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A new momentum-space formulation for scattering of two spin-half particles, both either identical or unidentical, is formulated. As basis states the free linear-momentum states are not expanded into the angular-momentum states, the system's spin states are described by the product of the spin states of the two particles, and the system's isospin states by the total isospin states of the two particles. We evaluate the Lippmann-Schwinger equations for the T-matrix elements in these basis states. The azimuthal behavior of the potential and of the T-matrix elements leads to a set of coupled integral equations for the T-matrix elements in two variables only, which are the magnitude of the relative momentum and the scattering angle. Some symmetry relations for the potential and the T-matrix elements reduce the number of the integral equations to be solved. A set of six spin operators to express any interaction of two spin-half particles is introduced. We show the spin-averaged differential cross section as being calculated in terms of the solution of the set of the integral equations. [ABSTRACT FROM AUTHOR]

We advocate the use of the T -matrix of the pair potential to study the properties of ultracold Fermi gases in the mean-field approximation. Our approach does not require renormalization procedures even in the limit of contact interaction, and it provides a rigorous definition of the range of the potential. We also rewrite the Bogoliubov-de Gennes equation for the pairing function as a function of the T-matrix, and use it to investigate finite-range effects on the main thermodynamic observables in a gas of 6Li atoms at unitarity, calculating the pair potential with ab initio quantum chemical methods. [ABSTRACT FROM AUTHOR]

We assess transport properties of heavy quarks in the Quark-Gluon Plasma (QGP) that show a strong non-perturbative behavior. A T-matrix approach based on a potential taken from lattice QCD hints at the presence of heavy-quark (HQ) resonant scattering with an increasing strength as the temperature, T, reaches the critical temperature, Tc ⋍ 170 MeV for deconfinement from above. The implementation of HQ resonance scattering along with a hadronization via quark coalescence under the conditions of the plasma created in heavy-ion collisions has been shown to correctly describe both the nuclear modification factor, RAA, and the elliptic flow, ν2, of single electrons at RHIC and have correctly predicted the RAA of D mesons at LHC energy. [ABSTRACT FROM AUTHOR]

We measured the polarization-transfer coefficient Kyy′ of the fusion reaction 2H(dvector , pvector )3H at the fusion relevant energy of Ed = 58 keV at the laboratory reaction angle θ = 45°. The result is compared with theoretical predictions based on Faddeev-Yakubovsky equations, calculated with and without inclusion of the Coulomb interaction, and a prediction based on a T-matrix parametrization of all available data of this reaction at energies below 1500 keV. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]