Nuclear Theory·nucl-th

Friday·November 11, 2022

7 papers—2 primary·5 cross-listed

03
Reverse phase transitions in binary neutron-star systems with exotic-matter cores
Maximiliano Ujevic🇧🇷 · Henrique Gieg🇧🇷 · Federico Schianchi🇩🇪 · Swami Vivekanandji Chaurasia🇸🇪 · Ingo Tews🇺🇸 · Tim Dietrich🇩🇪
Multi-messenger observations of binary neutron star mergers provide a unique opportunity to constrain the dense-matter equation of state. Although it is known from quantum chromodynamics that hadronic matter will undergo a phase transition to exotic forms of matter, e.g., quark matter, the onset density of such a phase transition cannot be computed from first principles. Hence, it remains an open question if such phase transitions occur inside isolated neutron stars or during binary neutron star mergers, or if they appear at even higher densities that are not realized in the Cosmos. In this article, we perform numerical-relativity simulations of neutron-star mergers and investigate scenarios in which the onset density of such a phase transition is exceeded in at least one inspiralling binary component. Our simulations reveal that shortly before the merger it is possible that such stars undergo a "reverse phase transition", i.e., densities decrease and the quark core inside the star disappears leaving a purely hadronic star at merger. After the merger, when densities increase once more, the phase transition occurs again and leads, in the cases considered in this work, to a rapid formation of a black hole. We compute the gravitational-wave signal and the mass ejection for our simulations of such scenarios and find clear signatures that are related to the post-merger phase transition, e.g., smaller ejecta masses due to the softening of the equation of state through the quark core formation. Unfortunately, we do not find measurable imprints of the reverse phase transition.
↳ gr-qcastro-ph.HEnucl-thPRD(2023)·22 citations
04
Mueller's dipole wave function in QCD: emergent KNO scaling in the double logarithm limit
Yizhuang Liu🇵🇱 · Maciej A. Nowak🇵🇱 · Ismail Zahed🇺🇸
We analyze Mueller's QCD dipole wave function evolution in the double logarithm approximation (DLA). Using complex analytical methods, we show that the distribution of dipole in the wave function (gluon multiplicity distribution) asymptotically satisfies the Koba-Nielsen-Olesen (KNO) scaling, with a non-trivial scaling function $f (z)$ with $z = \frac{n}{n ˉ}$ . The scaling function decays exponentially as $2 (2.55)^{2} z e^{- \frac{z}{0.3917}}$ at large $z$ , while its growth is log-normal as $e^{- \frac{1}{2} l n^{2} z}$ for small- $z$ . A detailed analysis of the Fourier-Laplace transform of $f (z)$ , allows for performing the inverse Fourier transform, and access the non-asymptotic bulk-region around the peak. The bulk and asymptotic results are shown to be in good agreement with the measured hadronic multiplicities in DIS, as reported by the H1 collaboration at HERA in the region of large $Q^{2}$ . A numerical tabulation of $f (z)$ is included. Remarkably, the same scaling function is found to emerge in the resummation of double logarithms in the evolution of jets. Using the generating function approach, we show why this is the case. The absence of KNO scaling in non-critical and super-renormalizable theories is briefly discussed. We also discuss the universal character of the entanglement entropy in the KNO scaling limit, and its measurement using the emitted multiplicities in DIS and $e^{+} e^{-}$ annihilation.
↳ hep-phhep-thnucl-exnucl-thPRD(2023)·24 citations
05
The proton radius and its relatives -- much ado about nothing?
Ulf-G. Meißner🇩🇪
I summarize the dispersion-theoretical analysis of the nucleon electromagnetic form factors. Special emphasis is given on the extraction of the proton charge radius and its relatives, the proton magnetic radius as well as the neutron magnetic radius. Some recent work on the hyperfine splitting in leptonic hydrogen and on radiative corrections to muon-proton scattering is also discussed. Some views on future studies are given.
↳ hep-phhep-exhep-latnucl-ex+1J.Phys.Conf.Ser.(2023)·9 citations
06
Hydrodynamization in hybrid Bjorken flow attractors
Toshali Mitra🇮🇳 · Sukrut Mondkar🇮🇳 · Ayan Mukhopadhyay🇮🇳 · Anton Rebhan🇦🇹 · Alexander Soloviev🇦🇹
Hybrid fluid models, consisting of two sectors with more weakly and more strongly self-interacting degrees of freedom coupled consistently as in the semi-holographic framework, have been shown to exhibit an attractor surface for Bjorken flow. Retaining only the simple viscid fluid descriptions of both sectors, we find that, on the attractor surface, the hydrodynamization times of both subsectors decrease with increasing total energy density at the respective point of hydrodynamization following a conformal scaling, reach their minimum values, and subsequently rise rapidly. The minimum values are obtained when the respective energy densities are of the order of the inverse of the dimensionful inter-system coupling. Restricting to attractor curves which can be matched to glasma models at a time set by the saturation scale for both $p$ - $p$ and Pb-Pb collisions, we find that the more weakly coupled sector hydrodynamizes much later, and the strongly coupled sector hydrodynamizes earlier in $p$ - $p$ collisions, since the total energy densities at the respective hydrodynamization times of these sectors fall inside and outside of the conformal window. This holds true also for phenomenologically relevant solutions that are significantly away from the attractor surface at the time we match to glasma models.
↳ hep-phhep-thnucl-thJHEP(2024)·8 citations
07
Phenomenological description of the $π^{-} π^{+}$ $S$ -waves in $D^{+} \to π^{-} π^{+} π^{+}$ and $D_{s}^{+} \to π^{-} π^{+} π^{+}$ decays: The problem of phases
N.N. Achasov🇷🇺 · G.N. Shestakov🇷🇺
We present a phenomenological description of the LHCb data for the magnitudes and phases of the $π^{-} π^{+}$ $S$ -wave amplitudes in the $D^{+} \to π^{-} π^{+} π^{+}$ and $D_{s}^{+} \to π^{-} π^{+} π^{+}$ decays. We operate within a simple model that takes into account the known pair interactions of particles in coupled channels. The seed complex amplitudes for various intermediate state production are assumed to be independent of the energy. Their values are determined by fitting. This model gives the satisfactorily description of virtually all features of the energy dependence of the experimentally measured $S$ -wave amplitudes in the $D^{+} \to π^{-} π^{+} π^{+}$ and $D_{s}^{+} \to π^{-} π^{+} π^{+}$ decays in the regions $2 m_{π} < m_{π^{-} π^{+}} < 1.39 \mbox G e V$ and $2 m_{π} < m_{π^{-} π^{+}} < 1.29 \mbox G e V$ , respectively.
↳ hep-phhep-exnucl-exnucl-thPRD(2023)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE

Reverse phase transitions in binary neutron-star systems with exotic-matter cores

Mueller's dipole wave function in QCD: emergent KNO scaling in the double logarithm limit

The proton radius and its relatives -- much ado about nothing?

Hydrodynamization in hybrid Bjorken flow attractors

Phenomenological description of the π−π+ S-waves in D+→π−π+π+ and Ds+​→π−π+π+ decays: The problem of phases

Affiliations

Phenomenological description of the $π^{-} π^{+}$ $S$ -waves in $D^{+} \to π^{-} π^{+} π^{+}$ and $D_{s}^{+} \to π^{-} π^{+} π^{+}$ decays: The problem of phases