The stellar binary $\eta$ Carinae has been observed during its full orbital period in gamma rays by the Fermi-Large Area Telescope (LAT). The shock-accelerated electrons in the colliding winds of the two stars radiate synchrotron photons in the magnetic field of the shocked region and inverse Compton photons, where the target photons are from the thermal emissions by the more massive and luminous of the two stars. The inverse Compton emission dominates the gamma-ray flux data from the $\eta$ Carinae, however the spectral energy distribution shows signature of a hadronic component in the $\sim 10–300\mathrm{GeV}$ range during the periastron passage. Current and future air Cherenkov telescopes will be able to constrain this component at TeV energies. Acceleration of cosmic-ray protons to $\gg 1\mathrm{TeV}$ energies in the colliding winds, required to explain the hadronic emission component through photopion interactions, can lead to detectable signal of $\gtrsim 10\mathrm{TeV}$ neutrino events in large kilometer scale neutrino telescopes.

Pulsar timing arrays (PTAs) are used to search for long-wavelength gravitational waves (GWs) by monitoring a set of spin-stable millisecond pulsars. Most theoretical analyses assume that the relevant GW sources are much more distant from Earth than the pulsars comprising the array. Unlike ground- or solar system-based GW detectors, PTAs might well contain embedded GW sources. We derive the PTA response from sources at any distance, with a specific focus on GW bursts with memory (BWM). We consider supernovae and compact binary mergers as potential Galactic BWM sources and evaluate the signature for an array with pulsars in globular clusters or in the Galactic center. Understanding the response of PTAs to nearby sources of BWM is a step toward investigating other more complex Galactic sources.

The remnant of neutron star mergers is dense in neutrinos. By employing inputs from one hydrodynamical simulation of a binary neutron star merger remnant with a black hole of $3M_{\odot }$ in the center, dimensionless spin parameter 0.8 and an accretion torus of $0.3M_{\odot }$, the neutrino emission properties are investigated as the merger remnant evolves. Initially, the local number density of ${\overline{\nu }}_e$ is larger than that of ${\nu }_e$ everywhere above the remnant. Then, as the torus approaches self-regulated equilibrium, the local abundance of neutrinos overcomes that of antineutrinos in a funnel around the polar region. The region where the fast pairwise flavor conversions can occur shrinks accordingly as time evolves. Still, we find that fast flavor conversions do affect most of the neutrino-driven ejecta. Assuming that fast flavor conversions lead to flavor equilibration, a significant enhancement of nuclei with mass numbers $A>130$ is found as well as a change of the lanthanide mass fraction by more than a factor of a thousand. Our findings hint towards a potentially relevant role of neutrino flavor oscillations for the prediction of the kilonova (macronova) light curves and motivate further work in this direction.

We present a framework linking axionlike particles (ALPs) to neutrino masses through the minimal inverse seesaw (ISS) mechanism in order to explain the dark matter (DM) puzzle. Specifically, we explore three minimal ISS cases where mass scales are generated through gravity-induced operators involving a scalar field hosting ALPs. In all of these cases, we find gravity-stable models that provide the observed DM relic density and, simultaneously, are consistent with the phenomenology of neutrinos and ALPs. Remarkably, in one of the ISS cases, the DM can be made of ALPs and sterile neutrinos. Furthermore, other considered ISS cases have ALPs with parameters that are within the reach of proposed ALP experiments.

We explore lepton-flavored electroweak baryogenesis, driven by $CP$-violation in leptonic Yukawa sector, using the $\tau -\mu$ system in the two Higgs doublet model as an example. This setup generically yields, together with the flavor-changing decay $h\to \tau \mu$, a tree-level Jarlskog invariant that can drive dynamical generation of baryon asymmetry during a first-order electroweak phase transition and results in $CP$-violating effects in the decay $h\to \tau \tau$. We find that the observed baryon asymmetry can be generated in parameter space compatible with current experimental results for the decays $h\to \tau \mu$, $h\to \tau \tau$, and $\tau \to \mu \gamma$, as well as the present bound on the electric dipole moment of the electron. The baryon asymmetry generated is intrinsically correlated with the $CP$-violating decay $h\to \tau \tau$ and the flavor-changing decay $h\to \tau \mu$, which thus may serve as “smoking guns” to test lepton-flavored electroweak baryogenesis.

We develop numerical tools for diagrammatic Monte Carlo simulations of non-Abelian lattice field theories in the t’Hooft large-$N$ limit based on the weak-coupling expansion. First, we note that the path integral measure of such theories contributes a bare mass term in the effective action which is proportional to the bare coupling constant. This mass term renders the perturbative expansion infrared-finite and allows us to study it directly in the large-$N$ and infinite-volume limits using the diagrammatic Monte Carlo approach. On the exactly solvable example of a large-$N$ $O(N)$ sigma model in $D=2$ dimensions we show that this infrared-finite weak-coupling expansion contains, in addition to powers of bare coupling, also powers of its logarithm, reminiscent of resummed perturbation theory in thermal field theory and resurgent trans-series without exponential terms. We numerically demonstrate the convergence of these double series to the manifestly nonperturbative dynamical mass gap. We then develop a diagrammatic Monte Carlo algorithm for sampling planar diagrams in the large-$N$ matrix field theory, and apply it to study this infrared-finite weak-coupling expansion for large-$N$ $U(N)\times U(N)$ nonlinear sigma model (principal chiral model) in $D=2$. We sample up to 12 leading orders of the weak-coupling expansion, which is the practical limit set by the increasingly strong sign problem at high orders. Comparing diagrammatic Monte Carlo with conventional Monte Carlo simulations extrapolated to infinite $N$, we find a good agreement for the energy density as well as for the critical temperature of the “deconfinement” transition. Finally, we comment on the applicability of our approach to planar QCD at zero and finite density.

We reexamine the relations between the Bethe-Salpeter (BS) wave function of two particles, the on-shell scattering amplitude, and the effective potential in quantum filed theory. It is emphasized that there is an exact relation between the BS wave function inside the interaction range and the scattering amplitude, and the reduced BS wave function, which is defined in this article, plays an essential role in this relation. Based on the exact relation, we show that the solution of Schrödinger equation with the effective potential gives us a correct on-shell scattering amplitude only at the momentum where the effective potential is calculated, while wrong results are obtained from the Schrödinger equation at general momenta. We also discuss about a momentum expansion of the reduced BS wave function and an uncertainty of the scattering amplitude stemming from the choice of the interpolating operator in the BS wave function. The theoretical conclusion obtained in this article could give hints to understand the inconsistency observed in lattice QCD calculation of the two-nucleon channels with different approaches.

In this paper, we investigate the hidden-charm pentaquarks as ${\overline{D}}^{(*)}{\mathrm{\Lambda }}_{\mathrm{c}}$ and ${\overline{D}}^{(*)}{\mathrm{\Sigma }}_{\mathrm{c}}^{(*)}$ molecules coupled to the five-quark states. Furthermore, we extend our calculations to the hidden-bottom sector. The coupling to the five-quark states is treated as the short range potential, where the relative strength for the meson-baryon channels is determined by the structure of the five-quark states. We found that resonant and/or bound states appear in both the charm and bottom sectors. The five-quark state potential turned out to be attractive and, for this reason, it plays an important role to produce these states. In the charm sector, we need the five-quark potential in addition to the pion exchange potential in producing bound and resonant states, whereas, in the bottom sector, the pion exchange interaction is strong enough to produce states. Thus, from this investigation, it emerges that the hidden-bottom pentaquarks are more likely to form than their hidden-charm counterparts; for this reason, we suggest that the experimentalists should look for states in the bottom sector.

We obtain the Ruppeiner geometry associated with the nonextended state space ($\mathrm{\Lambda }$ constant) of the charged Gauss-Bonnet AdS (GB-AdS) black holes and confirm that the state space Riemannian manifold becomes strongly curved in regions where the black hole system develops strong statistical correlations in the grand canonical ensemble ($M$ and $Q$ fluctuating). We establish the exact proportionality between the state space scalar curvature $R$ and the inverse of the singular free energy near the isolated critical point for the grand canonical ensemble in spacetime dimension $d=5$, thus hopefully moving a step closer to the agenda of a concrete physical interpretation of $R$ for black holes. On the other hand, we show that while $R$ signals the Davies transition points (which exist in GB-AdS black holes for $d\ge 6$) through its divergence, it does not scale as the inverse of the singular free energy there. Furthermore, adapting to the black hole case the ideas developed in [1] in the context of pure fluids, we find that the state space geometry encodes phase coexistence and first order transitions, identifies the asymptotically critical region and even suggests a Widom-line-like crossover regime in the supercritical region for $5-d$ case. The sign of $R$ appears to imply a significant difference between the microscopic structure of the small and the large black hole branches in $d=5$. We show that thermodynamic geometry informs the microscopic nature of coexisting thermal GB-AdS and black hole phases near the Hawking-Page phase transition.

The methods of the renormalization group and the $ϵ$-expansion are applied to quantum gravity revealing the existence of an asymptotically safe fixed point in spacetime dimensions higher than two. To facilitate this, physical renormalization schemes are exploited where the renormalization group flow equations take a form which is independent of the parameterisation of the physical degrees of freedom (i.e. the gauge fixing condition and the choice of field variables). Instead the flow equation depends on the anomalous dimensions of reference observables. In the presence of spacetime boundaries we find that the required balance between the Einstein-Hilbert action and Gibbons-Hawking-York boundary term is preserved by the beta functions. Exploiting the $ϵ$-expansion near two dimensions we consider Einstein gravity coupled to matter. Scheme independence is generically obscured by the loop-expansion due to breaking of two-dimensional Weyl invariance. In schemes which preserve two-dimensional Weyl invariance we avoid the loop expansion and find a unique ultraviolet (UV) fixed point. At this fixed point the anomalous dimensions are large and one must resum all loop orders to obtain the critical exponents. Performing the resummation a set of universal scaling dimensions are found. These scaling dimensions show that only a finite number of matter interactions are relevant. This is a strong indication that quantum gravity is renormalizable.

There is a class of higher derivative gravity theories that are in some sense natural extensions of cosmological Einstein’s gravity with a unique maximally symmetric classical vacuum and only a massless spin-2 excitation about the vacuum and no other perturbative modes. These theories are of the Born-Infeld determinant form. We show that the macroscopic dynamical entropy as defined by Wald for bifurcate Killing horizons in these theories are equivalent to the geometric Bekenstein-Hawking entropy (or more properly Gibbons-Hawking entropy for the case of de Sitter spacetime) but given with an effective gravitational constant which encodes all the information about the background spacetime and the underlying theory. We also show that the higher curvature terms increase the entropy. We carry out the computations in generic $n$ dimensions including the particularly interesting limits of three, four and infinite number of dimensions. We also give a preliminary discussion about the black hole entropy in generic dimensions for the Born-Infeld theories.

In Newtonian fluid dynamics simulations in which composition has been tracked by a nuclear reaction network, energy generation due to composition changes has generally been handled as a separate source term in the energy equation. A relativistic equation in conservative form for total fluid energy, obtained from the spacetime divergence of the stress-energy tensor, in principle encompasses such energy generation; but it is not explicitly manifest. An alternative relativistic energy equation in conservative form—in which the nuclear energy generation appears explicitly, and that reduces directly to the Newtonian $\text{internal}+\text{kinetic energy}$ in the appropriate limit—emerges naturally and self-consistently from the difference of the equation for total fluid energy and the equation for baryon number conservation multiplied by the average baryon mass $m$, when $m$ is expressed in terms of contributions from the nuclear species in the fluid, and allowed to be mutable.

Spinning neutron stars asymmetric with respect to their rotation axis are potential sources of continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a fully coherent search, based on matched filtering, which uses the position and rotational parameters obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signal-to-noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch between the assumed and the true signal parameters. For this reason, narrow-band analysis methods have been developed, allowing a fully coherent search for gravitational waves from known pulsars over a fraction of a hertz and several spin-down values. In this paper we describe a narrow-band search of 11 pulsars using data from Advanced LIGO’s first observing run. Although we have found several initial outliers, further studies show no significant evidence for the presence of a gravitational wave signal. Finally, we have placed upper limits on the signal strain amplitude lower than the spin-down limit for 5 of the 11 targets over the bands searched; in the case of J1813-1749 the spin-down limit has been beaten for the first time. For an additional 3 targets, the median upper limit across the search bands is below the spin-down limit. This is the most sensitive narrow-band search for continuous gravitational waves carried out so far.

We calculate the nucleon axial form factor up to the leading one-loop order in a covariant chiral effective field theory with the $\mathrm{\Delta }(1232)$ resonance as an explicit degree of freedom. We fit the axial form factor to the latest lattice QCD data and pin down the relevant low-energy constants. The lattice QCD data, for various pion masses below 400 MeV, can be well described up to a momentum transfer of $\sim 0.6\mathrm{GeV}$. The $\mathrm{\Delta }(1232)$ loops contribute significantly to this agreement. Furthermore, we extract the axial charge and radius based on the fitted values of the low-energy constants. The results are $g_A=1.237(74)$ and $⟨r_A^2⟩=0.263(38){\mathrm{fm}}^2$. The obtained coupling $g_A$ is consistent with the experimental value if the uncertainty is taken into account. The axial radius is below but in agreement with the recent extraction from neutrino quasielastic scattering data on deuterium, which has large error bars. Up to our current working accuracy, $r_A$ is predicted only at leading order, i.e., the one-loop level. A more precise determination might need terms of $\mathcal{O}(p^5)$.

We provide a general framework for the derivation of the hydrodynamical corrections to the QCD electromagnetic emissivities in a viscous fluid. Assuming that the emission times are short in comparison to the fluid evolution time, we show that the leading corrections in the fluid gradients are controlled by the bulk and shear tensors times pertinent response functions involving the energy-momentum tensor. In a hadronic fluid phase, we detail these contributions using spectral functions. Using the vector dominance approximation, we show that the bulk viscosity correction to the photon rate is sizable, while the shear viscosity is negligible for about all frequencies. In the partonic phase near the transition temperature, we provide an assessment of the viscous corrections to the photon and dilepton emissions, using a nonperturbative quark-gluon plasma with soft thermal gluonic corrections in the form of operators of leading mass dimension. Again, the thermal bulk viscosity corrections are found to be larger than the thermal shear viscosity corrections at all energies for both the photon and dilepton in the partonic phase.

We present a field theoretical model unifying grand unified theory (GUT) and brane world scenario. As a concrete example, we consider $SU(5)$ GUT in $4+1$ dimensions where our $3+1$ dimensional spacetime spontaneously arises on five domain walls. A field-dependent gauge kinetic term is used to localize massless non-Abelian gauge fields on the domain walls and to assure the charge universality of matter fields. We find the domain walls with the symmetry breaking $SU(5)\to SU(3)\times SU(2)\times U(1)$ as a global minimum and all the undesirable moduli are stabilized with the mass scale of $M_{\mathrm{GUT}}$. Profiles of massless standard model particles are determined as a consequence of wall dynamics. The proton decay can be exponentially suppressed.

We consider inflation and supersymmetry breaking in the context of a minimal model of supersymmetry in which the only “low” energy remnant of supersymmetry is the gravitino with a mass of order an EeV. In this theory, the supersymmetry breaking scale is above the inflaton mass, $m\simeq 3\times {10}^{13}\mathrm{GeV}$, as are all sfermion and gaugino masses. In particular, for a no-scale formulation of Starobinsky-like inflation using the volume modulus $T$, we show that inflation can be accommodated even when the supersymmetry breaking scale is very large. Reheating is driven through a gravitational coupling to the two Higgs doublets and is enhanced by the large $\mu$-parameter. This leads to gravitino cold dark matter where the mass is constrained to be in the range $0.1\mathrm{EeV}\lesssim m_{3/2}\lesssim 1000\mathrm{EeV}$.

The clockwork mechanism has recently been proposed as a natural way to generate hierarchies among parameters in quantum field theories. The mechanism is characterized by a very specific pattern of spontaneous and explicit symmetry breaking, and the presence of new light states referred to as “gears.” In this paper we begin by investigating the self-interactions of these gears in a scalar clockwork model and find a paritylike selection rule at all orders in the fields. We then proceed to investigate how the clockwork mechanism can be realized in five-dimensional linear dilaton models from the spontaneous symmetry breaking of a complex bulk scalar field. We also discuss how the clockwork mechanism is manifest in the scalar components of five-dimensional gauge theories in the linear dilaton model, and build their four-dimensional deconstructed analogue. Finally we discuss attempts at building both four-dimensional and five-dimensional realizations of a non-Abelian scalar clockwork mechanism, where in the latter we consider scenarios in which the Goldstone bosons arise from five-dimensional scalar and five-dimensional gauge fields.

Lattice quantum chromodynamics is used to constrain the interactions of two octet baryons at the $SU(3)$ flavor-symmetric point, with quark masses that are heavier than those in nature (equal to that of the physical strange quark mass and corresponding to a pion mass of $\approx 806\mathrm{MeV}$). Specifically, the $S$-wave scattering phase shifts of two-baryon systems at low energies are obtained with the application of Lüscher’s formalism, mapping the energy eigenvalues of two interacting baryons in a finite volume to the two-particle scattering amplitudes below the relevant inelastic thresholds. The leading-order low-energy scattering parameters in the two-nucleon systems that were previously obtained at these quark masses are determined with a refined analysis, and the scattering parameters in two other channels containing the $\mathrm{\Sigma }$ and $\mathrm{\Xi }$ baryons are constrained for the first time. It is found that the values of these parameters are consistent with an approximate $SU(6)$ spin-flavor symmetry in the nuclear and hypernuclear forces that is predicted in the large-$N_c$ limit of QCD. The two distinct $SU(6)$-invariant interactions between two baryons are constrained for the first time at this value of the quark masses, and their values indicate an approximate accidental $SU(16)$ symmetry. The $SU(3)$ irreps containing the $NN({{}^{1}S}_0)$, $NN({{}^{3}S}_1)$ and $\frac{1}{\sqrt{2}}({\mathrm{\Xi }}^{0}n+{\mathrm{\Xi }}^{-}p)({{}^{3}S}_1)$ channels unambiguously exhibit a single bound state, while the irrep containing the ${\mathrm{\Sigma }}^{+}p({{}^{3}S}_1)$ channel exhibits a state that is consistent with either a bound state or a scattering state close to threshold. These results are in agreement with the previous conclusions of the NPLQCD collaboration regarding the existence of two-nucleon bound states at this value of the quark masses.

In a one-boson-exchange model, we study molecular states of double-charm baryon [${\mathrm{\Xi }}_{cc}(3621)$] and a charmed meson ($D$ and $D^{*}$). Our model indicates that there exist two possible triple-charm molecular pentaquarks, a ${\mathrm{\Xi }}_{cc}D$ state with $I(J^P)=0(1/2^{-})$, and a ${\mathrm{\Xi }}_{cc}{D}^{*}$ state with $I(J^P)=0(3/2^{-})$, and we do not find bound solutions for isotriplet states. In addition, we also extend our formula to explore ${\mathrm{\Xi }}_{cc}{\overline{B}}^{(*)}$, ${\mathrm{\Xi }}_{cc}{\overline{D}}^{(*)}$, and ${\mathrm{\Xi }}_{cc}{B}^{(*)}$ systems and find more possible heavy flavor molecular pentaquarks, a ${\mathrm{\Xi }}_{cc}\overline{B}$ state with $I(J^P)=0(1/2^{-})$, a ${\mathrm{\Xi }}_{cc}{\overline{B}}^{*}$ state with $I(J^P)=0(3/2^{-})$, and ${\mathrm{\Xi }}_{cc}{\overline{D}}^{*}/{\mathrm{\Xi }}_{cc}{B}^{*}$ states with $I(J^P)=0(1/2^{-})$. Experimental research for these predicted triple-charm molecular pentaquarks is encouraged.