620 research outputs found
Radiative corrections to theta term in the left-right supersymmetric models
We calculate the radiative correction to the theta term in the generic
left-right supersymmetric model due to the Kobayashi-Maskawa source of
CP-violation. We found that the value of is very sensitive to
the relations between vacuum expectation values of bidoublet scalars and . The
minimal value of in the model is found to be of order
for , in agreement with the
experimental constraint without an axion mechanism or fine tuning. In other
regions of the parameter space, the radiatively induced gives
unacceptably large contributions to the electric dipole moment of the neutron.Comment: 6 pages, latex, no figure
Enhancement factor for the electron electric dipole moment in francium and gold atoms
If electrons had an electric dipole moment (EDM) they would induce EDMs of
atoms. The ratio of the atomic EDM to the electron EDM for a particular atom is
called the enhancement factor, R. We calculate the enhancement factor for the
francium and gold atoms, with the results 910 plus/minus 5% for Fr and 260
plus/minus 15% for Au. The large values of these enhancement factors make these
atoms attractive for electron EDM measurements, and hence the search for
time-reversal invariance violation.Comment: 6 pages, no figures, uses RevTex, reference adde
Probing CP Violation with the Deuteron Electric Dipole Moment
We present an analysis of the electric dipole moment (EDM) of the deuteron as
induced by CP-violating operators of dimension 4, 5 and 6 including theta QCD,
the EDMs and color EDMs of quarks, four-quark interactions and the Weinberg
operator. We demonstrate that the precision goal of the EDM Collaboration's
proposal to search for the deuteron EDM, (1-3)\times 10^{-27} e cm, will
provide an improvement in sensitivity to these sources of one-two orders of
magnitude relative to the existing bounds. We consider in detail the level to
which CP-odd phases can be probed within the MSSM.Comment: 5 pages, 4 figures; precision estimates clarified, to appear in Phys.
Rev.
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
Precise Calculation of the Relic Density of Kaluza-Klein Dark Matter in Universal Extra Dimensions
We revisit the calculation of the relic density of the lightest Kaluza-Klein
particle (LKP) in the model of Universal Extra Dimensions. The Kaluza-Klein
(KK) particle spectrum at level one is rather degenerate, and various
coannihilation processes may be relevant. We extend the calculation of
hep-ph/0206071 to include coannihilation processes with all level one KK
particles. In our computation we consider a most general KK particle spectrum,
without any simplifying assumptions. In particular, we do not assume a
completely degenerate KK spectrum and instead retain the dependence on each
individual KK mass. As an application of our results, we calculate the
Kaluza-Klein relic density in the Minimal UED model, turning on coannihilations
with all level one KK particles. We then go beyond the minimal model and
discuss the size of the coannihilation effects separately for each class of
level 1 KK particles. Our results provide the basis for consistent relic
density computations in arbitrarily general models with Universal Extra
Dimenions.Comment: 44 pages, 19 figures, typeset in JHEP styl
Supersymmetry and a rationale for small CP violating phases
We analyse the CP problem in the context of a supersymmetric extension of the
standard model with universal strength of Yukawa couplings. A salient feature
of these models is that the CP phases are constrained to be very small by the
hierarchy of the quark masses, and the pattern of CKM mixing angles. This leads
to a small amount of CP violation from the usual KM mechanism and a significant
contribution from supersymmetry is required. Due to the large generation mixing
in some of the supersymmetric interactions, the electric dipole moments impose
severe constraints on the parameter space, forcing the trilinear couplings to
be factorizable in matrix form. We find that the LL mass insertions give the
dominant gluino contribution to saturate epsilon_K. The chargino contributions
to epsilon'/epsilon are significant and can accommodate the experimental
results. In this framework, the standard model gives a negligible contribution
to the CP asymmetry in B-meson decay, a_{J/\psi K_s}. However, due to
supersymmetric contributions to B_d-\bar{B}_d mixing, the recent large value of
a_{J/\psi K_s} can be accommodated.Comment: 30 pages, 5 figures. Version to appear in Nucl. Phys.
Constrained Supersymmetric Flipped SU(5) GUT Phenomenology
We explore the phenomenology of the minimal supersymmetric flipped SU(5) GUT
model (CFSU(5)), whose soft supersymmetry-breaking (SSB) mass parameters are
constrained to be universal at some input scale, , above the GUT scale,
. We analyze the parameter space of CFSU(5) assuming that the lightest
supersymmetric particle (LSP) provides the cosmological cold dark matter,
paying careful attention to the matching of parameters at the GUT scale. We
first display some specific examples of the evolutions of the SSB parameters
that exhibit some generic features. Specifically, we note that the relationship
between the masses of the lightest neutralino and the lighter stau is sensitive
to , as is the relationship between the neutralino mass and the masses
of the heavier Higgs bosons. For these reasons, prominent features in generic
planes such as coannihilation strips and rapid-annihilation
funnels are also sensitive to , as we illustrate for several cases with
tan(beta)=10 and 55. However, these features do not necessarily disappear at
large , unlike the case in the minimal conventional SU(5) GUT. Our
results are relatively insensitive to neutrino masses.Comment: 23 pages, 8 figures; (v2) added explanations and corrected typos,
version to appear in EPJ
CP violation in a multi-Higgs doublet model with flavor changing neutral current
We study CP violation in a multi-Higgs doublet model based on a horizontal symmetry where CKM phase is not the principal source of CP
violation. 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 Higgs boson mixings. Both mechanisms can explain the
observed CP violation in the neutral Kaon system. due to
neutral Higgs boson exchange is small in both mechanisms, but charged Higgs
boson con- tributions can be as large as for a), and for
b). CP violation in the neutral B system is, however, quite different from the
Minimal Standard
Model. The neutron Electric Dipole Moment can be as large as the present ex-
perimental bound, and can be used to constrain charged Higgs boson masses.
The electron
EDM is one order of magnitude below the experimental bound in case b) and
smaller in case a).Comment: 22 pages, Revtex, OITS-52
Gravitational Coupling and Dynamical Reduction of The Cosmological Constant
We introduce a dynamical model to reduce a large cosmological constant to a
sufficiently small value. The basic ingredient in this model is a distinction
which has been made between the two unit systems used in cosmology and particle
physics. We have used a conformal invariant gravitational model to define a
particular conformal frame in terms of large scale properties of the universe.
It is then argued that the contributions of mass scales in particle physics to
the vacuum energy density should be considered in a different conformal frame.
In this manner, a decaying mechanism is presented in which the conformal factor
appears as a dynamical field and plays a key role to relax a large effective
cosmological constant. Moreover, we argue that this model also provides a
possible explanation for the coincidence problem.Comment: To appear in GR
Standard Model Confronting New Results for epsilon'/epsilon
We analyze the CP violating ratio \epe=epsilon'/epsilon in the Standard Model
in view of the new KTeV results. We review the present status of the most
important non-perturbative parameters B_6, B_8, B_K and of the strange quark
mass m_s. We also briefly discuss the issues of final state interactions and
renormalization scheme dependence. Updating the values of the CKM parameters,
of m_t and Lambda (MSbar) and using Gaussian errors for the experimental input
and flat distributions for the theoretical parameters we find \epe
substantially below the NA31 and KTeV data: \epe= (7.7^{+6.0}_{-3.5}) 10^{-4}
and \epe= (5.2^{+4.6}_{-2.7}) 10^{-4} in the NDR and HV renormalization schemes
respectively. A simple scanning of all input parameters gives on the other hand
1.05 10^{-4} < \epe < 28.8 10^{-4} and 0.26 10^{-4} < \epe < 22.0 10^{-4}
respectively. Analyzing the dependence on various parameters we find that only
for extreme values of B_6, B_8 and m_s and suitable values of CKM parameters
and Lambda(MSbar), the ratio \epe can be made consistent with data. We analyze
the impact of these data on the lower bounds for Im(V_{td}V_{ts}^*), Br(K_L to
pi^0 nu barnu), Br(K_L to pi^0e^+e^-)_{dir} and on tan(beta) in the Two Higgs
Doublet Model II.Comment: main latex-file, 4 figures and related latex files, 47 page
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