Dualities provide deep insight into physics by relating two seemingly distinct theories. Here we consider a duality between lattice fermions and bosons in ($2+1$) spacetime dimensions, relating free massive Dirac fermions to Abelian Chern-Simons Higgs (ACSH) bosons. To establish the duality, we represent the exact partition function of the lattice fermions in terms of the writhe of fermionic worldlines. On the bosonic side, the partition function is expressed in the writhe of the vortex loops of the particle-vortex dual of the ACSH Lagrangian. In the continuum and scaling limit, we show these to be identical. This result can be understood from the closed fermionic worldlines being direct mappings of the ACSH vortex loops, with the writhe keeping track of particle statistics.

The entanglement entropy of two-body elastic scattering at high energies is studied by using the model-independent Lévy imaging method for investigating the hadron structure. It is considered the finite entropy in the momentum Hilbert space properly regularized and the results are compared to recent evaluation using the diffraction peak approximation. We present the entropy for RHIC, Tevatron and LHC energies pointing out the underlying uncertainties.

Fermi condensation is usually a phenomena of strongly correlated system. In this paper, we point out a novel mechanism for condensation of Dirac fermions due to the Weyl anomaly. The condensation has its physical origin in the nontrivial response of the fermion vacuum to changes in the background spacetime (either boundary location or the background metric), and can be felt when a background scalar field is turned on. The scalar field can be, for example, the Higgs field in a fundamental theory or the phonon in condensed matter system. For a spacetime with boundaries, the induced Fermi condensate is inversely proportional to the proper distance from the boundary. For a conformally flat spacetime without boundaries, Fermi condensation depends on the conformal factor and its derivatives. We also generalize the Banks-Casher relation which relates the Fermi condensate to the zero mode density of the Dirac operator to a local form. Due to its universal nature, this anomaly induced Fermi condensate can be expected to have a wide range of applications in physics.

Taking a thermodynamic perspective, we study the weak gravity conjecture in the context of four-dimensional Einstein-Maxwell-dilaton theory. We find closed-form expressions for the corrected thermodynamic quantities in the presence of four-derivative terms in the action, and in particular the charge-to-mass ratio and entropy, for several families of solutions of special magnetic-to-electric charge ratio or dilaton coupling constant. Assuming that dyonic black holes themselves are the conjectured charged states, this places constraints on the Wilson coefficients of the theory which we show are satisfied for several generic UV completions.

We describe a correspondence between domain wall solutions of Einstein gravity with a single scalar field and self-interaction potential. The correspondence we call conformal scale factor inversion (CSFI) is a map comprising the inversion of the scale factor in conformal coordinates, and a transformation of the field and its potential which preserves the form of the Einstein equations for static and isotropic domain walls. By construction, CSFI maps the asymptotic anti–de Sitter boundary to the vicinity of a naked singularity in a theory with a special Liouville (exponential) scalar field potential; it is also a map in the parameter space of exponential potentials. The correspondence can be extended to linear fluctuations, being akin to an S-duality, and can be interpreted in terms of “SUSY quantum mechanics” for the fluctuation modes. The holographic implementation of CSFI relates the UV and IR regimes of a pair of holographic renormalization group flows; in particular, it is a symmetry of the GPPZ flow.

In this paper, we study the motion of test particles around two exact charged black hole solutions in Einstein-Æther theory. Specifically, we first consider the quasiperiodic oscillations (QPOs) and their resonances generated by the particle moving in the Einstein-Æther black hole and then turn to study the periodic orbits of the massive particles. For QPOs, we drop the usually adopted assumptions ${\nu }_U={\nu }_{\theta }$, ${\nu }_L={\nu }_r$, and ${\nu }_U/{\nu }_L=3/2$ with ${\nu }_U$ (${\nu }_L$) and ${\nu }_r$ (${\nu }_{\theta }$) being the upper (lower) frequency of QPOs and radial (vertical) epicyclic frequency of the orbiting particles, respectively. Instead, we put-forward a new working ansatz for which the Keplerian radius is much closer to that of the innermost stable circular orbit and explore in detail the effects of the æther field on the frequencies of QPOs. We then realize good curves for the frequencies of QPOs, which fit to data of three microquasars very well by ignoring any effects of rotation and magnetic fields. The innermost stable circular orbits (isco) of timelike particles are also analyzed, and we find the isco radius increases with increasing $c_{13}$ for the first type black hole while decreases with increasing $c_{14}$ for the second one. We also obtain several periodic orbits and find that they share similar taxonomy schemes as the periodic equatorial orbits in the Schwarzschild/Kerr metrics, in addition to exact solutions for certain choices of the Einstein-Æ ther parameters. The equations for null geodesics are also briefly considered, where we study circular photon orbits and bending angles for gravitational lensing.

By extending the framework of the gravitational clock compass we show how a suitably prepared set of clocks can be used to extract information about the gravitational field in the context of general relativity. Conceptual differences between the extended and the standard clock compass are highlighted. Particular attention is paid to the influence of kinematic quantities on the measurement process and the setup of the compass. Additionally, we present results of simulations of the inference process for the acceleration and the curvature components. Several examples of different strategies for the computation of the posterior probability distributions of the curvature components are discussed. This allows us to anticipate the precision with which physical quantities could be determined in a realistic measurement.

Detection and parameter estimation of binary neutron star merger remnants can shed light on the physics of hot matter at supranuclear densities. Here we develop a fast, simple model that can generate gravitational waveforms, and show it can be used for both detection and parameter estimation of postmerger remnants. The model consists of three exponentially damped sinusoids with a linear frequency-drift term. We test the model against nine equal-mass numerical-relativity simulations selected for emission of gravitational waves for $\gtrsim 25\mathrm{ms}$. The median fitting factors between the model waveforms and numerical-relativity simulations exceed 0.90. We detect remnants at a postmerger signal-to-noise ratio of $\ge 7$ using a Bayes-factor detection statistic with a threshold of 3000. We can constrain the primary postmerger frequency to ${\pm }_{1.2}^{1.4}\%$ at postmerger signal-to-noise ratios of 15 with an increase in precision to ${\pm }_{0.2}^{0.3}\%$ for postmerger signal-to-noise ratios of 50. The tidal coupling constant can be constrained to ${\pm }_{12}^9\%$ at postmerger signal-to-noise ratios of 15, and $\pm 5\%$ at postmerger signal-to-noise ratios of 50 using a hierarchical inference model.

We study the response of the electron mass to an externally applied electrical field. As a consequence of nonlinear electromagnetic (EM) effective action, the mass of a particle diminishes in the presence of an externally applied electric field. We consider modification of the muon anomalous magnetic moment $g-2$ due to electron loop insert in higher order. Since the virtual electron pair is in close proximity to the muon, it experiences strong field phenomena. We show that the current theory-experiment muon $g-2$ discrepancy could originate in the (virtual) electron mass nonperturbative modification by the strong muon EM field. The magnitude of the electron mass modification can be also assessed via enhancement of $e^{+}{e}^{-}$-pair production in strong fields.

We present a thorough analysis of the sequential freeze-in mechanism for dark matter production in the early Universe. In this mechanism the dark matter relic density results from pair annihilation of mediator particles which are themselves produced by thermal collisions of standard model particles. Below some critical value of the mediator coupling to standard model fields, this sequential channel dominates over the usual freeze-in where dark matter is directly produced from thermal collisions, even when the mediator is not in thermal equilibrium. The latter case requires computing the full nonthermal distribution of the mediators, for which finite temperature corrections are particularly important.

Despite the popularity of two-Higgs-doublet models (2HDMs) with a gauged Abelian flavor symmetry, the allowed Yukawa textures have only been partly explored so far. In this work, we classify and compare every anomaly-free instance, in the case of having two generations of right-handed neutrinos and a type-I seesaw mechanism. We found 16 valid implementations in total, out of which 11 agree well with current experimental bounds. To our knowledge, neither of these models have been considered previously.

The Froissart bound on the total cross section, ${\sigma }_t$, is subjected to test against very high energy data. We have found no clear evidence for its violation. The scaling property of the differential cross section in the diffraction region is investigated. It exhibits scaling in the ISR, SPS, Tevatron, and LHC energy domain which had hitherto remained unexplored. The slope of the diffraction peak is fitted and the data are tested against the rigorous bounds.

A search for long-lived particles decaying into hadrons and at least one muon is presented. The analysis selects events that pass a muon or missing-transverse-momentum trigger and contain a displaced muon track and a displaced vertex. The analyzed dataset of proton-proton collisions at $\sqrt{s}=13\mathrm{TeV}$ was collected with the ATLAS detector and corresponds to $136{\mathrm{fb}}^{-1}$. The search employs dedicated reconstruction techniques that significantly increase the sensitivity to long-lived particle decays that occur in the ATLAS inner detector. Background estimates for Standard Model processes and instrumental effects are extracted from data. The observed event yields are compatible with those expected from background processes. The results are presented as limits at 95% confidence level on model-independent cross sections for processes beyond the Standard Model, and interpreted as exclusion limits in scenarios with pair production of long-lived top squarks that decay via a small $R$-parity-violating coupling into a quark and a muon. Top squarks with masses up to 1.7 TeV are excluded for a lifetime of 0.1 ns, and masses below 1.3 TeV are excluded for lifetimes between 0.01 ns and 30 ns.

The proposed India-based Neutrino Observatory will host a 50 kton magnetized iron calorimeter (ICAL) with resistive plate chambers as its active detector element. Its primary focus is to study charged-current interactions of atmospheric muon neutrinos via the reconstruction of muons in the detector. We present the first study of the energy and direction reconstruction of the final state lepton and hadrons produced in charged current interactions of atmospheric electron neutrinos at ICAL and the sensitivity of these events to neutrino oscillation parameters ${\theta }_{23}$ and $\mathrm{\Delta }{m}_{32}^2$. However, the signatures of these events are similar to those from neutral-current interactions and charged-current muon neutrino events in which the muon track is not reconstructed. On including the entire set of events that do not produce a muon track, we find that reasonably good sensitivity to ${\theta }_{23}$ is obtained, with a relative $1\sigma$ precision of 15% on the mixing parameter ${\sin }^2{\theta }_{23}$, which decreases to 21%, when systematic uncertainties are considered.

The properties of interior spacetimes sourced by stationary cylindrical anisotropic fluids are here analytically studied for both nonrigid and rigid rotation. As regards nonrigid rotation, this is, to our knowledge, the first work dedicated to such a study. We give here a complete equation set describing these spacetime properties. In particular, we focus our attention on both nonrigid and rigid rotation gravito-electromagnetic features and are thus led to display strong hints in favor of conjecturing purely electric Weyl tensor existence in this framework. We have also been able to characterize new purely magnetic physically consistent spacetimes and have found new rigidly rotating exact solution classes to the five Einstein’s field equations pertaining to the issue and the two purely magnetic constraints we have derived for this purpose. This should be considered as a prominent result, since extremely few purely magnetic exact solutions are available in the literature.

In this paper we investigate the acceleration in relativistic jets of high-energy protons preaccelerated in the magnetosphere of a supermassive black hole. The proton reaches maximum energy when passing the total potential difference of $U$ between the jet axis and its periphery. This voltage is created by a rotating black hole and transmitted along magnetic field lines into the jet. It is shown that the trajectories of proton in the jet are divided into three groups: untrapped, trapped and not accelerated. Untrapped particles are not kept by poloidal and toroidal magnetic fields inside the jet, so they escape out the jet and their energy is equal to the maximum value, $eU$. Trapped protons are moving along the jet with oscillations in the radial direction. Their energy varies around the value of $0.74eU$. In a strong magnetic field protons preaccelerated in the magnetosphere are pressed to the jet axis and practically are not accelerated in the jet. The work defines acceleration regimes for a range of the most well-known AGN objects with relativistic jets and for the microquasar SS433.

We present results for lattice QCD with staggered fermions in the limit of infinite gauge coupling, obtained from a worm-type Monte Carlo algorithm on a discrete spatial lattice but with continuous Euclidean time. This is obtained by sending both the anisotropy parameter $\xi =a_{\sigma }/a_{\tau }$ and the number of time slices $N_{\tau }$ to infinity, keeping the ratio $aT=\xi /N_{\tau }$ fixed. The obvious gain is that no continuum extrapolation $N_{\tau }\to \infty$ has to be carried out. Moreover, the algorithm is faster, and the sign problem disappears. We derive the continuous time partition function and the corresponding Hamiltonian formulation. We compare our computations with those on discrete lattices and study both zero and finite temperature properties of lattice QCD in this regime.

We discuss how the latest data on $X(3872)$ in $B$ and $B_s$ decays speak about its tetraquark nature. The established decay pattern, including the up-to-date observations by CMS, are explained by the mixing of two quasidegenerate, unresolvable neutral states. The same mechanism also explains isospin violations in $X$ decays and strongly suggests that the lurking charged partners are required to have very small branching fractions in $J/\psi {\rho }^{\pm }$, well below the current experimental limits. In addition, a new prediction on the decay into $J/\psi \omega$ final states is attained. The newest experimental observations are found to give thrust to the simplest tetraquark picture and call for a definitive, in-depth study of final states with charged $\rho$ mesons.

The presence of geometric scaling within the $p_T$ spectra of produced hadrons at high energy $pp$ collisions using small-$x$ $k_T$-factorization is investigated. It is proposed a phenomenological parameterization for the unintegrated gluon distribution in the scaling range that reproduces the features of the differential cross section both in the saturated and dilute perturbative QCD regimes. As the saturation scale acts as an effective regulator of the infrared region, the extension of the model to quantities usually associated to soft physics is studied. The approach is applied to compute the average $p_T$ and the rapidity distribution of produced gluons at high energies.