We study the production of primordial circular (“V-mode”) polarization in axion inflation coupled to fermions and gauge fields, with special attention paid to (p)reheating. We construct the power spectrum of $V$, and find a blue-tilted spectrum with index $n_V=4$. This is independent of the dominant decay channel of the inflaton (direct fermion vs direct photon production).

We provide strong pieces of evidence that mathematics of three-dimensional hyperbolic manifolds of the first, second and third smallest volume are captured by the physics of three-dimensional theories composed of a complex boson and a Dirac fermion, both of a unit charge, coupled to a U(1) gauge field with the Chern-Simons levels $-5/2$, $-7/2$ and $-3/2$, respectively.

We realize a phenomenological study to examine the sensitivity on the magnetic moment and electric dipole moment of the top quark through the processes $\gamma \gamma \to t\overline{t}$, $e\gamma \to e{\gamma }^{*}\gamma \to et\overline{t}$, and $e^{-}{e}^{+}\to e^{-}{\gamma }^{*}{\gamma }^{*}{e}^{+}\to e^{-}t\overline{t}{e}^{+}$ at the Compact Linear Collider (CLIC). We find that with a center-of-mass energy of the CLIC-1.4 TeV, integrated luminosity of $\mathcal{L}=1500{\mathrm{fb}}^{-1}$ and CLIC-3 TeV, integrated luminosity of $\mathcal{L}=2000{\mathrm{fb}}^{-1}$ with systematic uncertainties of ${\delta }_{\mathrm{sys}}=0$, 5%, 10% at the 95% C.L., it is possible the CLIC may put limits on the electromagnetic dipole moments of the top quark ${\widehat{a}}_V$ and ${\widehat{a}}_A$ with a sensitivity of $\mathcal{O}({10}^{-3}-{10}^{-2})$. Therefore, we show that the sensitivity with the CLIC data is much greater than that for the Large Hadron Collider data.

The scale magnetic effect (SME) is the generation of electric current due to a conformal anomaly in an external magnetic field in curved spacetime. The effect appears in a vacuum with electrically charged massless particles. Similarly to the Hall effect, the direction of the induced anomalous current is perpendicular to the direction of the external magnetic field $\mathit{B}$ and to the gradient of the conformal factor $\tau$, while the strength of the current is proportional to the beta function of the theory. In massive electrodynamics the SME remains valid, but the value of the induced current differs from the current generated in the system of massless fermions. In the present paper we use the Wigner-Weyl formalism to demonstrate that in accordance with the decoupling property of heavy fermions the corresponding anomalous conductivity vanishes in the large-mass limit with $m^2\gg |e\mathit{B}|$ and $m\gg |\nabla \tau |$.

The factorization of amplitudes into hard, soft and collinear parts is known to be violated in situations where incoming particles are collinear to outgoing ones. This result was first derived by studying limits where noncollinear particles become collinear. We show that through an effective field theory framework with Glauber operators, these factorization-violating effects can be reproduced from an amplitude that is factorized before the splitting occurs. We confirm results at one loop, through single Glauber exchange, and at two loops, through double Glauber exchange. To approach the calculation, we begin by reviewing the importance of Glauber scaling for factorization. We show that for any situation where initial-state and final-state particles are not collinear, the Glauber contribution is entirely contained in the soft contribution. The contributions coming from Glauber operators are necessarily nonanalytic functions of external momentum, with the nonanalyticity arising from the rapidity regulator. The nonanalyticity is critical so that Glauber operators can both preserve factorization when it holds and produce factorization-violating effects when they are present.

We study the $ZH$ associated production followed by the Higgs $H\to \gamma \overline{\gamma }$ decay into a photon plus an invisible and massless dark photon, at future high-energy $e^{+}{e}^{-}$ facilities. Large $H\to \gamma \overline{\gamma }$ decay rates (with branching ratios up to a few percent) are allowed, thanks to possible nondecoupling properties of the Higgs boson under specific conditions, and unsuppressed dark-photon couplings in the dark sector. Such large decay rates can be obtained in the framework of recent flavor models that aim to naturally explain the observed spread in the fermion mass spectrum. We analyze the experimental prospects for observing the $e^{+}{e}^{-}\to ZH$ process followed by the semi-invisible Higgs decay into a photon plus a massless invisible system. Search strategies for both the leptonic and the hadronic final states (arising from $Z\to {\mu }^{+}{\mu }^{-}$ and $Z\to q\overline{q}$, respectively) are outlined. We find that a $5\sigma$ sensitivity to a branching fraction $B{R}_{\gamma \overline{\gamma }}\sim 3\times {10}^{-4}$ can be achieved by combining the two channels with an integrated luminosity of $10{\mathrm{ab}}^{-1}$ at a c.m. energy of 240 GeV. This is considerably better than the corresponding sensitivity in alternative channels previously studied at lepton colliders. The analysis is model independent, and its results can be straightforwardly applied to the search for any Higgs two-body decay into a photon plus an undetected light particle.

We attempt to understand the baryon-dark matter coincidence problem within the quark seesaw extension of the standard model where parity invariance is used to solve the strong $CP$ problem. The $SU(2{)}_L\times SU(2{)}_R\times U(1{)}_{B-L}$ gauge symmetry of this model is extended by a dark $U(1{)}_X$ group plus inclusion of a heavy neutral vector-like fermion ${\chi }_{L,R}$ charged under the dark group which plays the role of dark matter. All fermions are Dirac type in this model. Decay of heavy scalars charged under $U(1{)}_X$ leads to simultaneous asymmetry generation of the dark matter and baryons after sphaleron effects are included. The $U(1{)}_X$ group not only helps to stabilize the dark matter but also helps in the elimination of the symmetric part of the dark matter via $\chi -\overline{\chi }$ annihilation. For dark matter mass near the proton mass, it explains why the baryon and dark matter abundances are of similar magnitude (the baryon-dark matter coincidence problem). This model is testable in low threshold (sub-keV) direct dark matter search experiments.

We study tetraquark resonances with lattice QCD potentials computed for a static $\overline{b}\overline{b}$ pair in the presence of two lighter quarks $ud$, the Born-Oppenheimer approximation and the emergent wave method. As a proof of concept we focus on the system with isospin $I=0$, but consider different relative angular momenta $l$ of the heavy quarks $\overline{b}\overline{b}$. For $l=0$ a bound state has already been predicted with quantum numbers $I(J^P)=0(1^{+})$. Exploring various angular momenta we now compute the phase shifts and search for S and T matrix poles in the second Riemann sheet. We predict a tetraquark resonance for $l=1$, decaying into two $B$ mesons, with quantum numbers $I(J^P)=0(1^{-})$, mass $m=10576_{-4}^{+4}\mathrm{MeV}$ and decay width $\mathrm{\Gamma }=112_{-103}^{+90}\mathrm{MeV}$.

We interpret the new double charm baryon state found by the LHCb Collaboration in the invariant mass distribution of the set of final state particles $({\mathrm{\Lambda }}_c^{+}{K}^{-}{\pi }^{+}{\pi }^{+})$ as being at the origin of the decay chain ${\mathrm{\Xi }}_{cc}^{++}\to {\mathrm{\Sigma }}_c^{++}(\to {\mathrm{\Lambda }}_c^{+}{\pi }^{+})+{\overline{K}}^{*0}(\to K^{-}{\pi }^{+})$. The nonleptonic decay ${\mathrm{\Xi }}_{cc}^{++}\to {\mathrm{\Sigma }}_c^{++}+{\overline{K}}^{*0}$ belongs to a class of decays where the quark flavor composition is such that the decay proceeds solely via the factorizing contribution precluding a contamination from internal $W$-exchange. We use the covariant confined quark model previously developed by us to calculate the four helicity amplitudes that describe the dynamics of the transition ${\mathrm{\Xi }}_{cc}^{++}\to {\mathrm{\Sigma }}_c^{++}$ induced by the effective $(c\to u)$ current. We then proceed to calculate the rate of the decay as well as the polarization of the ${\mathrm{\Sigma }}_c^{++}$ and ${\mathrm{\Lambda }}_c^{+}$ baryons and the longitudinal/transverse composition of the ${\overline{K}}^{*0}$. We estimate the decay ${\mathrm{\Xi }}_{cc}^{++}\to {\mathrm{\Sigma }}_c^{++}{\overline{K}}^{*0}$ to have a branching rate of $B({\mathrm{\Xi }}_{cc}^{++}\to {\mathrm{\Sigma }}_c^{++}{\overline{K}}^{*0})\sim 10.5\%$. As a byproduct of our investigation we have also analyzed the decay ${\mathrm{\Xi }}_{cc}^{++}\to {\mathrm{\Sigma }}_c^{++}{\overline{K}}^0$ for which we find a branching ratio of $B({\mathrm{\Xi }}_{cc}^{++}\to {\mathrm{\Sigma }}_c^{++}{\overline{K}}^0)\sim 2.5\%$.

We work out the low-energy expansion of the anomalous $f_1(1285)\to \rho \gamma$ decay amplitude by using the Nambu–Jona-Lasinio model with $U(2)\times U(2)$ chiral symmetric four-quark interactions in the one-quark-loop approximation. The related processes $f_1(1285)\to \omega \gamma$, $a_1(1260)\to \omega \gamma$, and $a_1(1260)\to \rho \gamma$, are also considered. An effective meson Lagrangian responsible for $f_1\rho \gamma$, $f_1\omega \gamma$, $a_1\rho \gamma$ and $a_1\omega \gamma$ interactions is found. The predicted radiative decay widths, ${\mathrm{\Gamma }}_{f_1\to {\rho }^0\gamma }=311\mathrm{keV}$, ${\mathrm{\Gamma }}_{f_1\to \omega \gamma }=34.3\mathrm{keV}$, ${\mathrm{\Gamma }}_{a_1\to {\rho }^0\gamma }=26.8\mathrm{keV}$, ${\mathrm{\Gamma }}_{a_1\to \omega \gamma }=238\mathrm{keV}$, allow an experimental test of the hypothesis that $f_1(1285)$ and $a_1(1260)$-mesons have a quark-antiquark nature. At present, only the $f_1(1285)\to \rho \gamma$ decay has been measured. Our result is in remarkably good agreement with the recent data of CLAS Collaboration ${\mathrm{\Gamma }}_{f_1\to {\rho }^0\gamma }=453\pm 177\mathrm{keV}$, but disagrees with the Particle Data Group-based estimate of ${\mathrm{\Gamma }}_{f_1\to {\rho }^0\gamma }=1326\pm 313\mathrm{keV}$. The calculations presented require a minimum of theoretical input, and are shown to be consistent with the nonrenormalization theorems of QCD.

We derive an approximate analytical formula for the spectral density of the $q$-body Sachdev-Ye-Kitaev (SYK) model obtained by summing a class of diagrams representing leading intersecting contractions. This expression agrees with that of $Q$-Hermite polynomials, with $Q$ a nontrivial function of $q\ge 2$ and the number of Majorana fermions $N$. Numerical results, obtained by exact diagonalization, are in excellent agreement with this approximate analytical spectral density even for relatively small $N\sim 8$. For $N\gg 1$ and not close to the edge of the spectrum, we find that the approximate analytical spectral density simplifies to ${\rho }_{\mathrm{asym}}(E)=\exp [2{\arcsin }^2(E/E_0)/\log \eta ]$, where $\eta (N,q)$ is the suppression factor of the contribution of intersecting Wick contractions relative to nested contractions and $E_0$ is the ground-state energy per particle. This spectral density reproduces the known result for the free energy in the large-$q$ and large-$N$ limit at arbitrary values of the temperature. In the infrared region, where the SYK model is believed to have a gravity dual, the analytical spectral density is given by $\rho (E)\sim \sinh [2\pi \sqrt{2}\sqrt{(1-E/E_0)/(-\log \eta )}]$. It therefore has a square-root edge, as in random matrix ensembles, followed by an exponential growth, a distinctive feature of black holes and also of low-energy nuclear excitations. Results for level statistics in this region confirm the agreement with random matrix theory. Physically this is a signature that, for sufficiently long times, the SYK model and its gravity dual evolve to a fully ergodic state whose dynamics only depends on the global symmetry of the system. Our results strongly suggest that random matrix correlations are a universal feature of quantum black holes and that the SYK model, combined with holography, may be relevant to modeling certain aspects of the nuclear dynamics.

The behavior of a massive charged test Dirac field in the background of a Reissner-Nordström black hole is investigated. Especially, we obtain the frequencies of quasibound states by solving the Dirac equation numerically both in time and frequency domain. Our results suggest that although the absence of superradiance excludes the existence of stationary solutions for massive Dirac fields, it is still possible to find arbitrarily long-lived solutions.

Simulation and experimental realization of acoustic black holes in analogue gravity systems have lead to a novel understanding of relevant phenomena such as Hawking radiation or superradiance. We explore here the possibility of using relativistic systems for simulating rotating black hole solutions and possibly get an acoustic analogue of a Kerr black hole. In doing so, we demonstrate a precise relation between nonrelativistic and relativistic solutions and provide a new class of vortex solutions for relativistic systems. Such solutions might be used in the future as a test bed in numerical simulations as well as concrete experiments.

The “gravitational memory effect” due to an exact plane wave provides us with an elementary description of the diffeomorphisms associated with the analogue of “soft gravitons for this nonasymptotically flat system. We explain how the presence of the latter may be detected by observing the motion of freely falling particles or other forms of gravitational wave detection. Numerical calculations confirm the relevance of the first, second and third time integrals of the Riemann tensor pointed out earlier. Solutions for various profiles are constructed. It is also shown how to extend our treatment to Einstein-Maxwell plane waves and a midisuperspace quantization is given.

In this work we present an analytical gravitational self-force calculation of the spin-orbit precession along an eccentric orbit around a Schwarzschild black hole, following closely the recent prescription of Akcay, Dempsey, and Dolan, giving results to six post-Newtonian orders expanded in small eccentricity through $e^2$. We then transcribe this quantity within the effective-one-body (EOB) formalism, thereby determining several new, linear-in-mass-ratio contributions in the post-Newtonian expansion of the spin-orbit couplings entering the EOB Hamiltonian. Namely, we determine the second gyrogravitomagnetic ratio $g_{S_{*}}(r,p_r,p_{\varphi })$ up to order $p_r^2/r^4$ included.

Force-free electrodynamics (FFE) describes a particular regime of magnetically dominated relativistic plasmas, which arises on several astrophysical scenarios of interest such as pulsars or active galactic nuclei. In this article, we present a full 3D numerical implementation of the FFE evolution around a Kerr black hole. The novelty of our approach is three-folded: (i) We use the “multiblock” technique [L. Lehner, O. Reula, and M.Tiglio, Multi-block simulations in general relativity: High-order discretizations, numerical stability and applications, Classical Quantum Gravity 22, 5283 (2005).] to represent a domain with $S^2\times {\mathbb{R}}^{+}$ topology within a stable finite-differences scheme. (ii) We employ as evolution equations those arising from a covariant hyperbolization of the FFE system [F. Carrasco and O. Reula, Covariant hyperbolization of force-free electrodynamics, Phys. Rev. D 93, 085013 (2016).]. (iii) We implement stable and constraint-preserving boundary conditions to represent an outer region given by a uniform magnetic field aligned or misaligned respect to the symmetry axis. The construction of appropriate and consistent boundary conditions, both preserving the constraints and physically immersing the system in a uniform magnetic field, has allowed us to obtain long-term stationary solutions representing jets of astrophysical relevance. These numerical solutions are shown to be consistent with previous studies.

The gravitational-wave (GW) asteroseismology is a powerful technique for extracting interior information of compact objects. In this work, we focus on spacetime modes, the so-called $w$ modes, of GWs emitted from a proto-neutron star (PNS) in the postbounce phase of core-collapse supernovae. Using results from recent three-dimensional supernova models, we study how to infer the properties of the PNS based on a quasi-normal mode analysis in the context of the GW asteroseismology. We find that the $w_1$-mode frequency multiplied by the PNS radius is expressed as a linear function with respect to the ratio of the PNS mass to the PNS radius. This relation is insensitive to the nuclear equation of state (EOS) employed in this work. Combining with another universal relation of the $f$-mode oscillations, we point out that the time dependent mass-radius relation of the PNS can be obtained by observing both the $f$- and $w_1$-mode GWs simultaneously. Our results suggest that the simultaneous detection of the two modes could provide a new probe into finite-temperature nuclear EOS that predominantly determines the PNS evolution.

Continuous gravitational waves from neutron stars could provide an invaluable resource to learn about their interior physics. A common search method involves matched filtering a modeled template against the noisy gravitational-wave data to find signals. This method suffers a mismatch (i.e., relative loss of the signal-to-noise ratio) if the signal deviates from the template. One possible instance in which this may occur is if the neutron star undergoes a glitch, a sudden rapid increase in the rotation frequency seen in the timing of many radio pulsars. In this work, we use a statistical characterization of the glitch rate and size in radio pulsars to estimate how often neutron star glitches would occur within the parameter space of continuous gravitational-wave searches and how much mismatch putative signals would suffer in the search due to these glitches. We find that for many previous and potential future searches continuous-wave signals have an elevated probability of undergoing one or more glitches and that these glitches will often lead to a substantial fraction of the signal-to-noise ratio being lost. This could lead to a failure to identify candidate gravitational-wave signals in the initial stages of a search and also to the false dismissal of candidates in subsequent follow-up stages.

The flux of very high-energy neutrinos produced in our Galaxy by the interaction of accelerated cosmic rays with the interstellar medium is not yet determined. The characterization of this flux will shed light on Galactic accelerator features, gas distribution morphology and Galactic cosmic ray transport. The central Galactic plane can be the site of an enhanced neutrino production, thus leading to anisotropies in the extraterrestrial neutrino signal as measured by the IceCube Collaboration. The ANTARES neutrino telescope, located in the Mediterranean Sea, offers a favorable view of this part of the sky, thereby allowing for a contribution to the determination of this flux. The expected diffuse Galactic neutrino emission can be obtained, linking a model of generation and propagation of cosmic rays with the morphology of the gas distribution in the Milky Way. In this paper, the so-called “gamma model” introduced recently to explain the high-energy gamma-ray diffuse Galactic emission is assumed as reference. The neutrino flux predicted by the “gamma model” depends on the assumed primary cosmic ray spectrum cutoff. Considering a radially dependent diffusion coefficient, this proposed scenario is able to account for the local cosmic ray measurements, as well as for the Galactic gamma-ray observations. Nine years of ANTARES data are used in this work to search for a possible Galactic contribution according to this scenario. All flavor neutrino interactions are considered. No excess of events is observed, and an upper limit is set on the neutrino flux of 1.1 (1.2) times the prediction of the “gamma model,” assuming the primary cosmic ray spectrum cutoff at 5 (50) PeV. This limit excludes the diffuse Galactic neutrino emission as the major cause of the “spectral anomaly” between the two hemispheres measured by IceCube.