Massive black hole binaries are expected to provide the strongest gravitational wave signals for the Laser Interferometer Space Antenna (LISA), a space mission targeting $\sim \mathrm{mHz}$ frequencies. As a result of the technological challenges inherent in the mission’s design, implementation, and long duration (4 yr nominal), the LISA data stream is expected to be affected by relatively long gaps where no data is collected (either because of hardware failures, or because of scheduled maintenance operations, such as repointing of the antennas toward the Earth). Depending on their mass, massive black hole binary signals may range from quasitransient to very long lived, and it is unclear how data gaps will impact detection and parameter estimation of these sources. Here, we will explore this question by using state-of-the-art astrophysical models for the population of massive black hole binaries. We will investigate the potential detectability of massive black hole binary signals by observing the effect of gaps on their signal-to-noise ratios. We will also assess the effect of the gaps on parameter estimation for these sources, using the Fisher information matrix formalism as well as full Bayesian analyses. Overall, we find that the effect of data gaps due to regular maintenance of the spacecraft is negligible, except for systems that coalesce within such a gap. The effect of unscheduled gaps, however, will probably be more significant than that of scheduled ones.

While the Kerr-Schild double copy of the Coulomb solution in dimensions higher than three is the Schwarzschild black hole, it is known that it should be a nonvacuum solution in three dimensions. We show that the static black hole solution of Einstein-Maxwell theory (with one ghost sign in the action) is the double copy with the correct Newtonian limit, which provides an improvement over the previous construction with a free scalar field that does not vanish at infinity. By considering a negative cosmological constant, we also study the charged Bañados-Teitelboim-Zanelli black hole and find that the single copy gauge field is the Coulomb solution modified by a term which describes an electric field linearly increasing with the radial coordinate, which is the usual behavior of the Schwarzschild-AdS black hole in higher dimensions when written around a flat background metric.

Time-delay interferometry (TDI) is the data processing technique that cancels the large laser phase fluctuations affecting the one-way Doppler measurements made by unequal-arm space-based gravitational wave interferometers. By taking finite linear combinations of properly time-shifted Doppler measurements, laser phase fluctuations are removed at any time $t$ and gravitational wave signals can be studied at a requisite level of precision. In this article we show the delay operators used in TDI can be represented as matrices acting on arrays associated with the laser noises and Doppler measurements. The matrix formulation is nothing but the group theoretic representation (ring homomorphism) of the earlier approach involving time-delay operators and so in principle is the same. It is shown that the homomorphism is valid generally and we cover all situations of interest. To understand the potential advantages the matrix representation brings, care must be taken by the data analyst to account for the light travel times when linearly relating the one-way Doppler measurements to the laser noises. This is especially important in view of the future gravitational wave projects envisaged. We show that the matrix formulation of TDI results in the cancellation of the laser noises at an arbitrary time $t$ by only linearly combining a finite number of samples of the one-way Doppler data measured at and around time $t$.

We consider warm inflation with a Dirac-Born-Infeld (DBI) kinetic term in which both the nonequilibrium dissipative particle production and the sound speed parameter slow the motion of the inflaton field. We find that a low sound speed parameter removes, or at least strongly suppresses, the growing function appearing in the scalar of curvature power spectrum of warm inflation, which appears due to the temperature dependence in the dissipation coefficient. As a consequence of that, a low sound speed helps to push warm inflation into the strong dissipation regime, which is an attractive regime from a model building and phenomenological perspective. In turn, the strong dissipation regime of warm inflation softens the microscopic theoretical constraints on cold DBI inflation. The present findings, along with the recent results from swampland criteria, give a strong hint that warm inflation may consistently be embedded into string theory.

The baryon acoustic oscillations (BAO) have proven to be an invaluable tool in constraining the expansion history of the Universe at late times and are characterized by the comoving sound horizon at the baryon drag epoch $r_{\mathrm{s}}(z_{\mathrm{d}})$. The latter quantity can be calculated either numerically using recombination codes or via fitting functions, such as the one by Eisenstein and Hu, made via grids of parameters of the recombination history. Here we quantify the accuracy of these expressions and show that they can strongly bias the derived constraints on the cosmological parameters using BAO data. Then, using a machine learning approach, called the genetic algorithms, we proceed to derive new analytic expressions for $r_{\mathrm{s}}(z_{\mathrm{d}})$, which are accurate at the $\sim 0.003\%$ level in a range of $10\sigma$ around the Planck 2018 best fit or $\sim 0.018\%$ in a much broader range, compared to $\sim 2–4\%$ for the Eisenstein and Hu expression, thus obtaining an improvement of two to three orders of magnitude. Moreover, we also provide fits that include the effects of massive neutrinos and an extension to the concordance cosmological model assuming variations of the fine structure constant. Finally, we note that our expressions can be used to ease the computational cost required to compute $r_{\mathrm{s}}(z_{\mathrm{d}})$ with a Boltzmann code when deriving cosmological constraints using BAO data from current and upcoming surveys.

We study the decay of cosmic string loops in the Abelian-Higgs model. We confirm earlier results that loops formed by intersections of infinite strings formed from random-field initial conditions disappear quickly, with lifetimes proportional to their initial rest-frame length, ${\ell }_{\mathrm{init}}$. We study a population with ${\ell }_{\mathrm{init}}$ up to 6000 inverse mass units and measure the proportionality constant to be $0.14\pm 0.04$, independently of the initial lengths. We propose a new method to construct oscillating nonself intersecting loops from initially stationary strings and show that by contrast these loops have lifetimes scaling approximately as ${\ell }_{\mathrm{init}}^2$, in line with previous works on artificially created string configurations. We show that the oscillating strings have a mean-square velocity of ${\overline{v}}^2\simeq 0.500\pm 0.004$, consistent with the Nambu-Goto value of $1/2$, while the network loops have ${\overline{v}}^2\simeq 0.40\pm 0.04$. We argue that whatever the mechanism behind the network loop decay is, it is nonlinear, can only be suppressed by careful tuning of initial conditions, and is much stronger than gravitational radiation. An implication is that one cannot use the Nambu-Goto model to derive robust constraints on the tension of field theory strings. We advocate parametrizing the uncertainty as the fraction $f_{\mathrm{NG}}$ of Nambu-Goto-like loops surviving to radiate gravitationally. None of the 31 large network loops created survived longer than 0.25 of their initial length, so one can estimate that $f_{\mathrm{NG}}<0.1$ at 95% confidence level. If the recently reported NANOgrav signal is due to cosmic strings, $f_{\mathrm{NG}}$ must be greater than ${10}^{-3}$ in order not to violate bounds from the cosmic microwave background.

The kinematic Sunyaev-Zel’dovich (kSZ) effect—the Doppler boosting of Cosmic Microwave Background (CMB) photons scattering off free electrons with nonzero line-of-sight velocity—is an excellent probe of the distribution of baryons in the Universe. In this paper, we measure the kSZ effect due to ionized gas traced by infrared-selected galaxies from the $unWISE$ catalog. We employ the “projected-field” kSZ estimator, which does not require spectroscopic galaxy redshifts. To suppress contributions from non-kSZ signals associated with the galaxies (e.g., dust emission and thermal SZ), this estimator requires foreground-cleaned CMB maps, which we obtain from $Planck$ and $WMAP$ data. Using a new “asymmetric” estimator that combines different foreground-cleaned CMB maps to maximize the signal-to-noise, we measure the ${\mathrm{kSZ}}^2$-galaxy cross-power spectrum for three subsamples of the $unWISE$ galaxy catalog. These subsamples peak at mean redshifts $z\approx 0.6$, 1.1, and 1.5, have average halo mass $\sim 1–5\times {10}^{13}{h}^{-1}{M}_{\odot }$, and in total contain over 500 million galaxies. After marginalizing over contributions from CMB lensing, we measure the amplitude of the kSZ signal $A_{{\mathrm{kSZ}}^2}=0.42\pm 0.31(\mathrm{stat})\pm 0.02(\mathrm{sys})$, $5.02\pm 1.01(\mathrm{stat})\pm 0.49(\mathrm{sys})$, and $8.23\pm 3.23(\mathrm{stat})\pm 0.57(\mathrm{sys})$, for the three subsamples, where $A_{{\mathrm{kSZ}}^2}=1$ corresponds to our fiducial theoretical model. The combined statistical significance of our kSZ detection exceeds $5\sigma$. Our theoretical model includes the first calculation of lensing magnification contributions to the ${\mathrm{kSZ}}^2$-galaxy cross-power spectrum, which are significant for the $z\approx 1.1$ and 1.5 subsamples. We discuss possible explanations for the excess kSZ signal associated with the $z\approx 1.1$ sample, and show that foreground contamination in the CMB maps is very unlikely to be the cause. From our measurements of $A_{{\mathrm{kSZ}}^2}$, we constrain the product of the baryon fraction $f_b$ and free electron fraction $f_{\mathrm{free}}$ to be $(f_b/0.158)(f_{\mathrm{free}}/1.0)=0.65\pm 0.24$, $2.24\pm 0.25$, and $2.87\pm 0.57$ at $z\approx 0.6$, 1.1, and 1.5, respectively, consistent with a large fraction of the cosmic baryon abundance existing in an ionized state at low redshifts.

We extend the effective field theory (EFT) formalism for gravitational radiation from a binary system of compact objects to the case of extended objects. In particular, we study the EFT for a binary system consisting of two infinitely-long cosmic strings with small velocity and small spatial substructure, or “wiggles.” The complexity of the system requires the introduction of two perturbative expansion parameters, constructed from the velocity and size of the wiggles, in contrast with the point particle case, for which a single parameter is sufficient. This further requires us to assign new power counting rules in the system. We integrate out the modes corresponding to potential gravitons, yielding an effective action for the radiation gravitons and obtaining the effective potential between the cosmic strings. We show that this action describes a changing quadrupole, sourced by the bending modes of the string, which in turn generates gravitational waves. We study the ultraviolet divergences in this description, and use them to obtain the classical renormalization group flow of the string tension in such a setting.

We investigate the potential of type II supernovae (SNe) to constrain axionlike particles (ALPs) coupled simultaneously to nucleons and electrons. ALPs coupled to nucleons can be efficiently produced in the SN core via nucleon-nucleon bremsstrahlung and, for a wide range of parameters, leave the SN unhindered, producing a large ALP flux. For masses exceeding 1 MeV, these ALPs would decay into electron-positron pairs, generating a positron flux. In the case of Galactic SNe, the annihilation of the created positrons with the electrons present in the Galaxy would contribute to the 511 keV annihilation line. Using the spectrometer on integral observation of this line allows us to exclude a wide range of the axion-electron coupling, ${10}^{-19}\lesssim g_{ae}\lesssim {10}^{-11}$, for $g_{ap}\sim {10}^{-9}$. Additionally, ALPs from extra-galactic SNe decaying into electron-positron pairs would yield a contribution to the cosmic x-ray background. In this case, we constrain the ALP-electron coupling down to $g_{ae}\sim {10}^{-20}$.

The Einstein Telescope (ET) is the future third generation gravitational wave detector consisting of three independent interferometers arranged in a triangular configuration, with the sensitivity large enough to be able to detect stellar mass black holes even beyond the redshift of 10. In this paper, we analyze the capabilities of ET as a standalone instrument and not part of a network. We show that the analysis of detection of binary coalescences in the three individual interferometers of the ET allow us to weakly constrain the sky location of the source. We present the analysis that leads to the constraints on the redshift and source frame chirp mass of detected binaries. We show that these values can be estimated with the accuracy comparable to the one expected from networks of gravitational wave interferometers. Thus, we show that the ET as a single instrument is able to break the redshift—chirp mass degeneracy and is therefore a valuable tool to explore properties of populations of merging compact object binaries.

Terrestrial gamma-ray flashes (TGFs) are powerful submillisecond bursts of gamma rays produced by thunderstorms. To date, most TGFs have been observed by spacecraft in low-Earth orbit and have been found to be associated with negative intracloud lightning leaders. In recent years, TGFs have also been measured on the ground as downward beams originating from the overhead storms. While the majority of these ground-level TGFs appear to be associated with negative lightning leaders, similar to the TGFs seen from space, others are associated with upward-propagating positive leaders. In this paper, Runaway Electron Avalanche Model Monte Carlo simulations, modified to include low-energy electron and ion currents and self-consistent electric fields, are used to model TGF production by the relativistic feedback mechanism initiated by positive leaders. It is found that intense bursts of gamma rays are produced by positive leaders, similar to the observed ground-level TGFs. It is also found that these events produce dangerous radiation doses in excess of 1 Sievert and so may be of concern for aviation safety.

We relate the fundamental quadrupolar fluid mode of isolated nonrotating neutron stars (NSs) and the dominant oscillation frequency of neutron star merger remnants. Both frequencies individually are known to correlate with certain stellar parameters like radii or the tidal deformability, which we further investigate by constructing fit formulas and quantifying the scatter of the data points from those relations. Furthermore, we compare how individual data points deviate from the corresponding fit to all data points. Considering this point-to-point scatter we uncover a striking similarity between the frequency deviations of perturbative data for isolated NSs and of oscillation frequencies of rapidly rotating, hot, massive merger remnants. The correspondence of frequency deviations in these very different stellar systems points to an underlying mechanism and equation of state information being encoded in the frequency deviation. We trace the frequency scatter back to deviations of the tidal Love number from an average tidal Love number for a given stellar compactness. Our results thus indicate a possibility to break the degeneracy between NS radii, tidal deformability, and tidal Love number. We also relate frequency deviations to the derivative of the tidal deformability with respect to mass. Our findings generally highlight a possibility to improve gravitational wave (GW) asteroseismology relations where the systematic behavior of frequency deviations is employed to reduce the scatter in such relationships and consequently increase the measurement accuracy. In addition, we relate the $f$-mode frequency of static stars and the dominant GW frequency of merger remnants. We find an analytic mapping to connect the masses of both stellar systems, which yields particularly accurate mass-independent relations between both frequencies and between the postmerger frequency and the tidal deformability.

The ’t Hooft model, i.e., the two-dimensional quantum chromodynamics in the limit of infinite number of colors, is interpolated by an angle parameter $\delta$ between $\delta =0$ for the instant form dynamics (IFD) and $\delta =\pi /4$ for the light-front dynamics (LFD). With this parameter $\delta$, we formulate the interpolating mass gap equation which takes into account the nontrivial vacuum effect on the bare fermion mass to find the dressed fermion mass. Our interpolating mass gap solutions not only reproduce the previous IFD result at $\delta =0$ as well as the previous LFD result at $\delta =\pi /4$ but also link them together between the IFD and LFD results with the $\delta$ parameter. We find the interpolation angle independent characteristic energy function which satisfies the energy-momentum dispersion relation of the dressed fermion, identifying the renormalized fermion mass function and the wave function renormalization factor. The renormalized fermion condensate is also found independent of $\delta$, indicating the persistence of the nontrivial vacuum structure even in the LFD. Using the dressed fermion propagator interpolating between IFD and LFD, we derive the corresponding quark-antiquark bound-state equation in the interpolating formulation verifying its agreement with the previous bound-state equations in the IFD and LFD at $\delta =0$ and $\delta =\pi /4$, respectively. The mass spectra of mesons bearing the feature of the Regge trajectories are found independent of the $\delta$-parameter reproducing the previous results in LFD and IFD for the equal mass quark and antiquark bound states. The Gell-Mann-Oakes-Renner relation for the pionic ground-state in the zero fermion mass limit is confirmed indicating that the spontaneous breaking of the chiral symmetry occurs in the ’t Hooft model regardless of the quantization for $0\le \delta \le \pi /4$. We obtain the corresponding bound-state wave functions and discuss their reference frame dependence with respect to the frame independent LFD result. Applying them for the computation of the so-called quasi-parton distribution functions now in the interpolating formulation between IFD and LFD, we note a possibility of utilizing not only the reference frame dependence but also the interpolation angle dependence to get an alternative effective approach to the LFD-like results.

The $U_1$ leptoquark is known to be a suitable candidate for explaining the semileptonic $B$-decay anomalies. We derive precise limits on its parameter space relevant for the anomalies from the current LHC high-$p_{\mathrm{T}}$ dilepton data. We consider an exhaustive list of possible $B$-anomalies-motivated simple scenarios with one or two new couplings that can also be used as templates for obtaining bounds on more complicated scenarios. To obtain precise limits, we systematically consider all possible $U_1$ production processes that can contribute to the dilepton searches, including the resonant pair and single productions, nonresonant $t$-channel $U_1$ exchange, as well as its large interference with the Standard Model background. We demonstrate how the inclusion of resonant production contributions in the dilepton signal can lead to appreciably improved exclusion limits. We point out new search channels of $U_1$ that can act as unique tests of the flavor-motivated models. The template scenarios can also be used for future $U_1$ searches at the LHC. We compare the LHC limits with other relevant flavor bounds and find that a TeV-scale $U_1$ can accommodate both $R_{D^{(*)}}$ and $R_{K^{(*)}}$ anomalies while satisfying all the bounds.

In this paper, we investigate the contributions of anomalous quartic gauge couplings (aQGCs) to $Z\gamma jj$ production at the Large Hadron Collider in the context of Standard Model effective theory (SMEFT). When the energy scale is large, the validity of SMEFT becomes an important issue. To ensure the validity, the unitarity bound is applied in a model independent approach, which is found to have significant suppressive effects on the signals of $O_{M_i}$ operators. The kinematic and polarization features of the aQGC signals are also studied. The polarization effect is useful to highlight the signals of $O_{T_i}$ operators. The sensitivity estimates on dimension-8 operators with unitarity bounds at $\sqrt{s}=14\mathrm{TeV}$ are obtained.

We identify what may be the world’s most sensitive location to search for millicharged particles in the 10 MeV to 100 GeV mass range: the forward region at the LHC. We propose constructing a scintillator-based experiment, FORward MicrOcharge SeArch (FORMOSA) in this location. FORMOSA can discover millicharged particles in a large and unexplored region of parameter space, including millicharged strongly interacting dark matter (mSIDM) candidates that cannot be probed by ground-based direct-detection experiments. The newly proposed LHC Forward Physics Facility (FPF) provides an ideal structure to host the full FORMOSA experiment.

We study electroweak symmetry breaking in minimal composite Higgs models $SU(4)/Sp(4)$ with purely fermionic UV completions based on a confining hypercolor gauge group and find that the extra Higgs potential from the underlying preon mass can destruct the correlation between the mass of Higgs and composite partners. Thus, the composite partners can be very heavy for successful electroweak symmetry breaking without enhancing the separation between the new physical scale and Higgs vacuum expectation value. So this kind of model can be easily realized by ordinary strong dynamics theories without artificial assumptions and, more likely, consistent with lattice simulations. The UV completion of partial compositeness predicts a light singlet Goldstone boson, which interacts with QCD and electroweak gauge bosons through Wess-Zumino-Witten terms. It can be produced through gluon fusion at LHC and decay into gauge boson pairs. We briefly discuss its phenomenology and derive its bounds from LHC searches.

A pseudo-Nambu-Goldstone boson (pNGB) is an attractive candidate for dark matter (DM) due to the simple evasion of the current severe limits of DM direct detection experiments. One of the pNGB DM models has been proposed based on a gauged $U(1{)}_{B-L}$ symmetry. The pNGB has long enough lifetime to be a DM and thermal relic abundance of pNGB DM can be fit with the observed value against the constraints on the DM decays from the cosmic-ray observations. The pNGB DM model can be embedded into an $SO(10)$ pNGB DM model in the framework of an $SO(10)$ grand unified theory, whose $SO(10)$ is broken to the Pati-Salam gauge group at the unified scale, and further to the Standard Model gauge group at the intermediate scale. Unlike the previous pNGB DM model, the parameters such as the gauge coupling constants of $U(1{)}_{B-L}$, the kinetic mixing parameter of between $U(1{)}_Y$ and $U(1{)}_{B-L}$ are determined by solving the renormalization group equations for gauge coupling constants with appropriate matching conditions. From the constraints of the DM lifetime and gamma-ray observations, the pNGB DM mass must be less than $\mathcal{O}(100)\mathrm{GeV}$. We find that the thermal relic abundance can be consistent with all the constraints when the DM mass is close to half of the $CP$ even Higgs masses.