arXiv subjects
Publications and source records attributed to Antonio O. Bouzas.
We compute the polarization of the final-state baryon, in its rest frame, in low-energy meson--baryon scattering with unpolarized initial state, in Unitarized BChPT. Free parameters are determined by fitting total and differential cross-section data (and spin-asymmetry or polarization data if available) for $pK^-$, $pK^+$ and $pπ^+$ scattering. We also compare our results with those of leading-order BChPT.
We compute the spin asymmetry and polarization of the final-state baryon in its rest frame in two-body meson--baryon low-energy scattering with unpolarized initial state, to lowest non-trivial order in BChPT. The required absorptive amplitudes are obtained analytically at one-loop level. We discuss the polarization results numerically for several meson--baryon processes. Even at low energies above threshold, where BChPT can reasonably be expected to be applicable, sizable values of polarization are found for some processes.
A mechanism is discussed to obtain light scalar fields from a spontaneously broken continuous symmetry without explicitly breaking it. If there is a continuous manifold of classical vacua in orbit space, its tangent directions describe classically massless fields that may acquire mass from perturbations of the potential that do not break the symmetry. We consider the simplest possible example, involving a scalar field in the adjoint representation of SU(N). We study the scalar mass spectrum and its RG running at one-loop level including scalar and pseudoscalar Yukawa couplings to a massive Dirac fermion.
We study the quantization of three-dimensional many-body systems in rotating coordinate frames defined implicitly by frame conditions. We carry out the elimination of orientational degrees of freedom in general, giving the Hamiltonian for the $N$-particle system in a broad class of body frames in terms of frame conditions and internal coordinates. We obtain several forms for the kinetic energy operator and compare them to related expressions in the literature.
We study the quantization of many-body systems in three dimensions in rotating coordinate frames using a gauge invariant formulation of the dynamics. We consider reference frames defined by linear gauge conditions, and discuss their Gribov ambiguities and commutator algebra. We construct the momentum operators, inner-product and Hamiltonian in those gauges, for systems with and without translation invariance. The analogy with the quantization of non-Abelian Yang-Mills theories in non-covariant gauges is emphasized. Our results are applied to quasi-rigid systems in the Eckart frame.
We consider the renormalization of theories with many scalar fields. We discuss at the one-loop level some simple, non-gauge models with an arbitrary number of scalars and fermions both in mass-shell and MS schemes. In MS scheme we give a detailed qualitative analysis of the RG flow of dimensionless couplings in flavor space.
We study the quantization of many-body systems in two dimensions in rotating coordinate frames using a gauge invariant formulation of the dynamics. We consider reference frames defined by linear and quadratic gauge conditions. In both cases we discuss their Gribov ambiguities and commutator algebra. We construct the momentum operators, inner-product and Hamiltonian in both types of gauges, for systems with and without translation invariance. The analogy with the quantization of QED in non-covariant gauges is emphasized. Our results are applied to quasi-rigid systems in the Eckart frame.
We study the renormalization of normal mixing matrices, which includes hermitian and unitary matrices as particular cases. We give a minimal, multiplicative parametrization of counterterms, and compute the renormalized Lagrangian to one-loop order in several models with N species of fermions, both in on-shell and MS schemes. In on-shell scheme the mass-degenerate case is considered separately.
We give a complete analytical computation of three-point one-loop integrals with one heavy propagator, up to the third tensor rank, for arbitrary values of external momenta and masses.
We give the results of complete analytical computations of two- and three-point loop integrals ocurring in heavy particle theories, with and without velocity change, for arbitrary values of external momenta and masses.
A current algebra sum rule for inclusive decays \bar B --> D + X + \ell + \bar νby Bjorken et al. is used to obtain constraints on the Isgur-Wise function ξ(ω) for \bar B --> D \ell \bar νdecays.
We consider unstable-particle scattering in the context of 3-body processes. We show that all partial-wave cross-sections are finite and positive, and the total cross-section is proportional to the transverse size of space in the region of on-shell particle exchange. We comment on the role of loop corrections.