861 research outputs found
A SUSY SU(5) Grand Unified Model of Tri-Bimaximal Mixing from A4
We discuss a grand unified model based on SUSY SU(5) in extra dimensions and
on the flavour group A4xU(1) which, besides reproducing tri-bimaximal mixing
for neutrinos with the accuracy required by the data, also leads to a natural
description of the observed pattern of quark masses and mixings.Comment: 19 page
Perturbative QCD analysis of decays
We study the first observed charmless modes, the
decays, in perturbative QCD formalism. The obtained branching ratios
are larger than
from QCD factorization. The comparison of the predicted magnitudes and phases
of the different helicity amplitudes, and branching ratios with experimental
data can test the power counting rules, the evaluation of annihilation
contributions, and the mechanism of dynamical penguin enhancement in
perturbative QCD, respectively.Comment: 14 pages, 2 tables, brief disscussion on hard sacle added, version to
appear in PR
Final state interaction and decays in perturbative QCD
We predict branching ratios and CP asymmetries of the decays using
perturbative QCD factorization theorem, in which tree, penguin, and
annihilation contributions, including both factorizable and nonfactorizable
ones, are expressed as convolutions of hard six-quark amplitudes with universal
meson wave functions. The unitarity angle and the and
meson wave functions extracted from experimental data of the and
decays are employed. Since the decays are sensitive to
final-state-interaction effects, the comparision of our predictions with future
data can test the neglect of these effects in the above formalism. The CP
asymmetry in the modes and the
branching ratios depend on annihilation and nonfactorizable amplitudes. The
data can also verify the evaluation of these contributions.Comment: 13 pages in latex file, 7 figures in ps file
Mass measurements of neutron-deficient Y, Zr, and Nb isotopes and their impact on rp and Îœp nucleosynthesis processes
© 2018 The Authors. Published by Elsevier B.V. This manuscript is made available under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International licence (CC BY-NC-ND 4.0). For further details please see: https://creativecommons.org/licenses/by-nc-nd/4.0/Using isochronous mass spectrometry at the experimental storage ring CSRe in Lanzhou, the masses of 82Zr and 84Nb were measured for the first time with an uncertainty of âŒ10 keV, and the masses of 79Y, 81Zr, and 83Nb were re-determined with a higher precision. The latter are significantly less bound than their literature values. Our new and accurate masses remove the irregularities of the mass surface in this region of the nuclear chart. Our results do not support the predicted island of pronounced low α separation energies for neutron-deficient Mo and Tc isotopes, making the formation of ZrâNb cycle in the rp-process unlikely. The new proton separation energy of 83Nb was determined to be 490(400) keV smaller than that in the Atomic Mass Evaluation 2012. This partly removes the overproduction of the p-nucleus 84Sr relative to the neutron-deficient molybdenum isotopes in the previous Îœp-process simulations.Peer reviewe
A CsI(Tl) Scintillating Crystal Detector for the Studies of Low Energy Neutrino Interactions
Scintillating crystal detector may offer some potential advantages in the
low-energy, low-background experiments. A 500 kg CsI(Tl) detector to be placed
near the core of Nuclear Power Station II in Taiwan is being constructed for
the studies of electron-neutrino scatterings and other keV-MeV range neutrino
interactions. The motivations of this detector approach, the physics to be
addressed, the basic experimental design, and the characteristic performance of
prototype modules are described. The expected background channels and their
experimental handles are discussed.Comment: 34 pages, 11 figures, submitted to Nucl. Instrum. Method
High Altitude test of RPCs for the ARGO-YBJ experiment
A 50 m**2 RPC carpet was operated at the YangBaJing Cosmic Ray Laboratory
(Tibet) located 4300 m a.s.l. The performance of RPCs in detecting Extensive
Air Showers was studied. Efficiency and time resolution measurements at the
pressure and temperature conditions typical of high mountain laboratories, are
reported.Comment: 16 pages, 10 figures, submitted to Nucl. Instr. Met
Partial Wave Analysis of
BES data on are presented. The
contribution peaks strongly near threshold. It is fitted with a
broad resonance with mass MeV, width MeV. A broad resonance peaking at 2020 MeV is also required
with width MeV. There is further evidence for a component
peaking at 2.55 GeV. The non- contribution is close to phase
space; it peaks at 2.6 GeV and is very different from .Comment: 15 pages, 6 figures, 1 table, Submitted to PL
A Measurement of Psi(2S) Resonance Parameters
Cross sections for e+e- to hadons, pi+pi- J/Psi, and mu+mu- have been
measured in the vicinity of the Psi(2S) resonance using the BESII detector
operated at the BEPC. The Psi(2S) total width; partial widths to hadrons,
pi+pi- J/Psi, muons; and corresponding branching fractions have been determined
to be Gamma(total)= (264+-27) keV; Gamma(hadron)= (258+-26) keV, Gamma(mu)=
(2.44+-0.21) keV, and Gamma(pi+pi- J/Psi)= (85+-8.7) keV; and Br(hadron)=
(97.79+-0.15)%, Br(pi+pi- J/Psi)= (32+-1.4)%, Br(mu)= (0.93+-0.08)%,
respectively.Comment: 8 pages, 6 figure
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