14,576 research outputs found
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
Monte Carlo simulations of the halo white dwarf population
The interpretation of microlensing results towards the Large Magellanic Cloud
(LMC) still remains controversial. Whereas white dwarfs have been proposed to
explain these results and, hence, to contribute significantly to the mass
budget of our Galaxy, there are as well several constraints on the role played
by white dwarfs. In this paper we analyze self-consistently and simultaneously
four different results, namely, the local halo white dwarf luminosity function,
the microlensing results reported by the MACHO team towards the LMC, the
results of Hubble Deep Field (HDF) and the results of the EROS experiment, for
several initial mass functions and halo ages. We find that the proposed
log-normal initial mass functions do not contribute to solve the problem posed
by the observed microlensing events and, moreover, they overproduce white
dwarfs when compared to the results of the HDF and of the EROS survey. We also
find that the contribution of hydrogen-rich white dwarfs to the dynamical mass
of the halo of the Galaxy cannot be more than .Comment: 17 pages, 10 figures; accepted for publication in Astronomy and
Astrophysic
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 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
Generalized Slow Roll Conditions and the Possibility of Intermediate Scale Inflation in Scalar-Tensor Theory
Generalized slow roll conditions and parameters are obtained for a general
form of scalar-tensor theory (with no external sources), having arbitrary
functions describing a nonminimal gravitational coupling F(\phi), a Kahler-like
kinetic function k(\phi), and a scalar potential V(\phi). These results are
then used to analyze a simple toy model example of chaotic inflation with a
single scalar field \phi and a standard Higgs potential and a simple
gravitational coupling function. In this type of model inflation can occur with
inflaton field values at an intermediate scale of roughly 10^{11} GeV when the
particle physics symmetry breaking scale is approximately 1 TeV, provided that
the theory is realized within the Jordan frame. If the theory is realized in
the Einstein frame, however, the intermediate scale inflation does not occur.Comment: 14 pages, no figs. Accepted to Classical and Quantum Gravit
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