Nuclear Theory·nucl-th

Thursday·December 22, 2022

11 papers—4 primary·7 cross-listed

05
Constraints on strong phase transitions in neutron stars
Tyler Gorda🇩🇪 · Kai Hebeler🇩🇪 · Aleksi Kurkela🇳🇴 · Achim Schwenk🇩🇪 · Aleksi Vuorinen🇫🇮
We study current bounds on strong first-order phase transitions (PTs) along the equation of state (EOS) of dense strongly interacting matter in neutron stars, under the simplifying assumption that on either side of the PT the EOS can be approximated by a simple polytropic form. We construct a large ensemble of possible EOSs of this form, anchor them to chiral effective field theory calculations at nuclear density and perturbative QCD at high densities, and subject them to astrophysical constraints from high-mass pulsars and gravitational-wave observations. Within this setup, we find that a PT permits neutron-star solutions with larger radii, but only if the transition begins below twice nuclear saturation density. We also identify a large parameter space of allowed PTs currently unexplored by numerical-relativity studies. Additionally, we locate a small region of parameter space allowing twin-star solutions, though we find them to only marginally pass the current astrophysical constraints. Finally, we find that sizeable cores of high-density matter beyond the PT may be located in the centers of some stable neutron stars, primarily those with larger masses.
↳ astro-ph.HEhep-phnucl-thApJ(2023)·54 citations
06
The time-like electromagnetic kaon form factor
A.S. Miramontes🇲🇽 · Adnan Bashir🇲🇽
We compute the electromagnetic charged kaon form factor in the time-like region by employing a Poincaré covariant formalism of the Bethe-Salpeter equation to study quark-antiquark bound states in conjunction with the Schwinger-Dyson equation for the quark propagator. Following a recent kindred calculation of the time-like electromagnetic pion form factor, we include the most relevant intermediate composite particles permitted by their quantum numbers in the interaction kernel to allow for a decay mechanism for the resonances involved. This term augments the usual gluon mediated interaction between quarks. For a sufficiently low energy time-like probing photon, the electromagnetic form factor is saturated by the $ρ (770)$ and $ϕ (1020)$ resonances. We assume $S U (2)$ isospin symmetry throughout. Our results for the absolute value squared of the electromagnetic form factor agree qualitatively rather well and quantitatively moderately so with available experimental data.
↳ hep-phnucl-thPRD(2023)·14 citations
07
Neutron Star versus Neutral Star: On the 90th anniversary of Landau's publication in astrophysics
Renxin Xu (PKU)
In the late age of developing quantum mechanics, Lev Landau, one of the distinguished players, made great efforts to understand the nature of matter, even stellar matter, by applying the quantum theory. Ninety years ago, he published his idea of "neutron" star, which burst upon him during his visit over Europe in the previous year. The key point that motivated Landau to write the paper is to make a state with lower energy for "gigantic nucleus", avoiding extremely high kinematic energy of electron gas due to the new Fermi-Dirac statistics focused hotly on at that time. Landau had no alternative but to neutronize/neutralize by "combining a proton and an electron", as electron and proton were supposed to be elementary before the discovery of neutron. However, our understanding of the Nature has fundamentally improved today, and another way (i.e., strangeonization) could also embody neutralization and thus a low-energy state that Landau had in mind, which could further make unprecedented opportunities in this multi-messenger era of astronomy. Strangeon matter in "old" physics may impact dramatically on today's physics, from compact stars initiated by Landau, to cosmic rays and dark matter. In this essay, we are making briefly the origin and development of neutron star concept to reform radically, to remember Landau's substantial contribution in astrophysics and to recall those peculiar memories.
↳ physics.hist-phastro-ph.HEhep-phnucl-thAstron.Nachr.(2023)·7 citations
08
Unobservability of topological charge in nonabelian gauge theory
Nodoka Yamanaka🇯🇵
We show that the topological charge of nonabelian gauge theory is unphysical by using the fact that it always involves the unphysical gauge field component proportional to the gradient of the gauge function. The removal of Gribov copies, which may break the Becchi-Rouet-Stora-Tyutin symmetry, is irrelevant thanks to the perturbative one-loop finiteness of the chiral anomaly. The unobservability of the topological charge immediately leads to the resolution of the Strong CP problem. We also present important consequences such as the physical relevance of axial $U (1)$ symmetry, the $θ$ -independence of vacuum energy, the unphysicalness of topological instantons, and the impossibilities of realizing the sphaleron induced baryogenesis as well as the chiral magnetic effect. The unphysical vacuum angle and the axial $U (1)$ symmetry also imply that the CP phase of the Cabibbo-Kobayashi-Maskawa matrix is the sole source of CP violation of the standard model.
↳ hep-thhep-lathep-phnucl-th17 citations
09
Neutrinoless Double Beta Decay
C. Adams🇺🇸 · K. Alfonso🇺🇸 · C. Andreoiu🇨🇦 · E. Angelico🇺🇸 · I.J. Arnquist🇺🇸 · J.A.A. Asaadi🇺🇸 · F.T. Avignone🇺🇸 · S. N. Axani🇺🇸 · A.S. Barabash🇷🇺 · P.S. Barbeau🇺🇸 · L. Baudis🇨🇭 · F. Bellini🇮🇹 and 220 other authors
This White Paper, prepared for the Fundamental Symmetries, Neutrons, and Neutrinos Town Meeting related to the 2023 Nuclear Physics Long Range Plan, makes the case for double beta decay as a critical component of the future nuclear physics program. The major experimental collaborations and many theorists have endorsed this white paper.
↳ nucl-exnucl-th48 citations
10
Odderon as Regge oddball spin-3 in $pp$ and $p p ˉ$ elastic scattering
Jingle B. Magallanes🇵🇭 · Prin Sawasdipol🇹🇭 · Chakrit Pongkitivanichkul🇹🇭 · Daris Samart🇹🇭
In this work, we propose that the odderon is a Regge odd-glueball tensor spin-3. To demonstrate our proposal, we study the $pp$ and $p p ˉ$ elastic scattering by including contributions of the spin-3 odderon and spin-2 pomeron exchange in the processes. The phenomenological effective Lagrangian approach is used to calculate the $pp$ and $p p ˉ$ elastic scattering amplitudes at the tree level. In addition, a Donnachie-Landschoff ansatz of the odderon and pomeron propagators has been used in this work. We fit the theoretical results with the various experimental data of the $pp$ and $p p ˉ$ scattering at the TeV scale to determine the model parameters in the present work. By using the model parameters, the Chew-Frautschi plot of the tensor odderon Regge trajectory is evaluated. As a result, the odderon spin-3 mass is predicted to be 3.2 GeV. In addition, the total cross-section of our model is compatible with the results from TOTEM and its extrapolation from D0 collaboration. Moreover, the total cross-section also satisfies the Friossart bound at the Regge limit.
↳ hep-phnucl-thPRD(2024)·4 citations
11
Non-strange quark stars within resummed QCD
Tulio E. Restrepo🇧🇷 · Constança Providência🇵🇹 · Marcus Benghi Pinto🇧🇷
The recently developed resummation technique known as {\it renormalization group optimized perturbation theory} (RGOPT) is employed in the evaluation of the EoS describing non-strange cold quark matter at NLO. Inspired by recent investigations, which suggest that stable quark matter can be made only of up and down quarks, the mass-radius relation for two flavor pure quark stars is evaluated and compared with the predictions from perturbative QCD (pQCD) at NNLO. This comparison explicitly shows that by being imbued with renormalization group properties, and a variational optimization procedure, the method allows for an efficient resummation of the perturbative series. Remarkably, when the renormalization scale is chosen so as to reproduce maximum mass stars with M= $2 - 2.3 M_{⊙}$ , one obtains a mass-radius curve compatible with the masses and radii of the pulsars PSR J0740+6620, PSR J0030+0451, and the compact object HESS J1731-347. Moreover, the scale dependence of the EoS (and mass-radius relation) obtained with the RGOPT is greatly improved when compared to that of pQCD. This seminal application to the description of quark stars shows that the RGOPT represents a robust alternative to pQCD when describing compressed quark matter.
↳ hep-phastro-ph.HEnucl-thPRD(2023)·24 citations

Affiliations

first authorsco-authorsvia INSPIRE

Constraints on strong phase transitions in neutron stars

The time-like electromagnetic kaon form factor

Neutron Star versus Neutral Star: On the 90th anniversary of Landau's publication in astrophysics

Unobservability of topological charge in nonabelian gauge theory

Neutrinoless Double Beta Decay

Odderon as Regge oddball spin-3 in pp and ppˉ​ elastic scattering

Non-strange quark stars within resummed QCD

Affiliations

Odderon as Regge oddball spin-3 in $pp$ and $p p ˉ$ elastic scattering