216 research outputs found
Effective Hamiltonian Approach to Hyperon Beta Decay with Final-State Baryon Polarization
Using an effective Hamiltonian approach, we obtain expressions for hyperon
beta decay final-state baryon polarization. Terms through second order in the
energy release are retained. The resulting approximate expressions are much
simpler and more compact than the exact expressions, and they agree closely
with them.Comment: 1 Figure Will appear in Phys Rev D 60 Article 117505 (Dec 1, 1999
Two neutrino positron double beta decay of Cd for transition
The two neutrino positron double beta decay of Cd for 0
0 transition has been studied in the Hartree-Fock-Bogoliubov model in
conjunction with the summation method. In the first step, the reliability of
the intrinsic wave functions of Cd and Pd nuclei has been
tested by comparing the theoretically calculated results for yrast spectra,
reduced : transition probabilities, quadrupole moments
and gyromagnetic factors with the available experimental
data. In the second step, the nuclear transition matrix element and
the half-life for 0 0 transition have been
calculated with these wave functions. Moreover, we have studied the effect of
deformation on nuclear transition matrix element MComment: 20 page
A hyaluronidase activity of the sperm plasma membrane protein PH-20 enables sperm to penetrate the cumulus cell layer surrounding the egg.
What can we learn from neutrinoless double beta decay experiments?
We assess how well next generation neutrinoless double beta decay and normal
neutrino beta decay experiments can answer four fundamental questions. 1) If
neutrinoless double beta decay searches do not detect a signal, and if the
spectrum is known to be inverted hierarchy, can we conclude that neutrinos are
Dirac particles? 2) If neutrinoless double beta decay searches are negative and
a next generation ordinary beta decay experiment detects the neutrino mass
scale, can we conclude that neutrinos are Dirac particles? 3) If neutrinoless
double beta decay is observed with a large neutrino mass element, what is the
total mass in neutrinos? 4) If neutrinoless double beta decay is observed but
next generation beta decay searches for a neutrino mass only set a mass upper
limit, can we establish whether the mass hierarchy is normal or inverted? We
base our answers on the expected performance of next generation neutrinoless
double beta decay experiments and on simulations of the accuracy of
calculations of nuclear matrix elements.Comment: Added reference
Capture rate and neutron helicity asymmetry for ordinary muon capture on hydrogen
Applying heavy-baryon chiral perturbation theory to ordinary muon capture
(OMC) on a proton, we calculate the capture rate and neutron helicity asymmetry
up to next-to-next-to-leading order. For the singlet hyperfine state, we obtain
the capture rate Gamma_0 = 695 sec^{-1} while, for the triplet hyperfine state,
we obtain the capture rate Gamma_1 = 11.9 sec^{-1} and the neutron asymmetry
alpha_1 = 0.93. If the existing formalism is used to relate these atomic
capture rates to Gamma_{liq}, the OMC rate in liquid hydrogen, then Gamma_{liq}
corresponding to our improved values of Gamma_0 and Gamma_1 is found to be
significantly larger than the experimental value, primarily due to the updated
larger value of g_A. We argue that this apparent difficulity may be correlated
to the specious anomaly recently reported for mu^- + p to n + nu_mu + gamma,
and we suggest a possibility to remove these two "problems" simply and
simultaneously by reexamining the molecular physics input that underlies the
conventional analysis of Gamma_{liq}.Comment: 14 pages, 1 figur
CUORE: A Cryogenic Underground Observatory for Rare Events
CUORE is a proposed tightly packed array of 1000 TeO2 bolometers, each being
a cube 5 cm on a side with a mass of 760 g. The array consists of 25 vertical
towers, arranged in a square of 5 towers by 5 towers, each containing 10 layers
of 4 crystals. The design of the detector is optimized for ultralow-background
searches: for neutrinoless double beta decay of 130Te (33.8% abundance), cold
dark matter, solar axions, and rare nuclear decays. A preliminary experiment
involving 20 crystals 3x3x6 cm3 of 340 g has been completed, and a single CUORE
tower is being constructed as a smaller scale experiment called CUORICINO. The
expected performance and sensitivity, based on Monte Carlo simulations and
extrapolations of present results, are reported.Comment: 39 pages, 12 figures, submitted to NI
Views of the Chiral Magnetic Effect
My personal views of the Chiral Magnetic Effect are presented, which starts
with a story about how we came up with the electric-current formula and
continues to unsettled subtleties in the formula. There are desirable features
in the formula of the Chiral Magnetic Effect but some considerations would lead
us to even more questions than elucidations. The interpretation of the produced
current is indeed very non-trivial and it involves a lot of confusions that
have not been resolved.Comment: 19 pages, no figure; typos corrected, references significantly
updated, to appear in Lect. Notes Phys. "Strongly interacting matter in
magnetic fields" (Springer), edited by D. Kharzeev, K. Landsteiner, A.
Schmitt, H.-U. Ye
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