119117428
Aharonov-Bohm-Casher Problem with a nonminimal Lorentz-violating coupling
The Aharonov-Bohm-Casher problem is examined for a charged particle describing a circular path in presence of a Lorentz-violating background nonminimally coupled to a spinor and a gauge field. It were evaluated the particle eigenenergies, showing that the LV background is able to lift the original degenerescence in the absence of magnetic field and even for a neutral particle. The Aharonov-Casher phase is used to impose an upper bound on the background magnitude. A similar analysis is accomplished in a space endowed with a topological defect, revealing that both the disclination parameter and the LV background are able to modify the particle eigenenergies. We also analyze the particular case where the particle interacts harmonically with the topological defect and the LV background, with similar results.
118609457
Relativistic Landau-Aharonov-Casher quantization based on the Lorentz symmetry violation background
Based on the discussions about the Aharonov-Casher effect in the Lorentz symmetry violation background, we show that the analogue of the relativistic Landau quantization in the Aharonov-Casher setup can be achieved in the Lorentz-symmetry violation background.
119697349
On the spin- 1/2 Aharonov-Bohm problem in conical space: Bound states, scattering and helicity nonconservation
In this work the bound state and scattering problems for a spin-1/2 particle undergone to an Aharonov-Bohm potential in a conical space in the nonrelativistic limit are consider ed. The presence of a �-function singularity, which comes from the Zeeman spin interaction with the magnetic flux tube, is addressed by the self-adjoint extension method. One of the advantages of the present approach is the determination of the self-adjoint extension parameter in terms of physics of the problem. Expressions for the energy bound states, phase-shift and S matrix are determined in terms of the self-adjoint extension parameter, which is explicitly determined in terms of the parameters of the problem. The relation between the bound state and zero modes and the failure of helicity conservation in the scattering problem and its relation with the gyromagnetic ratio g are discussed. Also, as an application, we consider the spin-1/2 AharonovBohm problem in conical space plus a two-dimensional isotropic harmonic oscillator.
118670238
He–McKellar–Wilkens effect and scalar Aharonov–Bohm effect for a neutral particle based on the Lorentz symmetry violation
In this contribution, we discuss the He–McKellar–Wilkens effect and the scalar Aharonov–Bohm effect for neutral particles based on the Lorentz symmetry violation background, by showing that the background of the Lorentz symmetry violation yields Abelian quantum phases for a neutral particle. We also study the non-relativistic bound states for a neutral particle interacting with a Coulomb-like potential based on the Lorentz symmetry violation background given by a fixed vector field parallel to the radial direction.
119322655
Finiteness of the noncommutative supersymmetric Maxwell-Chern-Simons theory
Within the superfield approach, we prove the absence of UV/IR mixing in the three-dimensional noncommutative supersymmetric Maxwell-Chern-Simons theory at any loop order and demonstrate its finiteness in one, three, and higher loop orders.
119686840
On Aharonov–Casher scattering in a CPT-odd Lorentz-violating background
The effects of a Lorentz symmetry-violating background vector on Aharonov?Casher scattering in the nonrelativistic limit are considered. Using the self-adjoint extension method, we find that there is additional scattering for any value of the self-adjoint extension parameter and non-zero energy bound states for negative values of this parameter. Expressions for the energy bound states, phase-shift and scattering matrix are explicitly determined in terms of the self-adjoint extension parameter. The expression obtained for the scattering amplitude reveals that the helicity is not conserved in this scenario.
120355862
Fermi LAT observations of cosmic-ray electrons from 7 GeV to 1 TeV
We present the results of our analysis of cosmic-ray electrons using about 8 x 10(6) electron candidates detected in the first 12 months on-orbit by the Fermi Large Area Telescope. This work extend ...
199660907
Measurement of the $B^0$ - $\bar{B}^0$ mixing, Gamma (Z0 $\to b \bar{b}$) / Gamma (Z0 $\to$ hadrons) and semileptonic branching ratios for $b$ flavored hadrons in hadronic z0 decays
From a sample of about 450 000 hadronicZ 0 decays, measurements of the average\(B^0 - \bar B^0 \) mixing parameter, χ, the branching fraction ofZ 0 bosons into hadrons containing bottom quarks,\({{\Gamma (Z^0 \to b\bar b)} \mathord{\left/ {\vphantom {{\Gamma (Z^0 \to b\bar b)} {\Gamma (Z^0 \to hadrons)}}} \right. \kern-\nulldelimiterspace} {\Gamma (Z^0 \to hadrons)}}\), the average semileptonic branching ratios for such hadrons,B(b→l) andB(b→c→l), and the mean scaled energy of these hadrons, 〈xE〉, are presented. The measurements were obtained using a simultaneous fit to single-lepton and dilepton events collected with the OPAL detector at LEP, including both electrons and muons. The results are 
 
where the errors are statistical and systematic, respectively, in each case. The result forB)b→c→l) excludes decays of the typeb→→l.
1529836
Search for a new gauge boson in π0 decays
Abstract A search was made for a new light gauge boson X which might be produced in π 0 → γ + X decay from neutral pions generated by 450 GeV protons in the CERN SPS neutrino target. The X's would penetrate the downstream shielding and be observed in the NOMAD detector via the Primakoff effect, in the process of X → π 0 conversion in the external Coulomb field of a nucleus. With 1.45×10 18 protons on target, 20 candidate events with energy between 8 and 140 GeV were found from the analysis of neutrino data. This number is in agreement with the expectation of 18.1±2.8 background events from standard neutrino processes. A new 90 % C.L. upper limit on the branching ratio Br ( π 0 → γ + X ) −5 for X masses ranging from 0 to 120 MeV/ c 2 is obtained.
209836258
GeV GAMMA-RAY FLUX UPPER LIMITS FROM CLUSTERS OF GALAXIES
The detection of diffuse radio emission associated with clusters of galaxies indicates populations of relativistic leptons infusing the intracluster medium. Those electrons and positrons are either injected into and accelerated directly in the intracluster medium, or produced as secondary pairs by cosmic-ray ions scattering on ambient protons. Radiation mechanisms involving the energetic leptons together with decay of neutral pions produced by hadronic interactions have the potential to produce abundant GeV photons. Here, we report on the search for GeV emission from clusters of galaxies using data collected by the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (Fermi) from August 2008 to February 2010. Thirty-three galaxy clusters have been selected according to their proximity and high mass, X-ray flux and temperature, and indications of non-thermal activity for this study. We report upper limits on the photon flux in the range 0.2-100 GeV towards a sample of observed clusters (typical values 1-5 x 10^-9 ph cm^-2 s^-1) considering both point-like and spatially resolved models for the high-energy emission, and discuss how these results constrain the characteristics of energetic leptons and hadrons, and magnetic fields in the intracluster medium. The volume-averaged relativistic-hadron-to-thermal energy density ratio is found to be < 5-10% in several clusters.
120875826
Search for massive, unstable photinos that violate R parity
Abstract A search for unstable, massive photinos pair produced in e + e − collisions has been performed using the OPAL detector at LEP. The data sample corresponds to an integrated luminosity of 21 pb −1 collected at center-of-mass energies near the Z 0 resonance. The unstable photino is assumed to decay into τ ± / gn l ( l = e or μ ) final states, thereby violating individual lepton numbers and R parity. This search is inspired by a particular model of supersymmetry which is of interest within the context of solar neutrino experiments because it allows for a large neutrino magnetic moment. The present search excludes a large portion of the parameter space allowed by the model.