2,656 research outputs found
decays revisited: branching ratios and T-odd momenta correlations
We calculate the branching ratios of the decays, and the T-odd triple momenta correlations
, due to the
electromagnetic final state interaction, in these processes. The contributions
on the order of and to the corresponding amplitudes
are treated exactly. For the branching ratios, the corrections on the order of
are estimated and demonstrated to be small. We compare the results
with those of other authors. In some cases our results differ considerably from
the previous ones.Comment: 13 pages, 11 figures; references adde
Tracing CP-violation in Lepton Flavor Violating Muon Decays
Although the Lepton Flavor Violating (LFV) decay is
forbidden in the Standard Model (SM), it can take place within various theories
beyond the SM. If the branching ratio of this decay saturates its present bound
[{\it i.e.,} Br], the forthcoming
experiments can measure the branching ratio with high precision and
consequently yield information on the sources of LFV. In this letter, we show
that for polarized , by studying the angular distribution of the
transversely polarized positron and linearly polarized photon we can derive
information on the CP-violating sources beyond those in the SM. We also study
the angular distribution of the final particles in the decay where is defined to be the more energetic positron. We show
that transversely polarized can provide information on a certain
combination of the CP-violating phases of the underlying theory which would be
lost by averaging over the spin of .Comment: 6 pages, 2 figure
Wash-Out in N_2-dominated leptogenesis
We study the wash-out of a cosmological baryon asymmetry produced via
leptogenesis by subsequent interactions. Therefore we focus on a scenario in
which a lepton asymmetry is established in the out-of-equilibrium decays of the
next-to-lightest right-handed neutrino. We apply the full classical Boltzmann
equations without the assumption of kinetic equilibrium and including all
quantum statistical factors to calculate the wash-out of the lepton asymmetry
by interactions of the lightest right-handed state. We include scattering
processes with top quarks in our analysis. This is of particular interest since
the wash-out is enhanced by scatterings and the use of mode equations with
quantum statistical distribution functions. In this way we provide a
restriction on the parameter space for this scenarios.Comment: 26 pages, 4 figures, profound revision, exposition is now in flavor
notation, one plot and discussion added, numerical error corrected, three
plots changed, text polished, main results remain unchanged, reference
added,matches published versio
Glueball Production in Peripheral Heavy-Ion Collisions
The method of equivalent quanta is applied both to photon-photon and, by
analogy, to double pomeron exchange in heavy-ion collisions. This
Weizs\"acker-Williams approach is used to calculate production cross sections
for the glueball candidate meson via photon-photon and
pomeron-pomeron fusion in peripheral heavy-ion collisions at both RHIC and LHC
energies. The impact-parameter dependence for total and elastic cross sections
are presented, and are compared to results for proton-proton collisions.Comment: 15 pages, 6 figure
Mixing among light scalar mesons and L=1 q\bar{q} scalar mesons
Following the re-establishment of the \sigma(600) and the \kappa(900), the
light scalar mesons a_0(980) and f_0(980) together with the \sigma(600) and the
\kappa(900) are considered as the chiral scalar partner of pseudoscalar nonet
in SU(3) chiral symmetry, and the high mass scalar mesons a_0(1450),
K^*_0(1430), f_0(1370) and f_0(1710) turned out to be considered as the L=1
q\bar{q} scalar mesons. We assume that the high mass of the L=1 q\bar{q} scalar
mesons is caused by the mixing with the light scalar mesons. For the structure
of the light scalar mesons, we adopted the qq\bar{q}\bar{q} model in order to
explain the "scalar meson puzzle". The inter-mixing between the light scalar
nonet and the high mass L=1 q\bar{q} nonet and the intra-mixing among each
nonet are analyzed by including the glueball into the high mass scalar nonet.Comment: 16 pages, 5 figure
Hadronization of massive quark matter
We present a fast hadronization model for the constituent quark plasma (CQP)
produced in relativistic heavy ion collisions at SPS. The model is based on
rate equations and on an equation of state inspired by the string
phenomenology. This equation of state has a confining character. We display the
time evolution of the relevant physical quantities during the hadronization
process and the final hadron multiplicities. The results indicate that the
hadronization of CQP is fast.Comment: 12 pages, Latex, 2 EPS figures, contribution to the Proceedings of
the 4th International Conference on Strangeness in Quark Matter (SQM'98),
Padova, Italy, 20-24 July 199
Hyperon Nonleptonic Weak Decays Revisited
We first review the current algebra - PCAC approach to nonleptonic octet
baryon 14 weak decay B (\to) (B^{\prime})(\pi) amplitudes. The needed four
parameters are independently determined by (\Omega \to \Xi \pi),(\Lambda K) and
(\Xi ^{-}\to \Sigma ^{-}\gamma) weak decays in dispersion theory tree order. We
also summarize the recent chiral perturbation theory (ChPT) version of the
eight independent B (\to) (B^{\prime}\pi) weak (\Delta I) = 1/2 amplitudes
containing considerably more than eight low-energy weak constants in one-loop
order.Comment: 10 pages, RevTe
Towards resolution of the scalar meson nonet enigma
By the application of a linear mass spectrum to a composite system of both
the pseudoscalar and scalar meson nonets, we find three mass relations for the
masses of the scalar states which suggest the assignment for the
scalar meson nonet: Comment: 16 pages, LaTe
Production of Triply Charmed Baryons in Annihilation
The total and differential cross sections for the production of triply
charmed baryons in annihilation are calculated at
the -boson pole.Comment: 13 pages, 2 figure
Cosmological bounds on sub-MeV mass axions
Axions with mass greater than 0.7 eV are excluded by cosmological precision
data because they provide too much hot dark matter. While for masses above 20
eV the axion lifetime drops below the age of the universe, we show that the
cosmological exclusion range can be extended from 0.7 eV till 300 keV,
primarily by the cosmic deuterium abundance: axion decays would strongly modify
the baryon-to-photon ratio at BBN relative to the one at CMB decoupling.
Additional arguments include neutrino dilution relative to photons by axion
decays and spectral CMB distortions. Our new cosmological constraints
complement stellar-evolution limits and laboratory bounds.Comment: 19 pages, 10 figure
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