In this note, we study the scattering amplitude for the Schrödinger equation with constant magnetic field. We consider the case where the strengh of the magnetic field goes to infinity and we discuss the competition between the magnetic and the electrostatic effects.
We obtain some microlocal estimates of the resonant states associated to a resonance of an -differential operator. More precisely, we show that the normalized resonant states are outside the set of trapped trajectories and are in the incoming area of the phase space. As an application, we show that the residue of the scattering amplitude of a Schrödinger operator is small in some directions under an estimate of the norm of the spectral projector. Finally we prove such bound...
1. Introduction. Our aim is to test numerically the new method of interpolation determinants (cf. [2], [6]) in the context of linear forms in two logarithms. In the recent years, M. Mignotte and M. Waldschmidt have used Schneider's construction in a series of papers [3]-[5] to get lower bounds for such a linear form with rational integer coefficients. They got relatively precise results with a numerical constant around a few hundreds. Here we take up Schneider's method again in the framework...
In this note we describe recent results on semiclassical random walk associated to a probability density which may also concentrate as the semiclassical parameter goes to zero. The main result gives a spectral asymptotics of the close to eigenvalues. This problem was studied in [] and relies on a general factorization result for pseudo-differential operators. In this note we just sketch the proof of this second theorem. At the end of the note, using the factorization, we give a new proof of the...
Soient une courbe algébrique affine de définie sur , et un point de qui n’est pas algébrique. On démontre l’existence d’une infinité de “bonnes” approximations de par des points algébriques de de degré et taille bornés, les majorants du degré et de la taille étant choisis à l’intérieur de suites satisfaisant certaines conditions de croissance modérée. On établit aussi une minoration du degré de ces bonnes approximations, raffinant ainsi un résultat de Wirsing. Comme corollaire, nous...
Let be a real number and let be a positive integer. We define four exponents of Diophantine approximation, which complement the exponents and defined by Mahler and Koksma. We calculate their six values when and is a real number whose continued fraction expansion coincides with some Sturmian sequence of positive integers, up to the initial terms. In particular, we obtain the exact exponent of approximation to such a continued fraction by quadratic surds.
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