Nuclear Theory·nucl-th

Thursday·March 18, 2021

9 papers—1 primary·8 cross-listed

01
[Submitted on 17 Mar 2021]
Three-body description of $^{9}$ C: Role of low-lying resonances in breakup reactions
Jagjit Singh🇯🇵 · Takuma Matsumoto🇯🇵 · Tokuro Fukui🇯🇵 · Kazuyuki Ogata🇯🇵
The $^{9}$ C nucleus and related capture reaction, $^{8} B (p, γ)^{9} C$ , have been intensively studied with an astrophysical interest. Due to the weakly-bound nature of $^{9}$ C, its structure is likely to be described as the three-body ( $^{7} Be + p + p$ ). Its continuum structure is also important to describe reaction processes of $^{9}$ C, with which the reaction rate of the $^{8} B (p, γ)^{9} C$ process have been extracted indirectly. We perform three-body calculations on $^{9}$ C and discuss properties of its ground and low-lying states via breakup reactions. We employ the three-body model of $^{9}$ C using the Gaussian-expansion method combined with the complex-scaling method. This model is implemented in the four-body version of the continuum-discretized coupled-channels method, by which breakup reactions of $^{9}$ C are studied. The intrinsic spin of $^{7}$ Be is disregarded. By tuning a three-body interaction in the Hamiltonian of $^{9}$ C, we obtain the low-lying $2^{+}$ state with the resonant energy 0.781 MeV and the decay width 0.137 MeV, which is consistent with the available experimental information and a relatively high-lying second $2^{+}$ wider resonant state. Our calculation predicts also sole $0^{+}$ and three $1^{-}$ resonant states. We discuss the role of these resonances in the elastic breakup cross section of $^{9}$ C on $^{208}$ Pb at 65 and 160 MeV/A. The low-lying 2 $^{+}$ state is probed as a sharp peak of the breakup cross section, while the 1 $^{-}$ states enhance the cross section around 3 MeV. Our calculations will further support the future and ongoing experimental campaigns for extracting astrophysical information and evaluating the two-proton removal cross-sections.
Comments:
8 pages, 4 figures, 2 tables (final published version)
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2103.09511 [pdf]
PRC(2021)·7 citations
02
[Submitted on 19 Nov 2020] (cross-list from hep-ph)
Non-Abelian Alice strings in two-flavor dense QCD
Yuki Fujimoto🇯🇵 · Muneto Nitta
Quark-hadron continuity with two-flavor quarks that was proposed recently connects hadronic matter with neutron $^{3} P_{2}$ superfluidity and two-flavor dense quark matter. This two-flavor dense quark phase consists of the coexistence of the 2SC condensates and the $P$ -wave diquark condensates of $d$ -quarks, which gives rise to color superconductivity as well as superfluidity. We classify vortices in this phase. The most stable vortices are what we call the non-Abelian Alice strings, which are superfluid vortices with non-Abelian color magnetic fluxes therein, exhibiting so-called topological obstruction, or a non-Abelian generalization of the Alice property. We show that a single Abelian superfluid vortex is unstable against decay into three non-Abelian Alice strings. We discover that a non-Abelian Alice string carries orientational moduli of the real projective space $R P^{2}$ corresponding to the color flux therein in the presence of the $P$ -wave condensates alone. We calculate Aharanov-Bohm (AB) phases around the non-Abelian Alice string, and find that the 2SC condensates and string's orientational moduli must be aligned with each other because of single-valuedness of the AB phases of the 2SC condensates.
Comments:
14 pages, 4 figures; v2: published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Superconductivity (cond-mat.supr-con); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2011.09947 [pdf]
PRD(2021)·17 citations
03
[Submitted on 16 Mar 2021] (cross-list from nucl-ex)
New experimental $^{23}$ Na( $α, p$ ) $^{26}$ Mg Reaction Rate for Massive Star and Type-Ia Supernova models
N. J. Hubbard · C. Aa. Diget · S. P. Fox · H. O. U. Fynbo · A. M. Howard · O. S. Kirsebom · A. M. Laird · M. Munch · A. Parikh · M. Pignatari · J. R. Tomlinson
The $^{23}$ Na( $α, p$ ) $^{26}$ Mg reaction has been identified as having a significant impact on the nucleosynthesis of several nuclei between Ne and Ti in type-Ia supernovae, and of $^{23}$ Na and $^{26}$ Al in massive stars. The reaction has been subjected to renewed experimental interest recently, motivated by high uncertainties in early experimental data and in the statistical Hauser-Feshbach models used in reaction rate compilations. Early experiments were affected by target deterioration issues and unquantifiable uncertainties. Three new independent measurements instead are utilizing inverse kinematics and Rutherford scattering monitoring to resolve this. In this work we present directly measured angular distributions of the emitted protons to eliminate a discrepancy in the assumptions made in the recent reaction rate measurements, which results in cross sections differing by a factor of 3. We derive a new combined experimental reaction rate for the $^{23}$ Na( $α, p$ ) $^{26}$ Mg reaction with a total uncertainty of 30% at relevant temperatures. Using our new $^{23}$ Na( $α, p$ ) $^{26}$ Mg rate, the $^{26}$ Al and $^{23}$ Na production uncertainty is reduced to within 8%. In comparison, using the factor of 10 uncertainty previously recommended by the rate compilation STARLIB, $^{26}$ Al and $^{23}$ Na production was changing by more than a factor of 2. In type-Ia supernova conditions, the impact on production of $^{23}$ Na is constrained to within 15%.
Comments:
13 pages, 8 figures, 4 tables
Subjects:
Nuclear Experiment (nucl-ex); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
arXiv:
2103.09315 [pdf]
ApJ(2021)·2 citations
04
[Submitted on 16 Mar 2021] (cross-list from cond-mat.quant-gas)
First Principles Prediction of the Landau Parameter for Fermi Liquids near the Unitarity Limit
Shashin Pavaskar🇺🇸 · Ira Z. Rothstein🇺🇸
This paper explores the behavior of systems of cold fermions as they approach unitarity above the critical temperature. As we move away from unitarity, by decreasing the scattering length, the dilaton, the Goldstone boson resulting from the spontaneous breaking of Schrodinger symmetry by the Fermi sea, becomes gapped. At energies below this gap, the interaction between quasi-particles will be dominated by local interactions generated by off-shell dilaton exchange. The dilaton mass can, in turn, be related via anomaly matching, to the scattering length and contact parameter within the confines of a systematic expansion. We use this relation to predict the s-wave Landau parameter to be $f = \frac{4 π a ( 2 ϵ ( p _{F} ) - p _{F}^{2} / m _{⋆} ) ^{2} m}{3 p _{F}^{4} C ~ ( a )}$ where $a$ is the scattering length, $m$ the atomic mass, $m_{⋆}$ , the effective mass which can be extracted from heat capacity, and $C ~ (a)$ is the dimensionless contact parameter. The range of validity of this prediction (given in eq.(21)) is determined by the value of contact parameter and Fermi velocity, which depend upon the scattering length. It is expected to be valid in a range above $k_{F} a \sim 1$ , but the actual window will depend upon the values of aforementioned parameters. Given this result for $f$ , we predict the compressibility, spin susceptibility and the quasi-particle life-time.
Comments:
This replacement contains an improved discussion of the range of validity of the EFT and includes a prediction for the spin susceptibility of the Fermi gas. It also fixes an error in the prediction for the Landau parameter and the compressibility in the earlier version
Subjects:
Quantum Gases (cond-mat.quant-gas); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2103.09339 [pdf]
PRB(2022)·6 citations
05
[Submitted on 17 Mar 2021] (cross-list from astro-ph.HE)
Sensitivity of Neutron-Rich Nuclear Isomer Behavior to Uncertainties in Direct Transitions
G. Wendell Misch · Trevor M. Sprouse · Matthew R. Mumpower · Aaron Couture · Chris L. Fryer · Bradley S. Meyer · Yang Sun
Nuclear isomers are populated in the rapid neutron capture process (r process) of nucleosynthesis. The r process may cover a wide range of temperatures, potentially starting from several tens of GK (several MeV) and then cooling as material is ejected from the event. As the r-process environment cools, isomers can freeze out of thermal equilibrium or be directly populated as astrophysical isomers (astromers). Two key behaviors of astromers -- ground state<->isomer transition rates and thermalization temperatures -- are determined by direct transition rates between pairs of nuclear states. We perform a sensitivity study to constrain the effects of unknown transitions on astromer behavior. We also introduce a categorization of astromers that describes their potential effects in hot environments. We provide a table of neutron-rich isomers that includes the astromer type, thermalization temperature, and key unmeasured transition rates.
Comments:
52 pages, 13 figures, 2 tables
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2103.09392 [pdf]
Symmetry(2021)·21 citations
06
[Submitted on 17 Mar 2021] (cross-list from hep-lat)
Parton physics from a heavy-quark operator product expansion: Formalism and Wilson coefficients
William Detmold🇺🇸 · Anthony V. Grebe🇺🇸 · Issaku Kanamori🇯🇵 · C.-J. David Lin🇹🇼 · Robert J. Perry🇹🇼 · Yong Zhao🇺🇸
Parton distribution functions (PDFs) and light-cone distribution amplitudes (LCDAs) are central non-perturbative objects of interest in high-energy inelastic and elastic scattering, respectively. As a result, an ab-initio determination of these objects is highly desirable. In this paper we present theoretical details for the calculation of the PDFs and LCDAs using a heavy-quark operator product expansion method. This strategy was proposed in a previous paper [Phys. Rev. D 73, 014501 (2006)] for computing higher moments of the PDFs using lattice QCD. Its central feature is the introduction of a fictitious, valence heavy quark. In the current article, we show that the operator product expansion (OPE) of the hadronic matrix element we study can also be expressed as the convolution of a perturbative matching kernel and the corresponding light-cone distribution, which in principle can be inverted to determine the parton momentum fraction dependence. Regarding the extraction of higher moments, this work also provides the one-loop Wilson coefficients in the OPE formulas for the unpolarized PDF, helicity PDF and pseudo-scalar meson LCDAs. Although these Wilson coefficients for the PDFs can be inferred from existing results in the literature, those for the LCDAs are new.
Comments:
22 pages, 3 figures; Text updated to be consistent with published version
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2103.09529 [pdf]
PRD(2021)·54 citations
07
[Submitted on 17 Mar 2021] (cross-list from hep-ph)
Hadronic Rescattering in pA and AA Collisions
Christian Bierlich🇸🇪 · Torbjörn Sjöstrand🇸🇪 · Marius Utheim🇸🇪
In a recent article we presented a model for hadronic rescattering, and some results were shown for pp collisions at LHC energies. In order to extend the studies to pA and AA collisions, the Angantyr model for heavy-ion collisions is taken as the starting point. Both these models are implemented within the general-purpose Monte Carlo event generator Pythia, which makes the matching reasonably straightforward, and allows for detailed studies of the full space--time evolution. The rescattering rate is significantly higher than in pp, especially for central AA collisions, where the typical primary hadron rescatters several times. We study the impact of rescattering on a number of distributions, such as pT and eta spectra, and the space--time evolution of the whole collision process. Notably rescattering is shown to give a significant contribution to elliptic flow in XeXe and PbPb, and to give a nontrivial impact on charm production.
Comments:
38 pages, 16 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2103.09665 [pdf]
EPJA(2021)·46 citations
08
[Submitted on 17 Mar 2021] (cross-list from hep-ph)
Mass spectra of $N Ω$ dibaryons in the $^{3} S_{1}$ and $^{5} S_{2}$ channels
Xiao-Hui Chen🇨🇳 · Qi-Nan Wang🇨🇳 · Wei Chen🇨🇳 · Hua-Xing Chen🇨🇳
We study the mass spectra of the $N Ω$ dibaryons in the $^{3} S_{1}$ and $^{5} S_{2}$ channels with $J^{P} = 1^{+}$ and $2^{+}$ respectively, by using the method of QCD sum rules. We construct two dibaryon interpolating currents in the molecular picture and calculate their correlation functions and spectral densities up to dimension-16 condensates. Our results indicate that there may exist an $N Ω$ dibaryon bound state in the $^{5} S_{2}$ channel with a binding energy of about $21 MeV$ . The masses of the $^{3} S_{1}$ $N Ω$ dibaryons with $J^{P} = 1^{+}$ are predicted to be higher than the $N Ω$ and $ΛΞ$ thresholds, and thus can decay into these final states directly in S-wave. The $N Ω (^{5} S_{2})$ dibaryon bound state can decay into the octet-octet final states $ΛΞ$ and $ΣΞ$ in D-wave via the quark rearrangement mechanism. The existence of these $N Ω$ dibaryons may be identified in the relativistic heavy-ion collision experiments in the future.
Comments:
9 pages, 5 figures. Published in Physical Review D
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2103.09739 [pdf]
PRD(2021)·15 citations
09
[Submitted on 17 Mar 2021] (cross-list from hep-ph)
TMDlib2 and TMDplotter: a platform for 3D hadron structure studies
N.A. Abdulov🇷🇺 · A. Bacchetta🇮🇹 · S. Baranov🇷🇺 · A. Bermudez Martinez🇩🇪 · V. Bertone🇫🇷 · C. Bissolotti🇮🇹 · V. Candelise🇮🇹 · L.I. Estevez Banos🇩🇪 · M. Bury🇩🇪 · P.L.S. Connor🇩🇪 · L. Favart🇧🇪 · F. Guzman🇨🇺 and 26 other authors
A common library, TMDlib2, for Transverse-Momentum-Dependent distributions (TMDs) and unintegrated parton distributions (uPDFs) is described, which allows for easy access of commonly used TMDs and uPDFs, providing a three-dimensional (3D) picture of the partonic structure of hadrons. The tool TMDplotter allows for web-based plotting of distributions implemented in TMDlib2, together with collinear pdfs as available in LHAPDF.
Comments:
18 pages, 3 figures. Updated with version published in EPJC
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2103.09741 [pdf]
EPJC(2021)·100 citations

Affiliations

first authorsco-authorsvia INSPIRE