Nuclear Theory·nucl-th

Tuesday·July 12, 2022

13 papers—6 primary·7 cross-listed

01
Critical lensing and kurtosis near a critical point in the QCD phase diagram in and out-of-equilibrium
Travis Dore🇺🇸 · Jamie M. Karthein🇺🇸 · Isaac Long🇺🇸 · Debora Mroczek🇺🇸 · Jacquelyn Noronha-Hostler🇺🇸 · Paolo Parotto🇺🇸 · Claudia Ratti🇺🇸 · Yukari Yamauchi🇺🇸
In this work, we study the lensing effect of the QCD critical point on hydrodynamic trajectories, and its consequences on the net-proton kurtosis $κ_{4}$ . Including critical behavior by means of the BEST Collaboration equation of state (EoS), we first consider a scenario in equilibrium, then compare with hydrodynamic 0+1D simulations with Bjorken expansion, including both shear and bulk viscous terms. We find that, both in and out-of-equilibrium, the size and shape of the critical region directly affect if the signal will survive through the dynamical evolution.
nucl-thhep-exhep-phPRD(2022)·43 citations
02
Renormalization of proton-proton fusion in chiral effective field theory
Tai-Xing Liu🇨🇳 · Rui Peng🇨🇳 · Songlin Lyu🇨🇳 · Bingwei Long🇨🇳
Renormalization of proton-proton fusion is studied in the framework of chiral effective field theory. Strict perturbative treatment of subleading corrections is applied in the analysis. Possible enhancement of two-nucleon contact axial current operators is the focus of the study. We find evidence that supports a previous proposal in the literature to promote one of the contact axial current operators.
nucl-thPRC(2022)·7 citations
03
Measuring differential flow angle fluctuations in relativistic nuclear collisions
Niseem Magdy🇺🇸
Recently studies of the differential nature of the flow angle fluctuations, known as event plane angular decorrelation, indicated that measurements that assume a common symmetry plane may need to consider the flow angle fluctuations effect. Using the HIJING and AMPT models, it is shown that the flow angle fluctuations measurements, obtained with the two- and three-subevents correlation method, could have significant non-flow effects associated with long- and short-range non-flow correlations. The current study demonstrates the four-subevents cumulant methods' ability to reduce the non-flow effects. It is further argued that the measurements using the four-subevents correlation method can be used to provide accurate quantification of the differential flow angle fluctuations.
nucl-thhep-exhep-phnucl-exPRC(2022)·10 citations
04
$^{7}$ H ground state as a $^{3}$ H+4n resonance
Emiko Hiyama🇯🇵 · Rimantas Lazauskas🇫🇷 · Jaume Carbonell🇫🇷
We have investigated the possible existence of a $^{7}$ H resonant state, considered as a five-body system consisting of a $^{3}$ H core with four valence neutrons. To this aim, an effective n- $^{3}$ H potential is constructed in order to reproduce the low energy elastic neutron scattering on $^{3}$ H phase shifts and the $^{5}$ H resonant ground state in terms of $^{3}$ H-n-n system. The variational Gaussian Expansion Method is used to solve the 5-body Schrödinger equation, while the resonant state parameters were estimated by means of the stabilization method. We have not found any sign of a narrow low energy resonance in the vicinity of $^{3}$ H+4n threshold. However, we have identified a very broad structure at $E_{R} \approx 9$ MeV above this threshold, which corresponds to the $^{7}$ H J $^{π}$ =1/2 $^{+}$ ground state. In the vicinity of this state, we have also identified a broad structure corresponding to the ground state of $^{6}$ H isotope with quantum numbers $J^{π} = 2^{-}$ .
nucl-thhep-phnucl-exPLB(2022)·7 citations
05
Nuclear fission and fusion in a random-walk model
M. Albertsson🇸🇪
This dissertation deals with theoretical descriptions of nuclear fission and synthesis of superheavy elements via fusion. The associated shape evolutions are treated using a random-walk approach where both the potential energy and the nuclear level density influence the dynamics. The work in this thesis extends the random-walk model by, in addition to the previous description of fragment mass yields, also simulating how much kinetic energy the fission-fragments obtain and the number of neutrons they emit, as well as how these two quantities are correlated. The thesis also presents studies of how different ways of fissioning, called fission modes, are present in different nuclei and how the presence of these modes depends on the energy of the system. The model is furthermore applied to the description of the shape evolution in fusion for production of superheavy elements.
nucl-th1 citation
06
Splitting of proton-antiproton directed flow in relativistic heavy-ion collisions
Piotr Bozek🇵🇱
The rapidity dependent directed flow of particles produced in a relativistic heavy ion collision can be generated in the hydrodynamic expansion of a tilted source. The asymmetry of the pressure leads to a build up of a directed flow of matter with respect to the collision axis. The experimentally observed ordering of the directed flow of baryons, pions and antibaryons can be described as resulting from the expansion of a baryon inhomogeneous fireball. An uneven distribution of baryons in the transverse plane leads to an asymmetry in the collective push for protons and antiprotons. Precise measurements of the collective flow as a function of rapidity could serve as a strong constraint on mechanism of baryon stopping in the early phase of the collision.
nucl-thhep-phnucl-exPRC(2022)·31 citations
07
The origin of elements: the need for UV spectra
Chiaki Kobayashi
Thanks to the long-term collaborations between nuclear and astrophysics, we have good understanding on stellar nucleosynthesis, except for the elements around Ti and some neutron-capture elements. From the comparison between observations and Galactic chemical evolution models, it is necessary to have the rapid neutron-capture process associated with core-collapse supernovae, although the explosion mechanism is unknown. The impact of rotating massive stars is also shown in this paper. Many of the key elements can be exclusively obtained in the UV, and therefore without UV spectra it would not be possible to fully understand the origin of elements in the universe.
↳ astro-ph.SRastro-ph.GAastro-ph.IMnucl-thExper.Astron.(2023)·1 citation
08
Pion scalar, vector and tensor form factors from a contact interaction
Xiaobin Wang🇨🇳 · Zanbin Xing🇨🇳 · Jiayin Kang🇨🇳 · Khépani Raya🇪🇸 · Lei Chang🇨🇳
The pion scalar, vector and tensor form factors are calculated within a symmetry-preserving contact interaction model (CI) of quantum chromodynamics (QCD), encompassed within a Dyson-Schwinger and Bethe-Salpeter equations approach. In addition to the traditional rainbow-ladder truncation, a modified interaction kernel for the Bethe-Salpeter equation is adopted. The implemented kernel preserves the vector and axial-vector Ward-Takahashi identities, while also providing additional freedom. Consequently, new tensor structures are generated in the corresponding interaction vertices, shifting the location of the mass poles appearing in the quark-photon and quark tensor vertex and yielding a notorious improvement in the final results. Despite the simplicity of the CI, the computed form factors and radii are compatible with recent lattice QCD simulations.
↳ hep-phhep-latnucl-thPRD(2022)·20 citations
09
A general, scale-independent description of the sound speed in neutron stars
Christian Ecker · Luciano Rezzolla
Using more than a million randomly generated equations of state that satisfy theoretical and observational constraints we construct a novel, scale-independent description of the sound speed in neutron stars where the latter is expressed in a unit-cube spanning the normalised radius, $r / R$ , and the mass normalized to the maximum one, $M / M_{TOV}$ . From this generic representation, a number of interesting and surprising results can be deduced. In particular, we find that light (heavy) stars have stiff (soft) cores and soft (stiff) outer layers, respectively, or that the maximum of the sound speed is located at the center of light stars but moves to the outer layers for stars with $M / M_{TOV} ≳ 0.7$ , reaching a constant value of $c_{s}^{2} = 1/2$ as $M \to M_{TOV}$ . We also show that the sound speed decreases below the conformal limit $c_{s}^{2} = 1/3$ at the center of stars with $M = M_{TOV}$ . Finally, we construct an analytic expression that accurately describes the radial dependence of the sound speed as a function of the neutron-star mass, thus providing an estimate of the maximum sound speed expected in a neutron star.
↳ gr-qcastro-ph.HEnucl-thApJL(2022)·84 citations
10
Hydrodynamic manifestations of gravitational chiral anomaly
G. Yu. Prokhorov🇷🇺 · O. V. Teryaev🇷🇺 · V. I. Zakharov🇷🇺
The conservation of an axial current modified by the gravitational chiral anomaly implies the universal transport phenomenon (Kinematical Vortical Effect) dependent solely on medium vorticity and acceleration but not dependent explicitly on its temperature and density. This general analysis is verified for the case of massless fermions with spin 1/2.
↳ hep-thgr-qcnucl-thPRL(2022)·20 citations
11
Bound State Formation in Time Dependent Potentials
Jan Rais🇩🇪 · Hendrik van Hees🇩🇪 · Carsten Greiner🇩🇪
We study the temporal formation of quantum mechanical bound states within a one-dimensional attractive square-well potential, by first solving the time-independent Schroedinger equation and then study a time dependent system with an external time-dependent potential. For this we introduce Gaussian potentials with different spatial and temporal extensions, and generalize this description also for subsequent pulses and for random, noisy potentials. Our main goal is to study the time scales, in which the bound state is populated and depopulated. Particularly we clarify a likely connection between the uncertainty relation for energy and time and the transition time between different energy eigenstates. We demonstrate, that the formation of states is not delayed due to the uncertainty relation but follows the pulse shape of the perturbation. In addition we investigate the (non-)applicability of first-order perturbation theory on the considered quantum system.
↳ quant-phhep-thnucl-thPRC(2022)·10 citations
12
Rebuttal to: "Comment on Scaling properties of background- and chiral-magnetically-driven charge separation in heavy ion collisions at $s_{NN} = 200$ GeV"
Roy A. Lacey🇺🇸 · Niseem Magdy (Depts. of Chemistry and Physics, Stony Brook University, Stony Brook, New York, USA)🇺🇸
Recently, F. Wang commented on our work "Scaling properties of background- and chiral-magnetically-driven charge separation in heavy ion collisions at $s_{NN} = 200$ GeV" and made several claims to support his conclusion that our results are fallacious. His conclusion and claims are not only incorrect; they show a fundamental disconnect with the rudiments of the $R_{Ψ_{2}} (Δ S)$ correlator. This rebuttal addresses the root misconception responsible for Wang's false claims.
↳ nucl-exhep-exhep-phnucl-th0 citations
13
Emergence of mass in the gauge sector of QCD
J. Papavassiliou🇪🇸
It is widely accepted nowadays that gluons, while massless at the level of the fundamental QCD Lagrangian,acquire an effective mass through the non-Abelian implementation of the classic Schwinger mechanism. The key dynamical ingredient that triggers the onset of this mechanism is the formation of composite massless poles inside the fundamental vertices of the theory. These poles enter in the evolution equation of the gluon propagator, and affect nontrivially the way the Slavnov-Taylor identities of the vertices are resolved,inducing a smoking-gun displacement in the corresponding Ward identities. In this article we present a comprehensive review of the pivotal concepts associated with this dynamical scenario, emphasizing the synergy between functional methods and lattice simulations, and highlighting recent advances that corroborate the action of the Schwinger mechanism in QCD.
↳ hep-phhep-lathep-thnucl-thCPC(2022)·52 citations

Affiliations

first authorsco-authorsvia INSPIRE