4,636 research outputs found
Texture of fermion mass matrices in partially unified theories
We investigate the texture of fermion mass matrices in theories with partial
unification (for example ) at a scale
GeV. Starting with the low energy values of the masses and the
mixing angles, we find only two viable textures with atmost four texture zeros.
One of these corresponds to a somewhat modified Fritzsch textures. A
theoretical derivataion of these textures leads to new interesting relations
among the masses and the mixing angles.Comment: 10 pages(Latex
CP-Violation For Including Long-Distance Effects
We consider the CP violating effect for process, including
both short and long distance effects. We obtain the CP asymmetry parameter and
present its variation over the dilepton mass.Comment: 9 pages, Latex file, one figure include
CP Violation in a Multi-Higgs Doublet Model
We study CP violation in a multi-Higgs doublet model based on a horizontal symmetry. We consider two mechanisms for CP violation in this
model: a) CP violation due to complex Yukawa couplings; and b) CP violation due
to scalar-pseudoscalar mixings. We find that the predictions for
, CP violation in B decays and the electric dipole moments
of neutron and electron are different between these two mechanisms. These
predictions are also dramatically different from the minimal Standard Model
predictions.Comment: 17 pages + one figure, Revtex. Talk presented by Deshpande at the
Conference WHEPP-3, December 199
Anomalous Neutrino Reactions at HERA
We study the sensitivity of HERA to new physics using the helicity suppressed
reaction , where the final neutrino can be a standard
model one or a heavy neutrino. The approach is model independent and is based
on an effective lagrangian parametrization. It is shown that HERA will put
significant bounds on the scale of new physics, though, in general, these are
more modest than previously thought. If deviations from the standard model are
observed in the above processes, future colliders such as the SSC and LHC will
be able to directly probe the physics responsible for these discrepancies}Comment: 11 Pages + 2 figures is TOPDRAWER (included at the end or available
by mail). Report UCRHEP-T113 (requires the macropackage PHYZZX). A line in
the TeX file requesting an input file has been removed, it caused problem
Semi-Inclusive B\to K(K^*) X Decays with Initial Bound State Effects
The effects of initial quark bound state for the semi-inclusive decays
are studied using light cone expansion and heavy quark
effective theory methods. We find that the initial bound state effects on the
branching ratios and CP asymmetries are small. In the light cone expansion
approach, the CP-averaged branching ratios are increased by about 2% with
respect to the free -quark decay. For , the
CP-averaged branching ratios are sensitive to the phase and the CP
asymmetry can be as large as 7% (14%), whereas for the CP-averaged branching ratios are not sensitive to and
the CP asymmetries are small (). The CP-averaged branching ratios are
predicted to be in the ranges [] for and [] for , depending on the value of the CP violating phase . In
the heavy quark effective theory approach, we find that the branching ratios
are decreased by about 10% and the CP asymmetries are not affected. These
predictions can be tested in the near future.Comment: 29 pages, 12 ps figure
Hadronic decays of B involving a tensor meson through a transition
We re-analyze hadronic decays of B mesons to a pseudoscalar (P) and a tensor
meson (T), or a vector meson (V) and a tensor meson, through a
transition. We discuss possible large uncertainties to branching ratios (BR's)
of the relevant modes, mainly arising from uncertainties to the hadronic form
factors for the transition. The BR's and CP asymmetries for and VT decays are then calculated by using the form factors given in the
ISGW2 model (the improved version of the original Isgur-Scora-Grinstein-Wise
(ISGW) model). We find that the estimated BR's of many modes are increased by
an order of magnitude, compared to the previous results calculated within the
ISGW model.Comment: 22 pages, LaTex; minor clarifications included; to appear in Phys.
Rev.
Does tiny-scale atomic structure exist in the interstellar medium ?
We report on preliminary results from the recent multi-epoch neutral hydrogen
absorption measurements toward three pulsars, B0823+26, B1133+16 and B2016+28,
using the Arecibo telescope. We do not find significant variations in optical
depth profiles over periods of 0.3 and 9--10 yr, or on spatial scales of 10--20
and 70--85 AU. The large number of non detections of the tiny scale atomic
structure suggests that the AU-sized structure is not ubiquitous in the
interstellar medium and could be quite a rare phenomenon.Comment: Accepted by ApJ Letters, 5 pages, 2 figure
Analysis of Charge Asymmetry in Rare Dilepton Decays
We analyze forward-backward charge asymmetry of the lepton production in rare
decays and , including
vector-resonance effects. Certain regions of phase space, in which the
asymmetry is sensitive to individual short-distance coefficients, are pointed
out. In particular, we suggest a method to test the coupling of the leptonic
axial vector current to the left-handed quark current experimentally.Comment: 27 pages, 4 figures available up to requiremen
Chemical passivation of unstable FeO - a Mossbauer study
Highly unstable FeO is chemically passivated by incorporating Cr3+ ions by solid solution technique and forming FexO:Cr3+ single phase material. XRD, chemical analysis and Mossbauer spectroscopy are used for the characterization of the freshly prepared as well as samples aged in the desiccator for nearly three months. Optimum concentration range - 0.25 to 0.75 mole% - of Cr2O3 has been found to be necessary for stabilizing FexO:Cr3+. x is determined by chemical analysis. Mossbauer and XRD studies have confirmed the chemical passivation of unstable FeO
Sum Rules and Moments of the Nucleon Spin Structure Functions
The nucleon has been used as a laboratory to investigate its own spin
structure and Quantum Chromodynamics. New experimental data on nucleon spin
structure at low to intermediate momentum transfers combined with existing high
momentum transfer data offer a comprehensive picture of the transition region
from the {\it confinement} regime of the theory to its {\it asymptotic freedom}
regime. Insight for some aspects of the theory is gained by exploring lower
moments of spin structure functions and their corresponding sum rules (i.e. the
Gerasimov-Drell-Hearn, Bjorken and Burkhardt-Cottingham). These moments are
expressed in terms of an operator product expansion using quark and gluon
degrees of freedom at moderately large momentum transfers. The sum rules are
verified to a good accuracy assuming that no singular behavior of the structure
functions is present at very high excitation energies. The higher twist
contributions have been examined through the moments evolution as the moments
evolution as the momentum transfer varies from higher to lower values.
Furthermore, QCD-inspired low-energy effective theories, which explicitly
include chiral symmetry breaking, are tested at low momentum transfers. The
validity of these theories is further examined as the momentum transfer
increases to moderate values. It is found that chiral perturbation calculations
agree reasonably well with the first moment of the spin structure function
at momentum transfer of 0.1 GeV but fail to reproduce the neutron
data in the case of the generalized polarizability .Comment: 21 pages, 4 figures, review for Modern Physics Letters A. Minor
modifications in text and improved quality for one figure. Corrected mistakes
in section
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