Non-extensive resonant reaction rates in astrophysical plasmas

We study two different physical scenarios of thermonuclear reactions in stellar plasmas proceeding through a narrow resonance at low energy or through the low energy wing of a wide resonance at high energy. Correspondingly, we derive two approximate analytical formulae in order to calculate thermonuclear resonant reaction rates inside very coupled and non ideal astrophysical plasmas in which non-extensive effects are likely to arise. Our results are presented as simple first order corrective factors that generalize the well known classical rates obtained in the framework of Maxwell-Boltzmann statistical mechanics. As a possible application of our results, we calculate the dependence of the total corrective factor with respect to the energy at which the resonance is located, in an extremely dense and non ideal carbon plasma.Comment: 5 pages, 1 figur

Propagation of Fast Partons in the Nuclear Medium

The color dipole approach has been applied in the target rest frame to address the issues of transverse momentum broadening and energy loss of a fast quark propagating in the nuclear medium. A recent application of the theory to the FermiLab E772/E866 experimental data, determining the rate of energy loss of a quark propagating in the medium to be 2 to 3 GeV/fm, will be reviewed. Calculations for the transverse momentum distribution will be presented, and the results will be compared to the E866 data. The theory will be shown to compare favorably to the data, and these results will be shown to suggest that the momentum broadening of a quark is about twice the generally accepted size.Comment: 6 pages, 4 figures, Invited talk given at 4th International Conference on Perspectives in Hadronic Physic

New result on the measurement of the direct photon emission in K+ --> pi^+ pi^0 gamma decay

We present a new result on the K^+ --> pi^+ pi^0 gamma decay measurement using stopped kaons. The best fit to the decay spectrum comprised of 10k events gives a branching ratio for the direct photon emission of [3.8+-0.8(stat)+-0.7(syst)] times 10^{-6} in the pi^+ kinetic energy region of 55 to 90 MeV. This result has been obtained with the assumption that there is no component due to interference with the inner bremsstrahlung.Comment: 14 pages, 7 figures, 3 tables (Fig.1 which had problems with uploading first time is replaced. Besides introduction is changed to bring into accordance with the version published in Eur.Phys.J.C.