Wed·Sep 9, 2020Wednesday·September 9, 2020

1. 01*

   Precision measurements of A=3 nuclei in Hall B

   Or Hen (Massachusetts Institute of Technology) · Dave Meekins (Jefferson Lab) · Dien Nguyen (Massachusetts Institute of Technology) · Eli Piasetzky (Tel-Aviv Univ.) · Axel Schmidt (The George Washington Univ.) · Holly Szumila-Vance (Jefferson Lab) · Lawrence Weinstein (Old Dominion Univ.) · Sheren Alsalmi (King Saud Univ.) · Carlos Ayerbe-Gayoso (Mississippi State Univ.) · Lamya Baashen (Florida International Univ.) · Arie Beck (Nuclear Research Center Negev) · Sharon Beck (Nuclear Research Center Negev) and 46 other authors

   We propose a high-statistics measurement of few body nuclear structure and short range correlations in quasi-elastic scattering at 6.6 GeV from ${}^2$H, ${}^3$He and ${}^3$H targets in Hall B with the CLAS12 detector. We will measure absolute cross sections for $(e,e^{\prime }p)$ and $(e,e^{\prime }pN)$ quasi-elastic reaction channels up to a missing momentum $p_{miss}\approx 1$ GeV/c over a wide range of $Q^2$ and $x_B$ and construct the isoscalar sum of ${}^3$H and ${}^3$He. We will compare $(e,e^{\prime }p)$ cross sections to nuclear theory predictions using a wide variety of techniques and $NN$ interactions in order to constrain the $NN$ interaction at short distances. We will measure $(e,e^{\prime }pN)$ quasi-elastic reaction cross sections and $(e,e^{\prime }pN)/(e,e^{\prime }p)$ ratios to understand short range correlated (SRC) $NN$ pairs in the simplest non-trivial system. ${}^3$H and ${}^3$He, being mirror nuclei, exploit the maximum available isospin asymmetry. They are light enough that their ground states are readily calculable, but they already exhibit complex nuclear behavior, including $NN$ SRCs. We will also measure ${}^2$H$(e,e^{\prime }p)$ in order to help theorists constrain non-quasielastic reaction mechanisms in order to better calculate reactions on $A=3$ nuclei. Measuring all three few body nuclei together is critical, in order to understand and minimize different reaction effects, such as single charge exchange final state interactions, in order to test ground-state nuclear models. We will also measure the ratio of inclusive $(e,e^{\prime })$ quasi-elastic cross sections (integrated over $x_B$) from ${}^3$He and ${}^3$H in order to extract the neutron magnetic form factor $G_M^n$ at small and moderate values of $Q^2$. We will measure this at both 6.6 GeV and 2.2 GeV.

   nucl-ex1 citation
2. 02*

   Effects of centrality fluctuation and deuteron formation on proton number cumulant in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 3 GeV from JAM model

   Arghya Chatterjee🇨🇳 · Yu Zhang🇨🇳 · Hui Liu🇨🇳 · Ruiqin Wang🇨🇳 · Shu He🇨🇳 · Xiaofeng Luo🇨🇳

   We studied the effects of centrality fluctuation and deuteron formation on the cumulants ($C_n$) and correlation functions (${\kappa }_n$) of protons up to sixth order in most central ($b<3$ fm) Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 3 GeV from a microscopic transport model (JAM). The results are presented as a function of rapidity acceptance within transverse momentum $0.4<p_T<2$ GeV/$c$. We compared the results obtained by centrality bin width correction (CBWC) using charged reference particle multiplicity with CBWC done using impact parameter bins. It was found that at low energies the centrality resolution for determining the collision centrality using charged particle multiplicities is not good enough to reduce the initial volume fluctuations effect for higher-order cumulant analysis. New methods need to be developed to classify events with high centrality resolution for heavy-ion collisions at low energies. Finally, we observed that the formation of deuteron will suppress the higher-order cumulants and correlation functions of protons and is found to be similar to the efficiency effect. This work can serve as a noncritical baseline for the QCD critical point search at the high baryon density region.

   nucl-exnucl-thCPC(2021)·13 citations
3. 03*

   New opportunities at the photon energy frontier

   Jaroslav Adam · Christine Aidala · Aaron Angerami · Benjamin Audurier · Carlos Bertulani · Christian Bierlich · Boris Blok · James Daniel Brandenburg · Stanley Brodsky · Aleksandr Bylinkin · Veronica Canoa Roman · Francesco Giovanni Celiberto and 63 other authors

   Ultra-peripheral collisions (UPCs) involving heavy ions and protons are the energy frontier for photon-mediated interactions. UPC photons can be used for many purposes, including probing low-$x$ gluons via photoproduction of dijets and vector mesons, probes of beyond-standard-model processes, such as those enabled by light-by-light scattering, and studies of two-photon production of the Higgs.

   ↳ hep-phhep-exnucl-ex34 citations
4. 04*

   Modified lepton couplings and the Cabibbo-angle anomaly

   Antonio Coutinho🇨🇭 · Andreas Crivellin🇨🇭 · Claudio Andrea Manzari🇨🇭

   Significant discrepancies between the different determinations of the Cabibbo angle have been observed. Here, we point out that this "Cabibbo-angle anomaly" can be explained by lepton flavour universality (LFU) violating New Physics (NP) in the neutrino sector. However, modified neutrino couplings to Standard Model gauge bosons also affect many other observables sensitive to LFU violation, which have to be taken into account in order to assess the viability of this explanation. Therefore, we perform a model-independent Bayesian global analysis and find that non-zero modifications of electron and muon neutrino couplings are preferred at more than $99.99\%C.L.$ (corresponding to more than $4\sigma$). Our results show that constructive effects in the muon sector are necessary, meaning simple models with right-handed neutrinos are discarded and more sophisticated NP models required.

   ↳ hep-phhep-exhep-latnucl-ex+1PoS(2021)·18 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.