, despite of 1/mQ suppression in heavy quark limit, the color-suppressed contribution to these decays can not be ignored.

Wave functions and leptonic decays of bottom mesons in the relativistic potential model

We study the wave functions and purely leptonic decays of $b$-flavored mesons (pseudoscalars, vector mesons, and higher excited states that are well established in experiment) in the relativistic potential model based on our previous works. The wave functions are obtained by solving the wave equation including the spin-spin and spin-orbit corrections in the effective potential. The decay constants of $B$, $B^*$ and some of their excited states that have been found in experiment are calculated with these wave functions. Then the branching fractions of the purely leptonic decay modes of these bottom mesons are studied. Our results are in well agreement with experiment data for decay modes that have been measured in experiments. We also provide predictions for some yet unmeasured channels, which are useful for experimental test in the future.

Estimating the production rates of D -wave charmed mesons via the semileptonic decays of bottom mesons * * Supported by the National Natural Science Foundation of China (11222547, 11175073, 11647301), the National Program for Support of Top-notch Young Professionals and the Fundamental Research Funds for the Central Universities

Using the covariant light-front approach with conventional vertex functions, we estimate the production rates of D -wave charmed/charmed-strange mesons via the semileptonic decays. As the calculated production rates are significant, it seems possible to experimentally search for D -wave charmed/charmed-strange mesons via semileptonic decays, which may provide an additional approach for exploring D -wave charmed/charmed-strange mesons.

Study of the Generalized Isotonic Oscillators Interaction in Semileptonic Decays of Bottom Mesons and Baryons

We have used mesonic and baryonic wave functions in the presence of the modified quantum isotonic oscillator interaction to compute the parameters of the Isgur–Wise function. Thereby we have presented branching ratios for mesons B and \(B_{s}\), decay widths of baryons \(\Lambda _b \), \(\Omega _b\), \({\vert }V_{cb}{\vert }\) for B and \(B_{s}\) semileptonic decays by using of differential decay width and Isgur–Wise functions. The results are in good agreement with experimental data and the other theoretical values.

Inclusive weak decays of heavy hadrons with power suppressed terms at NLO

Within the heavy quark expansion techniques for the heavy hadron weak decays we analytically compute the coefficient of the power suppressed dimension five chromo-magnetic operator at next-to-leading order of QCD perturbation theory with the full dependence on the final state quark mass. We present explicit expressions for the total width of inclusive semileptonic decays including the power suppressed terms and for a few moments of decay differential distributions. One of the important phenomenological applications of our results is precision analysis of the decays of bottom mesons to charmed final states and extraction of the numerical value for the CKM matrix entry |V_{cb}|.

Inclusive semileptonic B decays from QCD with NLO accuracy for power-suppressed terms

We present the results of a calculation of the perturbative QCD corrections for the semileptonic inclusive width of a heavy flavored meson. Within the Heavy Quark Expansion we analytically compute the QCD correction to the coefficient of power-suppressed contribution of chromo-magnetic operator in the limit of vanishing mass of the final state quark. The important phenomenological applications are decays of bottom mesons, and to the lesser extent, charmed mesons.

Decay constants and form factors of s-wave and p-wave mesons in the covariant light-front quark model

We reanalyze the decay constants of s-wave and p-wave mesons and the D, B → M form factors, where M represents a pseudoscalar meson, a vector meson, a scalar meson or an axial vector meson within a covariant light-front quark model. The parameter β for wavefunctions of most of s-wave mesons and that of a few axial-vector mesons are fixed with the latest experimental information, wherever available or using the lattice calculations. The treatment of masses and mixing angles for strange axial vector mesons is improved for the purpose. We extend our analysis to determine the form factors appearing in the Ds, Bs → M transitions, and to the isoscalar final state mesons. Numerical results of the form factors for transitions between a heavy pseudoscalar meson and an s-wave or a p-wave light meson and their momentum dependence are presented in detail. Further, their sensitivity to uncertainties of the β parameters of the initial as well as the final mesons is investigated. Some experimental measurements of the charmed and bottom meson decays are employed to compare the decay constants and transition form factors obtained in this and other works.

QCD FACTORIZATION BASED ON SIX-QUARK OPERATOR EFFECTIVE HAMILTONIAN FROM PERTURBATIVE QCD AND CHARMLESS BOTTOM MESON DECAYS B(s)→ππ, πK, KK

The charmless bottom meson decays are systematically investigated based on an approximate six-quark operator effective Hamiltonian from perturbative QCD. It is shown that within this framework the naive QCD factorization method provides a simple way to evaluate the hadronic matrix elements of two-body mesonic decays. The singularities caused by on mass-shell quark propagator and gluon exchanging interaction are appropriately treated. Such a simple framework allows us to make theoretical predictions for the decay amplitudes with reasonable input parameters. The resulting theoretical predictions for all the branching ratios and CP asymmetries in the charmless B0, B+, Bs → ππ, πK, KK decays are found to be consistent with the current experimental data except for a few decay modes. The observed large branching ratio in B→π0π0 decay remains a puzzle though the predicted branching ratio may be significantly improved by considering the large vertex corrections in the effective Wilson coefficients. More precise measurements of charmless bottom meson decays, especially on CP violations in B → KK and Bs → ππ, πK, KK decay modes, will provide a useful test and guide us to a better understanding on perturbative and nonperturbative QCD.

RICH counters for b-experiments

The paper reviews the motivation and status of ring imaging Cerenkov (RICH) counters for Belle and BaBar, experiments at e+e– B-factories, as well as their upgrades. PACS: 29.40.Ka Cherenkov detectors – 13.25.Hw Decays of bottom mesons

Prospects for pentaquark production at meson factories

Following Rosner [hep-ph/0312269], we consider B-decay production channels for the exotic I=0 and I=3/2 pentaquarks that have been recently reported. We also discuss new search channels for isovector pentaquarks, such as the Θ∗++(s̄duuu), that are generically present in chiral soliton models but were not observed in recent experiments. Furthermore, we argue that weak decays of charmed baryons, such as the Λc+ and Ξc0, provide another clean way of detecting exotic baryons made of light quarks only. We also discuss discovery channels for charmed pentaquarks, such as the isosinglet Θc0(c̄udud), in weak decays of bottom mesons and baryons. Finally, we discuss prospects for inclusive production of pentaquarks in e+e− collisions, with associated production of particles carrying the opposite baryon number.

Time-dependent CP violation in B0→ K0 s φ, $K^0_s\eta'$ and K0 s K+ K– in the Belle and BaBar experiments

Both the Belle and BaBar collaborations have recently measured time-dependent CP violation in B0 decays to $ss\overline{s}$ states and compared the results to those for $sc\overline{c}$ states for which quite precise results were previously available. Within the framework of the standard model the same results should be expected for both cases. The decays to $ss\overline{s}$ states are dominated by penguin diagrams and may be sensitive to physics beyond the standard model. For these states, compared to the results for $sc\overline{c}$ states, a discrepancy in the mixing-induced CP violation of 2.7 standard deviations was found, and may be interpreted as an indication for physics beyond the standard model. PACS: 11.30.Er Charge conjugation, parity, time reversal, andother discrete symmetries – 12.15.Hh Determination of Kobayashi-Maskawa matrix elements – 13.25.Hw Decays of bottom mesons

Rare hadronic B decays from BaBar

A selection of rare decay results from BaBar are presented, from a data sample of 82fb–1 of data taken at the Υ (4S) resonance (corresponding to 88× 106 $B\overline{B}$ pairs). PACS: 13.25.Hw Decays of bottom mesons

|V cb |, |V ub |, and HQET at CLEO

I report results from the CLEO collaboration on semileptonic B decays, highlighting measurements of the Cabibbo-Kobayashi-Maskawa matrix elements |V cb | and |V ub |. I describe the techniques used to obtain the recent improvements in precision for these measurements, including the use of the b→ sγ photon spectrum to reduce hadronic uncertainties in semileptonic B decays. I also report new measurements of |V cb | using the inclusive semileptonic branching fraction ${\cal B}(B\to X e \nu)$ and of |V ub | through study of the q2 dependence of B→πℓν and B→ρℓν. PACS: 12.15.Hh Determination of Kobayashi-Maskawa matrix elements – 13.20.He Decays of bottom mesons

Charmless B decays from CLEO: Rare and not-so-rare

We present updated results from the CLEO collaboration from two studies of B meson decay to charmless hadronic final states. In the first analysis, we combine data from the CLEO II and CLEO III detectors to provide final measurements of thirteen two-body decay modes. In the second, the combined CLEO II and CLEO II.V data set is used to determine the $\eta'$ momentum spectrum and branching ratio in the inclusive process $B\to \eta' X_{nc}$ ; with a more powerful analysis technique than was previously used. For the momentum range $2.0<P_{\eta'}< 2.7$ GeV/c , we find a branching ratio, ${\cal B}(B \to \eta'X_{nc})$ , of [4.6± 1.1± 0.4± 0.5] × 10–4. The uncertainties are statistical, systematic, and due to subtraction of charm-decay background, respectively. PACS: 13.25.Hw Decays of Bottom Mesons

Indications for large rescattering in rare B decays

The sign of ACP(K–π+) < 0, the evidence for $\bar B^0 \to \pi^0\pi^0$ , and the possibly sizable A π π and S π π in $\bar B^0 \to \pi^+\pi^-$ all suggest that final state rescattering may be needed in $\bar B\to PP$ decay, which is echoed by large color suppressed $\bar B^0\to D^0h^0$ modes. An SU(3) formalism of $\mbox{\bf 8}\otimes \mbox{\bf 8} \to \mbox{\bf 8}\otimes \mbox{\bf 8}$ rescattering in PP final states leads to interesting predictions, in particular allowing for small $\bar B^0 \to K^-K^+$ . PACS: 11.30.Hv Flavor symmetries – 13.25.Hw Decays of bottom mesons

B decays into charm at CLEO

Recent measurements of the branching fractions and helicity amplitudes of the decays B–→ D⋆ 0 ρ– and ${\bar B}^0 \to D^{\star +} \rho^{-}$ by the CLEO collaboration are presented. The fraction of longitudinal polarization in the ${\bar B}^0 \to D^{\star +} \rho^{-}$ decay is found to be consistent with the factorization hypothesis, although the helicity amplitudes show evidence for nonzero final-state interaction phases. PACS: 13.25.Hw Decays of bottom mesons – 12.39.St Factorization – 14.40.Nd Bottom mesons

Non-Leptonic Two-Meson Decays of B Mesons in the Covariant Oscillator Quark Model with Factorization Ansatz

Exclusive nonleptonic bottom meson decays are studied in the covariant osillator quark model using the factorization assumption. The main feature of this model is that it can simultaniously be applied to both heavy to heavy and heavy to light transitions, satisfying the constraints of the heavy quark effective theory (HQET) in the appropriate limit. The results obtained are in overall agreement with the present experimental data for various B decays.

Decay of the bottom mesons

The channels of the decay of bottom mesons are deduced from a selection rule and the Lagrangians which are formed on theL⊗O(4) invariance and the principle of minimal structure. The estimate of the corresponding decay probabilities is considered.

Spin, helicity and flavour patterns in exclusive decays of bottom mesons into baryon-antibaryon pairs

I use the constituent quark model to calculate the exclusive decays of bottom mesons into ground state baryon-antibaryon pairs mediated by the weakb→c and b→u transitions. TheW-exchange contributions to these decays are found to be negligible. For theW-decay contributions I find that the simple colour-flavour structure of the 1/2+ and 3/2+ ground state baryons together with the current-current nonleptonic Hamiltonian leads to many simple and testable predictions. Notable among these is the predicted vanishing of decays involving 3/2+ baryons as in\(\overline {B^0 } (B^ - ) \to 3/2^ + \overline {1/2^ + } \) and\(\overline {B^0 } (B^ - ) \to 3/2^ + \overline {3/2^ + } \). An experimental verification of these selection rules would test the chirality of the basicb→c andb→u transitions. I also derive predictions for the polarization of the final state baryons depending on the assumed mechanism of quark pair creation. These predictions can be checked in the cases where the final state baryons are weakly decaying spin 1/2 hyperons and charmed baryons.

Charmless decays of bottom mesons and a fourth generation.

B decays to charmless inclusive final states are discussed. The generic process is the loop-induced b\ensuremath{\rightarrow}${\mathrm{sg}}^{\mathrm{*}}$, ${g}^{\mathrm{*}}$ being an on-shell or off-shell gluon. We include the cases when the gluon momentum is lightlike, timelike, and spacelike. The timelike case includes ${g}^{\mathrm{*}}$\ensuremath{\rightarrow}qq\ifmmode\bar\else\textasciimacron\fi{} and gg splitup. Our findings are as follows: (1) B(b\ensuremath{\rightarrow}${\mathrm{sg}}^{\mathrm{*}}$)\ensuremath{\simeq}1% for three generations; (2) an experimental observation of charmless branching ratio \ensuremath{\ge}5% would (conservatively) imply the possibility of a fourth generation; and (3) charmless branching ratio &gt;20% would be difficult to accomodate in the standard model even with four families.