Nuclear Theory·nucl-th

Wednesday·June 8, 2022

8 papers—4 primary·4 cross-listed

05
[Submitted on 6 Jun 2022] (cross-list from hep-ph)
A unified picture of medium-induced radiation
Johannes Hamre Isaksen🇳🇴 · Adam Takacs🇳🇴 · Konrad Tywoniuk🇳🇴
We revisit the picture of jets propagating in the quark-gluon plasma. In addition to vacuum radiation, partons scatter on the medium constituents resulting in induced emissions. Analytical approaches to including these interactions have traditionally dealt separately with multiple, soft, or rare, hard scatterings. A full description has so far only been available using numerical methods. We achieve full analytical control of the relevant scales and map out the dominant physical processes in the full phase space. To this aim, we extend existing expansion schemes for the medium-induced spectrum to the Bethe--Heitler regime. This covers the whole phase space from early to late times, and from hard splittings to emissions below the thermal scale. Based on the separation of scales, a space-time picture naturally emerges: at early times, induced emissions start to build from rare scatterings with the medium. At a later stage, induced emissions due to multiple soft scatterings result in a turbulent cascade that rapidly degrades energy down to, and including, the Bethe--Heitler regime. We quantify the impact of such an improved picture, compared to the current state-of-the-art factorization that includes only soft scatterings, by both analytical and numerical methods for the medium-induced energy distribution function. Our work serves to improve our understanding of jet quenching from small to large systems and for future upgrades of Monte Carlo generators.
Comments:
published version, 58 pages, 11 figures, if the figures don't load properly try using a different PDF reader
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2206.02811 [pdf]
JHEP(2023)·25 citations
06
[Submitted on 6 Jun 2022] (cross-list from hep-lat)
Heavy quark diffusion coefficient with gradient flow
Nora Brambilla🇩🇪 · Viljami Leino🇩🇪 · Julian Mayer-Steudte🇩🇪 · Peter Petreczky🇺🇸
We calculate chromo-electric and chromo-magnetic correlators in quenched QCD at $1.5 T_{c}$ and $1 0^{4} T_{c}$ with the aim to estimate the heavy quark diffusion coefficient at leading order in the inverse heavy quark mass expansion, $κ_{E}$ , as well as the coefficient of first mass suppressed correction, $κ_{B}$ . We use gradient flow for noise reduction. At $1.5 T_{c}$ we obtain: $1.70 \leq κ_{E} / T^{3} \leq 3.12$ and $1.03 < κ_{B} / T^{3} < 2.61$ . The latter implies that the mass suppressed effects in the heavy quark diffusion coefficient are 20% for bottom quarks and 34% for charm quark at this temperature.
Comments:
18 pages, 20 figures, updated to match the published version
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2206.02861 [pdf]
PRD(2023)·50 citations
07
[Submitted on 6 Jun 2022] (cross-list from hep-lat)
Study of three-flavored heavy dibaryons using lattice QCD
Parikshit Junnarkar🇩🇪 · Nilmani Mathur🇮🇳
We present results of the first lattice QCD calculation of three-flavored heavy dibaryons both in the flavor-symmetric and antisymmetric channels. These dibaryons have spin zero, and are constructed using various possible combinations of quark flavors with at least one of them as the charm or the bottom quark, i.e., namely, $H_{c} (c u d c u d), H_{b} (b u d b u d), H_{b cs} (b cs b cs)$ , $H_{cs l} (cs l cs l), H_{b s l} (b s l b s l)$ and $H_{b c l} (b c l b c l)$ ; $l \in u, d$ . We compute the ground state masses of these dibaryons and the calculations are performed on three $N_{f} = 2 + 1 + 1$ HISQ gauge ensembles of the MILC collaboration, with lattice spacings $a =$ 0.1207, 0.0888 and 0.0582 fm. A relativistic overlap action is employed for the valence light to charm quarks while a non-relativistic-QCD Hamiltonian with improved coefficients is used for the bottom quarks. Unlike the doubly heavy tetraquarks, one and two-flavored heavy dibaryons, for which lattice QCD calculations have predicted deeply bound strong-interactions-stable states, for these $H_{c}, H_{b}, H_{cs l}, H_{b s l}$ dibaryons we do not find any such deeply bound state. However, for $H_{b cs}$ , our results indicate the presence of an energy level $29 \pm 24$ MeV below the lowest two-baryon threshold, which could be relevant for its future experimental searches. Moreover, we find that the energy difference between the ground state of $H_{b c l}$ and its lowest threshold increases when $m_{l} > m_{s}$ . Taken together, our findings indicate the possibility of the existence of the $H_{b cs}$ dibaryon while all other physical three-flavored dibaryons are much closer to their thresholds suggesting either they are weakly bound or unbound, resolving which requires further detail study. Our results also point that the binding of a dibaryon configuration becomes stronger with the increase of its valence quark masses which suggests an interesting aspect of strong interactions at multiple scales.
Comments:
Version published in Phys. Rev. D
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2206.02942 [pdf]
PRD(2022)·24 citations
08
[Submitted on 7 Jun 2022] (cross-list from astro-ph.HE)
Evaluations of uncertainties in simulations of propagation of ultrahigh-energy cosmic-ray nuclei derived from microscopic nuclear models
E. Kido🇯🇵 · T. Inakura🇯🇵 · M. Kimura🇯🇵 · N. Kobayashi🇯🇵 · S. Nagataki🇯🇵 · N. Shimizu🇯🇵 · A. Tamii🇯🇵 · Y. Utsuno🇯🇵
Photodisintegration is a main energy loss process for ultrahigh-energy cosmic-ray (UHECR) nuclei in intergalactic space. Therefore, it is crucial to understand systematic uncertainty in photodisintegration when simulating the propagation of UHECR nuclei. In this work, we calculated the cross sections using the random phase approximation (RPA) of density functional theory (DFT), a microscopic nuclear model. We calculated the $E 1$ strength of 29 nuclei using three different density functionals. We obtained the cross sections of photonuclear reactions, including photodisintegration, with the $E 1$ strength. Then, we implemented the cross sections in the cosmic-ray propagation code CRPropa. We found that assuming certain astrophysical parameter values, the difference between UHECR energy spectrum predictions using the RPA calculation and the default photodisintegration model in CRPropa can be more than the statistical uncertainty of the spectrum. We also found that the differences between the RPA calculations and CRPropa default in certain astrophysical parameters obtained by a combined fit of UHECR energy spectrum and composition data assuming a phenomenological model of UHECR sources can be more than the uncertainty of the data.
Comments:
37 pages, 16 figures
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2206.03447 [pdf]
Astropart.Phys.(2023)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE

A unified picture of medium-induced radiation

Heavy quark diffusion coefficient with gradient flow

Study of three-flavored heavy dibaryons using lattice QCD

Evaluations of uncertainties in simulations of propagation of ultrahigh-energy cosmic-ray nuclei derived from microscopic nuclear models

Affiliations