Nuclear Theory·nucl-th

Thursday·November 24, 2022

10 papers—4 primary·6 cross-listed

01
[Submitted on 22 Nov 2022]
Special point "trains" in the M-R diagram of hybrid stars
David Blaschke🇵🇱 · Alexander Ayriyan🇦🇲 · Mateusz Cierniak🇵🇱 · Ana Gabriela Grunfeld🇦🇷 · Oleksii Ivanytskyi🇵🇱 · Mahboubeh Shahrbaf🇵🇱
We present a systematic investigation of the possible locations for the special point (SP), a unique feature of hybrid neutron stars in the mass-radius diagram. The study is performed within the two-phase approach where the high-density (quark matter) phase is described by the covariant nonlocal Nambu--Jona-Lasinio (nlNJL) model equation of state (EOS) which is shown to be equivalent to a constant-sound-speed (CSS) EOS. For the nuclear matter phase around saturation density different relativistic density functional EOSs are used: DD2p00, its excluded-volume modification DD2p40 and the hypernuclear EOS DD2Y-T. In the present contribution we apply the Maxwell construction scheme for the deconfinement transition and demonstrate that a simultaneous variation of the vector and diquark coupling constants results in the occurrence of SP "trains" which are invariant against changing the nuclear matter EOS. We propose that the SP train corresponding to a variation of the diquark coupling at constant vector coupling is special since it serves as a lower bound for the line of maximum masses and accessible radii of massive hybrid stars.
Comments:
8 pages, 5 figures, Contribution to Proceedings of Quark Confinement and the Hadron Spectrum XV, August 1-6, 2022, Stavanger, Norway
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2211.12626 [pdf]
EPJ Web Conf.(2022)·3 citations
02
[Submitted on 23 Nov 2022]
Probing the size and binding energy of the hypertriton in heavy ion collisions
C.A. Bertulani🇺🇸
The hypertriton is predicted to have a small binding energy (a weighted average of about 150 keV), consistent with a large matter radius (~ 10 fm), larger than the historical 11Li halo discovered more than 35 years ago. But the reported experimental values of the binding energy of the hypertriton range from 70 to 400 keV. In this work I discuss the electromagnetic response and interaction radius of the hypertriton and how high energy heavy ion collisions (~ 1 - 2 GeV/nucleon) can help achieving a higher accuracy for the determination of its size and binding energy.
Comments:
8 pages, 10 figures, Phys. Lett B, accepted
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex)
arXiv:
2211.12643 [pdf]
PLB(2023)·12 citations
03
[Submitted on 23 Nov 2022]
Early deconfinement of asymptotically conformal color-superconducting quark matter in neutron stars
Oleksii Ivanytskyi🇵🇱 · David Blaschke🇵🇱 · Tobias Fischer🇵🇱 · Andreas Bauswein🇩🇪
We present a relativistic density functional approach to color superconducting quark matter that mimics quark confinement by a fast growth of the quasiparticle selfenergy in the confining region. The approach is shown to be equivalent to a chiral model of quark matter with medium dependent couplings. While the (pseudo)scalar sector of the model is fitted to the vacuum phenomenology of quantum chromodynamics, the strength of interaction in the vector and diquark channels is varied in order to provide the best agreement with the observational constraints on the mass-radius relation and tidal deformability of neutron stars modelled with our approach. In order to recover the conformal behavior of quark matter at asymptotically high densities we introduce a medium dependence of the vector and diquark couplings motivated by the nonperturbative gluon exchange. Our analysis signals that the onset of deconfinement to color superconducting quark matter is likely to occur in neutron stars with masses below 1.0 $M_{⊙}$ .
Comments:
8 pages, 4 figuures, Contribution to Proceedings of Quark Confinement and the Hadron Spectrum XV, August 1-6, 2022, Stavanger, Norway
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2211.12730 [pdf]
EPJ Web Conf.(2022)·2 citations
04
[Submitted on 23 Nov 2022]
Radial Oscillations of Dark Matter admixed Neutron Stars
Pinku Routray · H. C. Das · Souhardya Sen · Bharat Kumar · Grigoris Panotopoulos · Tianqi Zhao
Within the relativistic mean-field model, we investigate the properties of dark matter (DM) admixed neutron stars, considering non-rotating objects made of isotropic matter. We adopt the IOPB-I hadronic equation of state (EOS) by assuming that the fermionic DM within super-symmetric models has already been accreted inside the neutron star (NS). The impact of DM on the mass-radius relationships and the radial oscillations of pulsating DM admixed neutron stars (with and without the crust) are explored. It is observed that the presence of DM softens the EOS, which in turn lowers the maximum mass and its corresponding radius. Moreover, adding DM results in higher frequencies of pulsating objects and hence we show the linearity of fundamental mode frequency of canonical NS with DM Fermi momentum. We also investigate the profile of eigenfunctions solving the Sturm-Liouville boundary value problem, and verify its validity. Further, we study the stability of NSs considering the fundamental mode frequency variation with the mass of the star, and verify the stability criterion $\partial M / \partial ρ_{c} > 0$ . Finally, the effect of the crust on the large frequency separation for different DM Fermi momenta is shown as well.
Comments:
Published in Phys. Rev. D 107, 103039 (2023)
Subjects:
Nuclear Theory (nucl-th); General Relativity and Quantum Cosmology (gr-qc)
arXiv:
2211.12808 [pdf]
PRD(2023)·50 citations
05
[Submitted on 22 Nov 2022] (cross-list from hep-ph)
Width effects of broad new resonances in loop observables and application to $(g - 2)_{μ}$
Andreas Crivellin🇨🇭 · Martin Hoferichter🇨🇭
In the phenomenology of strong interactions most physical states acquire a substantial width, and thus can only be defined in a model-independent way by pole positions and residues of the $S$ -matrix. This information is incorporated in the Källén-Lehmann representation, whose spectral function characterizes the shape of the resonance and can be constrained by the dominant decay channels. Here, we argue that similar effects become important whenever beyond-the-Standard-Model particles possess a sizable decay width - as possible for instance in cases with a large branching fraction to a dark sector or strongly coupled scenarios - and show how their widths can be incorporated in the calculation of loop observables. As an application, we consider the anomalous magnetic moment of the muon, including both the direct effect of new physics and the possible indirect impact of a broad light $Z^{'}$ on $e^{+} e^{-} \to hadrons$ cross sections. Throughout, we provide results for a general spectral function and its reconstruction from the one-loop imaginary part, where the latter captures the leading two-loop effects.
Comments:
13 pages, 4 figures; journal version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2211.12516 [pdf]
PRD(2023)·29 citations
06
[Submitted on 22 Nov 2022] (cross-list from hep-ph)
Schwinger mechanism for gluons from lattice QCD
A. C. Aguilar🇧🇷 · F. De Soto🇪🇸 · M. N. Ferreira🇪🇸 · J. Papavassiliou🇪🇸 · F. Pinto-Gómez🇪🇸 · C. D. Roberts🇨🇳 · J. Rodríguez-Quintero🇪🇸
Continuum and lattice analyses have revealed the existence of a mass-scale in the gluon two-point Schwinger function. It has long been conjectured that this expresses the action of a Schwinger mechanism for gauge boson mass generation in quantum chromodynamics (QCD). For such to be true, it is necessary and sufficient that a dynamically-generated, massless, colour-carrying, scalar gluon+gluon correlation emerge as a feature of the dressed three-gluon vertex. Working with results on elementary Schwinger functions obtained via the numerical simulation of lattice-regularised QCD, we establish with an extremely high level of confidence that just such a feature appears; hence, confirm the conjectured origin of the gluon mass scale.
Comments:
8 pages, 8 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2211.12594 [pdf]
PLB(2023)·37 citations
07
[Submitted on 23 Nov 2022] (cross-list from hep-ph)
Subleading power corrections to heavy quarkonium production in QCD factorization approach
Kyle Lee🇺🇸 · Jian-Wei Qiu🇺🇸 · George Sterman🇺🇸 · Kazuhiro Watanabe🇫🇷
We report the current understanding of heavy quarkonium production at high transverse momentum ( $p_{T}$ ) in hadronic collisions in terms of QCD factorization. In this presentation, we highlight the role of subleading power corrections to heavy quarkonium production, which are essential to describe the $p_{T}$ spectrum of quarkonium at a relatively lower $p_{T}$ . We also introduce prescription to match QCD factorization to fixed-order NRQCD factorization calculations for quarkonium production at low $p_{T}$ .
Comments:
8 pages, 4 figures; talk given at the XVth Quark confinement and the Hadron spectrum conference, August 1st - 6th, 2022, University of Stavanger, Norway
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2211.12648 [pdf]
EPJ Web Conf.(2022)·5 citations
08
[Submitted on 23 Nov 2022] (cross-list from nucl-ex)
Spin polarization and alignment in heavy-ion collisions
Subhash Singha🇨🇳
We report the measurements of global spin polarization of hyperons ( $P_{Λ}$ ) from FAIR, RHIC and LHC energies. The $P_{Λ}$ continue to follow an increasing trend at $s_{N N}$ < 7.7 GeV indicating that enormous vorticity prevail even in hadronic dominant region. New measurements of local spin polarization ( $P_{z, 2}$ ) from isobar collisions follow the same pattern observed in previous RHIC and LHC energies. An observable motivated by predicted baryonic Spin Hall Effect, the net local polarization ( $P_{z, 2}^{net}$ ), shows negative value in Au+Au collisions at $s_{N N}$ = 19.6 and 27 GeV. The first $P_{z}$ measurement with respect to third order harmonic in 200 GeV RHIC isobar collisions show a non-zero sine modulation, indicating the presence of complex vortical structure in the medium. Surprising new patterns of spin alignment ( $ρ_{00}$ ) for various vector mesons ( $K^{* 0}$ , $K^{*\pm}$ , $ϕ$ and $J / ψ$ ) emerged at both RHIC and LHC energies. The large deviation in $ρ_{00}$ of several species poses challenge to the theory.
Comments:
SQM 2022 proceedings
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2211.13155 [pdf]
EPJ Web Conf.(2023)·2 citations
09
[Submitted on 23 Nov 2022] (cross-list from hep-ph)
Phase transition amplification of proton number fluctuations in nuclear collisions from a transport model approach
O. Savchuk🇺🇸 · R. V. Poberezhnyuk🇺🇦 · A. Motornenko🇩🇪 · J. Steinheimer🇩🇪 · M. I. Gorenstein🇺🇦 · V. Vovchenko🇺🇸
The time evolution of particle number fluctuations in nuclear collisions at intermediate energies ( $E_{lab} = 1.23 - 10 A$ GeV) is studied by means of the UrQMD-3.5 transport model. The transport description incorporates baryonic interactions through a density-dependent potential. This allows for an implementation of a first order phase transition including a mechanically unstable region at large baryon density. The scaled variance of the baryon and proton number distributions is calculated in the central cubic spatial volume of the collisions at different times. A significant enhancement of fluctuations associated with the unstable region is observed. This enhancement persists to late times reflecting a memory effect for the fluctuations. The presence of the phase transition has a much smaller influence on the observable event-by-event fluctuations of protons in momentum space.
Comments:
9 pages, 6 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2211.13200 [pdf]
PRC(2023)·14 citations
10
[Submitted on 23 Nov 2022] (cross-list from hep-ph)
Transverse-momentum-dependent factorization at next-to-leading power
Leonard Gamberg🇺🇸 · Zhong-Bo Kang🇺🇸 · Ding Yu Shao🇨🇳 · John Terry🇺🇸 · Fanyi Zhao🇺🇸
We study transverse momentum dependent factorization and resummation at sub-leading power in Drell-Yan and semi-inclusive deep inelastic scattering. In these processes the sub-leading power contributions to the cross section enter as a kinematic power correction to the leptonic tensor, and the kinematic, intrinsic, and dynamic sub-leading contributions to the hadronic tensor. By consistently treating the power counting of the interactions, we demonstrate renormalization group consistency. We calculate the anomalous dimensions of the kinematic and intrinsic sub-leading correlation functions at one loop and find that the evolution equations give rise to anomalous dimension matrices which mix leading and sub-leading power distribution functions. Additionally we calculate the hard and soft functions associated with each of these contributions. We find that these hard and soft contributions differ from those at the leading power. Finally, we calculate the rapidity anomalous dimension for the dynamic sub-leading distributions and find that it is the same as the leading power anomalous dimension. We then comment on the implications for the soft function associated with this contribution. Using this information, we establish the factorization formalism at sub-leading power for these processes at the one-loop level.
Comments:
60 pages, 15 figures. In this update, we added additional clarification and discussion in the introduction and conclusion
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2211.13209 [pdf]
30 citations

Affiliations

first authorsco-authorsvia INSPIRE