In this paper, we find new scalarized black holes by coupling a scalar field with the Gauss-Bonnet invariant in teleparallel gravity. The teleparallel formulation of this theory uses torsion instead of curvature to describe the gravitational interaction, and it turns out that, in this language, the usual Gauss-Bonnet term in four dimensions decays in two distinct boundary terms, the teleparallel Gauss-Bonnet invariants. Both can be coupled individually or in any combination to a scalar field, to obtain a teleparallel Gauss-Bonnet extension of the teleparallel equivalent of general relativity. The theory we study contains the familiar Riemannian Einstein-Gauss-Bonnet gravity theory as a particular limit and offers a natural extension, in which scalarization is triggered by torsion and with new interesting phenomenology. We demonstrate numerically the existence of asymptotically flat scalarized black hole solutions and show that, depending on the choice of coupling of the boundary terms, they can have a distinct behavior compared to the ones known from the usual Einstein-Gauss-Bonnet case. More specifically, nonmonotonicity of the metric functions and the scalar field can be present, a feature that was not observed until now for static scalarized black hole solutions.

The planning and design of future experiments rely heavily on forecasting to assess the potential scientific value provided by a hypothetical set of measurements. The Fisher information matrix, due to its convenient properties and low computational cost, provides an especially useful forecasting tool. However, the Fisher matrix only provides a reasonable approximation to the true likelihood when data are nearly Gaussian distributed and observables have nearly linear dependence on the parameters of interest. Also, Fisher forecasting techniques alone cannot be used to assess their own validity. Thorough sampling of the exact or mock likelihood can definitively determine whether a Fisher forecast is valid, though such sampling is often prohibitively expensive. We propose a simple test, based on the derivative approximation for likelihoods (DALI) technique, to determine whether the Fisher matrix provides a good approximation to the exact likelihood. We show that the Fisher matrix becomes a poor approximation to the true likelihood in regions where two-dimensional slices of level surfaces of the DALI approximation to the likelihood differ from two-dimensional slices of level surfaces of the Fisher approximation to the likelihood. We demonstrate that our method accurately predicts situations in which the Fisher approximation deviates from the true likelihood for various cosmological models and several data combinations, with only a modest increase in computational cost compared to standard Fisher forecasts.

The cosmic microwave background (CMB) is a powerful probe of early-universe physics but is only observed after passing through large-scale structure, which changes the observed spectra in important model-dependent ways. This is of particular concern given recent claims of significant discrepancies with low redshift datasets when a standard $\mathrm{\Lambda }\mathrm{CDM}$ model is assumed. By using empirical measurements of the CMB lensing reconstruction, combined with weak priors on the smoothness of the lensing spectrum, foregrounds, and shape of any additional integrated Sachs-Wolfe effect, we show how the early-universe parameters can be constrained from CMB observations almost independently of the late-time evolution. This provides a way to test new models for early-universe physics, and measure early-universe parameters, independently of late-time cosmology. Using the empirical measurement of lensing keeps the size of the effect of late-time modeling uncertainty under control, leading to only modest increases in error bars of most early-universe parameters compared to assuming a full evolution model. We provide robust constraints on early-$\mathrm{\Lambda }\mathrm{CDM}$ model parameters using the latest Planck PR4 data and show that with future data marginalizing over a single lensing amplitude parameter is sufficient to remove sensitivity to late-time cosmological model only if the spectral shape matches predictions.

Fallback supernovae and the collapsar scenario for long gamma-ray bursts and hypernovae have received considerable interest as pathways to black-hole formation and extreme transient events. Consistent simulations of these scenarios require a general relativistic treatment and need to deal appropriately with the formation of a singularity. Free evolution schemes for the Einstein equations can handle the formation of black holes by means of excision or puncture schemes. However, in constrained schemes, which offer distinct advantages in long-term numerical stability in stellar collapse simulations over well above ${10}^4$ light-crossing timescales, the dynamical treatment of black-hole spacetimes is more challenging. Building on previous work on excision in conformally flat spacetimes, we here present the implementation of a black-hole excision scheme for supernova simulations with the coconut-fmt neutrino transport code. We describe in detail a choice of boundary conditions that ensures long-time numerical stability, and also address upgrades to the hydrodynamics solver that are required to stably evolve the relativistic accretion flow onto the black hole. The scheme is currently limited to a spherically symmetric metric, but the hydrodynamics can be treated multidimensionally. For demonstration, we present a spherically symmetric simulation of black-hole formation in an $85M_{\odot }$ star, as well as a two-dimensional simulation of the fallback explosion of the same progenitor. These extend past 9 and 0.3 s after black-hole formation, respectively.

Starting from the relativistic Brueckner-Hartree-Fock theory for nuclear matter and the Dyson-Schwinger equation approach for quark matter, the possible hadron-quark phase transition in the interior of a neutron star is explored. The first-order phase transition and crossover are studied by performing the Maxwell construction and three-window construction respectively. The mass-radius relation and the tidal deformability of the hybrid star are calculated and compared to the joint mass-radius observation of a neutron star and the constraints from gravitational wave detection. For the Maxwell construction, no stable quark core is found in the interior of a neutron star. For the three-window construction, the parameters of the smooth interpolation function are chosen in such a way to keep the thermodynamic stability and lead to a moderate crossover density region. To support a two-solar-mass neutron star under the three-window construction, the effective width of medium screening effects in quark matter should be around 0.35 GeV.

Gravitational-wave backgrounds are expected to arise from the superposition of gravitational-wave signals from a large number of unresolved sources and also from the stochastic processes that occurred in the early Universe. So far, we have not detected any gravitational-wave background, but with the improvements in the detectors’ sensitivities, such detection is expected in the near future. The detection and inferences we draw from the search for a gravitational-wave background will depend on the source model, the type of search pipeline used, and the data generation in the gravitational-wave detectors. In this paper, we focus on the effect of the data generation process, specifically the calibration of the detectors’ digital output into strain data used by the search pipelines. Using the calibration model of the current LIGO detectors as an example, we show that for power-law source models and calibration uncertainties $\lesssim 10\%$, the detection of isotropic gravitational-wave background is not significantly affected. We also show that the source parameter estimation and upper limit calculations get biased. For calibration uncertainties of $\lesssim 5\%$, the biases are not significant ($\lesssim 2\%$), but for larger calibration uncertainties, they might become significant, especially when trying to differentiate between different models of isotropic gravitational-wave backgrounds.

One-loop integrands can be written in terms of a simple, process-independent basis. We show that a similar basis exists for integrands of phase-space integrals for the real-emission contribution at next-to-leading order. Our demonstration deploys techniques from computational algebraic geometry to partial-fraction integrands in a systematic way. This takes the first step toward a decomposition of phase-space integrals in terms of a basis of master integrals.

We present a new determination of the generalized parton distributions (GPDs) with their uncertainties at zero skewness, $\xi =0$, through a simultaneous analysis of all available experimental data of the nucleon electromagnetic form factors (FFs), nucleon charge and magnetic radii, proton axial FFs (AFFs), and wide-angle Compton scattering (WACS) cross sections for the first time, and we investigate whether there is any tension between these data. This can be considered the most comprehensive analysis of GPDs at $\xi =0$ performed so far. We show that such an analysis provides the simultaneous determination of three kinds of GPDs: namely $H^q$, ${\tilde{H}}^q$, and $E^q$, considering also the sea-quark contributions. As a result, we find that the inclusion of the WACS and AFF data at larger values of the momentum transfer squared $Q^2=-t$ can put new constraints on GPDs and change them drastically in some cases. We show that there is a considerable tension between the WACS and the proton magnetic form factor ($G_M^p$) data, especially at larger values of $-t$. However, we indicate that the results for the gravitational FF $M_2$ and the proton total angular momentum $J^p$ calculated using the extracted GPDs are in relatively good agreement with the light-cone QCD sum rules (LCSRs) and lattice QCD predictions when the sea-quark contributions are considered and both WACS and $G_M^p$ data are included in the analyses simultaneously.

In many-cycle plane waves at intermediate intensities, the nonlinear trident process can be well approximated by the two sequential steps of nonlinear Compton scattering of a polarized real photon followed by its transformation into an electron-positron pair via nonlinear Breit-Wheeler pair creation. We investigate this two-step process in the intermediate intensity regime by employing the locally monochromatic approximation for each step and numerically evaluating resulting expressions. When photon polarization is included, it is found to produce an order 10% decrease in the trident rate: the importance of polarization increases at lower intensities, and decreases at higher intensities. Its importance persists at higher intensities in a linearly polarized background, but disappears at high intensities in a circularly polarized background. If the two steps are made to take place in two linearly polarized plane wave pulses with perpendicular polarizations, the pair yield can be increased by approximately 30% compared to two plane waves with the same polarization. It is also shown that harmonic structures in the Compton step can be passed to the pair step if the Compton edge is at an energy of the order of the threshold for linear Breit-Wheeler.

In this paper we consider a minimal classically conformal U(1) model of fermionic dark matter. We calculate the one loop effective potential which generates the mass scale quantum mechanically via dimensional transmutation in the spirit of Gildener and Weinberg, and examine the effects of the new dark sector on the Standard Model Higgs as well as how the dark fermions receive a mass and can produce the observed relic abundance. We then consider constraints on the model coming from collider and direct detection experiments before calculating the thermal effects on the potential in the early Universe. We examine the nature and conditions for a strongly first-order phase transition in our model and calculate the associated gravitational wave signal and compare to the sensitivities of current and proposed experiments.

Supersymmetry (SUSY) is a highly motivated theoretical framework, whose scale of breaking may be at petaelectronvolt (PeV) energies, to be consistent with null searches at the Large Hadron Collider. SUSY breaking through a first-order phase transition may have occurred in the early universe, leading to potential gravitational wave signals. Constructing a realistic model for gauge-mediated supersymmetry breaking, we show that such a transition can also induce masses for heavy right-handed neutrinos and sneutrinos, whose $CP$-violating decays give leptogenesis at the PeV scale, and a novel mechanism of neutrino mass generation at one loop. For the same models we predict the possible gravitational wave signals, and we study the possibility of production of primordial black holes during the phase transition.

Searches for axionlike particles (ALPs) are motivated by the strong $CP$ problem in particle physics and by unexplained dark matter in astrophysics. In this paper, we discuss novel ALP searches using monoenergetic nuclear deexcitation photons from a beam dump, using the isotope decay-at-rest (IsoDAR) experiment as an example. We show that IsoDAR can set limits that close a gap in traditional QCD axion searches using the ALP-photon coupling, as well as provide sensitivity to large regions of new parameter space in models where ALPs couple to nucleons and electrons. We also show how isotope decay-at-rest experiments may be designed to improve potential ALP production and optimize detection sensitivity.

It has been known for some time that the cosmological bound on the invisible axion scale can be avoided by an early phase of strong QCD. While most approaches rely on theories where the strong coupling constant is determined through the expectation value of some scalar field, we show that this mechanism can also be implemented into the benchmark Kim-Shifman-Vainshtein-Zakharov and Dine-Fischler-Srednicki-Zhitnitsky models when the early phase of strong QCD emerges by the modification of the running coupling during inflation. For both models the physics that are responsible for making QCD strong do not displace the axions minimum by too much, so that the efficiency of the relaxation is controlled by parameters of the theory and the number of inflationary $e$-folds. In particular, we consider the case of very efficient relaxation where the axion abundance is dominated by inflationary quantum and postinflationary thermal fluctuations. Within this situation we identify the parameter space compatible with all cosmological constrains and derive conditions on the reheating temperature and the QCD scale during inflation that result in the axion making up all the dark matter. Because of duality below the Peccei-Quinn scale and a minor influence of the Kim-Shifman-Vainshtein-Zakharov and Dine-Fischler-Srednicki-Zhitnitsky fields on the running, our findings also apply to a minimal two-form implementation of the axion.

Because of the difficulty in detecting final state taus, the mixing parameter $|V_{\tau N}{|}^2$ for heavy neutrino $N$ is not well studied at current experiments, compared with other mixing parameters $|V_{eN}{|}^2$ and $|V_{\mu N}{|}^2$. In this paper, we focus on a challenging scenario where $N$ mixes with active neutrino of tau flavor only, i.e., $|V_{\tau N}{|}^2\ne 0$ and $|V_{eN}{|}^2=|V_{\mu N}{|}^2=0$. We derive current constraints on $|V_{\tau N}{|}^2$ from the rare $Z$-boson decay and electroweak precision data (EWPD). To forecast the future limits, we also investigate the signal $pp\to {\tau }^{\pm }{\tau }^{\pm }jj$ via a Majorana heavy neutrino at future proton-proton colliders. To suppress the background, both taus are required to decay leptonically into muons, leading to the final state containing two same sign muons, at least two jets plus moderate missing energy. The signal and relevant background processes are simulated at the HL-LHC and SppC/FCC-hh with center-of-mass energy of 14 TeV and 100 TeV. The preselection and multivariate analyses based on machine-learning are performed to reduce background. Limits on $|V_{\tau N}{|}^2$ are shown for heavy neutrino mass in the range 10–1000 GeV based on measurements from the rare $Z$-boson decay and EWPD, and searches at the HL-LHC and SppC/FCC-hh with integrated luminosities of 3 and $20{\mathrm{ab}}^{-1}$.

We address finite volume effects of lattice QCD calculations in background magnetic fields. Using chiral perturbation theory at next-to-leading order, volume effects are calculated for thermodynamic quantities: the chiral condensate, pressure anisotropy, and magnetization. The neutral pion effective action in a finite volume is additionally derived. For these charge neutral observables, volume and source averaging are shown to capitalize on magnetic periodicity, which is the remnant translational invariance of the finite-volume theory. For a fixed magnetic field strength, certain volume and source averaged quantities are independent of the size of the lattice transverse to the magnetic field. Despite this simplifying feature, finite volume corrections to the magnetic field dependence of the chiral condensate and neutral pion magnetic polarizability can be non-negligible. The pressure anisotropy at fixed magnetic flux, moreover, appears acutely sensitive to the lattice volume in the chiral regime.

We study the meson contribution to the equation of state of the 2-flavor Polyakov-loop Nambu–Jona-Lasinio model, including the full momentum dependence of the meson polarization loops. Within the Beth-Uhlenbeck approach, we demonstrate that the contribution from the quark-antiquark continuum excitations in the spacelike region ${\omega }^2-q^2<0$, i.e., the Landau damping, leads to an increase of the pressure for temperatures $\gtrsim 0.8T_c^{\chi }$ and a significant meson momentum cutoff dependence in the mesonic pressure and the QCD trace anomaly. We investigate the dependence of the results on the choice of the Polyakov-loop potential parameter $T_0$. From the dependence of the mesonic pressure on the current quark mass, by means of the Feynman-Hellmann theorem, we evaluate the contribution of the pion quasiparticle gas and Landau damping to the chiral condensate.

In the light of $SU(3)$ flavor symmetry, the effective interaction Hamiltonian in tensor form is obtained by virtue of group representation theory. The strong and electromagnetic breaking effects are treated as a spurion octet so that the flavor singlet principle can be utilized as the criterion to determine the form of effective Hamiltonian. Two body decays of both baryonic and mesonic final states are parametrized in the uniform scheme, based on which the relative phase between the strong and electromagnetic amplitudes is studied for various charmonium decay modes, including ${\psi }^{\prime }$ and/or $J/\psi$ decay to octet baryon pair, decuplet baryon pair, decuplet-octet baryon final state, and pseudoscalar-pseudoscalar meson final state. In data analysis of samples taken in $e^{+}{e}^{-}$ collider, the details of experimental effects, such as energy spread and initial state radiative correction, are taken into consideration in order to make full use of experimental information and acquire the accurate and delicate results.

We explore the possibility of using the dead cone of heavy quarks as a region of the Lund plane where medium-induced gluon radiation can be isolated and characterized. The filling of the dead cone by medium-induced gluons is expected to be the result of the interplay between the minimum angle of such radiation due to transverse momentum broadening and the dead-cone angle. Since the measurement of a fully corrected Lund plane in heavy-ion collisions is currently challenging, we propose to use jet grooming techniques to identify a particular splitting in the jet tree that is both perturbative and sensitive to the dead-cone effect. To that end, we propose a new jet substructure groomer, dubbed Late-$k_t$, that selects the most collinear splitting in a QCD jet above a certain transverse momentum cutoff $k_{t,\mathrm{cut}}$. The role of $k_{t,\mathrm{cut}}$ is to guarantee perturbative splittings, while selecting the most collinear splitting enhances the sensitivity to mass effects. As a proof of concept, we study the angular distribution of the splitting tagged by Late-$k_t$ both analytically and with Monte Carlo simulations. First, we derive the logarithmic resummation structure in vacuum and demonstrate its capability to distinguish between inclusive and heavy-flavored jets. Next, we extend the calculation for in-medium jets and show that medium-induced emissions lead to an enhancement of collinear emissions below the dead-cone angle. Numerically, we demonstrate an excellent resilience of Late-$k_t$ against uncorrelated thermal background, thus confirming this observable as a potential candidate to unveil medium dynamics around the dead-cone regime.

We demonstrate that fermion masses in the Standard Model (SM) can be constrained by the dispersion relations obeyed by hadronic and semileptonic decay widths of a fictitious heavy quark $Q$ with an arbitrary mass. These relations, imposing stringent connections between high-mass and low-mass behaviors of decay widths, correlate a heavy quark mass and the chiral symmetry breaking scale. Given the known input from leading-order heavy quark expansion and a hadronic threshold for decay products, we solve for a physical heavy quark decay width. It is shown that the charm (bottom) quark mass $m_c=1.35\mathrm{GeV}$ ($m_b=4.0\mathrm{GeV}$) can be determined by the dispersion relation for the $Q\to du\overline{d}$ ($Q\to c\overline{u}d$) decay with the threshold $2m_{\pi }$ ($m_{\pi }+m_D$), where $m_{\pi }$ ($m_D$) denotes the pion ($D$ meson) mass. Requiring that the dispersion relation for the $Q\to su\overline{d}$ ($Q\to d{\mu }^{+}{\nu }_{\mu }$, $Q\to u{\tau }^{-}{\overline{\nu }}_{\tau }$) decay with the threshold $m_{\pi }+m_K$ ($m_{\pi }+m_{\mu }$, $m_{\pi }+m_{\tau }$) yields the same heavy quark mass, $m_K$ being the kaon mass, we obtain the strange quark (muon, $\tau$ lepton) mass $m_s=0.12\mathrm{GeV}$ ($m_{\mu }=0.11\mathrm{GeV}$, $m_{\tau }=2.0\mathrm{GeV}$). Moreover, all the predicted decay widths corresponding to the above masses agree with the data. It is pointed out that our formalism is similar to QCD sum rules for probing resonance properties, and that the Pauli interference (weak annihilation) provides the higher-power effect necessary for establishing the solutions of the hadronic (semileptonic) decay widths. This work suggests that the parameters in the SM may not be free, but arranged properly to achieve internal dynamical consistency.

Analyses of the LHCb data on $X(6900)$ found in di-$J/\psi$ and $J/\psi \psi (3686)$ systems are performed using a momentum-dependent Flatté-like parametrization. The use of the pole-counting rule and spectral density function sum rule give consistent conclusions that $X(6900)$ may not be a molecule of $J/\psi \psi (3686)$. Nevertheless, it is still possible that $X(6900)$ is a molecule of higher states, such as $J/\psi \psi (3770)$, ${\chi }_{c0}{\chi }_{c2}$, etc.