We explore the possibility of directly detecting light, long-lived hidden sector particles at the IceCube neutrino telescope. Such particles frequently arise in nonminimal hidden sectors that couple to the Standard Model through portal operators. We consider two distinct scenarios. In the first scenario, which arises from a neutrino portal interaction, a hidden sector particle is produced inside the detector by the collision of an energetic neutrino with a nucleon, giving rise to a visible cascade. This new state then decays into a hidden sector daughter, which can naturally be long-lived. The eventual decay of the daughter particle back to Standard Model states gives rise to a second cascade inside the detector. This scenario therefore gives rise to a characteristic “double bang” signal arising from the two distinct cascades. In the second scenario, which arises from a hypercharge portal interaction, a hidden sector particle is produced outside the detector by the collision of an atmospheric muon with a nucleon. This new state promptly decays into a pair of hidden sector daughters that are long-lived. If both daughters decay into Standard Model states inside the detector, we again obtain a double bang signal from the two distinct cascades. We explore the reach of IceCube for these two scenarios and show that it has the potential to significantly improve the sensitivity to hidden sector models in the mass range from about 1 GeV to about 20 GeV.

We investigate the predictions for lepton number violating processes within the minimal theory of neutrino masses based on the spontaneous breaking of local lepton number. In this framework, the symmetry is broken at the low scale, leading to the existence of a viable dark matter candidate. The new fermions required for anomaly cancellation mediate lepton number violating processes at the one-loop level. We present a detailed calculation of the most relevant processes, including $\mu \to e\gamma$, $\mu \to 3e$, and $\mu \to e$ conversion in nuclei. The regions of parameter space excluded by current experimental bounds are identified, and we emphasize the interplay between collider observables and charged lepton flavor violating signatures as a key test of this theory of neutrino masses.

We present a unified model of quarks and leptons with modular $S_3$ flavor symmetry, where the two lightest family masses are naturally suppressed via a Pati-Salam version of the type I seesaw mechanism, mediated through heavier vectorlike fermions. Majorana neutrino masses are further suppressed through a double seesaw mechanism. The viable parameter space has a preferred range of the modulus field with $\mathrm{Im}(\tau )\sim 2$, leading to successful fermion masses and mixing. The prediction for neutrinoless double beta decay is partly within the reach of the nEXO experiment. In particular, the Dirac $CP$ violating neutrino oscillation phase is predicted to lie in the range ${\delta }_{CP}^{\nu }\sim 270°-360°$.

We investigate the Casimir effect for a massless scalar field confined between two parallel semitransparent mirrors in a vacuum modified by spontaneous Lorentz symmetry breaking. Using Green’s function techniques and a point-splitting evaluation of the stress-energy tensor, we compute the vacuum expectation value of the energy density $T^{00}$. After a suitable renormalization, the Casimir energy is obtained as the difference between the vacuum configurations with and without the mirrors. We derive closed-form expressions that generalize the conventional result by simultaneously incorporating the mirror transparency and the Lorentz-violating background. Our analysis shows that the effect of transparency and Lorentz violation consists of a multiplicative correction and an effective rescaling of the plate separation, thereby modifying the functional dependence of the energy on the distance. Beyond the formal derivation, we discuss possible physical realizations of this framework, emphasizing anisotropic media such as nematic liquid crystals (e.g., 5CB), where uniaxial dielectric properties could emulate the Lorentz-violating background. Numerical estimates for such systems illustrate the phenomenological impact of our results and open the possibility of constraining Lorentz-violating coefficients through precision Casimir measurements.

CP4 3HDM is a peculiar three-Higgs-doublet model in which a single symmetry leads to tight constraints on the scalar and Yukawa sectors. In this models, tree-level flavor-changing neutral couplings are unavoidable; however, as previously shown, their contributions to neutral meson oscillations can be suppressed. Here, we explore the remaining quark flavor violating effects, which give rise to the top quark decays to light scalars, including the 125 GeV Higgs boson $h_{\mathrm{SM}}$, as well as the magnitude of the $h_{\mathrm{SM}}t\overline{t}$ coupling. Utilizing the recently developed scanning procedure, in which observables are used as input, we narrow down the viable options to a unique CP4-invariant Yukawa sector capable of satisfying all meson oscillation and top quark constraints. We present benchmark models that feature neutral or charged Higgs bosons lighter than the top quark, and we look forward to testing them further at the LHC and through flavor physics observables.

Velocity-independent ($s$-wave) annihilation of thermal dark matter is ruled out by CMB data for masses below $\sim 10\mathrm{GeV}$, effectively ruling out the possibility of indirectly detecting it in this mass range. We demonstrate in a model-independent framework that Breit-Wigner effects from very narrow resonances can circumvent CMB constraints, thereby reviving the potential to detect $s$-wave DM annihilation in the present Universe. The density of resonant $s$-wave dark matter continues to evolve long after chemical decoupling, leading to a scenario we refer to as belated freeze-out, where kinetic decoupling plays a significant role in determining the relic density.

We explore the effects of low-scale cosmological first-order phase transitions (PTs) on big bang nucleosynthesis (BBN) and cosmic microwave background (CMB) anisotropies and distortions. We examine two scenarios: the PT energy acts as additional background energy, modifying the expansion history; and serves as energy injection into the baryon-photon fluid, generating CMB spectral distortions while having a negligible effect on the expansion history. Our analysis reveals that the CMB spectrum from the Planck 2018 dataset imposes stringent constraints on sub-MeV-scale PTs, while sub-keV-scale PTs can induce significant CMB distortions. Consequently, BBN and CMB observables serve as complementary tools to constrain PT parameters, alongside gravitational wave detections.

We propose to investigate the production of a light scalar boson $\varphi$ in low-energy proton-nucleus interactions using the 3.5 MV accelerator of the Bellotti Ion Beam Facility, located in the underground Gran Sasso National Laboratory. Nuclear reactions induced by a few-MeV proton beam on suitable target materials can act as a controlled source of $\varphi$ particles. Owing to the deep-underground location, the facility benefits from substantial cosmic-ray shielding, enabling searches for rare processes with minimal background. The produced $\varphi$ particles will be sought with large-volume, low-background detectors already operating or currently under construction at the Gran Sasso National Laboratory. This approach combines a tunable accelerator-based production mechanism with the exceptional sensitivity of underground rare-event searches, offering a novel avenue to probe light scalar bosons beyond the Standard Model.

We present a composite QCD axion model where the Peccei-Quinn symmetry emerges as a high-quality, accidental symmetry. The axion potential is only modified by eight-fermion, dimension-12 operators, which if present at the Planck scale, allow for axion dark matter from misalignment while solving the strong $CP$ problem. The model is an $\mathrm{SU}(N_c)$ gauge theory with ten flavors where the Pati-Salam unified subgroup $\mathrm{SO}(6)\times \mathrm{SO}(4)\subset \mathrm{SU}(10{)}_L$ and $\mathrm{Sp}(10)\subset \mathrm{SU}(10{)}_R$ are weakly gauged. The dynamics breaks $\mathrm{SU}(10{)}_L\times \mathrm{SU}(10{)}_R\to \mathrm{SU}(10{)}_V$ and the weakly gauged groups to $\mathrm{U}(3)\times \mathrm{U}(2)\supset \mathrm{SU}(3{)}_c\times \mathrm{SU}(2{)}_L\times \mathrm{U}(1{)}_Y$, with the QCD axion identified as one of the Nambu-Goldstone bosons. This axion has a relatively large coupling to photons while a residual ${\overline{\theta }}_{\mathrm{eff}}$ may be just below the current limit on the neutron electric dipole moment. If the dimension-12 operators are present near the grand unified theory scale, they can cause domain wall networks to decay, allowing for axion dark matter even for the postinflationary scenario.

Neutrinos that are elastically scattered off atomic electrons provide a unique opportunity to investigate the standard model (SM) and beyond SM physics. In this work, we explore the new physics effects of neutrino electromagnetic properties through elastic neutrino-electron scattering using solar neutrinos at the low-energy range of PandaX-4T and XENONnT experiments. The properties of interest include the neutrino magnetic moment, millicharge, and charge radius, all of which are natural consequences of nonzero neutrino masses. We investigate their effects by incorporating each property into the SM framework, given the measured solar neutrino flux. By analyzing the latest Run0 and Run1 datasets from the PandaX-4T experiment, together with recent results from XENONnT, we derive new constraints on each electromagnetic property of neutrino. We present both flavor-independent results, obtained using a common parameter for all three neutrino flavors, and flavor-dependent results, derived by marginalizing over the three neutrino flavor components. Bounds we obtained are comparable or improved compared to those reported in the previous studies.

This study employs the Faddeev formalism in configuration space to investigate the ${\mathrm{\Omega }}_{3c}NN$ cluster containing a triply charmed Omega baryon (${\mathrm{\Omega }}_{3c}$). Using the recently reported HAL QCD $S$-wave ${\mathrm{\Omega }}_{3c}N$ potentials in the ${}^3{S}_1$ and ${}^5{S}_2$ channels, together with the MT-I–III nucleon-nucleon potential and neglecting the Coulomb force, we find no bound state for the ${\mathrm{\Omega }}_{3c}np$ system. We predict near-threshold resonances in the $J^{\pi }=5/2^{+}$ (maximal total spin) and $J^{\pi }=1/2^{+}$ (minimal total spin) states, with resonance energies of 1.1 MeV below and 0.0 MeV at the three-body breakup threshold, respectively, at Euclidean time $t/a=16$. A similar analysis of the ${\mathrm{\Omega }}_{3c}{\mathrm{\Omega }}_{3c}N$ system likewise reveals no bound states, though a possible resonance is indicated.

We investigate the $K^{-}p\to \gamma \mathrm{\Sigma }$ reaction using an effective Lagrangian approach within an isobar model framework. The model includes contributions from $s$-channel hyperon and hyperon resonance, $t$-channel $K$ and $K^{*}$, $u$-channel proton and $\mathrm{\Delta }(1232)$ exchanges, and a phenomenological contact term. Our analysis focuses on the roles of various $\mathrm{\Lambda }$ resonances. The results indicate that the $\mathrm{\Lambda }(1600)$ resonance is crucial for describing the experimental data at lower energies. At higher energies, the inclusion of either the $\mathrm{\Lambda }(1670)$ or the $\mathrm{\Lambda }(1690)$ resonance significantly improves the agreement with data. However, the current data are insufficient to distinguish between these two scenarios. We suggest that future measurements at higher beam energies and the measurement of the $\mathrm{\Sigma }$ polarization are needed to identify the roles of the $\mathrm{\Lambda }(1670)$ and $\mathrm{\Lambda }(1690)$ resonances.

In this paper we carefully assess the theory prediction for $R(s)$ below charm threshold, $R_{uds}$, and address tensions with the existing data, notably with the 2021 BES-III results. We analyze the uncertainty of the perturbative quantum chromodynamics description in the light of renormalons making use of the large-${\beta }_0$ limit and the renormalon-free gluon-condensate scheme. We provide a reliable estimate of the duality violation contributions; we show they are sizable up to 2.5 GeV and improve the agreement between theory and data, but are negligible for higher energies. We then combine the available experimental data for $R_{uds}$ and find the datasets to be mutually compatible. Finally, we compare theory and data, both locally and in their contributions to the anomalous magnetic moment of the muon. Theory is compatible with the combined data but discrepancies with the BES-III data reach more than $3\sigma$.

We investigate the impact of an external magnetic field on the vector charmonium system within the framework of Hilbert moment QCD sum rules. By incorporating magnetic corrections to the perturbative contributions of the QCD sector, we analyze the behavior of the hadronic parameters of the $J/\psi$ resonance—namely, its continuum threshold $s_0$, decay constant $f_V$, width ${\mathrm{\Gamma }}_V$, and its mass $M_V$, as functions of the magnetic field strength. Our results show that $s_0$ and $f_V$ increase monotonically, while ${\mathrm{\Gamma }}_V$ decreases significantly and $M_V$ remains essentially constant. These behaviors indicate a strengthening of the hadronic state in the presence of a magnetic field, consistent with the phenomenon of magnetic catalysis. Although magnetic catalysis has traditionally been associated with light-quark systems via chiral symmetry breaking, our results demonstrate that similar effects persist in the heavy-quark sector, despite the absence of chiral dynamics.

In the quantum chromodynamics (QCD) vacuum, the nucleon form factors receive contributions from the underlying ensemble of topological pseudoparticles, which are sensitive to a finite vacuum angle $\theta$. We use this observation to derive a novel relationship between the Pauli and electric dipole form factors, for light quark flavors. This relationship allows for an explicit derivation of the proton and neutron electric dipole moments induced by a small $CP$ violating $\theta$ angle, in terms of the vacuum topological susceptibility times pertinent magnetic moments. The results compare well with some recent lattice estimates.

The recently observed $K(1690)$ has been identified as a supernumerary pseudoscalar resonance signal in the strange-meson spectrum predicted by quark model calculations. It is the best candidate of a strange cryptoexotic state. In this work, we systematically study the hadron masses of $ud\overline{d}\overline{s}$ tetraquark states with $J^P=0^{-}$ in the method of QCD sum rules. For ten interpolating currents, we calculate the correlation functions up to dimension-8 nonperturbative condensates. To calculate the trigluon condensate, we comprehensively consider the contributions from different operators with and without covariant derivatives. The infrared safety can be guaranteed for the completely calculated trigluon condensate by properly addressing the IR divergences in Feynman diagrams. It is demonstrated that the trigluon condensate provides significant contributions to the sum-rule analyses in these light tetraquark systems. Our results support the interpretation of $K(1690)$ resonance to be a pseudoscalar $ud\overline{d}\overline{s}$ tetraquark state.

We evaluate the thermal photon emission rate from a chirally asymmetric quark gluon plasma using the hard thermal loop approximation. The quasiparticle and plasmino modes prevalent at finite temperature split into $L$ and $R$-modes in the presence of chiral imbalance and are found to disperse differently acquiring different thermal masses. The soft contribution to the thermal photon emission rate obtained from the retarded self-energy is found to contain additional terms proportional to the square of the quark and chiral chemical potentials which is found to cause an enhancement to thermal photon emission in the presence of chiral imbalance.

Particle production in hadronic collisions can be studied in the low-momentum (soft) and high-momentum (hard) transfer regimes. While the latter can be well understood within perturbative QCD, the former contains nonperturbative effects which cannot be calculated from first principles. There is also an intermediate regime called semihard, in which the momentum transfer runs typically from 1 to 10 GeV. As the hadron-hadron collision energy increases, we expect to see a relative growth of the number of semihard events. It has been conjectured that this growth would be the cause of some changes observed in the multiplicity distributions measured in proton-proton collisions. In this paper we revisit the separation between soft and semihard events using the formalism of $k_T$ factorization. The separation is implemented through the introduction of a scale that is the cutoff $\mathrm{\Lambda }$ in the transverse momentum of the produced gluon and allows us to compute the average number of particles produced in each regime. These numbers are used as input in the double negative binomial fit of data, from which we can extract correlations between the fraction of semihard events and the violation of Koba-Nielsen-Olsen scaling.

We further scrutinize the evidence for a recently suggested pseudoscalar particle, the electroweak ${\eta }_{\mathrm{w}}$ meson. Its existence is demanded by matching the removal of the weak vacuum angle ${\theta }_{\mathrm{w}}$ by the anomalous $B+L$ symmetry with a massive pole in the topological susceptibility of the vacuum. We specifically focus on the possibility of the emergence of ${\eta }_{\mathrm{w}}$ as a collective excitation of the phase of the condensate of the ’t Hooft fermion determinant, generated by the electroweak instantons, which breaks the $B+L$ symmetry spontaneously. We argue that the generation of the ’t Hooft vertex is in one-to-one correspondence with its nonzero vacuum expectation value which is cutoff insensitive. We outline certain puzzles about the nature of the emergent ${\eta }_{\mathrm{w}}$ which require further investigation.

We recently measured the branching fraction of the $B^{+}\to K^{+}\nu \overline{\nu }$ decay using $362{\mathrm{fb}}^{-1}$ of on-resonance $e^{+}{e}^{-}$ collision data under the assumption of Standard Model kinematics, providing the first evidence for this decay. To facilitate future reinterpretations and maximize the scientific impact of this measurement, we publicly release the full analysis likelihood along with all necessary material required for reinterpretation under arbitrary theoretical models sensitive to this measurement. In this work, we demonstrate how the measurement can be reinterpreted within the framework of the weak effective theory. Using a kinematic reweighting technique in combination with the published likelihood, we derive marginal posterior distributions for the Wilson coefficients, construct credible intervals, and assess the goodness of fit to the Belle II data. For the weak effective theory Wilson coefficients, the posterior mode of the magnitudes $|C_{\mathrm{VL}}+C_{\mathrm{VR}}|$, $|C_{\mathrm{SL}}+C_{\mathrm{SR}}|$, and $|C_{\mathrm{TL}}|$ corresponds to the point (11.3, 0.0, 8.2). The respective 95% credible intervals are [1.9, 16.2], [0.0, 15.4], and [0.0, 11.2].