Parity nonconserving two-pion exchange in elastic proton-proton scattering

Abstract

Parity nonconserving two-pion exchange in elastic pp scattering is investigated in the presence of phenomenological strong distortions in various models. Parity violation is included in N N π vertex considering N N and N ∆(1232) intermediate states in box and crossed box diagrams. Using the derived parity nonconserving two-pion exchange potential we calculate the longitudinal analyzing powerĀ L in elastic pp scattering. The predicted effect is of the same order as vector meson exchanges.

The theory of parity violation in few-nucleon systems

“…Several extensions of the potential have been proposed to also include two-meson-exchange contributions (see, e.g., Refs. [180,181,182] and references therein) and additional degrees of freedom such as the ∆ resonance [183,98,184]. Given the model dependence and the difficulties in determining reliable values for the various couplings, the importance of these additional terms is not clear.…”

Parity-nonconserving cold neutron-parahydrogen interactions

“…Up till recently, the effect of the two-pion exchange has been considered small and neglected from the analyses of the PNC observables. However, recent calculations of the PNC longitudinal analyzing power ĀL in the pp elastic scattering show the importance of the two-pion exchange [13,14]. The PNC pp reaction offers an auspicious opportunity to study the two-pion exchange contribution for a couple of reasons.…”

Parity nonconserving proton-proton elastic scattering

“…In our later work Ref. [11] on PNC pp elastic scattering, we looked at the effects of the N∆-channels in the coupled-channels formalism as well as the effects of the two-pion exchange (TPE). The effects were again found significant and cast doubt on the aforementioned h pp ρ -coupling and whether its value is straightforwardly proportional to the TRIUMF data point.…”

“…As shown in Ref. [11], another possibly noteworthy contribution arises from the ∆-resonance even at low energies, but it is not taken into consideration here in its fullest form because of the large uncertainties related to the meson-N∆ couplings especially in the weak sector. The ∆ is taken into account only to the extent it appears in the PNC TPE potentials.…”

“…For the long-ranged effects, we compare three different PNC TPE potentials on the market given in Refs. [11,25,26]. Note that, besides Ref.…”