We report on the first loosely coherent search for continuous gravitational waves from neutron stars in binary systems. We searched $\approx 0.01\mathrm{sr}$ in the Orion spur, a high stellar density region close to Earth. We covered gravitational wave frequencies from 100 to 700 Hz and frequency derivatives in the range $\pm {10}^{-11}\mathrm{Hz}/\mathrm{s}$. An atlas of results from the search is made publicly available. A follow-up was performed, on a subset of the released results, which found no outliers.

We consider the production of a $Z$ boson decaying to leptons in association with a bottom-quark pair in hadronic collisions. For the first time, we compute predictions at next-to-next-to-leading order (NNLO) in QCD, and we combine them with the all-order radiative corrections from a parton-shower simulation ($\mathrm{NNLO}+\mathrm{PS}$). Our method represents the first approach to $\mathrm{NNLO}+\mathrm{PS}$ event generation applicable to processes featuring a color singlet and a heavy-quark pair in the final state. The novel two-loop corrections are computed for massless bottom quarks, and the leading mass corrections are restored through a small-mass expansion. The calculation is carried out in the four-flavor scheme, and we find that the sizable NNLO QCD corrections lift the long-standing tension between lower-order predictions in four- and five-flavor schemes. Our predictions are compared to a CMS measurement for $Z$ boson plus $b$-jet production, achieving an excellent description of the data.

We investigate the electroweak phase transition (EWPT) within the inverted type-I two-Higgs-doublet model, where the observed 125 GeV Higgs boson is identified as the heavier $CP$-even scalar $H$. Through a comprehensive parameter-space scan consistent with current theoretical and experimental constraints, we identify regions supporting strong first-order EWPTs (SFOEWPTs), including multistep transitions. We find that two-step SFOEWPTs occur as frequently as one-step transitions, while three-step transitions can occur, albeit rarely. Crucially, the parameter spaces inducing one-step and two-step transitions are partially yet significantly separated: one-step transitions restrict the charged Higgs mass and $\tan \beta$ to $m_{H^{\pm }}\in [295,441]\mathrm{GeV}$ and $\tan \beta \in [4.2,8.8]$, whereas two-step transitions allow $m_{H^{\pm }}\in [100,350]\mathrm{GeV}$ and $\tan \beta \in [2.5,45.4]$. Notably, negative values of $\sin (\beta -\alpha )$ arise almost exclusively in one-step scenarios. We present the calculation of gravitational wave (GW) signal-to-noise ratios (SNRs) at Laser Interferometer Space Antenna for multistep EWPTs, finding that detectable GW signals ($\mathrm{SNR}>10$) predominantly emerge from two-step transitions. Furthermore, we demonstrate that the previously established correlation between the vacuum uplifting measure $\mathrm{\Delta }{\mathcal{F}}_0$ and EWPT strength ${\xi }_c$ persists only in one-step transitions and breaks down in multistep cases. Finally, we perform a dedicated collider analysis for representative SFOEWPT parameter points at the 1.5 TeV Compact Linear Collider, identifying $e^{+}{e}^{-}\to H^{+}{H}^{-}\to W^{+}{W}^{-}hh$ as a promising discovery channel. Enhanced $h\to \gamma \gamma$ branching ratios for negative $\sin (\beta -\alpha )$ motivate two complementary golden final states, $W^{+}{W}^{-}b\overline{b}{\tau }^{+}{\tau }^{-}$ and $W^{+}{W}^{-}b\overline{b}\gamma \gamma$, which demonstrate high discovery potential due to negligible Standard Model backgrounds.

The left-right model with the simplest Higgs structure has a $SU(2{)}_L$ doublet $H_L$, a $SU(2{)}_R$ doublet $H_R$, and a singlet $\sigma$ that couples to the doublets as $\sigma (|H_L{|}^2-|H_R{|}^2)$. The left-right symmetry has $H_L\leftrightarrow H_R$ and $\sigma \leftrightarrow -\sigma$. We study gravitational wave production and baryogenesis in the electroweak phase transitions in the model. For two benchmark points, $\sigma$ first gets a vev, followed by $H_R$ and then $H_L$. An interesting feature is that the vev of $H_L$ is initially much higher than its zero temperature value, leading to a more strongly first-order transition and higher frequency gravitational waves. An unusual benchmark point has the $\sigma$ vev at zero when the electroweak symmetry breaks. This results in both $H_L$ and $H_R$ vevs being equal and in the multi-TeV range. At a lower temperature, the $\sigma$ vev turns on, breaking the left-right symmetry and $H_L$ drops to its standard model value. Since the electroweak symmetry is broken at the multi-TeV scale, the frequency of gravitational waves will be much higher than usual. Baryogenesis is also discussed.

A class of extensions to the Standard Model adds hypothetical long-lived particles (LLPs) that have mass- or kinetic-mixing with neutral mesons, such as pions or rho mesons. The mixing can contribute significantly to the production of LLPs at proton accelerator experiments, and no consistent description of these production modes exists in the literature. In this paper, we develop a framework for studying different LLPs—dark photons, vector mediators coupled to the baryon current, and axionlike particles with different coupling patterns. In particular, we implement the production mechanisms in pythia8, study how the overall flux and kinematic distributions depend on the LLP’s mass, and compare various subprocesses where the mixing contributes—proton bremsstrahlung, meson decay, and production in the fragmentation chain. We find that our new description of LLP production predicts an integrated flux that differs from current approaches by one to two orders of magnitude, and highlight the unavoidable theoretical uncertainties coming from poor knowledge of the properties of heavy mesons.

In recent years, the quantum computing method has been used to address the sign problem in traditional Monte Carlo lattice gauge theory (LGT) simulations. We propose that the Coulomb gauge (CG) should be used in quantum simulations of LGT. Since the redundant degrees of freedom of gauge fields can be eliminated in CG, the Hamiltonian in CG does not need to be gauge invariant, allowing the gauge field to be discretized naively. Then the discretized gauge fields and fermion fields should be placed on momentum and position lattices, respectively. Under this scheme, the CG condition and Gauss’s law can be conveniently preserved by solving for the polarization vectors from algebraic equations. Furthermore, we discuss the mapping of gauge fields to qubits and evaluate the associated qubit and gate cost of this framework. We point out that this formalism is efficient for simulating hadron scattering processes on future fault-tolerant quantum computers. Finally, we calculate the vacuum expectation value of the U(1) plaquette operator and the Wilson loop on a classical device to test the performance of our discretization scheme.

Lattice gauge theories in varying dimensions, lattice volumes, and truncations offer a rich family of targets for Hamiltonian simulation on quantum devices. In return, formulating quantum simulations can provide new ways of thinking about the quantum structure of gauge theories. In this work, we consider pure $SU(3)$ gauge theory in two and three spatial dimensions in a streamlined version of the electric basis. We use a formulation of the theory that balances locality of the Hamiltonian and size of the gauge-invariant state space, and we classically pre-compute dictionaries of plaquette operator matrix elements for use in circuit construction. We build circuits for simulating time evolution on arbitrary lattice volumes, spanning circuits suitable for Noisy Intermediate-Scale Quantum era hardware to future fault-tolerant devices. Relative to spin models, time evolution in lattice gauge theories involves more complex local unitaries, and the Hilbert space of all quantum registers may have large unphysical subspaces. Based on these features, we develop general, volume-scalable tools for optimizing circuit depth, including pruning and fusion algorithms for collections of large multicontrolled unitaries. We describe scalings of quantum resources needed to simulate larger circuits and some directions for future algorithmic development.

The shape function of the $B$-meson defined in heavy quark effective theory plays a crucial role in the analysis of inclusive $B$ decays, and constitutes one of the dominant uncertainties in the determination of Cabbibo-Kobayashi-Maskawa matrix element $|V_{ub}|$. On the other hand, the conventional heavy meson shape function defined in QCD is also phenomenologically important and includes short-distance physics at energy scales of the heavy quark mass. In this work, we derive a factorization formula relating these two kinds of shape functions, which can be invoked to fully disentangle the effects from disparate scales $m_b$ and ${\mathrm{\Lambda }}_{\mathrm{QCD}}$, particularly to facilitate the resummation of logarithms $\ln m_b/{\mathrm{\Lambda }}_{\mathrm{QCD}}$. In addition, this factorization constitutes an essential component of the recently developed two-step factorization scheme, enabling lattice QCD calculations of light cone quantities of heavy meson. The results presented here pave the way for first-principles nonperturbative predictions of shape function in the near future.

We study the anomalous ${\pi }^0\to \gamma \gamma$ decay under an external uniform magnetic field in the framework of a two-flavor Nambu-Jona-Lasinio model. It is seen that the full decay width gets strongly reduced with the external field, and that the differential width is almost independent of the direction of the outgoing photons. We also find that the result for the total width can be very well approximated by a simple expression obtained at the lowest order in the chiral expansion, which is just a direct extension to finite magnetic fields of the well-known $B=0$ result that follows from the anomalous Wess-Zumino-Witten action. As a result, the magnetic suppression of the width can be understood in terms of the evolution of both the neutral pion mass and decay constant with the magnetic field.

In response to recent experimental findings from the BES III and LHCb Collaborations concerning the decay of open charm mesons into three pseudoscalars, we present evidence suggesting that the lightest scalar mesons can be characterized as diquark-antidiquark states mixed with the next-to-light, $q\overline{q}$, scalar mesons through six-fermion, instanton-induced interactions.

We investigate doubly charmed hexaquark states within the diquark picture, by employing the constituent quark model and the quark-interchange model as our theoretical frameworks. Using the Gaussian expansion method, we systematically study these states, with calculating various properties such as mass spectra, internal contributions of each Hamiltonian component, root-mean-square radii, and two-body strong decay widths. Our analysis of the mass spectra reveals no stable state in this system. Furthermore, the root-mean-square radii suggest that the doubly charmed hexaquark states exhibit a compact configuration. By examining the decay widths, we identify potentially detectable states and their primary decay channels within each subsystem. Despite the large decay phase space, we still find narrow states with total widths of less than 10 MeV. This study provides a theoretical foundation for understanding the structures and interactions of doubly charmed hexaquark states and offers valuable insights for future experimental searches.

We provide a new method to calculate the full microlocal description of the singularities of Feynman integrals. This is done by associating a unique constructible function to the system of partial differential equations (PDEs) annihilating the integral and from this function the singularities can directly be read-off. This function can be constructed explicitly even if the system of PDEs is unknown and describes both the location of the singularities and the number of (generalized) master integrals on them. Our framework is flexible enough to perform the calculation in any of the Lee-Pomeransky, Feynman, or momentum representations.

A new approach for embedding the renormalization group running of Newton’s constant and the cosmological constant in gravity is proposed. This approach is based on a gravitational Lagrangian that gives rise to a new class of modified gravity theories where $G$ and $\mathrm{\Lambda }$ are spacetime-dependent functions. The Lagrangian formulation can be interpreted as an effective gravitational action that encapsulates the scale dependence of $G$ and $\mathrm{\Lambda }$, arising from quantum effects in the early Universe. We show that the new formalism can be discussed partially using the framework and results of Horndeski modified gravity, excluding the equations of motion of the scalar field. The study explores aspects of this new gravity action. We also analyze an interesting nonsingular cosmological solution featuring power-law inflation, and we discuss the generation of scalar and tensor perturbations within this framework.

We construct a model for the nucleation of a wormhole within a Lorentzian spacetime by employing techniques from topological surgery and Morse theory. In our framework, a 0-surgery process describes the neighborhood of the nucleation point inside a compact region of spacetime, yielding a singular Lorentzian cobordism that connects two spacelike regions with different topologies. To avoid the singularity at the critical point of the Morse function, we employ the Misner trick of taking a connected sum with a closed 4-manifold—namely, ${\mathbb{CP}}^2$—to obtain an everywhere nondegenerate Lorentzian metric. This connected sum replaces the naked singularity with a region containing closed timelike curves. The obtained spacetime is nonsingular but violates all the standard energy conditions. Our construction, thus, shows that a wormhole can be “created” without singularities in classical general relativity.

To mitigate the severe information loss arising from widely adopted linear scale cuts in constraints on modified gravity parametrizations with weak lensing (WL) and large-scale structure (LSS) data, we introduce a novel alternative method for data reduction. This principal component analysis (PCA)-based framework extracts key features in the matter power spectrum arising from nonlinear effects in a set of representative gravity theories. By performing the analysis in the space of principal components, we can replace sweeping linear-only scale cuts with targeted cuts on the transformed data vector, ultimately reducing parameter bias and significantly tightening constraints. We forecast constraints on a minimal parametrized extension to $\mathrm{\Lambda }\mathrm{CDM}$ which includes modifications to the growth of structure and lensing of light ($\mathrm{\Lambda }\mathrm{CDM}+{\mu }_0+{\mathrm{\Sigma }}_0$) using mock stage-IV data for two simulated cosmologies: the $\mathrm{\Lambda }\mathrm{CDM}$ model and extended shift symmetric (ESS) gravity. Under the assumption of a Universe defined by $\mathrm{\Lambda }\mathrm{CDM}$ and general relativity, our method offers constraints on ${\mu }_0$ a factor of 1.65 tighter than traditional linear-only scale cuts. Crucially, our approach also provides the necessary constraining power to break key degeneracies in modified gravity without relying on $f{\sigma }_8$ measurements, introducing a promising new tool for the analysis of present and future WL and LSS photometric surveys.

High-energy astrophysical systems and compact objects are frequently modeled using ideal relativistic magnetohydrodynamic (MHD) or force-free electrodynamic (FFE) simulations, with the underlying assumption that the discretization from the numerical scheme introduces an effective (numerical) magnetic resistivity that adequately resembles an explicit resistivity. However, it is crucial to note that numerical resistivity can fail to replicate essential features of explicit resistivity. In this study, we compare the 1D resistive decay and 2D reconnection properties of four commonly used physical models. We demonstrate that the 1D Ohmic decay of current sheets via numerical dissipation in both ideal MHD and magnetodynamics (MD) is subdiffusive (i.e., sublinear in time), whereas explicit resistive FFE and resistive MHD simulations match the predictions of resistive theory adequately. For low-resolution, reconnecting current sheets in two dimensions, we show that ideal MHD and MD have an analog to the Sweet-Parker regime where the scaling of the reconnection rate depends directly on the resolution. At high resolutions, ideal MHD and MD have an asymptotic reconnection rate similar to resistive MHD. Furthermore, we find that guide field-balanced current sheets in ideal MHD and MD have a qualitative structure similar to that of one in resistive MHD. Similarly, a pressure-balanced current sheet in ideal MHD is found to have a qualitative structure similar to that of one in resistive MHD. For a guide field-balanced sheet, resistive FFE is found to have a nearly identical Sweet-Parker regime compared to resistive MHD and a similar asymptotic reconnection rate for large enough Lundquist numbers, but differs in the timescale for reconnection onset in the asymptotic regime. We discuss the implications of our findings for global simulations.

We investigate whether the ultrahigh energy neutrino inferred by the recent KM3NeT observation could have originated from an evaporating black hole. Given the characteristics of the black hole evaporation mechanism, any object capable of producing particles in the energy range of the detected event ($\sim 100–800\mathrm{PeV}$) must have a mass $M_{\mathrm{BH}}\lesssim {10}^7\mathrm{g}$. No known astrophysical mechanism can generate black holes of such low mass, leaving primordial black holes (PBHs)—potentially formed at the end of cosmic inflation—as the only viable candidates. Black holes with masses $M_{\mathrm{BH}}\lesssim {10}^7\mathrm{g}$ have lifetimes shorter than ${10}^{-5}$ seconds, meaning PBHs in this mass range should have fully evaporated by now. However, recent studies suggest that quantum effects, collectively referred to as the “memory burden,” may slow down black hole evaporation, potentially extending the lifetimes of low-mass PBHs to timescales comparable to or exceeding the Hubble time. We systematically explore the parameter space of memory-burdened PBHs, assuming that they constitute a fraction of the dark matter ($f_{\mathrm{PBH}}$) within current constraints, and identify viable regions that could explain the KM3–230213A event. We further predict the occurrence rate of similar events, and find that KM3NeT and future neutrino experiments could test this scenario over the next years.

Strong gravitational lenses come in many forms, but are typically divided into two populations: galaxies, and groups and clusters of galaxies. The largest objects in the Universe (i.e., galaxy clusters) are highly irregular and composed of many components due to a history of (or active) hierarchical mergers. In this work, we analyze the discrepancies in the observables of strongly lensed gravitational wave transients in both scenarios, namely relative magnifications, time delays, and image multiplicities. We compare the detection rates between the single spherical dark matter halo models found in the literature, and publicly available state-of-the-art cluster lens models. We find there to be approximately an order of magnitude fewer detection of strongly lensed transients in the realistic model case, likely caused by their loss of overall strong lensing optical depth. We also report detection rates in the weak lensing or single-image regime. Additionally, we find a systemic shift toward lower time delays between the brightest image pairs in the cases of the realistic models, as well as higher fractions of positive versus negative parity images, which was previously reported in the literature. This deviation in the joint relative magnification factor-time delay distribution will hinder the feasibility of the reconstruction of cluster-scale lenses through gravitational wave transients alone, but can still provide a lower limit on the lens mass.

The parametrized equation of state (EOS) of neutron stars is investigated by the Bayesian inference method with various constraints from both nuclear physics and modern astronomical observations, where the energy per particle is expanded as a polynomial function of the density. The expansion coefficients correspond to the properties of symmetric nuclear matter and the density dependence of the symmetry energy. The empirical values of the symmetry energy at subsaturation density and the density of crust-core phase transition are considered to limit the low-density behavior of EOS, i.e., $L_{\mathrm{sym}}$, while the speed of sound of neutron star matter and mass-radius observations of millisecond pulsars PSR $\mathrm{J}0030+0451$ and PSR $\mathrm{J}0740+6620$ are adopted to eliminate the high-order expansion coefficients, such as $Q_{\mathrm{sat}}$ and $Q_{\mathrm{sym}}$. Finally, our analysis reveals that the skewness coefficient $Q_{\mathrm{sat}}$ of the energy per nucleon in symmetric nuclear matter exhibits the strongest correlation with the speed of sound, constrained to $Q_{\mathrm{sat}}=-69.50_{-31.93}^{+16.52}\mathrm{MeV}$, whose uncertainties are much smaller than those of the experiments of heavy-ion collisions. The symmetry energy parameters are determined as follows: slope $L_{\mathrm{sym}}=34.32_{-11.85}^{+13.66}\mathrm{MeV}$, curvature $K_{\mathrm{sym}}=-58.45_{-89.46}^{+88.47}\mathrm{MeV}$, and skewness $Q_{\mathrm{sym}}=302.28_{-231.89}^{+251.62}\mathrm{MeV}$. Additionally, the radii of canonical ($1.4M_{\odot }$) and massive ($2.0M_{\odot }$) neutron stars are predicted as $R_{1.4}=11.85_{-0.15}^{+0.06}\mathrm{km}$ and $R_{2.0}=11.42_{-0.35}^{+0.23}\mathrm{km}$, respectively, with a maximum mass of $M_{\max }=2.12_{-0.05}^{+0.11}{M}_{\odot }$. The tidal deformability is ${\mathrm{\Lambda }}_{1.4}=303.57_{-45.22}^{+47.95}$ at $1.4M_{\odot }$, which is consistent with the analysis of the GW170817 event. The trace anomaly $\mathrm{\Delta }$ in the high density region increases when the causality of the speed of sound is taken.

Lepton pairs with opposite charges can form bound states known as “leptonium” through quantum electrodynamic interactions. Heavy quarkonia such as $J/\psi$ are abundantly produced at facilities like BESIII and the future Super Tau-Charm Facility (STCF). In this work, we investigate leptonium production in heavy quarkonium decays, specifically focusing on the processes $\mathcal{Q}⟶(l_1^{+}{l}_2^{-})[n]+\gamma$ ($l_{1,2}=\tau$, $\mu$, $e$) and $\mathcal{Q}⟶(l_1^{+}{l}_2^{-})[n]+l_1^{-}{l}_2^{+}$. Here, $\mathcal{Q}$ denotes the heavy quarkonium $J/\psi$ or $\mathrm{\Upsilon }$, while $n={{}^{1}S}_0$ or ${}^3{S}_1$ corresponds to para-leptonium and ortho-leptonium, respectively. With an annual production of $3.4\times {10}^{12}J/\psi$ events at STCF, there is significant potential to observe positronium $(e^{+}{e}^{-})$, muonium $({\mu }^{+}{e}^{-})$, and dimuonium $({\mu }^{+}{\mu }^{-})$. In particular, the ortho-dimuonium $({\mu }^{+}{\mu }^{-}){[}^3{S}_1]$ may be discovered at the future STCF, with an inclusive branching fraction of $\mathrm{Br}(J/\psi ⟶({\mu }^{+}{\mu }^{-}){[}^3{S}_1]+X)=1.5\times {10}^{-12}$.