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Nuclear Theory·nucl-th

Monday·February 15, 2021

7 papers—4 primary·3 cross-listed

All7Primary4Cross-lists3
  1. 01

    User guide for the hfbcs-qrpa(v1) code

    Gianluca Colò · Xavier Roca-Maza

    We briefly explain the structure of the Hartree-Fock-Bardeen-Cooper-Schrieffer (HFBCS) and Quasi-particle Random Phase Approximation (QRPA) code hfbcs-qrpa, highlighting only the differences with the code skyrme_rpa that has been previously published [G. Colò, L. Cao, N. Van Giai, and L. Capelli, Comp. Phys. Comm. 184, 142 (2013)]. The code deals with open shell spherical systems and non-spin flip, non-charge-exchange and natural parity excitations.

    nucl-th24 citations
  2. 02

    The role of the electric Bond number in the stability of pasta phases

    Sebastian Kubis · Włodzimierz Wójcik

    The stability of pasta phases in cylindrical and spherical Wigner-Seitz (W-S) cells is examined. The electric Bond number is introduced as the ratio of electric and surface energies. In the case of a charged rod in vacuum, other kinds of instabilities appear in addition to the well known Plateau- Rayleigh mode. For the case of a rod confined in a W-S cell the variety of unstable modes is reduced. It comes from the virial theorem, which bounds the value of the Bond number from above and reduces the role played by electric forces. A similar analysis is done for the spherical W-S cell, where it appears that the inclusion of the virial theorem stabilizes all of the modes.

    nucl-thPLB(2022)·2 citations
  3. 03

    Theoretical Study of Isotope Production in The Peripheral Heavy-ion Collision 136Xe + Pb at 1 GeV/nucleon

    H. Imal🇹🇷 · R. Ogul🇹🇷

    We have studied the fragment yields emitted from the fragmentation of excited projectile nuclei in peripheral collisions of 136Xe+Pb at 1 GeV/nucleon, and measured with the high-resolution magnetic spectrometer, the Fragment Separator (FRS) of GSI. The mass, charge and isotope distributions of nuclear fragments formed in the reactions were calculated within a statistical ensemble approach and compared to the experimental data. The ensemble of excited projectilelike source nuclei were created in the framework of a previous analysis of similar reactions performed at 600 MeV/nucleon (ALADIN-experiments, GSI). In addition, the ensemble of the low-excited compound nuclei is involved in the analysis. The overall agreement between theory and experiment was very satisfactory in reproducing the experimental data of isotope yields measured in the heavy-ion collisions. It is confirmed that a broad range of elements can be reproduced within a universal statistical disintegration of the excited projectile residues.

    nucl-thnucl-exNPA(2021)·5 citations
  4. 04

    Pocket resonances in low-energy antineutrons reactions with nuclei

    Teck-Ghee Lee🇺🇸 · Orhan Bayrak🇹🇷 · Cheuk-Yin Wong🇺🇸

    Upon investigating whether the variation of the antineutron-nucleus annihilation cross-sections at very low energies satisfy Bethe-Landau's power law of behavior as a function of the antineutron momentum , we uncover unexpected regular oscillatory structures in the low antineutron energy region from 0.001 to 10 MeV, with small amplitudes and narrow periodicity in the logarithm of the antineutron energies, for large- nuclei such as Pb and Ag. Subsequent semiclassical analyses of the matrices reveal that these oscillations are pocket resonances that arise from quasi-bound states inside the pocket and the interference between the waves reflecting inside the optical potential pockets with those from beyond the potential barriers, implicit in the nuclear Ramsauer effect. They are the continuation of bound states in the continuum. Experimental observations of these pocket resonances will provide vital information on the properties of the optical model potentials and the nature of the antineutron annihilation process.

    nucl-thPLB(2021)·3 citations
  5. 05

    Chiral magnetic effect reveals the topology of gauge fields in heavy-ion collisions

    Dmitri E. Kharzeev🇺🇸 · Jinfeng Liao🇺🇸

    The topological structure of vacuum is the cornerstone of non-Abelian gauge theories describing strong and electroweak interactions within the standard model of particle physics. However, transitions between different topological sectors of the vacuum (believed to be at the origin of the baryon asymmetry of the Universe) have never been observed directly. An experimental observation of such transitions in Quantum Chromodynamics (QCD) has become possible in heavy-ion collisions, where the chiral magnetic effect converts the chiral asymmetry (generated by topological transitions in hot QCD matter) into an electric current, under the presence of the magnetic field produced by the colliding ions. The Relativistic Heavy Ion Collider program on heavy-ion collisions such as the Zr-Zr and Ru-Ru isobars, thus has the potential to uncover the topological structure of vacuum in a laboratory experiment. This discovery would have far-reaching implications for the understanding of QCD, the origin of the baryon asymmetry in the present-day Universe, and for other areas, including condensed matter physics.

    ↳ hep-phcond-mat.str-elhep-thnucl-ex+1Nature Rev.Phys.(2021)·109 citations
  6. 06

    Corrections to the hadron resonance gas from lattice QCD and their effect on fluctuation-ratios at finite density

    Rene Bellwied🇺🇸 · Szabolcs Borsanyi🇩🇪 · Zoltan Fodor🇩🇪 · Jana N. Guenther🇫🇷 · Sandor D. Katz🇭🇺 · Paolo Parotto🇩🇪 · Attila Pasztor🇭🇺 · David Pesznyak🇭🇺 · Claudia Ratti🇺🇸 · Kalman K. Szabo🇩🇪

    The hadron resonance gas (HRG) model is often believed to correctly describe the confined phase of QCD. This assumption is the basis of many phenomenological works on QCD thermodynamics and of the analysis of hadron yields in relativistic heavy ion collisions. We use first-principle lattice simulations to calculate corrections to the ideal HRG. Namely, we determine the sub-leading fugacity expansion coefficients of the grand canonical free energy, receiving contributions from processes like kaon-kaon or baryon-baryon scattering. We achieve this goal by performing a two dimensional scan on the imaginary baryon number chemical potential () - strangeness chemical potential () plane, where the fugacity expansion coefficients become Fourier coefficients. We carry out a continuum limit estimation of these coefficients by performing lattice simulations with temporal extents of using the 4stout-improved staggered action. We then use the truncated fugacity expansion to extrapolate ratios of baryon number and strangeness fluctuations and correlations to finite chemical potentials. Evaluating the fugacity expansion along the crossover line, we reproduce the trend seen in the experimental data on net-proton fluctuations by the STAR collaboration.

    ↳ hep-lathep-phnucl-thPRD(2021)·25 citations
  7. 07

    Lattice QCD equation of state at finite chemical potential from an alternative expansion scheme

    S. Borsanyi🇩🇪 · Z. Fodor🇩🇪 · J. N. Guenther🇫🇷 · R. Kara🇩🇪 · S. D. Katz🇭🇺 · P. Parotto🇩🇪 · A. Pasztor🇭🇺 · C. Ratti🇺🇸 · K. K. Szabo🇩🇪

    Taylor expansion of the equation of state of QCD suffers from shortcomings at chemical potentials . First, one faces difficulties inherent in performing such an expansion with a limited number of coefficients; second, higher order coefficients determined from lattice calculations suffer from a poor signal-to-noise ratio. In this work, we present a novel scheme for extrapolating the equation of state of QCD to finite, real chemical potential that can extend its reach further than previous methods. We present continuum extrapolated lattice results for the new expansion coefficients and show the thermodynamic observables up to .

    ↳ hep-latnucl-thPRL(2021)·201 citations

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first authorsco-authorsvia INSPIRE