Nuclear Theory·nucl-th

Tuesday·May 23, 2023

13 papers—5 primary·8 cross-listed

01
Modified approach for accounting for dissipation in theoretical description of fusion of complex nuclei
I. I. Gontchar · M. V. Chushnyakova
The process of fusion of complex nuclei is of significant interest as an example of the collective nuclear motion of large amplitude as well as a route for synthesis of new superheavy chemical elements. This process is accompanied by the dissipation of the energy of collective motion, at least at the last stage. The dissipative nature of fusion is accounted for in many theoretical approaches. In the present work, we propose a modified method for accounting for dissipation. The main idea is to use the superfluid model for evaluating nuclear temperature, not the Fermi-gas model like in previous approaches. The calculations of the fusion (capture) cross sections are performed for reaction 16O+92Zr at the collision energies ranging from 46 up to 70 MeV. For this reaction and at these conditions it turns out, that the more complicated superfluid model results in the cross sections which are indistinguishable from the ones obtained using the much simpler Fermi-gas model.
nucl-th1 citation
02
Charge radii of atomic nuclei and shell effects
M. V. Chushnyakova · I. I. Gontchar · E. V. Kulik
In the present work, we study the experimental data on the root mean square charge radii of the spherical atomic nuclei. The purpose of this analysis is to clarify what is the manifestation of the neutron shells in the considered observable and to find regularities in the behavior of the charge radii when a shell neutron is crossed. As the result, we have found manifestations of the shells N_sh=8,28,50 and 82. It turns out that the well-known shells with the neutron numbers 20 and 126 do not show up. The present analysis is performed by means of the relative charge radius x(N,N_sh,Z). This value is equal to the charge radius of a given isotope over the charge radius of the isotope of the given element with the closed neutron shell. It is shown that the values of x form groups corresponding to different values of N_sh. Prediction for unknown charge radius of sulfur-30 has been made.
nucl-th0 citations
03
Singlet cross section and the tensor interaction in $p p \to Λ ˉ Λ$
Deepak Pachattu
In this short paper, we demonstrate using irreducible tensorial techniques and in a model-independent way, why tensor interactions and also orbital-angular momentum-changing vector interactions are absent in the singlet unpolarized differential cross section for the reaction $p p \to Λ ˉ Λ$ .
nucl-thhep-exnucl-ex0 citations
04
On the screening condition in the core of neutron stars
Dmitry Kobyakov
Earlier, the screening condition in neutron star core has been formulated as equality of velocities of superconducting protons and the electrons $v_{p} = u_{e}$ at wavenumbers $q ≪ λ^{- 1}$ ( $λ$ is the London penetration depth) and has been used to derive the force exerted by the electrons on a moving flux tube. By calculating the current-current response, I find that $v_{p} \neq = u_{e}$ for $l^{- 1} < q ≪ λ^{- 1}$ ( $l$ is the electron mean free path). I show that at typical realistic parameters the electric field induced by a moving (relative to the electrons) flux tube is not screened by the electron currents. The implication is that the existing picture of the momentum exchange between the electrons and the flux tubes must be reassessed.
nucl-thastro-ph.HEastro-ph.SRcond-mat.supr-conPRC(2023)·2 citations
05
Study of np-scattering for S, P and D Waves using Deng-Fan Potential by Phase Function Method
Ayushi Awasthi · O.S.K.S Sastri
In this paper, the np - scattering phase shifts and cross section for S,P and D partial waves have been obtained for energies below the pion threshold, by considering Deng-Fan potential as model of interaction. The radial time independent Schrödinger equation has been analytically solved using Nikiforov - Uvarov method to obtain the energy expression for ground state of np system. Utilising this, the scattering phase shifts for $^{3} S_{1}$ have been obtained using phase function method. The phase equations for various scattering states $^{1} S_{0}$ , $^{1} P_{1}$ , $^{3} P_{0, 1, 2}$ , $^{1} D_{2}$ , and $^{3} D_{1, 2, 3}$ have been numerically solved for obtaining corresponding scattering phase shifts and their respective partial cross section. The total scattering cross sections computed at various energies are found to be closely matching with experimental data. The low energy scattering parameters determined from scattering phase shifts of $^{3} S_{1}$ and $^{1} S_{0}$ are reasonably close to experimental ones. Hence, Deng-Fan potential is a good phenomenological potential to understand the np - scattering system.
nucl-th0 citations
06
Quantum Simulations of SO(5) Many-Fermion Systems using Qudits
Marc Illa🇺🇸 · Caroline E. P. Robin🇩🇪 · Martin J. Savage🇺🇸
The structure and dynamics of quantum many-body systems are the result of a delicate interplay between underlying interactions, which leads to intricate entanglement structures. Despite this apparent complexity, symmetries emerge and have long been used to determine the relevant degrees of freedom and simplify classical descriptions of these systems. In this work, we explore the potential utility of quantum computers with arrays of qudits in simulating interacting fermionic systems, when the qudits can naturally map these relevant degrees of freedom. The Agassi model of fermions is based on an underlying $so (5)$ algebra, and the systems it describes can be partitioned into pairs of modes with five basis states, which naturally embed in arrays of $d = 5$ qudits (qu5its). Classical noiseless simulations of the time evolution of systems of fermions embedded in up to twelve qu5its are performed using Google's cirq software. The resource requirements of the qu5it circuits are analyzed and compared with two different mappings to qubit systems, a physics-aware Jordan-Wigner mapping and a state-to-state mapping. We find advantages in using qudits, specifically in lowering the required quantum resources and reducing anticipated errors that take the simulation out of the physical space. A previously unrecognized sign problem has been identified from Trotterization errors in time evolving high-energy excitations. This has implications for quantum simulations in high-energy and nuclear physics, specifically of fragmentation and highly inelastic, multi-channel processes.
↳ quant-phhep-phnucl-thPRC(2023)·25 citations
07
Number density interpretation of dihadron fragmentation functions
D. Pitonyak🇺🇸 · C. Cocuzza🇺🇸 · A. Metz🇺🇸 · A. Prokudin🇺🇸 · N. Sato🇺🇸
We present a new quantum field-theoretic definition of fully unintegrated dihadron fragmentation functions (DiFFs) as well as a generalized version for $n$ -hadron fragmentation functions. We demonstrate that this definition allows certain sum rules to be satisfied, making it consistent with a number density interpretation. Moreover, we show how our corresponding so-called extended DiFFs that enter existing phenomenological studies are number densities and also derive their evolution equations. Within this new framework, DiFFs extracted from experimental measurements will have a clear physical meaning.
↳ hep-phhep-exnucl-thPRL(2024)·38 citations
08
Electric current from Schwinger's time-ordered propagator
Cristian Villavicencio🇨🇱
The quasistatic electric current density of fermions in the presence of an external electric field is determined through the utilization of a time-ordered Schwinger propagator. The study encompasses the necessary conditions for establishing a well-defined time-ordered propagator within the Schwinger formalism, specifically concentrating on constant and uniform electromagnetic fields. Within this theoretical framework, a chemical potential is introduced, resulting in non-zero values for the electric current and charge number density. Consequently, the dependence of electric conductivity on the strength of the electric field and the charge number density is investigated.
↳ hep-phnucl-thRev.Mex.Fis.(2026)·1 citation
09
On the momentum broadening of in-medium jet evolution using a light-front Hamiltonian approach
Meijian Li🇫🇮 · Tuomas Lappi🇫🇮 · Xingbo Zhao🇨🇳 · Carlos A. Salgado🇪🇸
Following the non-perturbative light-front Hamiltonian formalism developed in our preceding work [Phys.Rev.D 104 (2021) 5, 056014], we investigate the momentum broadening of a quark jet inside a SU(3) colored medium. We perform the numerical simulation of the real-time jet evolution in Fock spaces of a single quark, a quark-gluon state, and coupled quark- and quark-gluon states at various jet momenta $p^{+}$ and medium densities. With the obtained jet light-front wavefunction, we extract the jet transverse momentum distribution, the quenching parameter, and the gluon emission rate. We analyze the dependence of momentum broadening on $p^{+}$ , medium density, color configuration, spatial correlation, and medium-induced gluon emission. For comparison, we also derive analytically the expectation value of the transverse momentum of a quark-gluon state in any color configuration and in an arbitrary spatial distribution in the eikonal limit. This work can help understand jet momentum broadening in the non-eikonal regime.
↳ hep-phnucl-thPRD(2023)·21 citations
10
Exploring the $0^{-}$ bound state with dressed quarks in Minkowski space
A. Castro · W. de Paula · E. Ydrefors · T. Frederico · G. Salme
The Bethe-Salpeter equation for a pseudoscalar bound-system, with i) a ladder kernel with massive gluons, ii) dynamically-dressed quark mass function and iii) an extended quark-gluon vertex, is solved in Minkowski space by using the Nakanishi integral representation of the Bethe-Salpeter amplitude. The quark dressing is implemented through a phenomenological ansatz, which was tuned by lattice QCD calculations of the quark running mass. The latter were also used for assigning the range of the gluon mass and the parameter featuring the extended color density. This framework allows to investigate the gluon dynamics that manifest itself in the quark dressing, quark-gluon vertex and the binding, directly in the physical space. We present the first results for low-density pseudoscalar systems in order to elucidate the onset of the interplay between the above mentioned gluonic phenomena, and we discuss both static and dynamical quantities, like valence longitudinal and transverse distributions.
↳ hep-phhep-thnucl-thPLB(2023)·9 citations
11
Production of bottomonia states in proton+proton and heavy-ion collisions
Vineet Kumar🇮🇳 · Prashant Shukla🇮🇳 · Abhijit Bhattacharyya🇮🇳
In this work, we review the experimental and theoretical developments of bottomonia production in proton+proton and heavy-ion collisions. The bottomonia production process is proving to be one of the most robust processes to investigate the fundamental aspects of Quantum Chromodynamics at both low and high temperatures. The LHC experiments in the last decade have produced large statistics of bottomonia states in wide kinematic ranges in various collision systems. The bottomonia have three $Υ$ S-states which are reconstructed in dilepton invariant mass channel with high mass resolution by LHC detectors and P-states are measured via their decay to S-states. We start with the details of measurements in proton+proton collisions and their understanding in terms of various effective theoretical models. Here we cover both the Tevatron and LHC measurements with $s$ spanning from 1.8 TeV to 13 TeV. The bottomonia states have particularly been very good probes to understand strongly interacting matter produced in heavy-ion collisions. The Pb+Pb collisions have been performed at $s_{N N}$ = 2.76 TeV and 5.02 TeV at LHC. This led to the detailed study of the modification of bottomonia yields as a function of various observables and collision energy. At the same time, the improved results of bottomonia production became available from RHIC experiments which have proven to be useful for a quantitative comparison. A systematic study of bottomonia production in p+p, p+Pb and Pb+Pb has been very useful to understand the medium effects in these collision systems. We review some of the (if not all the) models of bottomonia evolution due to various processes in a large dynamically evolving medium and discuss these in comparison with the measurements.
↳ hep-phnucl-exnucl-thPPNP(2023)·3 citations
12
Inconsistencies in, and short pathlength correction to, $R_{AA} (p_{T})$ in $A + A$ and $p + A$ collisions
Coleridge Faraday🇿🇦 · Antonia Grindrod🇿🇦 · W. A. Horowitz🇿🇦
We present the first leading hadron suppression predictions in $Pb + Pb$ and $p + Pb$ collisions from a convolved radiative and collisional energy loss model in which partons propagate through a realistic background and in which the inelastic energy loss receives a short pathlength correction. We find that the short pathlength correction is small for $D$ and $B$ meson $R_{AA} (p_{T})$ in both $Pb + Pb$ and $p + Pb$ collisions. However the short pathlength correction leads to a surprisingly large reduction in suppression for $π$ mesons in $p + Pb$ and even $Pb + Pb$ collisions. We systematically check the consistency of the assumptions used in the radiative energy loss derivation - such as collinearity, softness, and large formation time - with the final numerical model. While collinearity and softness are self-consistently satisfied in the final numerics, we find that the large formation time approximation breaks down at modest to high momenta $p_{T} ≳ 30$ GeV. We find that both the size of the small pathlength correction to $R_{AA} (p_{T})$ and the $p_{T}$ at which the large formation time assumption breaks down are acutely sensitive to the chosen distribution of scattering centers in the plasma.
↳ hep-phnucl-thEPJC(2023)·16 citations
13
Conserved charge susceptibilities in the relativistic mean-field hadron resonance gas model: constraints on hadronic repulsive interactions
Somenath Pal🇮🇳 · Guruprasad Kadam🇮🇳 · Abhijit Bhattacharyya🇮🇳
We investigate the effect of repulsive interaction between hadrons on the susceptibilities of conserved charges, namely baryon number (B), electric charge (Q) and strangeness (S). We estimate second fourth and sixth-order susceptibilities of conserved charges, their differences, ratios, and correlations within the ambit of the mean-field hadron resonance gas (MFHRG) model. We consider repulsive mean-field interaction among meson pairs, baryon pairs and anti-baryon pairs separately and constrain them by confronting the results of various susceptibilities with the recent lattice QCD (LQCD) data. We find that the repulsive interactions between baryon-baryon pairs and antibaryon-antibaryon pairs are sufficient to describe the baryon susceptibilities of hadronic matter at temperatures below the QCD transition temperature. However, small but finite mesonic repulsive interaction is needed to describe electric charge and strangeness susceptibilities. We finally conclude that the repulsive interaction between hadrons plays a very important role in describing the thermodynamic properties of hadronic matter, especially near the quark-hadron phase transition temperature ( $T_{c}$ ). The mean-field parameter for baryons ( $K_{B}$ ) should be constrained in the range $0.40 \leq K_{B} \leq 0.450$ $GeV.fm^{3}$ to get a good agreement of baryon susceptibilities with the LQCD results, whereas meson mean-field parameter $K_{M} \sim 0.05$ $GeV.fm^{3}$ must be included with $K_{B}$ to get a reasonable agreement of the MFHRG model with the LQCD results for electric charge and strangeness susceptibilities.
↳ hep-phnucl-thMod.Phys.Lett.A(2025)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE