Nuclear Theory·nucl-th

Wednesday·October 7, 2020

14 papers—6 primary·8 cross-listed

07
[Submitted on 25 Sept 2020] (cross-list from astro-ph.HE)
The special point on the hybrid star mass--radius diagram and its multi--messenger implications
Mateusz Cierniak🇵🇱 · David Blaschke🇵🇱
We show the existence and investigate the location of the special point (SP) in which hybrid neutron star mass-radius (M-R) curves have to cross each other when they belong to a class of hybrid equation of state (EoS) constructed with generic constant--speed--of--sound (CSS) quark matter models for which the onset deconfinement is varied. We demonstrate that for a three-parameter CSS model the position of the SP in the M-R diagram is largely independent of the choice of the hadronic EoS, but in dependence on the stiffness of the quark matter EoS it spans a region that we identify. We find that the difference between the maximum mass and the SP mass depends on the mass at the onset of deconfinement so that an upper limit of $0.19 M_{⊙}$ for this difference is obtained from which a lower limit on the radius of hybrid stars is deduced. Together with a lower limit on the radius of hadronic stars, derived from a class of reasonably soft hadronic EoS including hyperons, we identify a region in the M-R diagram which can be occupied only by hybrid stars. Accordingly, we suggest that a NICER radius measurement on the massive pulsar PSR J0740+6620 in the range of 8.6-11.9 km would indicate that this pulsar is a hybrid neutron star with deconfined quark matter in the inner core.
Comments:
9 pages, 4 figures; figures 2 and 4 have been modified and discussion of hypernuclear matter is added
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2009.12353 [pdf]
Eur.Phys.J.ST(2020)·30 citations
08
[Submitted on 5 Oct 2020] (cross-list from hep-ph)
$∣Δ B ∣ = 2$ : A State of the Field, and Looking Forward--A brief status report of theoretical and experimental physics opportunities
Kaladi Babu · Joshua Barrow · Zurab Berezhiani · Leah Broussard · Marcel Demarteau · Bhupal Dev · Jordy de Vries · Alexey Fomin · Susan Gardner · Sudhakantha Girmohanta · Julian Heeck · Yuri Kamyshkov and 12 other authors
The origin of the matter-antimatter asymmetry apparently obligates the laws of physics to include some mechanism of baryon number ( $B$ ) violation. Searches for interactions violating $B$ and baryon-minus-lepton number $(B - L)$ represent a rich and underutilized opportunity. These are complementary to the existing, broad program of searches for $L$ -violating modes such as neutrinoless double $β$ -decay which could provide deeper understandings of the plausibility of leptogenesis, or $B$ -violating, $(B - L)$ -conserving processes such as proton decay. In particular, a low-scale, post-sphaleron violation mechanism of $(B - L)$ could provide a \textit{testable} form of baryogenesis. Though theoretically compelling, searches for such $(B - L)$ -violating processes like $Δ B = 2$ dinucleon decay and $n \to n ˉ$ remain relatively underexplored experimentally compared to other rare processes. By taking advantage of upcoming facilities such as the Deep Underground Neutrino Experiment and the European Spallation Source, this gap can be addressed with new intranuclear and free searches for neutron transformations with very high sensitivity, perhaps greater than three orders of magnitude higher than previous experimental searches. This proceedings reports on recent theoretical and experimental advances and sensitivities of next-generation searches for neutron transformations were detailed as part of the Amherst Center for Fundamental Interactions Workshop, "Theoretical Innovations for Future Experiments Regarding Baryon Number Violation," directly coordinated with the Rare Processes and Precision Measurements Frontier.
Comments:
Amherst Center for Fundamental Interactions workshop proceedings with short and long abstracts
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2010.02299 [pdf]
21 citations
09
[Submitted on 5 Oct 2020] (cross-list from hep-ph)
Axion-Polaritons in the Magnetic Dual Chiral Density Wave Phase of Dense QCD
Efrain J. Ferrer🇺🇸 · Vivian de la Incera🇺🇸
We investigate the propagation of electromagnetic radiation in the magnetic dual chiral density wave (MDCDW) phase of dense quark matter. Considering the theory of low-energy fluctuations in this phase, we show how linearly polarized photons reaching the MDCDW medium couple to the fluctuation field to produce two hybridized modes of propagation that we call in analogy with similar phenomenon in condensed matter physics axion polaritons, one of them being gapless and the other gapped. The gapped mode's gap is proportional to the background magnetic field and inversely proportional to the amplitude of the inhomogeneous condensate. The generation of axion polaritons can be traced back to the presence of the chiral anomaly in the low-energy theory of the fluctuations. Considering the Primakoff effect in the MDCDW medium, we argued that axion polaritons can be generated inside quark stars bombarded by energetic photons coming from gamma-ray bursts and point out that this mechanism could serve to explain the missing pulsar paradox in the galaxy center.
Comments:
Some formulas were changed
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2010.02314 [pdf]
NPB(2023)·12 citations
10
[Submitted on 5 Oct 2020] (cross-list from hep-ex)
Measurement of Differential Cross Sections for $ν_{μ}$ -Ar Charged-Current Interactions with Protons and no Pions in the Final State with the MicroBooNE Detector
MicroBooNE collaboration: P. Abratenko🇺🇸 · M. Alrashed🇺🇸 · R. An🇺🇸 · J. Anthony🇬🇧 · J. Asaadi🇺🇸 · A. Ashkenazi🇺🇸 · S. Balasubramanian🇺🇸 · B. Baller🇺🇸 · C. Barnes🇺🇸 · G. Barr🇬🇧 · V. Basque🇬🇧 · L. Bathe-Peters🇺🇸 and 172 other authors
We present an analysis of MicroBooNE data with a signature of one muon, no pions, and at least one proton above a momentum threshold of 300 MeV/c (CC0 $π$ Np). This is the first differential cross section measurement of this topology in neutrino-argon interactions. We achieve a significantly lower proton momentum threshold than previous carbon and scintillator-based experiments. Using data collected from a total of approximately $1.6 \times 1 0^{20}$ protons-on-target, we measure the muon neutrino cross section for the CC0 $π$ Np interaction channel in argon at MicroBooNE in the Booster Neutrino Beam which has a mean energy of around 800 MeV. We present the results from a data sample with estimated efficiency of 29\% and purity of 76\% as differential cross sections in five reconstructed variables: the muon momentum and polar angle, the leading proton momentum and polar angle, and the muon-proton opening angle. We include smearing matrices that can be used to "forward-fold" theoretical predictions for comparison with these data. We compare the measured differential cross sections to a number of recent theory predictions demonstrating largely good agreement with this first-ever data set on argon.
Comments:
24 pages, 43 figures, 1 table and supplemental material
Subjects:
High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th); Instrumentation and Detectors (physics.ins-det)
arXiv:
2010.02390 [pdf]
PRD(2020)·90 citations
11
[Submitted on 5 Oct 2020] (cross-list from nucl-ex)
Negative heat capacity for hot nuclei using formulation from the microcanonical ensemble INDRA Collaboration
B. Borderie · S. Piantelli · E. Bonnet · R. Bougault · A. Chbihi · J.E. Ducret · J.D. Frankland · E. Galichet · D. Gruyer · M. Henri · M. La Commara · N. Le Neindre and 6 other authors
By using freeze-out properties of multifragmenting hot nuclei produced in quasifusion central $^{129}$ Xe+ $^{na t}$ Sn collisions at different beam energies (32, 39, 45 and 50 AMeV) which were estimated by means of a simulation based on experimental data collected by the $4 π$ INDRA multidetector, heat capacity in the thermal excitation energy range 4 - 12.5 AMeV was calculated from total kinetic energies and multiplicities at freeze-out. The microcanonical formulation was employed. Negative heat capacity which signs a first order phase transition for finite systems is observed and confirms previous results using a different method.
Comments:
6 pages,5 figures. arXiv admin note: text overlap with arXiv:1903.02881
Subjects:
Nuclear Experiment (nucl-ex); Statistical Mechanics (cond-mat.stat-mech); Nuclear Theory (nucl-th)
arXiv:
2010.02736 [pdf]
EPJA(2020)·3 citations
12
[Submitted on 6 Oct 2020] (cross-list from hep-ph)
Jet evolution in a dense QCD medium
Paul Caucal🇫🇷
To probe the properties of the quark-gluon plasma created in heavy-ion collisions, a very useful class of observables refers to the propagation of energetic jets. A jet is a collimated spray of particles generated via successive parton branchings, starting with a virtual quark or gluon produced by the collision. When such a jet is produced in the dense environment of a nucleus-nucleus collision, its interactions with the surrounding medium lead to a modification of its properties, phenomenon known as jet quenching. In this thesis, we develop a new theory to describe jet quenching. We compute for the first time the effects of the medium on multiple vacuum-like emissions, that is emissions triggered by the virtuality of the initial parton. We present a new physical picture for jet evolution, with notably a factorisation in time between vacuum-like emissions and medium-induced emissions. This picture is Markovian, hence well suited for a Monte Carlo implementation that we develop in the parton shower JetMed. We then investigate the phenomenological consequences of our new picture on jet observables and especially the jet nuclear modification factor $R_{AA}$ , the Soft Drop $z_{g}$ distribution and the jet fragmentation function. Our Monte Carlo results prove to be in good agreement with the LHC measurements.
Comments:
Ph.D. dissertation; 278 pages
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2010.02874 [pdf]
15 citations
13
[Submitted on 6 Oct 2020] (cross-list from hep-ph)
Viscous properties of hot and dense QCD matter in the presence of a magnetic field
Shubhalaxmi Rath🇮🇳 · Binoy Krishna Patra🇮🇳
We have studied the effect of strong magnetic field on the viscous properties of hot QCD matter at finite chemical potential by calculating the shear ( $η$ ) and bulk ( $ζ$ ) viscosities. The viscosities are calculated using kinetic theory in the relaxation time approximation. The interactions are incorporated through the quasiparticle masses of partons at strong magnetic field and finite chemical potential. From this study, one can understand the effects of strong magnetic field and chemical potential on the sound attenuation through the Prandtl number (Pl), on the nature of the flow by the Reynolds number (Rl), and on the relative behavior between shear viscosity and bulk viscosity through the ratio $ζ / η$ . We have found that, $η$ and $ζ$ get increased in a strong magnetic field and the additional presence of chemical potential further enhances their magnitudes. With the increase of temperature, $η$ increases in a strong magnetic field as well as in the absence of magnetic field, whereas $ζ$ decreases with the temperature, contrary to its increase in the absence of magnetic field. We have observed that, the Prandtl number gets increased in the presence of strong magnetic field and chemical potential as compared to the isotropic one, but it always remains larger than 1, thus the momentum diffusion largely affects the sound attenuation in the medium. The Reynolds number gets lowered than 1 in a strong magnetic field and it becomes further decreased in an additional presence of chemical potential, so the kinematic viscosity dominates over the characteristic length scale of the system. Finally, $ζ / η$ becomes larger than 1, contrary to its value in the absence of magnetic field and chemical potential where it is less than 1, so the bulk viscosity prevails over the shear viscosity for the hot and dense QCD matter in the presence of a strong magnetic field.
Comments:
39 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2010.02886 [pdf]
EPJC(2021)·19 citations
14
[Submitted on 6 Oct 2020] (cross-list from astro-ph.HE)
Rapidly rotating $Δ$ -resonance-admixed hypernuclear compact stars
Jia Jie Li🇨🇳 · Armen Sedrakian🇩🇪 · Fridolin Weber🇺🇸
We use a set of hadronic equations of state derived from covariant density functional theory to study the impact of their high-density behavior on the properties of rapidly rotating $Δ$ -resonance-admixed hyperonic compact stars. In particular, we explore systematically the effects of variations of the bulk energy isoscalar skewness, $Q_{sat}$ , and the symmetry energy slope, $L_{sym}$ , on the masses of rapidly rotating compact stars. With models for equation of state satisfying all the modern astrophysical constraints, excessively large gravitational masses of around $2.5 M_{⊙}$ are only obtained under three conditions: (a) strongly attractive $Δ$ -resonance potential in nuclear matter, (b) maximally fast (Keplerian) rotation, and (c) parameter ranges $Q_{sat} ≳ 500$ MeV and $L_{sym} ≲ 50$ MeV. These values of $Q_{sat}$ and $L_{sym}$ have a rather small overlap with a large sample (total of about 260) parametrizations of covariant nucleonic density functionals. The extreme nature of requirements (a)-(c) reinforces the theoretical expectation that the secondary object involved in the GW190814 event is likely to be a low-mass black hole rather than a supramassive neutron star.
Comments:
8 pages with 5 figures, matches published version
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2010.02901 [pdf]
PLB(2020)·50 citations

Affiliations

first authorsco-authorsvia INSPIRE