Search for the Standard Model Higgs boson at LEP

The combined results of the search for the Standard Model Higgs boson from the four LEP experiments are given. These results are based on the full data sample collected by ALEPH, DELPHI, L3 and OPAL at centre-of-mass energies up to 209GeV, corresponding to a total integrated luminosity of about 2.5fb-1. A slight excess of events over the background expectation is found at the 2sigma level, originating mainly from the ALEPH 4-jet channel. This excess is compatible with what expected for the production of a SM Higgs boson with a mass of 115.6GeV/c2. A combined 95% confidence level lower limit of 114.1GeV/c2 on the mass of the Standard Model Higgs boson is derived.Comment: 12 pages, 4 figures, La Thuile 2002 proceeding

Is there new physics in the 1999 ALEPH data ?

The first results on searches performed by ALEPH on the 1999 data sample are presented here. They are based on an integrated luminosity of about 54 pb$^-1$ collected at the two centre-of-mass energies of 192 and 196 GeV. Preliminary results on searches for supersymmetric particles and for the neutral Higgs bosons are shown.Comment: 3 page

What caused the GeV flare of PSR B1259-63 ?

PSR B1259-63 is a gamma-ray binary system composed of a high spindown pulsar and a massive star. Non-thermal emission up to TeV energies is observed near periastron passage, attributed to emission from high energy e+e- pairs accelerated at the shock with the circumstellar material from the companion star, resulting in a small-scale pulsar wind nebula. Weak gamma-ray emission was detected by the Fermi/LAT at the last periastron passage, unexpectedly followed 30 days later by a strong flare, limited to the GeV band, during which the luminosity nearly reached the spindown power of the pulsar. The origin of this GeV flare remains mysterious. We investigate whether the flare could have been caused by pairs, located in the vicinity of the pulsar, up-scattering X-ray photons from the surrounding pulsar wind nebula rather than UV stellar photons, as usually assumed. Such a model is suggested by the geometry of the interaction region at the time of the flare. We compute the gamma-ray lightcurve for this scenario, based on a simplified description of the interaction region, and compare it to the observations. The GeV lightcurve peaks well after periastron with this geometry. The pairs are inferred to have a Lorentz factor ~500. They also produce an MeV flare with a luminosity ~1e34 erg/s prior to periastron passage. A significant drawback is the very high energy density of target photons required for efficient GeV emission. We propose to associate the GeV-emitting pairs with the Maxwellian expected at shock locations corresponding to high pulsar latitudes, while the rest of the non-thermal emission arises from pairs accelerated in the equatorial region of the pulsar wind termination shock.Comment: 6 pages, 3 figures, accepted for publication in A&

Beam-Material Interaction

Th is paper is motivated by the growing importance of better understanding of the phenomena and consequences of high- intensity energetic particle beam interactions with accelerator, generic target , and detector components. It reviews the principal physical processes of fast-particle interactions with matter, effects in materials under irradiation, materials response, related to component lifetime and performance, simulation techniques, and methods of mitigating the impact of radiation on the components and envir onment in challenging current and future applicationComment: 28 pages, contribution to the 2014 Joint International Accelerator School: Beam Loss and Accelerator Protection, Newport Beach, CA, USA , 5-14 Nov 201

k-Fractional trigonometric functions

Based on the k-Mittag-Lefler function and the k-α-Exponential Function we introduce families of functions that allows us define new fractional trigonometric functions that contain the classical trigonometric functions as particular case for some convenient election of parameters. We study some elementary properties and obtain the Laplace transform of some elements of the families.Fil: Cerutti, Ruben Alejandro. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas Naturales y Agrimensura; ArgentinaFil: Luque, Luciano Leonardo. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas Naturales y Agrimensura; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

High-energy radiation from the relativistic jet of Cygnus X-3

Cygnus X-3 is an accreting high-mass X-ray binary composed of a Wolf-Rayet star and an unknown compact object, possibly a black hole. The gamma-ray space telescope Fermi found definitive evidence that high-energy emission is produced in this system. We propose a scenario to explain the GeV gamma-ray emission in Cygnus X-3. In this model, energetic electron-positron pairs are accelerated at a specific location in the relativistic jet, possibly related to a recollimation shock, and upscatter the stellar photons to high energies. The comparison with Fermi observations shows that the jet should be inclined close to the line of sight and pairs should not be located within the system. Energetically speaking, a massive compact object is favored. We report also on our investigations of the gamma-ray absorption of GeV photons with the radiation emitted by a standard accretion disk in Cygnus X-3. This study shows that the gamma-ray source should not lie too close to the compact object.Comment: 4 pages, 3 figures, Proceedings of the SF2A conference held in Marseille, 21-24 June 201

Modeling high-energy pulsar lightcurves from first principles

Current models of gamma-ray lightcurves in pulsars suffer from large uncertainties on the precise location of particle acceleration and radiation. Here, we present an attempt to alleviate these difficulties by solving for the electromagnetic structure of the oblique magnetosphere, particle acceleration, and the emission of radiation self-consistently, using 3D spherical particle-in-cell simulations. We find that the low-energy radiation is synchro-curvature radiation from the polar-cap regions within the light cylinder. In contrast, the high-energy emission is synchrotron radiation that originates exclusively from the Y-point and the equatorial current sheet where relativistic magnetic reconnection accelerates particles. In most cases, synthetic high-energy lightcurves contain two peaks that form when the current sheet sweeps across the observer's line of sight. We find clear evidence of caustics in the emission pattern from the current sheet. High-obliquity solutions can present up to two additional secondary peaks from energetic particles in the wind region accelerated by the reconnection-induced flow near the current sheet. The high-energy radiative efficiency depends sensitively on the viewing angle, and decreases with increasing pulsar inclination. The high-energy emission is concentrated in the equatorial regions where most of the pulsar spindown is released and dissipated. These results have important implications for the interpretation of gamma-ray pulsar data.Comment: 14 pages, 11 figures, Accepted for publication in MNRA