74 research outputs found
Charmless Three-body Decays of B Mesons
Charmless 3-body decays of B mesons are studied in the framework of the
factorization approach. The nonresonant contributions arising from transitions are evaluated using heavy meson chiral perturbation theory
(HMChPT). The momentum dependence of nonresonant amplitudes is assumed to be in
the exponential form e^{-\alpha_{NR}} p_B\cdot(p_i+p_j)} so that the HMChPT
results are recovered in the soft meson limit . In addition, we
have identified another large source of the nonresonant signal in the matrix
elements of scalar densities, e.g. , which can be
constrained from the decay or . The
intermediate vector meson contributions to 3-body decays are identified through
the vector current, while the scalar meson resonances are mainly associated
with the scalar density. Their effects are described in terms of the
Breit-Wigner formalism. Our main results are: (i) All KKK modes are dominated
by the nonresonant background. The predicted branching ratios of
, and modes are consistent with the
data within errors. (ii) Although the penguin-dominated
decay is subject to a potentially significant tree pollution, its effective
is very similar to that of the mode. However, direct
CP asymmetry of the former, being of order -4%, is more prominent than the
latter. (iii) For decays, we found sizable nonresonant
contributions in and modes, in agreement
with the Belle measurements but larger than the BaBar result.Comment: 39 pages, 2 figures, version to appear in PR
Simulation of neutrino and charged particle production and propagation in the atmosphere
A precise evaluation of the secondary particle production and propagation in
the atmosphere is very important for the atmospheric neutrino oscillation
studies. The issue is addressed with the extension of a previously developed
full 3-Dimensional Monte-Carlo simulation of particle generation and transport
in the atmosphere, to compute the flux of secondary protons, muons and
neutrinos. Recent balloon borne experiments have performed a set of accurate
flux measurements for different particle species at different altitudes in the
atmosphere, which can be used to test the calculations for the atmospheric
neutrino production, and constrain the underlying hadronic models. The
simulation results are reported and compared with the latest flux measurements.
It is shown that the level of precision reached by these experiments could be
used to constrain the nuclear models used in the simulation. The implication of
these results for the atmospheric neutrino flux calculation are discussed.Comment: 11 pages, 9 figure
Heavy--light mesons in a bilocal effective theory
Heavy--light mesons are described in an effective quark theory with a
two--body vector--type interaction. The bilocal interaction is taken to be
instantaneous in the rest frame of the bound state, but formulated covariantly
through the use of a boost vector. The chiral symmetry of the light flavor is
broken spontaneously at mean field level. The framework for our discussion of
bound states is the effective bilocal meson action obtained by bosonization of
the quark theory. Mesons are described by 3--dimensional wave functions
satisfying Salpeter equations, which exhibit both Goldstone solutions in the
chiral limit and heavy--quark symmetry for . We present
numerical solutions for pseudoscalar -- and --mesons. Heavy--light meson
spectra and decay constants are seen to be sensitive to the description of
chiral symmetry breaking (dynamically generated vs.\ constant quark mass).Comment: (34 p., standard LaTeX, 7 PostScript figures appended)
UNITUE-THEP-17/9
f [N pi N]: from quarks to the pion derivative coupling
We study the N pi N coupling, in the framework of a QCD-inspired confining
Nambu-Jona-Lasinio model. A simple relativistic confining and instantaneous
quark model is reviewed. The Salpeter equation for the nucleon and the boosted
pion is solved. The f [n pi n] and f[n pi Delta] couplings are calculated and
they turn out to be reasonably good. The sensibility of f[n pi n] and f[n pi
Delta] to confinement, chiral symmetry breaking and Lorentz invariance is
briefly discussed.Comment: 30 pages in LaTex RevTex, 6 postscript figure
Monopole Vacuum in Non-Abelian Theories
It is shown that, in the theory of interacting Yang -Mills fields and a Higgs
field, there is a topological degeneracy of Bogomol'nyi-Prasad-Sommerfield
(BPS) monopoles and that there arises, in this case, a chromoelectric monopole
characterized by a new topological variable that describes transitions between
topological states of the monopole in the Minkowski space (in just the same way
as an instanton describes such transitions in the Euclidean space). The limit
of an infinitely large mass of the Higgs field at a finite density of the BPS
monopole is considered as a model of the stable vacuum in the pure Yang-Mills
theory. It is shown that, in QCD, such a monopole vacuum may lead to a rising
potential, a topological confinement and an additional mass of the
meson. The relationship between the result obtained here for the generating
functional of perturbation theory and Faddeev-Popov integral is discussed
Repulsive Core of NN S-Wave Scattering in a Quark Model with a Condensed Vacuum
We work in a chiral invariant quark model, with a condensed vacuum,
characterized by only one parameter. Bound state equations for the nucleon and
Delta are solved in order to obtain an updated value of their radii and masses.
Nucleon-nucleon S-Wave scattering is studied in the RGM framework both for
isospin T=1 and T=0. The phase shifts are calculated and an equivalent local
potential, which is consistent with K-N scattering, is derived. The result is a
reasonable microscopic short range repulsion in the nucleon-nucleon
interaction.Comment: 23 pages in latex revtex, 4 Postscript figure
Heavy- to light-meson transition form factors
Semileptonic heavy -> heavy and heavy -> light meson transitions are studied
as a phenomenological application of a heavy-quark limit of Dyson-Schwinger
equations. Employing two parameters: E, the difference between the mass of the
heavy meson and the effective-mass of the heavy quark; and Lambda, the width of
the heavy-meson Bethe-Salpeter amplitude, we calculate f_+(t) for all decays on
their entire kinematically accessible t-domain. Our study favours f_B in the
range 0.135-0.17 GeV and with E=0.44 GeV and 1/Lambda = 0.14 fm we obtain
f_+^{B pi}(0) = 0.46. As a result of neglecting 1/m_c-corrections, we estimate
that our calculated values of \rho^2 = 0.87 and f_+^{DK}(0)=0.62 are too low by
approximately 15%. However, the bulk of these corrections should cancel in our
calculated values of Br(D -> \pi l nu)/Br(D -> K l nu)=0.13 and f_+^{D
pi}(0)/f_+^{DK}(0) = 1.16.Comment: 26 pages, 3 figures, REVTE
Atmospheric muon flux at PeV energies
In the near future the energy region above few hundreds of TeV may really be
accessible for measurements of the atmospheric muon spectrum by the IceCube
array. Therefore one expects that muon flux uncertainties above 50 TeV, related
to a poor knowledge of charm production cross sections and insufficiently
examined primary spectra and composition, will be diminished. We give
predictions for the very high-energy muon spectrum at sea level, obtained with
the three hadronic interaction models, taking into account also the muon
contribution due to decays of the charmed hadrons.Comment: 8 pages, 3 figures. The version published in Int. J. Mod. Phys.
Chiral symmetry breaking solutions for QCD in the truncated Coulomb gauge
In this paper we study the power-like confining potentials r^alpha. The
region of allowed alphas is identified, the mass-gap equation is constructed
for an arbitrary alpha and solved for several values of the latter, and the
vacuum energy and the chiral condensate are calculated. The question of replica
solutions to the mass-gap equation for such potentials is addressed and it is
demonstrated that the number of replicas is infinite for any alpha, as a
consequence of the peculiar behaviour of the quark self-energy in the infrared
domain.Comment: RevTeX4, 18 pages, 3 Postscript figures, uses epsfig.sty, to appear
in Phys.Rev.
EXAMINATION AND TESTING OF EXPERIMENTAL-PRODUCTION SERIES OF POLYVALENT BRUCELLOSIS SERUM
At present no commercial polyvalent brucellosis serum is produced in Russia. We developed a technology of polyvalent brucellosis high-effective and specific serum production without adsorption. Experimental-production series are obeyed the technical specification project
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