11 August 2026

We construct a realization of sneutrino tribrid inflation within the $R$-symmetric flipped $SU(5)$ grand unified theory. A vector-like pair of matter multiplets, $10_V+\overline{10}_V$, provides a $D$-flat inflaton direction along the right-handed sneutrino component, with an additional $Z_2$ symmetry forbidding a direct inflaton mass term so that the leading inflationary interaction is a non-renormalizable Kähler-driven operator. Unlike previous studies, we treat the superpotential cutoff scale $M_s$ as independent of the reduced Planck mass, $m_P$, substantially enlarging the viable parameter space. Confronting the model with the ACT DR6/Planck determination $n_s=0.9734\pm0.0034$ and the $2σ$ bound on the running of the spectral index, we identify broad regions of viable parameter space in which the flipped $SU(5)$ symmetry-breaking scale can approach the conventional GUT scale, $M\simeq M_{\rm GUT}$, and the tensor-to-scalar ratio can reach observable values, $r\gtrsim10^{-3}$, within reach of forthcoming CMB $B$-mode experiments such as LiteBIRD and CMB-S4. We further study the post-inflationary dynamics, identifying the inflaton with the lightest right-handed sneutrino in a conventional type-I seesaw sector, whose out-of-equilibrium decay generates a lepton asymmetry that is converted into the observed baryon asymmetry via non-thermal leptogenesis and electroweak sphalerons, for a reheating temperature consistent with both successful leptogenesis and the gravitino constraint.

We investigate the implications of brane-inspired modifications of the evolutionary history of the early universe on the process of baryogenesis via leptogenesis. A modified cosmic history alters the evolution of the Boltzmann equations governing lepton asymmetry, providing the possibility of successful leptogenesis in regions of the parameter space inaccessible in the standard cosmological scenario. Furthermore, a modified cosmic history also alters the shape of an otherwise scale-invariant spectral energy density (SED) of primary gravitational waves (PGWs) produced during inflation. This establishes a novel yet indirect probe of high scale leptogenesis scenarios through the observation of the SED of PGWs via future observations. We consider two scenarios in this work with single and multiple epochs of stiff equation of state(s) after inflation and before the epoch of radiation domination. We identify the parameter space where successful leptogenesis is possible, along with the possible observability of the PGWs, hence providing an indirect window into this leptogenesis scenario through PGWs.

In this paper, we study the impact of different cross-section models in the measurement of the neutrino oscillation parameters in DUNE. In particular, for the quasi-elastic (QEL) region, we considered the Llewellyn-Smith formalism (LS) and the Hartree-Fock Continuum Random Phase Approximation (HF-CRPA) and for the resonance (RES) region, we consider the Rein-Sehgal (RS) and the Berger-Sehgal (BS) models, and compare our results with the DUNE cross-section tune (Valencia model for QEL and RS model for RES), which was considered in their technical design report. Our results show that while the DUNE tune is best for QEL, the best model for RES is BS. As the DUNE energy region is mainly dominated by RES, for the total cross-section, the HF-CRPA+BS model provides the best strength in the cross-section, whereas the DUNE tune is the weakest among all the configurations considered in our work. Regarding the neutrino mass ordering, CP violation and octant sensitivity, the HF-CRPA+BS model provides $(25- 30)$% improvement, and regarding the precision of the $θ_{23}$ and $Δm^2_{32}$, the same model provides $(15 - 20)$% improvement as compared to the DUNE tune.

Expanding the operational boundaries of radiation detection is imperative for contemporary particle physics, astrophysics, and cosmology. At this frontier, the direct detection of the Cosmic Neutrino Background (C$ν$B), the determination of the absolute neutrino mass scale, and the search for sub-GeV Light Dark Matter (LDM) necessitate detector architectures capable of sub-millielectronvolt (sub-meV) energy thresholds, exceptional absolute energy resolution, fast time response, and massive scalability. Current technologies confront an intrinsic limit---the ``impossible triangle''---wherein optimizing for sub-meV thresholds inherently compromises either macroscopic timing response or spatial scalability. Here, we introduce the Superconductor-Coupled Semiconductor Electron-Multiplying (SuperEM) detector, a fundamentally novel structural paradigm designed to bypass this limitation. The architecture couples the ultra-low energy threshold of a superconducting absorber with the intrinsic high-gain digitization of a strongly biased, high-density semiconductor P-N junction. Incident energy yields a proliferation of non-equilibrium quasiparticles, which are subsequently extracted via quantum tunneling across an ultra-thin Atomic Layer Deposition (ALD) insulating barrier. Building upon our prior empirical validation of deep-cryogenic avalanche mechanics, this manuscript establishes the fundamental theoretical feasibility and structural foundation of the complete device. Signal transport simulations confirm that an undoped interface coupled with a strong drift field enables highly efficient, nanosecond-scale transient electron drift, resolving completely within 35 ns. The SuperEM architecture thus constitutes a scalable, high-resolution, and fast time-response framework for next-generation C$ν$B and LDM observatories.

Searches for new physics in low-background experiments infer a non-negative signal strength from few events and often report an upper limit. Nominal frequentist coverage requires both a valid interval construction and an adequate data model. We study how controlled model departures affect lower- and upper-endpoint coverage for six interval procedures in an exact Poisson counting experiment, dark-matter recoil spectra, and a neutrinoless-double-beta-decay peak search. We introduce the Poisson--Fisher degeneracy index $\mathcal I_{\mathrm{PF}}(δν;\vartheta_0)=(β,γ)$, which maps a specified expected-count deformation, after projection onto the complete fitted tangent space, to $β$, the signed fitted signal shift in profiled standard-error units, and $γ$, the Poisson--Fisher norm of the unabsorbed residual. Locally, the sign of $β$ identifies the threatened endpoint, while larger $γ$ implies greater detectability by the saturated-Poisson goodness-of-fit test used here at a fixed $5\%$ type-I error rate. Across the studied deformations, positive signal-like bias degrades discovery-side coverage while making upper limits conservative; negative signal bias from overestimated signal efficiency can make the upper endpoint undercover. Calibration under the nominal simulator does not protect against misspecification of that simulator relative to the data-generating process. A plausible deformation with large $|β|$ and small $γ$ may therefore evade diagnosis and should be represented by a nuisance constrained with auxiliary information or included in a defensible envelope. In the exactly collinear constrained-nuisance benchmark, modelling the deformation restores coverage at the evaluated grid points, at a quantifiable cost in interval sensitivity.

Building on prior results [1], we introduce vector-valued modular resurgent series, whose components exhibit a single infinite tower of singularities in the Borel plane, trivial secondary resurgent series, and Stokes constants given by linear combinations of the coefficients of a vector of $L$-functions. We extend the paradigm of modular resurgence to this setting, emphasizing the role of the Stokes constants and the interplay between the associated vectors of $q$-series and Dirichlet series, and describing the resulting symmetry relating canonical pairs of vector-valued modular resurgent series. Moreover, we conjecture that certain vectors of $q$-series with modular resurgent asymptotics are vector-valued quantum modular forms and can be reconstructed via median resummation. Finally, we show that vectors of $q$-Pochhammer symbols, previously considered in [2], and Eichler integrals of vector-valued modular forms of weight $1/2$ and $3/2$ can be studied within the framework of vector-valued modular resurgence. While the first case amounts to a convenient repackaging of scalar modular resurgence, the second involves a non-trivial representation of the modular group and therefore illustrates the necessity of the vector-valued framework; we establish its modular resurgent structure in general, and work it out in full detail for the unary theta series, whose Eichler integrals are the false theta functions of quantum topology.

The first column of the lepton mixing matrix carries two independent magnitude conditions: the trimaximal norm $|U_{e1}|^2=2/3$ and the $μ$--$τ$ balance $|U_{\mu1}|=|U_{\tau1}|$. We parameterize their violation by $\varepsilon_1\equiv(3/2)|U_{e1}|^2-1$ and $\varepsilon_2\equiv3(|U_{\tau1}|^2-|U_{\mu1}|^2)$ and show that current data treat the two differently in central value: including the first JUNO measurement, $\varepsilon_1=+0.014\pm0.010$ is consistent with zero, while $\varepsilon_2=+0.29^{+0.07}_{-0.13}$ is large but disfavors zero at only $1.5σ$ on the global-fit profile likelihood, the driving phase being still poorly measured. This asymmetry selects the $π/12$ model. Its neutrino sector is TM$_1$ with the electron-row condition $|U_{e2}|/|U_{e3}|=2+\sqrt3$ that fixes $\sin^2θ_{13}=(2-\sqrt3)/12=0.02233$ and $\sin^2θ_{12}=0.31811$. A charged-lepton 2--3 rotation $R_{23}(θ_e,α)$ leaves the electron row exactly invariant and generates $\varepsilon_2=\sin2θ_e\cosα$. In an $S_4\times C_4\times C_3\times C_2$ realization, the rotation arises from a single additional flavon whose alignment forces $α=0$; a natural angle $θ_e\simeq2^\circ$ then reproduces the departure of $θ_{23}$ from maximal while pinning the CP phase to $δ=272^\circ\pm2^\circ$, near-maximal CP violation with $\varepsilon_2=-0.066$. The current $θ_{23}$--$δ$ measurements thereby become a sharp test: the predicted $δ$ sits $1.7σ$ from the present central value on the same profile likelihood, the predicted $\varepsilon_2$ has the opposite sign to the measured one, and the Hyper-Kamiokande design precision of $20^\circ$ on $δ$ resolves the question at $3σ$. The mass predictions are inherited unchanged, $Σm_ν=65.6$ meV and $m_{ββ}=5.4$ meV, at the current DESI bound in $Λ$CDM.

High-energy neutrino emission from the Galactic plane has been detected at a significance of $5.7σ$, with a prominent excess toward the inner Galaxy. We show that this excess can be naturally explained by the spatial distribution of Galactic neutrino sources. By combining $γ$-ray source catalogs spanning GeV-PeV energies and selecting candidate hadronic emitters, we construct ReGal-$γ$, a template of resolved Galactic $γ$-ray sources that may also produce high-energy neutrinos. Compared with models of Galactic diffuse emission, ReGal-$γ$ predicts a neutrino intensity that is more strongly concentrated toward the inner Galaxy. Combined with models of diffuse cosmic-ray emission and unresolved $γ$-ray sources, the template reproduces both the spectral energy distribution and the Galactic longitudinal count profile reported by IceCube without requiring additional renormalization of the emission models. We test this result using an independent $γ$-ray source template constructed from different catalogs and find that our conclusion is robust against uncertainties in source modeling. Future measurements of the energy-dependent longitudinal and latitudinal neutrino distributions will provide tighter constraints on these models and help determine the spatial distribution of Galactic neutrino sources.

Ultra-high-energy cosmic rays ($E_{\rm CR} \gtrsim 1$ EeV) are the highest-energy particles known, signaling extreme particle processes at work in the universe. However, many aspects of their nature remain largely unknown, even after more than a century of study. Very-high-energy ($E_ν\gtrsim 1$ PeV neutrinos associated with cosmic-ray interactions, both during the acceleration process and propagation, would provide new insight into these extreme particles, as we have seen at lower energies with the dawn of TeV neutrino astronomy. Nevertheless, only a handful of such neutrinos have been observed thus far. A space-based observatory dedicated to studying cosmic rays, neutrinos, and photons would provide an unprecedented platform for observations of these extreme-energy messengers.

The new era of multi-messenger astronomy requires the accurate and self-consistent derivation of the nuclear equation of state at high temperature. In the present work, we focused on the calculation of hot hybrid equations of state, studying the different evolution stages of a proto-neutron star with a quark matter core (proto-hybrid star). For the hadronic matter we used two distinct Skyrme effective interactions, while for quark matter the well-known vector MIT bag model was employed. To model the era of trapped neutrinos in the system we considered the global conservation of lepton fraction which resulted in an equation of state with an extended mixed phase. For periods following the neutrino diffusion phase of a proto-neutron star, the equations of state were modelled using both the Maxwell and the Gibbs construction depending on the assumption for either local or global electric-charge conservation. With the use of the derived hybrid models, we solved the Tolman-Oppenheimer-Volkov equations to describe the corresponding hybrid star configurations. Finally, we investigated how the structure of proto-hybrid stars evolves, using constant rest mass sequences. We found that regardless of whether electric-charge is globally or locally conserved, the earlier stages of a hybrid star's life may play a crucial role on the determination of its maximum possible gravitational mass in later stages.