495 research outputs found
Neutrino mass in GUT constrained supersymmetry with R-parity violation in light of neutrino oscillations
The neutrino masses are generated in grand unified theory (GUT) constrained
supersymmetric model with R-parity violation. The neutrinos acquire masses via
tree-level neutrino-neutralino mixing as well as via one-loop radiative
corrections. The theoretical mass matrix is compared with the phenomenological
one, which is reconstructed by using neutrino oscillation and neutrinoless
double beta decay data. This procedure allows to obtain significantly stronger
constraints on R-parity breaking parameters than those existing in the
literature. The implication of normal and inverted neutrino mass hierarchy on
the sneutrino expectation values, lepton-Higgs bilinear and trilinear R-parity
breaking couplings is also discussed
The pion-pion scattering amplitude. III: Improving the analysis with forward dispersion relations and Roy equations
We complete and improve the fits to experimental scattering
amplitudes, both at low and high energies, that we performed in the previous
papers of this series. We then verify that the corresponding amplitudes satisfy
analyticity requirements, in the form of partial wave analyticity at low
energies, forward dispersion relations (FDR) at all energies, and Roy equations
below threshold; the first by construction, the last two, inside
experimental errors. Then we repeat the fits including as constraints FDR and
Roy equations. The ensuing central values of the various scattering amplitudes
verify very accurately FDR and, especially, Roy equations, and change very
little from what we found by just fitting data, with the exception of the D2
wave phase shift, for which one parameter moves by . These improved
parametrizations therefore provide a reliable representation of pion-pion
amplitudes with which one can test various physical relations. We also present
a list of low energy parameters and other observables. In particular, we find
,
and .Comment: Plain TeX. 29 figures. Version to be published in PRD, with improved
P and F wave
Quantum constraints, Dirac observables and evolution: group averaging versus Schroedinger picture in LQC
A general quantum constraint of the form (realized in particular in Loop Quantum Cosmology models) is
studied. Group Averaging is applied to define the Hilbert space of solutions
and the relational Dirac observables. Two cases are considered. In the first
case, the spectrum of the operator is assumed to be
discrete. The quantum theory defined by the constraint takes the form of a
Schroedinger-like quantum mechanics with a generalized Hamiltonian
. In the second case, the spectrum is absolutely continuous
and some peculiar asymptotic properties of the eigenfunctions are assumed. The
resulting Hilbert space and the dynamics are characterized by a continuous
family of the Schroedinger-like quantum theories. However, the relational
observables mix different members of the family. Our assumptions are motivated
by new Loop Quantum Cosmology models of quantum FRW spacetime. The two cases
considered in the paper correspond to the negative and, respectively, positive
cosmological constant. Our results should be also applicable in many other
general relativistic contexts.Comment: RevTex4, 32 page
Effect of the and channels and interference phenomena in the two-pion and transitions of charmonia and bottomonia
It is shown that the basic shape of dipion and mass spectra
in decays , ,
and in the two-pion transitions of bottomonia states
are explained by an unified mechanism based on the contribution of the
, and coupled channels including their
interference. The role of the individual resonances in making up the
shape of the dipion mass distributions in the charmonia and bottomonia decays
is considered.Comment: 13 pages, 9 figure
Symmetries in nonlinear Bethe-Heitler process
Nonlinear Bethe-Heitler process in a bichromatic laser field is investigated
using strong-field QED formalism. Symmetry properties of angular distributions
of created pairs are analyzed. These properties are showed to be
governed by a behavior of the vector potential characterizing the laser field,
rather than by the respective electric field component.Comment: 4 pages, 4 figure
Effect of the channel and interference phenomena in the two-pion transitions of charmonia and bottomonia
The basic shape of di-pion mass spectra in the two-pion transitions of both
charmonia and bottomonia states is explained by an unified mechanism based on
contributions of the , and coupled channels
including their interference. The role of the individual resonances in
shaping the di-pion mass distributions in the charmonia and bottomonia decays
is considered.Comment: 8 pages, 4 figures, Talk at the XXIII International Baldin Seminar on
High Energy Physics Problems "Relativistic Nuclear Physics \& Quantum
Chromodynamics" (Dubna, Russia, 19--24 September 2016). arXiv admin note:
text overlap with arXiv:1610.0789
Review of Ronnie Littlejohn, Jeffrey Dippmann (eds). Riding the Wind with Liezi: New Perspectives on the Daoist Classic
The effect of isoscalar S-wave multichannel pi pi -> pi pi, K antiK, eta eta scattering is considered in the analysis of decay data of the Upsilon-mesons. We show that when allowing for the final state interaction contribution to the decays Upsilon(mS) -> Upsilon(nS) pi pi (m>n, m=2,3, n=1,2) in our model-independent approach, we can explain the two-pion energetic spectra of these Upsilon transitions including the two-humped shape of the di-pion mass distribution in Upsilon(3S) -> Upsilon(1S) pi pi as the coupled-channel effect. It is shown also that the considered bottomia decay data do not offer new insights into the nature of the f0 mesons, which were not already deduced in our previous analyses of pseudoscalar meson scattering data.The effect of isoscalar S-wave multichannel ππ→ππ,KK¯,ηη scattering is considered in the analysis of decay data of the ϒ-mesons. We show that when allowing for the final state interaction contribution to the decays ϒ(mS)→ϒ(nS)ππ (m>n,m=2,3,n=1,2) in our model-independent approach, we can explain the two-pion energetic spectra of these ϒ transitions including the two-humped shape of the di-pion mass distribution in ϒ(3S)→ϒ(1S)ππ as the coupled-channel effect. It is shown also that the considered bottomia decay data do not offer new insights into the nature of the f0 mesons, which were not already deduced in our previous analyses of pseudoscalar meson scattering data.</p
The interference effects of multi-channel pion-pion scattering contributions to the final states of - and -meson family decays
It is shown that the basic shape of dipion mass distributions in the two-pion
transitions of both charmonia and bottomonia states are explained by an unified
mechanism based on the contribution of the , and
coupled channels including their interference.Comment: 5 pages, 3 figures, talk at the14th International Workshop on Meson
Production, Properties and Interaction (Krakow, Poland, 2nd - 7th June 2016
Riemann-Hilbert technique scattering analysis of metamaterial-based asymmetric 2D open resonators
© P.M. Kamiński et al., published by EDP Sciences, 2017. The scattering properties of metamaterial-based asymmetric two-dimensional open resonators excited by an electric line source are investigated analytically. The resonators are, in general, composed of two infinite and concentric cylindrical layers covered with an infinitely thin, perfect conducting shell that has an infinite axial aperture. The line source is oriented parallel to the cylinder axis. An exact analytical solution of this problem is derived. It is based on the dual-series approach and its transformation to the equivalent Riemann-Hilbert problem. Asymmetric metamaterial-based configurations are found to lead simultaneously to large enhancements of the radiated power and to highly steerable Huygens-like directivity patterns; properties not attainable with the corresponding structurally symmetric resonators. The presented open resonator designs are thus interesting candidates for many scientific and engineering applications where enhanced directional near- and far-field responses, tailored with beam shaping and steering capabilities, are highly desired
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