Papers

We study the high-temperature vacua of the Standard Model from the perspective of generalized symmetries and the global structure of the gauge group. We analyze the one-loop effective potential for Polyakov loop holonomies, incorporating the gauge identifications induced by gauging discrete subgroups of the electric one-form symmetry. This provides a classification of physically inequivalent vacua for each gauge-group quotient. We further comment on the effects of additional center-charged matter on the residual one-form symmetry and the vacuum structure.

Motivated by the anticipated data rates of the high-luminosity phase of the Large Hadron Collider, we report the first predictions up to next-to-leading order in quantum chromodynamics with parton-shower matching for the production and decay of scalars and heavy neutrinos from the Scotogenic model for neutrino masses and dark matter at $\sqrt{s}=14$ TeV and $\sqrt{s}=100$ TeV. We carry out our simulations using the FeynRules+MadGraph5\_aMC@NLO+Pythia8 pipeline. As a byproduct, we report the public release of the SM\_Scoto Universal FeynRules Object libraries for modeling the Scotogenic model in high-energy processes. We comment on prospects of observing new rare $Z$ decays at future $e^+e^-$ collider facilities as well as on the production of new particles at a multi-TeV $\mu^+\mu^-$ collider.

The high-energy nuclear-recoil candidate reported by LUX-ZEPLIN could point to dark matter beyond the reach of the LHC. We examine how future colliders could test this interpretation, starting with the thermal Higgsino and extending to a broad class of electroweak multiplets containing neutral and charged particles. We assume an approximately pure multiplet protected by an exact stabilizing symmetry, with dominant inelastic Z exchange and the full dark-matter abundance set by gauge-dominated thermal freeze-out, where mixing and additional interactions affecting production or freeze-out are negligible. In this setting, heavy thermal masses, rare production and invisible neutral transitions make the Higgsino's main collider obstacles generic across the class, independently of supersymmetry. Charged lifetimes vary, but the benchmark spectra studied, including radiative doublet splittings, remain beyond the projected HL-LHC reach. We show how FCC-hh and a high-energy muon collider can overcome these obstacles. Our FCC-hh estimates show sensitivity to the doublets and several larger multiplets through disappearing charged tracks and complementary channels that do not depend on the charged lifetime. Muon-collider projections cover the fermionic doublet and triplet at 10 TeV and the full fermionic family considered here at 30 TeV, subject to the stated spectrum and systematic assumptions. This connects a possible underground signal to a concrete program for testing thermal electroweak dark matter at future colliders.

We present exact analytical solutions to the nonlinear relativistic Boltzmann equation for homogeneous, isotropic massless multi-component systems with non-isotropic scattering cross sections. For a two-component system, we identify three distinct classes of exact solutions, each corresponding to specific constraints among initial energy densities, particle number densities, and scattering cross sections. These solutions comprise the equilibrium state and two novel classes: a hybrid structure featuring a non-equilibrium Maxwell-Juttner distribution coupled with a nontrivial distribution; the former is unprecedented in kinetic theory, while the latter refers to nontrivial dynamics shared by both species, which is novel in the relativistic context.

We investigate how neutrino–dark matter (DM) interactions modify the flavor composition of high-energy neutrinos from active galactic nuclei (AGNs). Coherent forward scattering in a DM spike around the central supermassive black hole can generate a flavor-dependent potential, inducing flavor conversion as the neutrinos escape. We calculate the flavor composition at Earth for pion-decay and muon-damped sources and find substantial departures from vacuum-oscillation expectations. At neutrino energies around $100\,\mathrm{TeV}$, the matter potential begins to compete with vacuum oscillations when the coupling-weighted net DM number density reaches $|\epsilon_\alpha(n_\chi-n_{\bar\chi})|\sim10^{18}\,\mathrm{cm}^{-3}$. We compare our predictions with IceCube flavor triangle measurements under the illustrative assumption that the diffuse flux originates from AGNs with common neutrino-production and DM-spike properties. Under this assumption, when the DM-induced potential acts on the muon flavor and dominates the vacuum terms at production, the $p\gamma$ muon-damped predictions lie outside the 95% MESE contour. High-energy neutrino flavor measurements can therefore provide a novel probe of neutrino-DM interactions in astrophysical environments.

In strongly supercooled cosmological phase transitions, which generically lead to strong, observable gravitational-wave backgrounds, the scalar field typically transitions to a value well below the minimum of its potential. We study particle production caused by the subsequent evolution of the field. Because some modes feature temporarily tachyonic masses, they can be efficiently produced, and a significant fraction of the energy density released in the phase transition can get converted to particles rather than gradient energy. This has consequences for the shape and amplitude of the gravitational-wave spectrum caused by the interactions in bubbles and sources a new, high-frequency signal. Moreover, it affects the bubble expansion velocity and equation of state, which can facilitate the formation of primordial black holes.

Single-field models of inflection point inflation experience a phase of ultra-slow roll (USR), leading to amplified curvature perturbations. Recently, Lorenzoni et al. modified the scenario by adding a light spectator field, showing that it ruins USR by setting a floor for the first slow-roll parameter $\epsilon$. Mixing with isocurvature perturbations still amplifies the curvature power spectrum. We offer an alternative point of view, arguing that the inflaton still undergoes effective USR. The spectator lifts the potential by a constant amount, and the inflaton perturbations follow single-field dynamics in the lifted inflection point potential, decoupling from the spectator perturbations. Mode mixing only affects the power spectrum dip, making it milder. We demonstrate this effective single-field behavior numerically for example models. Our results offer a simple way to study the models' parameter dependence.

Longitudinal hyperon polarization is generated by velocity gradients at decoupling, but its quantitative connection to the evolving collision geometry has remained unclear. We analyze 48 Pb-Pb initial states with (3+1)-dimensional ideal hydrodynamics and the isothermal local-equilibrium spin prescription. The positive kinematic-shear contribution correlates with the freeze-out eccentricity $\epsilon_{2,\mathrm{fo}}$, whereas the magnitude of the negative kinematic-vorticity contribution depends jointly on elliptic flow $v_2$ and the eccentricity survival fraction $S_\epsilon=\epsilon_{2,\mathrm{fo}}/\epsilon_{2,\mathrm{init}}$. Their competition follows $R\simeq0.84(\epsilon_{2,\mathrm{fo}}/v_2)^{0.47}$, and their sum is described by $P_{z,s2}^{\mathrm{ILE}}\simeq0.0404v_2S_\epsilon [0.850(\epsilon_{2,\mathrm{fo}}/v_2)^{1/2}-1]$. This compact relation describes $87\%$ of the variation across the 48-state scan. After its coefficients were fixed, it describes $86\%$ of the variation across 12 newly calculated initial states, including four at the previously unsampled $b_0=0.685$. A proof-of-principle inversion using ALICE polarization data then returns freeze-out eccentricities inside the model fit domain. These results show that longitudinal polarization can constrain the spatial anisotropy remaining at decoupling, complementing the momentum-space information carried by elliptic flow.

The LUX-ZEPLIN experiment has reported one nuclear-recoil event at $248\pm23_{\rm stat}\pm23_{\rm sys}\,{\rm keV}$ in a $2.84\,{\rm tonne\text{-}year}$ exposure, with a local significance of $3.4\sigma$. Inelastic (endothermic) dark matter is a natural candidate: its kinematic threshold suppresses low-energy recoils and shifts the signal toward higher recoil energies. We perform a model-independent analysis of the LZ data using two sidebands, without specifying an ultraviolet completion, so our results apply broadly to inelastic dark matter with coherent spin-independent nuclear scattering. For each $(m_\chi,\delta)$ we compute $N_{\rm low}/N_{\rm sig}$ and $N_{\rm hi}/N_{\rm sig}$—predicted count ratios in the sidebands $[14,225)\,{\rm keV}$ and $(271,800]\,{\rm keV}$ relative to the signal region $[225,271]\,{\rm keV}$. The two ratios vary in opposite directions with $\delta$ and are simultaneously optimized at a unique splitting $\delta^\star$. For $m_\chi=1\,{\rm TeV}$, $\delta^\star=339\,{\rm keV}$ with a combined Poisson tension of $\approx1.9\sigma$; over $500\,{\rm GeV}$–$3\,{\rm TeV}$, the tension at $\delta^\star$ rises from $\lesssim1.3\sigma$ to $\approx2.5\sigma$. Additional suppression arises from the Helm form factor: $|F_{\rm Xe}^{\rm Helm}|^2\simeq3\times10^{-4}$ at $248\,{\rm keV}$, near its second diffraction zero. A dedicated LZ search over $271<E_R<800\,{\rm keV}$ would provide a decisive test of inelastic dark matter with $\delta\gtrsim330\,{\rm keV}$.

Astrophysical sources of ultra-high-energy cosmic rays (UHECRs) remain unidentified, and no nearby cosmic accelerators are established even for the highest-energy events. In addition, puzzling correlations of a fraction of UHECR flux with distant blazars were found by HiRes and, recently, Telescope Array experiments. Here we propose that dark matter can provide a mechanism to effectively transfer UHECRs from distant sources: dark-matter particles are boosted by UHECRs near the source and pass their momentum to baryons close to the observer. The probability of this relay is not negligible because of the growth of dark-matter-baryon cross section with energy. We demonstrate that the effect is observable for fermionic dark matter of mass $m_{\mathrm{DM}} \sim 25$ MeV and discuss possible observational signatures of this mechanism.

We propose that the dark matter (DM) is a pseudo-Dirac fermion with a mass of approximately $20-100$ GeV that couples inelastically to the Standard Model through a hadrophilic spin-1 mediator, $V$, the gauge boson of spontaneously broken baryon number. The two DM eigenstates, $\chi_{1}$ and $\chi_2$, acquire approximately equal abundances after thermal freeze-out and are depleted through the processes $\chi_1 \chi_1 \to VV$ and $\chi_2 \chi_2 \to VV$. Although the heavier state is unstable, for a mass splitting below the electron-positron threshold and sufficiently small mass mixing with the $Z$ boson, its lifetime can exceed the age of the universe, allowing both states to remain approximately equally abundant in the Galactic halo. For a thermal-relic annihilation cross section, this model can produce a signal that is consistent with the observed features of the longstanding Galactic Center Gamma-Ray Excess (GCE). If $\delta \sim 1000$ keV, the same parameter space that explains the GCE can also explain the LZ event through exothermic $\chi_2 \to \chi_1$ downscattering off xenon nuclei.

We investigate the potential of Higgs cascade decays to probe neutralino dark matter below the neutrino floor in the semi-constrained Next-to-Minimal Supersymmetric Standard Model with nonuniversal gaugino masses. We focus on lightest-neutralino masses of 65 to 100 GeV and study the process $pp\to H_2\to A_1A_1\to\gamma\gamma+\tilde{\chi}_1^0\tilde{\chi}_1^0$, where $H_1$ is the observed SM-like Higgs boson, $H_2$ is a heavier CP-even state, and $A_1$ is the lightest CP-odd state. The selected parameter region lies near the $A_1$ resonance, with $m_{A_1}>2m_{\tilde{\chi}_1^0}$, allowing both resonantly enhanced neutralino annihilation and invisible $A_1$ decays. After imposing theoretical and experimental constraints, we find surviving samples with cascade signal cross sections of approximately 0.16 fb at $\sqrt{s}=14~\mathrm{TeV}$ even when their relic-density-rescaled spin-independent scattering cross sections lie below the neutrino floor. A Monte Carlo analysis of a representative benchmark point yields an expected statistical significance of approximately $6.1\sigma$ at the high-luminosity LHC with an integrated luminosity of $3000~\mathrm{fb}^{-1}$, neglecting systematic uncertainties. These results highlight the potential of the diphoton plus missing transverse momentum channel as a complementary probe of neutralino dark matter.

The search for electroweak supersymmetric particles remains an important part of the LHC program since neutralinos and charginos with masses around a few hundred GeV are still compatible with the present constraints in compressed spectra. Run-2 searches for the “golden channel”, $pp\to\widetilde\chi_2^0\widetilde\chi_1^\pm\to\widetilde\chi_1^0 Z^{(*)}\widetilde\chi_1^0 W^{\pm(*)}$, have reported mild excesses in parts of the soft two- and three-lepton data, with the corresponding simplified-model interpretations emphasizing $m_{\widetilde\chi_2^0}\simeq m_{\widetilde\chi_1^\pm}\gtrsim200$~GeV and a neutralino mass difference near $20$~GeV. We study this configuration in the Minimal Supersymmetric Standard Model (MSSM) with the Generalized minimal Supergravity (GmSUGRA) boundary conditions, imposing the Higgs, flavor, collider, relic-density and direct-detection constraints relevant to the spectrum. For both signs of $\mu$, the solutions compatible with the Planck experiment contain an almost pure bino $\widetilde\chi_1^0$ with mass about $260$–$266$~GeV and a nearly degenerate wino-like $\widetilde\chi_2^0/\widetilde\chi_1^\pm$ pair near $280$~GeV. The resulting splitting, $\Delta m_{21}\simeq18.5$–$19.1$~GeV, lies in the mass-difference region probed by the ATLAS and CMS soft-lepton searches and places the $Z^{(*)}/W^{(*)}$ decays below the on-shell gauge-boson thresholds. The same compressed hierarchy keeps the wino states thermally populated during freeze-out, so bino-wino coannihilation yields a neutralino relic abundance consistent with the Planck experiment while the surviving solutions remain compatible with the direct-detection experimental bounds. Thus, the GmSUGRA boundary conditions provide a high-scale realization of the compressed bino-wino spectrum relevant to the LHC soft-lepton channel.

We compute universal scaling exponents and scaling functions for massless scalar field theories far from equilibrium. Using a large-$N$ expansion to next-to-leading order, we investigate the nonperturbative infrared behaviour associated with the transport of a) energy or b) effective particle number towards low frequencies $\omega$ and momenta $\bar p$. For massless dispersion $\omega = \bar{p}$, we determine the scaling form of the distribution function whose universal power-law tail $f_S(\bar p) \sim 1/\bar{p}^\kappa$ is found to be a) $\kappa = d+1$ and b) $\kappa = d$ in $d=3$ spatial dimensions. Our results establish that relativistic and nonrelativistic theories do not belong to the same universality class in this case, which opens up new applications to far-from-equilibrium phenomena in high-energy and (quantum) many-body physics with linear dispersions.

We construct the Super-Composite Higgs, a scenario designed to stabilize the Higgs mass and generate the flavor structure within a single dynamical framework. The basic idea is to combine supersymmetry and compositeness, where the Higgs mass is protected by supersymmetry and Yukawa couplings are generated through partial compositeness. This combination offers mutual advantages and ameliorates several drawbacks of each individual theory. The Super-Composite Higgs makes experimentally testable predictions across three different areas of fundamental physics. At the precision frontier, the electron EDM is predicted to be within reach of future experiments. At the observational cosmology frontier, measurable effects in CMB and large-scale structures are expected from an ultra-light gravitino. At the high-energy frontier, an upper bound on supersymmetric particle masses, derived from cosmological considerations, indicates that squarks should be lighter than about 10 TeV, which is within reach of the FCC-hh.

Motivated by the recent observation of the $B_c^*$ meson by the ATLAS Collaboration and its promising discovery potential at future high-luminosity colliders, we investigate the semileptonic decays $\bar{B}^*_{c} \to (P, V) \ell^- \bar{\nu}_{\ell}$ ($P=D$, $B_{d,s}$, $\eta_c(1S,\,2S,\,3S)$; $V=D^*$, $B^*_{d,s}$, $\psi(1S,\,2S,\,3S)$) in the Standard Model. Using the relevant form factors obtained in the self-consistent covariant light-front quark model, we present theoretical predictions for several physical observables, including the branching fraction, the ratios of branching fractions $R_{(L)}$, the longitudinal polarization fraction of the daughter vector meson, the $\tau$ lepton spin asymmetry and the forward-backward asymmetry. It is found that the branching fractions for the Cabibbo-favored $\bar{B}^*_{c}$ $\to$ $\bar{B}^*_{s} e^- \bar{\nu}_e$ and $\bar{B}^*_{s} \mu^- \bar{\nu}_\mu$ decays reach the order of ${\cal O}(10^{-6})$, which might be firstly observed at the future high-luminosity Large Hadron Collider.

A lowering of the post-inflation reheating temperature $T_{\rm RH}$ has attracted much attention as a means to facilitate obtaining the correct Dark Matter (DM) relic abundance. We take a relook at the paradigm under the assumption that the inflaton decay is essentially instantaneous, with the thermal bath coming into existence only at a relatively low temperature. We demonstrate that, contrary to the popular misconception, the relevant scale is not necessarily the DM mass itself, but the characteristic temperature at which the dominant DM production processes are thermally efficient. With $T_{\rm RH}$ setting the maximum temperature available for thermal production, and thereby determining the accessible stages of the production history, lowering $T_{\rm RH}$ tends to reduce the relic abundance. While this effect could, in principle, be offset by altering the couplings defining the theory, there exists a minimum $T_{\rm RH}$—determined by the mass spectrum—below which the relic abundance falls to minuscule levels, whether the mechanism be freeze-in or freeze-out.

We present a systematic study of semileptonic decays of heavy vector mesons within the Hard-Wall AdS/QCD framework. Semileptonic decays provide a clean environment for testing the Standard Model because the leptonic current is well understood, while the hadronic part is encoded in transition form factors that reflect non-perturbative QCD dynamics. The processes under consideration include: \( \psi \to D^{*-} ( D^{-} ) \ell^{+} {\nu}_{\ell} \), \( D^{*0} \to \pi^{-} \ell^{+} {\nu}_{\ell} \), \( D^{*+}_{s} \to K^{0} \ell^{+} {\nu}_{\ell} \), \( D^{*0} \to \rho^{-} \ell^{+} {\nu}_{\ell} \), \( B_c^{*+} \to B^{*0} \ell^{+} {\nu}_{\ell} \), \( B_c^{*+} \to \psi \,\ell^{+} {\nu}_{\ell} \), \( B^{*-} \to D^{*0} \ell^{-} \bar{\nu}_{\ell} \), \( B^{*0} \to D^{*+}(D^{+}) \ell^{-} \bar{\nu}_{\ell} \), \( B^{*0}_{s} \to D^{*+}_{s} (D^{+}_{s}) \ell^{-} \bar{\nu}_{\ell} \), \( \psi \to D^{*-}_{s}(D^{-}_{s}) \ell^{+} {\nu}_{\ell} \), \( D^{*0} \to K^{*-} (K^{-}) \ell^{+} {\nu}_{\ell} \), \( B_c^{*-} \to D^{*0} \ell^{-} \bar{\nu}_{\ell} \), \( \bar{B_{s}}^{*0} \to K^{*+} \ell^{-} \bar{\nu}_{\ell} \), and \( \bar{B}^{*0} \to \rho^{+} \ell^{-} \bar{\nu}_{\ell} \). These decays correspond to four different quark-level transitions: \(c\to d\), \(b\to c\), \(c\to s\), and \(b\to u\), allowing us to explore a broad range of flavor dynamics.\\ Using the Hard-Wall AdS/QCD model, we compute the relevant transition form factors as functions of the momentum transfer \(q^{2}\). The framework provides analytic expressions for meson wave functions and decay constants, which serve as inputs for the form-factor calculations. From these form factors, we evaluate the differential and integrated branching ratios for each decay mode. Where possible, we compare our predictions with results obtained from other non-perturbative approaches.

An inverse seesaw model for neutrino masses and mixing is proposed, based on the spontaneous breaking of a $D_4$ flavor symmetry. The model simultaneously accounts for the neutrino oscillation parameters, the baryon asymmetry of the Universe through TeV-scale leptogenesis, and makes predictions for charged-lepton flavor violation (cLFV) that are consistent with present experimental limits. A phenomenological analysis shows that the model is consistent with the observed neutrino oscillation data for both normal and inverted mass orderings. Successful leptogenesis is realized for the lightest pseudo-Dirac pair in the multi-TeV range. The predicted cLFV branching ratios lie well below experimental upper bounds, ensuring compatibility with existing constraints. These results establish the model as a viable framework that links low-energy neutrino observables to TeV-scale leptogenesis and cLFV phenomenology.

We investigate the effects of super-Gaussian pulse shapes on dynamically assisted pair production in spatially inhomogeneous electric fields with frequency chirping within the framework of the (1+1)-dimensional Dirac-Heisenberg-Wigner formalism. The analysis is carried out for both single-color fields and dynamically assisted two-color combined fields by varying the chirp parameter, super-Gaussian pulse shape, and the spatial scale of the external field. Our results are presented in terms of the reduced momentum distribution and the total particle yield, revealing that the interplay between pulse shaping, spatial inhomogeneity, frequency chirping, and dynamical assistance can significantly modify the pair-production dynamics. In particular, chirping substantially enhances the absolute pair-production yield and reshapes the momentum spectrum, with chirping of the weak component being particularly effective, while simultaneous chirping of both components produces the largest yields. The super-Gaussian order has a relatively modest influence on strong-field production, while increasing the flat-top character of the pulse enhances spectral structures and momentum redistribution in the weak and dynamically assisted regimes, particularly under chirping. Finally, we show that the relative phase between the two field components provides an additional control parameter, with its influence becoming more pronounced for larger spatial scales leading to significant changes in the momentum-space structure. Overall, our results provide a useful reference for optimal control of dynamically assisted pair production in space- and time-dependent electric fields within a prescribed range of field parameters.

Pulsar timing arrays (PTAs) have detected a nanohertz gravitational-wave background, often attributed to annihilating domain walls (DWs) or first-order phase transitions (FOPTs). Their reheating imprints fluctuations in the baryon-to-photon ratio. These so-called baryon isocurvature fluctuations $S_B$ survive until Big Bang Nucleosynthesis, whose yields depend nonlinearly on it. Modest $S_B$ fluctuations can therefore alleviate the current deuterium tension in parts of the PTA preferred regions and therefore strengthen their interpretation. Overabundant DWs and too strong FOPTs overproduce $D/H$ and are ruled out.

In this paper, it is shown that in spacetimes of maximal proper acceleration, there is a reduction of the mean lifetime of the muon. We consider several candidates for the maximal proper acceleration. For all of them, the induced corrections are small, but for the case when the maximal proper acceleration is identified with the Schwinger's acceleration, the effect is detectable in future muon collider facilities.

We investigate how the chiral anomaly influences the decomposition of nucleon spin between quark spin and orbital motion. We extend the chiral quark soliton model by including a flavor-singlet pseudoscalar field whose mass is generated by the chiral anomaly. Within this framework, we calculate the quark and antiquark helicity and orbital angular momentum distributions, accounting for the singlet field induced by the rotation of the soliton. We vary the anomaly-induced mass while keeping the remaining model parameters fixed to examine how the anomaly affects the spin decomposition. The induced field enhances the quark helicity contribution relative to the conventional pion-only model. Increasing the mass suppresses this enhancement and increases the orbital contribution, while the two contributions continue to account for the nucleon spin. This redistribution remains modest over the parameter values considered and does not qualitatively alter the spin decomposition of the conventional model.

We obtain nonperturbative asymptotic expansions of the electromagnetic form factors of the pi and rho mesons at large spacelike momentum transfer, Q^2->\infty. The calculation is based on a double integral representation in the invariant masses of the composite system. The model parameters are kept at the values fixed in the authors' earlier description of meson electroweak properties. We show that, in the limit of vanishing constituent-quark mass, with the constituent quarks taken to be pointlike, the asymptotic ratio of the longitudinally polarized rho-meson to pion form factors in the helicity basis is consistent with the prediction of perturbative QCD (pQCD) within the adopted parameter ranges.

We review Bayesian models for estimating the uncertainty induced by missing higher orders in perturbative predictions. These models return probability distributions, which have peculiar shapes typically very different from the Gaussian distribution often assumed in physics analysis. In this work, we are able to obtain smooth probability distributions with quasi-Gaussians shapes by suitably modifying the likelihood and the priors of the models.

The impact parameter and transverse charge densities provide spatially resolved information on hadron structure and probe the interplay between dynamical chiral symmetry breaking and SU(3)-flavor symmetry breaking. We investigate the valence-quark distributions of the pion and kaon using their unpolarized vector GPDs at nonzero skewness $\xi$ within the covariant Nambu–Jona-Lasinio model, with ultraviolet divergences regulated by the Schwinger proper-time scheme. Increasing $\xi$ shifts the distributions toward smaller $x$, reduces their central magnitude at $b_\perp=0$, and broadens their transverse profiles. These results provide insight into the spatial structure of the pion and kaon and offer stringent tests of nonperturbative QCD dynamics, with relevance to forthcoming measurements at Jefferson Lab and the Electron-Ion Collider.

The LUX-ZEPLIN (LZ) experiment recently reported a nuclear-recoil-like candidate at $E_R=248\pm23_{\rm stat}\pm23_{\rm sys}$ keV. We show that such an energetic recoil can arise from the elastic form factor of composite dark matter, without invoking an inelastic mass splitting or a boosted population. A neutral baryon of $N$ dark quarks can have a charge form factor that is suppressed at low momentum transfer but recovers at higher momentum transfer, providing a momentum-space band-pass filter. Modeling the form factor with one Gaussian per charged constituent species, we prove that two terms cannot produce a hard recoil spectrum and find that three yield too few events in the LZ signal window, while four suffice. A confining $SU(4)_D\times U(1)_D$ gauge theory provides a concrete realization through a neutral bosonic baryon made of four dark quarks. For a 200 GeV benchmark normalized to one accepted event, we predict approximately 1.5 true recoils beyond the current LZ region of interest. The form factor also produces diffraction nodes at fixed momentum transfers, placing them at recoil energies that scale as $1/m_A$ across target nuclei.

Thermal photons and dileptons provide complementary information on the temperature and collective expansion of matter created in relativistic heavy-ion collisions. Their combination has been proposed as an electromagnetic probe of radial flow: a comparatively flow-insensitive dilepton invariant-mass inverse slope is used to infer the photon inverse slope expected without transverse flow and compared with the observed photon slope. Here the physical basis and leading limitation of this construction are examined using a controlled expanding-fireball calculation. The dilepton and flow-free photon inverse slopes are tightly correlated because they respond similarly to changes of the underlying thermal scale, although the numerical relation depends on the spectral window and electromagnetic source. The flow-induced change of the photon inverse slope correlates more strongly with the photon-emission-weighted velocity component along the photon momentum than with a bulk-like radial-flow average. Prethermal source variations can bias the inferred flow-free photon reference and generate apparent flow even when the direct photon spectral-flow signal vanishes, while multiple photon and dilepton windows provide independent response patterns that can help diagnose this source ambiguity. These results clarify both what photon–dilepton radial-flow tomography measures and the source consistency required for its interpretation.

We investigate a long-lived scalar $S$ that triggers a strongly first-order electroweak phase transition (SFOEWPT) in the singlet scalar extension of standard model (SM). A sufficient small mixing angle between $S$ and the SM-like Higgs boson $h$ naturally leads to a long lifetime for $S$. We focus on the mass range $m_S>m_h/2$, where the dominant production channel at the LHC is the Higgs-mediated process $gg\to h^*\to SS$ with an off-shell $h$. By analyzing the finite-temperature effective potential, we identify the parameter space realizing an SFOEWPT and calculate the associated gravitational-wave spectra, finding that part of the parameter space can be probed by LISA. We further study the LHC sensitivity to the long-lived $S$ using the ATLAS detector and proposed far detectors, including ANUBIS, CODEX-b, FACET, FASER2, MoEDAL-MAPP1 and MAPP2, and MATHUSLA. The combined sensitivity of the main detector and far detectors, particularly ANUBIS and MATHUSLA, allows a large fraction of the SFOEWPT parameter space to be probed for $10^{-10}\leq \sin\theta\leq 10^{-5}$, with $m_S$ up to $250~\mathrm{GeV}$. For $\sin\theta\leq 10^{-11}$, however, the SFOEWPT parameter space becomes inaccessible to both the main detector and the far-detector searches.

The possibility of describing neutrino masses through a single multiplet of modular forms in a modular symmetric framework is reanalysed. The minimal model achieving this is Feruglio's model based on modular $A_4$ symmetry, which contains a chiral flavon triplet $\phi$, with all neutrino masses and mixing determined by a superfield triplet of modular forms $Y(\tau)$. We point out that, in local supersymmetry, these superfields by themselves allow an additional $R$-parity-violating contribution to neutrino masses originating from the Kähler potential of the model. The $R$ violation manifests through a bilinear term $\epsilon_i L_i H_u$ in the effective superpotential, with parameters $\epsilon_i$ determined in terms of $Y(\tau)$ and its derivatives. The Kähler potential also mixes neutrinos with the fermionic component of $\phi$, leading to seesaw neutrino masses when these fermions are massive. Two separate cases are analysed, with neutrinos obtaining mass through the Weinberg operator or through the $\phi$-induced seesaw. Unlike the original model, adding the $R$-violating contribution allows accurate reproduction of neutrino mixing angles and mass ratios for both the normal and inverted orderings in either case, with the Weinberg operator predicting a sum of neutrino masses close to the cosmological limit and the seesaw mechanism predicting ones comfortably below it.