Nuclear Theory·nucl-th

Friday·September 18, 2020

8 papers—4 primary·4 cross-listed

05
[Submitted on 17 Sept 2020] (cross-list from hep-ph)
Effects of $C P$ -violating internucleon interactions in paramagnetic molecules
V. V. Flambaum🇦🇺 · I. B. Samsonov🇦🇺 · H. B. Tran Tan🇦🇺
We demonstrate that electron electric dipole moment experiments with molecules in paramagnetic state are sensitive to $P, T$ -violating nuclear forces and other $C P$ -violating parameters in the hadronic sector. These experiments, in particular, measure the coupling constant $C_{S P}$ of the $C P$ -odd contact semileptonic interaction. We establish relations between $C_{S P}$ and different $C P$ -violating hadronic parameters including strength constants of the $C P$ -odd nuclear potentials, $C P$ -odd pion-nucleon interactions, quark-chromo EDM and QCD vacuum angle. These relations allow us to find limits on various $C P$ -odd hadronic parameters.
Comments:
13 pages. arXiv admin note: text overlap with arXiv:2004.10359
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
arXiv:
2009.07992 [pdf]
PRD(2020)·11 citations
06
[Submitted on 17 Sept 2020] (cross-list from hep-ph)
Two-photon exchange effects in $e^{+} e^{-} \to π^{+} π^{-}$ at small $s$
Zhong-Hua Zhao🇨🇳 · Hui-Yun Cao🇨🇳 · Hai-Qing Zhou🇨🇳
In this work, the two-photon-exchange (TPE) effects in $e^{+} e^{-} \to π^{+} π^{-}$ at small $s$ are discussed within a hadronic model. In the limit $m_{e} \to 0$ , the TPE contribution to the amplitude can be described by one scalar function $c_{1}^{(2 γ)}$ . The ratio between this function and the corresponding contribution in one-photon exchange $c_{1}^{(1 γ)}$ reflects all the information of the TPE corrections. The numerical results on this ratio are presented and an artificial function is used to fit the numerical results. The latter can be used conveniently in the further experimental data analysis. The numerical results show the asymmetry of the differential cross sections in $e^{+} e^{-} \to π^{+} π^{-}$ is about $- 4%$ at $s \sim 0.7$ GeV.
Comments:
8 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2009.08183 [pdf]
PRC(2020)·1 citation
07
[Submitted on 17 Sept 2020] (cross-list from hep-ph)
Large-P_T inclusive photoproduction of J/psi in electron-proton collisions at HERA and the EIC
Carlo Flore🇫🇷 · Jean-Philippe Lansberg🇫🇷 · Hua-Sheng Shao🇫🇷 · Yelyzaveta Yedelkina🇫🇷
We study the inclusive J/psi production at large transverse momenta at lepton-hadron colliders in the limit when the exchange photon is quasi real, also referred to as photoproduction. Our computation includes the leading-P_T leading-v next-to-leading alpha_s corrections. In particular, we consider the contribution from J/psi plus another charm quark, by employing for the first time in quarkonium photoproduction the variable-flavour-number scheme. We also include a QED-induced contribution via an off-shell photon which remained ignored in the literature and which we show to be the leading contribution at high P_T within the reach of the EIC. In turn, we use our computation of J/psi+charm to demonstrate its observability at the future EIC and the EIC sensitivity to probe the non-perturbative charm content of the proton at high x.
Comments:
LaTeX, 11 pages; 15 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2009.08264 [pdf]
PLB(2020)·49 citations
08
[Submitted on 17 Sept 2020] (cross-list from hep-ph)
Deciphering the mechanism of near-threshold $J / ψ$ photoproduction
Meng-Lin Du🇩🇪 · Vadim Baru🇩🇪 · Feng-Kun Guo🇨🇳 · Christoph Hanhart🇩🇪 · Ulf-G. Meißner🇩🇪 · Alexey Nefediev🇷🇺 · Igor Strakovsky🇺🇸
The photoproduction of the $J / ψ$ off the proton is believed to deepen our understanding of various physics issues. On the one hand, it is proposed to provide access to the origin of the proton mass, based on the QCD multipole expansion. On the other hand, it can be employed in a study of pentaquark states. The process is usually assumed to proceed through vector-meson dominance, that is the photon couples to a $J / ψ$ which rescatters with the proton to give the $J / ψ p$ final state. In this Letter, we provide a compelling hint for and propose measurements necessary to confirm a novel production mechanism via the $Λ_{c} D ˉ^{(*)}$ intermediate states. In particular, there must be cusp structures at the $Λ_{c} D ˉ^{(*)}$ thresholds in the energy dependence of the $J / ψ$ photoproduction cross section. The same mechanism also implies the $J / ψ$ -nucleon scattering lengths of order 1 mfm. Given this, one expects only a minor contribution of charm quarks to the nucleon mass.
Comments:
6 pages, 5 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2009.08345 [pdf]
EPJC(2020)·97 citations

Affiliations

first authorsco-authorsvia INSPIRE

Effects of CP-violating internucleon interactions in paramagnetic molecules

Two-photon exchange effects in e+e−→π+π− at small s​

Large-P_T inclusive photoproduction of J/psi in electron-proton collisions at HERA and the EIC

Deciphering the mechanism of near-threshold J/ψ photoproduction

Affiliations

Effects of $C P$ -violating internucleon interactions in paramagnetic molecules

Two-photon exchange effects in $e^{+} e^{-} \to π^{+} π^{-}$ at small $s$

Deciphering the mechanism of near-threshold $J / ψ$ photoproduction