Nuclear Theory·nucl-th

Friday·October 2, 2020

8 papers—2 primary·6 cross-listed

01
Review of the $Λ$ (1405): A curious case of a strange-ness resonance
Maxim Mai🇺🇸
During its long-lasting history, the $Λ (1405)$ has become a benchmark for our understanding of the $SU (3)$ hadron dynamics. Starting with its theoretical prediction and later experimental verification, until the most recent debates on the existence of the second broad pole, it emerged as a fruitful research area sparking many theoretical and experimental developments. This review intends to provide the reader with the current status of research on the $Λ (1405)$ -resonance, reflecting on historical, experimental and theoretical developments. A common database for experimental results and a comparison of most recent theoretical approaches will be provided in the last two parts of this manuscript.
nucl-thhep-lathep-phnucl-exEur.Phys.J.ST(2021)·107 citations
02
Influence of fast emissions and statistical de-excitation on the isospin transport ratio
A. Camaiani🇮🇹 · S. Piantelli🇮🇹 · A. Ono🇯🇵 · G. Casini🇮🇹 · B. Borderie🇫🇷 · R. Bougault🇫🇷 · C. Ciampi🇮🇹 · J.A. Duenas🇪🇸 · C. Frosin🇮🇹 · J. D. Frankland🇫🇷 · D. Gruyer🇫🇷 · N. LeNeindre🇫🇷 and 9 other authors
Isospin transport ratio is a powerful method to estimate the neutron-proton (n-p) equilibration in heavy-ion collisions, and extensively used to obtain information on the asy-stiffness of the nuclear Equation of State. In fact such a ratio is expected to bypass any perturbations introducing a linear transformation of the chosen observable. In particular, it is supposed to overcome contributions due to emission, either of dynamical or statistical nature, from the primary fragments formed during the collisions. In this paper we explore the validity of this assumption, looking at the quasi-projectile n-p ratio ( $N / Z$ ) in peripheral and semi-peripheral events for Ca+Ca reactions at 35\amev{}, simulated via the Antisymmetrized Molecular Dynamics transport model, coupled to different statistical decay codes. The statistical de-excitation of the primary fragments introduces a linear transformation at relatively high excitation energies (above 2\amev{}) when the residue approaches the Evaporation Attractor Line, while some effect is produced at lower excitation energies due to the occurrence of some non-linearities. As for fast emissions after the end of the projectile-target interaction it is shown that they introduce a non-linear transformation too.
nucl-thnucl-exPRC(2020)·22 citations
03
Effective Field Theory for jet substructure in heavy ion collisions
Varun Vaidya🇺🇸
I develop an Effective Field Theory (EFT) framework to compute jet substructure observables for heavy ion collision experiments. As an illustration, I consider dijet events that accompany the formation of a weakly coupled Quark Gluon Plasma(QGP) medium in a heavy ion collision and look at an observable insensitive to jet selection bias: the simultaneous measurement of jet mass along with the transverse momentum imbalance between the jets that are groomed to remove soft radiation. Treating the jet as an open quantum system, I write down a factorization formula within the SCET(Soft Collinear Effective Theory) framework in the forward scattering regime. The physics of the medium is encoded in a universal soft field correlator while the jet-medium interaction is captured by a medium induced jet function. The factorization formula leads to a Lindblad type equation for the evolution of the reduced density matrix of the jet in the Markovian approximation. The solution for this equation allows a resummation of large logarithms that arise due to the final state measurements imposed while simultaneously summing over multiple incoherent interactions of the jet with the medium.
↳ hep-phhep-thnucl-thJHEP(2021)·34 citations
04
2-group global symmetries, hydrodynamics and holography
Nabil Iqbal🇬🇧 · Napat Poovuttikul🇮🇸
2-group global symmetries are a particular example of how higher-form and conventional global symmetries can fuse together into a larger structure. We construct a theory of hydrodynamics describing the finite-temperature realization of a 2-group global symmetry composed out of $U (1)$ zero-form and $U (1)$ one-form symmetries. We study aspects of the thermodynamics from a Euclidean partition function and derive constitutive relations for ideal hydrodynamics from various points of view. Novel features of the resulting theory include an analogue of the chiral magnetic effect and a chiral sound mode propagating along magnetic field lines. We also discuss a minimalist holographic description of a theory dual to 2-group global symmetry and verify predictions from hydrodynamic descriptions. Along the way we clarify some aspects of symmetry breaking in higher-form theories at finite temperature.
↳ hep-thastro-ph.HEcond-mat.str-elnucl-thSciPost Phys.(2023)·62 citations
05
D-wave effects in heavy quarkonium production in ultraperipheral nuclear collisions
Michal Krelina🇨🇿 · Jan Nemchik🇨🇿
The $D$ -wave admixture in quarkonium wave functions is acquired from the photonlike structure of $V \to Q Q ˉ$ transition in the light-front frame widely used in the literature. Such a $D$ -wave ballast is not justified by any nonrelativistic model for $Q - Q ˉ$ interaction potential and leads to falsified predictions for the cross sections in heavy quarkonium production in ultra-peripheral nuclear collisions. We analyze this negative role of $D$ -wave contribution by comparing with our previous studies based on a simple non-photon-like " $S$ -wave-only" $V \to Q Q ˉ$ transition in the $Q Q ˉ$ rest frame.
↳ hep-phnucl-thPRD(2020)·6 citations
06
Apparent convergence of Padé approximants for the crossover line in finite density QCD
Attila Pásztor🇭🇺 · Zsolt Szép🇭🇺 · Gergely Markó🇩🇪
We propose a novel Bayesian method to analytically continue observables to real baryochemical potential $μ_{B}$ in finite density QCD. Taylor coefficients at $μ_{B} = 0$ and data at imaginary chemical potential $μ_{B}^{I}$ are treated on equal footing. We consider two different constructions for the Padé approximants, the classical multipoint Padé approximation and a mixed approximation that is a slight generalization of a recent idea in Padé approximation theory. Approximants with spurious poles are excluded from the analysis. As an application, we perform a joint analysis of the available continuum extrapolated lattice data for both pseudocritical temperature $T_{c}$ at $μ_{B}^{I}$ from the Wuppertal-Budapest Collaboration and Taylor coefficients $κ_{2}$ and $κ_{4}$ from the HotQCD Collaboration. An apparent convergence of $[p / p]$ and $[p / p + 1]$ sequences of rational functions is observed with increasing $p .$ We present our extrapolation up to $μ_{B} \approx 600$ MeV.
↳ hep-lathep-phnucl-thPRD(2021)·25 citations
07
Confronting lattice parton distributions with global QCD analysis
J. Bringewatt🇺🇸 · N. Sato🇺🇸 · W. Melnitchouk🇺🇸 · Jian-Wei Qiu🇺🇸 · F. Steffens🇩🇪 · M. Constantinou🇺🇸
We present the first Monte Carlo based global QCD analysis of spin-averaged and spin-dependent parton distribution functions (PDFs) that includes nucleon isovector matrix elements in coordinate space from lattice QCD. We investigate the degree of universality of the extracted PDFs when the lattice and experimental data are treated under the same conditions within the Bayesian likelihood analysis. For the unpolarized sector, we find rather weak constraints from the current lattice data on the phenomenological PDFs, and difficulties in describing the lattice matrix elements at large spatial distances. In contrast, for the polarized PDFs we find good agreement between experiment and lattice data, with the latter providing significant constraints on the spin-dependent isovector quark and antiquark distributions.
↳ hep-phhep-latnucl-thPRD(2021)·69 citations
08
Nuclear parton distribution functions with uncertainties in a general mass variable flavor number scheme
Hamzeh Khanpour🇮🇷 · Maryam Soleymaninia🇮🇷 · S. Atashbar Tehrani🇮🇷 · Hubert Spiesberger🇩🇪 · Vadim Guzey🇷🇺
In this article we obtain a new set of nuclear parton distribution functions (nuclear PDFs) at next-to-leading order and next-to-next-to-leading order accuracy in perturbative QCD. The common nuclear deep-inelastic scattering (DIS) data analyzed in our study are complemented by the available charged-current neutrino DIS data with nuclear targets and data from Drell-Yan cross-section measurements for several nuclear targets. In addition, the most recent DIS data from the Jefferson Lab CLAS and Hall C experiments are also added to our data sample. For these specific datasets, we consider the impact of target mass corrections and higher twist effects which are expected to be important in the region of large $x$ and intermediate-to-low $Q^{2}$ . Our analysis is based on a publicly available open-source tool {\tt APFEL}, which has been modified to be applicable for our analysis of nuclear PDFs. Heavy quark contributions to nuclear DIS are considered within the framework of the {\tt FONLL} general-mass variable-flavor-number scheme. The most recent {\tt CT18} PDFs are used as baseline proton PDFs. The uncertainties of nuclear PDFs are determined using the standard Hessian approach. The results of our global QCD analysis are compared with existing nuclear PDF sets and with the fitted cross-sections, for which our set of nuclear PDFs provides a very good description.
↳ hep-phhep-exnucl-thPRD(2021)·50 citations

Affiliations

first authorsco-authorsvia INSPIRE