Nuclear Theory·nucl-th

Tuesday·April 21, 2020

15 papers—9 primary·6 cross-listed

01
[Submitted on 17 Apr 2020]
Quantifying uncertainties in neutron-alpha scattering with chiral nucleon-nucleon and three-nucleon forces
Konstantinos Kravvaris · Kevin R. Quinlan · Sofia Quaglioni · Kyle A. Wendt · Petr Navratil
Background: Modern ab initio theory combined with high-quality nucleon-nucleon (NN) and three-nucleon (3N) interactions from chiral effective field theory (EFT) can provide a predictive description of low-energy light-nuclei reactions relevant for astrophysics and fusion-energy applications. However, the high cost of computations has so far impeded a complete analysis of the uncertainty budget of such calculations. Purpose: Starting from NN potentials up to fifth order (N4LO) combined with leading-order 3N forces, we study how the order-by-order convergence of the chiral expansion and confidence intervals for the 3N contact and contact-plus-one-pion-exchange low-energy constants (cE and cD) contribute to the overall uncertainty budget of many-body calculations of neutron-He elastic scattering. Methods: We compute structure and reaction observables for three-, four- and five-nucleon systems within the ab initio frameworks of the no-core shell model an no-core shell model with continuum. Using a small set of design runs, we construct a Gaussian process model (GPM) that acts as a statistical emulator for the theory. With this, we gain insight into how uncertainties in the 3N low-energy constants propagate throughout the calculation and determine the Bayesian posterior distribution of these parameters with Markov-Chain Monte-Carlo.
Comments:
12 pages, 11 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2004.08474 [pdf]
PRC(2020)·44 citations
02
[Submitted on 18 Apr 2020]
Locating the freeze-out curve in heavy-ion collisions
Marcus Bluhm (SUBATECH, Nantes and Darmstadt, EMMI)🇫🇷 · Marlene Nahrgang (SUBATECH, Nantes and Darmstadt, EMMI)🇫🇷 · Jan M. Pawlowski (Heidelberg U. and Darmstadt, EMMI)🇩🇪
Based on transport equations we argue that the chiral dynamics in heavy-ion collisions at high collision energies effectively decouples from the thermal physics of the fireball. With full decoupling at LHC energies the chiral condensate relaxes to its vacuum expectation value on a much shorter time scale than the typical evolution time of the fluid dynamical fields and their fluctuations. In particular, the net-baryon density remains coupled to the bulk evolution at all collision energies. As the mass scales of the hadrons are controlled by the chiral condensate, it is reasonable to employ vacuum masses in the statistical description of the hadron production at the chemical freeze-out for high collision energies. We predict that at lower collision energies the coupling of the chiral condensate to the thermal medium gradually increases with consequences for the related hadronic masses. A new estimate for the location of the freeze-out curve takes these effects into account.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2004.08608 [pdf]
8 citations
03
[Submitted on 18 Apr 2020]
Induced surface and curvature tensions equation of state of hard spheres and its virial coefficients
Nazar S. Yakovenko🇺🇦 · Kyrill A. Bugaev🇺🇦 · Larissa V. Bravina🇳🇴 · Evgeny E. Zabrodin🇳🇴
Here we present new results obtained for the equation of state with induced surface and curvature tensions. The explicit formulas for the first five virial coefficients of system pressure and for the induced surface and curvature tension coefficients are derived and their possible applications are briefly discussed.
Comments:
Talk at the ICNFP2019
Subjects:
Nuclear Theory (nucl-th); Statistical Mechanics (cond-mat.stat-mech)
arXiv:
2004.08693 [pdf]
IJMPE(2020)·0 citations
04
[Submitted on 19 Apr 2020]
Anomalous Lorentz transformation and side jump of a massive fermion
Feng Li🇨🇳 · Shuai Y.F. Liu🇨🇳
The side jump in the anomalous Lorentz transformation, arising from the spin-orbit interactions, plays important roles in various intriguing physics, such as chiral vortical effects and spin polarization. In this work, the side jump of the spin-half massive particles, which has rarely been discussed, is visualized and evaluated for the first time. A compact analytical expression describing such side jumps is derived, and found approaching the one describing the chiral fermions in the massless limit. It is further demonstrated that the covariance of the total angular momentum, which would be broken by a normal Lorentz transformation, is restored after the obtained side jumps are taken into account.
Comments:
5 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th)
arXiv:
2004.08910 [pdf]
7 citations
05
[Submitted on 20 Apr 2020]
Fractionalized Quasiparticles in Dense Baryonic Matter
Mannque Rho🇫🇷
I discuss a novel scenario on how baryonic matter could turn into a Fermi liquid of fractionalized baryons driven by high density inside compact stars. It involves the "hidden" local vector bosons $ρ$ and $ω$ together with the "hidden" scale symmetry dilaton $χ$ , both taken to be "dual" to the quarks and gluons of QCD in the sense of quark $\leftrightarrow$ hadron duality and offers a possibility, exploiting the "Cheshire Cat Principle", to unify the "dichotomy" of baryons described in terms of skyrmions and fractional quantum Hall (FQH) droplets {\it and} to explore how the baryonic matter could behave as density goes way beyond the normal nuclear matter density to the density regime where "deconfined" quarks are presumed to figure. The question is raised as to whether the fractionalized characteristics of the "stuff" -- whatever they are -- can be "probed" in the dense star core of compact stars.
Comments:
16 pages, no figures; rewritten with current developments added
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2004.09082 [pdf]
12 citations
06
[Submitted on 20 Apr 2020]
Supersymmetric quantum mechanics to study the 16.8 MeV resonance state of $^{9}$ B
S. K. Dutta · D. Gupta · Swapan K. Saha
The study of a high-lying resonant state of $^{9}$ B is carried out using supersymmetric quantum mechanics (SQM). The resulting isospectral potentials are very deep and narrow and the generated wave functions identify the resonance at 16.84 MeV with a width of 69 keV. The present work shows that SQM can be successfully applied for detection of high-lying resonances in unstable nuclei.
Comments:
3 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2004.09105 [pdf]
0 citations
07
[Submitted on 20 Apr 2020]
Effects of anomalous magnetic moment of quarks on the dilepton production from hot and dense magnetized quark matter using the NJL model
Snigdha Ghosh🇮🇳 · Nilanjan Chaudhuri🇮🇳 · Sourav Sarkar🇮🇳 · Pradip Roy🇮🇳
Dilepton production rate (DPR) from hot and dense quark matter is studied in the presence of an arbitrary external magnetic field using the 2-flavour Nambu--Jona-Lasinio (NJL) model. The anomalous magnetic moment (AMM) of the quarks is taken into consideration while calculating the constituent quark mass as well as the DPR from the thermo-magnetic medium. An infinite number of quark Landau levels is incorporated so that no approximations are made on the strength of the background magnetic field. The analytic structure of the two point vector current correlation function in the complex energy plane reveals that, in addition to the usual Unitary cut, a non-trival Landau cut appears in the physical kinematic domains solely due to the external magnetic field. Moreover, these kinematic domains of the Unitary and Landau cuts are found to be significantly modified due to the AMM of the quarks. With finite AMM of the quarks, for certain values of the external magnetic field, the kinematically forbidden gap between the Unitary and Landau cuts are shown to vanish leading to the generation of a continuous spectrum of dilepton emission over the whole invariant mass region not observed earlier.
Comments:
Version published in Physical Review D
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2004.09203 [pdf]
PRD(2020)·39 citations
08
[Submitted on 20 Apr 2020]
Heavy $Ω_{c}$ and $Ω_{b}$ baryons in the quark model
E. Ortiz-Pacheco🇲🇽 · R. Bijker🇲🇽 · A. Giachino🇮🇹 · E. Santopinto🇮🇹
In this contribution, we present a study of ground- and excited-state $Ω_{c}$ and $Ω_{b}$ baryons consisting of two strange quarks and a heavy charm or bottom quark. An analysis in the quark model shows that the recently observed excited $Ω_{c}$ and $Ω_{b}$ states can be interpreted in terms of $λ$ -mode excitations.
Comments:
6 pages, 3 figures, 3 tables, invited talk, XLII Symposium on Nuclear Physics, Cocoyoc, Mexico, January 6-9, 2020, to be published in J. Phys. Conf. Ser
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2004.09409 [pdf]
J.Phys.Conf.Ser.(2020)·16 citations
09
[Submitted on 20 Apr 2020]
Analysis of the data on spin density matrix elements for $γ p \to K^{*+} Λ$
Neng-Chang Wei🇨🇳 · Ai-Chao Wang🇨🇳 · Fei Huang🇨🇳 · De-Min Li🇨🇳
In our previous work [Phys. Rev. C {\bf 96}, 035206 (2017)], the high-precision differential cross-section data for $γ p \to K^{*+} Λ$ reported by the CLAS Collaboration has been analyzed within an effective Lagrangian approach. It was found that apart from the $t$ -channel $K$ , $K^{*}$ , and $κ$ exchanges, the $u$ -channel $Λ$ , $Σ$ , and $Σ^{*}$ exchanges, the $s$ -channel $N$ exchange, and the interaction current, one needs to introduce at least two nucleon resonances in the $s$ channel in constructing the reaction amplitudes to describe the cross-section data. One of the needed resonances is $N (2060) 5/ 2^{-}$ , and the other one could be one of the $N (2000) 5/ 2^{+}$ , $N (2040) 3/ 2^{+}$ , $N (2100) 1/ 2^{+}$ , $N (2120) 3/ 2^{-}$ , and $N (2190) 7/ 2^{-}$ resonances. In this paper, we further include in our analysis the data on spin density matrix elements for $K^{*}$ meson reported recently by the CLAS Collaboration, with the purpose being to impose further constraints on extracting the resonance contents and to gain a better understanding of the reaction mechanism. It turns out that with the new data on spin density matrix elements taken into account, only the set with the $N (2060) 5/ 2^{-}$ and $N (2000) 5/ 2^{+}$ resonances among those five possible solutions extracted from the analysis of the differential cross-section data can satisfactorily describe the data on both the differential cross sections and the spin density matrix elements. Further analysis shows that this reaction is dominated by the $t$ -channel $K$ exchange and $s$ -channel $N (2060) 5/ 2^{-}$ and $N (2000) 5/ 2^{+}$ exchanges.
Comments:
9 figures, 11 pages
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2004.09422 [pdf]
PRC(2020)·10 citations
10
[Submitted on 18 Apr 2020] (cross-list from cond-mat.quant-gas)
The fourth- and fifth-order virial coefficients from weak-coupling to unitarity
Y. Hou · J. E. Drut
In the current era of precision quantum many-body physics, one of the most scrutinized systems is the unitary limit of the nonrelativistic spin- $1/2$ Fermi gas, due to its simplicity and relevance for atomic, condensed matter, and nuclear physics. The thermodynamics of this strongly correlated system is determined by universal functions which, at high temperature, are governed by universal virial coefficients $b_{n}$ that capture the effects of the $n$ -body system on the many-body dynamics. Currently, $b_{2}$ and $b_{3}$ are well understood, but the situation is less clear for $b_{4}$ , and no predictions have been made for $b_{5}$ . To answer these open questions, we implement a nonperturbative analytic approach based on the Trotter-Suzuki factorization of the imaginary-time evolution operator, using progressively finer temporal lattice spacings. Implementing these factorizations and automated algebra codes, we obtain the interaction-induced change $Δ b_{n}$ from weak coupling to unitarity. At unitarity, we find: $Δ b_{3} = - 0.356 (4)$ , in agreement with previous results; $Δ b_{4} = 0.062 (2)$ , in agreement with all previous theoretical estimates but at odds with experimental determinations; and $Δ b_{5} = 0.078 (6)$ , which is a prediction. We show the impact of those answers on the density equation of state and Tan contact, and track their origin back to their polarized and unpolarized components.
Comments:
6 pages, 2 figures
Subjects:
Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th)
arXiv:
2004.08685 [pdf]
PRL(2020)·16 citations
11
[Submitted on 19 Apr 2020] (cross-list from hep-lat)
Magnetic susceptibility of QCD matter and its decomposition from the lattice
Gunnar S. Bali (1 and 2)🇩🇪 · Gergely Endrődi (3 and 4)🇩🇪 · Stefano Piemonte (1) ((1) Regensburg U., (2) Tata Inst., (3) Bielefeld U., (4) Frankfurt U.)🇩🇪
We determine the magnetic susceptibility of thermal QCD matter by means of first principles lattice simulations using staggered quarks with physical masses. A novel method is employed that only requires simulations at zero background field, thereby circumventing problems related to magnetic flux quantization. After a careful continuum limit extrapolation, diamagnetic behavior (negative susceptibility) is found at low temperatures and strong paramagnetism (positive susceptibility) at high temperatures. We revisit the decomposition of the magnetic susceptibility into spin- and orbital angular momentum-related contributions. The spin term -- related to the normalization of the photon lightcone distribution amplitude at zero temperature -- is calculated non-perturbatively and extrapolated to the continuum limit. Having access to both the full magnetic susceptibility and the spin term, we calculate the orbital angular momentum contribution for the first time. The results reveal the opposite of what might be expected based on a free fermion picture. We provide a simple parametrization of the temperature- and magnetic field-dependence of the QCD equation of state that can be used in phenomenological studies.
Comments:
41 pages, 12 figures, 1 ancillary python script, v2: one new figure, new reference, minor changes, v3: more figure panels, new references, volume dependence study extended, 1 formula in App C.5 corrected, minor changes
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2004.08778 [pdf]
JHEP(2020)·64 citations
12
[Submitted on 19 Apr 2020] (cross-list from hep-ph)
Magnetic field-induced anisotropic interaction in heavy quark bound states
Salman Ahamad Khan🇮🇳 · Binoy Krishna Patra🇮🇳 · Mujeeb Hasan🇮🇳
We have investigated how a strong magnetic field (B) could decipher the anisotropic interaction in heavy quark ( $Q$ ) and antiquark ( $Q ˉ$ ) bound states through the perturbative thermal QCD in real-time formalism. So we thermalize Schwinger propagator for quarks in LLL and the Feynman propagator for gluons to calculate the gluon self-energy. For the quark-loop contribution to the self-energy, the medium does not have any temperature correction and the vacuum term gives rise an anisotropic term whereas the gluon-loop yields temperature correction. This finding in quark-loop contribution corroborates the equivalence of a massless QED in (1+1)-dimension with the massless thermal QCD in strong B, which (quark sector) is reduced to (1+1)-dimension (longitudinal). Thus the permittivity of the medium behaves like as a tensor. Thus the permittivity of medium makes the $Q Q ˉ$ potential anisotropic, which resembles with a contemporary results found in lattice studies. As a result, potential for $Q Q ˉ$ -pairs aligned transverse to B is more attractive than parallel alignment. However, potential is always more attractive compared to B=0 due to softening of screening mass. However, the imaginary-part of potential becomes smaller compared to B=0. We have next investigated the effects of strong $B$ on binding energies (B.E.) and thermal widths ( $Γ$ ) of ground states of $c c ˉ$ and $b b ˉ$ in a time-independent perturbation theory, where binding energies gets increased and widths gets decreased, compared to $B = 0$ . Finally we have studied the quasi-free dissociation of bound states in a strong B. The dissociation temperatures estimated for $J / ψ$ and $Υ$ states are obtained as $1.59 T_{c}$ and $2.22 T_{c}$ , respectively, which are higher than the estimate in B=0 , thus preventing early dissolution of $Q Q ˉ$ bound states.
Comments:
26 pages with 4 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); cond-mat.soft (cond-mat.soft); Strongly Correlated Electrons (cond-mat.str-el); Nuclear Theory (nucl-th)
arXiv:
2004.08868 [pdf]
PoS(2026)·6 citations
13
[Submitted on 20 Apr 2020] (cross-list from hep-ph)
Bose-Einstein condensation phenomenology in systems with repulsive interactions
Oleh Savchuk🇺🇦 · Yehor Bondar🇺🇦 · Oleksandr Stashko🇺🇦 · Roman V. Poberezhnyuk🇺🇦 · Volodymyr Vovchenko🇺🇸 · Mark I. Gorenstein🇩🇪 · Horst Stoecker🇩🇪
The role of repulsive interactions in statistical systems of Bose particles is investigated. Three different phenomenological frameworks are considered: a mean field model, an excluded volume model, and a model with a medium dependent effective mass. All three models are tuned to yield similar equations of state, with only minor deviations from the ideal Bose gas at small chemical potentials. Our analysis indicates, however, that these models lead to qualitatively different results for the Bose-Einstein condensation phenomenon. We discuss the different aspects of this phenomenon, namely, an onset of the Bose-Einstein condensation, particle number fluctuations, and a behavior of the Bose condensate. The obtained results can be helpful for interpreting the lattice QCD data at small temperature and large isospin chemical potential and the data on multiple pion production in high energy nuclear collisions.
Comments:
10 pages, 4 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2004.09004 [pdf]
PRC(2020)·15 citations
14
[Submitted on 20 Apr 2020] (cross-list from hep-ph)
Topological susceptibility, divergent chiral density and phase diagram of chirally imbalanced QCD medium at finite temperature
Marco Ruggieri🇨🇳 · Maxim N. Chernodub🇫🇷 · Zhen-Yan Lu🇨🇳
We show that the nonlocal two-flavor Nambu--Jona-Lasinio model predicts the enhancement of both chiral and axial symmetry breaking as the chiral imbalance of hot QCD matter, regulated by a chiral chemical potential $μ_{5}$ , increases. The two crossovers are reasonably close to each other in the range of $μ_{5}$ examined here and the pseudocritical temperatures rise with $μ_{5}$ . The curvatures of the chiral and axial crossovers for the chiral quark chemical potential approximately coincide and give $κ_{5} ≃ - 0.011$ . We point out that the presence of $μ_{5}$ in thermodynamic equilibrium is inconsistent with the fact that the chiral charge is not a Noether-conserved quantity for massive fermions. The chiral chemical potential should not, therefore, be considered as a true chemical potential that sets a thermodynamically stable environment in the massive theory, but rather than as a new coupling that may require a renormalization in the ultraviolet domain. The divergence of an unrenormalized chiral density, \corr{coming from zero-point fermionic fluctuations,} is a consequence of this property. We propose a solution to this problem via a renormalization procedure.
Comments:
15 pages, 5 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2004.09393 [pdf]
PRD(2020)·24 citations
15
[Submitted on 20 Apr 2020] (cross-list from nucl-th)
Generic size dependences of pairing in ultrasmall systems: electronic nano-devices and atomic nuclei
A. Pastore🇬🇧 · P Schuck🇫🇷 · X. Viñas🇪🇸
Average, global pairing behaviours of electronic devices, like films, wires, and grains are studied with semiclassical methods, as Weyl and Thomas-Fermi approximations, in the ultrasmall, i.e., quantal regime, which exhibits strong quantum fluctuations and shell effects. This is the case also for superfluid nuclei. Results, mostly analytic, are elaborated for average size dependences, ready for easy use also in other circumstances. Comparisons with experimental results are given where possible.
Subjects:
Nuclear Theory (nucl-th); Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
arXiv:
2004.09423 [pdf]
EPJA(2023)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE