Theoretical investigation of the decay of theN(2120)resonance to nucleon resonances near 1.7 GeV

Abstract

Background: Until now the knowledge about nucleon resonances with a mass higher than 2 GeV has been scarce. Huge amounts of experimental data of the multipion photoproduction have been accumulated, and more can be expected in the future in facilities such as JLab 12 GeV. It makes it possible to investigate the decay of a nucleon resonance into another nucleon resonance. Purpose:The possibility to research the decay of the N(2120) to nucleon resonances near 1.7 GeV in the three-pion photoproduction will be explored to provide useful information for future experimental study. Method:The pion and radiative decay amplitudes of nucleon resonances are studied within the constituent quark model, which is used to calculate the couplings constants, especially for the decay of a nucleon resonance near 2.1 GeV to another nucleon resonance near 1.7 GeV. The three-pion photoproduction off the neutron target, i.e.,γn → π − π − ∆ ++ → π − π − π + p, is investigated based on the effective Lagrangian method with the coupling constant obtained form the decay amplitudes. Results:The resonance contribution with a state N( 2 P M ) 3 2 − near 2.1 GeV decaying to a state N( 4 P M ) 5 2 − near 1.7 GeV, i. e., N(2120) → N(1675)π is dominant in the process considered. The total cross section from the resonance contribution is at the order of 1 µb and can be easily distinguished from the background. Conclusions:Our results suggest it is practicable to research the decay of the N(2120) to the N(1675) in experiment.

Study of the a1 (1269) resonance in the γp →π+π+π-n reaction *

“…Since the exact value of is not determined by theory or experiment, in this work we take keV. The result is comparable with the cross-section of photoproduction [41].…”

Nonequilibrium Casimir pressures in liquids under shear

“…(14), for the shear-induced pressure enhancement follows from a solution of the fluctuating hydrodynamics equations for the long-range velocity fluctuations. Numerical solutions of the fluctuating hydrodynamics equations have been obtained some years ago with a direct simulation Monte Carlo method [51,52] and, more recently, by Varghese et al [25] with a multiparticle collision dynamics method [53][54][55]. These approaches apply either to dilute gases [51,52] or to a model fluid with an idealgas equation of state [25], but have the merit of evaluating the Casimir pressure purely mechanically, from momentum exchange in particle-wall collisions.…”

“…However, Wada and Sasa [13] have provided only little details about their calculation for PBC, so that an ultimate explanation is not available. Equations (54) and (55) for the other…”