Nuclear Theory·nucl-th

Friday·January 1, 2021

16 papers—8 primary·8 cross-listed

09
[Submitted on 29 Dec 2020] (cross-list from hep-ph)
New fit of time-like proton electromagnetic form factors from $e^{+} e^{-}$ colliders
Egle Tomasi-Gustafsson🇫🇷 · Andrea Bianconi🇮🇹 · Simone Pacetti🇮🇹
The data on the proton form factors in the time-like region from the BaBar, BESIII and CMD-3 Collaborations are examined to have coherent pieces of information on the proton structure. Oscillations in the annihilation cross section, previously observed, are determined with better precision. The moduli of the individual form factors, determined for the first time, their ratio and the angular asymmetry of the annihilation reaction $e^{+} e^{-} \to p ˉ p$ are discussed. Fiits of the available data on the cross section, the effective form factor, and the form factor ratio, allow to propose a description of the electric and magnetic time-like form factors from the threshold up to the highest momenta.
Comments:
20 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2012.14656 [pdf]
PRC(2021)·35 citations
10
[Submitted on 30 Dec 2020] (cross-list from hep-ph)
Nonrelativistic Effective Field Theory with a Resonance Field
J. B. Habashi🇺🇸 · S. Fleming🇺🇸 · U. van Kolck🇫🇷
We discuss shallow resonances in the nonrelativistic scattering of two particles using an effective field theory (EFT) that includes an auxiliary field with the quantum numbers of the resonance. We construct the manifestly renormalized scattering amplitude up to next-to-leading order in a systematic expansion. For a narrow resonance, the amplitude is perturbative except in the immediate vicinity of the resonance poles. It naturally has a zero in the low-energy region, analogous to the Ramsauer-Townsend effect. For a broad resonance, the leading-order amplitude is nonperturbative almost everywhere in the regime of validity of the EFT. We regain the results of an EFT without the auxiliary field, which is equivalent to the effective-range expansion with large scattering length and effective range. We also consider an additional fine tuning leading to a low-energy amplitude zero even for a broad resonance. We show that in all cases the requirement of renormalizability when the auxiliary field is not a ghost ensures the resonance poles are in the lower half of the complex momentum plane, as expected by other arguments. The systematic character of the EFT expansion is exemplified with a toy model serving as underlying theory.
Comments:
19 pages, 14 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2012.14995 [pdf]
EPJA(2021)·21 citations
11
[Submitted on 30 Dec 2020] (cross-list from hep-ph)
Chiral separation effect catalyzed by heavy impurities
Daiki Suenaga🇯🇵 · Yasufumi Araki🇯🇵 · Kei Suzuki🇯🇵 · Shigehiro Yasui🇯🇵
We investigate the influence of Kondo effect, namely, the nonperturbative effect induced by heavy impurities, on the chiral separation effect (CSE) in quark matter. We employ a simple effective model incorporating the Kondo condensate made of a light quark and a heavy quark, and compute the response function of axial current to the magnetic field in static limit and dynamical limit. As a result, we find that the Kondo effect catalyzes the CSE in both the limits, and particularly the CSE in dynamical limit can be enhanced by a factor of approximately three. Our findings clearly show that the presence of heavy impurities in quark matter can play an important role in the transport phenomena of light quarks induced by a magnetic field.
Comments:
17 pages, 6 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Nuclear Theory (nucl-th)
arXiv:
2012.15173 [pdf]
PRD(2021)·9 citations
12
[Submitted on 30 Dec 2020] (cross-list from astro-ph.HE)
Neutron - mirror neutron mixing and neutron stars
Zurab Berezhiani🇮🇹 · Riccardo Biondi🇮🇹 · Massimo Mannarelli🇮🇹 · Francesco Tonelli🇮🇹
The oscillation of neutrons $n$ into mirror neutrons $n^{'}$ , their mass degenerate partners from dark mirror sector, can have interesting implications for neutron stars: an ordinary neutron star could gradually transform into a mixed star consisting in part of mirror dark matter. Mixed stars can be detectable as twin partners of ordinary neutron stars: namely, there can exist compact stars with the same masses but having different radii. For a given equation of state (identical between the ordinary and mirror components), the mass and radius of a mixed star depend on the proportion between the ordinary and mirror components in its interior which in turn depends on its age. If $50% - 50%$ proportion between two fractions can be reached asymptotically in time, then the maximum mass of such "maximally mixed stars" should be $2$ times smaller than that of ordinary neutron star while the stars exceeding a critical mass value $M_{N S}^{max} / 2$ should collapse in black holes after certain time. We evaluate the evolution time and discuss the implications of $n - n^{'}$ transition for the pulsar observations as well as for the gravitational waves from the neutron star mergers and associated electromagnetic signals.
Comments:
18 pages, 6 figures
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2012.15233 [pdf]
EPJC(2021)·63 citations
13
[Submitted on 30 Dec 2020] (cross-list from hep-th)
True Dynamical and Gauge Structures of the QCD Ground State and the Singular Gluon Fileds
Vakhtang Gogokhia🇭🇺 · Gergely Gábor Barnaföldi🇭🇺
We convincingly argue that the true dynamical and gauge structure of the QCD ground state is much more complicated than its Lagrangian exact gauge symmetry supposes to be. The dynamical source of these complications has been identified with the tadpole/seagull term, which renormalized version called, the mass gap. Its true dynamical role is hidden in the QCD ground state, but it is explicitly present in the full gluon self-energy. To disclose it the splintering between the transverse conditions for the full gluon self-energy and its subtracted counterpart has been derived. The equation of motion for the full gluon propagator on account of the mass gap was given, which allows to fix the dynamical and gauge structures by a newly-introduced generalized gauge. A novel non-perturbative analytical method, the mass gap approach was developed for QCD and its groud state as well. We have discovered a general, non-perturbative singular solution for the full gluon propagator valid in the whole gluon momentum range, while dominating at large distances over all the other possible solutions. It accommodates all the severe infrared singularities, which may appear in the QCD ground state due to the self-interaction of massless gluon modes. A corresponding non-pertubative multiplicative infrared renormalization program has been formulated. The resulting full gluon propagator prevents gluons to appear at large distances as physical states (confinement of color gluons). Our approach also explains the scale violation in the asymptotic freedom regime, and why the rising potential between heavy quarks is only linear one.
Comments:
38 pages, 3 figures
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2012.15337 [pdf]
1 citation
14
[Submitted on 31 Dec 2020] (cross-list from hep-th)
Convergence of hydrodynamic modes: insights from kinetic theory and holography
Michal P. Heller🇩🇪 · Alexandre Serantes🇵🇱 · Michał Spaliński🇵🇱 · Viktor Svensson🇵🇱 · Benjamin Withers🇬🇧
We study the mechanisms setting the radius of convergence of hydrodynamic dispersion relations in kinetic theory in the relaxation time approximation. This introduces a qualitatively new feature with respect to holography: a nonhydrodynamic sector represented by a branch cut in the retarded Green's function. In contrast with existing holographic examples, we find that the radius of convergence in the shear channel is set by a collision of the hydrodynamic pole with a branch point. In the sound channel it is set by a pole-pole collision on a non-principal sheet of the Green's function. More generally, we examine the consequences of the Implicit Function Theorem in hydrodynamics and give a prescription to determine a set of points that necessarily includes all complex singularities of the dispersion relation. This may be used as a practical tool to assist in determining the radius of convergence of hydrodynamic dispersion relations.
Comments:
v1: 25 pages, 13 figures; v2: typos corrected, version published in SciPost
Subjects:
High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th); Fluid Dynamics (physics.flu-dyn)
arXiv:
2012.15393 [pdf]
SciPost Phys.(2021)·51 citations
15
[Submitted on 31 Dec 2020] (cross-list from astro-ph.HE)
Studying the onset of deconfinement with multi-messenger astronomy of neutron stars
David Blaschke🇵🇱 · Mateusz Cierniak🇵🇱
With the first multi-messenger observation of a binary neutron star merger (GW170817) new constraints became available for masses and radii of neutron stars. We introduce a class of hybrid EoS that fulfils all these constraints and predicts a region in the mass-radius diagram that could be populated only by hybrid neutron stars with quark matter cores. A confirmation of this conjecture would be provided when the NICER radius measurement for the high-mass pulsar PSR J0740+6620 yields a radius less than 11 km. Would this radius measurement yield a result in excess of 12 km, this would allow for both, a purely hadronic and a hybrid nature of this star. In the latter case the maximum mass could reach $2.6 M_{⊙}$ so that the lighter object in the asymmetric binary merger GW190814 could have been a hybrid star. We demonstrate that this high mass can be compatible with an early onset of deconfinement at star masses below $1 M_{⊙}$ and the occurrence of low-mass twin stars. In such a case the remnant of GW170817 could be a long-lived hypermassive pulsar.
Comments:
7 pages, 5 figures, 1 table, revised and extended text, added formula, acknowledgement and references, version accepted for publication in Astron. Nachr
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2012.15785 [pdf]
Astron.Nachr.(2021)·34 citations
16
[Submitted on 31 Dec 2020] (cross-list from hep-th)
Constraints on quasinormal modes and bounds for critical points from pole-skipping
Navid Abbasi🇨🇳 · Matthias Kaminski🇺🇸
We consider a holographic thermal state and perturb it by a scalar operator whose associated real-time Green's function has only gapped poles. These gapped poles correspond to the non-hydrodynamic quasinormal modes of a massive scalar perturbation around a Schwarzschild black brane. Relations between pole-skipping points, critical points and quasinormal modes in general emerge when the mass of the scalar and hence the dual operator dimension is varied. First, this novel analysis reveals a relation between the location of a mode in the infinite tower of quasinormal modes and the number of pole-skipping points constraining its dispersion relation at imaginary momenta. Second, for the first time, we consider the radii of convergence of the derivative expansions about the gapped quasinormal modes. These convergence radii turn out to be bounded from above by the set of all pole-skipping points. Furthermore, a transition between two distinct classes of critical points occurs at a particular value for the conformal dimension, implying close relations between critical points and pole-skipping points in one of those two classes. We show numerically that all of our results are also true for gapped modes of vector and tensor operators.
Comments:
27 pages, 11 figures, comments welcome. v2: references added, minor corrections, journal version
Subjects:
High Energy Physics — Theory (hep-th); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2012.15820 [pdf]
JHEP(2021)·44 citations

Affiliations

first authorsco-authorsvia INSPIRE