Search results for "LESS"
showing 10 items of 2452 documents
Electromagnetic properties of neutrinos in a medium
1989
We show that, contrary to the situation in the vacuum, a Majorana neutrino can have electric and magnetic dipole moments in a medium. This is because of new contributions, equal for a particle and its antiparticle, that can arise only in a material background. For Dirac neutrinos, these contributions make the magnitudes of the dipole moments of the particle and the antiparticle unequal. We discuss the conditions which give rise to such effects, with particular attention to the role played by the discrete symmetries {ital C}, {ital P}, and {ital T}.
Particle creation by wormholes: A 1 + 1 model
2020
The propagation of a free massless scalar field in a [Formula: see text]-dimensional Minkowski space modeling, a wormhole is considered. The wormhole model consists on two timelike trajectories, which represent the entrance and the exit of the wormhole, connected via some transfer function that specifies how incoming modes that reach the entrance are transferred to the exit. We find that particles and energy fluxes are generically produced except for transfer functions that represent global conformal transformations. We consider several examples involving exit trajectories which are asymptotically inertial, asymptotically null, and also involving a faster-than-light motion to illustrate th…
Some Properties of Massless Particles in Arbitrary Dimensions
1998
Various properties of two kinds of massless representations of the n-conformal (or (n+1)-De Sitter) group [Formula: see text] are investigated for n≥2. It is found that, for space-time dimensions n≥3, the situation is quite similar to the one of the n=4 case for Sn-massless representations of the n-De Sitter group [Formula: see text]. These representations are the restrictions of the singletons of [Formula: see text]. The main difference is that they are not contained in the tensor product of two UIRs with the same sign of energy when n>4, whereas it is the case for another kind of massless representations. Finally some examples of Gupta–Bleuler triplets are given for arbitrary spin and…
Random polarisations of the dipoles
2012
We extend the dipole formalism for massless and massive partons to random polarisations of the external partons. The dipole formalism was originally formulated for spin-summed matrix elements and later extended to individual helicity eigenstates. For efficiency reasons one wants to replace the spin sum by a smooth integration over additional variables. This requires the extension of the dipole formalism to random polarisations. In this paper we derive the modified subtraction terms. We only modify the real subtraction terms, the integrated subtraction terms do not require any modifications.
Leptonic CP violation with massless neutrinos
1989
Abstract Leptonic CP violation may arise in the SU(2) ⊗ U(1) theory even if the neutrinos are strictly massless and, as a result, it is potentially large. Theoretical scenarios include isosinglet neutral heavy leptons which are present in many extensions of the standard electroweak theory such as superstring inspired models. We discuss in detail the nature of this CP violation and show that it can occur in a two-generation model. Possible effects are briefly discussed.
LeptonicCPasymmetries in flavor-changingH0decays
1993
Leptonic flavor-changing ${H}^{0}$ decays with branching ratios of the order of ${10}^{\ensuremath{-}5}$-${10}^{\ensuremath{-}6}$ may constitute an interesting framework when looking for large $\mathrm{CP}$-violating effects. We show that leptonic $\mathrm{CP}$ asymmetries of an intermediate ${H}^{0}$ boson can be fairly large in natural scenarios of the minimal standard model with right-handed neutrinos, at a level that may be probed at future ${H}^{0}$ factories.
Virtual compton scattering under π0 threshold at Q2=0.33 GeV2. Preliminary results
1999
We have measured the absolute unpolarized cross sections for photon electro-production off the proton ep → epγ with the Three-Spectrometer-Setup at MAMI at a momentum transfer q=600 MeV/c and a virtual photon polarization ɛ=0.62. The momentum q ′ of the outgoing real photon range from 33 to 111 MeV/c. We extracted two combinations of the recently introduced generalized polarizabilities [1,2].
O(αs)corrections to the correlator of finite mass baryon currents
2000
We present analytical next-to-leading order results for the correlator of baryonic currents at the three-loop level with one finite mass quark. We obtain the massless and the HQET limit of the correlator from the general formula as particular cases. We also give explicit expressions for the moments of the spectral density.
Neutrinoless double beta decays of 106Cd revisited
2011
Abstract Neutrinoless double beta ( 0 ν 2 β ) decays of 106 Cd are studied for the transitions to the ground state, 0 gs + , and 0 + excited states in 106 Pd by using realistic many-body wave functions calculated in the framework of the quasiparticle random-phase approximation and its extensions. Effective, G-matrix-based nuclear forces are used in large single-particle model spaces. Both the β + β + and β + EC channels of the 0 ν 2 β decay are discussed and half-lives are computed. Particular attention is devoted to the study of the detectability of the resonant neutrinoless double electron capture ( R 0 ν ECEC ) process in 106 Cd. The calculations of the present article constitute the thu…
Rateless codes mitigation technique in a turbulent indoor Free Space Optics link
2014
Free Space Optics (FSO) links are affected by several impairments and, among them, optical turbulence is the most important factor that can degrade the link quality. Due to the presence of this phenomenon, the signal irradiance detected by the receiver fluctuates, thus causing erasure errors and fading events. In this work, we present an indoor Free Space Optics link, in which several turbulence conditions are generated by using two heating elements. We show that the generated turbulence causes erasure errors and packet losses during the data transmission, and we also compare the statistical distribution of the samples with the theoretical models. Moreover, we demonstrate how the applicatio…