Nuclear Theory·nucl-th

Friday·May 28, 2021

8 papers—4 primary·4 cross-listed

01
Predictions for flow harmonic distributions and flow factorization ratios at RHIC
Leonardo Barbosa🇧🇷 · Fernando G. Gardim🇧🇷 · Frédérique Grassi🇧🇷 · Pedro Ishida🇧🇷 · Matthew Luzum🇧🇷 · Meera V. Machado🇩🇰 · Jacquelyn Noronha-Hostler🇺🇸
Data obtained at RHIC can be reproduced with relativistic viscous hydrodynamic simulations by adjusting the viscosity and initial conditions but it is difficult to disentangle these quantities. It is therefore important to find orthogonal observables to constrain the initial conditions separately from the viscosity. New observables have been measured at the LHC and shown to be sensitive to initial conditions and less to medium properties, specifically factorization breaking ratios appears to be promising. Here we consider two initial condition models, NeXus and TRENTO. While both models yield similar results for the scaled flow harmonic distributions both at the LHC and RHIC, they lead to quantitatively much more different patterns for the factorization breaking ratios at RHIC than at LHC, due to the shorter lifetime. Additionally, not only final state interactions but also initial free streaming matter in these ratio predictions and differences between these are enhanced at RHIC compared to LHC. Therefore experimental factorization breaking ratios at RHIC top energy (for transverse momentum) would be interesting to get.
nucl-thnucl-ex13 citations
02
Nuclear superfluidity at finite temperature
Elena Litvinova🇺🇸 · Peter Schuck🇫🇷
The equation of motion for the two-fermion two-time correlation function in the pairing channel is considered at finite temperature. Within the Matsubara formalism, the Dyson-type Bethe-Salpeter equation (Dyson-BSE) with the frequency-dependent interaction kernel is obtained. Similarly to the case of zero temperature, it is decomposed into the static and dynamical components, where the former is given by the contraction of the bare interaction with the two-fermion density and the latter is represented by the double contraction of the four-fermion two-time correlation function, or propagator, with two interaction matrix elements. The dynamical kernel with the four-body propagator, being formally exact, requires approximations to avoid generating prohibitively complicated hierarchy of equations. We focus on the approximation where the dynamical interaction kernel is truncated on the level of two-body correlation functions, neglecting the irreducible three-body and higher-rank correlations. Such a truncation leads to the dynamical kernel with the coupling between correlated fermionic pairs, which can be interpreted as emergent bosonic quasibound states, or phonons, of normal and superfluid nature. The latter ones are, thus, the mediators of the dynamical superfluid pairing. In this framework, we obtained the closed system of equations for the fermionic particle-hole and particle-particle propagators. This allows us to study the temperature dependence of the pairing gap beyond the Bardeen-Cooper-Schrieffer approximation, that is implemented for medium-heavy nuclear systems. The cases of 68Ni and 44,46Ca are discussed in detail.
nucl-thcond-mat.supr-conPRC(2021)·12 citations
03
Benchmarking Many-body Approaches for the Determination of Isotope Shift Constants: Application to the Li, Be $^{+}$ and Ar $^{15 +}$ Isoelectronic Systems
B. K. Sahoo · B. Ohayon
We have applied relativistic coupled-cluster (RCC) theory to determine the isotope shift (IS) constants of the first eight low-lying states of the Li, Be $^{+}$ and Ar $^{15 +}$ isoelectronic systems. Though the RCC theory with singles, doubles and triples approximation (RCCSDT method) is an exact method for these systems for a given set of basis functions, we notice large differences in the results from this method when various procedures in the RCC theory framework are adopted to estimate the IS constants. This has been demonstrated by presenting the IS constants of the aforementioned states from the finite-field, expectation value and analytical response (AR) approaches of the RCCSDT method. Contributions from valence triple excitations, Breit interaction and lower-order QED effects to the evaluation of these IS constants are also highlighted. Our results are compared with high-precision calculations reported using few-body methods wherever possible. We find that results from the AR procedure are more reliable than the other two approaches. This analysis is crucial for understanding the roles of electron correlation effects in the accurate determination of IS constants in the heavier atomic systems, where few-body methods cannot be applied.
nucl-thphysics.atom-phphysics.comp-phPRA(2021)·10 citations
04
Correlations between nuclear landscape boundaries and neutron-rich r-process abundances
Q.Z. Chai · Y. Qiang · J.C. Pei
Motivated by the newly observed $^{39}$ Na in experiments, systematic calculations of global nuclear binding energies with seven Skyrme forces are performed. We demonstrate the strong correlation between the two-neutron separation energies ( $S_{2 n}$ ) of $^{39}$ Na and the total number of bound nuclei of the whole nuclear landscape. Furthermore, with calculated nuclear masses, we perform astrophysical rapid-neutron capture process ( $r$ -process) simulations by using nuclear reaction code TALYS and nuclear reaction network code SkyNet. $r$ -process abundances from ejecta of neutron star mergers and core-collapse supernova are compared. Prominent covariance correlations between nuclear landscape boundaries and neutron-rich $r$ -process abundances before the third peak are shown. This study highlights the needs for further experimental studies of drip-line nuclei around $^{39}$ Na for better constraints on nuclear landscape boundaries and $r$ -process.
nucl-thPRC(2022)·12 citations
05
Qudit circuits with SU(d) symmetry: Locality imposes additional conservation laws
Iman Marvian🇺🇸 · Hanqing Liu🇺🇸 · Austin Hulse🇺🇸
Local symmetric quantum circuits provide a simple framework to study the dynamics and phases of complex quantum systems with conserved charges. However, some of their basic properties have not yet been understood. Recently, it has been shown that such quantum circuits only generate a restricted subset of symmetric unitary transformations [I. Marvian, Nature Physics, 2022]. In this paper, we consider circuits with 2-local SU(d)-invariant unitaries acting on qudits, i.e., d-dimensional quantum systems. Our results reveal a significant distinction between the cases of d = 2 and d>2. For qubits with SU(2) symmetry, arbitrary global rotationally-invariant unitaries can be generated with 2-local ones, up to relative phases between the subspaces corresponding to inequivalent irreducible representations (irreps) of the symmetry, i.e., sectors with different angular momenta. On the other hand, for d>2, in addition to similar constraints on the relative phases between the irreps, locality also restricts the generated unitaries inside these conserved subspaces. These constraints impose conservation laws that hold for dynamics under 2-local SU(d)-invariant unitaries, but are violated under general SU(d)-invariant unitaries. Based on this result, we show that the distribution of unitaries generated by random 2-local SU(d)-invariant unitaries does not converge to the Haar measure over the group of all SU(d)-invariant unitaries, and in fact, for d>2, is not even a 2-design for the Haar distribution.
↳ quant-phcond-mat.str-elhep-thmath-ph+228 citations
06
Case for quarkyoniclike matter from a constituent quark model
Aaron Park🇰🇷 · Kie Sang Jeong🇺🇸 · Su Houng Lee🇰🇷
Based on the fact that the constituent quark model reproduces the recent lattice result on baryon-baryon repulsion at short distance and that it includes the quark dynamics with confinement, we analyze to what extent the quarkyonic modes appear in the phase space of baryons as one increases the density before only quark dynamics and hence deconfinement occurs. We find that as one increases the baryon density, the initial quark mode that appears will involve the $d (u)$ -quark from a neutron (proton), which will leave the most attractive ( $u d$ ) diquark intact.
↳ hep-phnucl-thPRD(2021)·11 citations
07
Effect of non-uniform efficiency on higher-order cumulants in heavy-ion collisions
Fan Si🇨🇳 · Yifei Zhang🇨🇳 · Xiaofeng Luo🇨🇳
We perform a systematic study on the effect of non-uniform track efficiency correction in higher-order cumulant analysis in heavy-ion collisions. Through analytical derivation, we find that the true values of cumulants can be successfully reproduced by the efficiency correction with an average of the realistic detector efficiency for particles with the same charges within each single phase space. The theoretical conclusions are supported by a toy model simulation by tuning the non-uniformity of the efficiency employed in the track-by-track efficiency correction method. The valid averaged efficiency is found to suppress the statistical uncertainties of the reproduced cumulants dramatically. Thus, usage of the averaged efficiency requires a careful study of phase space dependence. This study is important for carrying out precision measurements of higher-order cumulants in heavy-ion collision experiments at present and in future.
↳ physics.data-annucl-exnucl-thCPC(2021)·1 citation
08
Neutron star asteroseismology and nuclear saturation parameter
Hajime Sotani
Adopting various unified equations of state (EOSs), we examine the quasinormal modes of gravitational waves from cold neutron stars. We focus on the fundamental ( $f$ -), 1st pressure ( $p_{1}$ -), and 1st spacetime ( $w_{1}$ -) modes, and derive the empirical formulae for the frequencies and damping rate of those modes. With the resultant empirical formulae, we find that the value of $η$ , which is a specific combination of the nuclear saturation parameters, can be estimated within $\sim 30%$ accuracy, if the $f$ -mode frequency from the neutron star whose mass is known would be observed or if the $f$ - and $p_{1}$ -mode frequencies would be simultaneously observed, even though this estimation is applicable only for the low-mass neutron stars. Additionally, we find that the mass and radius of canonical neutron stars can be estimated within a few per cent accuracy via the simultaneous observations of the $f$ - and $w_{1}$ -mode frequencies. We also find that, if the $f$ -, $p_{1}$ -, and $w_{1}$ -mode frequencies would be simultaneously observed, the mass of canonical neutron stars can be estimated within $2%$ accuracy, while the radius can be estimated within $1%$ for the neutron star with $M \geq 1.6 M_{⊙}$ or within $0.6%$ for the neutron star with $M \geq 1.4 M_{⊙}$ constructed with the EOS constrained via the GW170817 event. Furthermore, we find the strong correlation between the maximum $f$ -mode frequency and the neutron star radius with the maximum mass, between the minimum $w_{1}$ -mode frequency and the maximum mass, and between the minimum damping rate of the $w_{1}$ -mode and the stellar compactness for the neutron star with the maximum mass.
↳ astro-ph.HEnucl-thPRD(2021)·34 citations

Affiliations

first authorsco-authorsvia INSPIRE