993 research outputs found
H^+ -> W^+ l_i^- l_j^+$ decay in the two Higgs doublet model
We study the lepton flavor violating H^+ -> W^+ l_i^- l_j^+ and the lepton
flavor conserving $H^+ -> W^+ l_i^- l_i^+ (l_i=\tau, l_j=\mu) decays in the
general 2HDM, so called model III. We estimate the decay width \Gamma for LFV
(LFC) at the order of the magnitude of (10^{-11}-10^{-5}) GeV
((10^{-9}-10^{-4}) GeV), for 200 GeV\leq m_{H^\pm}\leq 400
GeV, and the intermediate values of the coupling
\bar{\xi}^{E}_{N,\tau \mu}\sim 5 GeV (\bar{\xi}^{E}_{N,\tau
\tau}\sim 30 GeV). We observe that the experimental result of the process
under consideration can give comprehensive information about the physics beyond
the standard model and the existing free parameters.Comment: 8 pages, 7 Figure
Damping of Tensor Modes in Cosmology
An analytic formula is given for the traceless transverse part of the
anisotropic stress tensor due to free streaming neutrinos, and used to derive
an integro-differential equation for the propagation of cosmological
gravitational waves. The solution shows that anisotropic stress reduces the
squared amplitude by 35.6 % for wavelengths that enter the horizon during the
radiation-dominated phase, independent of any cosmological parameters. This
decreases the tensor temperature and polarization correlation functions for
these wavelengths by the same amount. The effect is less for wavelengths that
enter the horizon at later times. At the longest wavelengths the decrease in
the tensor correlation functions due to neutrino free streaming ranges from
10.7% for to 9.0% for . An Appendix gives a
general proof that tensor as well as scalar modes satisfy a conservation law
for perturbations outside the horizon, even when the anisotropic stress tensor
is not negligible.Comment: 14 pages. The original version of this paper has been expanded to
deal with perturbations of any wavelength. While for wavelengths short enough
to enter the horizon during radiation dominance, temperature and polarization
correlations are damped by 35.6%, at the longest wavelengths the damping is
from 9.0% to 11%. An added Appendix gives a general proof that tensor as well
as scalar modes satisfy a conservation law outside the horizon, even during
neutrino decoupling. Some references are also adde
Yang-Mills Solutions on Euclidean Schwarzschild Space
We show that the apparently periodic Charap-Duff Yang-Mills `instantons' in
time-compactified Euclidean Schwarzschild space are actually time independent.
For these solutions, the Yang-Mills potential is constant along the time
direction (no barrier) and therefore, there is no tunneling. We also
demonstrate that the solutions found to date are three dimensional monopoles
and dyons. We conjecture that there are no time-dependent solutions in the
Euclidean Schwarzschild background.Comment: 12 pages, references added, version to appear in PR
Finite gravitational action for higher derivative and stringy gravities
We generalize the local surface counterterm prescription suggested in
Einstein gravity for higher derivative (HD) and Weyl gravities. Explicitly, the
surface counterterm is found for three- and five-dimensional HD gravities. As a
result, the gravitational action for asymptotically AdS spaces is finite and
gravitational energy-momentum tensor is well-defined. The holographic trace
anomaly for d2 and d4 boundary (gauge) QFT dual to above HD gravity is
calculated from gravitational energy-momentum tensor. The calculation of AdS
black hole mass in HD gravity is presented within above prescrition. The
comparison with the standard prescription (using reference spacetime) is done.Comment: LaTeX file, 21 page
Reduction of the Three Dimensional Schrodinger Equation for Multilayered Films
In this paper, we present a method for reducing the three dimensional
Schrodinger equation to study confined metallic states, such as quantum well
states, in a multilayer film geometry. While discussing some approximations
that are employed when dealing with the three dimensionality of the problem, we
derive a one dimensional equation suitable for studying such states using an
envelope function approach. Some applications to the Cu/Co multilayer system
with regard to spin tunneling/rotations and angle resolved photoemission are
discussed.Comment: 14 pages, 1 figur
Enhancing gravitational wave astronomy with galaxy catalogues
Joint gravitational wave (GW) and electromagnetic (EM) observations, as a key
research direction in multi-messenger astronomy, will provide deep insight into
the astrophysics of a vast range of astronomical phenomena. Uncertainties in
the source sky location estimate from gravitational wave observations mean
follow-up observatories must scan large portions of the sky for a potential
companion signal. A general frame of joint GW-EM observations is presented by a
multi-messenger observational triangle. Using a Bayesian approach to
multi-messenger astronomy, we investigate the use of galaxy catalogue and host
galaxy information to reduce the sky region over which follow-up observatories
must scan, as well as study its use for improving the inclination angle
estimates for coalescing binary compact objects. We demonstrate our method
using a simulated neutron stars inspiral signal injected into simulated
Advanced detectors noise and estimate the injected signal sky location and
inclination angle using the Gravitational Wave Galaxy Catalogue. In this case
study, the top three candidates in rank have , and posterior
probability of being the host galaxy, receptively. The standard deviation of
cosine inclination angle (0.001) of the neutron stars binary using
gravitational wave-galaxy information is much smaller than that (0.02) using
only gravitational wave posterior samples.Comment: Proceedings of the Sant Cugat Forum on Astrophysics. 2014 Session on
'Gravitational Wave Astrophysics
STATIC FOUR-DIMENSIONAL ABELIAN BLACK HOLES IN KALUZA-KLEIN THEORY
Static, four-dimensional (4-d) black holes (BH's) in ()-d Kaluza-Klein
(KK) theory with Abelian isometry and diagonal internal metric have at most one
electric () and one magnetic () charges, which can either come from the
same -gauge field (corresponding to BH's in effective 5-d KK theory) or
from different ones (corresponding to BH's with isometry
of an effective 6-d KK theory). In the latter case, explicit non-extreme
solutions have the global space-time of Schwarzschild BH's, finite temperature,
and non-zero entropy. In the extreme (supersymmetric) limit the singularity
becomes null, the temperature saturates the upper bound
, and entropy is zero. A class of KK BH's with
constrained charge configurations, exhibiting a continuous electric-magnetic
duality, are generated by global transformations on the above classes
of the solutions.Comment: 11 pages, 2 Postscript figures. uses RevTeX and psfig.sty (for figs)
paper and figs also at ftp://dept.physics.upenn.edu/pub/Cvetic/UPR-645-
Direct CP violation and the ÎI=1/2 rule in KâÏÏ decay from the standard model
We present a lattice QCD calculation of the ÎI=1/2, KâÏÏ decay amplitude A0 and Ï”âČ, the measure of direct CP violation in KâÏÏ decay, improving our 2015 calculation [1] of these quantities. Both calculations were performed with physical kinematics on a 323Ă64 lattice with an inverse lattice spacing of a-1=1.3784(68)ââGeV. However, the current calculation includes nearly 4 times the statistics and numerous technical improvements allowing us to more reliably isolate the ÏÏ ground state and more accurately relate the lattice operators to those defined in the standard model. We find Re(A0)=2.99(0.32)(0.59)Ă10-7ââGeV and Im(A0)=-6.98(0.62)(1.44)Ă10-11ââGeV, where the errors are statistical and systematic, respectively. The former agrees well with the experimental result Re(A0)=3.3201(18)Ă10-7ââGeV. These results for A0 can be combined with our earlier lattice calculation of A2 [2] to obtain Re(Ï”âČ/Ï”)=21.7(2.6)(6.2)(5.0)Ă10-4, where the third error represents omitted isospin breaking effects, and Re(A0)/Re(A2)=19.9(2.3)(4.4). The first agrees well with the experimental result of Re(Ï”âČ/Ï”)=16.6(2.3)Ă10-4. A comparison of the second with the observed ratio Re(A0)/Re(A2)=22.45(6), demonstrates the standard model origin of this âÎI=1/2 ruleâ enhancement.We present a lattice QCD calculation of the , decay amplitude and , the measure of direct CP-violation in decay, improving our 2015 calculation of these quantities. Both calculations were performed with physical kinematics on a lattice with an inverse lattice spacing of GeV. However, the current calculation includes nearly four times the statistics and numerous technical improvements allowing us to more reliably isolate the ground-state and more accurately relate the lattice operators to those defined in the Standard Model. We find GeV and GeV, where the errors are statistical and systematic, respectively. The former agrees well with the experimental result GeV. These results for can be combined with our earlier lattice calculation of to obtain , where the third error represents omitted isospin breaking effects, and Re/Re. The first agrees well with the experimental result of . A comparison of the second with the observed ratio ReRe, demonstrates the Standard Model origin of this " rule" enhancement
SUSY-QCD decoupling properties in H+ -> t \bar b decay
The SUSY-QCD radiative corrections to the \Gamma (H+ -> t \bar b) partial
decay width are analyzed within the Minimal Supersymmetric Standard Model at
the one-loop level, {\mathcal O}(\alpha_s), and in the decoupling limit. We
present the analytical expressions of these corrections in the large SUSY
masses limit and study the decoupling behaviour of these corrections in various
limiting cases. We find that if the SUSY mass parameters are large and of the
same order, the one loop SUSY-QCD corrections {\it do not decouple}. The
non-decoupling contribution is enhanced by \tan \beta and therefore large
corrections are expected in the large \tan \beta limit. In contrast, we also
find that the SUSY-QCD corrections decouple if the masses of either the squarks
or the gluinos are separately taken large.Comment: LaTeX, 33 pages, 7 figure included. Uses cite.st
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