We present a comprehensive analysis of the discovery reach and exclusion limits for an ultraheavy diquark scalar (7–9.5 TeV) decaying into a pair of vectorlike quarks (1.5–2 TeV) at the HL-LHC. Building on an improved signal selection efficiency achieved using machine learning techniques, we extend our previous six-jet final-state study by providing a complete likelihood-based statistical treatment of this search topology. The analysis incorporates theoretical and systematic uncertainties through nuisance parameters within the likelihood framework, enabling a consistent statistical interpretation. The mass regions of interest were determined through scans of the local $p$-values, $C{L}_s$, and the upper limits on the model-dependent signal strength $\mu$. The results indicate a promising sensitivity to ultraheavy diquark scalars within the explored mass range, suggesting that the HL-LHC could either discover or set stringent exclusion limits on such particles.

Some extensions of the Standard Model consider inelastic dark matter (iDM) as an attractive candidate for sub-GeV DM of thermal origin that could be detected at modern accelerators. In the present paper, we calculate the production rate of iDM pairs ${\chi }_1{\overline{\chi }}_0$ interacting with the ordinary photon via dipole magnetic moment in the reaction of high-energy electron scattering on nuclei, $e^{-}N\to e^{-}N{\chi }_1{\overline{\chi }}_0$, in the NA64e experiment at the CERN Super Proton Synchrotron (SPS). We derive the projected sensitivity of NA64e to such particles assuming $\simeq {10}^{13}$ 100 GeV electrons on target. We also show, that incorporating heavy vector meson decays, ${\gamma }^{*}N\to NV(\to {\chi }_1{\overline{\chi }}_0)$, alongside bremsstrahlunglike emission of inelastic dark matter pairs, $e^{-}N\to e^{-}N{\gamma }^{*}(\to {\chi }_1{\overline{\chi }}_0)$, will allow NA64e to probe previously unexplored regions of the iDM parameter space, in particular for modest mass splittings, $\mathrm{\Delta }\simeq 5\times {10}^{-2}$, and relatively light masses, $m_{{\chi }_0}\lesssim 100\mathrm{MeV}$.

Symmetries play a crucial role in shaping the structure and predictions of multi-Higgs-doublet models. In three-Higgs-doublet models considerable effort has been put into classifying possible symmetry groups and the conditions for their realization, yet the completeness of existing classifications remains an open question. In this work, we revisit the problem of identifying realizable symmetries by reexamining conventional Higgs family and general $CP$ transformations from an alternative perspective. Our analysis identifies certain limitations in previous approaches and introduces a clearer, more systematic framework for model builders. We expand our classification by investigating more generalized symmetry structures—the recently identified “GOOFy” transformations, which act nontrivially on the Higgs doublets and their conjugates. Our analysis consolidates known results, uncovers previously overlooked structures, and expands the set of symmetries in three-Higgs-doublet models, offering both a clearer theoretical foundation and a practical reference for symmetry-based model building.

We investigate the capability of TianQin and LISA to reconstruct the model parameters in the Lagrangian of new-physics scenarios that can generate an electroweak strong first-order phase transition. Taking the dimension-six Higgs operator extension of the Standard Model as a representative scenario for a broad class of new-physics models, we establish the mapping between the model parameter $\mathrm{\Lambda }$ and the observable spectral features of the stochastic gravitational-wave background. We begin by generating simulated data incorporating time delay interferometry channel noise, astrophysical foregrounds, and signals from the dimension-six model. The data are then compressed and optimized, followed by geometric parameter inference using both Fisher-matrix analysis and Bayesian nested sampling with polychord, which efficiently handles high-dimensional, multimodal posterior distributions. Finally, machine-learning techniques are employed to achieve precise reconstruction of the model parameter $\mathrm{\Lambda }$. For benchmark points producing strong signals, parameter reconstruction with both TianQin and LISA yields relative uncertainties of approximately 20%–30% in the signal amplitude and sub-percent precision in the model parameter $\mathrm{\Lambda }$. The sub-percent precision reflects the statistical reconstruction capability of the detectors in an idealized setting: it incorporates the machine-learning inference uncertainty and is established at a fixed bubble wall velocity, while theoretical uncertainties in the effective potential calculation are not included.

The growth of adiabatic density perturbations during an era of early matter domination induces $\mathcal{O}(1)$ fluctuations in preinflationary QCD axion dark matter across a broad, string-theory-motivated parameter space. Remarkably, at $\mathrm{\Lambda }\mathrm{CDM}$ matter-radiation equality the scale of these perturbations coincides with the quantum Jeans scale, so they collapse to solitonic “axion stars.” These axion stars have densities up to ${10}^4{\mathrm{eV}}^4$, and, including their surrounding halos, they contain as much as 50% of dark matter. Direct searches for a smooth axion background can be suppressed, but transient enhancements or indirect astrophysical signals at axion masses $m_a\lesssim {10}^{-5}\mathrm{eV}$ would point to a nonstandard cosmological history.

We introduce an anomaly-based framework to probe quark electric dipole moments in exclusive hadronic final states produced in $e^{+}{e}^{-}$ annihilation. Chern-Simons-induced anomalous couplings yield a clean T-odd asymmetry $A_T$ from interference between the Standard-Model amplitude and dipole-moment contributions. As an application, ${\gamma }^{*}\to K^{+}{K}^{-}{\pi }^0$ provides direct sensitivity to the strange-quark electric dipole moment (EDM) $d_s$ in the chiral limit. The precision on $d_s$ can reach $\mathcal{O}({10}^{-16})e\mathrm{cm}$ with existing CMD–3 data and $\mathcal{O}({10}^{-18})e\mathrm{cm}$ using current $J/\psi$ samples at BESIII, improving the current direct constraint from hyperon EDM by two to three orders.

The three-flavor framework of neutrino oscillations successfully explains most experimental results, but persistent anomalies at short- and long-baseline experiments hint at the existence of additional light sterile states. In particular, eV-scale sterile neutrinos are motivated by LSND and MiniBooNE results, while sub-eV sterile states with mass-squared differences at the ${10}^{-2}$ and ${10}^{-5}{\mathrm{eV}}^2$ scales have been proposed to address the T2K–$\mathrm{NO}\nu \mathrm{A}$ tension and the absence of the expected upturn in the solar neutrino energy spectrum, respectively. Such sterile states are singlets under the Standard Model gauge group and mix only through their admixture with active neutrinos. In this work, we investigate the phenomenology of the $3+2$ scenario, incorporating one eV-scale sterile neutrino together with a sub-eV state, and analyze their impact on absolute-mass related observables; the sum of neutrino masses $\mathrm{\Sigma }$ constrained by cosmology, the effective electron neutrino mass $m_{\beta }$ from $\beta$ decay, and the effective Majorana mass $m_{\beta \beta }$ probed in neutrinoless double $\beta$ decay. We demonstrate that the presence of two sterile states can significantly modify the allowed parameter space compared to the three-flavor and $3+1$ frameworks, with some mass-ordering schemes already disfavored by current cosmological and laboratory limits. Finally, we assess the implications of upcoming sensitivities from KATRIN, Project 8, and LEGEND-1000, highlighting the complementary role of sub-eV sterile neutrinos in probing physics beyond the minimal three-flavor paradigm.

The particle nature of dark matter (DM) remains one of the central open problems in modern physics. Among the most extensively studied candidates are weakly interacting massive particles, whose parameter space is now under strong pressure from direct detection, indirect detection, and collider searches. In this work we revisit the Higgs-portal scenario with vector DM, first in an effective-field-theory description and then in a renormalizable UV-complete realization. We show that the effective Higgs-portal model with a Proca vector coupled quadratically to the Standard Model Higgs is essentially excluded over almost all of its parameter space by current direct-detection limits, with only a narrow region near the Higgs resonance surviving with a required fine tuning of the DM to Higgs mass that should at the permille level. We then consider a UV completion based on an additional gauged $U(1{)}_X$ symmetry, in which the DM candidate is a massive vector boson $V$ and the scalar sector is extended by a dark Higgs that mixes with the Standard Model Higgs. In this framework, the presence of a second scalar mediator opens an additional resonant annihilation channel and can substantially weaken the direct-detection constraints. In particular, when the DM mass lies sufficiently close to the heavy-scalar resonance, $m_V\simeq m_{H_2}/2$, the coupling required to reproduce the observed relic abundance can lie up to about two orders of magnitude below current direct-detection bounds, thereby opening viable parameter space that is absent in the effective description. Our results highlight the importance of going beyond the effective-field-theory approximation in Higgs-portal vector DM models and show that UV-complete realizations can qualitatively change the phenomenological conclusions.

Top-quark decays are sensitive probes of light charged Higgs bosons ($H^{\pm }$) due to the sizable $t\overline{t}$ production cross section at the LHC in conjunction with their distinct experimental signatures. While dedicated ATLAS and CMS searches considered only $H^{\pm }$ decays into $\tau \nu$, $cs$, or $cb$ for $m_{H^{\pm }}<m_t$, the $WZ$ channel remains unexplored, despite being the dominant mode in $SU(2{)}_L$ triplet models. Since top-quark pair production with $t\to H^{\pm }b$ and $H^{\pm }\to WZ$ gives rise to $t\overline{t}Z$-like signatures, we recast existing $t\overline{t}Z$ analyses to search for signs of charged Higgs bosons and set novel limits on the product of branching fractions $\mathrm{Br}(t\to H^{\pm }b)\times \mathrm{Br}(H^{\pm }\to WZ)$. These constraints turn out to be at the sub-permille level, despite the observed $2\sigma$ preference for a nonzero value. Interpreted within the hypercharge $Y=0$ Higgs triplet model, this translates into a stringent constraint on the triplet Higgs vacuum expectation value of $v_{\mathrm{\Delta }}\lesssim 2\mathrm{GeV}$, which is stronger than those from the $cs,\tau \nu$ modes and even surpasses electroweak precision constraints from the $\rho$ parameter. Moreover, the $2\sigma$ preference for a nonzero cross section further strengthens the cumulative case for a $\approx 152\mathrm{GeV}$ boson as suggested, in particular, by diphoton excesses.

We argue that a simple qubit-regularized SU(2) lattice gauge theory on a plaquette chain serves as a pseudo–one-dimensional toy model for Yang-Mills theory in three spatial dimensions. We map the chain Hamiltonian to the transverse field Ising model in a uniform magnetic field and demonstrate that it can be tuned to a continuum limit in which the short-distance physics is governed by the asymptotically free Ising conformal field theory describing free Majorana fermions, while the long-distance regime contains massive excitations of the $E_8$ quantum field theory that can be interpreted as one-dimensional analogs of glueballs. Furthermore, we find $\sqrt{\sigma }/m_1=0.249(1)$ where $\sigma$ is the string tension between two static quarks and $m_1$ is the mass of the lightest glueball.

We present the first lattice QCD determination of the ${\mathrm{\Xi }}_b\to \mathrm{\Xi }$ vector, axial-vector, and tensor form factors, which are relevant for the theory of rare decays including ${\mathrm{\Xi }}_b\to \mathrm{\Xi }{\ell }^{+}{\ell }^{-}$ and ${\mathrm{\Xi }}_b\to \mathrm{\Xi }\gamma$. The calculation is performed with $2+1$ flavors of domain-wall fermions at three different lattice spacings and pion masses in the range from approximately 430 to 230 MeV. The bottom quark is implemented using an anisotropic clover action. Three-point functions with a wide range of source-sink separations and model averaging are used to extract the ground-state contributions. We fit the dependence of the form factors on the momentum transfer, the pion mass, and the lattice spacing using modified $z$ expansions that account for subthreshold branch cuts, and apply dispersive bounds and asymptotic behavior constraints to achieve controlled uncertainties in the full semileptonic kinematic region. Using our form factor results, we present standard model predictions for the ${\mathrm{\Xi }}_b^{-}\to {\mathrm{\Xi }}^{-}\gamma$ and ${\mathrm{\Xi }}_b^{-}\to {\mathrm{\Xi }}^{-}{\mu }^{+}{\mu }^{-}$ branching fractions and two angular observables.

We study the near-threshold exclusive photoproduction of heavy vector mesons (quarkonia $J/\psi$ and $\mathrm{\Upsilon }$) off the proton within the framework of generalized parton distribution (GPD) factorization. The gluon GPDs are computed using a spectator model in which the proton emits a gluon and the remaining constituents are treated as a single spectator particle. Model parameters are determined by fitting the gluon unpolarized and helicity collinear parton distribution functions from global analyses. We compare our results with the latest near-threshold $J/\psi$ production data from the GlueX and $J/\psi \text{−}007$ experiments at Jefferson Laboratory, finding good agreement for both differential and total cross sections. Predictions are also provided for $\mathrm{\Upsilon }$ photoproduction, which can be tested at future electron-ion colliders.

We present an effective field theory (EFT) framework for coupled-channel $B^{(*)}{\overline{D}}^{(*)}$ scattering, applying it to recent lattice QCD results by Alexandrou et al. [Phys. Rev. Lett. 132, 151902 (2024)]. Two complementary EFT approaches are developed: (1) a low-energy theory near the $B\overline{D}$ ($J=0$) and $B^{*}\overline{D}$ ($J=1$) thresholds, where coupled-channel effects are integrated out; (2) coupled-channel formulation, where all relevant momentum scales are treated as soft, incorporating contact interactions and one-pion exchange (OPE). Importantly, OPE contributes to the lowest channels only through off-diagonal transitions, thus resulting in the appearance of the left-hand cut from two-pion exchange. The two approaches yield mutually consistent results, supporting the existence of shallow bound states in both channels, in agreement with the lattice findings. The finite-volume spectra and extracted pole positions show a near-degeneracy in $J=0$ and $J=1$ channels, consistent with heavy-quark spin symmetry (HQSS). Using HQSS, we predict additional shallow bound states near the $B{\overline{D}}^{*}$ and $B^{*}{\overline{D}}^{*}$ thresholds, which are accessible to future lattice simulations. The effect of OPE on the finite volume spectra is found to be small, with only moderate impact on HQSS partners.

We present a novel algebraic framework for computing hadron properties directly within the contact interaction model. Utilizing Fierz transformations, the method recasts the Bethe-Salpeter dynamics into equations for a minimal set of projected amplitudes for bound-state static properties and form factors, bypassing the conventional need for the meson wave function. This approach is fully demonstrated for the vector meson, enabling the direct extraction of its decay constants, form factors, and the parton distribution functions. The formalism provides a more efficient and unified pathway to hadron observables, with potential for extension to baryons and more sophisticated interactions.

We have made a thorough study of the $D^{+}\to {\pi }^{+}\eta \eta$ reaction, recently measured by the Beijing Spectrometer III Collaboration, which shows an abnormal strength at high invariant masses in the $\pi \eta$ mass distribution. We studied in detail the triangle mechanism and the $f_0(1370)$ excitation modes that have been suggested to explain this abnormal feature, and concluded that they are too small to have any important role in the solution to that problem. We have also studied other possible solutions, evaluating the contribution of excitations of other $f_0$, $a_0$ and $f_2$ resonances, and reached the same conclusion. Unexpectedly, the solution to the problem is found considering the $f_0(980)$ excitation, with the $f_0(980)$ decaying to two $\eta$, which is tied to the $a_0(980)$ production, and well under control. At the same time, the consideration of the $f_0(980)$ excitation solves another nonreported problem, which is the $\eta \eta$ mass distribution that comes when only the $a_0(980)$ resonance is allowed to be excited, which produces a large deficiency at low invariant masses compared with experiments.

It is well known that the diffusion equation, when treated as a stand-alone partial differential equation, exhibits exponential instabilities in boosted frames, which render the corresponding initial value problem ill posed. Recently, however, it was shown that Fick-type diffusion arises as the exact hydrodynamic sector of relativistic Fokker-Planck kinetic theory. In this work, we exploit this kinetic embedding to formulate a modified initial value problem for one-dimensional Lorentz-boosted diffusion. We show that the resulting dynamics are well posed both forward and backward in time, provided the boosted density profiles admit a kinetic-theory realization. Such profiles form a space of band-limited functions, within which the evolution can be expressed as a discrete superposition of spatially sampled initial data, weighted by a Shannon-Whittaker-type Green’s function defined on the full Minkowski plane. The Green’s function is obtained in closed analytic form.

We present the TQ4Q2.0 fragmentation functions for the production of all-heavy (fully heavy) $S$-wave tetraquarks ($T_{4Q}$) with scalar ($0^{++}$), axial-vector ($1^{+-}$), and tensor ($2^{++}$) quantum numbers in high-energy hadronic collisions. This work extends the previous TQ4Q1.1 framework by incorporating nonconstituent heavy-quark contributions and introducing a replica-based uncertainty-quantification strategy derived from multiscale variations (MHOUs). The construction follows a nonrelativistic quantum chromodynamics (QCD) factorization approach, combining gluon- and heavy-quark-initiated fragmentation channels at leading power. Initial-scale inputs are modeled through updated potential-inspired wave functions, while the subsequent Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution is performed via the threshold-aware HF-NRevo scheme. A comprehensive systematic analysis of uncertainties is carried out, with contributions from color-composite long-distance matrix elements (LDMEs) and perturbative multiscale inputs. The resulting TQ4Q2.0 grids, publicly released in LHAPDF6 format, provide the first complete phenomenological set for all-heavy exotics, enabling precise studies of all-charm tetraquark production and jet-associated observables within the jethad environment. This article completes the high-energy resummation-driven generation of the TQ4Q program and establishes a definitive baseline for future collider-oriented analyses of all-heavy multiquark dynamics.

We study the spin-dependent cross section in semi-inclusive deep-inelastic lepton-nucleon collisions, $\ell +N^{\uparrow }\to \ell +h+X$. We focus on the cross section that is integrated over the transverse momentum ${\mathit{P}}_{h\perp }$ of the detected unpolarized hadron. We analyze this cross section at large virtuality $Q^2$ of the exchanged virtual photon within the framework of collinear twist-3 factorization in perturbative QCD. The two main transverse spin observables, the single nucleon spin asymmetry, and the double longitudinal lepton-transverse nucleon spin asymmetry, both receive contributions from chiral-odd twist-3 three-parton fragmentation functions. We study these fragmentation contributions to next-to-leading order (NLO) in perturbative QCD. We explicitly observe that collinear twist-3 factorization holds for these contributions at the one-loop level. We confront our NLO formulas with HERMES data and provide numerical predictions for EIC kinematics.

Charged spin-1 (vector) particles behave very differently from electrons or scalars in a Coulomb field. For an infinitely heavy “pointlike” nucleus, their bound-state wave functions “fall to the center,” and embedding the system in a renormalizable electroweak-type theory does not remedy this short-distance pathology. We therefore solve the pure Coulomb problem for a finite nuclear radius $R$ and recover the point-nucleus limit by letting $R\to 0$. This approach allows us to include the crucial $\mathrm{\Upsilon }$-term in the wave equations, which for the pointlike nucleus is proportional to $\delta (r)$ and was ignored in the previous calculations of the energy spectrum. Several unusual effects emerge: (i) The $\mathrm{\Upsilon }$-term supports a tower of states located mainly inside the nucleus. As $R\to 0$ their number diverges, most lying in the negative-energy continuum (energy $\epsilon <-m{c}^2$). They trigger vacuum breakdown—particle-antiparticle pair creation that ultimately screens the nuclear charge. (ii) Ordinary Sommerfeld-like states (with binding energy smaller $m{c}^2$) persist, but a finite fraction of each wave function leaks into the nucleus, even as $R\to 0$. (iii) Charge density of a negatively charged vector particle changes sign in a vicinity of the nucleus and becomes positive charge density, whereas the $\mathrm{\Upsilon }$-term ensures its density inside the nucleus remains negative. (iv) For weak coupling, $Z\alpha \ll 1$, yet with $mR<Z\alpha$, the “nonrelativistic” solution differs qualitatively from Schrödinger theory despite binding energies that are well below $m{c}^2$; agreement is recovered only when $Z\alpha \ll mR$. These phenomena highlight the distinctive and subtle behavior of spin-1 particles in the Coulomb field.

We report a measurement of the branching fraction for the leptonic decay $B^{+}\to {\mu }^{+}{\nu }_{\mu }$. This work presents the first $B^{+}\to {\mu }^{+}{\nu }_{\mu }$ result using Belle II data, an updated Belle measurement that supersedes the previous result, and their combination, which yields the most precise search to date. The analysis is based on $1076{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ collision data collected at a center-of-mass energy of 10.58 GeV with the Belle and Belle II detectors at the KEKB and SuperKEKB colliders, respectively. We measure $\mathcal{B}(B^{+}\to {\mu }^{+}{\nu }_{\mu })=(4.4\pm 1.9\pm 1.0)\times {10}^{-7}$, where the first uncertainty is statistical and the second systematic. The observed significance relative to the background-only hypothesis is 2.4 standard deviations. We set a 90% confidence level upper limit of $\mathcal{B}(B^{+}\to {\mu }^{+}{\nu }_{\mu })<6.7\times {10}^{-7}$ using a frequentist approach and a 90% credibility level upper limit of $\mathcal{B}(B^{+}\to {\mu }^{+}{\nu }_{\mu })<7.2\times {10}^{-7}$ using a Bayesian approach. These are the most stringent limits to date. The result is interpreted as an exclusion region in the parameter space of type II and type III two-Higgs-doublet models. We search for stable sterile neutrinos with masses $m_N\in [0,1.5]\mathrm{GeV}$. No signal is observed, and the resulting exclusion on the squared mixing parameter $|U_{\mu N}{|}^2$ provides improvement over previous limits. We report a measurement of the partial branching fraction of semileptonic $B\to X_u\ell {\nu }_{\ell }$ decays with $p_{\mu }^B>2.2\mathrm{GeV}$, obtaining $\mathrm{\Delta }\mathcal{B}(B\to X_u\ell {\nu }_{\ell })=(2.72\pm 0.05\pm 0.29)\times {10}^{-4}$. We present a model-dependent study of weak annihilation decays using the muon momentum spectrum. We observe a signal of 2.4 standard deviations above the background-only hypothesis in regions where the distribution resembles that of $B\to X_u\ell {\nu }_{\ell }$ decays.