Papers

The $\Lambda p$ invariant-mass spectrum near the two physical $\Sigma N$ thresholds in the $K^-d\to\pi^-\Lambda p$ reaction is studied as a probe of the low-energy $\Sigma N$ interaction. The reaction is formulated up to two-step processes, and the coupled $\Lambda p$, $\Sigma^+n$, and $\Sigma^0p$ channels are described within a constant-$K$-matrix model constrained by spin-triplet scattering lengths. The dependence of the $\Sigma N\to\Lambda p$ conversion amplitude on these scattering lengths is examined, and the relation between its line shape and nearby pole positions is investigated. The resulting invariant-mass spectra are studied at different incident kaon momenta and compared qualitatively with existing experimental data. The effects of the spin-singlet $YN$ amplitude and the deuteron wave function are also examined. The line shape near the $\Sigma N$ thresholds is found to be particularly sensitive to the complex spin-triplet $I=1/2$ $\Sigma N$ scattering length, indicating that measurements of this spectrum can provide useful constraints on the low-energy $\Sigma N$ interaction.

Precision measurements of nuclear $\beta$ decay offer a powerful route to tests of physics beyond the Standard Model, but interpreting measurements spectra and correlation observables requires control of subtle nuclear-structure effects. This chapter develops a framework for calculating higher-order corrections–small contributions that can become important at the precision sought in searches for new interactions. After motivating their role in $\beta$-decay observables (with radiative corrections treated in the accompanying chapter), we introduce the relevant kinematics and multipole expansion of the shape factor, identify the subleading contributions, and present the impulse-approximation multipole operators. We then describe the nuclear many-body methods used to obtain the required states and transition densities, and derive the corresponding operator matrix elements in the harmonic-oscillator basis. Taken together, these ingredients enable systematic calculations of nuclear shape factors beyond the long-wavelength approximation, including higher-order multipoles where needed. By helping distinguish Standard-Model recoil effects from possible signatures of new physics, this framework supports the interpretation of increasingly precise $\beta$-decay experiments.

Quantum computation offers a promising alternative to classical Monte Carlo methods by naturally avoiding sign problems through unitary evolution. A common misconception follows from this: because quantum simulation sidesteps the sign problem, it is often assumed to be an essentially perfect substitute for classical sampling. This is false—quantum measurements are intrinsically stochastic, and estimating observables often requires a number of samples that grows exponentially with system size, time separation, or inverse temperature, exactly as in the classical signal-to-noise problem. In this work, we analyze the origin and structure of signal-to-noise problems in quantum computation, drawing parallels with classical Monte Carlo, and demonstrate that such noise persists even in sign-problem-free regimes. We discuss strategies to mitigate it, in particular a quantum generalization of Stein control variates construction, in which unbiased estimators are built from operator commutators $[X,A]$ and their discrete diagonal counterparts, and validate the approach with exactly solvable numerical examples that quantify the achievable variance reduction. Our results underscore that variance reduction, not merely sign-problem avoidance, is required to make quantum algorithms practically viable for many-body physics.

At sufficiently high temperatures, lattice Quantum Chromodynamics (QCD) calculations predict that nuclear matter undergoes a rapid crossover to a novel, deconfined state known as the quark-gluon plasma (QGP), in which quark flavors essentially behave like independent particles. Here we explore the nature of this transition by introducing two new thermodynamic observables which we refer to as the diagonality and the rescaled curvature of the QCD equation of state (EoS). By comparing these observables in the case of lattice QCD calculations with those of simple toy models and more sophisticated hadronic resonance models, we show that both the diagonality and the rescaled curvature provide complementary insights into the degree of independence between different quark flavors and the underlying degrees of freedom in the system as functions of temperature. We propose that these observables may help to clarify the nature of the transition region and the onset of deconfinement in nuclear matter.

We investigate how femtoscopic correlations modify the relation between the spin entanglement of emitted particle pairs and that of pairs selected at a given relative momentum. For two spin-$\frac{1}{2}$ particles, we show that the momentum-selected spin state can be entangled even when the corresponding state at emission is separable. We derive a momentum-dependent separability criterion that determines whether the observed spin correlations require entanglement at emission. As an application, we consider a pair of identical $\Lambda$ hyperons, for which quantum statistics and final-state interactions affect the singlet and triplet spin channels differently at low relative momentum. Our results provide a framework for using experimentally accessible spin correlations to investigate entanglement at emission.

We introduce the ratio of electron capture to positron decay rates of unstable nuclei as a probe for exotic tensor currents in the electroweak sector. We calculate nuclear structure corrections and newly derived radiative corrections and obtain competitive limits on exotic tensor couplings using historically available data to find $\varepsilon_T = (1.06 \pm 0.76)\times 10^{-3}$ which is competitive with collider searches and the global $\beta$-decay database. In doing so, we resolve a 50-year-old tension in the strongly hindered $^{22}$Na transition by retaining higher-order operators, obtaining a consistent description of its different weak-decay observables. Finally, we discuss the potential of this method to significantly improve tensor constraints using modern cryogenic quantum sensors.

Shuang-Jie Liu et al. (arXiv:2604.27678) reported that the momentum-dependent nuclear mean field (MDI) with $K_0 = 230$ MeV 'can fit fairly' the experimental data for Au + Au collisions at $\sqrt{s_{NN}} = 3$ GeV, whereas the momentum-independent nuclear mean fields (MID) with $K_0 = 230$ MeV and $K_0 = 380$ MeV 'can only partially describe' the experimental results. We quantify these statements by performing $\chi^2$ goodness-of-fit tests for the comparison between the theoretical calculations and the experimental distributions presented in that work. For the complete set of data, all three calculations show highly statistically significant disagreement with the experimental data, with (p-value) p < 0.001. For the $0-10\%$ centrality class, however, the MDI calculation with $K_0 = 230$ MeV gives p = 0.49, indicating no statistically significant disagreement with the experimental data for the proton transverse-momentum distributions and the rapidity dependence of the mean transverse momentum, whereas both MID calculations give p < 0.001. For the $10-40\%$ centrality class, the analysis of the directed flows of protons, $K^+$ mesons, and $\Lambda$-hyperons gives the largest p-values for MDI with $K_0 = 230$ MeV and MID with $K_0 = 380$ MeV, with p = 1.00 and p = 0.97, respectively. In contrast, the analysis of the corresponding elliptic flow data gives p < 0.001 for all three calculations. Our results demonstrate that the qualitative statements 'fit fairly' and 'only partially describe' depend substantially on the particular observables and centrality classes considered and cannot by themselves establish statistically acceptable agreement between the calculations and the experimental data.

In this paper we compute several structural properties of static and rotating neutron stars, considering both rigid and differential rotation. To this end, we use a finite-temperature beta-stable equation of state (EOS) extending the zero-temperature hadronic EOS derived by Fortin et al. (2017). We account for the formation of hyperons and the presence of a neutrino-trapped component. Our goal is to provide insights into the long-term evolution of a protoneutron star (PNS) formed after a core-collapse supernova (CCSN) or a remnant resulting from a binary neutron star merger (BNSM). The EOS is derived using a relativistic mean-field quantum many-body theory within the Hartree approximation. Coupling constants are determined using experimental data on hypernuclei and hypernuclear matter to better account for uncertainties in hyperon single-particle potentials. Our EOS models reproduce the typical features of cold neutron stars and PNSs for nucleonic and hyperonic compositions. In particular, they are consistent with measured masses (2.01 M_sun and 2.14 M_sun for PSR J0348+0432 and PSR J0740+6620) and dimensionless tidal deformabilities from GW170817. Thermal contributions act differently depending on composition and rotation state. Finally, our evolutionary scheme provides a simple way to interpret the long-term evolution of BNSM remnants or PNSs from CCSNe, complementing dynamical simulations unable to cover full evolutionary timescales.

Nucleosynthesis simulations of the r-process require neutron capture rates for neutron-rich nuclei, many of which lie beyond experimental reach. Predicting these rates relies on theoretical calculations of the low-energy electric dipole (E1) strength near the neutron threshold. We present the first ab initio computation of the E1 strength along the nickel isotopic chain, for $^{58}$Ni and the even-even isotopes $^{68-80}$Ni. The E1 strength is obtained with the Lorentz integral transform coupled-cluster (LIT-CC) method, extended to axially symmetric reference states to reach open-shell nuclei, using two- and three-nucleon interactions from chiral effective field theory. The approach is benchmarked against the measured photoabsorption cross section of $^{58}$Ni and the E1 strength of $^{68}$Ni. Along the chain we find low-lying E1 strength above the neutron threshold that grows with neutron number. Including it in the reaction code TALYS enhances the neutron capture rates forming $^{68-78}$Ni between 3 and 10 GK, with an effect that increases with temperature and neutron number and an uncertainty dominated by the inversion of the integral transform. For $^{80}$Ni, where strong pygmy dipole strength lies just above threshold, the enhancement sets in already around 0.5 GK. Together, these results open the way to ab initio input for neutron capture rates along isotopic chains far from stability.

Experiments in relativistic heavy-ion collisions determine centrality from final-state quantities, usually the charged-particle multiplicity. Performing the same in hydrodynamic simulations requires millions of events, which is impractical for state-of-the-art hybrid models, and centrality is therefore commonly approximated by the initial entropy or energy. We show that neural networks trained on a few hundred hybrid events predict the event-by-event multiplicity and mean transverse momentum $[p_T]$ with relative errors of 1–2%, which makes it possible to generate millions of collisions at a small fraction of the cost of the full simulation. For Pb–Pb collisions at $2.76$~TeV and Au–Au collisions at $200$~GeV, the initial-state and final-state definitions select nearly the same events in 10%-wide classes, but up to 20% of the events change class when the classes are 1% wide. We then compute the fluctuations of $[p_T]$ and its Pearson correlations with a proxy of the elliptic flow, estimated from the initial eccentricity, and with multiplicity. The first correlation is insensitive to how centrality is defined, while the second changes substantially. The approach can be applied at every design point of Bayesian analyses at modest additional cost.

We investigate the anomaly-induced transport properties of a holographic superconductor exhibiting spontaneous symmetry breaking. The holographic model incorporates vector and axial gauge fields, an additional non-anomalous $U(1)$ symmetry, and a charged scalar field that drives the phase transition. Working in the probe limit, we numerically construct the superconducting background under two alternative scalar field quantizations, corresponding to operators with scaling dimensions $\Delta=1$ and $\Delta=3$ (denoted as the $O_1$ and $O_2$ theories, respectively). Using Kubo formulae, we compute the chiral magnetic conductivities and examine their response to the scalar condensate. Our findings demonstrate that spontaneous symmetry breaking allows anomaly-induced transport to extend beyond anomalous currents, significantly impacting the non-anomalous sector as well. Remarkably, this effect appears in both theories, indicating that the influence on the non-anomalous sector is independent of the chosen quantization. The comparison of our numerical results with the analytical limits for $O_i \to 0$ and $O_i \to \infty$ $(i=1,2)$ reveals consistent behavior across both theories.

We present the new release of nuclear parton distribution functions (nPDFs) from the nCTEQ collaboration: nCTEQ26. In this global analysis, we combine our recent, more selective studies of different experimental measurements and extend them to determine a modern set of nPDFs based on the largest selection of data considered to date. This selection includes neutral- and charged-current deep-inelastic scattering (DIS), fixed-target Drell-Yan, and a large variety of collider data from RHIC and LHC Runs I and II. On the theoretical side, we match this considerably extended kinematic range with a new nPDF parametrization that combines a flexible functional form of the x-dependence with a quadratic logarithmic nuclear A-dependence as well as target-mass and deuteron corrections for the reliable inclusion of high-x DIS data. Following our previous successful work, we partially employ a data-driven approach that allows us to not only include open heavy-quark data, but also quarkonium data. In addition, we establish the consistency of this approach by comparing it to an alternative fit based on perturbative predictions of open heavy-quark data alone. We determine the uncertainties of our nCTEQ26 nPDFs with a Hessian error analysis, test their reliability by comparing our nPDFs to other, similar recent analyses, and make predictions for current and future experimental measurements that have not been included in the analysis.

Many deformed nuclei exhibit low-lying rotational bands with negative parity. In mean-field calculations, such bands follow from symmetry restoration when the variational solution spontaneously breaks parity. However, they can also be computed in cases where the breaking of parity is not spontaneous but rather enforced by an octupole constraint. In this paper, we extend these techniques to coupled-cluster computations. We introduce octupole-constrained coupled-cluster theory, which explicitly breaks the parity of the correlated intrinsic state and restores parity and angular momentum as good quantum numbers by projection after variation. We perform coupled-cluster singles-and-doubles (CCSD) computations for $^{20}$Ne using two- and three-nucleon forces from chiral effective field theory. The energies of the positive-parity ground-state rotational band are close to data and depend only weakly on the constrained octupole moment and the Hartree–Fock reference. In contrast, the energies of the negative-parity rotational band are more sensitive to these auxiliary quantities.

An important goal of high-energy physics is to better understand the spacetime structure of particle emitting sources created in heavy-ion collisions. For a fraction of a second a special form of matter, the so-called quark-gluon plasma (QGP) is created, which can be examined with the toolkit of femtoscopy. With the measurement of correlation functions it was determined that Lévy distributions describe the shape of QGP sources the most accurately, however, based on hydrodynamics Gaussian distributions are typically expected. In this article we showcase an exact solution of the equations of relativistic hydrodynamics, which aims to resolve this puzzle by providing Lévy distributions directly from hydrodynamics. A detailed analysis reveals whether the predictions of this solution are in accordance with observations.

Impacts of octupole correlations on low-energy excited $0^+$ states and two-neutron transfer intensities in Ra and Th isotopes are analyzed within the interacting boson model, using the Hamiltonian parameters that are obtained from microscopic nuclear density functional theory calculations. Incorporating the octupole degree of freedom in the model is shown to give an overall reasonable description of the ground-state-band energy levels and to lower the $0^+_2$ ones significantly. The calculation yields a number of excited $0^+$ states, most of which are formed by the configurations of more than one octupole boson. Octupole correlations make significant contributions to the $0^+_1 \to 0^+_2$ $(p,t)$ and $(t,p)$ transfer intensities in those nuclei in which the octupole collectivity is most enhanced. Behaviors of the predicted transfer intensities with the increasing neutron number along the isotopic chain reflect nuclear structural evolution.

Energetic partons traversing the quark-gluon plasma in relativistic heavy-ion collisions induce a medium response that modifies the production of associated hadrons, whose chemical composition provides a sensitive probe of this response. We study jet-associated hadrochemistry using the coupled linear Boltzmann transport and hydrodynamics model with a hybrid hadronization scheme that combines Cooper–Frye particlization, quark coalescence and string fragmentation. For inclusive charged jets in $p+p$ and 0–10% central Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$~TeV, the calculated in-cone $K/\pi$ and $p/\pi$ ratios are enhanced in Pb+Pb relative to $p+p$ collisions, consistent with preliminary ALICE measurements, with coalescence between shower and thermal partons providing a substantial contribution. Extending the analysis to dijet events, we predict that both ratios are enhanced around the leading and subleading jets, more strongly around the subleading jet and more pronounced for larger radial size. After mixed-event acceptance correction and sideband background subtraction, the yields of associated pions, kaons and protons all become negative near $|\Delta\phi|\simeq\pi/2$, signaling a depletion caused by the diffusion wake. The $K/\pi$ and $p/\pi$ ratios of these deficits remain finite and exceed the $p+p$ values around the jet peaks, indicating that the missing hadrons originate from jet-excited medium. These results establish dijet hadrochemistry as an experimentally accessible tomographic probe of jet-induced medium excitation and the diffusion wake.

A macroscopic method of the parton and hadron cascade model PACIAE combined with the coalescence model DCPC is employed to study the $\phi$-mesic nuclei in $pp$ collisions at $\sqrt{s}$ = 7 TeV for the first time in this work. Based on the final hadronic states of $pp$ collisions simulated by the PACIAE model, the $\phi$-mesic nuclei: $\mathrm{^3_{\phi} H}(\phi-pn)$, $\mathrm{^4_{\phi} H}(\phi-pnn)$, and $\mathrm{^4_{\phi} He}(\phi-ppn)$ are recombined by the DCPC model with constituents of protons, neutrons, and $\phi$ mesons. Their yields, transverse momentum spectra, and rapidity distributions are simulated separately. These theoretical predictions call for experimental confirmation.

We compare three definitions of $\Xi_c$–$\Xi_c'$ mixing within a constituent-quark model: a spin-component probability angle, a common-source overlap angle, and an SU(3)-breaking mass-operator angle. The probability angle is $3.11^\circ$, while the two operator-based definitions give $2.48$–$2.58^\circ$; a second parameter set gives $2.38$–$2.49^\circ$. The operator-based angles are closer to the lattice determinations $1.2(1)^\circ$ and $0.810(50)(200)^\circ$, but remain larger. We then couple conventional $qsQ$ states to virtual $qsQg$ configurations, where $q=u,d$ and $Q=c,b$. An orbital-$S$-wave chromomagnetic transition containing both $j_{Qg}=1/2$ and $3/2$ raises the source and mass-operator charm angles to $2.67$–$3.16^\circ$ when normalized to reference short-range mass shifts. The hybrid probability stays below $1.7\%$, and the corresponding bottom angles are $0.42$–$0.48^\circ$. Eliminating the hybrid sector gives a rank-one mass correction precisely when all weighted transitions select the same retained-state combination. The mode-resolved calculation separates the flavor-breaking response that changes the mixing angle from the response that generates a second transition direction. The accompanying effective-current relation connects this mass analysis to radiative and semileptonic amplitudes through their current matrix elements.

We derive a density functional for quark matter with linear confinement interaction, applying the principle of saturation of color interactions. For the saturation parameter $\mu$ the ansatz $\mu=k_F$ is suggested, where for the Fermi momentum $k_F \propto n^{1/3}$ going to zero the Cornell potential is obtained and at finite quark densities $n$ an interaction energy density functional $\propto n^{2/3}$ results.

Machine learning (ML) in high-energy nuclear physics (HENP) is entering a new stage in which physical knowledge is incorporated more directly into data analysis, simulation, and physics inference. This mini-review focuses on developments that have matured in the past several years. Whereas earlier applications emphasized event classification, pattern recognition, and surrogate models for selected observables, recent work has moved toward physics-integrated workflows: calibrated Bayesian extraction of QCD matter properties, dense-matter equation-of-state inference from heavy-ion and neutron-star data, generative event modeling, neural unfolding of weak physical signals, differentiable inverse solvers, gauge-equivariant and diffusion-based lattice-field samplers, and neural reconstruction of model functions in holographic QCD. We survey recent applications of ML in heavy-ion collisions, neutron-star physics, lattice QFT, and holographic or continuum QCD. The emphasis is not on ML architectures alone, but on how they enter concrete physics workflows, how physical constraints such as symmetries, conservation laws, causality, thermodynamic stability, and topology are imposed, and how uncertainty quantification and validation determine whether an AI-assisted result can support a reliable physics conclusion.

The hyperspherical-harmonics (HH) expansion does not require uniform resolution: different components of the wave function converge at very different hyperangular and hyperradial scales. We use active learning to exploit this structure, allowing the calculation to distribute resolution instead of prescribing it. The HH space is decomposed into physically identifiable classes whose hyperangular and hyperradial cutoffs evolve independently; a Gaussian-process surrogate learns the marginal variational gain of each admissible extension, and a cost-aware acquisition selects the next one. The surrogate never replaces the many-body solver: every accepted extension is followed by an explicit solution in the enlarged space, so each reported energy is variational in an explicitly constructed basis. We test the construction on $^3$H and $^3$He with the Argonne $v_{18}$ two-nucleon interaction, without and with the Urbana IX three-nucleon interaction, against uniform HH ladders extended to $K=60$ that reproduce established benchmarks within $1$~keV. Asked for $5$~keV, the adaptive runs reproduce the energy of the uniform $K=60$ space within $4$~keV in every case and certify it, leaving more than $60$% of that space unbuilt. The reduction grows as the requested accuracy is relaxed, to about $88$% at $20$~keV and $95$% at $100$~keV. The selected spaces reproduce the known class hierarchy of the trinucleon, and the one-body radii and magnetic moments are converged at about the $2\times10^{-3}$ level (relative error) in the energy-selected space. A run started from the resolution reached by the mirror nucleus, or by the same nucleus with the two-nucleon interaction alone, certifies a smaller space with a third of the exact solves.

We compute the chiral-odd form factors $H_T$, $E_T$ and $\hT$ of the nucleon in light-cone QCD sum rules, separately for the $u$ and $d$ quarks, and organise them into the tensor monopole, dipole and quadrupole moments $g_T$, $\kappa_T$ and $Q_T$. The quadrupole moment, with no chiral-even counterpart at leading twist, and the isoscalar channel, whose sum rules were derived but never evaluated, are new in this framework. The form factors are read from a Lorentz basis independent only after canonical ordering of the Dirac strings; three of the eight surviving structures give the three form factors separately, and the one usually used for the tensor charge is not among the eight. Two exact results follow analytically. The $d$-quark contributions to $E_T$ and $\hT$ are equal and opposite in the chiral limit, broken in proportion to the quark mass and the twist-six amplitude $\mathcal{V}_6$, so the $d$-quark sector carries a single independent function; and the isoscalar tensor charge receives no leading-twist contribution, its twist-three terms cancelling between the flavours. Neither is visible without resolving the flavours. At $\mu^2=1$~GeV$^2$ the two distribution-amplitude sets give $g_T^{u-d}=1.27(7)$, $1.08(6)$, $\kappa_T^{u-d}=1.35(62)$, $1.58(59)$, $Q_T^{u-d}=-4.40(83)$, $-4.20(73)$ and $g_T^{u+d}=0.39(7)$, $0.38(6)$, $\kappa_T^{u+d}=4.47(62)$, $4.32(59)$, $Q_T^{u+d}=2.41(53)$, $1.56(30)$. The mean-field relation $2\hT^{u-d}=-E_T^{u-d}$, tested without any large-$N_c$ assumption, holds in sign and order of magnitude, with ratio $0.64(16)$ and $0.67(15)$ against the predicted unity. In the impact-parameter plane the moments displace the two flavour distributions in opposite transverse directions by nearly equal amounts, $\langle b_y\rangle=0.37$ and $-0.37$~fm, and elongate both across the polarisation axis, the $d$ quark some five to six times more strongly

We have employed Bayesian inference to extract the centroid energies and widths from the isovector giant dipole resonance (IVGDR) data for the IVGDR built on the ground states of nuclei.These IVGDR properties were modeled by explicitly incorporating the structural effects like isospin asymmetry, nuclear deformation and shell correction. The resulting parametrizations reproduce the IVGDR systematics with remarkable precision for both spherical and axially deformed nuclei. Subsequently, the extracted IVGDR parameters were used to constrain the coefficients of the nuclear symmetry energy, which are found to be in good agreement with recent measurements of nuclear dipole polarizability. Furthermore, these symmetry-energy coefficients were employed to predict the dipole polarizability within different self-consistent mean-field models and to investigate its correlation with the neutron-skin thickness. The present findings provide valuable input for large-scale calculations of radiative capture processes relevant to nuclear astrophysics and for improving our understanding of astrophysical scenarios under extreme conditions.

The survival probability $W_{\rm sur}$ of an excited compound nucleus against fission is a key factor determining the evaporation-residue cross section in the synthesis of superheavy nuclei. The $W_{\rm sur}$ for $^{292}$Fl formed in the $^{48}$Ca+$^{244}$Pu reaction was investigated, with particular attention to the coupling between neutron multiplicity and fission competition during the de-excitation cascade. The entrance-channel capture and fusion cross sections are obtained within the dinuclear system model, while the neutron–fission competition is treated using the Vandenbosch–Huizenga formalism with the Kramers and Strutinsky corrections and a fission barrier damped with temperature and angular momentum. The survival probability is calculated using two treatments of the evaporation–fission cascade. In the conventional factorized approach, the realization probability of a given $xn$ channel is treated independently of the neutron–fission competition, with the branching ratios evaluated along a mean excitation-energy trajectory. In the coupled approach, the full excitation-energy population is propagated through the cascade, so that neutron multiplicity and competition with fission are determined simultaneously at the energy actually reached by each nucleus. The comparison shows that the factorized treatment underestimates the $3n$ survival probability by factors of 17 and 24 at $E^*=39$ and 47 MeV, respectively, while its effect on the $4n$ channel is considerably smaller. The resulting $3n$ and $4n$ evaporation-residue excitation functions reproduce eight of the fourteen measured cross sections within a factor of two. A comparison of two prescriptions for the cold fission barrier further shows that differences of less than 1 MeV can change $W_{\rm sur}$ by more than an order of magnitude.

The three gauge couplings of the Standard Model (SM) can be parameterized as the fine structure constant $\alpha$, the weak mixing angle $\sin^2\theta_w$, and the strong coupling $\alpha_s$. They are fundamental constants whose values remain unexplained. Previously we showed that minimizing magic production in charged-lepton scattering reproduces $\sin^2\theta_w$ with great precision. Here we study magic production in the six flavor-diagonal color-singlet channels $q\bar q\to q\bar q$ at tree level, including photon, gluon, $W/Z$, and Higgs exchange. Varying only $\alpha_s$, with all other inputs fixed at each center-of-mass energy, we find that the finite-$\alpha_s$ magic minimum in the top channel reproduces the $\overline{\mathrm{MS}}$ value of $\alpha_s$ to within $5\%$ from $1~$TeV to $10^9~$GeV. Higgs exchange involving the large top Yukawa coupling is essential for this agreement. All six channels produce near-minimal magic at the SM couplings, and reducing $\alpha_s$ toward $\alpha$ increases their magic production, potentially explaining why the strong interaction is “strong.” To understand why minimizing magic reproduces both $\sin^2\theta_w$ and $\alpha_s$, we conjecture that the parameters of fundamental interactions among color singlets reflect a principle of quantum computational efficiency, with the physical universe emerging from a quantum simulation subject to constrained resources.

Radioactive nuclei in neutron-star merger ejecta carry information about both their abundance and their production history. Using the $^{225}\mathrm{Ra}$-$^{225}\mathrm{Ac}$ sequence, we establish exact conditions linking a surviving isotope partition to the time available for parent decay. An Ac fraction of 0.1 produced solely through Ra decay requires at least 2.456 days, providing a direct consistency test for proposed source states. We show that subsequent activity retains additional production memory: two histories with the same mean birth time can produce different response crossings. This distinction is captured analytically and separates mean chronology from the influence of the production-time distribution. A controlled radiation calculation then shows how deposition and photon escape transform the nuclear contrast into a common light-curve pivot for fixed ejecta properties. The results connect nuclear production chronology to late-time merger emission and provide benchmarks for nucleosynthesis and radiation-transport calculations.

Filamentation instabilities are generally regarded as detrimental to fast-electron transport in fusion plasmas because they increase beam divergence and redistribute deposited energy. Here, we use two-dimensional particle-in-cell simulations coupled to a spin-dependent deuterium-tritium fusion module to investigate whether filamentation can instead transfer energy from counterstreaming electrons to prepolarized fusion ions. The simulations show that magnetic filaments, together with longitudinal inductive and transverse charge-separation electric fields, accelerate initially stationary deuterons and tritons to energies at which fusion reactions occur. Over the parameter range examined, the calculated neutron yield increases with the saturated magnetic-field energy. The model further predicts anisotropic, spin-resolved neutron emission. The direction of maximum neutron polarization is approximately perpendicular to the dominant deuterium-tritium collision direction and evolves with the angular distribution of the reacting ions. These results suggest that beam filamentation can couple relativistic-electron energy to fusion ions and that polarized neutron emission may provide a reaction-weighted signature of the underlying plasma dynamics.

We present the first $\textit{ab initio}$ many-body application of the Efros method for scattering utilizing the harmonic oscillator expansion of the continuum wave function. We select single-channel $n\alpha$ scattering and, using low-lying eigenstates from no-core shell model (NCSM) calculations, we obtain well-converged scattering results that are in reasonable agreement with experiment. The results demonstrate that the Efros method is computationally practical and promising for further $\textit{ab initio}$ many-body studies of nuclear reactions.

I propose a Hamiltonian framework for chiral gauge theories (CGT) based on a Euclidean formulation which uses 2n dimensional chiral fermions on the boundary of a 2n+1 dimensional disk. In the original Euclidean formulation, boundary gauge fields were extended into the bulk using $2n + 1$ dimensional gauge field equations of motion (EOM) which creates a bottleneck for constructing a Hamiltonian. I present an alternate proposal for extending the gauge fields into the bulk that is compatible with both a Hamiltonian framework and a Euclidean path integral. Applying this to Abelian gauge fields produces exact expressions of interior fields as a functional of the boundary fields, which can be directly used in a Hamiltonian formulation. Euclidean analysis of the new gauge field extension shows that it can preserve the non-perturbative content of the original construction, including the behavior of topological charge, associated chiral fermion zero modes and an absence of the strong CP problem when applied to the Standard Model. This construction opens up a route to a Hamiltonian treatment and future quantum simulation of CGTs on a disk boundary.

Femtoscopic correlations in proton-proton and heavy ion collisions are commonly calculated using emission sources from microscopic transport models, where emitted particles are represented by classical phase-space points with simultaneously specified positions and momenta. This point-emitter picture neglects the finite phase-space localization required by quantum mechanics, which can become relevant when the localization scale approaches the femtoscopic source size, particularly in small collision systems. We formulate a quantum treatment by replacing each transport phase-space point with a minimum-uncertainty Gaussian phase-space distribution. Finite localization then induces both spatial and momentum smearing; in the presence of coordinate-momentum correlations, the latter produces a nontrivial modification of the emission source. Using proton–proton collisions at $\sqrt{s}=7~\mathrm{TeV}$ simulated with the microscopic Parton–Hadron–String Dynamics transport approach, we show that this effect significantly modifies the proton-pair source and its momentum correlation. Our results expose a quantum localization effect overlooked in transport-based femtoscopy and establish the regime in which the classical point-emitter approximation is valid.