Nuclear Theory·nucl-th

Tuesday·July 28, 2020

11 papers—6 primary·5 cross-listed

01
[Submitted on 25 Jul 2020]
Importance of Multiplicity Fluctuations in Entropy Scaling
Patrick Carzon🇺🇸 · Matthew D. Sievert🇺🇸 · Jacquelyn Noronha-Hostler🇺🇸
One of the greatest uncertainties in heavy-ion collisions is the description of the initial state. Different models predict a wide range of initial energy density distributions based on their underlying assumptions. Final flow harmonics are sensitive to these differences in the initial state due to the nearly linear mapping between eccentricities and anisotropic flow harmonics. The Trento code uses a model-agnostic approach by phenomenologically parameterizing the initial state and constraining those parameters from a Bayesian analysis. There the multiplicity fluctuations were determined by a one parameter $Γ$ distribution. However, initial-state models arising from the Color-Glass Condensate (CGC) framework lead to an initial energy density which is outside the functional form considered in Trento and its later Bayesian analyses because they rely on log-normal multiplicity fluctuations. We compare $T_{A} T_{B}$ scaling (CGC-like) to $T_{A} T_{B}$ scaling (preferred from a Trento Bayesian analysis) and find that the $T_{A} T_{B}$ form together with log-normal fluctuations is a reasonable candidate to describe the multiplicity fluctuations but leads to larger eccentricities, which would affect the extraction of viscosity in small systems.
Comments:
4 pages, 2 figures, 10th International Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2007.12977 [pdf]
PoS(2021)·5 citations
02
[Submitted on 26 Jul 2020]
Asymptotic normalization coefficient method for two-proton radiative capture
L.V. Grigorenko · Yu.L. Parfenova · N.B. Shulgina · M.V. Zhukov
The method of asymptotic normalization coefficients is a standard approach for studies of two-body non-resonant radiative capture processes in nuclear astrophysics. This method suggests a fully analytical description of the radiative capture cross section in the low-energy region of the astrophysical interest. We demonstrate how this method can be generalized to the case of three-body $2 p$ radiative captures. It was found that an essential feature of this process is the highly correlated nature of the capture. This reflects the complexity of three-body Coulomb continuum problem. Radiative capture $^{15}$ O+ $p$ + $p \to^{17}$ Ne+ $γ$ is considered as an illustration.
Comments:
9 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2007.13139 [pdf]
PLB(2020)·3 citations
03
[Submitted on 27 Jul 2020]
Trojan horse method as surrogate indirect approach to study resonant reactions in nuclear astrophysics
A. M. Mukhamedzhanov · A. S. Kadyrov · D. Y. Pang
We review the Trojan horse method and its applications to resonant reactions in nuclear astrophysics.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2007.13331 [pdf]
EPJA(2020)·10 citations
04
[Submitted on 27 Jul 2020]
Low-energy cluster vibrations in N = Z nuclei
F. Mercier🇫🇷 · A. Bjelčić🇭🇷 · T. Nikšić🇭🇷 · J.-P. Ebran🇫🇷 · E. Khan🇫🇷 · D. Vretenar🇭🇷
Significant transition strength in light $α$ -conjugate nuclei at low energy, typically below 10 MeV, has been observed in many experiments. In this work the isoscalar low-energy response of N=Z nuclei is explored using the Finite Amplitude Method (FAM) based on the microscopic framework of nuclear energy density functionals. Depending on the multipolarity of the excitation and the equilibrium deformation of a particular isotope, the low-energy strength functions display prominent peaks that can be attributed to vibration of cluster structures: $α$ + $^{12}$ C+ $α$ and $α$ + $^{16}$ O in $^{20}$ Ne, $^{12}$ C+ $^{12}$ C in $^{24}$ Mg, 4 $α$ + $^{12}$ C in $^{28}$ Si, etc. Such cluster excitations are favored in light nuclei with large deformation.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2007.13358 [pdf]
PRC(2021)·13 citations
05
[Submitted on 27 Jul 2020]
Speed of sound constraints from tidal deformability of neutron stars
A. Kanakis-Pegios · P.S. Koliogiannis · Ch.C. Moustakidis
The upper bound of the speed of sound in dense nuclear matter is one of the most interesting but still unsolved problems in Nuclear Physics. Theoretical studies in connection with recent observational data of isolated neutron stars as well as binary neutron stars systems offer an excellent opportunity to shed light on this problem. In the present work, we suggest a method to directly relate the measured tidal deformability (polarizability) of binary neutron stars system (before merger) to the maximum neutron star mass scenario and possible upper bound on the speed of sound. This method is based on the simple but efficient idea that while the upper limit of the effective tidal deformability favors soft equations of state, the recent high measured values of neutron star mass favor stiff ones. In the present work, firstly, using a simple well established model we parametrize the stiffness of the equation of state with the help of the speed of sound. Secondly, in comparison with the recent observations by LIGO/VIRGO collaboration of two events, GW170817 and GW190425, we suggest possible robust constraints. Moreover, we evaluate and postulate, in the framework of the present method, what kind of future measurements could help us to improve the stringent of the constraints on the neutron star equation of state.
Comments:
v1: 13 pages, 7 figures, 2 tables. v2: 13 pages, 7 figures, 2 tables; accepted for publication in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
arXiv:
2007.13399 [pdf]
PRC(2020)·59 citations
06
[Submitted on 27 Jul 2020]
Two-Pion-Exchange contributions to the nucleon-nucleon interactions in covariant baryon chiral perturbation theory
Yang Xiao🇨🇳 · Chun-Xuan Wang🇨🇳 · Jun-Xu Lu🇨🇳 · Li-Sheng Geng🇨🇳
Employing the covariant baryon chiral perturbation theory, we calculate the leading and next-to-leading order two-pion exchange (TPE) contributions to $N N$ interaction up to order $O (p^{3})$ . We compare the so-obtained $N N$ phase shifts with $2 \leq L \leq 6$ and mixing angles with $2 \leq J \leq 6$ with those obtained in the nonrelativistic baryon chiral perturbation theory, which allows us to check the relativistic corrections to the medium-range part of $N N$ interactions. We show that the contributions of relativistic TPE are more moderate than those of the nonrelativistic TPE. The relativistic corrections play an important role in F-waves especially the $^{3} F_{2}$ partial wave. Moreover, the relativistic results seem to converge faster than the nonrelativistic results in almost all the partial waves studied in the present work, consistent with the studies performed in the one-baryon sector.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2007.13675 [pdf]
PRC(2020)·19 citations
07
[Submitted on 24 Jul 2020] (cross-list from hep-ph)
Hadronic vacuum polarization and vector-meson resonance parameters from $e^{+} e^{-} \to π^{0} γ$
Bai-Long Hoid🇩🇪 · Martin Hoferichter🇨🇭 · Bastian Kubis🇩🇪
We study the reaction $e^{+} e^{-} \to π^{0} γ$ based on a dispersive representation of the underlying $π^{0} \to γ γ^{*}$ transition form factor. As a first application, we evaluate the contribution of the $π^{0} γ$ channel to the hadronic-vacuum-polarization correction to the anomalous magnetic moment of the muon. We find $a_{μ}^{π^{0} γ}_{\leq 1.35 GeV} = 43.8 (6) \times 1 0^{- 11}$ , in line with evaluations from the direct integration of the data. Second, our fit determines the resonance parameters of $ω$ and $ϕ$ . We observe good agreement with the $e^{+} e^{-} \to 3 π$ channel, explaining a previous tension in the $ω$ mass between $π^{0} γ$ and $3 π$ by an unphysical phase in the fit function. Combining both channels we find $M ˉ_{ω} = 782.736 (24) MeV$ and $M ˉ_{ϕ} = 1019.457 (20) MeV$ for the masses including vacuum-polarization corrections. The $ϕ$ mass agrees perfectly with the PDG average, which is dominated by determinations from the $K ˉ K$ channel, demonstrating consistency with $3 π$ and $π^{0} γ$ . For the $ω$ mass, our result is consistent but more precise, exacerbating tensions with the $ω$ mass extracted via isospin-breaking effects from the $2 π$ channel.
Comments:
10 pages, 2 figures; version published in EPJC
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2007.12696 [pdf]
EPJC(2020)·107 citations
08
[Submitted on 26 Jul 2020] (cross-list from hep-ph)
Determination of the masses and decay widths of the scalar-isoscalar and vector-isovector mesons below $2$ GeV
Evangelos Matsinos
This study revisits the issue of the extraction of estimates for the masses and for the partial decay widths to two pions of the scalar-isoscalar $I^{G} (J^{P C}) = 0^{+} (0^{++})$ and vector-isovector $I^{G} (J^{P C}) = 1^{+} (1^{--})$ mesons below $2$ GeV, from the data contained in the recent compilation by the Particle Data Group.
Comments:
Final version: 49 pages, fourteen figures, fourteen tables. Differences to the first version: changes to the text to improve readability, and to rid the manuscript of redundant sentences and of sentences which could be prone to misinterpretation/misunderstanding. No changes in any of the numbers and figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2007.13130 [pdf]
4 citations
09
[Submitted on 27 Jul 2020] (cross-list from hep-ph)
Simulating hadron test beams in liquid argon
Alexander Friedland (SLAC)🇺🇸 · Shirley Weishi Li (SLAC)🇺🇸
Thorough modeling of the physics involved in liquid argon calorimetry is essential for accurately predicting the performance of DUNE and optimizing its design and analysis pipeline. At the fundamental level, it is essential to quantify the detector response to individual hadrons---protons, charged pions, and neutrons---at different injection energies. We report such a simulation, analyzed under different assumptions about event reconstruction, such as particle identification and neutron detection. The role of event containment is also quantified. The results of this simulation can help inform the ProtoDUNE test-beam data analysis, while also providing a framework for assessing the impact of various cross section uncertainties.
Comments:
11 pages, 9 figures; conclusions unchanged; to appear in PRD
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2007.13336 [pdf]
PRD(2020)·12 citations
10
[Submitted on 27 Jul 2020] (cross-list from hep-ph)
Coherent and incoherent $J /Ψ$ photoproduction in $P b P b$ collisions at the LHC, HE -- LHC and FCC
Victor P. Goncalves🇧🇷 · Daniel E. Martins🇧🇷 · Celso R. Sena🇧🇷
The coherent and incoherent $J /Ψ$ photoproduction in $P b P b$ collisions are investigated considering the possible states of nucleon configurations in the nuclear wave function and taking into account of the non - linear corrections to the QCD dynamics. The cross sections and the rapidity and transverse momentum distributions are estimated for the energies of the next run of the LHC, High -- Energy LHC and Future Circular Collider. Our results indicate that a future experimental analysis of these processes will be useful to discriminate between different approaches for the QCD dynamics as well to improve our description of the gluon saturation effects.
Comments:
7 pages, 3 figures, 1 table
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2007.13625 [pdf]
EPJA(2021)·13 citations
11
[Submitted on 27 Jul 2020] (cross-list from astro-ph.HE)
Turbulence Fingerprint on Collective Oscillations of Supernova Neutrinos
Sajad Abbar🇩🇪
We bring to light a novel mechanism through which turbulent matter density fluctuations can induce collective neutrino flavor conversions in core-collapse supernovae, i.e., the leakage of flavor instabilities between different Fourier modes. The leakage mechanism leaves its notable fingerprint on the flavor stability of a dense neutrino gas by coupling flavor conversion modes on different scales which in turn, makes the flavor instabilities almost ubiquitous in the Fourier space. The most remarkable consequence of this effect is in that it allows for the presence of significant flavor conversions in the deepest supernova regions even in the absence of the so-called fast modes. This is yet another crucial impact of turbulence on the physics of core-collapse supernovae which can profoundly change our understanding of neutrino flavor conversions in the supernova environment.
Comments:
Minor changes to match the version accepted for publication in PRD
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2007.13655 [pdf]
PRD(2021)·19 citations

Affiliations

first authorsco-authorsvia INSPIRE