692 research outputs found
V_{us} from hyperon semileptonic decays
A model-independent determination of the CKM matrix element V_{us} from five
measured strangeness-changing hyperon semileptonic decays is performed. Flavor
SU(3) symmetry breaking effects in the leading vector and axial-vector form
factors are analyzed in the framework of the 1/N_c expansion of QCD. A fit to
experimental data allows one to extract the value V_{us}=0.2199\pm 0.0026,
which is comparable to the one from K_{e3} decays. This reconciliation is
achieved through second-order symmetry breaking effects of a few percent in the
form factors f_1, which increase their magnitudes over their SU(3) predictions.Comment: 23 pages, Revtex4, 12 tables, no figure
Precision radiative corrections to the Dalitz plot of baryon semileptonic decays including the spin-momentum correlation of the decaying baryon and the emitted charged lepton
We calculate the radiative corrections to the angular correlation between the
polarization of the decaying baryon and the direction of the emitted charged
lepton in the semileptonic decays of spin one-half baryons to order
(\alpha/\pi)(q/M_1). The final results are presented, first, with the triple
integration of the bremsstrahlung photon ready to be performed numerically and,
second, in an analytical form. A third presentation of our results in the form
of numerical arrays of coefficients to be multiplied on the quadratic products
of form factors is discussed. This latter may be the most practical one to use
in Monte Carlo simulations. A series of crosschecks is performed. The results
are useful in the analysis of the Dalitz plot of precision experiments
involving light and heavy quarks and is not compromised to fixing the form
factors at predetermined values. It is assumed that the real photons are
kinematically discriminated. Otherwise, our results have a general
model-independent applicability.Comment: 8 pages, RevTex4, 5 tables, no figures. Shortened version; results
and conclusions remain unchange
Precision radiative corrections to the semileptonic Dalitz plot with angular correlation between polarized decaying and emitted baryons: Effects of the four-body region
Analytical radiative corrections of order (\alpha/\pi)(q/M_1) are calculated
for the four-body region of the Dalitz plot of baryon semileptonic decays when
the s_1 \cdot p_2 correlation is present. Once the final result is available,
it is possible to exhibit it in terms of the corresponding final result of the
three-body region following a set of simple changes in the latter. We cover two
cases, a charged and a neutral polarized decaying baryon.Comment: Revtex4, 7 pages, no figure
Radiative corrections to all charge assignments of heavy quark baryon semileptonic decays
In semileptonic decays of spin-1/2 baryons containing heavy quarks up to six
charge assignments for the baryons and lepton are possible. We show that the
radiative corrections to four of these possibilities can be directly obtained
from the final results of the two possibilities previously studied. There is no
need to recalculate integrals over virtual or real photon momentum or any
traces.Comment: 15 pages, 2 figures, RevTex. Extended discussion. Final version to
appear in Physical Review
Radiative corrections to the three-body region of the Dalitz plot of baryon semileptonic decays with angular correlation between polarized emitted baryons and charged leptons: The initial-baryon rest frame case
We complement the results for the radiative corrections to the s2.l angular
correlation of baryon semileptonic decays of Ref. [1] with the final results in
the rest frame of the decaying baryon.Comment: 7 pages, Revtex4, no figure
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