Thu·Mar 31, 2022Thursday·March 31, 2022

1. 01*

   Ab initio prediction of the ${}^4\mathrm{He}(d,\gamma ){}^6\mathrm{Li}$ big bang radiative capture

   Chloë Hebborn🇺🇸 · Guillaume Hupin🇫🇷 · Konstantinos Kravvaris🇺🇸 · Sofia Quaglioni🇺🇸 · Petr Navrátil🇨🇦 · Peter Gysbers🇨🇦

   The rate at which helium (${}^4$He) and deuterium ($d$) fuse together to produce lithium-6 (${}^6$Li) and a $\gamma$ ray, ${}^4$He$(d,\gamma {)}^6$Li, is a critical puzzle piece in resolving the roughly three orders of magnitude discrepancy between big bang predictions and astronomical observations for the primordial abundance of ${}^6$Li. The accurate determination of this radiative capture rate requires the quantitative and predictive description of the fusion probability across the big bang energy window ($30$ keV $\lesssim E\lesssim 400$ keV), where measurements are hindered by low counting rates. We present first-principles (or, ab initio) predictions of the ${}^4$He$(d,\gamma {)}^6$Li astrophysical S-factor using validated nucleon-nucleon and three-nucleon interactions derived within the framework of chiral effective field theory. By employing the ab initio no-core shell model with continuum to describe ${}^4\mathrm{He}$-$d$ scattering dynamics and bound ${}^6\mathrm{Li}$ product on an equal footing, we accurately and consistently determine the contributions of the main electromagnetic transitions driving the radiative capture process. Our results reveal an enhancement of the capture probability below 100 keV owing to previously neglected magnetic dipole (M1) transitions and reduce by an average factor of 7 the uncertainty of the thermonuclear capture rate between $0.002$ and $2$ GK.

   ↳ nucl-thnucl-exPRL(2022)·36 citations
2. 02*

   Heavy quarks and jets as probes of the QGP

   Liliana Apolinário (1 and 2)🇵🇹 · Yen-Jie Lee (3)🇺🇸 · Michael Winn (4) ((1) LIP, (2) Instituto Superior Técnico (IST), Universidade de Lisboa, (3) Massachusetts Institute of Technology (MIT), (4) Département de Physique Nucléaire (DPhN), Institut de Recherche sur les lois Fondamentales de l'Univers (IRFU) CEA - Saclay)🇫🇷

   Quark-Gluon Plasma (QGP), a QCD state of matter created in ultra-relativistic heavy-ion collisions, has remarkable properties, including, for example, a low shear viscosity over entropy ratio. By detecting the collection of low-momentum particles that arise from the collision, it is possible to gain quantitative insight into the created matter. However, its fast evolution and thermalization properties remain elusive. Only using high momentum objects as probes of QGP can unveil its constituents at different wavelengths. In this review, we attempt to provide a comprehensive picture of what was, so far, possible to infer about QGP given our current theoretical understanding of jets, heavy-flavor, and quarkonia. We will bridge the resulting qualitative picture to the experimental observations done at the LHC and RHIC. We will focus on the phenomenological description of experimental observations, provide a brief analytical summary of the description of hard probes, and an outlook on the main difficulties we will need to surpass in the following years. To benchmark QGP-related effects, we will also address nuclear modifications to the initial state and hadronization effects.

   ↳ hep-phnucl-exnucl-thPPNP(2022)·215 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.