Fri·Sep 20, 2019Friday·September 20, 2019

1. 01*

   Two Pion Photo- and Electroproduction with CLAS

   Victor I Mokeev🇺🇸

   Exclusive ${\pi }^{+}{\pi }^{-}p$ photo- and electroproduction data from CLAS have considerably extended the information on the spectrum and structure of nucleon resonances. The data from the ${\pi }^{+}{\pi }^{-}p$ and $N\pi$ channels have provided results on the electrocouplings of most resonances in the mass region up to 1.8 GeV and at photon virtualities up to 5.0 GeV${}^2$. The recent CLAS data on ${\pi }^{+}{\pi }^{-}p$ photoproduction have improved knowledge on the photocouplings of nucleon resonances in the mass range of 1.6 GeV $<$ $M_{N^{\ast }}$ $<$ 2.0 GeV and on their decays to the $\pi \Delta$ and $\rho p$ final hadron states. For the first time, the electrocouplings of the $N(1440)1/2^{+}$ and $N(1520)3/2^{-}$ excited states have become available from ${\pi }^{+}{\pi }^{-}p$ data at 2.0 GeV${}^2$ $<$ $Q^2$ $<$ 5.0 GeV${}^2$. Analyses of the combined ${\pi }^{+}{\pi }^{-}p$ photo- and electroproduction data have revealed evidence for the candidate-state $N^{\prime }(1720)3/2^{+}$. The new results on the nucleon resonance spectrum, electroexcitation amplitudes from analysis of the CLAS ${\pi }^{+}{\pi }^{-}p$ photo- and electroproduction data, and their impact on the exploration of strong QCD are presented.

   nucl-exhep-ph4 citations
2. 02*

   Inclusive and diffractive dijet photoproduction in UPCs at the LHC in NLO QCD

   V. Guzey🇷🇺 · M. Klasen🇩🇪

   We present a next-to-leading order QCD calculation of inclusive dijet photoproduction in ultraperipheral Pb-Pb collisions at the LHC and show that the results agree very well with various kinematic distributions measured by the ATLAS collaboration. The effect of including these data in nCTEQ or EPPS16 nuclear parton density functions (nPDFs) is then studied using the Bayesian reweighting technique. For an assumed total error of 5\% on the final data, its inclusion would lead to a significant reduction of the nPDF uncertainties of up to a factor of two at small values of the parton momentum fraction. As an outlook, we discuss future analyes of diffractive nPDFs, which are so far completely unknown.

   ↳ hep-phhep-exnucl-exnucl-thPoS(2020)·3 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.