Nuclear Theory·nucl-th

Friday·September 23, 2022

15 papers—7 primary·8 cross-listed

08
Chiral spin symmetry and hot/dense QCD
L. Ya. Glozman🇦🇹
Above the chiral symmetry restoration crossover around T_{ch} ~ 155 MeV a new regime arises in QCD, a stringy fluid, which is characterized by an approximate chiral spin symmetry of the thermal partition function. This symmetry is not a symmetry of the Dirac Lagrangian and is a symmetry of the electric part of the QCD Lagrangian. In this regime the medium consists of the chirally symmetric and approximately chiral spin symmetric hadrons that are made of the chirally symmetric quarks connected into the color singlet compounds by a confining chromoelectric field. This regime is evidenced by the approximate chiral spin symmetry of the spatial and temporal correlators and by the breakdown of the thermal perturbation theory at the crossover between the partonic (the quark-gluon plasma) and stringy fluid regimes at ~ 3 T_{ch}. The chiral spin symmetry smoothly disappears above ~ 3T_{ch} which means that the chromoelectric confining interaction gets screened. A direct evidence that the stringy fluid medium consists of densely packed hadrons is the pion spectral function that shows a distinct pion state and its first radial excitation above T_{ch}. Another direct evidence of the hadron degrees of freedom in the stringy fluid is the bottomonium spectrum with the 1S,2S,3S and 1P,2P radial and orbital excitations that become broad with temperature. The hadrons between T_{ch} and ~ 3 T_{ch} in the stringy fluid interact strongly which makes the stringy fluid more a liquid rather than a gas. We discuss how this chiral spin symmetric regime extends into the finite chemical potentials domain and present a qualitative sketch of the QCD phase diagram.
↳ hep-lathep-phhep-thnucl-ex+1PPNP(2023)·35 citations
09
Coupled-channel dynamics with chiral long-range forces in the open-charm sector of QCD
Matthias F.M. Lutz🇩🇪 · Xiao-Yu Guo🇨🇳 · Yonggoo Heo🇩🇪 · C.L. Korpa🇭🇺
We perform an analysis of Lattice QCD data in the open-charm sector based on the chiral SU(3) Lagrangian. The low-energy constants are adjusted to recover the open-charm meson masses on Lattice QCD ensembles from HPQCD, ETMC and HSC with pion and kaon masses smaller than 550 MeV. A significant set of low-energy parameters is obtainable only if the most recent information from HSC on scattering observables is included in our global fit. For the first time our analysis considers the effect of left-hand cuts as developed in terms of a generalized potential approach (GPA) previously by one of the authors. Here we use coupled-channel interaction terms at the one-loop level. The elastic s-wave and p-wave $D π$ , $D K$ and $D K ˉ$ scattering phase shifts on ensembles with nominal pion masses of about 239 MeV and 391 MeV are reproduced faithfully. Based on such low-energy parameters we predict s- and p-wave phase shifts and inelasticities at physical quark masses, where the statistical uncertainties in the phase shifts are smaller than 1 degree always. Most striking would be the exotic s-wave $D_{s} π$ channel, for which we predict a resonance state at about 2.287 GeV where the phase shift passes through 90 degrees.
↳ hep-phhep-latnucl-thPRD(2022)·17 citations
10
Report of the Snowmass 2021 Topical Group on Lattice Gauge Theory
Zohreh Davoudi🇺🇸 · Ethan T. Neil🇺🇸 · Christian W. Bauer🇺🇸 · Tanmoy Bhattacharya🇺🇸 · Thomas Blum🇺🇸 · Peter Boyle🇺🇸 · Richard C. Brower🇺🇸 · Simon Catterall🇺🇸 · Norman H. Christ🇺🇸 · Vincenzo Cirigliano🇺🇸 · Gilberto Colangelo🇨🇭 · Carleton DeTar🇺🇸 and 26 other authors
Lattice gauge theory continues to be a powerful theoretical and computational approach to simulating strongly interacting quantum field theories, whose applications permeate almost all disciplines of modern-day research in High-Energy Physics. Whether it is to enable precision quark- and lepton-flavor physics, to uncover signals of new physics in nucleons and nuclei, to elucidate hadron structure and spectrum, to serve as a numerical laboratory to reach beyond the Standard Model, or to invent and improve state-of-the-art computational paradigms, the lattice-gauge-theory program is in a prime position to impact the course of developments and enhance discovery potential of a vibrant experimental program in High-Energy Physics over the coming decade. This projection is based on abundant successful results that have emerged using lattice gauge theory over the years: on continued improvement in theoretical frameworks and algorithmic suits; on the forthcoming transition into the exascale era of high-performance computing; and on a skillful, dedicated, and organized community of lattice gauge theorists in the U.S. and worldwide. The prospects of this effort in pushing the frontiers of research in High-Energy Physics have recently been studied within the U.S. decadal Particle Physics Planning Exercise (Snowmass 2021), and the conclusions are summarized in this Topical Report.
↳ hep-lathep-phhep-thnucl-th46 citations
11
Preparations for Quantum Simulations of Quantum Chromodynamics in 1+1 Dimensions: (II) Single-Baryon $β$ -Decay in Real Time
Roland C. Farrell🇺🇸 · Ivan A. Chernyshev🇺🇸 · Sarah J. M. Powell🇨🇦 · Nikita A. Zemlevskiy🇺🇸 · Marc Illa🇺🇸 · Martin J. Savage🇺🇸
A framework for quantum simulations of real-time weak decays of hadrons and nuclei in a 2-flavor lattice theory in one spatial dimension is presented. A single generation of the Standard Model is found to require 16 qubits per spatial lattice site after mapping to spin operators via the Jordan-Wigner transformation. Both quantum chromodynamics and flavor-changing weak interactions are included in the dynamics, the latter through four-Fermi effective operators. Quantum circuits which implement time evolution in this lattice theory are developed and run on Quantinuum's H1-1 20-qubit trapped ion system to simulate the $β$ -decay of a single baryon on one lattice site. These simulations include the initial state preparation and are performed for both one and two Trotter time steps. The potential intrinsic error-correction properties of this type of lattice theory are discussed and the leading lattice Hamiltonian required to simulate $0 ν β β$ -decay of nuclei induced by a neutrino Majorana mass term is provided.
↳ quant-phhep-lathep-phnucl-thPRD(2023)·130 citations
12
Parameterisations of thermal bomb explosions for core-collapse supernovae and 56Ni production
Liliya Imasheva (1,2) · H.-Thomas Janka (1,3) · Achim Weiss (1,2) ((1) MPI Astrophysics, Garching, (2) LMU, Munich, (3) TUM, Garching)
Thermal bombs are a widely used method to artificially trigger explosions of core-collapse supernovae (CCSNe) to determine their nucleosynthesis or ejecta and remnant properties. Recently, their use in spherically symmetric (1D) hydrodynamic simulations led to the result that {56,57}Ni and 44Ti are massively underproduced compared to observational estimates for Supernova 1987A, if the explosions are slow, i.e., if the explosion mechanism of CCSNe releases the explosion energy on long timescales. It was concluded that rapid explosions are required to match observed abundances, i.e., the explosion mechanism must provide the CCSN energy nearly instantaneously on timescales of some ten to order 100 ms. This result, if valid, would disfavor the neutrino-heating mechanism, which releases the CCSN energy on timescales of seconds. Here, we demonstrate by 1D hydrodynamic simulations and nucleosynthetic post-processing that these conclusions are a consequence of disregarding the initial collapse of the stellar core in the thermal-bomb modelling before the bomb releases the explosion energy. We demonstrate that the anti-correlation of 56Ni yield and energy-injection timescale vanishes when the initial collapse is included and that it can even be reversed, i.e., more 56Ni is made by slower explosions, when the collapse proceeds to small radii similar to those where neutrino heating takes place in CCSNe. We also show that the 56Ni production in thermal-bomb explosions is sensitive to the chosen mass cut and that a fixed mass layer or fixed volume for the energy deposition cause only secondary differences. Moreover, we propose a most appropriate setup for thermal bombs.
↳ astro-ph.HEhep-phnucl-thMNRAS(2022)·13 citations
13
Imaging the initial condition of heavy-ion collisions and nuclear structure across the nuclide chart
Jiangyong Jia🇺🇸 · Giuliano Giacalone🇩🇪 · Benjamin Bally🇫🇷 · James Daniel Brandenburg🇺🇸 · Ulrich Heinz🇺🇸 · Shengli Huang🇺🇸 · Dean Lee🇺🇸 · Yen-Jie Lee🇺🇸 · Wei Li🇺🇸 · Constantin Loizides🇺🇸 · Matthew Luzum🇧🇷 · Govert Nijs🇺🇸 and 9 other authors
High-energy nuclear collisions encompass three key stages: the structure of the colliding nuclei informed by low-energy nuclear physics, the initial condition (IC) leading to the formation of quark-gluon plasma (QGP), and the hydrodynamic expansion and hadronization of the QGP leading to final-state hadrons observed experimentally. Recent advances in experimental and theoretical methods have ushered in a precision era, enabling an increasingly accurate understanding of these stages. However, most approaches involve simultaneously determining both QGP properties and initial conditions from a single collision system, creating complexity due to the coupled contributions of various stages to the final-state observables. To avoid this, we propose leveraging known knowledge of low-energy nuclear structure and hydrodynamic observables to constrain the IC independently. By conducting comparative studies of collisions involving isobar-like nuclei - species with similar mass numbers but different structures - we disentangle the initial condition's impacts from the QGP properties. This approach not only refines our understanding of the IC but also turns high-energy experiments into a precision tool for imaging nuclear structures, offering insights that complement traditional low-energy approaches. Opportunities for carrying out such comparative experiments at the LHC and other facilities could significantly advance both high-energy and low-energy nuclear physics. Additionally, this approach has implications for the future EIC. While the possibilities are extensive, we focus on selected proposals that could benefit both the high-energy and low-energy nuclear physics communities. Originally prepared as input for the long-range plan of U.S. nuclear physics, this white paper reflects the status as of September 2022, with a brief update on developments since then.
↳ nucl-exhep-phnucl-thNucl.Sci.Tech.(2024)·128 citations
14
Kinematical higher-twist corrections in $γ^{*} γ \to M M ˉ$
Cédric Lorcé🇫🇷 · Bernard Pire🇫🇷 · Qin-Tao Song🇫🇷
We estimate kinematical higher-twist (up to twist 4) corrections to the $γ^{*} (q_{1}) γ (q_{2}) \to M (p_{1}) M ˉ (p_{2})$ amplitudes at large $Q^{2} = - q_{1}^{2}$ and small $s = (q_{1} + q_{2})^{2}$ , where $M$ is a scalar or pseudoscalar meson. This process is known to factorize at leading twist into a perturbatively calculable coefficient function and generalized distribution amplitudes (GDAs). The kinematical higher-twist contributions of order $s / Q^{2}$ and $m^{2} / Q^{2}$ turn out to be important in the cross section, considering the kinematics accessible at Belle and Belle II. We present numerical estimates for the cross section for $γ^{*} γ \to π^{0} π^{0}$ with the $π π$ GDA extracted from Belle measurements and with the asymptotic $π π$ GDA as inputs to study the magnitude of the kinematical corrections. To see how the target mass corrections of order $m^{2} / Q^{2}$ affect the cross section, we also perform the calculation for $γ^{*} γ \to η η$ by using a model $η η$ GDA.In the range $s > 1$ GeV $^{2}$ , the kinematical higher-twist corrections account for $\sim 15%$ of the total cross section, an effect which is not negligible. Since $π π$ GDAs are the best way to access the pion energy-momentum tensor (EMT), our study demonstrates that an accurate evaluation of EMT form factors requires the inclusion of kinematical higher-twist contributions.
↳ hep-phnucl-thPRD(2022)·17 citations
15
A Better Angle on Hadron Transverse Momentum Distributions at the EIC
Anjie Gao🇺🇸 · Johannes K. L. Michel🇺🇸 · Iain W. Stewart🇺🇸 · Zhiquan Sun🇺🇸
We propose an observable $q_{*}$ sensitive to transverse momentum dependence (TMD) in $e N \to e h X$ , with $q_{*} / E_{N}$ defined purely by lab-frame angles. In 3D measurements of confinement and hadronization this resolves the crippling issue of accurately reconstructing small transverse momentum $P_{h T}$ . We prove factorization for $d σ_{h} / d q_{*}$ for $q_{*} ≪ Q$ with standard TMD functions, enabling $q_{*}$ to substitute for $P_{h T}$ . A double-angle reconstruction method is given which is exact to all orders in QCD for $q_{*} ≪ Q$ . $q_{*}$ enables an order-of-magnitude improvement in the expected experimental resolution at the EIC.
↳ hep-phnucl-exnucl-thPRD(2023)·16 citations

Affiliations

first authorsco-authorsvia INSPIRE