We propose a framework for fermion mass generation based on a universal seesaw. The Standard Model is extended by an Abelian gauge symmetry acting on right-handed fermions, together with vectorlike fermions and scalar fields. The ordinary Yukawa couplings are forbidden, except for the top-quark coupling to the Higgs, which is allowed at the renormalizable level and remains unsuppressed. The charged-fermion hierarchies then arise from mixing with the vectorlike sector, and light neutrino masses emerge from a neutral sector Majorana seesaw. $CP$ is exact in the ultraviolet and broken spontaneously by scalar vacuum expectation values. The resulting $CP$-violating phase is transmitted to the quark sector and generates the Cabibbo-Kobyashi-Maskawa (CKM) phase, while a Nelson-Barr structure, realized through the universal seesaw block form, keeps the physical QCD vacuum angle zero at tree level. Consistency with electric dipole moment (EDM) bounds beyond tree level requires moderately suppressed Yukawa couplings between SM doublets to the vectorlike sector. If the leading higher-dimensional operators are unsuppressed, the same requirement can favor a low breaking scale for the new Abelian symmetry. In this regime the vectorlike fermions can lie at the TeV scale, with suppressed mixing with the electroweak sector. This framework provides a simple setting in which the hierarchies of charged-fermion masses, neutrino masses, and $CP$-violating parameters can be accounted for within a common extension of the Standard Model.

Jiang and Liu [The holographic dual of the GHZ state, arXiv:2508.17898] proposed the booklet wormhole as the holographic dual of the GHZ state. The geometry is not a manifold because multiple spacetime boundaries meet at a multiway junction. This paper extends the investigation into this geometry, particularly focusing on the junction conditions for matter fields. First, we show that the multiway junction in our construction is topological, such that no single observer will perceive the junction, and the spacetime they experience returns to a smooth manifold. Second, the symmetry of the GHZ state requires unprecedented quantum nonlocal junction conditions at the multiway interface: observers entering from different horizons will perceive different states inside the wormhole, where the junction conditions appear as constraints on the observables of different sets of observers. We finally discuss how to render booklet wormholes traversable via boundary deformations. A localized wave packet injected from one page generally evolves into a nonlocal mixed state on each remaining page, with the information encoded in the entanglement between different pages.

A field theory in $3+1$ dimensions contains two fermions, two Abelian gauge fields, and one complex scalar, with dynamics fixed by a Becchi-Rouet-Stora-Tyutin (BRST) symmetry. For a specific parameter configuration, the fermion mass matrix becomes non-Hermitian, and the propagators exhibit complex-conjugate poles. We evaluate the one-loop fermion contribution to the scalar two-point function. Once the factor $i$ of the $e^{iS}$ normalization is removed, the contribution is real for real external momentum below the threshold $(m+m^{*}{)}^2$ of the two constituents, which follows from the pairing of complex-conjugate terms in the loop integral. The thresholds of the equal-mass pairs sit at complex $p^2$ and generate no cut on the real axis, while the mixed pair, whose constituent masses add up to the real number $m+m^{*}$, opens a cut. Across this cut, the upper and lower boundary values are related by complex conjugation, so that the associated spectral density is real. Its positivity is not established here. The BRST construction of the action provides the starting point for an algebraic renormalization analysis.

The evolution of the event horizon when two black holes merge can be determined by resorting to ray-tracing techniques on a single black hole spacetime, under the assumption that the binary’s mass ratio is infinite and the underlying gravity theory respects the equivalence principle. We extend this analysis to the collision of nonspinning hairy black holes in Einstein-scalar-Gauss-Bonnet gravity. In such theories the scalar field is coupled to a higher curvature operator, leading to possible modifications of the background geometry and consequently of photon propagation. We study three families of coupling functions: linear, quadratic, and a particular exponential form. The first choice enjoys a shift symmetry and forces the presence of scalar hair in the spectrum of black hole solutions. The latter two couplings break the shift symmetry and allow for spontaneously scalarized hairy black holes, which coexist with the Schwarzschild black hole. For all three classes of theories studied, we find a merger duration that is longer than the corresponding time in general relativity, when keeping the size of the small black hole fixed and for viably small values of the coupling constant. However, the case of the exponential coupling yields a nonmonotonic merger duration, which can become shorter than the general relativity value for a sufficiently large coupling constant. We observe that the merger duration and the area increment generically track the behavior of the small black hole’s photon ring. Finally, we also compare our results with recent numerical simulations by other groups, despite the dissimilar mass ratios considered.

We study black holes in shift-symmetric scalar Gauss-Bonnet gravity extended by a cubic Galileon interaction with a distinct energy scale. Introducing this hierarchy profoundly modifies the theory’s phenomenology. The cubic interaction allows for smaller black holes, and can generate a screening mechanism near the horizon, making large Gauss-Bonnet couplings consistent with gravitational-wave bounds. Observable quantities such as the scalar charge, the innermost stable circular orbit, and its frequency are most affected for small black holes. The resulting multiscale effective field theory remains technically natural and offers new avenues to probe gravity in the strong-field regime.

In shift-symmetric Einstein-scalar-Gauss-Bonnet gravity, stationary black holes have a nonvanishing scalar charge. During the inspiral, the phase evolution is modified by several effects, primarily an additional scalar dipole radiation, which enters at $-1\mathrm{PN}$ order. Including corrections up to 2PN, this effect accelerates the inspiral when compared to general relativity, but changes in the conservative dynamics may do the opposite. Using fully nonlinear numerical simulations of quasicircular, comparable mass binaries, we characterize the late stages of the orbital dynamics. We find that the overall effect is still an accelerated merger phase for the modified gravity case, but noticeably less than predicted by Post-Newtonian (PN) alone, which we relate to the conservative dynamics, showing that at the late inspiral stage more energy must be emitted in scalar-Gauss-Bonnet gravity to induce a given change in frequency. In longer signals, this may lead to a distinctive frequency evolution relative to general relativity as the binary approaches merger, but its effect close to merger is to suppress the difference with GR. This work suggests we may need to revisit existing constraints on the theory that are obtained assuming PN approximations apply up to merger, or based on order by order approximations that neglect backreaction effects on the metric, and shows the importance of including nonlinear effects that modify the gravitational sector in the strong field regime.

Under normal circumstances, an observer falling into a black hole feels nothing special upon crossing the horizon. In this paper we find an intriguing exception: for most of the parameter range of the extremal Kerr-Newman (KN) spacetime, horizon corotating perturbations are enhanced near the horizon, such that an infalling observer experiences an anomalously large tidal deformation as they enter the black hole. Such perturbations arise when there is a persistent source outside the black hole that is either corotating itself or has discrete Fourier support at the associated frequencies $\omega =m{\mathrm{\Omega }}_H$ (where $m$ is the azimuthal number and ${\mathrm{\Omega }}_H$ is the horizon frequency). The enhancement is formally infinite at precise corotation, and we work with a nearly corotating mode to keep perturbation theory under control. The underlying physics is the emergence of discrete self-similarity in the extremal limit, with complex scaling weights of the form $-1/2\pm i\alpha$ for real $\alpha$. It is analogous to the black hole Meissner effect, except that the near-horizon field is enhanced rather than screened. We numerically calculate the scaling exponents for coupled gravitoelectromagnetic (GEM) perturbations of extremal KN black holes and show that the complex exponents arise in the parameter range $Q<Q_{*}$ with $Q_{*}\approx .93M$. These exponents also predict the decay and growth rates (Aretakis effect) of generic GEM perturbations of the KN spacetime, both on and off the horizon. The enhancement of corotating perturbations can be viewed as a driven Aretakis instability.

We revisit accretion of an asymptotically uniform fluid onto a moving Schwarzschild black hole, the relativistic analog of Bondi-Hoyle-Lyttleton accretion. Expanding on previous treatments, we focus on relativistic accretion of stiff fluids with adiabatic indices $\mathrm{\Gamma }\ge 5/3$, which is particularly relevant for the treatment of primordial black holes captured by neutron stars. We perform numerical simulations to systematically explore the dependence of the steady-state accretion and drag rates on the asymptotic sound speed $a_{\infty }$ and relative speed $v_{\infty }$, and identify different regimes, both subsonic and supersonic, in which these rates either increase or decrease with respect to the spherical accretion rate for $v_{\infty }=0$. We propose simple analytical approximations that capture the qualitative features observed in the dependence of the accretion and drag rates on $a_{\infty }$ and $v_{\infty }$.

Dark matter consisting of ultralight bosons can form a macroscopic Bose-Einstein condensate with distinctive observational signatures. While this possibility has been extensively studied for axions and axionlike particles—pseudoscalars with masses protected by shift symmetry—realistic models from string theory and other higher-dimensional theories predict more complex structures. Here we investigate a two-field generalization where an axion couples to a moduli field through its kinetic term, representing the phase and radial modes of a complex scalar field. We demonstrate that when this system forms a gravitationally bound Bose-Einstein condensate, the kinetic coupling produces dramatic modifications to cosmological evolution compared to the canonical single-field case. Most notably, the axion Jeans scale becomes dynamically dependent on the moduli field’s evolution, fundamentally altering structure formation. By mapping existing observational constraints from canonical axion models to our two-field scenario, we identify regions of parameter space that are already excluded by current observations. In particular, consistency with observations requires that the moduli field must take on small field values, $\chi /M_{\mathrm{pl}}\ll 1$, throughout most of cosmic history for this class of axions to remain a viable description of all dark matter.

We study solitonic cores in the Thomas–Fermi regime of self-interacting scalar field dark matter (SI-SFDM) and assess whether strong gravitational lensing by galaxy clusters can detect or constrain them. We build composite halo profiles that join a solitonic core to an outer Navarro-Frenk-White (NFW) profile at fixed total mass, and compute their lensing signatures—the deflection angle and the excess surface mass density—for two halos of typical cluster scale, $M_{200}=2\times {10}^{15}$ and $2\times {10}^{14}{M}_{\odot }$. The soliton radius is fixed by the microphysics ($m$, ${\lambda }_4$), while its mass is not fixed by these parameters but is constrained by the halo mass budget. Lensing constrains only the radius, and hence the combination ${\lambda }_4/m^4$; combined with the independent bound on the self-interaction cross section, this places an indirect upper bound on the scalar field mass, $m\lesssim \mathrm{few}\times {10}^{-5}\mathrm{eV}$, and correspondingly ${\lambda }_4\sim {10}^{-18}$. Taking the NFW profile as reference, we quantify the deflection-angle difference produced by the soliton and confront our predictions with the cluster A2390 and with the stacked DES weak-lensing profile to assess when an SI-SFDM core can be distinguished from NFW.

We present constraints on ultralight bosons using binary black hole mergers observed in the second and third parts of the fourth LIGO-Virgo-KAGRA observing run. Directed searches are conducted for long-transient gravitational waves from ultralight vector boson clouds around merger remnants, using a hidden-Markov-model (HMM) tracking scheme. We target the remnant black holes formed in the binary coalescences that produced GW250114 and GW250207. We find no evidence for such signals from either target. Estimating our search sensitivity at a threshold corresponding to a 1% false alarm probability, we thus disfavor vector boson masses in the range of $[2.80,3.95]\times {10}^{-13}\mathrm{eV}$ with greater than 90% confidence. In addition, we derive constraints on ultralight scalar and vector bosons from the inferred high spins of the constituent black holes in three binaries, using events GW240515, GW241113, and GW241225_08. The excluded mass ranges in this approach depend on the assumed black-hole ages. At ${10}^5\mathrm{years}$, corresponding to typical dynamically formed binaries, we exclude scalar and vector bosons in the ranges $[1.39,6.94]\times {10}^{-13}\mathrm{eV}$ and $[0.32,14.4]\times {10}^{-13}\mathrm{eV}$ at 90% confidence, respectively.

Millisecond pulsars (MSPs) are abundant in globular clusters (GCs) and probably also in galactic nuclei. They offer the potential to form a miniature pulsar timing array (mini-PTA) to detect nanohertz gravitational-wave (GW) sources located inside the array. Since the size of such an array is comparable to the wavelength of GW, the conventional plane-wave approximation becomes invalid, and near-field effects, including wave front curvature, the nonradiative self-field of the GW source, and direct perturbation of pulsar by GW, become significant. In this work, we incorporate these effects in a comprehensive model to calculate the timing residual induced by a GW source inside a mini-PTA. We also consider realistic GW source configurations in GCs (M15 and $\omega$ Centauri) and in galactic nuclei (Sgr A* and M31), and find that for MSPs located sufficiently close to the GW source (within a few wavelengths), the residual can reach $1\mathrm{\mu }\mathrm{s}$ in GCs and up to milliseconds in galactic centers, within the potential detection reach of current radio telescopes. Crucially, when the pulsar lies within a few GW wavelengths of the source, the nonradiative field dominates and causes the residual to rise much more steeply (between $1/r_e^2$ and $1/r_e^4$, where $r_e$ is the distance to the source) than the conventional far-field scaling ($1/r_e$). These results demonstrate that mini-PTAs in GCs or galactic nuclei can serve as powerful probes of otherwise invisible GW sources, including intermediate-mass and supermassive black hole binaries.

Vector meson dominance models describe the mixing of photons with vector mesons; the hadronic admixture frequently dominates the interactions of photons with nucleons. This mixing also makes it possible to test for new physics affecting the vector mesons using photon measurements. The possibilities for new physics to be constrained in this indirect fashion include potential Lorentz and $CPT$ violations in the hadronic effective action. The characteristic scale of bounds on Lorentz violation coefficients in the ${\rho }^0$ meson sector is two orders of magnitude weaker than the corresponding photon bounds, three orders of magnitude weaker for $\varphi$ vector mesons, and four orders of magnitude weaker for $\omega$ mesons.

We consider a self-interacting charged scalar field represented by the complex $\lambda {\varphi }^4$ model, embedded in a background electric field exhibiting classical stochastic fluctuations. We studied the effects of the classical stochastic noise on the physical parameters of the scalar field theory, for both weak and ultrastrong electric-field regimes. The stochastic background electric field is included in the Schwinger propagator through the covariant derivative, and the generating functional of the theory is found by means of the replica trick in order to compute the statistical average over electric fluctuations. As a result of the averaging process, an effective interaction between charged currents emerges, with a coupling constant proportional to the magnitude of the autocorrelation function of the electric-field fluctuations. We obtained the dressed propagators, the interaction vertices, and the renormalization group equations of the theory, along with the corresponding streamplots in the manifold of interaction couplings.

The diffusion of high-energy cosmic rays (CRs) through the dark matter (DM) spikes of active galactic nuclei entails significant energy loss via interactions with DM. While previous studies of sub-GeV DM have focused on elastic scattering, this process becomes insufficient at higher proton energies and DM masses. In this work, we investigate the CR-DM deep inelastic scattering (DIS) as mediated by a vector portal. We calculate the DIS contribution to the CR energy loss rate and derive stringent exclusion limits on the CR-DM scattering cross section for DM masses between ${10}^{-6}\mathrm{GeV}$ and 1 GeV. For higher CR energies and mediator masses, the resulting CR cooling timescales are reduced by orders of magnitude after involving the DIS contribution, producing stringent constraints that surpass most of current experimental limits.

Since its first observation by the ATOMKI experiment in 2018, the *Be anomaly has attracted considerable interest within the dark sector community as it may indicate the existence of a new fundamental particle with a mass of about 16.9 MeV, the $X_{17}$. However, the minimal model describing $X_{17}$ as a new vector boson is severely constrained by null results from legacy beam-dump experiments. Among these, the E141 experiment at SLAC places stringent limits on the $X_{17}$ coupling to electrons ${ϵ}_e$ in the $5.1\times {10}^{-5}\lesssim {ϵ}_e\lesssim 1.7\times {10}^{-4}$ region. This excludes the possibility of a long-lived $X_{17}$, potentially in contrast with the preliminary estimate of the particle lifetime recently reported by the ATOMKI Collaboration. The E141 limits commonly adopted in the literature rely on reinterpretations of the original analysis under solid but simplifying assumptions. While these studies provide a reliable estimate of the experiment’s reach, they rely on approximations that were well justified when the boson mass was largely unconstrained. With the $X_{17}$ mass now confined to a narrow region by recent experimental observations, a more refined treatment of the E141 sensitivity becomes necessary. In this work, we revisit the E141 exclusion limits in the $X_{17}$ scenario by performing a dedicated reanalysis that incorporates a more accurate treatment of the experimental setup and signal prediction. We quantify the impact of these refinements on the excluded parameter space and discuss their implications for the compatibility between the E141 constraints and the vector-boson interpretation of the ATOMKI anomalies.

We present a systematic study of the scalar electromagnetic and spin polarizabilities of spin-$1/2$ singly charmed baryons at $\mathcal{O}(p^4)$ within the framework of heavy baryon chiral perturbation theory. Our results show that the higher-order corrections to the electric polarizability are small, while those to the magnetic polarizability are relatively larger due to the small mass splitting of singly charmed baryons and are closely related to transition magnetic moments. Furthermore, we find that the spin polarizabilities of singly charmed baryons, except for ${\gamma }_{M1M1}$, are much smaller than those of the nucleons. We have also calculated the polarizabilities for singly bottom baryons, with the results showing generally larger values than those of singly charmed baryons.

In this work, we study the ${\mathrm{\Omega }}_c$ baryon spectrum up to the $2P$ excitations within a semirelativistic constituent quark potential model, where the mixing between different configurations with the same spin-parity numbers is dynamically considered. Furthermore, the strong decay properties for the excited ${\mathrm{\Omega }}_c$ states are evaluated within an improved chiral quark model by including the relativistic correction term. In a unified framework, we provide a reasonable explanation of the widths, masses, and mass splittings, for the newly observed ${\mathrm{\Omega }}_c$ resonances ${\mathrm{\Omega }}_c(3000)$, ${\mathrm{\Omega }}_c(3050)$, ${\mathrm{\Omega }}_c(3065)$, ${\mathrm{\Omega }}_c(3090)$, ${\mathrm{\Omega }}_c(3120)$, ${\mathrm{\Omega }}_c(3185)$, and ${\mathrm{\Omega }}_c(3327)$. It is found that the configuration mixing is crucial for understanding the strong decay properties and mass splittings, while the relativistic correction term of the strong transition operator plays an important role in the states dominated by the radial excitations. We expect our study can provide useful references for establishing a more abundant ${\mathrm{\Omega }}_c$ spectrum.

The enhancement of the baryon production relative to mesons in small-collision systems is considered a breakthrough result of the Large Hadron Collider since a similar effect in heavy-ion collisions is understood by invoking the formation of the strongly interacting quark-gluon plasma. In this paper, a baryon enhancement is reported for $p_{\mathrm{T}}^{\mathrm{ch},\mathrm{jet}}>15\mathrm{GeV}/c$ jets produced in pp collisions at $\sqrt{s}=13\mathrm{TeV}$ simulated with pythia8. The effect can be explained as a transition between quark-initiated jets (low jet multiplicities) to gluon-initiated jets (high jet multiplicities). The present result contributes to a deeper understanding of the multiplicity dependence of baryon enhancement across different collision systems.