123745795
*recoil effects* in a model of higher baryon couplings. i. photoproduction
A recently proposed model (MM) of higher baryon couplings for P and V mesons is reformulated by reviewing the fuller possibilities of the "recoil term" in the primitive quark-meson interaction. While this introduces no basic change in the P-meson coupling structures, it yields an entirely new (L-1)-wave coupling of V mesons to J = L+12 baryons, which is capable of generating helicity-flip amplitudes. The advantage of this new coupling structure over the earlier one is demonstrated through the excellent reproduction of (i) the E1 angular distribution in Y * →Λγ decay and (ii) the appreciable magnitudes as well as energy variations of the asymmetry parameter ∑(θ) in pion photoproduction. In addition to a comparison of the two coupling structures (old and new), the present paper is also designed to study the role of still another parametric structure for the form factor - one which exhibits better convergence properties at higher energies than those discussed in MM. The additional processes studied in this connection are (i) η and X 0 photoproduction at intermediate energies (> 2 GeV), (ii) polarization of the recoil proton in η and π photoproduction, and (iii) π 0 photoproduction at high energies (∼ 6 GeV), in accordance with our earlier scheme of s-channel resonances. In connection with η photoproduction the roles of some pertinent I =12 resonances such as S 11 , P 11 , and G 17 are discussed, especially in relation to supermultiplet assignments.
118644850
Efimov Trimers : Analytic Solution Via Separable Potentials
The exact dynamical equation for Efimov trimers in the short range limit of dimer resonances is derived via Yamaguchi separable potentials. This equation which overcomes the non-uniqueness problem of zero-range potentials, closely resembles one derived recently by Gogolin et al, with no further assumptions, and hence enjoys all the benefits of the latter results.
122943997
Backward pd scattering with a realistic model of N and N∗ exchanges
The differential cross section for pd scattering in the GeV range has been calculated in terms of the contributions of N and N∗ exchanges. For the N-exchange contribution a relativistic deuteron from factor with appropriate S- and D-wave components is employed. For the N∗ exchanges, which are calculated in terms of a model of dNN∗ vertex developed separately by one of us (ANM), all the observed I = 12 resonances up to 2 GeV (both positive and negative parities) are taken into account. The agreement with experiment at 1 GeV is extremely good over the entire angular range, a result in which contributions of the P11, P′11 and D13 exchanges are found to be extremely important. At a higher energies, while the agreement is good near the backward direction, the F15 exchange produces some distortion at intermediate angles. A possible mechanism for correcting the discrepancy is suggested.
61725309
The three-body problem: third generation and beyond?
181778573
HARMONIC OSCILLATOR IN QUARK PHYSICS: SOME ASPECTS, A REVIEW
579271
Temperature Dependence of Gluon and Quark Condensates as from Linear Confinement
The gluon and quark condensates and their temperature dependence are investigated within QCD premises. The input for the former is a gauge invariant $gg$ kernel made up of the direct (D), exchange (X) and contact(C) QCD interactions in the lowest order, but with the perturbative propagator $k^{-2}$ replaced by a `non-perturbative $k^{-4}$ form obtained via two differentiations: $ \mu^2 \partial_m^2 (m^2+k^2)^{-1}$, ($\mu$ a scale parameter), and then setting $m=0$, to simulate linear confinement. Similarly for the input $q{\bar q}$ kernel the gluon propagator is replaced by the above $k^{-4}$ form. With these `linear' simulations, the respective condensates are obtained by `looping' up the gluon and quark lines in the standard manner. Using Dimensional regularization (DR), the necessary integrals yield the condensates plus temperature corrections, with a common scale parameter $\mu$ for both. For gluons the exact result is $$ = {36\mu^4}\pi^{-3}\alpha_s(\mu^2)[2-\gamma - 4\pi^2 T^2/(3\mu^2)]$$. Evaluation of the quark condensate is preceded by an approximate solution of the SDE for the mass function $m(p)$, giving a recursive formula, with convergence achieved at the third iteration. Setting the scale parameter $\mu$ equal to the universal Regge slope $1 GeV^2$, the gluon and quark condensates at T=0 are found to be $0.586 Gev^4$ and $(240-260 MeV)^3$ respectively, in fair accord with QCD sum rule values. Next, the temperature corrections (of order $-T^2$ for both condensates) is determined via finite-temperature field theory a la Matsubara. Keywords: Gluon Condensate, mass tensor, gauge invariance, linear confinement, finite-temperature, contour-closing. PACS: 11.15.Tk ; 12.38.Lg ; 13.20.Cz
119114701
Localisation of the Galilean symmetry and dynamical realisation of Newton-Cartan geometry
Newtonian gravity was formulated as a geometrodynamic theory as far back in 1930s by Elie Cartan in what is named aptly as Newton Cartan space time. Though there are several approaches of realizing the algebraic structure of the Newton Cartan geometry from a contraction of the relativistic results, a dynamical (field theoretic) realization of it is lacking. In this paper we present such a realization from the localisation of the Galilean Symmetry of nonrelativistic matter field theories.