De Beaux Groupes

In this short paper, we will provide a characterisation of interpretable groups in a beautiful pair (K, E) of algebraically closed fields : every interpretable group is, up to isogeny, the extension of the subgroup of E-rational points of an algebraic group by an interpretable group which is the quotient of an algebraic group by the E-rational points of an algebraic subgroup.---Dans une belle paire (K;E) de corps alg\'ebriquement clos, un groupe d\'efinissable se projette, \`a isog\'enie pr\`es, sur les points E-rationnels d'un groupe alg\'ebrique ayant pour noyau un groupe alg\'ebrique. Un groupe interpr\'etable est, \`a isog\'enie pr\`es, l'extension des points E-rationnels d'un groupe alg\'ebrique par un groupe interpr\'etable, qui est lui le quotient d'un groupe alg\'ebrique par les points E-rationnels d'un sous-groupe alg\'ebrique.Comment: in Frenc

On Variants of CM-triviality

We introduce a generalization of CM-triviality relative to a fixed invariant collection of partial types, in analogy to the Canonical Base Property defined by Pillay, Ziegler and Chatzidakis which generalizes one-basedness. We show that, under this condition, a stable field is internal to the family, and a group of finite Lascar rank has a normal nilpotent subgroup such that the quotient is almost internal to the family

Sur les collapses de corps différentiels colorés en caractéristique nulle décrits par Poizat à l'aide des amalgames à la Hrushovski.

Nous collapsons le corps diff´erentiel rouge de Poizat en des corps diff´erentiellement clos de rang de Morley ! · 2, chacun muni d'un sous-groupe additif d´efinissable de rang !. En utilisant la d´eriv´ee logarithmique, on obtient un corps vert de rang ! · 2 avec un sous-groupe multiplicatif d´efinissable divisible contenant le corps des constantes, qui reste d´efinissable dans le r´eduit `a la structure de corps vert

Un Crit{\`E}Re Simple

In this short note, we mimic the proof of the simplicity of the theory ACFA of generic difference fields in order to provide a criterion, valid for certain theories of pure fields and fields equipped with operators, which shows that a complete theory is simple whenever its definable and algebraic closures are controlled by an underlying stable theory.Comment: in Frenc

Exotic and excited-state radiative transitions in charmonium from lattice QCD

We compute, for the first time using lattice QCD methods, radiative transition rates involving excited charmonium states, states of high spin and exotics. Utilizing a large basis of interpolating fields we are able to project out various excited state contributions to three-point correlators computed on quenched anisotropic lattices. In the first lattice QCD calculation of the exotic 1-+ eta_c1 radiative decay, we find a large partial width Gamma(eta_c1 -> J/psi gamma) ~ 100 keV. We find clear signals for electric dipole and magnetic quadrupole transition form factors in chi_c2 -> J/psi gamma, calculated for the first time in this framework, and study transitions involving excited psi and chi_c1,2 states. We calculate hindered magnetic dipole transition widths without the sensitivity to assumptions made in model studies and find statistically significant signals, including a non-exotic vector hybrid candidate Y_hyb? -> eta_c gamma. As well as comparison to experimental data, we discuss in some detail the phenomenology suggested by our results and the extent to which it mirrors that of quark potential models and make suggestions for the interpretation of our results involving exotic quantum numbered states

Sous-groupes additifs de rangs dénombrables dans un corps séparablement clos

International audiencePour tout entier n, on construit des sous-groupes, infiniment définissables de rang de Lascar !n, du groupe additif d'un corps séparablement clos

Simplicity of the automorphism group of fields with operators

We adapt a proof of Lascar in order to show the simplicity of the group of automorphisms fixing pointwise all non-generic elements for a class of uncountable models of suitable theories of fields with operators