Nuclear Theory·nucl-th

Tuesday·December 19, 2023

25 papers—12 primary·13 cross-listed

01
Studying short-range nuclear correlations using relativistic heavy-ion collisions
Matthew Luzum🇧🇷 · João Paulo Picchetti🇧🇷 · Mauricio Hippert🇺🇸 · Jean-Yves Ollitrault🇫🇷
Recently, a method was developed for implementing arbitrary short-range nucleon-nucleon correlations in Monte Carlo sampled nuclei (as well as deformations of the 1-body nuclear density). We use this method to implement realistic 2-body correlations in a sample of nuclei for use in simulations of relativistic heavy-ion collisions and we quantify the statistical benefits. These results demonstrate that the method can be used to easily implement an arbitrary correlation function, and systematically study the effects of correlations using significantly less resources than is necessary with traditional methods.
nucl-thhep-phEPJ Web Conf.(2024)·1 citation
02
Which first order phase transitions to quark matter are possible in neutron stars?
Jan-Erik Christian🇩🇪 · Jürgen Schaffner-Bielich🇩🇪 · Stephan Rosswog🇩🇪
We examine which first order phase transitions are consistent with today's astrophysical constraints. In particular, we explore how a well-constrained mass-radius data point would restrict the admissible parameter space and to this end, we employ the most likely candidates of the recent NICER limits of PSR J0030+0451. To systematically vary the stiffness of the equation of state, we employ a parameterizable relativistic mean field equation of state, which is in compliance with results from chiral effective field theory. We model phase transitions via Maxwell constructions and parameterize them by means of the transitional pressure $p_{trans}$ and the jump in energy density $Δ ϵ$ . This provides us with a generic setup that allows for rather general conclusions to be drawn. We outline some regions in the $p_{trans}$ - $Δ ϵ$ parameter space that may allow for a phase transition identification in the near future. We also find that a strongly constrained data point, at either exceptionally large or small radii, would reduce the parameter space to such an extent that mass and radius become insufficient indicators of a phase transition.
nucl-thastro-ph.HEPRD(2024)·40 citations
03
Transverse momentum fluctuation in ultra-central Pb+Pb collision at the LHC
Rupam Samanta🇵🇱 · Somadutta Bhatta🇺🇸 · Jiangyon Jia🇺🇸 · Matthew Luzum🇧🇷 · Jean-Yves Ollitrault🇫🇷
The ATLAS collaboration has recently observed that the variance of the transverse momentum per particle ( $[p_{t}]$ ), when measured as a function of the collision multiplicity ( $N_{c h}$ ) in Pb+Pb collisions, decreases by a factor $2$ for the largest values of $N_{c h}$ , corresponding to ultra-central collisions. We show that this phenomenon is naturally explained by invoking impact parameter ( $b$ ) fluctuations, which contribute to the variance, and gradually disappear in ultra-central collisions. It implies that $N_{c h}$ and $[p_{t}]$ are strongly correlated at fixed $b$ , which is explained by the local thermalization of the QGP medium.
nucl-thnucl-exEPJ Web Conf.(2024)·0 citations
04
Thermal dilepton production in heavy-ion collisions at beam-energy-scan (BES) energies
Jessica Churchill🇨🇦 · Lipei Du🇨🇦 · Bailey Forster🇨🇦 · Han Gao🇨🇦 · Greg Jackson🇫🇷 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦
The lepton pair production rate at finite temperature and at next-to-leading-order (NLO) is calculated for quark-gluon plasma at non-zero baryon density. Yields are obtained using a (3+1)D multicomponent simulation capable of reproducing hadronic observables measured in the RHIC Beam Energy Scan. Spectra of intermediate invariant mass dileptons are compared with measurements from the STAR collaboration. The result of a study where the temperature information obtained from the dilepton spectrum from heavy-ion collisions performed at different energies and centralities is presented.
nucl-thhep-phEPJ Web Conf.(2024)·4 citations
05
Why are hydrodynamic theories applicable beyond the hydrodynamic regime?
Sunil Jaiswal🇺🇸 · Jean-Paul Blaizot🇫🇷 · Rajeev S. Bhalerao🇮🇳 · Zenan Chen🇨🇳 · Amaresh Jaiswal🇮🇳 · Li Yan🇨🇳
We present an alternative approach to deriving second-order non-conformal hydrodynamics from the relativistic Boltzmann equation. We demonstrate how constitutive relations for shear and bulk stresses can be transformed into dynamical evolution equations, resulting in Israel-Stewart-like (ISL) hydrodynamics. To understand the far-from-equilibrium applicability of such ISL theories, we investigate the one-dimensional boost-invariant Boltzmann equation using special moments of the distribution function for a system with finite particle mass. Our analysis reveals that the mathematical structure of the ISL equations is akin to that of moment equations, enabling them to approximately replicate even the collisionless dynamics. We conclude that this particular feature is important in extending the applicability of ISL theories beyond the hydrodynamic regime.
nucl-thhep-phEPJ Web Conf.(2024)·1 citation
06
Symmetry-restored Skyrme-Random-Phase-Approximation calculations of the monopole strength in deformed nuclei
A. Porro · G. Colò · T. Duguet · D. Gambacurta · V. Somà
Within the Energy Density Functional (EDF) approach, the use of mean-field wave-functions deliberately breaking (some) symmetries of the underlying Hamiltonian is an efficient and largely utilized way to incorporate static correlations. However, the restoration of broken symmetries is eventually mandatory to recover the corresponding quantum numbers and to achieve a more precise description of nuclear properties. While symmetry-restored calculations are routinely performed to study ground-state properties and low-lying excitations, similar applications to the nuclear response are essentially limited to either formal studies or to schematic models. In the present paper, the effect of angular momentum restoration on the monopole and quadrupole responses of doubly open-shell nuclei is investigated. Based on deformed Skyrme-Random Phase Approximation (RPA) calculations, the exact Angular Momentum Projection (AMP) is implemented in the calculation of the multipole strength functions, thus defining a projection after variation (PAV-RPA) scheme. The method is employed for the first time in a realistic study to investigate the effect of AMP on the coupling of monopole and quadrupole modes in $^{24}$ Mg resulting from its intrinsic deformation.
nucl-thnucl-exPRC(2024)·8 citations
07
Reply to the "Comment on `Effect of density and nucleon-nucleon potential on the fusion cross section within the relativistic mean field formalism'"
M. Bhuyan · Raj Kumar · Shilpa Rana · D. Jain · S. K. Patra · B. V. Carlson
In reply to the Comment made by M. V. Chushnyakova et al. on our paper [Phys. Rev. C 101, 044603 (2020)], we argue that the calculations, results and conclusions of our paper remain valid. We have shown here the calculations for one reaction using the deformed densities and the R3Y nucleon-nucleon potential obtained within the relativistic mean-field (RMF) formalism. Suitable clarications and justifications are given to address all the points raised in the Comment.
nucl-th0 citations
08
Benchmark of many-body approaches for magnetic dipole transition strength
M. Frosini🇫🇷 · W. Ryssens🇧🇪 · K. Sieja🇫🇷
The low-energy enhancement observed recently in the deexcitation gamma-ray strength functions, suggested to arise due to the magnetic dipole radiation, motivates theoretical efforts to improve the description of M1 strength in available nuclear structure models. Reliable theoretical predictions of nuclear dipole excitations are of interest for different nuclear applications and in particular for nuclear astrophysics, where the calculations of radiative capture cross sections often resort to theoretical strength functions. We aim to benchmark many-body methods in their description of the M1 strength functions, with a special emphasis on the low-energy effects observed in the deexcitation strength. We investigate the zero-temperature and finite-temperature magnetic dipole strength functions computed within the quasiparticle random-phase approximation and compare them to those from exact diagonalizations of the same Hamiltonian in restricted orbital spaces. The study is carried out for a sample of 25 spherical and deformed nuclei which can be described by diagonalization of the respective effective Hamiltonian in three different valence spaces. A reasonable agreement is found for the total photoabsorption strengths while the QRPA distributions are shown to be systematically shifted down in energy with respect to exact results. Photoemission strengths obtained within the FT-QRPA appear insufficient to explain the low-energy enhancement of the M1 strength functions. The problems encountered in QRPA calculations are ascribed to the lack of correlations in the nuclear ground state and to the truncation of the many-body space. In particular, the latter prevents obtaining the sufficiently high level density to produce the low-energy enhancement of the strength function, making the (FT-)QRPA approach unsuitable for predictions of such effects across the nuclear chart.
nucl-thPRC(2024)·7 citations
09
Simulating collectivity in dense baryon matter with multiple fluids
Jakub Cimerman🇨🇿 · Iurii Karpenko🇨🇿 · Boris Tomasik🇨🇿 · Pasi Huovinen🇵🇱
A novel three-fluid dynamical model for simulations of heavy-ion collisions at RHIC Beam Energy Scan programme, called MUFFIN, has been developed. The novelty consists of modular inclusion of the Equation of State, use of hyperbolic coordinates that allow to simulate higher collision energies, and fluctuating initial conditions. The model reproduces rapidity and $p_{t}$ spectra of collisions from $s_{N N}$ =7.7 to 62.4 GeV. Ideal fluid is assumed, and the elliptic flow is over-predicted, particularly at lower collision energies.
nucl-thEPJ Web Conf.(2024)·0 citations
10
Lattice-based equation of state with 3D Ising critical point
Micheal Kahangirwe · Steffen A. Bass · Johannes Jahan · Pierre Moreau · Paolo Parotto · Claudia Ratti · Olga Soloveva · Misha Stephanov · Elena Bratkovskaya
The BEST Collaboration equation of state combining lattice data with the 3D Ising critical point encounters limitations due to the truncated Taylor expansion up to $\frac{μ _{B}}{T} \sim 2.5$ . This truncation consequently restricts its applicability at high densities. Through a resummation scheme, the lattice results have been extended to $\frac{μ _{B}}{T} = 3.5$ . In this article, we amalgamate these ideas with the 3D-Ising model, yielding a family of equations of state valid up to $μ_{B} = 700 MeV$ with the correct critical behavior. Our equations of state feature tunable parameters, providing a stable and causal framework-a crucial tool for hydrodynamics simulations.
nucl-thEPJ Web Conf.(2024)·3 citations
11
Directed flow and hyperon polarization at RHIC BES from multi-fluid dynamics
Iurii Karpenko🇨🇿 · Jakub Cimerman🇨🇿
We present directed flow of protons and pions, as well as mean polarization of $Λ$ and $Λ ˉ$ hyperons computed for Au-Au collisions at $s_{NN} = 5...19.6$ GeV in MUFFIN model. MUlti Fluid simulation for Fast IoN collisions, or MUFFIN, is a state-of-the-art 3-fluid dynamic model for simulating heavy-ion collisions in the region from a few to a hundred GeV center-of-mass energy. Whereas MUFFIN succeeds to reproduce basic observables in the collision energy range of interest, the slope of the directed flow at mid-rapidity is much steeper as compared to the data, it has unclear EoS dependence and final-state hadronic cascade affects this observable significantly. The excitation function of the $Λ$ polarization shows a significant splitting between polarizations of $Λ$ and $Λ ˉ$ , which challenges a widespread interpretation that the splitting is affected mainly by the late-stage magnetic field.
nucl-thnucl-exEPJ Web Conf.(2024)·3 citations
12
Holographic transport coefficients and jet energy loss for the hot and dense quark-gluon plasma
Joaquin Grefa🇺🇸 · Mauricio Hippert🇺🇸 · Raghav Kunnawalkam Elayavalli🇺🇸 · Jacquelyn Noronha-Hostler🇺🇸 · Israel Portillo🇺🇸 · Claudia Ratti🇺🇸 · Romulo Rougemont🇧🇷
We employ an Einstein-Maxwell-dilaton model, based on the gauge/gravity correspondence, to obtain the thermodynamics and transport properties for the hot and dense quark-gluon plasma. The model, which is constrained to reproduce lattice QCD thermodynamics at zero density, predicts a critical point and a first order line at finite temperature and density, is used to quantify jet energy loss through simulations of high-energy collision events.
nucl-thhep-phhep-thnucl-exEPJ Web Conf.(2024)·3 citations
13
Gravitational form factors of the nucleon and one pion graviproduction in chiral EFT
H. Alharazin🇩🇪
In the framework of chiral effective field theory of delta resonances, nucleons and pions interacting with background gravitational field we calculate the gravitational form factors of the nucleon up to fourth order in the small scale expansion and obtain the long-range behavior of the corresponding contributions to the energy, spin, pressure and shear force distributions. By comparing nucleon gravitational form factors with and without delta contributions we conclude that explicit inclusion of deltas plays an important role. Next we explore the Lorentz structure of the $N \mapsto N π$ transition matrix element of the conserved symmetric energy-momentum tensor and introduce its parametrization in terms of twelve transition form factors. We use the chiral effective field theory to calculate the tree-order contributions to the gravitational transition form factors of the pion graviproduction off the nucleon up to third order.
↳ hep-phhep-thnucl-thPRD(2024)·15 citations
14
Pre-equilibrium photon production in QCD Kinetic Theory
Oscar Garcia-Montero🇩🇪 · Aleksas Mazeliauskas🇩🇪 · Philip Plaschke🇩🇪 · Sören Schlichting🇩🇪
We use QCD kinetic theory to compute photon production in the chemically equilibrating Quark-Gluon Plasma created in the early stages of high-energy heavy-ion collisions. We show that the photon spectrum radiated from an attractor evolution satisfies a simple scaling form in terms of the specific shear viscosity $η / s$ and entropy density $d S / d ζ \sim (T τ^{1/3})^{3/2}_{\infty}$ . We confirm the analytical predictions with numerical kinetic theory simulations. We use the extracted scaling function to compute the pre-equilibrium photon contribution in $s_{N N} = 2.76 TeV$ 0-20% PbPb collisions. We demonstrate that our matching procedure allows for a smooth switching from pre-equilibrium kinetic to thermal hydrodynamic photon production.
↳ hep-phnucl-thPoS(2024)·1 citation
15
Lattice QCD studies of the $Δ$ baryon resonance and the $K_{0}^{*} (700)$ and $a_{0} (980)$ meson resonances: the role of exotic operators in determining the finite-volume spectrum
John Bulava🇺🇸 · Danny Darvish🇩🇪 · Andrew D. Hanlon🇺🇸 · Ben Hörz🇺🇸 · Colin Morningstar🇩🇪 · Amy Nicholson🇺🇸 · Fernando Romero-López🇺🇸 · Sarah Skinner🇺🇸 · Pavlos Vranas🇺🇸 · André Walker-Loud🇺🇸
Studies of the $Δ$ baryon resonance and the $K_{0}^{*} (700)$ and $a_{0} (980)$ meson resonances using $N_{f} = 2 + 1$ lattice QCD for pion masses near 200 MeV are presented. The $s$ -wave scattering lengths for both the $I = 1/2$ $N π$ and $I = 3/2$ $N π$ channels and properties of the $Δ$ resonance are identified from the finite-volume energy levels of the lattice simulation. The importance of a three-quark $Δ$ -operator in the $N π$ system and tetraquark operators in the mesonic systems is investigated.
↳ hep-latnucl-thPoS(2024)·4 citations
16
The 95 GeV Excess in the Georgi-Machacek Model: Single or Twin Peak Resonance
Amine Ahriche (Sharjah U., UAE)🇦🇪
In this work, we investigate the possibility to address the excess observed around 95 GeV in the $γ γ$ , $τ τ$ , and $b b ˉ$ channels as a scalar resonance(s) within the Georgi-Machacek (GM) model. In our analysis, we find that the excess can be easily accommodated in the channels ( $γ γ$ and $b b ˉ$ ) simultaneously, where the 95 GeV candidate is a single peak resonance (SPR) due to a light CP-even scalar. We found that the excess in the $τ τ$ channel can be addressed simultaneously with $γ γ$ and $b b ˉ$ only if the 95 GeV candidate is a twin peak resonance (TPR), i.e., another CP-odd scalar in addition to the CP-even scalar. We demonstrate that the nature of the 95 GeV scalar resonance candidate (SPR or TPR) can be probed via the properties of its di- $τ$ decay.
↳ hep-phhep-exnucl-thPRD(2024)·38 citations
17
About the magnitude of the $γ^{*} N \to N (1520)$ transverse amplitudes near $Q^{2} = 0$
G. Ramalho🇰🇷
The $γ^{*} N \to N (1520)$ transition has a property that differs from the other low-lying nucleon resonance amplitudes: the magnitude of the transverse helicity amplitudes.The transition helicity amplitudes are defined in terms of square-transfer momentum $q^{2}$ , or $Q^{2} = - q^{2}$ . Near the photon point ( $Q^{2} = 0$ ) there is a significant difference in the magnitude of the transverse amplitudes: $A_{3/2}$ is very large and $A_{1/2}$ is very small. This atypical behavior contrasts with the relation between the amplitudes at the pseudothreshold [the limit where the nucleon and the $N (1520)$ are both at rest and $Q^{2} < 0$ ], where $A_{3/2} = A_{1/2} / 3$ , and also in the large- $Q^{2}$ region, where theory and data suggest that $A_{3/2}$ is suppressed relative to $A_{1/2}$ . In the present work, we look for the source of the suppression of the $A_{1/2}$ amplitude at $Q^{2} = 0$ . The result is easy to understand in first approximation, when we look into the relation between the transverse amplitudes and the elementary form factors, defined by a gauge-invariant parametrization of the $γ^{*} N \to N (1520)$ transition current, near $Q^{2} = 0$ . There is a partial cancellation between contributions of two elementary form factors near $Q^{2} = 0$ . We conclude, however, that the correlation between the two elementary form factors at $Q^{2} = 0$ is not sufficient to explain the transverse amplitude data below $Q^{2} = 1$ GeV $^{2}$ . The description of the dependence of the transverse amplitudes on $Q^{2}$ requires the determination of the scale of variation of the elementary form factors in the range $Q^{2} = 0$ ...0.5 GeV $^{2}$ ,a region with almost non existent data. We conclude at the end that the low- $Q^{2}$ data for the transverse amplitudes can be well described when we relate the scale of variation of the elementary form factors with the nucleon dipole form factor.
↳ hep-phhep-exhep-latnucl-ex+1PRD(2024)·1 citation
18
Superconducting phases of strongly-interacting matter in large magnetic fields
Geraint W. Evans🇬🇧
The large magnetic fields of neutron stars and produced in heavy-ion collisions motivate investigation into the response of strongly-interacting matter to extreme magnetic forces beyond just theoretical interest. Furthermore, the varying temperature $T$ , baryon chemical potential $μ_{B}$ , and aforementioned magnetic fields $B$ , of these systems leads to questions concerning the phase structure of Quantum Chromodynamics (QCD) at large. At low temperatures, superconducting phases become a possible candidate for the ground state in the $μ_{B}$ - $B$ plane. This thesis investigates two scenarios where these phases emerge at $T = 0$ , with an emphasis on the type-II regime. Preceding the presentation of these works, the $μ_{B}$ - $B$ plane of the QCD phase diagram is reviewed such that the results can be placed in the wider context of this plane.
↳ hep-phhep-thnucl-th0 citations
19
Systematic Improvement of $x$ -dependent Unpolarized Nucleon Generalized Parton Distribution in Lattice-QCD Calculation
Jack Holligan🇺🇸 · Huey-Wen Lin🇺🇸
We present a first study of the effects of renormalization-group resummation (RGR) and leading-renormalon resummation (LRR) on the systematic errors of the unpolarized isovector nucleon generalized parton distribution in the framework of large-momentum effective theory (LaMET). This work is done using lattice gauge ensembles generated by the MILC collaboration, consisting of 2+1+1 flavors of highly improved staggered quarks with a physical pion mass at lattice spacing $a \approx 0.09$ fm and a box width $L \approx 5.76$ fm. We present results for the nucleon $H$ and $E$ GPDs with average boost momentum $P_{z} \approx 2$ GeV at momentum transfers $Q^{2} = [0, 0.97]$ GeV $^{2}$ at skewness $ξ = 0$ as well as $Q^{2} \in 0.23$ GeV $^{2}$ at $ξ = 0.1$ , renormalized in the $MS$ scheme at scale $μ = 2.0$ GeV, with two- and one-loop matching, respectively. We demonstrate that the simultaneous application of RGR and LRR significantly reduces the systematic errors in renormalized matrix elements and distributions for both the zero and nonzero skewness GPDs, and that it is necessary to include both RGR and LRR at higher orders in the matching and renormalization processes.
↳ hep-lathep-phnucl-thPRD(2024)·29 citations
20
Non-Abelian chiral soliton lattice in rotating QCD matter: Nambu-Goldstone and excited modes
Minoru Eto🇯🇵 · Kentaro Nishimura🇯🇵 · Muneto Nitta🇯🇵
The ground state of QCD with two flavors at a finite baryon chemical potential under rapid rotation is a chiral soliton lattice (CSL) of the $η$ meson, consisting of a stack of sine-Gordon solitons carrying a baryon number, due to the anomalous coupling of the $η$ meson to the rotation. In a large parameter region, the ground state becomes a non-Abelian CSL, in which due to the neutral pion condensation each $η$ soliton decays into a pair of non-Abelian sine-Gordon solitons carrying $S^{2}$ moduli originated from Nambu-Goldstone (NG) modes localized around it, corresponding to the spontaneously broken vector symmetry SU $(2)_{V}$ . There, the $S^{2}$ modes of neighboring solitons are anti-aligned, and these modes should propagate in the transverse direction of the lattice due to the interaction between the $S^{2}$ modes of neighboring solitons. In this paper, we calculate excitations including gapless NG modes and excited modes around non-Abelian and Abelian ( $η$ ) CSLs, and find three gapless NG modes with linear dispersion relations (type-A NG modes): two isospinons ( $S^{2}$ modes) and a phonon corresponding to the spontaneously broken vector SU $(2)_{V}$ and translational symmetries around the non-Abelian CSL, respectively, and only a phonon for the Abelian CSL because of the recovering SU $(2)_{V}$ . We also find in the deconfined phase that the dispersion relation of the isospinons becomes of the Dirac type, {\it i.~e.~} linear even at large momentum.
↳ hep-phhep-thnucl-thJHEP(2024)·21 citations
21
Acausality in truncated 'MIS'-type theory
Sukanya Mitra🇮🇳
The causal-stable Muller-Israel-Stewart (MIS) theory is known to have a finite number of out of equilibrium derivative order corrections but requires treating the viscosity tensor as a separate degree of freedom with its own equations of motion, apart from the fundamental fluid degrees of freedom like velocity and temperature. In this work, I will show that it is possible to rewrite the MIS theory only in terms of velocity and temperature, but the resultant constitutive relation for dissipation must include all orders of gradient corrections. In this work I will argue that an all-order resummation of gradient contributions is equivalent to introducing new `non-fluid' degrees of freedom in the MIS theory. It will also be shown, using the relativistic quantum causality condition, that any finitely truncated order of derivative correction, however high it is, leads to a theory that is acausal, unless the corrections are infinitely summed up to all orders.
↳ gr-qchep-phhep-thnucl-thPRD(2024)·10 citations
22
Limiting attractors in heavy-ion collisions
Kirill Boguslavski🇦🇹 · Aleksi Kurkela🇳🇴 · Tuomas Lappi🇫🇮 · Florian Lindenbauer🇦🇹 · Jarkko Peuron🇫🇮
We study universal features of the hydrodynamization process in heavy-ion collisions using QCD kinetic theory simulations for a wide range of couplings. We introduce the new concept of limiting attractors, which are obtained by extrapolation to vanishing and strong couplings. While the hydrodynamic limiting attractor emerges at strong couplings and is governed by the viscosity-related relaxation time scale $τ_{R}$ , we identify a bottom-up limiting attractor at weak couplings. It corresponds to the late stages of the perturbative bottom-up thermalization scenario and exhibits isotropization on the time scale $τ_{BMSS} = α_{s}^{- 13/5} / Q_{s}$ . In contrast to hydrodynamic limiting attractors, at finite couplings the bottom-up limiting attractor provides a good universal description of the pre-hydrodynamic evolution of jet and heavy-quark momentum broadening ratios $q^^{y y} / q^^{z z}$ and $κ_{T} / κ_{z}$ . We also provide parametrizations for these ratios for phenomenological studies of pre-equilibrium effects on jets and heavy quarks.
↳ hep-phnucl-thPLB(2024)·29 citations
23
Measurement of the Isolated Nuclear Two-Photon Decay in $^{72} Ge$
D. Freire-Fernández🇩🇪 · W. Korten🇫🇷 · R. J. Chen🇩🇪 · S. Litvinov🇩🇪 · Yu. A. Litvinov🇩🇪 · M. S. Sanjari🇩🇪 · H. Weick🇩🇪 · F. C. Akinci🇹🇷 · H. M. Albers🇩🇪 · M. Armstrong🇩🇪 · A. Banerjee🇩🇪 · K. Blaum🇩🇪 and 48 other authors
The nuclear two-photon or double-gamma ( $2 γ$ ) decay is a second-order electromagnetic process whereby a nucleus in an excited state emits two gamma rays simultaneously. To be able to directly measure the $2 γ$ decay rate in the low-energy regime below the electron-positron pair-creation threshold, we combined the isochronous mode of a storage ring with Schottky resonant cavities. The newly developed technique can be applied to isomers with excitation energies down to $\sim 100$ \,keV and half-lives as short as $\sim 10$ \,ms. The half-life for the $2 γ$ decay of the first-excited $0^{+}$ state in bare $^{72} Ge$ ions was determined to be $23.9 (6)$ \,ms, which strongly deviates from expectations.
↳ nucl-exnucl-thPRL(2024)·15 citations
24
Simultaneous minijets and QGP evolution
Charles Gale🇨🇦 · Sangyong Jeon🇨🇦 · Daniel Pablos🇪🇸 · Mayank Singh🇺🇸
Minijets traversing through the QGP formed in heavy-ion collisions deposit significant amount of energy in the bulk medium. They also create gradients in temperatures which alter the flow profile and enhance entropy production. We study the effects of minijets in a simultaneous hydro + jet framework and find that inclusion of minijets requires recalibration of transport properties extracted from the model-to-data comparisons.
↳ hep-phnucl-thEPJ Web Conf.(2024)·0 citations
25
Enhanced contribution of the pairing gap to the QCD equation of state at large isospin chemical potential
Yuki Fujimoto🇺🇸
I study QCD at large isospin density, which is known to be in the superfluid state with Cooper pairs carrying the same quantum number as pions. I solve the gap equation derived from the perturbation theory up to the next-to-leading order corrections. The pairing gap at large isospin chemical potential is found to be enhanced compared to the color-superconducting gap at large baryon chemical potential due to the $2$ difference in the exponent arising from the stronger attraction in one-gluon exchange in the singlet channel. Then, using the gap function, I evaluate the contribution of the condensation energy of the superfluid state to the QCD equation of state. At isospin chemical potential of a few GeV, where the lattice QCD and the perturbative QCD can be both applied, the effect of the condensation energy becomes dominant even compared to the next-to-leading order corrections to the pressure in the perturbation theory. It resolves the discrepancy between the recent lattice QCD results and the perturbative QCD result.
↳ hep-phhep-latnucl-thPRD(2024)·25 citations

Affiliations

first authorsco-authorsvia INSPIRE