Nuclear Theory·nucl-th

Friday·November 1, 2019

12 papers—5 primary·7 cross-listed

01
[Submitted on 30 Oct 2019]
Indirect methods in nuclear astrophysics with relativistic radioactive beams
Thomas Aumann🇩🇪 · Carlos A. Bertulani🇩🇪
Reactions with radioactive nuclear beams at relativistic energies have opened new doors to clarify the mechanisms of stellar evolution and cataclysmic events involving stars and during the big bang epoch. Numerous nuclear reactions of astrophysical interest cannot be assessed directly in laboratory experiments. Ironically, some of the information needed to describe such reactions, at extremely low energies (e.g., keVs), can only be studied on Earth by using relativistic collisions between heavy ions at GeV energies. In this contribution, we make a short review of experiments with relativistic radioactive beams and of the theoretical methods needed to understand the physics of stars, adding to the knowledge inferred from astronomical observations. We continue by introducing a more detailed description of how the use of relativistic radioactive beams can help to solve astrophysical puzzles and several successful experimental methods. State-of-the-art theories are discussed at some length with the purpose of helping us understand the experimental results reported. The review is not complete and we have focused most of it to traditional methods aiming at the determination of the equation of state of symmetric and asymmetric nuclear matter and the role of the symmetry energy. Whenever possible, under the limitations of our present understanding of experimental data and theory, we try to pinpoint the information still missing to further understand how stars evolve, explode, and how their internal structure might be.
Comments:
70 pages, 66 figures, 458 references. 1 more figure and new references added
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex)
arXiv:
1910.14094 [pdf]
PPNP(2020)·22 citations
02
[Submitted on 30 Oct 2019]
Prospects of Event Shape Sorting
Boris Tomasik · Jakub Cimerman
Event Shape Sorting is a novel method which is devised to organise a sample of collision events in such a way, that events with similar final state distribution of hadrons end up sorted close to each other. Such events are likely to have evolved similarly. Thus the method allows to focus at finer features of the collision evolution because it would allow for averages over similar events that do not wash away these features. The algorithm is shortly explained. We also point out the distinction of Event Shape Sorting from the well established technique of Event Shape Engineering.
Comments:
Proceedings of WPCF 2019, June 3-7, Dubna, Russia. We put colored version of the figures on the arxiv (only BW in the printed proceedings)
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1910.14183 [pdf]
Phys.Part.Nucl.(2020)·0 citations
03
[Submitted on 31 Oct 2019]
Muonic Lithium atoms: nuclear structure corrections to the Lamb shift
S. Li Muli🇩🇪 · A. Poggialini🇮🇹 · S. Bacca🇩🇪
In view of the future plans to measure the Lamb shift in muonic Lithium atoms we address the microscopic theory of the $μ$ - $^{6}$ Li $^{2 +}$ and $μ$ - $^{7}$ Li $^{2 +}$ systems. The goal of the CREMA collaboration is to measure the Lamb shift to extract the charge radius with high precision and compare it to electron scattering data or atomic spectroscopy to see if interesting puzzles, such as the proton and deuteron radius puzzles, arise. For this experiment to be successful, theoretical information on the nuclear structure corrections to the Lamb shift is needed. For $μ$ - $^{6}$ Li $^{2 +}$ and $μ$ - $^{7}$ Li $^{2 +}$ there exist only estimates of nuclear structure corrections based on experimental data that suffer from very large uncertainties. We present the first steps towards an ab initio computation of these quantities using few-body techniques.
Comments:
Submission to SciPost, 10 pages, 4 figure, Proceedins of the 24th European conference on few-body problems in physics (EFB24) at the University of Surrey, Guildford, United Kingdom, from 2 to 6 September 2019
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1910.14370 [pdf]
SciPost Phys.Proc.(2020)·9 citations
04
[Submitted on 31 Oct 2019]
Rapidity-dependent eccentricity scaling in relativistic heavy-ion collisions
Rodrigo Franco🇧🇷 · Matthew Luzum🇧🇷
There is a well-established relation between the spatial asymmetry in the initial stage of a heavy-ion collision and the final momentum anisotropy, which allows for a separation of effects from initial conditions vs. later evolution and has proved exceptionally powerful. However, until recently it has only been studied in two dimensions -- either through boost-invariant simulations or studying only quantities at mid-rapidity. We explore an extension to 3 dimensions, in order to determine whether a similar understanding can be obtained for the rapidity dependence of the collision system. In particular, we introduce rapidity-dependent eccentricities and investigate a trivial extension of the 2D eccentricity scaling of elliptic and triangular flow, as well as a way to systematically improve these initial-state estimators. We then explore the dependence of the resulting response coefficients on shear viscosity and initial total energy.
Comments:
7 pages, 10 figures; v2: addition of Appendix B with discussion about another possible term in gradient expansion of eccentricities, version accepted for publication
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1910.14598 [pdf]
PLB(2020)·12 citations
05
[Submitted on 31 Oct 2019]
Searching for three-nucleon short-range correlations
Misak M. Sargsian🇺🇸 · Donal B. Day🇺🇸 · Leonid L. Frankfurt🇮🇱 · Mark I. Strikman🇺🇸
Three nucleon short range correlations~(SRCs) are one of the most elusive structures in nuclei. Their observation and the subsequent study of their internal makeup will have a significant impact on our understanding of the dynamics of super-dense nuclear matter which exists at the cores of neutron stars. We discuss the kinematic conditions and observables that are most favorable for probing 3N-SRCs in inclusive electro-nuclear processes and make a prediction for a quadratic dependence of the probabilities of finding a nucleon in 2N- and 3N- SRCs. We demonstrate that this prediction is consistent with the limited high energy experimental data available, suggesting that we have observed, for the first time, 3N-SRCs in electro-nuclear processes. Our analysis enables us to extract $a_{3} (A, Z)$ , the probability of finding 3N-SRCs in nuclei relative to the A=3 system.
Comments:
7 pages and 4 figures, to be published in Physical Review C
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1910.14663 [pdf]
PRC(2019)·16 citations
06
[Submitted on 30 Oct 2019] (cross-list from hep-ph)
The Soft Quark Sudakov
Ian Moult🇺🇸 · Iain W. Stewart🇺🇸 · Gherardo Vita🇺🇸 · Hua Xing Zhu🇨🇳
There has been recent interest in understanding the all loop structure of the subleading power soft and collinear limits, with the goal of achieving a systematic resummation of subleading power infrared logarithms. Most of this work has focused on subleading power corrections to soft gluon emission, whose form is strongly constrained by symmetries. In this paper we initiate a study of the all loop structure of soft fermion emission. In $N = 1$ QCD we perform an operator based factorization and resummation of the associated infrared logarithms, and prove that they exponentiate into a Sudakov due to their relation to soft gluon emission. We verify this result through explicit calculation to $O (α_{s}^{3})$ . We show that in QCD, this simple Sudakov exponentiation is violated by endpoint contributions proportional to $(C_{A} - C_{F})^{n}$ which contribute at leading logarithmic order. Combining our $N = 1$ result and our calculation of the endpoint contributions to $O (α_{s}^{3})$ , we conjecture a result for the soft quark Sudakov in QCD, a new all orders function first appearing at subleading power, and give evidence for its universality. Our result, which is expressed in terms of combinations of cusp anomalous dimensions in different color representations, takes an intriguingly simple form and also exhibits interesting similarities to results for large-x logarithms in the off diagonal splitting functions.
Comments:
21 pages, many beautiful figures. v2: journal version, added appendices
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1910.14038 [pdf]
JHEP(2020)·77 citations
07
[Submitted on 30 Oct 2019] (cross-list from hep-ph)
The Myriad Uses of Instantons
Robert D. Pisarski🇺🇸 · Fabian Rennecke🇺🇸
In quantum chromodynamics (QCD), the role which topologically non-trivial configurations play in splitting the singlet pseudo-Goldstone meson, the $η^{'}$ , from the octet is familiar. In addition, such configurations contribute to other processes which violate the axial $U (1)_{A}$ symmetry. While the nature of topological fluctuations in the confined phase is still unsettled, at temperatures well above that for the chiral phase transition, they can be described by a dilute gas of instantons. We show that instantons of arbitrary topological charge $Q$ generate anomalous interactions between $2 N_{f} ∣ Q ∣$ quarks, which for $Q = 1$ make the $η^{'}$ heavy. For two flavors we compute an anomalous quartic meson coupling and discuss its implications for the phenomenology of the chiral phase transition. A dilute instanton gas suggests that for cold, dense quarks, instantons do not evaporate until very high densities, when the baryon chemical potential is $≳ 2$ GeV.
Comments:
4+21 pages; v2: details on the ADHM construction added
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1910.14052 [pdf]
PRD(2020)·26 citations
08
[Submitted on 30 Oct 2019] (cross-list from nucl-ex)
Invariant-mass spectroscopy of $^{14}$ O excited states
R.J. Charity🇺🇸 · K.W. Brown🇺🇸 · J. Okolowicz🇵🇱 · M. Ploszajczak🇫🇷 · J.E. Elson🇺🇸 · W. Reviol🇺🇸 · L.G. Sobotka🇺🇸 · W.W. Buhro🇺🇸 · Z. Chajecki🇺🇸 · W.G. Lynch🇺🇸 · J. Manfredi🇺🇸 · R. Shane🇺🇸 and 6 other authors
Excited states in $^{14}$ O have been investigated both experimentally and theoretically. Experimentally, these states were produced via neutron-knockout reactions with a fast $^{15}$ O beam and the invariant-mass technique was employed to isolate the 1 $p$ and 2 $p$ decay channels and determine their branching ratios. The spectrum of excited states was also calculated with the Shell Model Embedded in the Continuum that treats bound and scattering states in a unified model. By comparing energies, widths and decay branching patterns, spin and parity assignments for all experimentally observed levels below 8 MeV are made. This includes the location of the second 2 $^{+}$ state that we find is in near degeneracy with the third 0 $^{+}$ state. An interesting case of sequential 2 $p$ decay through a pair of degenerate $^{13}$ N excited states with opposite parities was found where the interference between the two sequential decay pathways produces an unusual relative-angle distribution between the emitted protons.
Comments:
19 pages, 20 figures
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1910.14100 [pdf]
PRC(2019)·19 citations
09
[Submitted on 31 Oct 2019] (cross-list from hep-ph)
Prediction of $N Ω$ -like dibaryons with heavy quarks
Hongxia Huang🇨🇳 · Jialun Ping🇨🇳 · Fan Wang🇨🇳
Possible $N Ω$ -like dibaryons $N Ω_{ccc}$ and $N Ω_{bbb}$ with quantum numbers $I J^{P} = \frac{1}{2} 2^{+}$ are investigated within the framework of quark delocalization color screening model. We find both of these two states are bound, and the binding energy increases as the quarks of the system become heavier. The attraction between $N$ and $Ω_{ccc}$ (or $Ω_{bbb}$ ) mainly comes from the kinetic energy term due to quark delocalization and color screening. The effect of the channel-coupling provides more effective attraction to $N Ω_{ccc}$ and $N Ω_{bbb}$ systems. Besides, the scattering length, the effective range, and the binding energy, obtained from the calculation of the low-energy scattering phase shifts, also supports the existence of the $N Ω_{ccc}$ and $N Ω_{bbb}$ states. All these properties can provide necessary information for experimental search for the $N Ω$ -like dibaryons with heavy quarks. And the experimental progress can also check the mechanism of the intermediate-range attraction of the baryon-baryon interaction in quark models.
Comments:
6 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1910.14277 [pdf]
PRC(2020)·15 citations
10
[Submitted on 31 Oct 2019] (cross-list from hep-ph)
Probing QCD critical fluctuations from the yield ratio of strange hadrons in relativistic heavy-ion collisions
Tianhao Shao🇨🇳 · Jinhui Chen🇨🇳 · Che Ming Ko🇺🇸 · Kai-Jia Sun🇺🇸
By analyzing the available data on strange hadrons in central Pb+Pb collisions from the NA49 Collaboration at the Super Proton Synchrotron (SPS) and in central Au+Au collisions from the STAR Collaboration at the Relativistic Heavy-Ion Collider (RHIC) in a wide collision energy range from $s_{NN}$ = 6.3 GeV to 200 GeV, we find a possible non-monotonic behavior in the ratio $\mathcal{O}_\text{K-$ \Xi $-$ \phi $-$ \Lambda $}$ = $\frac{N ( K ^{+} ) N ( Ξ ^{-} )}{N ( ϕ ) N ( Λ )}$ of $K^{+}$ , $Ξ^{-}$ , $ϕ$ , and $Λ$ yields as a function of $s_{NN}$ . Based on the quark coalescence model, which can take into account the effect of quark density fluctuations on hadron production, a possible non-monotonic behavior in the dependence of the strange quark density fluctuation on $s_{N N}$ is obtained. This is in contrast to the coalescence model that does not include quark density fluctuations and also to the statistical hadronization model as both fail to describe even qualitatively the collision energy dependence of the ratio $\mathcal{O}_\text{K-$ \Xi $-$ \phi $-$ \Lambda $}$ . Our findings thus suggest that the signal and location of a possible critical endpoint in the QCD phase diagram, which is expected to result in large quark density fluctuations, can be found in the on-going Bean Energy Scan program at RHIC.
Comments:
7 pages, 3 tables and 1 figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1910.14281 [pdf]
PLB(2020)·15 citations
11
[Submitted on 31 Oct 2019] (cross-list from hep-ph)
Neutron-antineutron oscillations in the deuteron studied with $N N$ and $N ˉ N$ interactions based on chiral effective field theory
Johann Haidenbauer🇩🇪 · Ulf-G. Meißner🇩🇪
Neutron-antineutron ( $n - n ˉ$ ) oscillations in the deuteron are considered. Specifically, the deuteron lifetime is calculated in terms of the free-space $n - n ˉ$ oscillation time $τ_{n - n ˉ}$ based on $N N$ and $N ˉ N$ interactions derived within chiral effective field theory (EFT). This results in $(2.6 \pm 0.1) \times 1 0^{22} τ_{n - n ˉ}^{2}$ s, which is close to the value obtained by Dover and collaborators more than three decades ago, but disagrees with recent EFT calculations that were performed within the perturbative scheme proposed by Kaplan, Savage, and Wise. Possible reasons for the difference are discussed.
Comments:
5 pages, 1 figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1910.14423 [pdf]
CPC(2020)·23 citations
12
[Submitted on 31 Oct 2019] (cross-list from hep-ph)
Blast-wave description of $Υ$ elliptic flow at energies available at the CERN Large Hadron Collider
Klaus Reygers🇩🇪 · Alexander Schmah🇩🇪 · Anastasia Berdnikova🇷🇺 · Xu Sun🇺🇸
A simultaneous blast-wave fit to particle yields and elliptic flow ( $v_{2}$ ) measured as a function of transverse momentum in Pb-Pb collisions at LHC energies is presented. A compact formula for the calculation of $v_{2} (p_{T})$ for an elliptic freeze-out surface is used which follows from the Cooper-Frye ansatz without further assumptions. Over the full available $p_{T}$ range, the $Υ$ elliptic flow data is described by the prediction based on the fit to lighter particles. This prediction shows that, due to the large $Υ$ mass, a sizable elliptic flow is only expected at transverse momenta above 10 GeV/ $c$ .
Comments:
9 pages, 5 figures, published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1910.14618 [pdf]
PRC(2020)·23 citations

Affiliations

first authorsco-authorsvia INSPIRE