Year: 2019
Type: article
Abstract: The parity-violating (PV) nucleon-nucleon $(NN)$ interaction in the three-nucleon system is investigated using pionless effective field theory $(\mathrm{EFT}(\ensuremath{\pi}\phantom{\rule{-0.5em}{0ex}}/))$. This work shows that a next-to-leading order (NLO) PV three-body force is necessary, in contradiction with a previous claim [H. W. Grie\ss{}hammer and M. R. Schindler, Eur. Phys. J. A 46, 73 (2010)]. Including three-body $P$- to $D$-wave transitions, PV three-nucleon observables are calculated to higher energies than previously considered. Using the recent large-${N}_{C}$ analysis of the PV $NN$ interaction in $\mathrm{EFT}(\ensuremath{\pi}\phantom{\rule{-0.5em}{0ex}}/)$, the current understanding of low energy PV few-body measurements is reassessed. The recent measurement of the asymmetry ${A}_{\ensuremath{\gamma}}$ in $\stackrel{P\vec}{n}p\ensuremath{\rightarrow}d\ensuremath{\gamma}$ from the NPDGamma Collaboration [D. Blyth et al. (NPDGamma), Phys. Rev. Lett. 121, 242002 (2018)], gives the value ${g}_{4}^{({N}_{C}^{\ensuremath{-}1})}=[\ensuremath{-}1.4\ifmmode\pm\else\textpm\fi{}0.63(\text{stat.})\ifmmode\pm\else\textpm\fi{}0.09(\text{syst.})]\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}\phantom{\rule{0.28em}{0ex}}{\mathrm{MeV}}^{\ensuremath{-}1}$ for a next-to-next-to-leading order $({\mathrm{N}}^{2}\mathrm{LO})$ in large-${N}_{C}$ low energy constant (LEC). Using the large-${N}_{C}$ hierarchy of LECs, the sizes of the leading order (LO) in large-${N}_{C}$ LECs are estimated using an experimental bound on a parity violating asymmetry in $\stackrel{P\vec}{p}d$ scattering at ${E}_{\mathrm{lab}}=15$ MeV and a measurement of $\stackrel{P\vec}{p}p$ scattering at ${E}_{\mathrm{lab}}=13.6$ MeV. Comparing the size of the resulting $\mathrm{LO}(\mathcal{O}({N}_{C}))$ in large-${N}_{C}$ LECs to the ${\mathrm{N}}^{2}\mathrm{LO}(\mathcal{O}({N}_{C}^{\ensuremath{-}1}))$ in large-${N}_{C}$ LEC ${g}_{4}^{({N}_{C}^{\ensuremath{-}1})}$ shows they are roughly the same size, in contradiction with current large-${N}_{C}$ counting.
Source: Physical Review C
Author: Jared Vanasse
Institution: Stetson University
Language: Latvian
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2893844148