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Title: Quark model study of the semileptonic B {yields} {pi} decay

Abstract

The semileptonic decay B {yields} {pi}l{nu}-barl is studied starting from a simple quark model and taking into account the effect of the B* resonance. A novel, multiply subtracted, Omnes dispersion relation has been implemented to extend the predictions of the quark model to all physical q2 values. We find |Vub| = 0.0034 {+-} 0.0003(exp.) {+-} 0.0007(theory), in good agreement with experiment.

Authors:
;  [1]; ;  [2];  [3]
  1. School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom)
  2. Grupo de Fisica Nuclear, Departamento de Fisica Fundamental e IUFFyM, Universidad de Salamacanca, E-37008 Salamanca (Spain)
  3. Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada (Spain)
Publication Date:
OSTI Identifier:
21056841
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 892; Journal Issue: 1; Conference: QCHS7: 7. conference on quark confinement and the hadron spectrum, Ponta Delgada, Acores (Portugal), 2-7 Sep 2006; Other Information: DOI: 10.1063/1.2714403; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; B MESONS; DISPERSION RELATIONS; NEUTRINOS; PARTICLE PRODUCTION; PIONS; QUARK MODEL; RESONANCE PARTICLES; SEMILEPTONIC DECAY

Citation Formats

Albertus, C., Flynn, J. M., Hernandez, E., Verde-Velasco, J. M., and Nieves, J. Quark model study of the semileptonic B {yields} {pi} decay. United States: N. p., 2007. Web. doi:10.1063/1.2714403.
Albertus, C., Flynn, J. M., Hernandez, E., Verde-Velasco, J. M., & Nieves, J. Quark model study of the semileptonic B {yields} {pi} decay. United States. doi:10.1063/1.2714403.
Albertus, C., Flynn, J. M., Hernandez, E., Verde-Velasco, J. M., and Nieves, J. Tue . "Quark model study of the semileptonic B {yields} {pi} decay". United States. doi:10.1063/1.2714403.
@article{osti_21056841,
title = {Quark model study of the semileptonic B {yields} {pi} decay},
author = {Albertus, C. and Flynn, J. M. and Hernandez, E. and Verde-Velasco, J. M. and Nieves, J.},
abstractNote = {The semileptonic decay B {yields} {pi}l{nu}-barl is studied starting from a simple quark model and taking into account the effect of the B* resonance. A novel, multiply subtracted, Omnes dispersion relation has been implemented to extend the predictions of the quark model to all physical q2 values. We find |Vub| = 0.0034 {+-} 0.0003(exp.) {+-} 0.0007(theory), in good agreement with experiment.},
doi = {10.1063/1.2714403},
journal = {AIP Conference Proceedings},
number = 1,
volume = 892,
place = {United States},
year = {Tue Feb 27 00:00:00 EST 2007},
month = {Tue Feb 27 00:00:00 EST 2007}
}
  • The semileptonic B{yields}{pi}l{sup +}{nu}{sub l} decay is studied starting from a simple quark model which includes the influence of the B* pole. To extend the predictions of a nonrelativistic constituent quark model from its region of applicability near q{sub max}{sup 2}=(m{sub B}-m{sub {pi}}){sup 2} to all q{sup 2} values accessible in the physical decay, we use a novel multiply subtracted Omnes dispersion relation, which considerably diminishes the form-factor dependence on the elastic {pi}B{yields}{pi}B scattering amplitudes at high energies. By comparison to the experimental branching fraction we extract |V{sub ub}|=0.0034{+-}0.0003(exp){+-}0.0007(theory). To further test our framework, we also study D{yields}{pi} and D{yields}Kmore » decays and find excellent results f{sub {pi}}{sup +}(0)/f{sub K}{sup +}(0)=0.80{+-}0.03, B(D{sup 0}{yields}{pi}{sup -}e{sup +}{nu}{sub e})/B(D{sup 0}{yields}K{sup -}e{sup +}{nu}{sub e})=0.079{+-}0.008. In particular for the D{yields}{pi} case, we reproduce, with high accuracy, the three-flavor lattice QCD results recently obtained by the Fermilab-MILC-HPQCD Collaboration. While for the D{yields}K case, we successfully describe the data for f{sup +}(q{sup 2})/f{sup +}(0) recently measured by the FOCUS Collaboration.« less
  • According to heavy-meson chiral perturbation theory, the vector form factor f{sub +}(q{sup 2}) of exclusive semileptonic decay B{yields}{pi}l{nu} is closely related, at least in the soft-pion region (i.e., q{sup 2{approx}}(m{sub B}-m{sub {pi}}){sup 2}), to the strong coupling g{sub B*B{pi}} or the normalized coupling g-circumflex. Combining the precisely measured q{sup 2} spectrum of B{yields}{pi}l{nu} decay by the BABAR and Belle collaborations with several parametrizations of the form factor f{sub +}(q{sup 2}), we can extract these couplings from the residue of the form factor at the B{sup *} pole, which relies on an extrapolation of the form factor from the semileptonic regionmore » to the unphysical point q{sup 2}=m{sub B}{sup *2}. Comparing the extracted values with the other experimental and theoretical estimates, we can test these various form-factor parametrizations, which differ from each other by the amount of physical information embedded in. It is found that the extracted values based on the Becirevic-Kaidalov, Ball-Zwicky and Bourrely-Caprini-Lellouch parametrizations are consistent with each other and roughly in agreement with the other theoretical and lattice estimates, while the Boyd-Grinstein-Lebed ansatz, featured by a spurious, unwanted pole at the threshold of the cut, gives a neatly larger value.« less
  • We present the results of a nonrelativistic constituent quark model study of the semileptonic decays {lambda}{sub b}{sup 0}{yields}{lambda}{sub c}{sup +}l{sup -}{nu}{sub l} and {xi}{sub b}{sup 0}{yields}{xi}{sub c}{sup +}l{sup -}{nu}{sub l} (l=e,{mu}). We work on coordinate space, with baryon wave functions recently obtained from a variational approach based on heavy quark symmetry. We develop a novel expansion of the electroweak current operator, which supplemented with heavy quark effective theory constraints, allows us to predict the baryon form factors and the decay distributions for all q{sup 2} (or equivalently w) values accessible in the physical decays. Our results for the partially integratedmore » longitudinal and transverse decay widths, in the vicinity of the w=1 point, are in excellent agreement with lattice calculations. Comparison of our integrated {lambda}{sub b}-decay width to experiment allows us to extract the V{sub cb} Cabbibo-Kobayashi-Maskawa matrix element for which we obtain a value of |V{sub cb}|=0.040{+-}0.005(stat){sub -0.002}{sup +0.001}(theory) also in excellent agreement with a recent determination by the DELPHI Collaboration from the exclusive B{sub d}{sup 0}{yields}D*{sup +}l{sup -}{nu}{sub l} decay. Besides for the {lambda}{sub b}({xi}{sub b})-decay, the longitudinal and transverse asymmetries and the longitudinal to transverse decay ratio are <a{sub L}>=-0.954{+-}0.001(-0.945{+-}0.002), <a{sub T}>=-0.665{+-}0.002(-0.628{+-}0.004), and R{sub L/T}=1.63{+-}0.02(1.53{+-}0.04), respectively.« less
  • Using e{sup +}e{sup -}{yields}D{sub s}{sup -}D{sub s}*{sup +} and D{sub s}*{sup -}D{sub s}{sup +} interactions at 4170 MeV collected with the CLEO-c detector, we investigate the semileptonic decays D{sub s}{sup +}{yields}f{sub 0}(980)e{sup +}{nu} and D{sub s}{sup +}{yields}{phi}e{sup +}{nu}. By examining the decay rates as functions of the four-momentum transfer squared q{sup 2}, we measure the ratio [(dB/dq{sup 2})(D{sub s}{sup +}{yields}f{sub 0}(980)e{sup +}{nu})B(f{sub 0}{yields}{pi}{sup +}{pi}{sup -})]/[(dB/dq{sup 2})(D{sub s}{sup +}{yields}{phi}e{sup +}{nu})B({phi}{yields}K{sup +}K{sup -})] at q{sup 2} of zero to be (42{+-}11)%. This ratio has been predicted to equal the rate ratio [B(B{sub s}{yields}J/{psi}f{sub 0})B(f{sub 0}{yields}{pi}{sup +}{pi}{sup -})]/[B(B{sub s}{yields}J/{psi}{phi})B({phi}{yields}K{sup +}K{sup -})], thus indicatingmore » that the CP eigenstate J/{psi}f{sub 0} could be useful for measuring CP violation via B{sub s} mixing. Assuming a simple pole model for the form factor |f{sub +}(q{sup 2})| in the f{sub 0}e{sup +}{nu} decay, we find a pole mass of (1.7{sub -0.7}{sup +4.5}{+-}0.2) GeV. We also determine the f{sub 0} mass and width as (977{sub -9}{sup +11}{+-}1) and (91{sub -22}{sup +30}{+-}3) MeV, respectively. In addition, we present updated results for B(D{sub s}{sup +}{yields}f{sub 0}(980)e{sup +}{nu})B(f{sub 0}{yields}{pi}{sup +}{pi}{sup -})=(0.20{+-}0.03{+-}0.01)% and B(D{sub s}{sup +}{yields}{phi}e{sup +}{nu})=(2.36{+-}0.23{+-}0.13)%. Assuming that the f{sub 0} wave function is a combination of strange and nonstrange quark-antiquark components, we use our measurement for B(D{sub s}{sup +}{yields}f{sub 0}(980)e{sup +}{nu}) to extract a value of the mixing angle that we find consistent with |ss> dominance, adding to the mystery as to why the f{sub 0} decays predominantly to two pions rather than two kaons.« less
  • We present updated measurements of the branching fractions and CP asymmetries for B{sup 0}{yields}{pi}{sup 0}{pi}{sup 0}, B{sup {+-}}{yields}{pi}{sup {+-}}{pi}{sup 0}, and B{sup {+-}}{yields}K{sup {+-}}{pi}{sup 0}. Based on a sample of 383x10{sup 6} {upsilon}(4S){yields}BB decays collected by the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC, we measure B(B{sup 0}{yields}{pi}{sup 0}{pi}{sup 0})=(1.47{+-}0.25{+-}0.12)x10{sup -6}, B(B{sup {+-}}{yields}{pi}{sup {+-}}{pi}{sup 0})=(5.02{+-}0.46{+-}0.29)x10{sup -6}, and B(B{sup {+-}}{yields}K{sup {+-}}{pi}{sup 0})=(13.6{+-}0.6{+-}0.7)x10{sup -6}. We also measure the CP asymmetries C{sub {pi}{sup 0}}{sub {pi}{sup 0}}=-0.49{+-}0.35{+-}0.05, A{sub {pi}{sup {+-}}}{sub {pi}{sup 0}}=0.03{+-}0.08{+-}0.01, and A{sub K{sup {+-}}}{sub {pi}{sup 0}}=0.030{+-}0.039{+-}0.010. Finally, we present bounds on the Cabibbo-Kobayashi-Maskawa angle {alpha} using isospin relations.