Nuclear Theory·nucl-th

Monday·December 24, 2018

12 papers—5 primary·7 cross-listed

06
[Submitted on 19 Dec 2018] (cross-list from hep-lat)
Chiral crossover in QCD at zero and non-zero chemical potentials
A. Bazavov🇺🇸 · H.-T. Ding🇨🇳 · P. Hegde🇮🇳 · O. Kaczmarek🇨🇳 · F. Karsch🇩🇪 · N. Karthik🇺🇸 · E. Laermann🇩🇪 · Anirban Lahiri🇩🇪 · R. Larsen🇺🇸 · S.-T. Li🇨🇳 · Swagato Mukherjee🇺🇸 · H. Ohno🇯🇵 and 5 other authors
We present results for pseudo-critical temperatures of QCD chiral crossovers at zero and non-zero values of baryon ( $B$ ), strangeness ( $S$ ), electric charge ( $Q$ ), and isospin ( $I$ ) chemical potentials $μ_{X = B, Q, S, I}$ . The results were obtained using lattice QCD calculations carried out with two degenerate up and down dynamical quarks and a dynamical strange quark, with quark masses corresponding to physical values of pion and kaon masses in the continuum limit. By parameterizing pseudo-critical temperatures as $T_{c} (μ_{X}) = T_{c} (0) [1 - κ_{2}^{X} (μ_{X} / T_{c} (0))^{2} - κ_{4}^{X} (μ_{X} / T_{c} (0))^{4}]$ , we determined $κ_{2}^{X}$ and $κ_{4}^{X}$ from Taylor expansions of chiral observables in $μ_{X}$ . We obtained a precise result for $T_{c} (0) = (156.5 \pm 1.5) MeV$ . For analogous thermal conditions at the chemical freeze-out of relativistic heavy-ion collisions, i.e., $μ_{S} (T, μ_{B})$ and $μ_{Q} (T, μ_{B})$ fixed from strangeness-neutrality and isospin-imbalance, we found $κ_{2}^{B} = 0.012 (4)$ and $κ_{4}^{B} = 0.000 (4)$ . For $μ_{B} ≲ 300 MeV$ , the chemical freeze-out takes place in the vicinity of the QCD phase boundary, which coincides with the lines of constant energy density of $0.42 (6) GeV/fm^{3}$ and constant entropy density of $3.7 (5) fm^{- 3}$ .
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1812.08235 [pdf]
PLB(2019)·878 citations
07
[Submitted on 20 Dec 2018] (cross-list from nucl-ex)
First observation of unbound $^{11}$ O, the mirror of the halo nucleus $^{11}$ Li
T.B. Webb · S.M. Wang · K.W. Brown · R.J. Charity · J.M. Elson · J. Barney · G. Cerizza · Z. Chajecki · J. Estee · D.E.M. Hoff · S.A. Kuvin · W.G. Lynch and 14 other authors
The structure of the extremely proton-rich nucleus $_{8}^{11}$ O $_{3}$ , the mirror of the two-neutron halo nucleus $_{3}^{11}$ Li $_{8}$ , has been studied experimentally for the first time. Following two-neutron knockout reactions with a $^{13}$ O beam, the $^{11}$ O decay products were detected after two-proton emission and used to construct an invariant-mass spectrum. A broad peak of width $\sim$ 3\,MeV was observed. Within the Gamow coupled-channel approach, it was concluded that this peak is a multiplet with contributions from the four-lowest $^{11}$ O resonant states: $J^{π}$ =3/2 $_{1}^{-}$ , 3/2 $_{2}^{-}$ , 5/2 $_{1}^{+}$ , and 5/2 $_{2}^{+}$ . The widths and configurations of these states show strong, non-monotonic dependencies on the depth of the $p$ - $^{9}$ C potential. This unusual behavior is due to the presence of a broad threshold resonant state in $^{10}$ N, which is an analog of the virtual state in $^{10}$ Li in the presence of the Coulomb potential. After optimizing the model to the data, only a moderate isospin asymmetry between ground states of $^{11}$ O and $^{11}$ Li was found.
Comments:
6 pages, three figures
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1812.08880 [pdf]
PRL(2019)·45 citations
08
[Submitted on 21 Dec 2018] (cross-list from nucl-ex)
Fine structure of giant resonances: What can be learned
Peter von Neumann-Cosel🇩🇪
Fine structure of giant resonances (GR) has been established in recent years as a global phenomenon across the nuclear chart and for different types of resonances. A quantitative description of the fine structure in terms of characteristic scales derived by wavelet techniques is discussed. By comparison with microscpic calculations of GR strength distributions one can extract information on the role of different decay mechanisms contributing to the width of GRs. The observed cross-section fluctuations contain information on the level density (LD) of states with a given spin and parity defined by the multipolarity of the GR.
Comments:
11 pages, 6 figures, Invited Lecture presented at the Zakopane Conference on Nuclear Physics "Extremes of the Nuclear Landscape", Zakopane, Poland, August 26 - September 2, 2018
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1812.09070 [pdf]
Acta Phys.Polon.B(2019)·1 citation
09
[Submitted on 21 Dec 2018] (cross-list from nucl-ex)
Gamma strength functions and the Brink-Axel hypothesis
Peter von Neumann-Cosel
Experimental tests of the Brink-Axel hypothesis relating gamma strength functions (GSF) deduced from absorption and emission experiments are discussed. High-resolution inelastic proton scattering at energies of a few hundred MeV and at very forwrd angles including $0^{\circ}$ presents a new approach to test the validity of the BA hypothesis in the energy region of the pygmy dipole resonance. Such data not only provide the GSF but also the level density and thus permit an independent test of their model-dependent decomposition in the Oslo method.
Comments:
9 pages, 6 figures, Invited talk presented at the 6th International Workshop on Compound-Nuclear Reactions and Related Topics, Berkeley, USA, September 24-28, 2018
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1812.09072 [pdf]
Springer Proc.Phys.(2020)·0 citations
10
[Submitted on 21 Dec 2018] (cross-list from physics.chem-ph)
Improvement of functionals in density functional theory by the inverse Kohn--Sham method and density functional perturbation theory
Tomoya Naito · Daisuke Ohashi · Haozhao Liang
We propose a way to improve energy density functionals (EDFs) in the density functional theory based on the combination of the inverse Kohn--Sham method and the density functional perturbation theory. Difference between the known EDF and the exact one is treated as the first-order perturbation. As benchmark calculations, we reproduce the theoretical exchange and correlation functionals in the local density approximation. Systems of noble-gas atoms are used for benchmark calculations, and the ground-state energies and densities, as well as the functionals, are reproduced with good accuracies.
Comments:
17 pages, 5 figures, 5 tables
Subjects:
physics.chem-ph (physics.chem-ph); Strongly Correlated Electrons (cond-mat.str-el); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph); Computational Physics (physics.comp-ph)
arXiv:
1812.09285 [pdf]
J.Phys.B(2019)·7 citations
11
[Submitted on 21 Dec 2018] (cross-list from hep-th)
Adding new branches to the "Christmas tree" of the quasinormal spectrum of black branes
Sašo Grozdanov🇺🇸 · Andrei O. Starinets🇬🇧
In holography, quasinormal spectra of black branes coincide with the poles of retarded finite-temperature correlation functions of a dual quantum field theory in the limit of infinite number of relevant degrees of freedom such as colours. For asymptotically anti-de Sitter backgrounds, the spectra form a characteristic pattern in the complex frequency plane, colloquially known as the "Christmas tree". At infinite coupling, the tree has only one pair of branches. At large but finite coupling, the branches become more dense and lift up towards the real axis, consistent with the expectation of forming a branch cut in the limit of zero coupling. However, it is known that at zero coupling, the corresponding correlators generically have not one but multiple branch cuts separated by intervals proportional to the Matsubara frequency. This suggests the existence of multiple branches of the "Christmas tree" spectrum in dual gravity. In this note, we show numerically how these additional branches of the spectrum can emerge from the dual gravitational action with higher-derivative terms. This phenomenon appears to be robust, yet, reproducing the expected weak coupling behaviour of the correlators quantitatively implies the existence of certain constraints on the coefficients of the higher-derivative terms of the dual gravity theory.
Comments:
V2: 13 pages, 8 figures. Version to appear in JHEP
Subjects:
High Energy Physics — Theory (hep-th); Strongly Correlated Electrons (cond-mat.str-el); Nuclear Theory (nucl-th)
arXiv:
1812.09288 [pdf]
JHEP(2019)·28 citations
12
[Submitted on 21 Dec 2018] (cross-list from hep-ph)
Probing Generalized Parton Distributions through the photoproduction of a $γ π$ pair
G. Duplančić🇭🇷 · K. Passek-Kumerički🇭🇷 · B. Pire🇫🇷 · L. Szymanowski🇵🇱 · S. Wallon🇫🇷
We study in the framework of collinear QCD factorization the photoproduction of a $γ π$ pair with a large invariant mass and a small transverse momentum, as a new way to access generalized parton distributions. In the kinematics of JLab 12-GeV, we demonstrate the feasibility of this measurement and show the extreme sensitivity of the unpolarized cross section to the axial quark GPDs.
Comments:
7 pages, 4 figures, to appear in the proceedings of Diffraction and Low-x 2018, 26 August - 1 September 2018, Reggio Calabria, Italy
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1812.09307 [pdf]
Acta Phys.Polon.Supp.(2019)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Chiral crossover in QCD at zero and non-zero chemical potentials

First observation of unbound 11O, the mirror of the halo nucleus 11Li

Fine structure of giant resonances: What can be learned

Gamma strength functions and the Brink-Axel hypothesis

Improvement of functionals in density functional theory by the inverse Kohn--Sham method and density functional perturbation theory

Adding new branches to the "Christmas tree" of the quasinormal spectrum of black branes

Probing Generalized Parton Distributions through the photoproduction of a γπ pair

Affiliations

First observation of unbound $^{11}$ O, the mirror of the halo nucleus $^{11}$ Li

Probing Generalized Parton Distributions through the photoproduction of a $γ π$ pair