Nuclear Theory·nucl-th

Monday·November 28, 2022

22 papers—12 primary·10 cross-listed

13
A study of the relativistic corrections to polarized tritium $β$ -decay
Gianluca Cavoto🇮🇹 · Angelo Esposito🇮🇹 · Guglielmo Papiri🇮🇹 · Antonio Davide Polosa🇮🇹
Forthcoming experiments like Project8 and Ptolemy aim at investigating with high precision the end-point of the tritium $β$ -decay spectrum sensitive to the neutrino mass. In light of this, using the standard parametrization in terms of nuclear polar form factors, we analyze the complete relativistic expression for the spectrum of the $β$ -electron emitted by a tritium nucleus. Given the small parameters in the problem, we systematically discuss the approximations that can be made, and present the first two corrections to the standard lowest order formula. We particularly discuss the case of an initially polarized target, and the consequences on the spectrum as a function of the neutrino mass. We show that, while it induces an angular anisotropy that can be measured by future experiments, such anisotropy cannot be used as an additional handle to constrain the neutrino mass.
↳ hep-phnucl-thPRC(2023)·3 citations
14
Entropy Suppression through Quantum Interference in Electric Pulses
Gerald V. Dunne🇺🇸 · Adrien Florio🇺🇸 · Dmitri E. Kharzeev🇺🇸
The Schwinger process in strong electric fields creates particles and antiparticles that are entangled. The entropy of entanglement between particles and antiparticles has been found to be equal to the statistical Gibbs entropy of the produced system. Here we study the effect of quantum interference in sequences of electric pulses, and show that quantum interference suppresses the entanglement entropy of the created quantum state. This is potentially relevant to quantum-enhanced classical communications. Our results can be extended to a wide variety of two-level quantum systems.
↳ hep-phhep-thnucl-thquant-phPRD(2023)·8 citations
15
Dynamical fermions, centre vortices, and emergent phenomena
Derek Leinweber🇦🇺 · James Biddle🇦🇺 · Waseem Kamleh🇦🇺 · Adam Virgili (CSSM, University of Adelaide)🇦🇺
The non-trivial ground-state vacuum fields of QCD form the foundation of matter. Here we examine the centre vortices identified within the ground-state fields of lattice QCD. We aim to understand the manner in which dynamical fermions in the QCD vacuum alter the centre-vortex structure. Using modern visualisation techniques, the centre-vortex structure of pure-gauge and dynamical-fermion fields is quantified and compared. We then explore the impact this modified structure has on measures of confinement and dynamical mass generation. The string tension of the static quark potential, positivity-violation in the gluon propagator, and dynamical mass generation in the overlap quark propagator are of particular interest. The impact of dynamical fermions is significant and provides new insights into the role of centre vortices in underpinning both confinement and dynamical chiral symmetry breaking in QCD.
↳ hep-lathep-phnucl-thEPJ Web Conf.(2022)·6 citations
16
Sea-quark loop contributions to the $d ˉ$ - $u ˉ$ asymmetry in the proton
Derek B. Leinweber🇦🇺 · Anthony W. Thomas (CSSM, University of Adelaide)🇦🇺
QCD interactions for equal-mass fermion flavors are flavor blind. This fact is often used to state that disconnected sea-quark loop contributions are equal for $u$ and $d$ quarks in the mass symmetric case and therefore these disconnected sea-quark loop contributions cannot contribute to the well-known $d ˉ - u ˉ$ asymmetry in the proton. Instead, it is argued that one must look to the connected sector of lattice QCD correlation functions to find this difference. In this presentation, we note that these statements are true provided unphysical contributions in the sea-quark loop sector are included, contributions from baryons that do not appear in the physical spectrum. To respect the Pauli principle, these unphysical contributions from the disconnected sea-quark loop sector must cancel equally unphysical contributions in the connected sector. The remaining disconnected sea-quark loop contributions no longer have a balance between $d ˉ$ and $u ˉ$ . Upon considering only physically observed baryons in the loop contributions, we illustrate an important contribution from the sea-quark loop sector to $d ˉ - u ˉ$ that enhances the leading connected contribution by 12\%.
↳ hep-phhep-latnucl-thPRD(2024)·4 citations
17
Measurement of hadron masses in 2-color finite density QCD
Kotaro Murakami🇯🇵 · Daiki Suenaga🇯🇵 · Kei Iida🇯🇵 · Etsuko Itou🇯🇵
We investigate hadron spectra in 2-color QCD using lattice simulation with $N_{f} = 2$ at low temperature and finite density in which there appears not only the hadronic phase but also the superfluid phase. We first calculate the pion and rho meson spectrum, which is well-known from previous works. The spectral ordering of these mesons flips around the quark chemical potential $μ = m_{π}^{0} /2$ ( $m_{π}^{0}$ : the pion mass at $μ = 0$ ), where the phase transition between the hadronic and superfluid phases occurs. For $μ ≳ m_{π}^{0} /2$ , the effective mass for the pion linearly increases while the one for the rho meson monotonically decreases. Furthermore, we measure hadron spectra with the isospin $I = 0$ and the angular momentum $J^{P} = 0^{\pm}$ . The effective masses for the meson, diquark, and antidiquark with the same quantum number become degenerate just below $μ = m_{π}^{0} /2$ , and the three hadrons have the same mass in the superfluid phase. It suggests that mixing occurs between spectra associating with mesons and baryons due to the $U (1)_{B}$ symmetry breaking. This phenomenon can be explained in the linear sigma model with the approximate $S U (4)$ Pauli-Gursey symmetry.
↳ hep-lathep-phnucl-thPoS(2023)·18 citations
18
Transverse momentum decorrelation of the flow vector in Pb-Pb collisions at $s_{NN}$ = 5.02 TeV
Emil Gorm Nielsen🇩🇰 · You Zhou🇩🇰
The individual studies of the anisotropic flow vector, flow angle and flow magnitude fluctuations with multi-particle correlations provide insight into the initial conditions and properties of the quark-gluon plasma (QGP) created in high-energy heavy-ion collisions. Recent measurements of these fluctuations have been available and the comparison to hydrodynamic models shows unique sensitivities to the initial conditions of the system, but also a puzzling dependence on the specific shear viscosity $η / s$ . In this paper, a systematic study with A Multi-Phase Transport (AMPT) model using different tunings of the initial conditions, partonic cross section and hadronic interactions investigates the $p_{T}$ -dependent flow vector, flow angle and flow magnitude fluctuations. It is found that the transport model reasonably describes the flow vector, flow angle and flow magnitude fluctuations observed in data and that the fluctuations are driven by fluctuations in the initial state. The comparison of data and model presented in this paper enables further constraints on the initial conditions of the heavy-ion collisions.
↳ nucl-exnucl-thEPJC(2023)·12 citations
19
Helicity conservation in perfect electromagnetic and chiral fluids
Cristina Manuel🇪🇸 · Juan M. Torres-Rincon🇪🇸
We derive the total helicity conservation law for a perfect electromagnetic relativistic fluid. As the conservation equation contains the derivative of the magnetic helicity, it can be reshaped as having the same form as the chiral anomaly equation if the fluid is isentropic. We also take the non-relativistic limit of the helicity conservation law, and check the agreement with the Abanov-Wiegmann equation at zero temperature, but we provide further corrections in the more general case. We then consider chiral fluids, when the chiral anomaly equation has to be incorporated in the hydrodynamical equations, together with other chiral transport effects which exist in the presence of a chiral imbalance. We finally study how the chiral imbalance modifies the helicity conservation law.
↳ hep-phhep-thnucl-thPRD(2023)·4 citations
20
Hadrons at high temperature: an update from the FASTSUM collaboration
Jon-Ivar Skullerud🇮🇪 · Gert Aarts🇬🇧 · Chris Allton🇬🇧 · M. Naeem Anwar🇬🇧 · Ryan Bignell🇬🇧 · Tim Burns🇬🇧 · Sergio Chaves García-Mascaraque🇬🇧 · Simon Hands🇬🇧 · Rachel Horohan D'Arcy🇮🇪 · Benjamin Jäger🇩🇰 · Seyong Kim🇰🇷 · Maria Paola Lombardo🇮🇹 and 7 other authors
We present the most recent results from the FASTSUM collaboration for hadron properties at high temperature. This includes the temperature dependence of the light and charmed meson and baryon spectrum, as well as properties of heavy quarkonia. The results are obtained using anisotropic lattices with a fixed scale approach. We also present the status of our next generation gauge ensembles.
↳ hep-lathep-phnucl-thEPJ Web Conf.(2022)·7 citations
21
Inverse Problem Approach for Non-Perturbative QCD: Theoretical Foundation
Ao-Sheng Xiong🇨🇳 · Fu-Sheng Yu🇨🇳 · Yong Zheng🇨🇳 · Ting Wei🇨🇳
A novel theoretical framework, the inverse problem approach, is proposed to calculate non-perturbative quantities in quantum chromodynamics (QCD). Based on the dispersion relation of quantum field theory, this approach determines unknown low-energy non-perturbative quantities from known high-energy perturbative inputs via solving an inverse problem. The resulting inverse problem is rigorously proven to be ill-posed, with the solutions being unique but unstable. To address this instability, the well-established Tikhonov regularization is employed, yielding stable approximate solutions that converge to the true values as input errors vanish. The key features of this approach are illustrated through three toy models, demonstrating that solution precision can be systematically improved through reduced input errors and optimized regularization strategies.
↳ hep-thhep-exhep-lathep-ph+121 citations
22
Hidden-flavor pentaquarks
H. Garcilazo🇲🇽 · A. Valcarce🇪🇸
We have recently studied hidden-charm pentaquarks, $c c ˉ q q q$ , using dynamical correlations between the heavy quarks arising from the Coulomb-like nature of the short-range interaction. A pattern was obtained that compares well with the experimental data. We extend our description to other flavor sectors which can be framed within the same type of structures discussed in the original paper. A detailed comparison is made with other results in the literature and with experimental data. Predictions will be a useful tool to discriminate between different models of multiquark system dynamics.
↳ hep-phnucl-thPRD(2022)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE