Nuclear Theory·nucl-th

Monday·October 7, 2024

7 papers—3 primary·4 cross-listed

01
QCD critical point: recent developments
Mikhail Stephanov🇺🇸
Recent developments aimed at mapping QCD phase diagram and the search for the QCD critical point in heavy-ion collisions are briefly reviewed.
nucl-thhep-phnucl-exEPJ Web Conf.(2024)·25 citations
02
Time-reversal invariance violation effect in $dd$ scattering
M.N. Platonova🇷🇺 · Yu.N. Uzikov🇷🇺
A formalism has been developed for calculating the signal of violation of $T$ invariance, provided that $P$ invariance is preserved during the scattering of tensor-polarized deuterons on vector-polarized ones based on the Glauber theory with the full consideration of spin dependence of $N N$ elastic scattering amplitudes and spin structure of colliding deuterons. The numerical calculations have been carried out in the range of laboratory proton energies $T_{p} = 0.1$ -- $1.2$ GeV using the SAID database for spin amplitudes and in the energy region of the SPD NICA experiment corresponding to the invariant mass of the interacting nucleon pairs $s_{N N} = 2.5$ -- $25$ GeV, using two phenomenological models of $pN$ elastic scattering. It is found that only one type of the $T$ non-invariant $P$ -invariant $N N$ interaction gives a non-zero contribution to the signal in question, that is important for isolating an unknown constant of this interaction from the corresponding data.
nucl-thCPC(2025)·3 citations
03
Mean-field approximation on steroids: exact description of the deuteron
B. Bally🇫🇷 · A. Scalesi🇫🇷 · V. Somà🇫🇷 · L. Zurek🇫🇷 · T. Duguet🇫🇷
The present article demonstrates that the deuteron, i.e. the lightest bound nuclear system made of a single proton and a single neutron, can be accurately described within a mean-field-based framework. Although paradoxical at first glance, the deuteron ground-state binding energy, magnetic dipole moment, electric quadrupole moment and root-mean-square proton radius are indeed reproduced with sub-percent accuracy via a low-dimensional linear combination of non-orthogonal Bogoliubov states, i.e. with a method whose numerical cost scales as $n_{dim}^{4}$ , where $n_{dim}$ is the dimension of the basis of the one-body Hilbert space. By further putting the system into a harmonic trap, the neutron-proton scattering length and effective range in the $^{3} S_{1}$ channel are also accurately reproduced. To achieve this task, (i) the inclusion of proton-neutron pairing through the mixing of proton and neutron single-particle states in the Bogoliubov transformation and (ii) the restoration of proton and neutron numbers before variation are shown to be mandatory ingredients. This unexpected result has implications regarding the most efficient way to capture necessary correlations as a function of nuclear mass and regarding the possibility to ensure order-by-order renormalizability of many-body calculations based on chiral or pionless effective field theories beyond light nuclei. In this context, the present study will be extended to $^{3}$ H and $^{3, 4}$ He in the near future as well as to the leading order of pionless effective field theory.
nucl-thEPJA(2025)·2 citations
04
Simplified projection on total spin zero for state preparation on quantum computers
Evan Rule🇺🇸 · Ionel Stetcu🇺🇸 · Joseph Carlson🇺🇸
We introduce a simple algorithm for projecting on $J = 0$ states of a many-body system by performing a series of rotations to remove states with angular momentum projections greater than zero. Existing methods rely on unitary evolution with the two-body operator $J^{2}$ , which when expressed in the computational basis contains many complicated Pauli strings requiring Trotterization and leading to very deep quantum circuits. Our approach performs the necessary projections using the one-body operators $J_{x}$ and $J_{z}$ . By leveraging the method of Cartan decomposition, the unitary transformations that perform the projection can be parameterized as a product of a small number of two-qubit rotations, with angles determined by an efficient classical optimization. Given the reduced complexity in terms of gates, this approach can be used to prepare approximate ground states of even-even nuclei by projecting onto the $J = 0$ component of deformed Hartree-Fock states. We estimate the resource requirements in terms of the universal gate set { $H$ , $S$ ,CNOT, $T$ } and briefly discuss a variant of the algorithm that projects onto $J = 1/2$ states of a system with an odd number of fermions.
↳ quant-phnucl-thPRC(2024)·6 citations
05
Recent developments in relativistic hydrodynamic fluctuations
Gokce Basar🇺🇸
The study of thermal fluctuations in relativistic hydrodynamics has led to numerous important developments in the last decade. We present a bird's eye view of the recent advances on the theory of fluctuations on three fronts; stochastic hydrodynamics, hydro-kinetics where fluctuations are included as additional modes that satisfy deterministic evolution equations, and effective field theory formulation of relativistic hydrodynamics. We compare and contrast these different but complimentary frameworks and highlight various recent progresses in each of them.
↳ hep-thnucl-thPPNP(2025)·18 citations
06
Light Nuclei Femtoscopy and Baryon Interactions in 3 GeV Au+Au Collisions at RHIC
The STAR Collaboration
We report the measurements of proton-deuteron ( $p$ - $d$ ) and deuteron-deuteron ( $d$ - $d$ ) correlation functions in Au+Au collisions at $s_{NN}$ = 3 GeV using fixed-target mode with the STAR experiment at the Relativistic Heavy-Ion Collider (RHIC). For the first time, the source size ( $R_{G}$ ), scattering length ( $f_{0}$ ), and effective range ( $d_{0}$ ) are extracted from the measured correlation functions with a simultaneous fit. The spin-averaged $f_{0}$ for $p$ - $d$ and $d$ - $d$ interactions are determined to be -5.28 $\pm$ 0.11(stat.) $\pm$ 0.82(syst.) fm and -2.62 $\pm$ 0.02(stat.) $\pm$ 0.24(syst.) fm, respectively. The measured $p$ - $d$ interaction is consistent with theoretical calculations and low-energy scattering experiment results, demonstrating the feasibility of extracting interaction parameters using the femtoscopy technique. The reasonable agreement between the experimental data and the calculations from the transport model indicates that deuteron production in these collisions is primarily governed by nucleon coalescence.
↳ nucl-exhep-exhep-phnucl-thPLB(2025)·20 citations
07
Moments of Axial-Vector GPD from Lattice QCD: Quark Helicity, Orbital Angular Momentum, and Spin-Orbit Correlation
Shohini Bhattacharya🇺🇸 · Krzysztof Cichy🇵🇱 · Martha Constantinou🇺🇸 · Xiang Gao🇺🇸 · Andreas Metz🇺🇸 · Joshua Miller🇺🇸 · Swagato Mukherjee🇺🇸 · Peter Petreczky🇺🇸 · Fernanda Steffens🇩🇪 · Yong Zhao🇺🇸
In this work, we present a lattice QCD calculation of the Mellin moments of the twist-2 axial-vector generalized parton distribution (GPD), $H (x, ξ, t)$ , at zero skewness, $ξ$ , with multiple values of the momentum transfer, $t$ . Our analysis employs the short-distance factorization framework on ratio-scheme renormalized quasi-GPD matrix elements. The calculations are based on an $N_{f} = 2 + 1 + 1$ twisted mass fermions ensemble with clover improvement, a lattice spacing of $a = 0.093$ fm, and a pion mass of $m_{π} = 260$ MeV. We consider both the iso-vector and iso-scalar cases, utilizing next-to-leading-order perturbative matching while omitting the disconnected contributions and gluon mixing in the iso-scalar case. For the first time, we determine the Mellin moments of $H$ up to the fifth order. From these moments, we discuss the quark helicity and orbital angular momentum contributions to the nucleon spin, as well as the spin-orbit correlations of the quarks. Additionally, we perform a Fourier transform over the momentum transfer, which allows us to explore the spin structure in the impact-parameter space.
↳ hep-lathep-exhep-phnucl-thJHEP(2025)·29 citations

Affiliations

first authorsco-authorsvia INSPIRE

QCD critical point: recent developments

Time-reversal invariance violation effect in dd scattering

Mean-field approximation on steroids: exact description of the deuteron

Simplified projection on total spin zero for state preparation on quantum computers

Recent developments in relativistic hydrodynamic fluctuations

Light Nuclei Femtoscopy and Baryon Interactions in 3 GeV Au+Au Collisions at RHIC

Moments of Axial-Vector GPD from Lattice QCD: Quark Helicity, Orbital Angular Momentum, and Spin-Orbit Correlation

Affiliations

Time-reversal invariance violation effect in $dd$ scattering