Gravitational wave (GW) detectors routinely encounter transient noise bursts, known as glitches, which are caused by either instrumental or environmental factors. Because of their high occurrence rate, glitches can overlap with GW signals, as in the notable case of GW170817, the first detection of a binary neutron star merger. Accurate reconstruction and subtraction of these glitches is a challenging problem that must be addressed to ensure that scientific conclusions drawn from the data are reliable. This problem will exacerbate with third-generation detectors like Einstein Telescope (ET) due to their higher detection rates of GWs and the longer duration of signals within the sensitivity band of the detectors. Robust glitch mitigation algorithms are, therefore, crucial for maximizing the scientific output of next-generation GW detectors. For the first time, we demonstrate how the null stream inherent in ET’s unique triangular configuration can be leveraged by state-of-the-art glitch mitigation methodology to essentially undo the effect of glitches for the purpose of estimating the parameters of the source. The null-stream-based approach enables mitigation and subtraction of glitches that occur arbitrarily close to the peak of the signal without any significant effect on the quality of parameter measurements and achieves an order of magnitude computational speedup compared to when the null stream is not available. By contrast, without the null stream, significant biases can occur in the glitch reconstruction, which deteriorate the quality of subsequent measurements of the source parameters. This demonstrates a clear edge which the null stream can offer for precision GW science in the ET era.

The use of compactified hyperboloidal coordinates for metric formulations of the Einstein field equations introduces formally singular terms in the equations of motion whose numerical treatment requires care. In this paper we study a particular choice of constraint addition, choice of gauge and reduction fields in order to minimize the number of these terms in a spherically symmetric reduction of the dual-foliation generalized harmonic gauge formulation of general relativity. We proceed to the numerical implementation of a more aggressive compactification, as compared to our previous work. With the present setup there is a direct analogy with conformal compactification used in other approaches to the use of hyperboloidal coordinates. We present numerical results of constraints violating and satisfying perturbations on top of a Schwarzschild black hole. For small perturbations we recover the expected physics from linear theory, corresponding to quasinormal mode ringing and tail decay for a scalar field, both extracted directly at future null infinity from our numerical data.

We apply the framework of Vlasov perturbation theory ($\mathsf{VPT}$) to the two-loop matter power spectrum within $\mathrm{\Lambda }$ cold dark matter cosmologies. The main difference to standard perturbation theory (SPT) arises from taking the velocity dispersion tensor into account, and the resulting screening of the backreaction of UV modes renders loop integrals cutoff independent. $\mathsf{VPT}$ is informed about nonperturbative small-scale dynamics via the average value of the dispersion generated by shell-crossing, which impacts the evolution of perturbations on weakly nonlinear scales. When using an average dispersion from halo models, the $\mathsf{VPT}$ power spectrum agrees with the one from the simulation, up to differences from missing three-loop contributions. Alternatively, treating the average dispersion as a free parameter we find a remarkably stable prediction of the matter power spectrum from collisionless dynamics at percent level for a wide range of the dispersion scale. We quantify the impact of truncating the Vlasov hierarchy for the cumulants of the phase-space distribution function, finding that the two-loop matter power spectrum is robust to neglecting third and higher cumulants. Finally, we introduce and validate a simplified fast scheme fast $\mathsf{VPT}$ that can be easily incorporated into existing codes and is as numerically efficient as SPT.

Cosmic birefringence—the rotation of the polarization plane of light as it traverses the Universe—offers a direct observational window into parity-violating physics beyond the Standard Model. In this work, we revisit the anisotropic component of cosmic birefringence, which leads to the generation of $B$-mode polarization in the cosmic microwave background (CMB). Using an exact theoretical treatment beyond the thin last-scattering surface approximation, we constrain the amplitude of anisotropic birefringence with combined polarization data from SPTpol, ACT, POLARBEAR, and BICEP. The joint analysis yields a best-fit amplitude of $A_{\mathrm{CB}}=0.42_{-0.34}^{+0.40}\times {10}^{-4}$, consistent with zero within $2\sigma$, and we place a 95% confidence-level upper bound of $A_{\mathrm{CB}}<1\times {10}^{-4}$. The constraint is not dominated by any single experiment and remains robust under the inclusion of a possible isotropic rotation angle. These results provide leading constraints on anisotropic cosmic birefringence from CMB $B$-mode polarization and illustrate the potential of upcoming experiments to improve sensitivity to parity-violating effects in the early Universe.

Motivated by new baryon acoustic oscillation (BAO) data and the significant results recently published by the DESI DR2 Collaboration, this study presents a Markov chain Monte Carlo analysis of all currently viable $f(R)$ models using this new dataset and compares its constraining power with that of previous BAO compilations. A corresponding Bayesian model comparison is then carried out. The results reveal, for the first time, very strong statistical evidence in favor of $f(R)$ models over the standard $\mathrm{\Lambda }\mathrm{CDM}$ scenario. The analysis also incorporates data from cosmic chronometers and the latest $\mathrm{Pantheon}++\mathrm{SH}0\mathrm{ES}$ supernovae compilation.

Recent cosmological measurements suggest the possibility of an anisotropic universe. As a result, the Bianchi Type I metric, being the simplest anisotropic extension to the standard Friedmann-Lemaître-Robertson-Walker metric has been extensively studied. In this work, we show how the recombination history should be modified in an anisotropic universe and derive observables by considering the null geodesic. We then constrain the locally rotationally symmetric Bianchi type I model by performing Markov chain Monte Carlo with the acoustic scales in cosmic microwave background and baryon acoustic oscillation data, together with local measurements of $H(z)$ and pantheon supernova data. Our results reveal that the anisotropic model is not statistically preferred over the $\mathrm{\Lambda }$ cold dark matter model, and we obtain a tight constraint on the anisotropy that generally agrees with previous studies under a maximum temperature anisotropy fraction of $2\times {10}^{-5}$. Besides, we also present constraints based on a relaxed maximum temperature anisotropy. We stress that there is a significant difference between the geodesic-based observables and the naive isotropic analogies when there is a noticeable anisotropy. However, the changes in recombination history are insignificant even under the relaxed anisotropy limit.

The collision of two neutron stars is a rich source of information about nuclear physics. In particular, the kilonova signal following a merger can help us elucidate the role of neutron stars in nucleosynthesis, and informs us about the properties of matter above nuclear saturation. Approximate modeling of neutrinos remains an important limitation to our ability to make predictions for these observables. Part of the problem is the fermionic nature of neutrinos. By the exclusion principle, the expected value $f_{\nu }$ for the number of neutrinos in a quantum state is at most 1. Any process producing neutrinos is suppressed by a blocking factor $(1-f_{\nu })$. Recent simulations focused on neutrino physics mostly use a gray two-moment scheme to evolve neutrinos. This evolves integrals of $f_{\nu }$ over momentum space, preventing direct calculations of blocking factors. Monte Carlo methods may be an attractive alternative, providing access to the full distribution of neutrinos. Their current implementation is, however, inadequate to estimate $f_{\nu }$: in our most recent simulations, a single Monte Carlo packet causes, in the worst cases, estimates of $f_{\nu }$ to jump from $f_{\nu }=0$ to $f_{\nu }\sim {10}^5$. While this is concerning, this brazen violation of the fermionic nature of neutrinos has been largely inconsequential, as the interactions used in simulations avoid direct calculations of $f_{\nu }$. We are, however, reaching a level of modeling at which this problem can no longer be ignored. Here, we discuss the relatively simple origin of this issue. We then show that very rough estimates of $f_{\nu }$ can in theory be obtained in merger simulations, but that they will require a combination of unintuitive weighting schemes for Monte Carlo packets and smoothing of the neutrino distribution at coarser resolution than what the merger simulation uses.

Cosmic-ray electrons and positrons (CREs) offer valuable insights into the origins of local cosmic rays, as they rapidly cool in interstellar magnetic and radiation fields, limiting their propagation range. The CRE spectrum reveals a spectral break around 1 TeV, followed by a continuous power-law behavior that possibly extends beyond 40 TeV. Deviations from a pure power-law in this spectrum could provide important clues about the local origins of CREs. However, due to the rapidly falling flux of CRE, the ratio of hadron/CRE increases with energy, making the rejection more and more challenging. Equipped with a large detection aperture and strong background rejection capability, LHAASO has the potential to extend CRE spectrum measurements beyond 25 TeV, which is almost the highest energy measured by existing experiments. In this work, we study the detector performance and explore the optimized background rejection of cosmic nuclei background specifically for CRE observations in LHAASO. Our analysis reveals that muon-poor nuclei showers have a strong dependence on the hadronic model when estimating the cosmic nuclei background and rejection capability. Consequently, we derived a 90% CL upper limit for the CRE spectrum from 25 to 160 TeV, providing a new and restrictive constraint in the hundreds of TeV range for the first time.

We investigate electron-positron pair production from the quantum vacuum in spatially asymmetric, oscillating electric fields using the Dirac-Heisenberg-Wigner formalism in $1+1$ dimensions. The electric field is strongly space-time dependent [$E(x,t){\mathbf{e}}_x$] and characterized by both spatial asymmetry and temporal oscillations. The temporal dynamics incorporate multiple modulation mechanisms, including variations in central frequency, frequency chirping, and phase modulation. Our results show that spatial asymmetry significantly enhances pair production compared to symmetric field configurations. Furthermore, optimal tuning of temporal parameters, such as the frequency $\omega$ and chirp parameter $b$, can further amplify the yield. For $\omega \gtrsim 0.4m$, the momentum spectra exhibit oscillatory structures dominated by multiphoton processes, whereas low-frequency fields ($\omega \lesssim 0.3m$) result in tunneling-dominated Gaussian distributions. Chirped fields introduce spectral asymmetry and interference patterns, with peak yields increasing by up to a factor of 9 for $\omega =0.7m$ and $b=0.5\omega /\tau$. These findings offer a promising approach for optimizing vacuum pair production in experimentally realizable spatiotemporal field configurations.

Investigations show that a time-varying $\delta -{\delta }^{\prime }$ mirror gives rise to asymmetrical vacuum radiation on its two sides, enabling one to gain propelling force from the quantum vacuum excitation. In this work, we propose a design of a Casimir device to gain propelling force by exciting a vacuum asymmetrically with conventional $\delta$ mirrors. This device is experimentally feasible. It consists of a cavity made up of two mirrors, a perfectly reflective one on the left and another one with time dependent transparency on the right. All particles generated from the vacuum are ultimately right moving, so the cavity obtains a left-pointing propelling force.

We present the renormalization functions of dimensionally regularized ${\varphi }^3$ theory in six dimensions up to loop order six in the minimal subtraction scheme.

Employing a kinetic framework, we calculate all transport coefficients for relativistic dissipative (second-order) hydrodynamics for arbitrary particle masses in the 14-moment approximation. Taking the nonrelativistic limit, it is shown that the relativistic theory reduces to the Grad equations computed in the “order-of-magnitude” approach.

In a canonical type-I seesaw scenario, the Standard Model is extended with three singlet right-handed neutrinos (RHNs) $N_i,i=1$, 2, 3 with masses $M_i,i=1$, 2, 3 to simultaneously explain sub-eV masses of light neutrinos and baryon asymmetry of the Universe at high scales. In this paper, we show that a relatively low-scale thermal leptogenesis accompanied by gravitational wave signatures is possible when the type-I seesaw is extended with a singlet fermion ($S$) and a singlet scalar ($\rho$), where $S$ and $\rho$ are odd under a discrete $Z_2$ symmetry. We also add a vectorlike fermion doublet $\mathrm{\Psi }$ and impose a $Z_2^{\prime }$ symmetry under which both $N_1$ and $\mathrm{\Psi }$ are odd while all other particles are even. This gives rise to a singlet-doublet Majorana fermion dark matter in our setup. At a high scale, the $Z_2$ symmetry is broken spontaneously by the vacuum expectation value of $\rho$ and leads to (i) mixing between RHNs ($N_2$, $N_3$) and $S$ and (ii) formation of Domain walls (DWs). In the former case, the final lepton asymmetry is generated by the out-of-equilibrium decay of $S$, which dominantly mixes with $N_2$. We show that the scale of thermal leptogenesis can be lowered to $M_S\sim 2\times {10}^6\mathrm{GeV}$, which is 3 orders of magnitude lower than the thermal leptogenesis in canonical type-I seesaw. In the latter case, the disappearance of the DWs gives observable gravitational wave signatures, which can be probed at LISA, DECIGO, $\mu \mathrm{ARES}$ etc.

We examine the structure of off-shell effective actions arising from chiral and gravitational anomalies, focusing on the $⟨JJ{J}_A⟩$ (vector/vector/axial-vector) and $⟨TT{J}_A⟩$ (stress-energy tensors/axial-vector) correlators, relevant in the analysis of anomaly-driven interactions in perturbation theory. Our approach employs both perturbative methods and techniques in conformal field theory within momentum space, extended to encompass chiral anomalies. The analysis centers on the presence of both particle poles and anomaly poles within these interactions, characterizing their behavior both in the conformal and nonconformal limits. Through explicit computations, we show that universal sum rules in the longitudinal sector regulate these interactions for all kinematic conditions, extending previous analysis. We discuss the resulting spectral flow, an “area law” of the absorptive part of the anomaly form factors as one moves away from or returns to the conformal point. These features are absent in the local effective action of anomaly interactions, commonly used in the description of axionlike particles. Our results further show that anomaly poles correspond to true particle poles only in the conformal limit, when the interaction describes a massless S-matrix process supported on a null surface. Under these conditions, they can be effectively described by two kinetically mixed pseudoscalar fields propagating on the light cone. These studies find application in polarized deeply inelastic scattering, axionlike dark matter, and analog systems such as topological materials.

High luminosity colliders and fixed target facilities using proton beams are sensitive to new weakly coupled degrees of freedom across a broad mass range. Among the various production modes, bremsstrahlung is particularly important for dark sector degrees of freedom with masses between 0.5 and 2.0 GeV, due to mixing with hadronic resonances. In this paper, we revisit the calculation of dark vector production via initial state radiation in non-single-diffractive scattering, using an improved treatment of the splitting functions and timelike electromagnetic form factors. The approach is benchmarked by applying an analogous calculation to model inclusive $\rho$-meson production, indicating consistency with data from NA27 in the relevant kinematic range.

The kinetic mixing (KM) portal mandates the existence of at least one new gauge boson, the dark photon (DP) based on the group $U(1{)}_D$, which mixes with the Standard Model (SM) photon via loops of other new heavy particles carrying both SM and dark charges called portal matter (PM). Arguments exist based on the renormalization group equations running of the $U(1{)}_D$ gauge coupling suggesting that at higher scales $U(1{)}_D$ becomes part of a more complex non-Abelian group, a simple example being just the SM-like $G_D=SU(2{)}_I\times U(1{)}_{Y_I}$. In our past analyses, it was always assumed that $G_D$ broke in a SM-like manner directly to the DP’s $U(1{)}_D$ which then subsequently broke at low energies $\lesssim 1\mathrm{GeV}$. However, this need not be the case, and $G_D$ can instead break to $U(1{)}_{T_{3I}}\times U(1{)}_{Y_I}$, with $T_{3I}$ being the diagonal generator of $SU(2{)}_I$, now producing two light gauge bosons which obtain masses at the $\lesssim 1\mathrm{GeV}$ scale. In this paper, we explore the phenomenology of a very simple realization of this kind of alternative setup employing non-Abelian KM and having a minimal, leptonlike PM sector, demonstrating its distinctive nature in comparison to the previously examined symmetry breaking path. The effects of interference between these gauge bosons on thermal dark matter annihilation, the production of new heavy gauge, and Higgs and PM states at colliders, as well as the corresponding signatures for the light dark gauge bosons are examined. Collider signatures of this setup are found to be particularly challenging.

We investigate the connection between the entanglement entropy in scattering processes and the dynamics of electroweak phase transitions. Recent work has shown that the scattering entanglement entropy can provide new insight into Standard Model parameters. In this study, we propose that the maximum of the entanglement entropy in scattering amplitudes may serve as a diagnostic for first-order electroweak phase transitions in the early Universe. We analyze a simplified extension of the Standard Model consisting of the Higgs boson $h$ coupled to $O(N)$ real singlet scalars $S$ via the Higgs portal coupling ${\lambda }_{hS}$. By explicitly calculating the maximum entanglement entropy, we demonstrate that it grows with increasing ${\lambda }_{hS}$, and that both first-order and strong first-order electroweak phase transitions are favored in regions of parameter space with large maximum entropy. Our results suggest that entanglement-based observables may encode meaningful information about the underlying dynamics of electroweak symmetry breaking and provide a novel perspective on phase transition phenomena.

Composite asymmetric dark matter (ADM) is the framework that naturally explains the coincidence of the baryon density and the dark matter density of the Universe. Through a portal interaction sharing particle-antiparticle asymmetries in the Standard Model and dark sectors, dark matter particles, which are dark-sector counterparts of baryons, can decay into antineutrinos and dark-sector counterparts of mesons (dark mesons) or dark photon. Subsequent cascade decay of the dark mesons and the dark photon can also provide electromagnetic fluxes at late times of the Universe. The cosmic-ray constraints on the decaying dark matter with the mass of 1–10 GeV has not been well studied. We perform comprehensive studies on the decay of the composite ADM by combining the astrophysical constraints from $e^{\pm }$ and $\gamma$ ray. The constraints from cosmic-ray positron measurements by AMS-02 are the most stringent at $\gtrsim 2\mathrm{GeV}$: a lifetime should be larger than the order of ${10}^{26}\mathrm{s}$, corresponding to the cutoff scale of the portal interaction of about ${10}^8–{10}^9\mathrm{GeV}$. We also perform the dedicated analysis for the neutrino monoenergetic signals at Super-Kamiokande and Hyper-Kamiokande due to the atmospheric neutrino background in the energy range of our interest.

The magnetic polarizabilities of octet baryons are examined close to the physical quark-mass point using the background-field method in lattice QCD. For the first time, quantitative evidence of a light-quark exceptional configuration problem is presented. This exploratory calculation shows how these exceptional configurations have hindered previous attempts to determine magnetic polarizabilities near the physical mass point. The origin of the exceptional configuration problem lies in the use of a Wilson-type fermion action on electroquenched gauge-field configurations, where the dynamical-fermion gauge-field generation algorithm ignores the electric charges of the quarks. Changes in the fermion determinant that would suppress some gauge fields in the background magnetic field are neglected, leaving improbable gauge fields that generate large additive mass renormalizations which manifest as significant outliers in correlation-function distributions. The nature and extent of the exceptional configuration problem is illustrated through the development of an algorithm for the systematic identification and removal of the exceptional configurations. We find the light up and down quarks to be problematic, especially the up quark with its larger electric charge. The heavier mass of the strange quark protects the hyperon correlation functions to some extent. However, these also show some change upon the removal of exceptional configurations. Upon removing exceptional configurations, we find our results to be in accord with the behavior anticipated by chiral perturbation theory. However, we emphasize that there is no first-principles justification for the removal of exceptional configurations and, in light of the severity of the problem, we recommend the alternative formalism offered through the consideration of four-point function methods.

Baryon-antibaryon generalized distribution amplitudes (GDAs) give an access to timelike gravitational form factors (GFFs), which are complementary to the spacelike ones, which can be deduced from the hadronic generalized parton distributions (GPDs) measured in deep exclusive electroproduction processes. They allow to probe the GFFs of unstable baryons in the baryon octet, since the second moments of hadronic GDAs lead to the timelike GFFs. These GDAs can be measured in the process $e^{+}{e}^{-}\to B\overline{B}\gamma$, in the generalized Bjorken regime where the invariant mass of the $B\overline{B}$ pair is near threshold at high energy facilities, such as BESIII, Belle II, and the proposed Super Tau-Charm Facility. In this work, we investigate this process using the QCD collinear factorization framework, where the scattering amplitudes are expressed in terms of the baryon timelike electromagnetic (EM) FFs and Compton FFs. We also provide a numerical estimate of the cross sections with a model for baryon-antibaryon GDAs. Our work provides us a possibility to extract the timelike baryon GFFs from near future experimental measurements, and these GFFs may be further used to study longstanding questions in hadronic physics such as the baryon spin decomposition and D-term.