Showing papers by "T.T.S. Kuo published in 2004"

Family of Hermitian low-momentum nucleon interactions with phase shift equivalence

Abstract: Using a Schmidt orthogonalization transformation, a family of Hermitian low-momentum nucleon-nucleon ($NN$) interactions is derived from the non-Hermitian Lee-Suzuki (LS) low-momentum $NN$ interaction. As special cases, our transformation reproduces the Hermitian interactions of Okubo and Andreozzi. Aside from their common preservation of the deuteron binding energy, these Hermitian interactions are shown to be phase shift equivalent, all preserving the empirical phase shifts up to decimation scale $\ensuremath{\Lambda}$. Employing a solvable matrix model, the Hermitian interactions given by different orthogonalization transformations are studied; the interactions can be very different from each other particularly when there is a strong intruder state influence. However, because the parent LS low-momentum $NN$ interaction is only slightly non-Hermitian, the Hermitian low-momentum nucleon interactions given by our transformations, including the Okubo and Andreozzi ones, are all rather similar to each other. Shell model matrix elements given by the LS and several Hermitian low-momentum interactions are compared.

Generalized Seniority Description of Cold Fermi Gases

Abstract: We suggest that the extension of the Racah seniority description of strongly interacting fermions in the nuclear shell model is directly generalizable to describe pairing of atoms in cold Fermi systems. We illustrate this by the fermionic pairing in the much studied cold two-component gas of Li atoms. Our pairing interaction is two orders of magnitude stronger than that used in the usual BCS approach. We also explain why the Racah scheme is less applicable to nuclei, and discuss the similarities of the strongly-coupled matter in cold fermion systems and the new form of matter found in RHIC close to T_c.