Influence of the photonuclear effect on electron-neutrino-induced electromagnetic cascades under the Landau-Pomeranchuk-Migdal regime in standard rock

The observation of earth skimming neutrinos has been proposed as a rather sensitive method to detect ultra-high energy (UHE) cosmic neutrinos. Energetic cosmic neutrinos can interact inside the rock and produce leptons via a charged current interaction. In the case of an incoming electron neutrino undergoing a charged current interaction, the produced UHE electron will induce an underground electromagnetic shower. At high energy (above 7.7 TeV in standard rock), such showers are subject to LPM (Landau, Pomeranchuk and Migdal) suppression of the radiative processes cross sections (bremsstrahlung and pair production). The consequence of this suppression is that showers are elongated. This effect will increase the detection probability of such events allowing deeper showers to emerge with detectable energies. On the other hand, the photonuclear processes which are usually neglected in electromagnetic showers with respect to radiative processes, turn out to become dominant in the LPM regime and will reduce the shower length. In this work, we have performed a complete Monte Carlo study of an underground shower induced by UHE electrons by taking into account both the LPM suppression and the photonuclear interaction. We will discuss the effects of both of these processes on the shower length and on the detectability of such events by ground arrays or fluorescence telescopes. We show that limits on neutrino fluxes that were obtained using simulations that were obviously neglecting photonuclear processes are overoptimistic and should be corrected.Comment: 6 pages, 7 figure

Integrable Supersymmetry Breaking Perturbations of N=1,2 Superconformal Minimal Models

We display a new integrable perturbation for both N=1 and N=2 superconformal minimal models. These perturbations break supersymmetry explicitly. Their existence was expected on the basis of the classification of integrable perturbations of conformal field theories in terms of distinct classical KdV type hierarchies sharing a common second Hamiltonian structure.Comment: 10 pages (harvmac), LAVAL PHY-20-9

Investigating the mass of the intermediate mass black hole candidate HLX-1 with the SLIMBH model

In this paper we present a comprehensive study of the mass of the intermediate mass black hole candidate HLX-1 in the galaxy ESO 243-49. We analyse the continuum X-ray spectra collected by Swift, XMM-Newton, and Chandra with the slim disc model, SLIMBH, and estimate the black hole mass for the full range of inclination (inc = 0{\deg} - 85{\deg}) and spin (a* = 0 - 0.998). The relativistic SLIMBH model is particularly suited to study high luminosity disc spectra as it incorporates the effects of advection, such as the shift of the inner disc edge towards smaller radii and the increasing height of the disc photosphere (including relativistic ray-tracing from its proper location rather than the mid-plane of the disc). We find for increasing values of inclination that a zero spin black hole has a mass range of 6,300 - 50,900 M_sun and a maximally spinning black hole has a mass between 16,900 - 191,700 M_sun. This is consistent with previous estimates and reinforces the idea that HLX-1 contains an intermediate mass black hole.Comment: updated version, published in Astronomy and Astrophysic

Modelling, Detection And Exploitation Of Lexical Functions For Analysis.

Lexical functions (LF) model relations between terms in the lexicon. These relations can be knowledge about the world (Napoleon was an emperor) or knowledge about the language (‘destiny’ is synonym of ‘fate’)

Lexical Functions For Ants Based Semantic Analysis.

Semantic analysis (SA) is a central operation in natural language processing. We can consider it as the resolution of 5 problems: lexical ambiguity, references, prepositional attachments, interpretative paths and lexical functions instanciation

Noise characterization of an Optical Frequency Comb using Offline Cross-Correlation

Using an offline cross-correlation technique, we have analyzed the noise behavior of a new type of optical frequency comb (OFC), which is carrier envelope offset (CEO) free by configuration, due to difference frequency generation. In order to evaluate the instrument's ultimate noise floor, the phase and amplitude noise of a stabilized OFC are measured simultaneously using two analog-to-digital converters. Carrier recovery and phase detection are done by post-processing, eliminating the need for external phase-locked loops and complex calibration techniques. In order to adapt the measurement noise floor and the number of averages used in cross correlation, an adaptive frequency resolution for noise measurement is applied. Phase noise results are in excellent agreement with measurements of the fluctuations of the repetition frequency of the OFC obtained from optical signal