Standard Model Higgs boson mass from inflation

We analyse one-loop radiative corrections to the inflationary potential in the theory, where inflation is driven by the Standard Model Higgs field. We show that inflation is possible provided the Higgs mass m_H lies in the interval m_min<m_H<m_max, where m_min=[136.7+(m_t-171.2)*1.95]GeV, m_max=[184.5+(m_t-171.2)*0.5]GeV and m_t is the mass of the top quark. Moreover, the predictions of the spectral index of scalar fluctuations and of the tensor-to-scalar ratio practically do not depend on the Higgs mass within the admitted region and are equal to n_s=0.97 and r=0.0034 correspondingly.Comment: 5 pages, 3 figures. Journal version+misprint fixed and added reference to the two-loop analysis paper for convenienc

Heisenberg-limited eavesdropping on the continuous-variable quantum cryptographic protocol with no basis switching is impossible

The Gaussian quantum key distribution protocol based on coherent states and heterodyne detection [Phys. Rev. Lett. 93, 170504 (2004)] has the advantage that no active random basis switching is needed on the receiver's side. Its security is, however, not very satisfyingly understood today because the bounds on the secret key rate that have been derived from Heisenberg relations are not attained by any known scheme. Here, we address the problem of the optimal Gaussian individual attack against this protocol, and derive tight upper bounds on the information accessible to an eavesdropper. The optical scheme achieving this bound is also exhibited, which concludes the security analysis of this protocol.Comment: 10 pages, 6 figure

Gluon distributions in nucleons and pions at a low resolution scale

In this paper we study the gluon distribution functions in nucleons and pions at a low resolution $Q^2$ scale. This is an important issue since parton densities at low $Q^2$ have always been taken as an external input which is adjusted through DGLAP evolution to fit the experimental data at higher scales. Here, in the framework of a model recently developed, it is shown that the hypothetical cloud of {\it neutral} pions surrounding nucleons and pions appears to be responsible for the characteristic valence-like gluon distributions needed at the inital low scale. As an additional result, we get the remarkable prediction that neutral and charged pions have different intrinsic sea flavor contents.Comment: final version to appear in Phys. Rev. D. Discussion on several points enlarge

Bargmann-Michel-Telegdi equation and one-particle relativistic approach

A reexamination of the semiclassical approach of the relativistic electron indicates a possible variation of its helicity for electric and magnetic static fields applied along its global motion due to zitterbewegung effects, proportional to the anomalous part of the magnetic moment.Comment: 10 pages, LATEX2E, uses amsb

Introduction to 2D and 3D tomographic methods based on straight line propagation: X-ray, emission and ultrasonic tomography

This paper presents the basic principles of computerized tomography (CT), and its evolution towards three dimensional (3D ) imaging . Since the modelisation of CT reconstruction relies on the Radon transform, its definition and major properties are firs t recalled. After a brief summary on conventional 2D methods, we present the imaging principles for two modalities appropriate d to this modelisation : X-Ray and emission tomography. We describe the evolution of the instrumentation for these two techniques , and emphasize the approximations introduced by a modelisation using the Radon transform taking into account the physics o f the problem . We also describe the principles of ultrasonic tomography systems, and their major differences with the two previou s technics . At last, we formulate the general problematic of 3D image reconstruction from 2D projections . We consider four classe s of reconstruction methods corresponding to the classification chosen for the synthetic presentation of methods, accompanying thi s paper.Cet article présente les principes de base de la tomographie assistée par ordinateur, ainsi que son évolution vers le tridimen - sionnel (3D) . La modélisation mathématique du problème de reconstruction tomographique s'appuie sur la transformatio n de Radon dont la définition et quelques propriétés sont rappelées . Après un bref résumé sur les méthodes conventionnelle s 2D, nous présentons les principes physiques pour deux modalités bien appropriées à cette modélisation : la tomographie de transmission par rayons X et la tomographie d'émission par rayons ,y . Nous nous attachons à décrire l'évolution de l'instru - mentation dans ces deux techniques, ainsi que les approximations introduites par une modélisation de type Transformée de Radon par rapport à la physique du problème . Nous décrivons également les principes des systèmes de tomographie ultrasonore, et leurs différences majeures par rapport aux deux techniques précédentes . Enfin, nous reprenons la problématiqu e générale des méthodes de reconstruction 3D à partir de projections 2D . Nous faisons apparaître quatre classes correspondan t au découpage choisi pour la présentation des fiches techniques accompagnant cet article