Nuclear Theory·nucl-th

Monday·November 4, 2019

9 papers—4 primary·5 cross-listed

01
[Submitted on 31 Oct 2019]
Table of electronic factors for E0 electron and electron-positron pair conversion transitions
J.T.H. Dowie · T. Kibédi · T.K. Eriksen · A.E. Stuchbery
A new tabulation of electronic factors is reported for electron conversion for elements of Z from 5 to 126 and electronic factors for electron-positron pair conversion for elements of even Z from 4 to 100. The electronic factors for electron conversion, $Ω_{C E}$ (E0), were calculated using a modified version of the CATAR program developed by Pauli and Raff with a relativistic-Hartree-Fock-Slater approach (Pauli and Raff, 1975). The electronic factors for electron-positron pair conversion, $Ω_{I P F}$ (E0), were calculated using the model developed by Wilkinson (1969). The data tables presented here cover all atomic shells up to R2 and transition energies from 1 keV to 6000 keV and from 1100 keV to 8000 keV for pair conversion. A comparison with previous electronic factor tabulations is presented. Ratios of experimental {\Omega}(E0) values for 83 E0 transitions in 8 $\leq$ Z $\leq$ 98 are compared to this tabulation. Two examples of how to use the tabulation to extract E0 strengths are also included.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1911.00031 [pdf]
Atom.Data Nucl.Data Tabl.(2020)·21 citations
02
[Submitted on 1 Nov 2019]
Electric-dipole transitions in $^{6}$ Li with a fully microscopic six-body calculation
W. Horiuchi · S. Satsuka
Exploring new excitation modes and the role of the nuclear clustering has been of great interest. An interesting speculation was made in the recent photoabsorption measurement of $^{6}$ Li that implied the importance of the nuclear clustering. To understand the excitation mechanism of $^{6}$ Li, we perform a fully microscopic six-body calculation on the electric-dipole ( $E 1$ ) transitions and discuss how $^{6}$ Li is excited by the $E 1$ field as a function of the excitation energy. We show the various cluster components in the six-body wave functions and discuss the role of the nuclear clustering in the $E 1$ excitations of $^{6}$ Li.
Comments:
Submission to SciPost, Proceedings of the 24th European conference on few-body problems in physics (EFB24)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1911.00228 [pdf]
SciPost Phys.Proc.(2020)·1 citation
03
[Submitted on 31 Oct 2019]
Influence of resonances on the 11B(n,g)12B capture reaction rate. II. Capture to the first excited state of 12B
S.B. Dubovichenko · N.A. Burkova · A.V. Dzhazairov-Kakhramanov
Within the framework of the modified potential cluster model with a classification of orbital states according to Young diagrams, the possibility of prediction absentee experimental data for the total cross sections of the radiative neutron capture on 11B to the first excited state 12B at 0.95 MeV (2+) for reaction energy of 10 meV (1 meV = 10-3 eV) to 7 MeV. The reaction rate in the temperature range of 0.01 to 10.0 T9 is calculated on the basis of obtained cross sections, which take into account resonances up to 5 MeV. It is shown that low-lying resonances exercise a significant influence to the capture reaction rate. The approximation of the calculation reaction rate is carried out by the simple analytic formula.
Comments:
16p., 4 fig., 32 ref
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1911.00331 [pdf]
3 citations
04
[Submitted on 1 Nov 2019]
Charmed hadron chemistry in relativistic heavy-ion collisions
Shanshan Cao🇺🇸 · Kai-Jia Sun🇺🇸 · Shu-Qing Li🇨🇳 · Shuai Y.F. Liu🇺🇸 · Wen-Jing Xing🇨🇳 · Guang-You Qin🇨🇳 · Che-Ming Ko🇺🇸
We develop for charmed hadron production in relativistic heavy-ion collisions a comprehensive coalescence model that includes an extensive set of $s$ and $p$ -wave hadronic states as well as the strict energy-momentum conservation, which ensures the boost invariance of the coalescence probability and the thermal limit of the produced hadron spectrum. By combining our hadronization scheme with an advanced Langevin-hydrodynamics model that incorporates both elastic and inelastic energy loss of heavy quarks inside the dynamical quark-gluon plasma, we obtain a successful description of the $p_{T}$ -integrated and differential $Λ_{c} / D^{0}$ and $D_{s} / D^{0}$ ratios measured at RHIC and the LHC. We find that including the effect of radial flow of the medium is essential for describing the enhanced $Λ_{c} / D^{0}$ ratio observed in relativistic heavy-ion collisions. We also find that the puzzling larger $Λ_{c} / D^{0}$ ratio observed in Au+Au collisions at RHIC than in Pb+Pb collisions at the LHC is due to the interplay between the effects of the QGP radial flow and the charm quark transverse momentum spectrum at hadronization. Our study further suggests that charmed hadrons have larger sizes in medium than in vacuum.
Comments:
6 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1911.00456 [pdf]
PLB(2020)·73 citations
05
[Submitted on 31 Oct 2019] (cross-list from hep-lat)
Radius of convergence in lattice QCD at finite $μ_{B}$ with rooted staggered fermions
Matteo Giordano🇭🇺 · Kornel Kapas🇭🇺 · Sandor D. Katz🇭🇺 · Daniel Nogradi🇭🇺 · Attila Pasztor🇭🇺
In typical statistical mechanical systems the grand canonical partition function at finite volume is proportional to a polynomial of the fugacity $e^{μ / T}$ . The zero of this Lee-Yang polynomial closest to the origin determines the radius of convergence of the Taylor expansion of the pressure around $μ = 0$ . The computationally cheapest formulation of lattice QCD, rooted staggered fermions, with the usual definition of the rooted determinant, does not admit such a Lee-Yang polynomial. We argue that the radius of convergence is then bounded by the spectral gap of the reduced matrix of the unrooted staggered operator. This is a cutoff effect that potentially affects all estimates of the radius of convergence with the standard staggered rooting. We suggest a new definition of the rooted staggered determinant at finite chemical potential that allows for a definition of a Lee-Yang polynomial, and, therefore of the numerical study of Lee-Yang zeros. We also describe an algorithm to determine the Lee-Yang zeros and apply it to configurations generated with the 2-stout improved staggered action at $N_{t} = 4$ . We perform a finite-volume scaling study of the leading Lee-Yang zeros and estimate the radius of convergence of the Taylor expansion extrapolated to an infinite volume. We show that the limiting singularity is not on the real line, thus giving a lower bound on the location of any possible phase transitions at this lattice spacing. In the vicinity of the crossover temperature at zero chemical potential, the radius of convergence turns out to be $μ_{B} / T \approx 2$ and roughly temperature independent. Our simulations are performed at strange quark chemical potential $μ_{s} = 0$ , but the method can be straightforwardly extended to strangeness chemical potential $μ_{S} = 0$ or strangeness neutrality.
Comments:
12 pages, 11 figures; v2: contains corrections to the formulas from the erratum PRD 104, 119901(E) (2021); results unchanged
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1911.00043 [pdf]
PRD(2020)·50 citations
06
[Submitted on 1 Nov 2019] (cross-list from astro-ph.HE)
Relativistic hybrid stars with sequential first-order phase transitions and heavy-baryon envelopes
Jia Jie Li🇩🇪 · Armen Sedrakian🇩🇪 · Mark Alford🇺🇸
We compute the mass, radius and tidal deformability of stars containing phase transitions from hadronic to quark phase(s). These quantities are computed for three types of hadronic envelopes: purely nuclear, hyperonic, and $Δ$ -resonance--hyperon admixed matter. We consider either a single first-order phase transition to a quark phase with a maximally stiff equation of state (EOS) or two sequential first-order phase transitions mimicking a transition from hadronic to a quark matter phase followed by a second phase transition to another quark phase. We explore the parameter space which produces low-mass twin and triplet configurations where equal-mass stars have substantially different radii and tidal deformabilities. We demonstrate that while for purely hadronic stiff EOS the obtained maximum mass is inconsistent with the upper limit on this quantity placed by GW170817, the inclusion of the hyperonic and $Δ$ -resonance degrees of freedom, as well as the deconfinement phase transition at sufficiently low density, produces a configuration of stars consistent with this limit. The obtained hybrid star configurations are in the mass range relevant for the interpretation of the GW170817 event. We compare our results for the tidal deformability with the limits inferred from GW170817 showing that the onset of non-nucleonic phases, such as $Δ$ -resonance--hyperon admixed phase and/or the quark phase(s), are favored by this data if the nuclear EOS is stiff. Also, we show that low-mass twins and especially triplets proliferate the number of combinations of possible types of stars that can undergo a merger event, the maximal number being six in the case of triplets. The prospects for uncovering the first-order phase transition(s) to and in quark matter via measurements of tidal deformabilities in merger events are discussed.
Comments:
11 pages, 9 figures, 5 tables; minor corrections, matches published version
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1911.00276 [pdf]
PRD(2020)·73 citations
07
[Submitted on 1 Nov 2019] (cross-list from hep-ph)
Dynamical grooming of QCD jets
Yacine Mehtar-Tani🇺🇸 · Alba Soto-Ontoso🇺🇸 · Konrad Tywoniuk🇳🇴
We propose a new class of infrared-collinear (IRC) and Sudakov safe observables with an associated jet grooming technique that removes dynamically soft and large angle branches. It is based on identifying the hardest branch in the Cambridge/Aachen re-clustering sequence and discarding prior splittings that occur at larger angles. This leads to a dynamically generated cut-off on the phase space of the tagged splitting that is encoded in a Sudakov form factor. In this exploratory study we focus on the mass and momentum sharing distributions of the tagged splitting which we analyze analytically to modified leading logarithmic accuracy and compare to Monte-Carlo simulations.
Comments:
10 pages, 11 figures. v2: included discussion on gluon-initiated jets; accepted for publication in PRD
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1911.00375 [pdf]
PRD(2020)·66 citations
08
[Submitted on 1 Nov 2019] (cross-list from astro-ph.HE)
Neutron rich matter in the laboratory and in the heavens after GW170817
C. J. Horowitz🇺🇸
The historic observations of the neutron star merger GW170817 advanced our understanding of r-process nucleosynthesis and the equation of state (EOS) of neutron rich matter. Simple neutrino physics suggests that supernovae are not the site of the main r-process. Instead, the very red color of the kilonova associated with GW170817 shows that neutron star (NS) mergers are an important r-process site. We now need to measure the masses and beta decay half-lives of very neutron rich heavy nuclei so that we can more accurately predict the abundances of heavy elements that are produced. This can be done with new radioactive beam accelerators such as the Facility for Rare Isotope Beams (FRIB). GW170817 provided information on the deformability of NS and the equation of state of dense matter. The PREX II experiment will measure the neutron skin of $^{208}$ Pb and help constrain the low density EOS. As the sensitivity of gravitational wave detectors improve, we expect to observe many more events. We look forward to exciting advances and surprises!
Comments:
12 pages, 4 figures
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1911.00411 [pdf]
Annals Phys.(2019)·34 citations
09
[Submitted on 1 Nov 2019] (cross-list from physics.chem-ph)
Systematically Improvable Tensor Hypercontraction: Interpolative Separable Density-Fitting for Molecules Applied to Exact Exchange, Second- and Third-Order Møller-Plesset Perturbation Theory
Joonho Lee · Lin Lin · Martin Head-Gordon
We present a systematically improvable tensor hypercontraction (THC) factorization based on interpolative separable density fitting (ISDF). We illustrate algorithmic details to achieve this within the framework of Becke's atom-centered quadrature grid. A single ISDF parameter $c_{ISDF}$ controls the tradeoff between accuracy and cost. In particular, $c_{ISDF}$ sets the number of interpolation points used in THC, $N_{IP} = c_{ISDF} \times N_{X}$ with $N_{X}$ being the number of auxiliary basis functions. In conjunction with the resolution-of-the-identity (RI) technique, we develop and investigate the THC-RI algorithms for cubic-scaling exact exchange for Hartree-Fock and range-separated hybrids (e.g., $ω$ B97X-V) and quartic-scaling second- and third-order Møller-Plesset theory (MP2 and MP3). These algorithms were evaluated over the W4-11 thermochemistry (atomization energy) set and A24 non-covalent interaction benchmark set with standard Dunning basis sets (cc-pVDZ, cc-pVTZ, aug-cc-pVDZ, and aug-cc-pVTZ). We demonstrate the convergence of THC-RI algorithms to numerically exact RI results using ISDF points. Based on these, we make recommendations on $c_{ISDF}$ for each basis set and method. We also demonstrate the utility of THC-RI exact exchange and MP2 for larger systems such as water clusters and $C_{20}$ . We stress that more challenges await in obtaining accurate and numerically stable THC factorization for wavefunction amplitudes as well as the space spanned by virtual orbitals in large basis sets and implementing sparsity-aware THC-RI algorithms.
Subjects:
physics.chem-ph (physics.chem-ph); Nuclear Theory (nucl-th)
arXiv:
1911.00470 [pdf]
J.Chem.Theor.Comput.(2019)·12 citations

Affiliations

first authorsco-authorsvia INSPIRE