We investigate density fluctuations and scalar-induced gravitational waves (GWs) arising from the production of long-lived solitons and oscillons, which can dominate the early Universe and drive reheating prior to the standard radiation-dominated era. Curvature perturbations are generated not only by the Poisson distribution of these solitons/oscillons but are also amplified during the early matter-dominated phase when the solitons/oscillons dominate. Scalar-induced GWs with characteristic energy spectra emerge from these amplified curvature perturbations, particularly at the sudden transition from matter domination to radiation domination. We analyze this scenario and its GW predictions in detail, focusing on the impact of the initial energy fraction, the lifetime, and the average separation of these solitons/oscillons. This provides a wealth of potential observational targets for various GW detectors. Furthermore, for inflation and preheating models that produce oscillons with large separations, we derive new constraints on these models based on the upper bounds on the effective number of relativistic degrees of freedom, as anticipated from future cosmic microwave background and large-scale structure observations.

A new integration method drastically improves the efficiency of the dark matter direct detection calculation. In this work I introduce a complete, orthogonal basis of spherical wavelet-harmonic functions, designed for the new vector space integration method. This factorizes the numeric calculation into a “vector” that depends only on the astrophysical velocity distribution; a second vector, depending only on the detector form factor; and a scattering matrix defined on the basis functions, which depends on the details of the dark matter (DM) particle model (e.g. its mass). For common spin-independent DM–Standard Model interactions, this scattering matrix can be evaluated analytically in the wavelet-harmonic basis. This factorization is particularly helpful for the more complicated analyses that have become necessary in recent years, especially those involving anisotropic detector materials or more realistic models of the local DM velocity distribution. With the new method, analyses studying large numbers of detector orientations and DM particle models can be performed more than 10 million times faster. This paper derives several analytic results for the spherical wavelets, including an extrapolation in the space of wavelet coefficients, and a generalization of the vector space method to a much broader class of linear functional integrals. Both results are highly relevant outside the field of DM direct detection.

The so-called metastability bound on the Higgs mass suggests that the smallness of the Higgs mass may be a by-product of the metastability of the electroweak vacuum. A significantly strong bound requires new physics capable of lowering the scale where the Higgs quartic coupling turns negative through renormalization group effects, without destabilizing the electroweak vacuum entirely. We analyze in this context the low-scale Majoron model of neutrino masses, which automatically contains two key elements for a viable scenario: heavy fermions to lower the instability scale and a extended scalar sector to stabilize the potential and achieve realistic lifetimes for the electroweak vacuum. We show how the metastability bound can be generalized to theories with multiple scalars and present an efficient way of calculating the tunneling rate in such potentials. We also demonstrate that FCC will probe regions of the parameter space relevant for metastability: large regions of the fermionic sector at FCC-ee and some reach to the scalar sector at FCC-hh.

We use a novel real-time formulation of the functional renormalization group (FRG) for dynamical systems with reversible mode couplings to study model H, the conjectured dynamic universality class of the quantum chromodynamics (QCD) critical point. We emphasize the structural similarities with model G, conjectured to be the dynamic universality class of the chiral phase transition in the limit of two massless quark flavors. Importantly, our formulation of the real-time FRG preserves all relevant symmetries throughout the FRG flow which, e.g., guarantees the nonrenormalization of the reversible mode couplings, as but one exact result. We derive nonperturbative RG flow equations for the kinetic coefficients of both, model G and H, in parallel, and discuss commonalities and differences in the resulting fixed-point structure and dynamic critical exponents, such as weak-scaling relations which hold in either case versus the characteristic strong scaling of model G which is absent in model H.

We present and discuss the release of novel sets of collinear, variable-flavor-number-scheme fragmentation functions for axial-vector, fully heavy $T_{4c}(1^{+-})$ and $T_{4b}(1^{+-})$ tetraquarks. Working within the single-parton approximation at leading power and employing nonrelativistic QCD factorization adapted for tetraquark Fock states, we model the initial-scale fragmentation input using a recent calculation for the constituent heavy-quark channel. Standard Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution is then applied, ensuring consistent implementation of evolution thresholds. To support phenomenology, we investigate $\mathrm{NLL}/{\mathrm{NLO}}^{+}$ rates for tetraquark-jet systems at the High-Luminosity LHC and Future Circular Collider from (sym)jethad. This study further integrates exotic matter explorations with precision QCD calculations.

We present a systematic diagrammatic investigation of the classical limit of observables computed from scattering amplitudes in quantum field theory through the Kosower-Maybee-O’Connell formalism, motivated by the study of gravitational waves from black hole binaries. We achieve the manifest cancellation of divergences in the $\hslash \to 0$ limit at the integrand level beyond one loop by employing the Schwinger parametrization to rewrite both cut and uncut propagators in a worldlinelike representation before they are combined. The resulting finite classical integrand takes the same form as the counterpart in the worldline formalisms such as post-Minkowskian effective field theory and worldline quantum field theory, and in fact exactly coincides with the latter in various examples, showing explicitly the equivalence between scattering amplitude and worldline formalisms. The classical causality flow, as expressed by the retarded propagator prescription, appears as an emergent feature. Examples are presented for impulse observables in electrodynamics and a scalar model at two loops, as well as certain subclasses of diagrams to higher orders and all orders.

We continue analytical study of the meson mass spectrum in the large-$N_c$ two-dimensional QCD, known as the ’t Hooft model, by addressing the most general case of quarks with unequal masses. Based on our previous work, we develop nonperturbative methods to compute spectral sums and systematically derive large-$n$ WKB expansion of the spectrum. Furthermore, we examine the behavior of these results in various asymptotic regimes, including the chiral, heavy quark, and heavy-light limits, and establish a precise coincidence with known analytical and numerical results obtained through alternative approaches.

Adaptive mesh refinement efficiently facilitates the computation of gravitational waveforms in numerical relativity. However, determining precisely when, where, and to what extent to refine when solving the Einstein equations poses challenges; several ad hoc refinement criteria have been explored in the literature. This work introduces an optimized resolution baseline derived in situ from the inspiral trajectory (ORBIT). This method uses the binary’s orbital frequency as a proxy for anticipated gravitational waves to dynamically refine the grid, satisfying the Nyquist frequency requirements on grid resolution up to a specified spin-weighted spherical harmonic order. ORBIT sustains propagation of gravitational waves while avoiding the more costly alternative of maintaining high resolution across an entire simulation—both spatially and temporally. We find that enabling ORBIT decreases waveform noise by an order of magnitude and better resolves high-order wave amplitudes through merger. Combined with WAMR and other improvements, updates to Dendro-GR decrease waveform noise, decrease constraint violations, and boost refinement efficiency each by factors of $\mathcal{O}(100)$, while reducing computational cost by a factor of 4. ORBIT and other recent improvements to Dendro-GR begin to prepare us for gravitational wave science with next-generation detectors.

Radio-to-$\gamma$-ray signals, recently found narrowly confined near the characteristic $2.4R_{500}$ scaled radii of galaxy clusters and groups, have been associated with their virial (structure-formation accretion) shocks based on spectro-spatial characteristics. By stacking high-latitude Global Magneto-Ionic Medium Survey radio data around galaxy clusters from the Metacatalog of x-ray Detected Clusters of galaxies, we identify ($3\sigma –4\sigma$) excess radially polarized emission at the exact same scaled radius, providing directional support, and indicating tangential magnetic fields induced by the shocked inflow. The results suggest a strong mass dependence, a flat energy spectrum, and a high polarization fraction, consistent with synchrotron emission from electrons accelerated by strong virial shocks. The narrow radial range of such stacked virial-shock signals suggests that although the shocks are theorized to have diverse, irregular morphologies, they share similar $\sim 2.4R_{500}$ minimal radii.

The detection of a gravitational wave background in the nanohertz frequency range from pulsar timing array (PTA) observations offers new insights into evolution of the early Universe. In this work we analyze gravitational wave data from PPTA, EPTA, and NANOGrav, as arising from a supercooled first-order phase transition within a hidden sector, characterized by a broken $U(1{)}_X$ gauge symmetry. Several previous works have discussed challenges in producing observable PTA signal from supercooled phases transitions. We discuss these challenges and show how they are overcome by inclusion in part of the proper thermal history of the hidden and the visible sectors. The analysis of this work demonstrates that thermal histories of hidden and visible sectors profoundly influence the gravitational wave power spectrum, an aspect not previously explored in the literature. Further, the analysis of this work suggests that supercooled phase transitions not only align with the pulsar timing array observations but also show promise for gravitational wave detection by future gravitational wave detectors. Our analysis shows that the dominant contribution to the gravitational wave power spectrum for PTA signal comes from bubble collision while the sound wave and turbulence contributions are highly suppressed. It is also found that all of the PTA events are of detonation type while deflagration and hybrid events are absent. The analysis presented in this work provides a robust framework for further investigations on the origin of gravitational wave power spectrum in the early Universe and for their experimental observation in the future.

Millisecond pulsars, representing the older neutron star population, are believed to have undergone a prolonged period of dark matter accumulation, resulting in a higher dark matter content. Their extreme rotation makes them unique laboratories for studying rapidly rotating neutron stars admixed with dark matter. In this work, we model uniformly rotating neutron stars with a dark matter component that rotates independently from the baryon matter, allowing for the investigation of both corotating and counterrotating scenarios. We examine the impact of dark matter rotation on the macroscopic properties of neutron stars, including the mass-radius relation, the mass-shedding Keplerian limit, and moments of inertia, for various dark matter particle masses and total fractions, considering both core and halo distributions. Our findings provide a more comprehensive understanding of how dark matter influences the equilibrium properties of rotating neutron stars, offering new insights into the astrophysical implications of self-interacting dark matter.

There has been growing evidence that mu and tau neutrinos are noticeably different due to the emergence of muons in core-collapse supernovae (CCSNe) and binary neutron star mergers (BNSMs). Recent theoretical studies also suggest that all flavors of neutrinos and antineutrinos inevitably experience some flavor mixing instabilities including fast neutrino flavor conversions (FFC), which corresponds to one of the collective neutrino oscillations powered by neutrino self-interactions. This represents a need for quantum kinetic treatment in the numerical modeling of neutrino dynamics, which is, however, a formidable computational challenge. In this paper, we present an approximate method to predict asymptotic states of FFC without solving a quantum kinetic equation under a three-flavor framework, in which mu and tau neutrino distributions are not necessarily identical to each other. The approximate method is developed based on a Bhatnagar-Gross-Krook (BGK) relaxation time prescription, capable of capturing essential features of mixing competitions among three different flavor-coherent states. Our proposed scheme is computationally inexpensive and easy to implement in any classical neutrino transport scheme.

We revisit the predictions of the nested leaky box model in detail, in terms of both primary cosmic-ray spectra, spectra of stable and unstable nuclei, and antimatter production (positrons and antiprotons). We conclude that the model is in direct conflict with several observational facts and at least in its vanilla version should be considered as ruled out by current data. We also speculate on some possibly interesting implications of the idea that at least a fraction of Galactic grammage may not be accumulated in the journey of cosmic rays in the interstellar medium but rather inside the sources or in regions around them. These speculations will become increasingly more relevant with the higher precision data becoming available at high energies.

High-energy physics simulations traditionally rely on classical Monte Carlo methods to model complex particle interactions, often incurring significant computational costs. In this paper, we introduce a novel quantum-enhanced simulation framework that integrates discrete-time quantum walks with quantum amplitude estimation to model photon interaction cross sections. By mapping the probabilistic transport process of 10 MeV photons in a water medium onto a quantum circuit and focusing on Compton scattering as the dominant attenuation mechanism, we demonstrate that our approach reproduces classical probability distributions with high fidelity. Simulation results obtained via the IBM Qiskit quantum simulator reveal a quadratic speedup in amplitude estimation compared to conventional Monte Carlo methods. Our framework not only validates the feasibility of employing quantum algorithms for high-energy physics simulations but also offers a scalable pathway toward incorporating multiple interaction channels and secondary particle production. These findings underscore the potential of quantum-enhanced methods to overcome the computational bottlenecks inherent in large-scale particle physics simulations.

We discuss leptogenesis in a Majoron model extended by a right-handed $SU(2{)}_L$ triplet fermion. We study several different parameter assignments and find that the interactions of neutrinos with the new particles in the Majoron plus triplet model can significantly alter the way leptogenesis proceeds. We show that for large parts of the considered parameter space, it is essential to solve the set of coupled Boltzmann equations for the evolution of the neutrinos and the additional particles rather than solving the Boltzmann equations for the neutrino evolution only.

We propose a novel method to determine the strong coupling of quantum chromodynamics (QCD) and fix its running behavior at all scales by using the Bjorken sum rules (BSR). The BSR defines an effective coupling ${\alpha }_s^{g_1}(Q)$ which includes the nonperturbative higher-twist corrections and perturbative QCD (pQCD) corrections to the leading-twist part. For the leading-twist part of ${\alpha }_s^{g_1}(Q)$, we adopt the infinite-order scale-setting procedure of the principle of maximum conformality (${\mathrm{PMC}}_{\infty }$) to deal with its pQCD corrections, which reveals the intrinsic conformality of the series and eliminates conventional renormalization scheme-and-scale ambiguities. Using the ${\mathrm{PMC}}_{\infty }$ approach, we not only eliminate the first kind of residual scale dependence due to uncalculated higher-order terms, but also resolve the previous “self-consistency problem.” The light-front holographic QCD model is used for ${\alpha }_s^{g_1}(Q)$ in the infrared region, which also reveals a conformal behavior at $Q\to 0$. As a combination, we obtain a precise ${\alpha }_s^{g_1}(Q)$ at all scales, which matches well with the known experimental data with $p$-value $\sim 98\%$, and determines the strong coupling constant at the scale $M_Z$, ${\alpha }_s(M_Z)=0.1220_{-0.0012}^{+0.0011}(\mathrm{\Delta }\kappa {)}_{+0.0007}^{-0.0046}(\mathrm{the}.)$, where the first error comes from $\mathrm{\Delta }\kappa$ of LFHQCD model and the second error is from the second kind of residual scale dependence.

In this paper, we consider hard-wall anti–de Sitter/quantum chromodynamics (AdS/QCD) models extended by a string-theory inspired Chern-Simons action in terms of a superconnection involving a bifundamental scalar field which corresponds to the open-string tachyon of brane-antibrane configurations and which is naturally identified with the holographic dual of the quark condensate in chiral symmetry breaking. This realizes both the axial and chiral anomalies of QCD with a Witten-Veneziano mechanism for the ${\eta }^{\prime }$ mass in addition to current quark masses, but somewhat differently than in the Katz-Schwartz AdS/QCD model used previously by us to evaluate pseudoscalar and axial vector transition form factors and their contribution to the hadronic light-by-light (HLBL) piece of the muon $g-2$. Compared to the Katz-Schwartz model, we obtain a significantly more realistic description of axial-vector mesons with regard to $f_1-f_1^{\prime }$ mixing and equivalent photon rates. Moreover, predictions of the $f_1\to e^{+}{e}^{-}$ branching ratios are found to be in line with a recent phenomenological study. However, pseudoscalar transition form factors compare less well with experiment; in particular the ${\pi }^0$ transition form factor turns out to be overestimated at moderate nonzero virtuality. For the combined HLBL contribution to the muon $g-2$ from the towers of axial vector mesons and excited pseudoscalars we obtain, however, a result very close to that of the Katz-Schwartz model.

We report a study of the inelasticity distribution in the scattering of neutrinos of energy 80–560 GeV off nucleons. Using atmospheric muon neutrinos detected in IceCube’s sub-array DeepCore during 2012–2021, we fit the observed inelasticity in the data to a parameterized expectation and extract the values that describe it best. Finally, we compare the results to predictions from various combinations of perturbative QCD calculations and atmospheric neutrino flux models.