Measurements of Higgs boson Yukawa couplings to Standard Model (SM) fermions constrain radiative mass models for those species. Such models, motivated by the observed fermion mass hierarchy, act as foils for the SM tree-level mechanism: we cannot claim to have verified the standard mechanism if other possibilities also fit the data well. We construct a benchmark model which generates the top mass at tree level and the bottom, charm, tau, and tau Dirac neutrino masses at one-loop level. Current theoretical and experimental constraints on the model, including from Higgs decays, demonstrate it possesses viable regions of parameter space. We show that future improvements to measurements will not be able to rule out the model, only increase the scale of new physics required, illustrating how difficult it will be to verify the SM fermion mass generation mechanism with great precision. As a bonus, a dark matter candidate is shown to be capable of reproducing the correct relic density within the permitted parameter space.

We propose a lattice formulation of the Arf-Brown-Kervaire (ABK) invariant which takes values in ${\mathbb{Z}}_8$. Compared to the standard $\mathbb{Z}$-valued index, the ABK invariant is more involved in that it arises in Majorana fermion partition functions with reflection symmetry on two-dimensional nonorientable manifolds, and its definition contains an infinite sum over Dirac eigenvalues that requires proper regularization. We employ the massive Wilson-Dirac operator, with and without domain walls, on standard two-dimensional square lattices, and use its Pfaffian for the definition. Twisted boundary conditions and cross-caps, which reverse the orientation, are introduced to realize nontrivial topologies equipped with nontrivial ${\mathrm{Pin}}^{-}$ structures of Majorana fermions. We verify numerically (and partly analytically) that our formulation on a torus, Klein bottle, real projective plane (as well as its triple connected sum), and two types of Möbius strip reproduces the known values in continuum theory.

We propose an effective Hamiltonian formulation of quantum field theories using a Daubechies wavelet basis in position space. Combined with flow-equation methods of the similarity renormalization group (SRG), this approach provides an efficient framework for analyzing quantum field theories by reducing the dimensionality of the Hamiltonian and systematically decoupling degrees of freedom across scales. As an application, the free scalar field theory has been reformulated within this framework to calculate the low-lying energy spectrum of the theory. These basis elements are known to transform the free scalar field theory into a theory of coupled localized oscillators, each of which is labeled by a location and a resolution index. In this representation, the Hamiltonian is naturally organized into fixed-resolution blocks, alongside blocks associated with the interactions between different resolutions. To decouple the different resolution modes and obtain a block diagonalized Hamiltonian with each block associated with a fixed resolution, the flow equation approach of SRG is applied. Finally, we demonstrate that with increasing resolution, the low-energy spectrum can be extracted from the effective lowest-resolution block of the Hamiltonian, leading to a significant reduction in computational cost.

We show that rank-ordered jet rapidity distributions provide simple probes of high-energy QCD dynamics at the LHC. Comparing the Balitsky-Fadin-Kuraev-Lipatov-based Monte Carlo (bfklex) to standard event generators based on collinear factorization and Dokshitzer–Gribov–Lipatov–Altarelli–Parisi (DGLAP) parton showers (pythia8, herwig7) in inclusive dijet topologies at 13 TeV, we find clear shape differences. While inclusive distributions can be very similar, rank-ordered spectra reveal that bfklex populates the rapidity interval more democratically, whereas DGLAP showers exhibit stronger edge enhancement and central concentration. We quantify the separation using the total-variation and one-dimensional Wasserstein distances between normalized histograms. The separation persists when applying the harder selection $p_{T,j}>60\mathrm{GeV}$ and $H_{T2}>250\mathrm{GeV}$. Rank-ordered rapidity distributions thus compress exclusive multijet information into simple histograms, offering a new handle on high-energy radiation patterns measurable with existing data.

We study the influence of charm-quark dynamics on the chiral phase structure of QCD using the recently developed miniDSE scheme for the Dyson-Schwinger equations. By comparing the quark and gluon propagators in the $2+1$- and $2+1+1$-flavor setups within the same truncation scheme, we qualify the impact of the charm-quark loop on the QCD phase diagram. Our results show that the charm quark has only a mild effect on the crossover boundary, which remains almost unchanged within the present setup. The most visible effect is a small shift of the critical endpoint (CEP) toward lower baryon chemical potential, by approximately 3%. The present result provides a controlled estimate of the charm-loop effect within the same miniDSE truncation. It indicates that heavy-flavor contributions may become relevant when aiming at precision studies of the CEP location.

The surprising manifestation of collectivity in small collision systems, such as nucleon-nucleon and nucleon-nucleus collisions, is perhaps even more striking when discussed at higher momenta. In larger systems, high-$p_T$ elliptic anisotropy is understood as a selection bias effect due to the smaller energy loss experienced along the shorter direction that aligns with the event plane. However, in small systems the amount of energy loss appears insufficient to reproduce the sizable angular anisotropy observed experimentally. In this work, we explore a new mechanism generating preferred orientations for energetic particles without the need of energy loss. We exploit a simple model that is based on two basic although inalienable ingredients: geometry and quantum mechanics. Our findings suggest that this sum-over-paths mechanism can provide a relevant contribution to so-called flow coefficients of energetic particles traversing deconfined media of any size.

The BESIII Collaboration has recently reported two measurements of the two-photon decay width of the ${\eta }_c$ meson. The 2024 result is significantly larger than most theoretical and empirical expectations, while a subsequent measurement published in early 2026 shows better agreement with the world average and conventional theoretical estimates. In this work, we study the ${\eta }_c\to \gamma \gamma$ and $J/\psi \to \gamma {\eta }_c$ processes within a contact interaction model that incorporates valence-quark anomalous magnetic moment effects, which are absent in standard treatments. Besides achieving agreement with modern lattice QCD estimates for these observables, we find that the 2024 central value for ${\eta }_c\to \gamma \gamma$ lies above the range that could be accommodated by the present framework, whereas the 2026 result is naturally consistent with it.

The cusp structure at the ${\pi }^{+}{\pi }^{-}$ threshold in the ${\pi }^0{\pi }^0$ invariant mass spectrum serves as a sensitive probe for extracting the $S$-wave $\pi \pi$ scattering lengths in processes where an $S$-wave ${\pi }^0{\pi }^0$ pair is produced in the final states. Within the framework of nonrelativistic effective field theory with coupled channels ${\pi }^0{\pi }^0$ and ${\pi }^{+}{\pi }^{-}$, we revisit the near-threshold structures in the ${\pi }^0{\pi }^0$ spectrum of ${\psi }^{\prime }\to J/\psi \pi \pi$. Our analysis incorporates the $\pi \pi$ final-state rescattering, including both strong and Coulomb interactions. It turns out that the cusp near the ${\pi }^{+}{\pi }^{-}$ threshold becomes more prominent when Coulomb interactions are included. The electromagnetic corrections are found to alter the magnitude of the threshold cusp by about 2%–3%, underscoring the necessity of including these effects in precision determinations of the $\pi \pi$ scattering lengths. The coupled-channel amplitude constructed in this work provides a ready-to-use theoretical framework for experimental analyses of fine structures near $\pi \pi$ thresholds.

We complete our study of the relativistic spatial distributions of the energy-momentum tensor inside polarized nucleons within the quantum phase-space formalism. In the present work, we focus on the components of the energy-momentum tensor involving at least one transverse index. We also explore the multipole structure of the transverse distributions in a moving nucleon. In the infinite-momentum frame, we show that the formalism reproduces the standard light-front distributions, including those with a “bad” component, and explains the origin of their structure.

We investigate the reaction mechanism of strangeness production in $K^{-}p\to \varphi \mathrm{\Lambda }$ within a hybrid Regge framework, taking into account $t$-channel $K$- and $K^{*}$-Reggeon exchanges. We present results for the total cross section, $t$-dependent differential cross sections, and spin-density matrix elements (SDMEs), and compare them with the available experimental data. We find that $K^{*}$-Reggeon exchange provides the dominant contribution, while $K$-Reggeon exchange remains non-negligible, particularly in describing the SDMEs. In contrast, the $s$-channel $\mathrm{\Lambda }$ and $u$-channel nucleon exchanges are negligible. To obtain reliable predictions for the open-charm production in $K^{-}p\to D_s^{*-}{\mathrm{\Lambda }}_c^{+}$, we employ a quark-gluon-string-model-motivated Regge prescription that incorporates both pseudoscalar- and vector-Reggeon exchanges. Within this prescription, the Regge trajectories $\alpha (t)$ and energy-scale parameters $s_0$ are determined consistently, thereby constraining the model and reducing theoretical ambiguities. For the hidden-charm production in $K^{-}p\to J/\psi \mathrm{\Lambda }$, we use the same quark-level diagrammatic correspondence. The total cross sections for $K^{-}p\to D_s^{*-}{\mathrm{\Lambda }}_c^{+}$ and $K^{-}p\to J/\psi \mathrm{\Lambda }$ are suppressed by approximately 4–6 and 8–9 orders of magnitude, respectively, compared with that for $K^{-}p\to \varphi \mathrm{\Lambda }$. We also examine possible $s$-channel contributions from the hidden-charm pentaquark states with strangeness, $P_{cs}(4338{)}^0$ and $P_{cs}(4459{)}^0$, to both $D_s^{*-}{\mathrm{\Lambda }}_c^{+}$ and $J/\psi \mathrm{\Lambda }$ production.

We show that small perturbations in the boost-invariant color fields of the glasma exhibit an exponential growth with the square root of time. We interpret this growth rate as a Lyapunov exponent, related to entropy production and the thermalization timescale in the earliest stage of heavy-ion collisions. Working in a regime that is linear in this perturbation, we extract the time dependence of this mode as $\sim \exp (0.4\sqrt{g^2\mu \tau })$ for SU(2), where $g^2\mu$ is proportional to the saturation scale and the square-root dependence is caused by the boost-invariant expansion of the system. We show that the growth rate of this mode is, unlike its amplitude, remarkably insensitive to the details of how the perturbations are initialized. In particular, we show that the unstable mode couples to all momentum scales present in the initial perturbation.

We present an uncertainty-aware description of leading-power fragmentation for all-charm pentaquark states ($S$-wave $|cccc\overline{c}⟩$) at hadron colliders. We construct a multimodal set of collinear fragmentation functions, PQ5Q1.1, incorporating both perturbative and nonperturbative uncertainties. Perturbative effects are estimated via missing higher-order variations, while the nonperturbative wave function is modeled through controlled modifications of its transverse-momentum structure, consistently combined within a replicalike framework. The initial-scale input for constituent charm fragmentation is refined to describe both compact multiquark and diquark-driven production mechanisms. We employ the (sym) jethad interface to study $\mathrm{NLL}/{\mathrm{NLO}}^{+}$ (next-to-leading logarithmic/next-to-leading order) semi-inclusive pentaquark-plus-jet production at the HL-LHC and future Future Circular Collider. The bottom sector is left to future dedicated studies due to its enhanced sensitivity to nonperturbative modeling. Our results provide a flexible framework for uncertainty-controlled predictions, bridging exotic-hadron structure, heavy-flavor fragmentation, and high-energy QCD.

Based on a baryonic extended linear sigma model including explicit chiral symmetry breaking effect, the structure of neutron stars with the emergence of hyperons is investigated using the relativistic mean field approximation. It is found that, except for the lightest scalar meson $\sigma$ whose structure is not well understood so far, the vacuum mass spectra of relevant hadrons and nuclear matter properties around saturation density can be well reproduced. Nevertheless, based on the present model and the applied relativistic mean field approach, we found that, to have a realistic mass-radius relation of neutron stars, the $\pi N$ sigma term ${\sigma }_{\pi N}$ that denotes the contribution of explicit symmetry breaking should deviate from its empirical values at vacuum. Specifically, ${\sigma }_{\pi N}\sim -600\mathrm{MeV}$, rather than (32–89) MeV at vacuum. With an appropriate choice of ${\sigma }_{\pi N}$ and $K(n_0)$, our framework can give a more observationally favored mass-radius relation of neutron stars with the emergence of hyperons, suggesting a possible density dependence of the low energy constants, at least within the present leading order framework with the relativistic mean field approach. The present result provides a new perspective on the relation between microscopic explicit chiral symmetry breaking in dense matter and macroscopic structure of compact stars and calls for more systematic treatments beyond leading order relativistic mean field calculation.

Nonlocal nonstabilizerness (NL NS) and antiflatness provide a measure of the quantum complexity in the wave function of a physical system. Supported by entanglement, they cannot be removed by local unitary operations, thus providing basis-independent measures, and sufficiently large values underpin the need for quantum computers in order to perform precise simulations of the system at scale. Towards a better understanding of the quantum-complexity generation by fundamental interactions, the building blocks of many-body systems, we consider nonlocal nonstabilizerness and antiflatness in two-particle scattering processes, specifically focusing on low-energy nucleon-nucleon scattering and high-energy Møller scattering. We find that the nonlocal nonstabilizerness induced in both interactions is four times the antiflatness (which is found to be true for any two-qubit wave function), and verify the relation between the Clifford-averaged antiflatness and total nonstabilizerness. For these processes, the antiflatness is a more experimentally accessible quantity as it can be determined from one of the final-state particles, and does not require spin correlations. While the Møller experiment at the Thomas Jefferson National Accelerator Facility does not include final-state spin measurements, the results presented here may add motivation to consider their future inclusion.

The ${\mathrm{\Lambda }}_{c}p$ momentum correlation functions are investigated using ${\mathrm{\Lambda }}_{c}N$ interactions derived within the covariant chiral effective field theory. Our analysis reveals that the interaction is weakly attractive in the spin-singlet ${{}^{1}S}_0$ channel. In contrast, the ${{}^{3}S}_1$ channel exhibits a pronounced sensitivity to coupled-channel effects, i.e., the inclusion of $S\text{−}D$ mixing results in a repulsive ${\mathrm{\Lambda }}_{c}p$ interaction; its absence leads to a weakly attractive one. Consequently, the spin-averaged correlation function—dominated by the triplet state weight—exhibits repulsive behavior when the $S\text{−}D$ mixing is present. Furthermore, the source size dependence of the correlation functions is examined, demonstrating that the resulting variations remain experimentally resolvable within the precision of current femtoscopic measurements. A systematic comparison with nonrelativistic chiral effective field theory and phenomenological models yields distinct discrepancies in the femtoscopic correlation functions. These findings underscore the capacity of femtoscopy to discriminate between different theoretical descriptions of the ${\mathrm{\Lambda }}_{c}N$ interaction and provide useful references for upcoming experimental data.

We investigate the finite-temperature SU(2) Savvidy model under an imaginary angular velocity. Employing the background-field method, we derive the one-loop effective potential and analyze both its real and imaginary parts. We demonstrate that imaginary rotation modifies the chromomagnetic condensate and the Polyakov loop, and can partially suppress the Nielsen-Olesen instability of the chromomagnetic background. Moreover, a high-temperature expansion shows that imaginary rotation strengthens the effective coupling and that the chromomagnetic field induces a negative contribution to the moment of inertia.

For the radially excited heavy quarkonia $V=\psi (2S)$ and $\mathrm{\Upsilon }(2S)$, the nodal structure of the wave function renders the three-gluon decay $V\to ggg$ acutely sensitive to relativistic corrections, a longstanding challenge for reliable theoretical predictions. Within the Bethe-Salpeter formalism under the covariant instantaneous ansatz, we construct analytic harmonic-oscillator wave functions incorporating the $2S$ node and derive model-independent relations among the polarized decay widths from helicity-flip and phase-space symmetries. Motivated by the strikingly slow ${\widehat{q}}^2$-order convergence driven by destructive interference at the node, we introduce a concise phenomenological treatment of the higher-order contributions that preserves the correct low-momentum limit. Including both relativistic and QCD radiative corrections, our predictions for $\mathrm{\Gamma }(V\to ggg)$, $\mathrm{\Gamma }(V\to e^{+}{e}^{-})$, and $R_V$ agree well with experiment, and the extracted ${\beta }_V$ lies at the lower end of typical phenomenological ranges, reflecting a more localized momentum-space wave function.

A model-independent parametrization of the low-energy scattering amplitude that incorporates the left-hand cut from one-particle exchange, an extension of the conventional effective range expansion (ERE), was recently proposed and successfully applied to the low-energy $D{D}^{*}$ system [, Effective-range expansion with a long-range force, Phys. Rev. Lett. 135, 011903 (2025)]. While the original formulation is based on a nonrelativistic approximation and is thus limited to a [1, 1] approximant for self-consistency, we extend the framework by explicitly including the higher order terms up to $\mathcal{O}(k^6)$. We systematically investigate the reliability and robustness of the generalized ERE by incorporating relativistic kinematic effects. In addition, we develop a relativistic version of the ERE that accounts for the left-hand cut contributions. These results affirm the generalized ERE as a robust and systematically improvable framework for near-threshold scattering processes, providing both analytical and numerical reliability for applications in two-body scattering problems with a particle exchange.

We employ a simple model for nuclear modification of ordinary parton densities in a proton to evaluate the transverse momentum dependent gluon and quark distributions in nuclei (nTMDs) within the popular Kimber-Martin-Ryskin/Watt-Martin-Ryskin approach. The model is based on a global analysis of available deep inelastic scattering data for different nuclear targets within the rescaling model, incorporating Fermi motion effects. The derived nTMDs are tested with the latest CMS data on inclusive $b$-jet and $B^{+}$ meson production in proton-lead collisions collected at $\sqrt{s}=5.02$ and 8.16 TeV using the high energy factorization framework. We predict the corresponding nuclear medium modification factors to be about of 0.8–1.2 in the probed kinematical region, which is consistent with other estimations. Specially we highlight a possibility to investigate the nuclear modification of parton densities by applying different cuts on the final states in such processes.

We present high-precision predictions for associated $tW$ production at the LHC that incorporate the next-to-next-to-leading-order hard and soft functions as well as the complete next-to-next-to-next-to-leading-order scale-dependent terms derived from the corresponding anomalous dimensions. These higher-order corrections, which dominate the full perturbative results, increase the next-to-leading-order cross section by more than 10%. Based on the comparison with ATLAS and CMS measurements, we directly extract the Cabibbo-Kobayashi-Maskawa matrix element $|V_{tb}|=0.99\pm 0.03(\mathrm{expt})\pm 0.03(\text{theor})$ without assuming unitarity, achieving a precision comparable with the current world average value.