3,748 research outputs found
Giant Goos-H\"anchen shift in Scattering: the role of interfering Localized Plasmon modes
The longitudinal and the transverse beam shifts, namely, the Goos-H\"anchen
(GH) and the Spin-Hall (SH) shifts are usually observed at planar interfaces.
It has recently been shown that the transverse SH shift may also arise due to
scattering of plane waves. Here, we show that analogous in-plane (longitudinal)
shift also exist in scattering of plane waves from micro/nano systems. We study
both the GH and the SH shifts in plasmonic metal nanoparticles/ nanostructures
and dielectric micro-particles employing a unified framework that utilizes the
transverse components of the Poynting vector of the scattered wave. The results
demonstrate that interference of neighboring resonance modes in plasmonic
nanostructures (e.g., electric dipolar and quadrupolar modes in metal spheres)
leads to giant enhancement of GH shift in scattering from such systems. We also
unravel interesting correlations between these shifts with the polarimetry
parameters, diattenuation and retardance.Comment: 4 pages, 3 figure
() spectroscopy using Cornell potential
The mass spectra and decay properties of heavy quarkonia are computed in
nonrelativistic quark-antiquark Cornell potential model. We have employed the
numerical solution of Schr\"odinger equation to obtain their mass spectra using
only four parameters namely quark mass (, ) and confinement strength
(, ). The spin hyperfine, spin-orbit and tensor
components of the one gluon exchange interaction are computed perturbatively to
determine the mass spectra of excited , , and states. Digamma,
digluon and dilepton decays of these mesons are computed using the model
parameters and numerical wave functions. The predicted spectroscopy and decay
properties for quarkonia are found to be consistent with available experimental
observations and results from other theoretical models. We also compute mass
spectra and life time of the meson without additional parameters. The
computed electromagnetic transition widths of heavy quarkonia and mesons
are in tune with available experimental data and other theoretical approaches
Proton decay matrix elements with domain-wall fermions
Hadronic matrix elements of operators relevant to nucleon decay in grand
unified theories are calculated numerically using lattice QCD. In this context,
the domain-wall fermion formulation, combined with non-perturbative
renormalization, is used for the first time. These techniques bring reduction
of a large fraction of the systematic error from the finite lattice spacing.
Our main effort is devoted to a calculation performed in the quenched
approximation, where the direct calculation of the nucleon to pseudoscalar
matrix elements, as well as the indirect estimate of them from the nucleon to
vacuum matrix elements, are performed. First results, using two flavors of
dynamical domain-wall quarks for the nucleon to vacuum matrix elements are also
presented to address the systematic error of quenching, which appears to be
small compared to the other errors. Our results suggest that the representative
value for the low energy constants from the nucleon to vacuum matrix elements
are given as |alpha| simeq |beta| simeq 0.01 GeV^3. For a more reliable
estimate of the physical low energy matrix elements, it is better to use the
relevant form factors calculated in the direct method. The direct method tends
to give smaller value of the form factors, compared to the indirect one, thus
enhancing the proton life-time; indeed for the pi^0 final state the difference
between the two methods is quite appreciable.Comment: 56 pages, 17 figures, a comment and two references added in the
introduction, typo corrected in Eq.1
B-factory Signals for a Warped Extra Dimension
We study predictions for B-physics in a class of models, recently introduced,
with a non-supersymmetric warped extra dimension. In these models few () TeV Kaluza-Klein masses are consistent with electroweak data due to bulk
custodial symmetry. Furthermore, there is an analog of GIM mechanism which is
violated by the heavy top quark (just as in SM) leading to striking signals at
-factories:(i) New Physics (NP) contributions to transitions
are comparable to SM. This implies that, within this NP framework, the success
of SM unitarity triangle fit is a ``coincidence'' Thus, clean extractions of
unitarity angles via e.g. are likely to
be affected, in addition to O(1) deviation from SM prediction in mixing.
(ii) O(1) deviation from SM predictions for in rate as well
as in forward-backward and direct CP asymmetry. (iii) Large mixing-induced CP
asymmetry in radiative B decays, wherein the SM unamibgously predicts very
small asymmetries. Also with KK masses 3 TeV or less, and with anarchic Yukawa
masses, contributions to electric dipole moments of the neutron are roughly 20
times larger than the current experimental bound so that this framework has a
"CP problem".Comment: On further consideration, we found that our framework does have a "CP
problem" in that though contributions to neutron's electric dipole moment
from CKM-like phases vanish at the one-loop level, sizeable contributions are
induced by Majorana-like phases. Last sentence of abstract is changed along
with para #3 and 4 on page
Semileptonic D(s)-meson decays in the light of recent data
Inspired by recent improved measurements of charm semileptonic decays at BESIII, we study a large set of D(Ds)-meson semileptonic decays where the hadron in the final state is one of D0, ρ, ω, η ( η') in the case of D+ decays, and D0, φ, K0, K*(892), η (η') in the case of
Ds decays. The required hadronic form factors are computed in the full kinematical range of momentum transfer by employing the covariant confined quark model developed by us. A detailed comparison of the form factors with those from other approaches is provided. We calculate the decay branching fractions and their ratios, which show good agreement with available experimental data. We also give predictions for the forward-backward asymmetry and the longitudinal and transverse polarizations of the charged lepton in the final state
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