Thu·Feb 21, 2019Thursday·February 21, 2019

1. 01*

   Conference Summary of QNP2018

   S. Kumano (KEK/J-PARC)🇯🇵

   This report is the summary of the Eighth International Conference on Quarks and Nuclear Physics (QNP2018). Hadron and nuclear physics is the field to investigate high-density quantum many-body systems bound by strong interactions. It is intended to clarify matter generation of universe and properties of quark-hadron many-body systems. The QNP is an international conference which covers a wide range of hadron and nuclear physics, including quark and gluon structure of hadrons, hadron spectroscopy, hadron interactions and nuclear structure, hot and cold dense matter, and experimental facilities. First, I introduce the current status of the hadron and nuclear physics field related to this conference. Next, the organization of the conference is explained, and a brief overview of major recent developments is discussed by selecting topics from discussions at the plenary sessions. They include rapidly-developing field of gravitational waves and nuclear physics, hadron interactions and nuclear structure with strangeness, lattice QCD, hadron spectroscopy, nucleon structure, heavy-ion physics, hadrons in nuclear medium, and experimental facilities of EIC, GSI-FAIR, JLab, J-PARC, Super-KEKB, and others. Nuclear physics is at a fortunate time to push various projects at these facilities. However, we should note that the projects need to be developed together with related studies in other fields such as gravitational physics, astrophysics, condensed-matter physics, particle physics, and fundamental quantum physics.

   ↳ hep-phhep-exnucl-exnucl-thJPS Conf.Proc.(2019)·0 citations
2. 02*

   Impact of form factor uncertainties on interpretations of coherent elastic neutrino-nucleus scattering data

   D. Aristizabal Sierra🇨🇱 · Jiajun Liao🇨🇳 · D. Marfatia🇺🇸

   The standard model coherent elastic neutrino-nucleus scattering (CE$\nu$NS) cross section is subject to nuclear form factor uncertainties, mainly driven by the root-mean-square radius of the neutron density distribution. Motivated by COHERENT phases I-III and future multi-ton direct detection dark matter searches, we evaluate these uncertainties in cesium iodide, germanium, xenon and argon detectors. We find that the uncertainties become relevant for momentum transfers $q\gtrsim 20$ MeV and are essentially independent of the form factor parameterization. Consequently, form factor uncertainties are not important for CE$\nu$NS induced by reactor or solar neutrinos. Taking into account these uncertainties, we then evaluate their impact on measurements of CE$\nu$NS at COHERENT, the diffuse supernova background (DSNB) neutrinos and sub-GeV atmospheric neutrinos. We also calculate the relative uncertainties in the number of COHERENT events for different nuclei as a function of recoil energy. For DSNB and atmospheric neutrinos, event rates at a liquid argon detector can be uncertain to more than 5%. Finally, we consider the impact of form factor uncertainties on searches for nonstandard neutrino interactions, sterile neutrinos and neutrino generalized interactions. We point out that studies of new physics using CE$\nu$NS data are affected by neutron form factor uncertainties, which if not properly taken into account may lead to the misidentification of new physics signals. The uncertainties quantified here are also relevant for dark matter direct detection searches.

   ↳ hep-phhep-exnucl-exnucl-thJHEP(2019)·104 citations
3. 03*

   Benchmarking a Non-Equilibrium Approach to Photon Emission in Relativistic Heavy-Ion Collisions

   Anna Schäfer🇩🇪 · Juan M. Torres-Rincon🇺🇸 · Jonas Rothermel🇩🇪 · Niklas Ehlert🇩🇪 · Charles Gale🇨🇦 · Hannah Elfner🇩🇪

   In this work, the production of photons through binary scattering processes is investigated for equilibrated hadronic systems. More precisely, a non-equilibrium hadronic transport approach to describe relativistic heavy-ion collisions is benchmarked with respect to photon emission. Cross sections for photon production in $\pi +\rho \to \pi +\gamma$ and $\pi +\pi \to \rho +\gamma$ scattering processes are derived from an effective chiral field theory and implemented into the hadronic transport approach, SMASH (Simulating Many Accelerated Strongly-interacting Hadrons). The implementation is verified by systematically comparing the thermal photon rate to theoretical expectations. Further, the impact of form factors is discussed, scattering processes mediated by $\omega$ mesons are found to contribute significantly to the total photon production. Several comparisons of the yielded photon rates are performed: to parametrizations of the very same rates, as used in hydrodynamic simulations, to previous works relying on different cross sections for the production of direct photons from the hadronic stage, and to partonic rates. Finally, the impact of considering the finite width of the $\rho$ meson is investigated, where a significant enhancement of photon production in the low-energy region is observed. This benchmark is the first step towards a consistent treatment of photon emission in hybrid hydrodynamics+transport approaches and a genuine dynamical description.

   ↳ nucl-thhep-phnucl-exPRD(2019)·27 citations
4. 04*

   Neutron Skin in CsI and Low-Energy Effective Weak Mixing Angle from COHERENT Data

   Xu-Run Huang🇨🇳 · Lie-Wen Chen🇨🇳

   Both the neutron skin thickness $\Delta R_{np}$ of atomic nuclei and the low-energy neutrino-nucleon ($\nu N$) interactions are of fundamental importance in nuclear and particle physics, astrophysics as well as new physics beyond the standard model (SM) but largely uncertain currently, and the coherent elastic neutrino-nucleus scattering (CE$\nu$NS) provides a clean way to extract their information. New physics beyond the SM may cause effectively a shift of the SM weak mixing angle ${\theta }_W$ in low-energy $\nu N$ interactions, leading to an effective weak mixing angle ${\theta }_W^{\ast }$. By analyzing the CE$\nu$NS data of the COHERENT experiment, we find that while a one-parameter fit to the COHERENT data by varying $\Delta R_{np}$ produces $\Delta R_{np}^{\mathrm{CsI}}\simeq 0.68_{-1.13}^{+0.91}$ fm for CsI with an unrealistically large central value by fixing ${\sin }^2{\theta }_W^{\ast }$ at the low-energy SM value of ${\sin }^2{\theta }_W^{\mathrm{SM}}=0.23857$, a two-dimensional fit by varying $\Delta R_{np}$ and ${\sin }^2{\theta }_W^{\ast }$ leads to a strong positive correlation between $\Delta R_{np}$ and ${\sin }^2{\theta }_W^{\ast }$ with significantly smaller central values of $\Delta R_{np}^{\mathrm{CsI}}\simeq 0.24_{-2.03}^{+2.30}$ fm and ${\sin }^2{\theta }_W^{\ast }=0.21_{-0.10}^{+0.13}$. Although the uncertainty is too large to claim a determination of $\Delta R_{np}^{\mathrm{CsI}}$ and ${\sin }^2{\theta }_W^{\ast }$, the present study suggests that the multi-dimensional fit is important in future analyses of high-precision CE$\nu$NS data. The implication of the possible deviation of ${\sin }^2{\theta }_W^{\ast }$ from ${\sin }^2{\theta }_W^{\mathrm{SM}}$ on new physics beyond the SM is also discussed.

   ↳ hep-phastro-ph.SRnucl-exnucl-thPRD(2019)·45 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.