Nuclear Theory·nucl-th

Thursday·May 24, 2018

9 papers—3 primary·6 cross-listed

01
Unitary evolution with fluctuations and dissipation
Aurel Bulgac · Shi Jin · Ionel Stetcu
We outline an extension of the classical Langevin equation to a quantum formulation of the treatment of dissipation and fluctuations of all collective degrees of freedom with unitary evolution of a many-fermion system within an extension of the time-dependent density functional theory. We illustrate the method by computing the distribution of fission fragment yields for $^{258}$ Fm in a quantum hydrodynamic approach and a typical trajectory with full unrestricted density functional theory augmented with dissipation and fluctuations.
nucl-thPRC(2019)·40 citations
02
Dynamically integrated transport approach for heavy-ion collisions at high baryon density
Yukinao Akamatsu🇯🇵 · Masayuki Asakawa🇯🇵 · Tetsufumi Hirano🇯🇵 · Masakiyo Kitazawa🇯🇵 · Kenji Morita🇵🇱 · Koichi Murase🇯🇵 · Yasushi Nara🇯🇵 · Chiho Nonaka🇯🇵 · Akira Ohnishi🇯🇵
We develop a new dynamical model for high energy heavy-ion collisions in the beam energy region of the highest net-baryon densities on the basis of non-equilibrium microscopic transport model JAM and macroscopic 3+1D hydrodynamics by utilizing a dynamical initialization method. In this model,dynamical fluidization of a system is controlled by the source terms of the hydrodynamic fields. In addition, time dependent core-corona separation of hot regions is implemented. We show that our new model describes multiplicities and mean transverse mass in heavy-ion collisions within a beam energy region of $3 < s_{N N} < 30$ GeV. Good agreement of the beam energy dependence of the $K^{+} / π^{+}$ ratio is obtained, which is explained by the fact that a part of the system is not thermalized in our core-corona approach.
nucl-thhep-phnucl-exPRC(2018)·87 citations
03
Nuclear Structure from the In-Medium Similarity Renormalization Group
Heiko Hergert🇺🇸 · Jiangming Yao🇺🇸 · Titus D. Morris🇺🇸 · Nathan M. Parzuchowski🇺🇸 · Scott K. Bogner🇺🇸 · Jonathan Engel🇺🇸
Efforts to describe nuclear structure and dynamics from first principles have advanced significantly in recent years. Exact methods for light nuclei are now able to include continuum degrees of freedom and treat structure and reactions on the same footing, and multiple approximate, computationally efficient many-body methods have been developed that can be routinely applied for medium-mass nuclei. This has made it possible to confront modern nuclear interactions from Chiral Effective Field Theory, that are rooted in Quantum Chromodynamics with a wealth of experimental data. Here, we discuss one of these efficient new many-body methods, the In-Medium Similarity Renormalization Group (IMSRG), and its applications in modern nuclear structure theory. The IMSRG evolves the nuclear many-body Hamiltonian in second-quantized form through continuous unitary transformations that can be implemented with polynomial computational effort. Through suitably chosen generators, we drive the matrix representation of the Hamiltonian in configuration space to specific shapes, e.g., to implement a decoupling of low- and high-energy scales, or to extract energy eigenvalues for a given nucleus. We present selected results from Multireference IMSRG (MR-IMSRG) calculations of open-shell nuclei, as well as proof-of-principle applications for intrinsically deformed medium-mass nuclei. We discuss the successes and prospects of merging the (MR-)IMSRG with many-body methods ranging from Configuration Interaction to the Density Matrix Renormalization Group, with the goal of achieving an efficient simultaneous description of dynamic and static correlations in atomic nuclei.
nucl-thJ.Phys.Conf.Ser.(2018)·18 citations
04
Thermal corrections to the gluon magnetic Debye mass
Alejandro Ayala🇲🇽 · Jorge David Castaño-Yepes🇲🇽 · C. A. Dominguez🇿🇦 · S. Hernandez-Ortiz🇲🇽 · L. A. Hernandez🇿🇦 · M. Loewe🇲🇽 · D. Manreza Paret🇲🇽 · R. Zamora🇨🇱
We compute the gluon polarization tensor in a thermo-magnetic environment in the strong magnetic field limit at zero and high temperature. The magnetic field effects are introduced using Schwinger's proper time method. Thermal effects are computed in the HTL approximation. At zero temperature, we reproduce the well-known result whereby for a non-vanishing quark mass, the polarization tensor reduces to the parallel structure and its coefficient develops an imaginary part corresponding to the threshold for quark-antiquark pair production. This coefficient is infrared finite and simplifies considerably when the quark mass vanishes. Keeping always the field strength as the largest energy scale, in the high temperature regime we analyze two complementary hierarchies of scales: $q^{2} ≪ m_{f}^{2} ≪ T^{2}$ and $m_{f}^{2} ≪ q^{2} ≪ T^{2}$ . In the latter, we show that the polarization tensor is infrared finite as $m_{f}$ goes to zero. In the former, we discuss the thermal corrections to the magnetic Debye mass.
↳ hep-phhep-thnucl-thRev.Mex.Fis.(2020)·26 citations
05
Thermo-magnetic evolution of the QCD strong coupling
Alejandro Ayala🇲🇽 · C. A. Dominguez🇿🇦 · Saul Hernandez-Ortiz🇲🇽 · L. A. Hernandez🇿🇦 · M. Loewe🇲🇽 · D. Manreza Paret🇲🇽 · R. Zamora🇨🇱
We study the one-loop gluon polarization tensor at zero and finite temperature in the presence of a magnetic field, to extract the thermo-magnetic evolution of the strong coupling $α_{s}$ . We analyze four distinct regimes, to wit, the small and large field cases, both at zero and at high temperature. From a renormalization group analysis we show that at zero temperature, either for small or large magnetic fields, and for a fixed transferred momentum $Q^{2}$ , $α_{s}$ grows with the field strength with respect to its vacuum value. However, at high temperature and also for a fixed value of $Q^{2}$ we find two different cases: When the magnetic field is even larger than the squared temperature, $α_{s}$ also grows with the field strength. On the contrary, when the squared temperature is larger than the magnetic field, a turnover behavior occurs and $α_{s}$ decreases with the field strength. This thermo-magnetic behavior of $α_{s}$ can help explain the inverse magnetic catalysis phenomenon found by lattice QCD calculations.
↳ hep-phhep-thnucl-thPRD(2018)·87 citations
06
Chiral Vortical Effect For An Arbitrary Spin
Xu-Guang Huang🇨🇳 · Andrey V. Sadofyev🇺🇸
The spin Hall effect of light attracted enormous attention in the literature due to the ongoing progress in developing of new optically active materials and metamaterials with non-trivial spin-orbit interaction. Recently, it was shown that rotating fermionic systems with relativistic massless spectrum may exhibit a 3d analogue of the spin Hall current -- the chiral vortical effect (CVE). Here we show that CVE is a general feature of massless particles with an arbitrary spin. We derive the semi-classical equations of motion in rotating frame from the first principles and show how by coordinate transformation in the phase space it can be brought to the intuitive form proposed in [1]. Our finding clarifies the superficial discrepancies in different formulations of the chiral kinetic theory for rotating systems. We then generalize the chiral kinetic theory, originally introduced for fermions, to an arbitrary spin and study chirality current in a general rotating chiral medium. We stress that the higher-spin realizations of CVE can be in principle observed in various setups including table-top experiments on quantum optics.
↳ hep-thcond-mat.othernucl-thphysics.opticsJHEP(2019)·47 citations
07
A Cautionary Tale: The Coulomb Modified ANC for the $1/ 2_{2}^{+}$ State in $^{17}$ O
N. Keeley · K.W. Kemper · K. Rusek
We discuss the impact of the uncertainty ( $\pm 8$ keV) in the excitation energy of the astrophysically important 6.356 MeV $1/ 2_{2}^{+}$ state of $^{17}$ O on the precision with which the Coulomb reduced ANC ( $C$ ) for the $⟨^{17} O (1/ 2_{2}^{+}) ∣ \protect^{13} C + α ⟩$ overlap can be extracted from direct reaction data. We find a linear dependence of $C^{2}$ on the binding energy, the value extracted varying by a factor of 4 over the range $E_{ex} = 6.356$ -- $6.348$ MeV. This represents an intrinsic limit on the precision with which $C^{2}$ can be determined which cannot be improved unless or until the uncertainty in $E_{ex}$ is reduced.
↳ nucl-exnucl-thEPJA(2018)·5 citations
08
Bose enhancement, the Liouville effective action and the high multiplicity tail in p-A collisions
Alex Kovner🇺🇸 · Vladimir V. Skokov🇺🇸
In the framework of dense-dilute CGC approach we study fluctuations in the multiplicity of produced particles in p-A collisions. We show that the leading effect that drives the fluctuations is the Bose enhancement of gluons in the proton wave function. We explicitly calculate the moment generating function that resums the effects of Bose enhancement. We show that it can be understood in terms of the Liouville effective action for the composite field which is identified with the fluctuating density, or saturation momentum of the proton. The resulting probability distribution turns out to be very close to the gamma-distribution. We also calculate the first correction to this distribution which is due to pairwise Hanbury Brown-Twiss correlations of produced gluons.
↳ hep-phnucl-thPRD(2018)·18 citations
09
Does shape matter? v_2 vs eccentricity in small x gluon production
Alex Kovner🇺🇸 · Vladimir V. Skokov🇺🇸
We study analytically and numerically effects of spatial eccentricity of the projectile shape on the second flow harmonic in inclusive gluon production in p-A collisions in the CGC framework. Keeping the collision area fixed, we find that the two quantities are anti-correlated.
↳ hep-phnucl-thPLB(2018)·25 citations

Affiliations

first authorsco-authorsvia INSPIRE