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Neutron stars provide a unique opportunity to study strongly interactingmatter under extreme density conditions. The intricacies of matter insideneutron stars and their equation of state are not directly visible, butdetermine bulk properties, such as mass and radius, which affect the star'sthermal X-ray emissions. However, the telescope spectra of these emissions arealso affected by the stellar distance, hydrogen column, and effective surfacetemperature, which are not always well-constrained. Uncertainties on thesenuisance parameters must be accounted for when making a robust estimation ofthe equation of state. In this study, we develop a novel methodology that, forthe first time, can infer the full posterior distribution of both the equationof state and nuisance parameters directly from telescope observations. Thismethod relies on the use of neural likelihood estimation, in which normalizingflows use samples of simulated telescope data to learn the likelihood of theneutron star spectra as a function of these parameters, coupled withHamiltonian Monte Carlo methods to efficiently sample from the correspondingposterior distribution. Our approach surpasses the accuracy of previousmethods, improves the interpretability of the results by providing access tothe full posterior distribution, and naturally scales to a growing number ofneutron star observations expected in the coming years.

Recently, the EMPRESS collaboration has included new data in the extractionof the primordial $^4$He abundance from Big Bang Nucleosynthesis (BBN),resulting in a determination that differs from the previous value and fromtheoretical expectations. There have been several studies attempting to explainthis anomaly which involve variation of fundamental constants between the timeof BBN and the present. Since the Higgs vacuum expectation value (vev) is theonly dimensionful parameter in the Standard Model and it is already known tovary during the electroweak phase transition, we consider the possibility thatthe vev is slightly different during BBN compared to its present value. Amodification of the vev changes not only particle masses but also affects,through mass thresholds, the QCD confinement scale. We use the recentlydeveloped PRyMordial program to study this variation and its impact on the$^4$He and deuterium abundances. We find that bounds on $|{\delta v}/{v}|$ areapproximately $0.01$, and that the EMPRESS result can be explained within$2\sigma$ if $0.008 < {\delta v}/{v}< 0.02$, but at the cost of worsening thecurrent $2\sigma$ discrepancy in the deuterium abundance to over $3\sigma$.

We study the effects of the first nontrivial hexaquark, $d^*$(2380), on theequation of state of dense neutron star matter and investigate the consequencesof its existence for neutron stars. The matter in the core regions of neutronstars is described using density-dependent relativistic mean-field theory. Ourresults show that within the parameter spaces examined in our paper, (i) thecritical density at which the $d^*$ condensate emerges lies between 4 and 5times the nuclear saturation density, (ii) $d^*$ hexaquarks are found to existonly in rather massive neutron stars, (iii) only relatively small fractions ofthe matter in the core of a massive neutron star may contain hexaquarks.

Neutron stars may experience differential rotation on short, dynamicaltimescales following extreme astrophysical events like binary neutron starmergers. In this work, the masses and radii of differentially rotating neutronstar models are computed. We employ a set of equations of states for densehypernuclear and $\Delta$-admixed-hypernuclear matter obtained within theframework of CDF theory in the relativistic Hartree-Fock (RHF) approximation.Results are shown for varying meson-$\Delta$ couplings, or equivalently the$\Delta$-potential in nuclear matter. A comparison of our results with thoseobtained for non-rotating stars shows that the maximum mass difference betweendifferentially rotating and static stars is independent of the underlyingparticle composition of the star. We further find that the decrease in theradii and increase in the maximum masses of stellar models when$\Delta$-isobars are added to hyperonuclear matter (as initially observed forstatic and uniformly rotating stars) persist also in the case of differentiallyrotating neutron stars.

Fluctuations and correlations of the net-baryon number play an important rolein exploring critical phenomena in phase transitions of strongly interactingmatter governed by Quantum chromodynamics (QCD). In this work, we use theparity doublet model to investigate the fluctuations of the net-baryon numberdensity in hot and dense hadronic matter. The model accounts for chiralcriticality within the mean-field approximation. We focus on the qualitativeproperties and systematics of the first- and second-order susceptibility of thenet-baryon number density, and their ratios for nucleons of positive andnegative parity, as well as their correlator. We show that the fluctuations ofthe positive-parity nucleon do not necessarily reflect the fluctuations of thetotal net-baryon number density at the phase boundary of the chiral phasetransition. We also investigate the non-trivial structure of the correlator.Furthermore, we discuss and quantify the differences between the fluctuationsof the net-baryon number density in the vicinity of the chiral and liquid-gasphase transition in nuclear matter. We indicate a possible relevance of ourresults with the interpretation of the experimental data on net-proton numberfluctuations in heavy-ion collisions.

Hot QCD physics studies the nuclear strong force under extreme temperatureand densities. Experimentally these conditions are achieved via high-energycollisions of heavy ions at the Relativistic Heavy Ion Collider (RHIC) and theLarge Hadron Collider (LHC). In the past decade, a unique and substantial suiteof data was collected at RHIC and the LHC, probing hydrodynamics at the nucleonscale, the temperature dependence of the transport properties of quark-gluonplasma, the phase diagram of nuclear matter, the interaction of quarks andgluons at different scales and much more. This document, as part of the 2023nuclear science long range planning process, was written to review the progressin hot QCD since the 2015 Long Range Plan for Nuclear Science, as well ashighlight the realization of previous recommendations, and presentopportunities for the next decade, building on the accomplishments andinvestments made in theoretical developments and the construction of newdetectors. Furthermore, this document provides additional context to supportthe recommendations voted on at the Joint Hot and Cold QCD Town Hall Meeting,which are reported in a separate document.

This White Paper presents the community inputs and scientific conclusionsfrom the Hot and Cold QCD Town Meeting that took place September 23-25, 2022 atMIT, as part of the Nuclear Science Advisory Committee (NSAC) 2023 Long RangePlanning process. A total of 424 physicists registered for the meeting. Themeeting highlighted progress in Quantum Chromodynamics (QCD) nuclear physicssince the 2015 LRP (LRP15) and identified key questions and plausible paths toobtaining answers to those questions, defining priorities for our research overthe coming decade. In defining the priority of outstanding physicsopportunities for the future, both prospects for the short (~ 5 years) andlonger term (5-10 years and beyond) are identified together with thefacilities, personnel and other resources needed to maximize the discoverypotential and maintain United States leadership in QCD physics worldwide. ThisWhite Paper is organized as follows: In the Executive Summary, we detail theRecommendations and Initiatives that were presented and discussed at the TownMeeting, and their supporting rationales. Section 2 highlights major progressand accomplishments of the past seven years. It is followed, in Section 3, byan overview of the physics opportunities for the immediate future, and inrelation with the next QCD frontier: the EIC. Section 4 provides an overview ofthe physics motivations and goals associated with the EIC. Section 5 is devotedto the workforce development and support of diversity, equity and inclusion.This is followed by a dedicated section on computing in Section 6. Section 7describes the national need for nuclear data science and the relevance to QCDresearch.

We review the physics of hyperons and $\Delta$-resonances in dense matter incompact stars. The covariant density functional approach to the equation ofstate and composition of dense nuclear matter in the mean-field Hartree andHartree-Fock approximation is presented, with regimes covering cold$\beta$-equilibrated matter, hot and dense matter with and without neutrinosrelevant for the description of supernovas and binary neutron star mergers, aswell as dilute expanding nuclear matter in collision experiments. We discussthe static properties of compact stars with hyperons and $\Delta$-resonances inlight of constraints placed in recent years by the multimessenger astrophysicsof compact stars on the compact stars' masses, radii, and tidaldeformabilities. The effects of kaon condensation and strong magnetic fields onthe composition of hypernuclear stars are also discussed. The properties ofrapidly rotating compact hypernuclear stars are discussed and confronted withthe observations of 2.5-2.8 solar mass compact objects in gravitational waveevents. We further discuss the cooling of hypernuclear stars, the neutrinoemission reactions, hyperonic pairing, and the mass hierarchy in the coolingcurves that arises due to the onset of hyperons. The effects of hyperons and$\Delta$-resonances on the equation of state of hot nuclear matter in the denseregime, relevant for the transient astrophysical event and in the dilute regimerelevant to the collider physics is discussed. The review closes with adiscussion of universal relations among the integral parameters of hot and coldhypernuclear stars and their implications for the analysis of binary neutronstar merger events.

Lattice QCD calculations of two-nucleon interactions have been underway for about a decade, but still haven't reached the pion mass regime necessary for matching onto effective field theories and extrapolating to the physical point. Furthermore, results from different methods, including the use of the Lüscher formalism with different types of operators, as well as the HALQCD potential method, do not agree even qualitatively at very heavy pion mass. We investigate the role that different operators employed in the literature may play on the extraction of spectra for use within the Lüscher method. We first explore expectations from Effective Field Theory solved within a finite volume, for which the exact spectrum may be computed given different physical scenarios. We then present preliminary lattice QCD results for two-nucleon spectra calculated using different operators on a common lattice ensemble.

Recent observations of the angular correlation spectra in the decays $ {\rm^4He}^*\to {\rm ^4He}+ e^+e^-$ and $ {\rm ^8Be}^*\to {\rm ^8Be}+ e^+e^-$ havebeen suggested as due to the creation and subsequent decay to anelectron-positron pair of a new light particle with a mass of $\sim 17$ MeV. Inthis work, we present a calculation of the invariant $m_{e^+e^-}$ mass spectrumof the electromagnetic transition of an excited state of helium and estimatethe differential and total width of the decay. We investigate the possibilitythat the source of the signal is an $e^+ e^-$ pair created by a newelectromagnetic decay of $\rm ^4He$ caused by a proposed 12-quark hidden-colorFock state in the ${\rm {^4He}}$ nuclear wavefunction, the "hexadiquark.'' Wefind that we can fit the shape of the signal with the QCD Fock state atexcitation energy ${\rm E^*}\simeq 17.9 $ MeV and a Gaussian form factor forthe electromagnetic decay. We address the physical issues with the fitparameters using properties of the hexadiquark state. In light of this work, weemphasize the need for independent experimental confirmation or refutation ofthe ATOMKI results as well as further experiments to detect the proposed newexcitation of ${\rm ^4He}$.

Cumulants of baryon number are given considerable attention in analyses ofheavy-ion collision experiments as possible signatures of the QCD criticalpoint. In this work, we show that the values of the lowest three cumulants canalso be utilized to recover information about the isothermal speed of sound andits logarithmic derivative with respect to the baryon number density. Thisresult provides a new method for obtaining information about fundamentalproperties of nuclear matter studied in heavy-ion collisions, with consequencesfor both the search for the QCD critical point and neutron star studies. Whilethe approximations and the model comparison we considered apply to experimentsat low energies, the approach itself can be used at any collision energyprovided that measurements of cumulants of baryon number distribution as wellas their temperature dependence are available.

We report a systematic measurement of cumulants, Cn, for net-proton, proton, and antiproton multiplicity distributions, and correlation functions, κn, for proton and antiproton multiplicity distributions up to the fourth order in Au+Au collisions at sNN=7.7, 11.5, 14.5, 19.6, 27, 39, 54.4, 62.4, and 200 GeV. The Cn and κn are presented as a function of collision energy, centrality and kinematic acceptance in rapidity, y, and transverse momentum, pT. The data were taken during the first phase of the Beam Energy Scan (BES) program (2010-2017) at the BNL Relativistic Heavy Ion Collider (RHIC) facility. The measurements are carried out at midrapidity (|y|< 0.5) and transverse momentum 0.4

Using combined data from the Relativistic Heavy Ion and Large Hadron Colliders, we constrain the shear and bulk viscosities of quark-gluon plasma (QGP) at temperatures of ∼150-350  MeV. We use Bayesian inference to translate experimental and theoretical uncertainties into probabilistic constraints for the viscosities. With Bayesian model averaging we propagate an estimate of the model uncertainty generated by the transition from hydrodynamics to hadron transport in the plasma's final evolution stage, providing the most reliable phenomenological constraints to date on the QGP viscosities.

Abstract: Using Soft-Collinear Effective Theory, we develop the transverse-momentum-dependent factorization formalism for heavy flavor dijet production in polarized-proton-electron collisions. We consider heavy flavor mass corrections in the collinear-soft and jet functions, as well as the associated evolution equations. Using this formalism, we generate a prediction for the gluon Sivers asymmetry for charm and bottom dijet production at the future Electron-Ion Collider. Furthermore, we compare theoretical predictions with and without the inclusion of finite quark masses. We find that the heavy flavor mass effects can give sizable corrections to the predicted asymmetry.

We study the properties of the strongly coupled quark-gluon plasma with a multistage model of heavy-ion collisions that combines the TRENTo initial condition ansatz, free-streaming, viscous relativistic hydrodynamics, and a relativistic hadronic transport. A model-to-data comparison with Bayesian inference is performed, revisiting assumptions made in previous studies. The role of parameter priors is studied in light of their importance for the interpretation of results. We emphasize the use of closure tests to perform extensive validation of the analysis workflow before comparison with observations. Our study combines measurements from the Large Hadron Collider (LHC) and the Relativistic Heavy Ion Collider (RHIC), achieving a good simultaneous description of a wide range of hadronic observables from both colliders. The selected experimental data provide reasonable constraints on the shear and the bulk viscosities of the quark-gluon plasma at T≈ 150-250 MeV, but their constraining power degrades at higher temperatures, T 250 MeV. Furthermore, these viscosity constraints are found to depend significantly on how viscous corrections are handled in the transition from hydrodynamics to the hadronic transport. Several other model parameters, including the free-streaming time, show similar model sensitivity, while the initial condition parameters associated with the TRENTo ansatz are quite robust against variations of the particlization prescription. We also report on the sensitivity of individual observables to the various model parameters. Finally, Bayesian model selection is used to quantitatively compare the agreement with measurements for different sets of model assumptions, including different particlization models and different choices for which parameters are allowed to vary between RHIC and LHC energies.

Excited state contamination remains one of the most challenging sources ofsystematic uncertainty to control in lattice QCD calculations of nucleon matrixelements and form factors: early time separations are contaminated by excitedstates and late times suffer from an exponentially bad signal-to-noise problem.High-statistics calculations at large time separations $\gtrsim1$ fm arecommonly used to combat these issues. In this work, focusing on $g_A$, weexplore the alternative strategy of utilizing a large number of relativelylow-statistics calculations at short to medium time separations (0.2--1 fm),combined with a multi-state analysis. On an ensemble with a pion mass ofapproximately 310 MeV and a lattice spacing of approximately 0.09 fm, we findthis provides a more robust and economical method of quantifying andcontrolling the excited state systematic uncertainty. A quantitative separationof various types of excited states enables the identification of the transitionmatrix elements as the dominant contamination. The excited state contaminationof the Feynman-Hellmann correlation function is found to reduce to the 1% levelat approximately 1 fm while for the more standard three-point functions, thisdoes not occur until after 2 fm. Critical to our findings is the use of aglobal minimization, rather than fixing the spectrum from the two-pointfunctions and using them as input to the three-point analysis. We find that theground state parameters determined in such a global analysis are stable againstvariations in the excited state model, the number of excited states, and thetruncation of early-time or late-time numerical data.

We investigate the effect of soft gluon radiations on the azimuthal angle correlation between the total and relative momenta of two jets in inclusive and exclusive dijet processes. We show that the final state effect induces a sizable cos(2ϕ) anisotropy due to gluon emissions near the jet cones. The phenomenological consequences of this observation are discussed for various collider experiments, including diffractive processes in ultraperipheral pA and AA collisions, inclusive and diffractive dijet production at the EIC, and inclusive dijet in pp and AA collisions at the LHC.

We apply recent developments in large momentum effective theory (LaMET) to formulate a nonperturbative calculation of the single transverse-spin asymmetry from the so-called Sivers mechanism in terms of quasi-transverse-momentum-dependent quark distribution functions. When the spin asymmetry is defined as the ratio of the quark Sivers function over the spin-averaged distribution, it can be directly calculated in terms of the relevant quasidistributions with the soft functions and perturbative matching kernels canceling out. Apart from the general formula presented, we have verified the result in the small transverse distance limit at one-loop order, which reduces to a collinear expansion at the twist-three level.

Dihadron azimuthal correlations containing a high transverse momentum (pT) trigger particle are sensitive to the properties of the nuclear medium created at RHIC through the strong interactions occurring between the traversing parton and the medium, i.e. jet-quenching. Previous measurements revealed a strong modification to dihadron azimuthal correlations in Au+Au collisions with respect to p+p and d+Au collisions. The modification increases with the collision centrality, suggesting a path-length or energy density dependence to the jet-quenching effect. This paper reports STAR measurements of dihadron azimuthal correlations in mid-central (20%-60%) Au+Au collisions at GeV as a function of the trigger particle's azimuthal angle relative to the event plane, . The azimuthal correlation is studied as a function of both the trigger and associated particle . The subtractions of the combinatorial background and anisotropic flow, assuming Zero Yield At Minimum (ZYAM), are described. The correlation results are first discussed with subtraction of the even harmonic (elliptic and quadrangular) flow backgrounds. The away-side correlation is strongly modified, and the modification varies with , with a double-peak structure for out-of-plane trigger particles. The near-side ridge (long range pseudo-rapidity correlation) appears to drop with increasing while the jet-like component remains approximately constant. The correlation functions are further studied with the subtraction of odd harmonic triangular flow background arising from fluctuations. It is found that the triangular flow, while responsible for the majority of the amplitudes, is not sufficient to explain the -dependence of the ridge or the away-side double-peak structure. The dropping ridge with could be attributed to a -dependent elliptic anisotropy; however, the physics mechanism of the ridge remains an open question. Even with a -dependent elliptic flow, the away-side correlation structure is robust. These results, with extensive systematic studies of the dihadron correlations as a function of , trigger and associated particle , and the pseudo-rapidity range , should provide stringent inputs to help understand the underlying physics mechanisms of jet-medium interactions in high energy nuclear collisions.

Dihadron azimuthal correlations containing a high transverse momentum (pT) trigger particle are sensitive to the properties of the nuclear medium created at RHIC through the strong interactions occurring between the traversing parton and the medium, i.e. jet-quenching. Previous measurements revealed a strong modification to dihadron azimuthal correlations in Au+Au collisions with respect to p+p and d+Au collisions. The modification increases with the collision centrality, suggesting a path-length or energy density dependence to the jet-quenching effect. This paper reports STAR measurements of dihadron azimuthal correlations in mid-central (20%-60%) Au+Au collisions at GeV as a function of the trigger particle's azimuthal angle relative to the event plane, . The azimuthal correlation is studied as a function of both the trigger and associated particle . The subtractions of the combinatorial background and anisotropic flow, assuming Zero Yield At Minimum (ZYAM), are described. The correlation results are first discussed with subtraction of the even harmonic (elliptic and quadrangular) flow backgrounds. The away-side correlation is strongly modified, and the modification varies with , with a double-peak structure for out-of-plane trigger particles. The near-side ridge (long range pseudo-rapidity correlation) appears to drop with increasing while the jet-like component remains approximately constant. The correlation functions are further studied with the subtraction of odd harmonic triangular flow background arising from fluctuations. It is found that the triangular flow, while responsible for the majority of the amplitudes, is not sufficient to explain the -dependence of the ridge or the away-side double-peak structure. The dropping ridge with could be attributed to a -dependent elliptic anisotropy; however, the physics mechanism of the ridge remains an open question. Even with a -dependent elliptic flow, the away-side correlation structure is robust. These results, with extensive systematic studies of the dihadron correlations as a function of , trigger and associated particle , and the pseudo-rapidity range , should provide stringent inputs to help understand the underlying physics mechanisms of jet-medium interactions in high energy nuclear collisions.

We report on a subpercent scale determination using the omega baryon mass and gradient-flow methods. The calculations are performed on 22 ensembles of Nf=2+1+1 highly improved, rooted staggered sea-quark configurations generated by the MILC and CalLat Collaborations. The valence quark action used is Möbius domain wall fermions solved on these configurations after a gradient-flow smearing is applied with a flowtime of tgf=1 in lattice units. The ensembles span four lattice spacings in the range 0.06a0.15 fm, six pion masses in the range 130mπ400 MeV and multiple lattice volumes. On each ensemble, the gradient-flow scales t0/a2 and w0/a and the omega baryon mass amω are computed. The dimensionless product of these quantities is then extrapolated to the continuum and infinite volume limits and interpolated to the physical light, strange and charm quark mass point in the isospin limit, resulting in the determination of t0=0.1422(14) fm and w0=0.1709(11) fm with all sources of statistical and systematic uncertainty accounted for. The dominant uncertainty in both results is the stochastic uncertainty, though for t0 there are comparable continuum extrapolation uncertainties. For w0, there is a clear path for a few-per-mille uncertainty just through improved stochastic precision, as recently obtained by the Budapest-Marseille-Wuppertal Collaboration.

We apply perturbative QCD to investigate the near threshold heavy quarkoniumphotoproduction at large momentum transfer. From an explicit calculation, weshow that the conventional power counting method will be modified and the threequark Fock state with nonzero orbital angular momentum dominates the nearthreshold production. It carries a power behavior of $1/(-t)^5$ for thedifferential cross section. We further comment on the impact of our results onthe interpretation of the experiment measurement in terms of the gluonicgravitational form factors of the proton.

We reformulate the continuous space Schr\"odinger equation in terms of spinHamiltonians. For the kinetic energy operator, the critical conceptfacilitating the reduction in model complexity is the idea of positionencoding. Binary encoding of position produces a Heisenberg-like model andyields exponential improvement in space complexity when compared to classicalcomputing. Encoding with a binary reflected Gray code, and a Hamming distance 2Gray code yields the additional effect of reducing the spin model down to theXZ and transverse Ising model respectively. We also identify the bijectivemapping between diagonal unitaries and the Walsh series, producing the mappingof any real potential to a series of $k$-local Ising models through the fastWalsh transform. Finally, in a finite volume, we provide some numericalevidence to support the claim that the total time needed for adiabaticevolution is protected by the infrared cutoff of the system. As a result,initial state preparation from a free-field wavefunction to an interactingsystem is expected to exhibit polynomial time complexity with volume andconstant scaling with respect to lattice discretization for all encodings. Forthe Hamming distance 2 Gray code, the evolution starts with the transverseHamiltonian before introducing penalties such that the low lying spectrumreproduces the energy levels of the Laplacian. The adiabatic evolution of thepenalty Hamiltonian is therefore sensitive to the ultraviolet scale. It isexpected to exhibit polynomial time complexity with lattice discretization, orexponential time complexity with respect to the number of qubits given a fixedvolume.

We present a method that may allow an estimate of the value of the speed ofsound as well as its logarithmic derivative with respect to the baryon numberdensity in matter created in heavy-ion collisions. To this end, we utilizewell-known observables: cumulants of the baryon number distribution. Inanalyses aimed at uncovering the phase diagram of strongly interacting matter,cumulants gather considerable attention as their qualitative behaviour alongthe explored range of collision energies is expected to aid in detecting theQCD critical point. We show that the cumulants may also reveal the behavior ofthe speed of sound in the temperature and baryon chemical potential plane. Wedemonstrate the applicability of such estimates within two models of nuclearmatter, and explore what might be understood from known experimental data.

Background: A number of accelerator-based isotope production facilities utilize 100- to 200-MeV proton beams due to the high production rates enabled by high-intensity beam capabilities and the greater diversity of isotope production brought on by the long range of high-energy protons. However, nuclear reaction modeling at these energies can be challenging because of the interplay between different reaction modes and a lack of existing guiding cross-section data. Purpose: A Tri-lab collaboration has been formed among the Lawrence Berkeley, Los Alamos, and Brookhaven National Laboratories to address these complexities by characterizing charged-particle nuclear reactions relevant to the production of established and novel radioisotopes. Method: In the inaugural collaboration experiments, stacked-targets of niobium foils were irradiated at the Brookhaven Linac Isotope Producer (Ep=200MeV) and the Los Alamos Isotope Production Facility (Ep=100MeV) to measure Nb93(p,x) cross sections between 50 and 200 MeV. First measurements of the Nb93(p,4n)Mo90 beam monitor reaction beyond 100 MeV are reported in this work, as part of the broadest energy-spanning dataset for the reaction to date. Nb93(p,x) production cross sections are additionally reported for 22 other measured residual products. The measured cross-section results were compared with literature data as well as the default calculations of the nuclear model codes TALYS, CoH, EMPIRE, and ALICE. Results: The default code predictions largely failed to reproduce the measurements, with consistent underestimation of the preequilibrium emission. Therefore, we developed a standardized procedure that determines the reaction model parameters that best reproduce the most prominent reaction channels in a physically justifiable manner. The primary focus of the procedure was to determine the best parametrization for the preequilibrium two-component exciton model via a comparison to the energy-dependent Nb93(p,x) data, as well as previously published La139(p,x) cross sections. Conclusions: This modeling study revealed a trend toward a relative decrease for internal transition rates at intermediate proton energies (Ep=20-60 MeV) in the current exciton model as compared to the default values. The results of this work are instrumental for the planning, execution, and analysis essential to isotope production.

Spectroscopic factors to low-lying negative-parity states in Be11 extracted from the B12(d,He3)Be11 proton-removal reaction are interpreted within the rotational model. Earlier predictions of the p-wave proton-removal strengths in the strong-coupling limit of the Nilsson model underestimated the spectroscopic factors to the 3/21- and 5/21- states and suggested that deviations in the 1+ ground state of the odd-odd B12 due to Coriolis coupling should be further explored. In this work we use the particle rotor model to take into account these effects and obtain a good description of the level scheme in B11, with a moderate K mixing of the proton Nilsson levels [110]1/2 and [101]3/2. This mixing, present in the 1+ bandhead of B12, is key to explaining the proton-pickup data.

The E12-14-012 experiment, performed in Jefferson Lab Hall A, has collected exclusive electron-scattering data (e,e′p) in parallel kinematics using natural argon and natural titanium targets. Here we report the first results of the analysis of the data set corresponding to beam energy 2222 GeV, electron scattering angle 21.5∘, and proton emission angle -50∘. The differential cross sections, measured with ≈4% uncertainty, have been studied as a function of missing energy and missing momentum, and compared to the results of Monte Carlo simulations, obtained from a model based on the distorted-wave impulse approximation.

The proposed electron-ion collider has a rich physics program to study theinternal structure of protons and heavy nuclei. This program will impose strictrequirements on detector design. This paper explores how these requirements canbe satisfied using an all-silicon tracking detector, by consideration of threerepresentative probes: heavy flavor hadrons, jets, and exclusive vector mesons.

We calculate neutron multiplicities from fission fragments with specified mass numbers for events having a specified total fragment kinetic energy. The shape evolution from the initial compound nucleus to the scission configurations is obtained with the metropolis walk method on the five-dimensional potential-energy landscape, calculated with the macroscopic-microscopic method for the three-quadratic-surface shape family. Shape-dependent microscopic level densities are used to guide the random walk, to partition the intrinsic excitation energy between the two proto-fragments at scission, and to determine the number of neutrons evaporated from the fragments. The contribution to the total excitation energy of the resulting fragments from statistical excitation and shape distortion at scission is studied. Good agreement is obtained with available experimental data on neutron multiplicities in correlation with fission fragments from U235(nth,f). With increasing neutron energy a superlong fission mode grows increasingly prominent, which affects the dependence of the observables on the total fragment kinetic energy.

The observed inclusive jet suppression in heavy-ion collisions at LHC has a very weak pT dependence over a large range of pT=50–1000GeV and is almost independent of the colliding energy, though the initial energy density of the bulk medium has increased from s=2.76 to 5.02TeV by about 20%. This interesting phenomenon is investigated in the linear Boltzmann transport (LBT) model for jet propagation in an event-by-event 3+1D hydro background. We show that the pT dependence of jet RAA is determined by the initial spectrum in p+p collisions and pT dependence of jet energy loss. Furthermore, jet energy loss distributions for inclusive jet and γ-jet at both LHC energies are extracted directly from experimental data through the state-of-art Bayesian analysis. The averaged jet energy loss has a weak pT dependence and the scaled jet energy loss distributions have a large width, both of which are consistent with the LBT simulations and indicate that jet quenching is caused by only a few out-of-cone jet medium scatterings.

We report on the first application of the stochastic Laplacian Heaviside method for computing multiparticle interactions with lattice QCD to the two-nucleon system. Like the Laplacian Heaviside method, this method allows for the construction of interpolating operators which can be used to construct a set of positive-definite two-nucleon correlation functions, unlike nearly all other applications of lattice QCD to two nucleons in the literature. It also allows for a variational analysis in which optimal linear combinations of the interpolating operators are formed that couple predominantly to the eigenstates of the system. Utilizing such methods has become of paramount importance to help resolve the discrepancy in the literature on whether two nucleons in either isospin channel form a bound state at pion masses heavier than physical, with the discrepancy persisting even in the SU(3)-flavor-symmetric point with all quark masses near the physical strange quark mass. This is the first in a series of papers aimed at resolving this discrepancy. In the present work, we employ the stochastic Laplacian Heaviside method without a hexaquark operator in the basis at a lattice spacing of a≈0.086 fm, lattice volume of L=48a≈4.1 fm and pion mass mπ≈714 MeV. With this setup, the observed spectrum of two-nucleon energy levels strongly disfavors the presence of a bound state in either the deuteron or dineutron channel.

Using the CUJET3=DGLV+VISHNU jet-medium interaction framework, we show that dijet azimuthal acoplanarity in high energy A + A collisions is sensitive to possible non-perturbative enhancement of the jet transport coefficient, qˆ(T,E), in the QCD crossover temperature T ∼ 150–300 MeV range. With jet-medium couplings constrained by global RHIC& LHC χ2 fits to nuclear modification data on RAA(pT > 20) GeV, we compare predictions of the medium induced dijet transverse momentum squared, Qs2∼〈qˆL〉∼Δϕ2E2, in two models of the temperature, T, and jet energy E dependence of the jet medium transport coefficient, qˆ(T,E)). In one model, wQGP, the chromo degrees of freedom (dof) are approximated by a perturbative dielectric gas of quark and gluons dof. In the second model, sQGMP, we consider a nonperturbative partially confined semi-Quark-Gluon-Monopole-Plasma with emergent color magnetic dof constrained by lattice QCD data. Unlike the slow variation of the scaled jet transport coefficient, qˆwQGP/T3, the sQGMP model qˆsQGMP/T3 features a sharp maximum in the QCD confinement crossover T range. We show that the dijet path averaged medium induced azimuthal acoplanarity, Δϕ2, in sQGMP is robustly ∼ 2 times larger than in perturbative wQGP. even though the radiative energy loss in both models is very similar as needed to fit the same RAA data. Future A+A dijet acoplanarity measurements constrained together with single jet RAA and νn measurements therefore appears to be a promising strategy to search for possible signatures of critical opalescence like phenomena in the QCD confinement temperature range.

The preliminary STAR data for proton cumulants for central collisions at s=7.7GeV component proton multiplicity distribution. We show that this two-component distribution is statistics friendly in that factorial cumulants of surprisingly high orders may be extracted with a relatively small number of events. As a consequence the two-component model can be tested and verified right now with the presently available STAR data from the first phase of the RHIC beam energy scan.

We report on the first application of the stochastic Laplacian Heaviside method for computing multiparticle interactions with lattice QCD to the two-nucleon system. Like the Laplacian Heaviside method, this method allows for the construction of interpolating operators which can be used to construct a set of positive-definite two-nucleon correlation functions, unlike nearly all other applications of lattice QCD to two nucleons in the literature. It also allows for a variational analysis in which optimal linear combinations of the interpolating operators are formed that couple predominantly to the eigenstates of the system. Utilizing such methods has become of paramount importance to help resolve the discrepancy in the literature on whether two nucleons in either isospin channel form a bound state at pion masses heavier than physical, with the discrepancy persisting even in the SU(3)-flavor-symmetric point with all quark masses near the physical strange quark mass. This is the first in a series of papers aimed at resolving this discrepancy. In the present work, we employ the stochastic Laplacian Heaviside method without a hexaquark operator in the basis at a lattice spacing of a≈0.086 fm, lattice volume of L=48a≈4.1 fm and pion mass mπ≈714 MeV. With this setup, the observed spectrum of two-nucleon energy levels strongly disfavors the presence of a bound state in either the deuteron or dineutron channel.

The preliminary STAR data for proton cumulants for central collisions at s=7.7GeV component proton multiplicity distribution. We show that this two-component distribution is statistics friendly in that factorial cumulants of surprisingly high orders may be extracted with a relatively small number of events. As a consequence the two-component model can be tested and verified right now with the presently available STAR data from the first phase of the RHIC beam energy scan.

We present an implementation of an explainable and physics-aware machinelearning model capable of inferring the underlying physics of high-energyparticle collisions using the information encoded in the energy-momentumfour-vectors of the final state particles. We demonstrate the proof-of-conceptof our White Box AI approach using a Generative Adversarial Network (GAN) whichlearns from a DGLAP-based parton shower Monte Carlo event generator. We show,for the first time, that our approach leads to a network that is able to learnnot only the final distribution of particles, but also the underlying partonbranching mechanism, i.e. the Altarelli-Parisi splitting function, the orderingvariable of the shower, and the scaling behavior. While the current work isfocused on perturbative physics of the parton shower, we foresee a broad rangeof applications of our framework to areas that are currently difficult toaddress from first principles in QCD. Examples include nonperturbative andcollective effects, factorization breaking and the modification of the partonshower in heavy-ion, and electron-nucleus collisions.

We investigate the azimuthal angular correlation between the lepton transverse momentum P_{⊥} and the impact parameter b_{⊥} in noncentral heavy-ion collisions, where the leptons are produced through two-photon scattering. Among the Fourier harmonic coefficients, a significant v_{4} asymmetry is found for the typical kinematics at RHIC and LHC with a mild dependence on the P_{⊥}, whereas v_{2} is power suppressed by the lepton mass over P_{⊥}. This unique prediction, if confirmed from the experiments, shall provide crucial information on the production mechanism for the dilepton in two-photon processes.

We review the present status of the Standard Model calculation of the anomalous magnetic moment of the muon. This is performed in a perturbative expansion in the fine-structure constant α and is broken down into pure QED, electroweak, and hadronic contributions. The pure QED contribution is by far the largest and has been evaluated up to and including O(α5) with negligible numerical uncertainty. The electroweak contribution is suppressed by (mμ∕MW)2 and only shows up at the level of the seventh significant digit. It has been evaluated up to two loops and is known to better than one percent. Hadronic contributions are the most difficult to calculate and are responsible for almost all of the theoretical uncertainty. The leading hadronic contribution appears at O(α2) and is due to hadronic vacuum polarization, whereas at O(α3) the hadronic light-by-light scattering contribution appears. Given the low characteristic scale of this observable, these contributions have to be calculated with nonperturbative methods, in particular, dispersion relations and the lattice approach to QCD. The largest part of this review is dedicated to a detailed account of recent efforts to improve the calculation of these two contributions with either a data-driven, dispersive approach, or a first-principle, lattice-QCD approach. The final result reads aμSM=116591810(43)×10−11 and is smaller than the Brookhaven measurement by 3.7σ. The experimental uncertainty will soon be reduced by up to a factor four by the new experiment currently running at Fermilab, and also by the future J-PARC experiment. This and the prospects to further reduce the theoretical uncertainty in the near future – which are also discussed here – make this quantity one of the most promising places to look for evidence of new physics.

This paper investigates the electromagnetic production of lepton pairs with low total transverse momentum in relativistic heavy-ion collisions. We estimate the initial photons' transverse momentum contributions by employing models where the average transverse momentum squared of the incoming photon can be calculated in the equivalent photon approximation. We further derive an all order QED resummation for the soft photon radiation, which gives an excellent description of the ATLAS data in ultraperipheral collisions at the LHC. For peripheral and central collisions, additional pT-broadening effects from multiple interactions with the medium and the magnetic field contributions from the quark-gluon plasma are also discussed.

The JETSCAPE framework is a modular and versatile Monte Carlo software package for the simulation of high energy nuclear collisions. In this work we present a new tune of JETSCAPE, called PP19, and validate it by comparison to jet-based measurements in p+p collisions, including inclusive single jet cross sections, jet shape observables, fragmentation functions, charged hadron cross sections, and dijet mass cross sections. These observables in p+p collisions provide the baseline for their counterparts in nuclear collisions. Quantifying the level of agreement of JETSCAPE results with p+p data is thus necessary for meaningful applications of JETSCAPE to A+A collisions. The calculations use the JETSCAPE PP19 tune, defined in this paper, based on version 1.0 of the JETSCAPE framework. For the observables discussed in this work calculations using JETSCAPE PP19 agree with data over a wide range of collision energies at a level comparable to standard Monte Carlo codes. These results demonstrate the physics capabilities of the JETSCAPE framework and provide benchmarks for JETSCAPE users.

The transversely-polarized state of a proton with arbitrary momentum is not an eigenstate of transverse angular momentum operator. The latter does not commute with the QCD Hamiltonian. However, the expectation value of the transverse angular momentum in the state is well-defined and grows proportionally to the energy of the particle. The transverse spin content of the proton is analyzed in terms of the QCD angular momentum structure. In particular, we reconfirm that the generalized parton distributions H+E provide the leading-twist transverse angular momentum densities of quarks and gluons in the infinite momentum frame.

The transversely-polarized state of a proton with arbitrary momentum is not an eigenstate of transverse angular momentum operator. The latter does not commute with the QCD Hamiltonian. However, the expectation value of the transverse angular momentum in the state is well-defined and grows proportionally to the energy of the particle. The transverse spin content of the proton is analyzed in terms of the QCD angular momentum structure. In particular, we reconfirm that the generalized parton distributions H+E provide the leading-twist transverse angular momentum densities of quarks and gluons in the infinite momentum frame.

This report summarizes the presentations and discussions during the Rapid Reaction Task Force “Dynamics of critical fluctuations: Theory – phenomenology – heavy-ion collisions”, which was organized by the ExtreMe Matter Institute EMMI and held at GSI, Darmstadt, Germany in April 2019. We address the current understanding of the dynamics of critical fluctuations in QCD and their measurement in heavy-ion collision experiments. In addition, we outline what might be learned from studying correlations in other physical systems, such as cold atomic gases.

This report summarizes the presentations and discussions during the Rapid Reaction Task Force “Dynamics of critical fluctuations: Theory – phenomenology – heavy-ion collisions”, which was organized by the ExtreMe Matter Institute EMMI and held at GSI, Darmstadt, Germany in April 2019. We address the current understanding of the dynamics of critical fluctuations in QCD and their measurement in heavy-ion collision experiments. In addition, we outline what might be learned from studying correlations in other physical systems, such as cold atomic gases.

We present a framework to simulate the dynamics of hard probes such as heavyquarks or jets in a hot, strongly-coupled quark-gluon plasma (QGP) on a quantumcomputer. Hard probes in the QGP can be treated as open quantum systemsgoverned in the Markovian limit by the Lindblad equation. However, due to largecomputational costs, most current phenomenological calculations of hard probesevolving in the QGP use semiclassical approximations of the quantum evolution.Quantum computation can mitigate these costs, and offers the potential for afully quantum treatment with exponential speedup over classical techniques. Wereport a simplified demonstration of our framework on IBM Q quantum devices,and apply the Random Identity Insertion Method (RIIM) to account for CNOTdepolarization noise, in addition to measurement error mitigation. Our workdemonstrates the feasibility of simulating open quantum systems on current andnear-term quantum devices, which is of broad relevance to applications innuclear physics, quantum information, and other fields.

In a recent experiment, carried out at the Radioactive Isotope Beam Factory/RIKEN, the F25(p,2p)O24 reaction was studied at 270 MeV/A in inverse kinematics. Derived spectroscopic factors suggest that the effective core of F25 significantly differs from a free O24 nucleus. We interpret these results within the particle-rotor model and show that the experimental level scheme of F25 can be understood in the rotation-aligned coupling scheme with its 5/21+ ground state as the bandhead of a decoupled band. The excitation energies of the observed 1/21+ and 9/21+ states correlate strongly with the rotational energy of the effective core, seen by the odd proton, and allow us to estimate its 2+ energy at ≈3.2MeV and a moderate quadrupole deformation ϵ2≈0.15. The measured fragmentation of the πd5/2 single-particle strength is discussed, and some further experiments suggested.

We report here the results of a measurement of the scattered versus unscattered neutron fluence on polyethylene determined via neutron activation of multiple natural indium foils from a deuterium-deuterium (D-D) neutron generator. The neutrons were produced by the High Flux Neutron Generator (HFNG) at the University of California, Berkeley, a specially designed source to maximize neutron flux on a sample while minimizing the total neutron yield. During the experiment, approximately 108 n/s were produced with the energies at the indium foils ranging from 2.2 to 2.8 MeV. Both the angle-integrated and the partial angle differential results are consistent with the predictions of the Monte Carlo N-Particle Transport (MCNP) code, using ENDF/B-VII.1. This supports shielding calculations in the fast energy region with high-density polyethylene.

In a recent experiment, carried out at the Radioactive Isotope Beam Factory/RIKEN, the F25(p,2p)O24 reaction was studied at 270 MeV/A in inverse kinematics. Derived spectroscopic factors suggest that the effective core of F25 significantly differs from a free O24 nucleus. We interpret these results within the particle-rotor model and show that the experimental level scheme of F25 can be understood in the rotation-aligned coupling scheme with its 5/21+ ground state as the bandhead of a decoupled band. The excitation energies of the observed 1/21+ and 9/21+ states correlate strongly with the rotational energy of the effective core, seen by the odd proton, and allow us to estimate its 2+ energy at ≈3.2MeV and a moderate quadrupole deformation ϵ2≈0.15. The measured fragmentation of the πd5/2 single-particle strength is discussed, and some further experiments suggested.

The PRad experiment has credibly demonstrated the advantages of thecalorimetric method in e-p scattering experiments to measure the protonroot-mean-square (RMS) charge radius with high accuracy. The PRad result,within its experimental uncertainties, is in agreement with the small radiusmeasured in muonic hydrogen spectroscopy experiments and it was a criticalinput in the recent revision of the CODATA recommendation for the proton chargeradius. Consequently, the PRad result is in direct conflict with all modernelectron scattering experiments. Most importantly, it is 5.8% smaller than thevalue from the most precise electron scattering experiment to date, and thisdifference is about three standard deviations given the precision of the PRadexperiment. As the first experiment of its kind, PRad did not reach the highestprecision allowed by the calorimetric technique. Here we propose a new (and)upgraded experiment -- PRad-II, which will reduce the overall experimentaluncertainties by a factor of 3.8 compared to PRad and address this as yetunsettled controversy in subatomic physics. In addition, PRad-II will be thefirst lepton scattering experiment to reach the Q^2 range of 10^{-5} GeV^2allowing a more accurate and robust extraction of the proton charge radius. Themuonic hydrogen result with its unprecedented precision (~0.05%) determines theCODATA value of the proton charge radius, hence, it is critical to evaluatepossible systematic uncertainties of those experiments, such as the laserfrequency calibration that was raised in recent review articles. The PRad-IIexperiment with its projected total uncertainty of 0.43% could demonstratewhether there is any systematic difference between $e-p$ scattering and muonichydrogen results. PRad-II will establish a new precision frontier in electronscattering and open doors for future physics opportunities.

We investigate the effect of PT-broadening on jet substructure observables in heavy-ion collisions at the LHC. As an example, we focus on the opening angle of the two branches that satisfy the soft drop grooming condition in a highly energetic jet. The medium modification of the angular distribution can provide important information on the jet transport properties of hot QCD matter. In addition, we take into account a change of the overall fraction of quark and gluon jets in heavy-ion collisions. We comment on the comparison to a recent measurement from the ALICE Collaboration.