Nuclear Theory·nucl-th

Monday·September 18, 2023

9 papers—2 primary·7 cross-listed

01
Analysis of the 16C(d,p)17C reaction from microscopic 17C wave functions
Le Hoang Chien · Pierre Descouvemont
We present a semi-microscopic study of the 16C(d,p)17C transfer reaction. The 17C overlap integrals and spectroscopic factors are obtained from a microscopic cluster model, involving many 16C+n configurations. This microscopic model provides a fair description of the 17C bound-state energies. The 16C+d scattering wave functions are defined in the CDCC method, where the deuteron breakup is simulated by pseudostates. The transfer cross sections are in good agreement with recent data. We confirm the 16C(2+)+n structure of the ground state, and show that deuteron breakup effects have a significant influence on the cross sections. We study the 17C(p,d)16C reverse reaction and suggest that the cross section to the 2+ state should be large. A measurement of the ground-state cross section would provide a strong test of the microscopic wave functions.
nucl-th0 citations
02
Evolution of $N = 20, 28, 50$ shell closures in the $20 ⩽ Z ⩽ 30$ region in deformed relativistic Hartree-Bogoliubov theory in continuum
Ru-You Zheng · Xiang-Xiang Sun · Guo-fang Shen · Li-Sheng Geng
Magicity, or shell closure, plays an important role in our understanding of complex nuclear phenomena. In this work, we employ one of the state-of-the-art density functional theories, the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) with the density functional PC-PK1, to investigate the evolution of the $N = 20, 28, 50$ shell closures in the $20 ⩽ Z ⩽ 30$ region. We show how these three conventional shell closures evolve from the proton drip line to the neutron drip line by studying the charge radii, two-neutron separation energies, two-neutron gaps, quadrupole deformations, and single-particle levels. In particular, we find that in the $21 ⩽ Z ⩽ 27$ region, the $N = 50$ shell closure disappears or becomes quenched, mainly due to the deformation effects. Similarly, both experimental data and theoretical predictions indicate that the $N = 28$ shell closure disappears in the Mn isotopic chain, also predominantly due to the deformation effects. The DRHBc theory predicts the existence of the $N = 20$ shell closure in the Ca, Sc, and Ti isotopic chains, but the existing data for the Ti isotopes suggests the contrary, and therefore more investigations are needed.
nucl-thnucl-exCPC(2024)·15 citations
03
Emergent nucleosynthesis from a 1.2 second long simulation of a black-hole accretion disk
T. M. Sprouse · K. A. Lund · J. M. Miller · G. C. McLaughlin · M. R. Mumpower
We simulate a black-hole accretion disk system with full-transport general relativistic neutrino radiation magnetohydrodynamics (GR $ν$ RMHD) for 1.2 seconds. This system is likely to form after the merger of two compact objects and is thought to be a robust site of $r$ -process nucleosynthesis. We consider the case of a black-hole accretion disk arising from the merger of two neutron stars. Our simulation time coincides with the nucleosynthesis timescale of the $r$ process ( $\sim$ 1 second). Because these simulations are time consuming, it is common practice to run for `short' duration of approximately 0.1 to 0.3 seconds. We analyze the nucleosynthetic outflow from this system and compare the results between stopping at 0.12 and 1.2 seconds respectively. We find that the addition of mass ejected in the longer simulation as well as more favorable thermodynamic conditions from emergent viscous ejecta greatly impacts the nucleosynthetic outcome. We quantify the error in nucleosynthetic outcomes between short and long cuts.
↳ astro-ph.HEastro-ph.SRgr-qcnucl-thApJ(2024)·22 citations
04
Adiabatic Quantum Computation with the Fermionic Position Space Schrödinger Equation
Kenneth S. McElvain🇺🇸
The efficient encoding of the fermionic Schrödinger equation as a spin system Hamiltonian is a long-term problem. I describe an encoding for the fermionic position space Schrödinger equation on a finite-volume periodic lattice with a local potential. The challenging part of the construction is the implementation of the kinetic energy operator, which is essentially the Laplacian. The finite difference implementation on the lattice combines contributions from neighboring lattice sites, which is complicated by fermionic exchange symmetry. Two independently useful techniques developed here are operator filtering and entanglement gadgets. Operator filtering is useful when a simple operator acting on a subspace of the full Hilbert space has a desired set of interactions. Occupation suppression of the complement of the subspace then filters away unwanted contributions of the operator. Entanglement gadgets encode the same information differently in two sets of qubits. We may then independently choose the most efficient encoding for operators acting on the qubits. The construction for the Laplacian described here has $O (A n 2^{D})$ cost in bounded Pauli weight terms where $A$ is the number of identical spinless fermions, $N = 2^{n}$ is the number of lattice points in each direction, and $D$ is the number of dimensions. The finite volume context protects the gap between the ground state and the first excited state, yielding polynomial time complexity with the box size.
↳ quant-phnucl-th0 citations
05
Chemical potential (in)dependence of hadron scatterings in the hadronic phase of QCD-like theories and its applications
Kotaro Murakami🇯🇵 · Etsuko Itou🇯🇵 · Kei Iida🇯🇵
We formulate a method for calculating the hadron-hadron scattering amplitudes at nonzero chemical potential ( $μ$ ) in the hadronic phase at zero temperature, where the baryon number symmetry remains to be violated. Although it is widely believed that the physical quantities do not change even if we turn on a small $μ$ at zero temperature, the shape of correlation functions for a single hadron depends on $μ$ . Then, the dispersion relation of the single hadron is modified to $E (p, μ) = p^{2} + m^{2} - μ n_{O}$ . Here, $m$ and $n_{O}$ denote the hadron mass at $μ = 0$ and the quantum number, respectively. From this relation, it is possible that the effective mass of the hadron depends on $μ$ . We extend the HAL QCD method at $μ = 0$ to the case of $μ \neq = 0$ , which allows us to extract the scattering phase shifts via the interaction potential. We have found that the interaction potential can depend on $μ$ only through the effective mass while the scattering phase shifts, obtained by solving the Schrödinger equation with the interaction potential, are independent of $μ$ . We also numerically analyze the S-wave scatterings of two pions with isospin $I = 2$ and two scalar diquarks within the framework of QC $_{2}$ D at nonzero quark chemical potential. While the lattice is not exactly set to zero temperature, the $μ$ -independence can be observed. Furthermore, we improve the results for the S-wave scatterings of two hadrons obtained above by taking the $μ$ -independence for granted. Thanks to the asymmetric property of the correlation functions for diquarks at $μ \neq = 0$ , we can access a long- $τ$ regime and can reduce the systematic error coming from inelastic contributions.
↳ hep-lathep-phnucl-thJHEP(2024)·8 citations
06
Exploring jet transport coefficients by elastic and radiative scatterings in the strongly interacting quark-gluon plasma
Ilia Grishmanovskii🇩🇪 · Taesoo Song🇩🇪 · Olga Soloveva🇩🇪 · Carsten Greiner🇩🇪 · Elena Bratkovskaya🇩🇪
We investigate the interaction of leading jet partons within a strongly interacting quark-gluon plasma (sQGP) medium, using the effective dynamical quasiparticle model (DQPM). The DQPM offers a description of the sQGP's non-perturbative nature at finite temperature $T$ and baryon chemical potential $μ_{B}$ through a propagator representation of massive off-shell partons (quarks and gluons). These partons are characterized by spectral functions with $T, μ_{B}$ dependent masses and widths, adjusted to reproduce the lattice Quantum Chromodynamics (lQCD) equation-of-state (EoS) for the QGP in thermodynamic equilibrium. Our focus lies on examining the jet transport coefficients by elastic scattering in sQGP, specifically the transverse momentum transfer squared per unit length denoted as $q^$ , within the QGP. Furthermore, we investigate the dependence of these coefficients on both the medium temperature $T$ and the jet parton energy. By studying the jet transport coefficients and their relationship to temperature and parton energy, we aim to gain insights into the dynamics of jet propagation in the strongly interacting quark-gluon plasma medium.
↳ hep-phnucl-thPoS(2024)·1 citation
07
Investigating radial flow-like effects via pseudorapidity and transverse spherocity dependence of particle production in pp collisions at the LHC
Aswathy Menon Kavumpadikkal Radhakrishnan🇮🇳 · Suraj Prasad🇮🇳 · Sushanta Tripathy🇨🇭 · Neelkamal Mallick🇮🇳 · Raghunath Sahoo🇮🇳
Recent observations of quark-gluon plasma (QGP) like signatures in high multiplicity proton-proton (pp) collisions, have compelled the heavy-ion physics community to re-examine small collision systems for proper baseline studies. Event-shape-based studies in pp collisions have succeeded to a certain extent in identifying the rare events mimicking such heavy-ion-like behaviour. In this study, we incorporate PYTHIA8 and AMPT to study radial flow-like signatures in pp collisions at $s = 13$ TeV as a function of transverse spherocity and pseudorapidity. The selection of softer events possibly carrying heavy-ion-like features is performed using the transverse spherocity event-shape observable. As the particle production mechanism in midrapidity differs greatly from the forward rapidity, a pseudorapidity-dependent study is meaningful. Keeping ALICE 3 upgrades at the LHC in mind, this study aims to demonstrate the transverse spherocity and pseudorapidity dependence of the mean transverse momentum, particle ratios, and kinetic freezeout parameters in pp collisions at $s$ = 13 TeV using PYTHIA8. We observe that the isotropic events show enhanced radial-flow effects in all multiplicity classes, however, the jetty events show signatures of the radial flow-like effects only in high-multiplicity events. For the first time, we show the transverse spherocity and pseudorapidity dependence of partonic modification factor in pp collisions, which clearly shows that by choosing transverse spherocity, one can directly probe the radial flow-like effects in pp collisions at the LHC.
↳ hep-phhep-exnucl-exnucl-thEur.Phys.J.Plus(2025)·8 citations
08
Thermoelectric response of a hot and weakly magnetized anisotropic QCD medium
Salman Ahamad Khan🇮🇳 · Debarshi Dey🇮🇳 · Binoy krishna Patra🇮🇳
We have studied the Seebeck and Nernst coefficients of a weakly magnetized hot QCD medium having a weak momentum anisotropy within the kinetic theory approach. The thermal medium effects have been incorporated in the framework of a quasi-particle model where the medium dependent mass of the quark has been calculated using perturbative thermal QCD in the presence of a weak magnetic field which leads to different masses for the left ( $L$ ) and right ( $R$ ) handed chiral quark modes. We have found that the Seebeck and Nernst coefficient magnitudes for the individual quark flavors as well as for the composite medium are decreasing functions of temperature and decreasing functions of anisotropy strength. The Nernst coefficient magnitudes are about an order of magnitude smaller than their Seebeck counterparts, indicating the Seebeck effect constitutes a stronger response than the Nernst effect. The average percentage change corresponding to switching between quasiparticle modes ( $L \to R$ or $R \to L$ ) is an order of magnitude smaller for Nernst coefficients, compared to the Seebeck coefficients.
↳ hep-phnucl-thPRC(2024)·5 citations
09
Non-equilibrium effects on stability of hybrid stars with first-order phase transitions
Peter B. Rau · Gabriela G. Salaben
The stability of hybrid stars with first-order phase transitions as determined by calculating fundamental radial oscillation modes is known to differ from the predictions of the widely-used Bardeen--Thorne--Meltzer criterion. We consider the effects of out-of-chemical-equilibrium physics on the radial modes and hence stability of these objects. For a barotropic equation of state, this is done by allowing the adiabatic sound speed to differ from the equilibrium sound speed. We show that doing so extends the stable branches of stellar models, allowing stars with rapid phase transitions to support stable higher-order stellar multiplets similarly to stars with multiple slow phase transitions. We also derive a new junction condition to impose on the oscillation modes at the phase transition. Termed the reactive condition, it is physically motivated, consistent with the generalized junction conditions between two phases, and has the common rapid and slow conditions as limiting cases. Unlike the two common cases, it can only be applied to nonbarotropic stars. We apply this junction condition to hybrid stellar models generated using a two-phase equation of state consisting of nuclear matter with unpaired quark matter at high densities joined by a first-order phase transition and show that like in the slow limiting case, stars that are classically unstable are stabilized by a finite chemical reaction speed.
↳ astro-ph.HEnucl-thPRD(2023)·15 citations

Affiliations

first authorsco-authorsvia INSPIRE