Nuclear Theory·nucl-th

Wednesday·March 16, 2022

9 papers—1 primary·8 cross-listed

01
Model for collective motion
Z. P. Li · D. Vretenar
Collective motion is a manifestation of emergent phenomena in medium-heavy and heavy nuclei. A relatively large number of constituent nucleons contribute coherently to nuclear excitations (vibrations, rotations) that are characterized by large electromagnetic moments and transition rates. Basic features of collective excitations are reviewed, and a simple model introduced that describes large-amplitude quadrupole and octupole shape dynamics, as well as the dynamics of induced fission. Modern implementations of the collective Hamiltonian model are based on the microscopic framework of energy density functionals, that provide an accurate global description of nuclear ground states and collective excitations. Results of illustrative calculations are discussed in comparison with available data.
nucl-th0 citations
02
Nuclear effects in the deuteron and global QCD analyses
S.I. Alekhin🇩🇪 · S.A. Kulagin🇷🇺 · R. Petti🇺🇸
We report the results of a new global QCD analysis, which includes deep-inelastic $e / μ$ scattering data off proton and deuterium, as well as Drell-Yan lepton pair production in proton-proton and proton-deuterium collisions and $W^{\pm} / Z$ boson production data from $pp$ and $p p ˉ$ collisions at the LHC and Tevatron. Nuclear effects in the deuteron are treated in terms of a nuclear convolution approach with bound off-shell nucleons within a weak binding approximation. The off-shell correction is controlled by a universal function of the Bjorken variable $x$ describing the modification of parton distributions in bound nucleons, which is determined in our analysis along with the parton distribution functions of the proton. A number of systematic studies are performed to estimate the uncertainties arising from the use of various deuterium datasets, from the modeling of higher twist contributions to the structure functions, from the treatment of target mass corrections, as well as from the nuclear corrections in the deuteron. We obtain predictions for the ratios $F_{2}^{n} / F_{2}^{p}$ , and $d / u$ , focusing on the region of large $x$ . We also compare our results with the ones obtained by other QCD analyses, as well as with the recent data from the MARATHON experiment.
↳ hep-phnucl-thPRD(2022)·22 citations
03
Heavy Elements -- They came out of the blue
Camilla Juul Hansen
How are the heavy elements formed? This has been a key open question in physics for decades. Recent direct detections of neutron star mergers and observations of evolved stars show signatures of chemical elements in the blue range of their spectra that bear witness of recent nuclear processes that led to heavy element production. The formation of heavy elements typically takes place through neutron-capture reactions creating radioactive isotopes, which following beta-decay turn into the stable isotopes we today can measure indirectly in the surfaces of cool, low-mass stars or meteoritic grains. The conditions (such as the neutron density or entropy) of these n-capture reactions remains to date poorly constrained, and only through a multidisciplinary effort can we, by combining and comparing observations, experiments, and theoretical predictions, improve on one of the top 10 most important open physics questions posed at the turn of the century. This emphasises the need for detailed observations of the near-UV to blue wavelength region. The shortage of spectrographs and hence spectra covering this range with high-resolution and high signal-to-noise has for decades played a limiting factor in our understanding of how heavy elements form in the nuclear reactions as well as how they behave in the stellar surfaces. With CUBES we can finally improve the observations, by covering the crucial blue range in more remote stars and also achieve a higher signal-to-noise ratio (SNR). This is much needed to detect and accurately deblend the absorption lines and in turn derive more accurate and precise abundances of the heavy elements.
↳ astro-ph.SRastro-ph.HEnucl-exnucl-thExper.Astron.(2023)·1 citation
04
Lambda-Nucleon and Sigma-Nucleon potentials from space-time correlation function on the lattice
Hidekatsu Nemura🇯🇵
The hyperon-nucleon interaction with the strangeness $S = - 1$ region is complicated and difficult to investigate because its flavor sector involves all the irreducible representation except the flavor singlet and has the worst signal-to-noise ratio among the strangeness regions. In order to overcome such difficulties the content of this report is twofold: (i) We present an implementation of extended effective baryon block algorithm. This is a straightforward extension of the original which was reported in LATTICE 2013. (ii) We perform single channel analysis for the $Λ N$ system at nearly physical quark masses corresponding to $(m_{π}, m_{K}) \approx (146, 525)$ ~MeV and large volume $(L a)^{4} = (96 a)^{4} \approx$ (8.1 fm) $^{4}$ . Scattering phase shifts for $Λ N$ system are presented.
↳ hep-latnucl-thPoS(2022)·5 citations
05
Production and polarization of $S$ -wave quarkonia in potential nonrelativistic QCD
Nora Brambilla🇩🇪 · Hee Sok Chung🇩🇪 · Antonio Vairo🇩🇪 · Xiang-Peng Wang🇩🇪
Based on the potential nonrelativistic QCD formalism, we compute the nonrelativistic QCD long-distance matrix elements (LDMEs) for inclusive production of $S$ -wave heavy quarkonia. This greatly reduces the number of nonperturbative unknowns and brings in a substantial enhancement in the predictive power of the nonrelativistic QCD factorization formalism. We obtain improved determinations of the LDMEs and find cross sections and polarizations of $J / ψ$ , $ψ (2 S)$ , and excited $Υ$ states that agree well with LHC data. Our results may have important implications in pinning down the heavy quarkonium production mechanism.
↳ hep-phhep-exhep-latnucl-thPRD(2022)·32 citations
06
Masses of vector and pseudovector hybrid mesons in a chiral symmetric model
Walaa I. Eshraim🇦🇪
We enlarge the chiral model, the so-called extended Linear Sigma Model (eLSM), by including the low-lying hybrid nonet with exotic quantum numbers $J^{P C} = 1^{-+}$ and the nonet of their chiral partners with $J^{P C} = 1^{+-}$ to a global $U (3)_{r} \times U (3)_{l}$ chiral symmetry. We use the assignment of the $π_{1}^{h y b} = π_{1} (1600)$ as input to determine the unknown parameters. Then, we compute the lightest vector and pseudovector hybrid masses that could guide ongoing and upcoming experiments in searching for hybrids.
↳ hep-phnucl-thSciPost Phys.Proc.(2022)·2 citations
07
Search for the QCD Critical Point in High Energy Nuclear Collisions
A. Pandav🇮🇳 · D. Mallick🇮🇳 · B. Mohanty🇮🇳
QCD critical point is a landmark region in the QCD phase diagram outlined by temperature as a function of baryon chemical potential. To the right of this second-order phase transition point, one expects first order quark-hadron phase transition boundary, towards the left a crossover region, top of it lies the quark gluon plasma phase and below it the hadronic phase. Hence locating the QCD critical point through relativistic heavy-ion collision experiments is an active area of research. Cumulants of conserved quantities in strong interaction, such as net-baryon, net-charge, and net-strangeness, are suggested to be sensitive to the physics of QCD critical point and are therefore useful observables in the study of the phase transition between quark-gluon plasma and hadronic matter. We review the experimental status of the search for the QCD critical point via the measurements of cumulants of net-particle distributions in heavy ion collisions. We discuss various experimental challenges and associated corrections in such fluctuation measurements. We also comment on the physics implications of the measurements by comparing them with theoretical calculations. This is followed by a discussion on future experiments and measurements related to high baryonic density QCD matter.
↳ nucl-exhep-exnucl-thPPNP(2022)·73 citations
08
Interacting electrons and bosons in the doubly screened $G W$ approximation: A time-linear scaling method for first-principles simulations
Yaroslav Pavlyukh · Enrico Perfetto · Gianluca Stefanucci
We augment the time-linear formulation of the Kadanoff-Baym equations for systems of interacting electrons and quantized phonons or photons with the $G W$ approximation, the Coulomb interaction $W$ being dynamically screened by both electron-hole pairs {\em and} bosonic particles. We also show how to combine different approximations to include simultaneously multiple correlation effects in the dynamics. The final outcome is a versatile framework comprising $2^{12}$ distinct diagrammatic methods, each scaling linearly in time and preserving all fundamental conservation laws. The dramatic improvement over current state-of-the-art approximations brought about by $G W$ is demonstrated in a study of the correlation-induced charge migration of the glycine molecule in an optical cavity.
↳ cond-mat.othercond-mat.mes-hallcond-mat.mtrl-scicond-mat.str-el+1PRB(2022)·3 citations
09
Electric dipole moments and the search for new physics
Ricardo Alarcon · Jim Alexander · Vassilis Anastassopoulos · Takatoshi Aoki · Rick Baartman · Stefan Baeßler · Larry Bartoszek · Douglas H. Beck · Franco Bedeschi · Robert Berger · Martin Berz · Hendrick L. Bethlem and 131 other authors
Static electric dipole moments of nondegenerate systems probe mass scales for physics beyond the Standard Model well beyond those reached directly at high energy colliders. Discrimination between different physics models, however, requires complementary searches in atomic-molecular-and-optical, nuclear and particle physics. In this report, we discuss the current status and prospects in the near future for a compelling suite of such experiments, along with developments needed in the encompassing theoretical framework.
↳ hep-phhep-exhep-latnucl-ex+1140 citations

Affiliations

first authorsco-authorsvia INSPIRE