Nuclear Theory·nucl-th

Friday·December 29, 2023

22 papers—10 primary·12 cross-listed

11
Accelerated quantum circuit Monte-Carlo simulation for heavy quark thermalization
Xiaojian Du🇪🇸 · Wenyang Qian🇪🇸
Thermalization of heavy quarks in the quark-gluon plasma (QGP) is one of the most promising phenomena for understanding the strong interaction. The energy loss and momentum broadening at low momentum can be well described by a stochastic process with drag and diffusion terms. Recent advances in quantum computing, in particular quantum amplitude estimation (QAE), promise to provide a quadratic speed-up in simulating stochastic processes. We introduce and formalize an accelerated quantum circuit Monte-Carlo (aQCMC) framework to simulate heavy quark thermalization. With simplified drag and diffusion coefficients connected by Einstein's relation, we simulate the thermalization of a heavy quark in isotropic and anisotropic mediums using an ideal quantum simulator and compare that to thermal expectations. With Grover-like QAE, we calculate physical observables with quadratically fewer resources, which is a boost over the classical MC simulation that usually requires a large sampling number at the same estimation accuracy.
↳ hep-phnucl-thquant-phPRD(2024)·15 citations
12
Convergence of Ginzburg-Landau expansions: superconductivity in the Bardeen-Cooper-Schrieffer theory and chiral symmetry breaking in the Nambu-Jona-Lasinio model
William Gyory🇺🇸 · Naoki Yamamoto🇯🇵
We study the convergence of the Ginzburg-Landau (GL) expansion in the context of the Bardeen-Cooper-Schrieffer (BCS) theory for superconductivity and the Nambu-Jona-Lasinio (NJL) model for chiral symmetry breaking at finite temperature $T$ and chemical potential $μ$ . We present derivations of the all-order formulas for the coefficients of the GL expansions in both systems under the mean-field approximation. We show that the convergence radii for the BCS gap $Δ$ and dynamical quark mass $M$ are given by $Δ_{conv} = π T$ and $M_{conv} = μ^{2} + (π T)^{2}$ , respectively. We also discuss the implications of these results and the quantitative reliability of the GL expansion near the first-order chiral phase transition.
↳ hep-thcond-mat.supr-conhep-phnucl-thPTEP(2024)·1 citation
13
Analytic continuation of the finite-volume three-particle amplitudes
Sebastian M. Dawid🇺🇸
One has to study multivariable scattering amplitudes to extract properties of the three-body states from the generalizations of the Lüscher finite-volume formalism. In particular, a three-body amplitude obtained from a Lattice QCD calculation must be analytically continued to unphysical Riemann sheets of the complex energy plane, where resonances of interest appear as poles. In this article, we provide a pedagogical overview of a method for solving and analytically continuing the on-shell integral equations describing a three-body elastic scattering process. We illustrate the procedure by applying it to a relativistic system of three identical bosons characterized by pair-wise interactions. We describe the analytic structure of the reaction amplitude, show how to access its physical and unphysical Riemann sheets, and analyze the behavior of the three-body spectrum under variations of the interaction parameters.
↳ hep-latnucl-thPoS(2024)·2 citations
14
The Transverse Energy-Energy Correlator at Next-to-Next-to-Next-to-Leading Logarithm
Anjie Gao🇺🇸 · Hai Tao Li🇨🇳 · Ian Moult🇺🇸 · Hua Xing Zhu🇨🇳
We present an operator based factorization formula for the transverse energy-energy correlator in the back-to-back (dijet) region, and uncover its remarkable perturbative simplicity and relation to transverse momentum dynamics. This simplicity enables us to achieve next-to-next-to-next-to leading logarithmic (N $^{3}$ LL) accuracy for a hadron collider dijet event shape for the first time. Our factorization formula applies to color singlet, $W / Z / γ$ + jet, and dijet production, providing a natural generalization of transverse momentum observables to one- and two-jet final states. This provides a laboratory for precision studies of QCD and transverse momentum dynamics at hadron colliders, as well as an opportunity for understanding factorization and its violation in a perturbatively well controlled setting.
↳ hep-phnucl-thJHEP(2024)·40 citations
15
Field redefinitions and evolutions in relativistic Navier-Stokes
Yago Bea🇪🇸 · Pau Figueras🇬🇧
In recent years the equations of relativistic first-order viscous hydrodynamics, that is, the relativistic version of Navier-Stokes, have been shown to be well posed and causal under appropriate field redefinitions, also known as hydrodynamic frames. We perform real-time evolutions of these equations for a conformal fluid and explore, quantitatively, the consequences of using different causal frames for different sets of initial data. By defining specific criteria, we make precise and provide evidence for the statement that the arbitrarily chosen frame does not affect the physics up to first order, as long as the system is in the effective field theory regime. Motivated by the physics of the quark-gluon plasma created in heavy-ion collisions we also explore systems which are marginally in the effective field theory regime, finding that even under these circumstances the first order physics is robust under field redefinitions.
↳ hep-thastro-ph.HEgr-qcnucl-thJHEP(2024)·13 citations
16
QCD material parameters at zero and non-zero chemical potential from the lattice
D. A. Clarke🇺🇸 · J. Goswami🇯🇵 · F. Karsch🇩🇪 · P. Petreczky🇺🇸
Using an eighth-order Taylor expansion in baryon chemical potential, we recently obtained the (2+1)-flavor QCD equation of state (EoS) at non-zero conserved charge chemical potentials from the lattice. We focused on strangeness-neutral, isospin-symmetric QCD matter, which closely resembles the situation encountered in heavy-ion collision experiments. Using this EoS, we present here results on various QCD material parameters; in particular we compute the specific heat, speed of sound, and compressibility along appropriate lines of constant physics. We show that in the entire range relevant for the beam energy scan at RHIC, the specific heat, speed of sound, and compressibility show no indication for an approach to critical behavior that one would expect close to a possibly existing critical endpoint.
↳ hep-latnucl-thEPJ Web Conf.(2024)·0 citations
17
$e^{+} e^{-} \to Λ_{c}^{+} Λ ˉ_{c}^{-}$ cross sections and the $Λ_{c}^{+}$ electromagnetic form factors within the extended vector meson dominance model
Cheng Chen🇨🇳 · Bing Yan🇨🇳 · Ju-Jun Xie🇨🇳
Within the extended vector meson dominance model, we investigate the $e^{+} e^{-} \to Λ_{c}^{+} Λ ˉ_{c}^{-}$ reaction and the electromagnetic form factors of the charmed baryon $Λ_{c}^{+}$ . The model parameters are determined by fitting them to the cross sections of the process $e^{+} e^{-} \to Λ_{c}^{+} Λ ˉ_{c}^{-}$ and the magnetic form factor $∣ G_{M} ∣$ of $Λ_{c}^{+}$ . By considering four charmoniumlike states, called $ψ (4500)$ , $ψ (4660)$ , $ψ (4790)$ , and $ψ (4900)$ , we can well describe the current data on the $e^{+} e^{-} \to Λ_{c}^{+} Λ ˉ_{c}^{-}$ reaction from the reaction threshold up to $4.96 GeV$ . In addition to the total cross sections and $∣ G_{M} ∣$ , the ratio $∣ G_{E} / G_{M} ∣$ and effective form factor $∣ G_{eff} ∣$ for $Λ_{c}^{+}$ are also calculated, and found that these calculations are consistent with the experimental data. Within the fitted model parameters, we have also estimated the charge radius of the charmed $Λ_{c}^{+}$ baryon.
↳ hep-phhep-exnucl-exnucl-thChin.Phys.Lett.(2024)·15 citations
18
Search for the 6 $α$ condensed state in $^{24}$ Mg using the $^{12} C +^{12} C$ scattering
Y. Fujikawa · T. Kawabata · S. Adachi · S. Enyo · T. Furuno · Y. Hijikata · K. Himi · K. Hirose · Y. Honda · K. Inaba · H. Makii · K. Miyamoto and 9 other authors
We searched for the 6 $α$ -condensed state in $^{24}$ Mg by measuring the $^{12} C +^{12} C$ scattering with the SAKRA Si detector array at $E_\rm{cm}$ = 17.5-25.0 MeV. By using the invariant-mass method for the detected 3 $α$ particles, the inclusive cross sections for the $^{12} C +^{12} C \to^{12} C (0_{2}^{+}) + X$ and $^{12} C (3_{1}^{-}) + X$ reactions were determined. In addition, the missing-mass spectroscopy was successfully utilized to determine the excitation energy of the residual $^{12} C$ nucleus and the exclusive cross sections for the $^{12} C +^{12} C \to^{12} C (0_{2}^{+}) +^{12} C (0_{1}^{+})$ , $^{12} C (0_{2}^{+}) +^{12} C (2_{1}^{+})$ , and $^{12} C (0_{2}^{+}) +^{12} C (0_{2}^{+})$ reactions. In both the inclusive $^{12} C (0_{2}^{+}) + X$ channel and the exclusive $^{12} C (0_{2}^{+}) +^{12} C (0_{1}^{+})$ channel, the cross section peaked at $E_{r} m c m$ = 19.4 MeV, which correspond to the excitation energy of $E_{x}$ = 33.3 MeV in $^{24} Mg$ . This 19.4-MeV state is a candidate for the 6 $α$ -condensed state because of the agreement of the excitation energy with the theoretical value and its decay property. In the exclusive $^{12} C (0_{2}^{+}) +^{12} C (0_{2}^{+})$ channel, a broad state was observed at $E_\rm{cm}$ = 22.5 MeV, which correspond to the excitation energy of $E_{x}$ = 36.4 MeV in $^{24} Mg$ . From the angular distribution of the differential cross section, the spin and parity of this 22.5-MeV state was assigned to be $4^{+}$ . In addition, a $2^{+}$ state was suggested at the low-energy side of the 22.5-MeV state. Because their excitation energies are higher than the theoretical value of the 6 $α$ -condensed state, these states might be excited states of the 6 $α$ -condensed state such as the $2_{2}^{+}$ and $4_{1}^{+}$ states in $^{12} C$ .
↳ nucl-exnucl-thPLB(2024)·12 citations
19
Higgs-Confinement Transitions in QCD from Symmetry Protected Topological Phases
Thomas T. Dumitrescu🇺🇸 · Po-Shen Hsin🇺🇸
In gauge theories with fundamental matter there is typically no sharp way to distinguish confining and Higgs regimes, e.g. using generalized global symmetries acting on loop order parameters. It is standard lore that these two regimes are continuously connected, as has been explicitly demonstrated in certain lattice and continuum models. We point out that Higgsing and confinement sometimes lead to distinct symmetry protected topological (SPT) phases -- necessarily separated by a phase transition -- for ordinary global symmetries. We present explicit examples in 3+1 dimensions, obtained by adding elementary Higgs fields and Yukawa couplings to QCD while preserving parity P and time reversal T. In a suitable scheme, the confining phases of these theories are trivial SPTs, while their Higgs phases are characterized by non-trivial P- and T-invariant theta-angles $θ_{f}, θ_{g} = π$ for flavor or gravity background gauge fields, i.e. they are topological insulators or superconductors. Finally, we consider conventional three-flavor QCD (without elementary Higgs fields) at finite $U (1)_{B}$ baryon-number chemical potential $μ_{B}$ , which preserves P and T. At very large $μ_{B}$ , three-flavor QCD is known to be a completely Higgsed color superconductor that also spontaneously breaks $U (1)_{B}$ . We argue that this high-density phase is in fact a gapless SPT, with a gravitational theta-angle $θ_{g} = π$ that safely co-exists with the $U (1)_{B}$ Nambu-Goldstone boson. We explain why this SPT motivates unexpected transitions in the QCD phase diagram, as well as anomalous surface modes at the boundary of quark-matter cores inside neutron stars.
↳ hep-thcond-mat.str-elhep-lathep-ph+1SciPost Phys.(2024)·27 citations
20
Light-by-Light Scattering at Next-to-Leading Order in QCD and QED
Ajjath A H🇫🇷 · Ekta Chaubey🇩🇪 · Mathijs Fraaije🇨🇭 · Valentin Hirschi🇨🇭 · Hua-Sheng Shao🇫🇷
The recent experimental observation of Light-by-Light (LbL) scattering at the Large Hadron Collider has revived interest in this fundamental process, and especially of the accurate prediction of its cross-section, which we present here for the first time at Next-to-Leading Order (NLO) in both QCD and QED. We compare two radically different computational approaches, both exact in the fermion mass dependence, thus offering a strong cross-check of our results. The first approach is a fully analytic method to calculate compact and well-organized two-loop helicity amplitudes. The second one is entirely numerical and leverages the Local Unitarity construction. Our two calculations agree with each other and conclude that including the exact fermion mass contribution typically increases the size of the NLO corrections. Moreover, we find that the exact result converges slowly to the massless limit of the high-energy regime, thus emphasizing the importance of including the full mass dependence at NLO. We also compare our results with the ATLAS measurement of LbL in ultra-peripheral lead-lead collisions, and find that the inclusion of exact NLO corrections reduces, but does not eliminate, the existing tension with theoretical predictions.
↳ hep-phhep-exhep-thnucl-ex+1PLB(2024)·33 citations
21
Mass spectrum of spin-one hadrons in dense two-color QCD: Novel predictions by extended linear sigma model
Daiki Suenaga🇯🇵 · Kotaro Murakami🇯🇵 · Etsuko Itou🇯🇵 · Kei Iida🇯🇵
We construct an extended version of the linear sigma model in such a way as to describe spin- $1$ hadrons as well as spin- $0$ hadrons in two-color QCD (QC $_{2}$ D) by respecting the Pauli-Gürsey $S U (4)$ symmetry. Within a mean-field approximation, we therefrom examine a mass spectrum of the spin- $1$ hadrons at finite quark chemical potential ( $μ_{q}$ ) and zero temperature. Not only mean fields of scalar mesons and scalar-diquark baryons but also of vector mesons and vector-diquark baryons are incorporated. As a result, we find that, unless all of those four types of mean fields are taken into account, neither lattice result for the critical $μ_{q}$ that corresponds to the onset of baryon superfluidity nor for $μ_{q}$ dependence of the pion mass can be reproduced. We also find that a slight suppression of the $ρ$ meson mass in the superfluid phase, which was suggested by the lattice simulation, is reproduced by subtle mixing effects between spin- $0$ and spin- $1$ hadrons. Moreover, we demonstrate the emergence of an axialvector condensed phase and possibly of a vector condensed phase by identifying the values of $μ_{q}$ at which the corresponding hadron masses vanish. The possible presence of iso-triplet $1^{-}$ diquarks that may be denoted by a tensor-type quark bilinear field is also discussed.
↳ hep-phhep-latnucl-thPRD(2024)·14 citations
22
Static force from generalized Wilson loops on the lattice using the gradient flow
Nora Brambilla🇩🇪 · Viljami Leino🇩🇪 · Julian Mayer-Steudte🇩🇪 · Antonio Vairo🇩🇪
The static QCD force from the lattice can be used to extract $Λ_{MS}$ , which determines the running of the strong coupling. Usually, this is done with a numerical derivative of the static potential. However, this introduces additional systematic uncertainties; thus, we use another observable to measure the static force directly. This observable consists of a Wilson loop with a chromoelectric field insertion. We work in the pure SU(3) gauge theory. We use gradient flow to improve the signal-to-noise ratio and to address the field insertion. We extract $Λ_{MS}^{n_{f} = 0}$ from the data by exploring different methods to perform the zero-flow-time limit. We obtain the value $8 t_{0} Λ_{MS}^{n_{f} = 0} = 0.62 9_{- 26}^{+ 22}$ , where $t_{0}$ is a flow-time reference scale. We also obtain precise determinations of several scales: $r_{0} / r_{1}$ , $8 t_{0} / r_{0}$ , $8 t_{0} / r_{1}$ and we compare these to the literature. The gradient flow appears to be a promising method for calculations of Wilson loops with chromoelectric and chromomagnetic insertions in quenched and unquenched configurations
↳ hep-lathep-phhep-thnucl-thPRD(2024)·17 citations

Affiliations

first authorsco-authorsvia INSPIRE