Outflows of rapidly rotating protomagnetars have been considered as attractive sites for the synthesis of nuclei heavier than iron, but the question remains whether these nuclei are able to survive against photodisintegration as they make their way out of their formation environments. In this work, we present new analytic fitting formulas for the photodisintegration cross sections applicable to heavy nuclei beyond iron. We confirm that the results from the TALYS simulations are consistent with the theory of the giant dipole resonance, and apply the obtained new formulas to investigate whether ultraheavy nuclei entrained in protomagnetar outflows can be disintegrated by thermal and nonthermal photons before leaving the stellar envelope. We explore two outflow models: a spherical wind model and a jetted outflow model. For nuclei accelerated to the bulk speed of these outflows, their survival depends on the model and engine properties. For spherical winds, nuclei may survive for the first $\sim 100\mathrm{s}$ postcore collapse, but as the wind Lorentz factor increases, the photodisintegration optical depth sharply rises, and nuclei may no longer survive. For the jetted outflows arising from progenitors surrounded with stellar envelopes, nuclei can only survive before the jet breakout time in cases where the central engine has high spin-down energy, that is, with a high magnetic field strength and shorter spin period. In progenitors with more extended envelopes, the jet breakout time is much longer, allowing for nonthermal photons to readily photodisintegrate nuclei in high spin-down energy cases. These results also outline some of the necessary, but not yet sufficient, conditions to source ultrahigh-energy cosmic-ray nuclei.

Previous studies have shown that cascade production in the thick target of the Search for Hidden Particles (SHiP) experiment may substantially enhance the number of light long-lived particles (LLPs) decaying in the fiducial volume. However, cascade-produced LLPs are typically soft, so daughter-level acceptance and reconstruction effects can strongly suppress the observable event rate. We quantify this suppression for two representative cases: photophilic axionlike particles (ALPs) produced in electromagnetic cascades and heavy neutral leptons (HNLs) produced in decays of secondary kaons. We combine a semianalytic event-rate calculation with a detector-level study of ALP reconstruction in the electromagnetic calorimeter. For the nominal SHiP detector design, cascade ALPs give at most a moderate enhancement over primary production and only at the lightest masses; at higher masses, the cascade contribution becomes subdominant or negligible. For HNLs from secondary kaons, the cascade contribution is already subdominant after imposing daughter-level geometric acceptance. We also identify possible ways to recover part of the cascade event rate, including relaxed event-selection criteria and an active decay-volume subdetector.

We study the collider phenomenology of a long-lived scalar particle $S$ that arises from Higgs mixing in a broad class of Standard-Model (SM) extensions. When the mixing angle is sufficiently small, $S$ becomes long-lived, while its pair production via the Higgs portal can remain sizable. We focus on the production channel $gg\to h^{*}\to SS$ at the LHC, mediated by an off-shell SM-like Higgs boson. This mechanism provides a complementary probe of $S$ in the mass region above the kinematic threshold of the conventional on-shell decay $h\to SS$, thereby extending the accessible parameter space to heavier scalars. The long-lived $S$ particles can decay inside the inner detector, leading to displaced vertices (DVs) accompanied by jets. We perform a detailed Monte Carlo simulation and reinterpret an existing recast of an ATLAS search for DV-plus-jets signatures in this scenario. We also consider a modified analysis strategy based on the same search to assess potential improvements in sensitivity. We find that the current ATLAS search already excludes a significant region of the parameter space, reaching scalar masses up to $m_S\sim 230\mathrm{GeV}$ for a benchmark $hSS$ coupling $\lambda v$ of 246 GeV. The modified analysis and projections to the high-luminosity LHC further extend the sensitivity to wider regions of the mass–lifetime parameter space.

Leptogenesis provides an elegant mechanism to explain the observed baryon asymmetry of the Universe (BAU), yet its experimental verification remains challenging due to requirements of either extremely heavy right-handed neutrinos or precisely fine-tuned mass splittings. We present a scenario where an additional scalar field, coupled to both the Higgs and right-handed neutrinos (RHNs), enhances the $CP$ asymmetry through loop-level contributions, enabling successful leptogenesis at the electroweak scale. This same scalar sector triggers a strong first-order electroweak phase transition (EWPT), producing gravitational waves (GWs) within the reach of next-generation detectors. We demonstrate a robust correlation between the BAU and GW signal strength, providing a falsifiable prediction of leptogenesis that future GW searches can confirm or rule out.

We analyze the prospects for studying scalar nonstandard interactions (SNSI) using the neutrino burst from a galactic supernova (SN). SNSI modifies the resonant flavor conversion and, correspondingly, the neutronization burst signal, and may be identifiable in future multi-tonne-scale experiments, such as Deep Underground Neutrino Experiment (DUNE). Notably, in the normal mass ordering, SNSI can lead to an anomalous (re)appearance of the neutronization-burst ${\nu }_e$ peak at Earth, a feature otherwise strongly suppressed in the Standard Model. We show that, in the presence of SNSI, neutrinos propagating out of the dense SN environment acquire a density-squared-dependent contribution to their mass-squared differences, which in turn modifies the energy levels of the neutrino matter eigenstates. This density-squared effect is absent in less dense environments such as the Earth or the Sun and is precisely what enables SN neutrinos to probe SNSI parameters up to 4 orders of magnitude below the values accessible to solar or terrestrial neutrino sources.

We investigate the long-standing anomaly in the rare decay $B\to K{\mu }^{+}{\mu }^{-}$ within the left-right inverse seesaw (LRIS) model. Global analyses of the $b\to s{\mu }^{+}{\mu }^{-}$ data consistently indicate a significant negative shift in the vector Wilson coefficient, $\mathrm{\Delta }{C}_9^{\mu }\approx -1$, while the axial coefficient $\mathrm{\Delta }{C}_{10}^{\mu }$ remains consistent with zero. We show that a charged-scalar/heavy-neutrino box diagram in the LRIS model naturally generates these values for the Wilson coefficients through a nondecoupling mechanism: the right-handed coupling $Y_{\mu N}^R\propto M_{N_i}/v_R$ produces a contribution to $\mathrm{\Delta }{C}_9^{\mu }$ that is unsuppressed in the heavy-neutrino limit, while the simultaneous presence of a comparable left-handed Dirac Yukawa coupling $Y_{\mu N}^L$ ensures the automatic cancellation $\mathrm{\Delta }{C}_{10}^{\mu }\approx 0$. The potentially dangerous contribution to $B_s-{\overline{B}}_s$ mixing is controlled by the usual Glashow–Iliopoulos–Maiani suppression associated with the top-quark loop, keeping it safely below current experimental bounds throughout the viable parameter space. In addition, a specific right-handed phase texture in the right-handed quark mixing matrix, whose origin can be traced to a discrete $Z_2$ symmetry in the right-handed quark sector, provides a technically natural and radiatively stable structural feature of the model. A numerical scan over the model parameter space identifies a viable region with $y\equiv |Y_{ts,tb}^H|\approx 0.39$ and $M_{H^{\pm }}\gtrsim 600\mathrm{GeV}$, consistent with current flavor and collider experimental constraints.

We come up with a novel search strategy for long-lived doubly charged scalars at future proposed lepton colliders. The doubly charged scalar studied in this work belongs to an $SU(2{)}_L$ complex scalar triplet that accounts for tiny neutrino masses via the type II seesaw mechanism. For scalar masses $\lesssim 200\mathrm{GeV}$ and appropriate values of the triplet vacuum expectation value, this state can be long-lived and decay predominantly into like-sign muon pairs (e.g. ${\mu }^{+}{\mu }^{+}$ or ${\mu }^{-}{\mu }^{-}$), producing distinctive displaced-vertex signals. We investigate the pair production of these scalars at the International Linear Collider (ILC) and a prospective muon collider, considering their planned center-of-mass energies. Incorporating theoretical and experimental constraints, we study the resulting signature of four leptons accompanied by missing transverse energy. Displaced vertices offer direct evidence of the scalar’s long lifetime, while we further show that the invariant mass distribution of same-sign dilepton pairs serves as a powerful complementary probe for discovering doubly charged Higgs bosons at both the ILC and muon collider.

We formulate QCD discretized on the four-dimensional 16-cell honeycomb. The advantage is a higher degree of rotational symmetry as compared to a traditional cubic lattice leading to much smaller cutoff effects. We demonstrate in quenched QCD, through both gluonic and fermionic observables, that the scaling properties are indeed superior to the cubic lattice and much larger lattice spacings are sufficient for controlled continuum extrapolations. Chiral and topological properties also show remarkable improvement.

We study near-threshold $D\overline{D}$ scattering in $S$- and $D$-wave to determine whether or not resonances or bound states are present. Working in the approximation where charm annihilation is forbidden, with two degenerate light-quark flavors and a heavier strange quark, isospin is a good quantum number, and the only other channel that is kinematically open is ${\eta }_c\eta$. Using lattice QCD we compute, as a function of varying light-quark mass, the $S$-matrix for coupled-channel ${\eta }_c\eta -D\overline{D}$ scattering and find only weakly interacting meson pairs. In contrast to several other studies, we find no evidence for any bound-state or resonance singularity in the energy region between the deeply bound ${\chi }_{c0}(1P)$ state and the $D_s{\overline{D}}_s$ threshold.

A pseudoscalar resonance structure, denoted as the $K(1690)$, was recently discovered by the COMPASS Collaboration in the scattering reaction $K^{-}+p\to K^{-}{\pi }^{-}{\pi }^{+}+p$. If the $K(1690)$ is a genuine state, there are three observed pseudoscalar strange mesons, namely the $K(1460)$, $K(1690)$, and $K(1830)$, in the 1.0–2.0 GeV region. However, within the conventional quark model, only the $2{}^1{S}_0$ and $3{}^1{S}_0$ strange meson states are expected in this energy region. Therefore, at least one of these states should be interpreted as an exotic candidate. In this work, we study the spectrum of strange mesons systematically, and find that the $K(1460)$ and $K(1830)$ are good candidates of $2{}^1{S}_0$ and $3{}^1{S}_0$ strange mesons, respectively. A further investigation of their strong decays also supports this assignment. Furthermore, we note that the production mechanism of the $K(1690)$ is similar to that of the ${\pi }_1(1600)$, which has been widely regarded as a hybrid meson candidate. We investigate the strong decays of the $K(1690)$ within a constituent gluon model by treating it as a $0^{-}$ strange hybrid meson and find that the results support the $K(1690)$ as a hybrid state. Finally, we identify several important decay modes of the $K(1690)$ that may be used in future experiments to test whether it contains the $n{{}^{1}S}_0$ ($n=2$ and 3) $s\overline{q}$ component. We also suggest BESIII to search for the $K(1690)$ state through the $J/\psi \to KK(1690)\to K{K}_0^{*}(1430)\pi \to KK\pi \pi$ process.

We present a constituent two-gluon description of the lowest-lying glueball states in pure Yang-Mills theory, calibrated against quenched lattice results. The framework incorporates an instanton-induced dynamical gluon mass, Casimir-scaled adjoint confinement, the short-distance adjoint Coulomb interaction, and instanton-induced central and tensor forces. The scalar $0^{++}$ glueball is found to be exceptionally compact, with a radius of order the instanton size, $\rho \sim \frac{1}{3}\mathrm{fm}$, consistent with lattice indications. By contrast, the tensor $2^{++}$ state remains spatially extended due to the centrifugal barrier. We also discuss the role of $S–D$ mixing. A semiclassical analysis further supports Regge behavior for excited states, in agreement with lattice results.

We search for the reaction channel $e^{+}{e}^{-}\to \eta \eta J/\psi$ in a data sample with center-of-mass energies from 4.226 to 4.950 GeV that was collected by the BESIII detector operating at the Beijing Electron Positron Collider (BEPCII). The data analysis is performed with two different reconstruction methods, exclusive and semi-inclusive, enabling a comparison and combination of the results. Only at a few energy points is a nonzero cross section observed with a statistical significance of more than $3\sigma$ using one of the methods. Therefore, the corresponding upper limits of the cross section at the 90% confidence level are determined. The energy-dependent results show clear deviations from the line shape expected from three-body phase space alone. Since the statistical significance for almost all center-of-mass energies is low, the upper limits for the reaction channel $e^{+}{e}^{-}\to \eta \eta J/\psi$ also serve as limits for the existence of a possible isospin partner to the charmonium-like isospin triplet $Z_{\mathrm{c}}(3900)$ which decays to $J/\psi \eta$.

This work investigates dynamically generated hidden-charm baryon resonances arising from meson-baryon interactions. Using the local hidden gauge formalism, we model the interaction via t-channel vector meson exchange and unitarize the amplitude using the Bethe-Salpeter equation. To address regularization issues, we propose a novel “hybrid loop function” scheme that eliminates the unphysical poles—common artifacts in cutoff or dimensional regularization—while keeping the predictions of physical states. Consequently, the model successfully reproduces six experimentally known hidden-charm pentaquarks as well as earlier theoretical results, and predicts new states in the $S=-1,I=1$ sector.

We investigate saturation effects in exclusive vector meson production in deep inelastic scattering, where we model fluctuations within the target protons as localized color-charge hot spots. Based on the color glass condensate framework and the dipole picture for vector meson production, we examine the dependencies of coherent and incoherent scattering cross sections on the momentum transfer. We draw conclusions on the effectiveness of our hot spot model and the strength of the suppression of the scattering cross sections caused by saturation effects. We find that saturation has mild effects in the given energy and charge-density ranges, but can also show that suppression becomes more prominent as the color-charge density inside the proton increases.

The precise measurement of the $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{\pi }^0$ cross section is performed in the center-of-mass energy range $E=560–1100\mathrm{MeV}$ using a data sample of $66{\mathrm{pb}}^{-1}$ collected in the experiment with the SND detector at the VEPP-$2000e^{+}{e}^{-}$ collider. The systematic uncertainty of the cross section measurement is 0.9% at the maximum of the $\omega$ resonance and 1.2% at the maximum of the $\varphi$ resonance. The leading-order hadronic contribution to the muon magnetic anomaly calculated using the $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{\pi }^0$ cross section measured by SND from 0.62 to 1.975 GeV is $(45.95\pm 0.06\pm 0.47)\times {10}^{-10}$. From the fit to the cross section data with the vector meson dominance model, the parameters of the $\omega$, $\rho$, and $\varphi$ resonances are obtained. The obtained values of $\mathcal{B}(\omega \to e^{+}{e}^{-})\mathcal{B}(\omega \to 3\pi )$, mass and width of the $\omega$ meson, and $\mathcal{B}(\rho \to 3\pi )$ have accuracy better than the current world average values.

Using $e^{+}{e}^{-}$ collision data collected with the BESIII detector at the BEPCII collider corresponding to a total integrated luminosity of $44{\mathrm{fb}}^{-1}$, we present the first measurement of the Born cross sections for the process $e^{+}{e}^{-}\to K_S^0{\overline{\mathrm{\Xi }}}^{+}{\mathrm{\Sigma }}^{-}$ at 56 center-of-mass energies from 3.510 to 4.951 GeV. By fitting the dressed cross sections of $e^{+}{e}^{-}\to K_S^0{\overline{\mathrm{\Xi }}}^{+}{\mathrm{\Sigma }}^{-}$ with the assumption of a power-law function plus a charmonium(-like) resonance, i.e., $\psi (3770)$, $\psi (4040)$, $\psi (4160)$, $Y(4230)$, $Y(4360)$, $\psi (4415)$, $Y(4500)$, $Y(4660)$, and $Y(4710)$, no significant signal of any charmonium(-like) state decaying into the $K_S^0{\overline{\mathrm{\Xi }}}^{+}{\mathrm{\Sigma }}^{-}$ is observed. Upper limits on the product of the electronic width and branching fraction at the 90% confidence level are given for each resonance. Combining this result with the previous measurement of the isospin-symmetric process $e^{+}{e}^{-}\to K^{-}{\overline{\mathrm{\Xi }}}^{+}{\mathrm{\Sigma }}^0$, the ratio of the Born cross sections, $R={\sigma }^B(e^{+}{e}^{-}\to K_S^0{\overline{\mathrm{\Xi }}}^{+}{\mathrm{\Sigma }}^{-})/{\sigma }^B(e^{+}{e}^{-}\to K^{-}{\overline{\mathrm{\Xi }}}^{+}{\mathrm{\Sigma }}^0)$, is found to be consistent with unity.

We introduce equivariant localization as a method for computing the action of probe branes in supergravity backgrounds. We apply it to supersymmetric probe D3-branes in type IIB supersymmetric spacetimes obtained by uplifting the Kerr-Newman-anti-de ${\mathrm{Sitter}}_5$ black hole on a toric Sasaki-Einstein space. Depending on the cycles they wrap, such branes represent nonperturbative corrections to or defect operator insertions in the superconformal index of a large family of four-dimensional $\mathcal{N}=1$ quiver superconformal field theories. The resulting action reduces to equivariant integrals and can be evaluated entirely from toric data.

We study the real-time quantum dynamics of a matrix model consisting two bosonic fields on the fuzzy sphere $S_F^2$ using the Gaussian state approximation. Starting from the Hamiltonian formulation and using Wick’s theorem, we derive a closed set of coupled nonlinear differential equations governing the time evolution of the one- and two-point correlation functions. The thermal equation of state is found by maximizing the von Neumann entropy over Gaussian states and solving the algebraic self-consistency equation(s) leading to a complete determination of the symplectic spectrum of the covariance matrix. We identify near-thermal initial conditions and use them to solve the equations of motion and employ our findings to probe chaos by calculating the largest Lyapunov exponent at various temperatures. Our results demonstrate that the latter tends to zero at a finite temperature indicating that the quantum dynamics respect the Maldacena-Shenker-Stanford bound across all temperatures, while approaching toward the classically chaotic regime at high temperatures. Finally, we examine the entanglement dynamics of the model in real-time by considering a sequence of bipartitions of the Hilbert space and computing the entanglement entropy and clearly exhibit the fast scrambling features that emerge in due detail.

Understanding the properties of strongly interacting matter at extreme densities is a central problem in fundamental physics, with neutron star mergers offering a natural laboratory to probe this regime. However, the complexity of the merger process complicates the interpretation of the associated gravitational-wave and electromagnetic signals. This picture becomes even more complex in the potential scenario in which dark matter accumulates around and in neutron stars, altering their structure and the associated observables. In this work, we study synthetic gravitational-wave observations of binary neutron star mergers with next-generation detectors, investigating their potential to extract both nuclear physics and dark matter constraints. We also examine how the potential presence of fermionic, non-self-interacting dark matter inside neutron stars affects the inference of nuclear empirical parameters. We find that combining observations can tighten constraints on nuclear empirical parameters. However, the inferred values remain sensitive to systematic modeling biases and intrinsic degeneracies among the parameters. Conversely, our analysis reveals that for non-self-interacting fermionic dark matter at mass fractions below one percent, it will be unlikely to find decisive evidence for dark matter when analyzing gravitational-wave signals. Consequently, systematic biases in nuclear empirical parameter inference potentially resulting from such a dark matter component are expected to be negligible even for observations with next-generation gravitational-wave detectors.

We observe that a large class of well-behaved stationary and axisymmetric black hole solutions in general relativity and in the Einstein-Maxwell theory can be classified according to the properties of their backgrounds. Indeed, all these backgrounds belong to a unique family, which includes simultaneously all the known axisymmetric and regular backgrounds: the swirling, the Bertotti-Robinson, the Bonnor-Melvin universe, Witten’s expanding bubble, and also other novel, regular, rotating gravitational or electromagnetic environments. All these can be, fundamentally, traced back to the double Wick rotation of the topological generalization of the (accelerating) Kerr-Newman-NUT metric. We present a black hole embedded in an unexplored sector of the general background: Schwarzschild inside a generalized rotating (and possibly electromagnetic) universe. These results indicate that basically all the known analytical and exact single black hole solutions in the four-dimensional Einstein-Maxwell theory belong to the (accelerating) Kerr-Newman-NUT family embedded into backgrounds that are a subcase of the conjugated Kerr-Newman-NUT spacetime with an angular manifold of arbitrary topology.