We apply the relative weights method to SU(3) gauge theory with staggered fermions of mass 695 MeV at a set of temperatures in the range $151\le T\le 267\mathrm{MeV}$, to obtain an effective Polyakov line action at each temperature. We then apply a mean field method to search for phase transitions in the effective theory at finite densities. The result is a transition line in the plane of temperature and chemical potential, with an end point at high temperature, as expected, but also a second end point at a lower temperature. We cannot rule out the possibilities that a transition line reappears at temperatures lower than the range investigated, or that the second end point is absent for light quarks.

We study the implications of the spontaneous and explicit Z(3) center symmetry breaking for the Polyakov loop susceptibilities. To this end, ratios of the susceptibilities of the real and imaginary parts, as well as of the modulus of the Polyakov loop are computed within an effective model using a color group integration scheme. We show that the essential features of the lattice QCD results of these ratios can be successfully captured by the effective approach. Furthermore we discuss a novel scaling relation in one of these ratios involving the explicit breaking field, volume, and temperature.

Based on the general form of the Bethe-Salpeter wave functions for the bound states consisting of two vector fields, we obtain the general formulas for the decay widths of molecular states composed of two heavy vector mesons with arbitrary spin and parity into a heavy meson plus a light meson. In this approach, our attention is still focused on the internal structure of heavy vector mesons in the molecular state. According to the molecule state model of exotic meson, we give the generalized Bethe-Salpeter wave function of molecular state as a four-quark state. Then the observed $Y(3940)$ state is considered as a molecular state consisting of two heavy vector mesons $D^{*0}{\overline{D}}^{*0}$ and the strong $Y(3940)\to J/\psi \omega$ decay width is calculated. The numerical result is consistent with the experimental values.

We consider static neutron stars within the framework of $R^2$ gravity. The neutron fluid is described by three different types of realistic equations of state (soft, moderately stiff, and stiff). Using the observational data on the neutron star mass-radius relation, it is demonstrated that the characteristics of the objects supported by the isotropic fluid agree with the observations only if one uses the soft equation of state. We show that the inclusion of the fluid anisotropy enables one also to employ more stiff equations of state to model configurations that will satisfy the observational constraints sufficiently. Also, using the standard thin accretion disk model, we demonstrate potentially observable differences, which allow us to distinguish the neutron stars constructed within the modified gravity framework from those described in Einstein’s general relativity.

Efficient multidimensional template placement is crucial in computationally intensive matched-filtering searches for gravitational waves (GWs). Here, we implement the neighboring cell algorithm (NCA) to improve the detection volume of an existing compact binary coalescence (CBC) template bank. This algorithm has already been successfully applied for a binary millisecond pulsar search in data from the Fermi satellite. It repositions templates from overdense regions to underdense regions and reduces the number of templates that would have been required by a stochastic method to achieve the same detection volume. Our method is readily generalizable to other CBC parameter spaces. Here we apply this method to the aligned-single-spin neutron star–black hole binary coalescence inspiral-merger-ringdown gravitational wave parameter space. We show that the template nudging algorithm can attain the equivalent effectualness of the stochastic method with 12% fewer templates.

In this work we have investigated various properties of a spinning gyroscope in the context of Horndeski theories. In particular, we have focused on two specific situations—(a) when the gyroscope follows a geodesic trajectory and (b) when it is endowed with an acceleration. In both these cases, besides developing the basic formalism, we have also applied the same to understand the motion of a spinning gyroscope in various static and spherically symmetric spacetimes pertaining to Horndeski theories. Starting with the Schwarzschild de Sitter spacetime as a warm up exercise, we have presented our results for two charged Galileon black holes as well as for a black hole in scalar coupled Einstein-Gauss-Bonnet gravity. In all these cases we have shown that the spinning gyroscope can be used to distinguish black holes from naked singularities. Moreover, using the numerical estimation of the geodetic precession from the Gravity Probe B experiment, we have constrained the gauge/scalar charge of the black holes in these Horndeski theories. Implications are also discussed.

In the present article, we investigate the Periastron precession for a spinning test particle moving in nearly circular orbits around naked singularities. We consider two well-known solutions that can produce a spacetime with naked singularity—(a) first, the Reissner-Nordström metric, which is a static charged solution with spherical symmetry, and (b) second, the stationary, axisymmetric Kerr metric. For simplicity, we only consider the motion confined on the equatorial plane in both these cases and solve exactly the Mathisson-Papapetrou equations. In addition, we analytically compute the Periastron precession within the framework of linear spin approximation. The inclusion of the spin parameter modifies the results with nonspinning particles and also reflects some interesting properties of the naked geometries. Furthermore, we carried out a numerical approach without any assumptions to probe the large order spin values. The implication of the spin-curvature coupling in connection with the naked geometries is also discussed.

In this paper we investigate the exterior vacuum electromagnetic fields of slow-rotating magnetized compact stars in conformal gravity. Assuming the dipolar magnetic field configuration, we obtain an analytical solution of the Maxwell equations for the magnetic and the electric fields outside a slowly rotating magnetized star in conformal gravity. Furthermore, we study the dipolar electromagnetic radiation and energy losses from a rotating magnetized star in conformal gravity. In order to get constraints on the $L$ parameter of conformal gravity, the theoretical results for the magnetic field of a magnetized star in conformal gravity are combined with the precise observational data of radio pulsar period slowdown, and it is found that the maximum value of the parameter of conformal gravity is less than $L\lesssim 9.5\times {10}^5\mathrm{cm}$ ($L/M\lesssim 5$).

Cosmic strings are generic cosmological predictions of many extensions of the standard model of particle physics, such as a $U(1{)}^{\prime }$ symmetry-breaking phase transition in the early Universe or remnants of superstring theory. Unlike other topological defects, cosmic strings can reach a scaling regime that maintains a small fixed fraction of the total energy density of the Universe from a very early epoch until today. If present, they will oscillate and generate gravitational waves with a frequency spectrum that imprints the dominant sources of total cosmic energy density throughout the history of the Universe. We demonstrate that current and future gravitational wave detectors, such as LIGO and LISA, could be capable of measuring the frequency spectrum of gravitational waves from cosmic strings and discerning the energy composition of the Universe at times well before primordial nucleosynthesis and the cosmic microwave background where standard cosmology has yet to be tested. This work establishes a benchmark case that gravitational waves may provide an unprecedented, powerful tool for probing the evolutionary history of the very early Universe.

We perform a comprehensive analysis of the most common early- and late-universe solutions to the $H_0$, $\mathrm{Ly}\text{−}\alpha$, and $S_8$ discrepancies. When considered on their own, massive neutrinos provide a natural solution to the $S_8$ discrepancy at the expense of increasing the $H_0$ tension. If all extensions are considered simultaneously, the best-fit solution has a neutrino mass sum of $\sim 0.4\mathrm{eV}$, a dark energy equation of state close to that of a cosmological constant, and no additional relativistic degrees of freedom (d.o.f). However, the $H_0$ tension, while weakened, remains unresolved. Motivated by this result, we perform a nonparametric reconstruction of the evolution of the dark energy fluid density (allowing for negative energy densities), together with massive neutrinos. When all data sets are included, there exists a residual $\sim 1.9\sigma$ tension with $H_0$. If this residual tension remains in the future, it will indicate that it is not possible to solve the $H_0$ tension solely with a modification of the late-universe dynamics within standard general relativity. However, we do find that it is possible to resolve the tension if either galaxy baryon acoustic oscillation (BAO) or joint light-curve analysis supernovae data are omitted. We find that negative dark energy densities are favored near redshift $z\sim 2.35$ when including the $\mathrm{Ly}\text{−}\alpha$ BAO measurement (at $\sim 2\sigma$). This behavior may point to a negative curvature, but it is most likely indicative of systematics or at least an underestimated covariance matrix. Quite remarkably, we find that in the extended cosmologies considered in this work, the neutrino mass sum is always close to 0.4 eV regardless of the choice of external data sets, as long as the $H_0$ tension is solved or significantly decreased.

In the present work, we study a warm inflationary model defined by a quasi-exponential inflaton potential and an inflaton decay rate proportional to the Hubble rate. The model is characterized by three free parameters. We compute the power spectrum, the scalar spectral index, as well as the tensor-to-scalar ratio within the framework of the model, and we compare with the latest Planck data and also the BICEP2/Keck-Array data. On the $r-n_s$ plane, we show both the theoretical curves and the contour plots allowed by observations, and we constrain the parameters of the model accordingly. The nonlinear parameter $f_{NL}$, corresponding to primordial non-Gaussianities, is also discussed and we found that the value predicted by our model is within the bounds imposed by current observational data.

We search for the fiveplet singly charged Higgs $H_5^{\pm }$ in the Georgi-Machacek model at the ep colliders. The charged Higgs bosons are produced via the $Z{W}^{\pm }$ fusion process $p{e}^{-}\to j{e}^{-}{H}_5^{\pm }$ and decay as $H_5^{\pm }\to Z{W}^{\pm }\to (l^{+}{l}^{-})(jj)$. With a detector-level simulation at the FCC-eh and LHeC, a multivariate analysis is performed to yield limits on the production cross section times branching ratio $\sigma (p{e}^{-}\to j{e}^{-}{H}_5^{\pm })\times \mathrm{BR}(H_5^{\pm }\to Z{W}^{\pm })$ and on the model parameter $\sin {\theta }_H$ for charged Higgs masses between 200 and 1000 GeV. Considering 10% systematic uncertainty on the background, at the FCC-eh (LHeC) with $1{\mathrm{ab}}^{-1}$ integrated luminosity, for a $H_5^{\pm }$ mass of 600 (200) GeV, the cross section corresponding to the $2\text{−}\sigma$ significance is 0.59 (3.69) fb, corresponding to a $2\text{−}\sigma$ limit on the $\sin {\theta }_H$ is 0.15 (0.41). The effects of $-80\%$ and $+80\%$ electron beam polarizations are also investigated and found to be small for this study.

In this work, we consider expressions for the masses and decay constants of the pseudoscalar mesons in $SU(3)$ chiral perturbation theory. These involve sunset diagrams and their derivatives evaluated at $p^2=m_P^2$ ($P=\pi$, $K$, $\eta$). Recalling that there are three mass scales in this theory, $m_{\pi }$, $m_K$ and $m_{\eta }$, there are instances when the finite part of the sunset diagrams do not admit an expression in terms of elementary functions, and have therefore been evaluated numerically in the past. In a recent publication, an expansion in the external momentum was performed to obtain approximate analytic expressions for $m_{\pi }$ and $F_{\pi }$, the pion mass and decay constant. We provide fully analytic exact expressions for $m_K$ and $m_{\eta }$, the kaon and eta masses, and $F_K$ and $F_{\eta }$, the kaon and eta decay constants. These expressions, calculated using Mellin-Barnes methods, are in the form of double series in terms of two mass ratios. A numerical analysis of the results to evaluate the relative size of contributions coming from loops, chiral logarithms as well as phenomenological low-energy constants is presented. We also present a set of approximate analytic expressions for $m_K$, $F_K$, $m_{\eta }$ and $F_{\eta }$ that facilitate comparisons with lattice results. Finally, we show how exact analytic expressions for $m_{\pi }$ and $F_{\pi }$ may be obtained, the latter having been used in conjunction with the results for $F_K$ to produce a recently published analytic representation of $F_K/F_{\pi }$.

We study the chiral effective theory in the presence of quantum chromodynamics (QCD) vortices. Gauge invariance requires novel terms from vortex singularities in the gauged Wess-Zumino-Witten action, which incorporate anomaly-induced currents along the vortices. We examine these terms for systems with QCD axial domain-walls bounded by vortices (vortons) under magnetic fields. We discuss how the baryon and electric charge conservations are satisfied in these systems through interplay between domain-walls and vortices, manifesting Callan-Harvey’s mechanism of anomaly inflow.

We derive the $k_T$ resummation for doubly heavy-flavored $B_c$ meson decays by including the charm quark mass effect into the known formula for a heavy-light system. The resultant Sudakov factor is employed in the perutrbative QCD study of the “golden channel” $B_c^{+}\to J/\psi {\pi }^{+}$. With a reasonable model for the $B_c$ meson distribution amplitude, which maintains approximate on-shell conditions of both the partonic bottom and charm quarks, it is observed that the imaginary piece of the $B_c\to J/\psi$ transition form factor appears to be power suppressed, and the $B_c^{+}\to J/\psi {\pi }^{+}$ branching ratio is not lower than ${10}^{-3}$. The above improved perturbative QCD formalism is applicable to $B_c$ meson decays to other charmonia and charmed mesons.

A search for the supersymmetric partners of quarks and gluons (squarks and gluinos) in final states containing hadronic jets and missing transverse momentum, but no electrons or muons, is presented. The data used in this search were recorded in 2015 and 2016 by the ATLAS experiment in $\sqrt{s}=13\mathrm{TeV}$ proton-proton collisions at the Large Hadron Collider, corresponding to an integrated luminosity of $36.1{\mathrm{fb}}^{-1}$. The results are interpreted in the context of various models where squarks and gluinos are pair produced and the neutralino is the lightest supersymmetric particle. An exclusion limit at the 95% confidence level on the mass of the gluino is set at 2.03 TeV for a simplified model incorporating only a gluino and the lightest neutralino, assuming the lightest neutralino is massless. For a simplified model involving the strong production of mass-degenerate first- and second-generation squarks, squark masses below 1.55 TeV are excluded if the lightest neutralino is massless. These limits substantially extend the region of supersymmetric parameter space previously excluded by searches with the ATLAS detector.

We study the deconfinement phase transition in ($2+1$)-dimensional holographic $SU(N)$ gauge theories in the presence of an external magnetic field from the holographic hard and soft wall models. We obtain exact solutions for the critical temperature of the deconfinement transition for any range of magnetic field. As a consequence, we find a critical magnetic field $(B_c)$, in which the critical temperature $(T_c)$ vanishes; for $B<B_c$ we have an inverse magnetic catalysis and for $B>B_c$ we have a magnetic catalysis.

We study under what circumstances a separable bipartite system A-B can or cannot become entangled through local interactions with a bilocal entangled source ${\mathrm{S}}_1\text{−}{\mathrm{S}}_2$. We obtain constraints on the general forms of the interaction Hamiltonians coupling A with ${\mathrm{S}}_1$ and B with ${\mathrm{S}}_2$ necessary for A and B to become entangled. We are able to generalize and provide nonperturbative insight on several previous no-go theorems of entanglement harvesting from quantum fields using these general results. We also discuss the role of communication in the process of entanglement extraction, establishing a distinction between genuine entanglement extraction and communication-assisted entanglement generation.

Quasinormal modes of a two-parameter family of Lorentzian wormhole spacetimes, which arise as solutions in a specific scalar-tensor theory associated with braneworld gravity, are obtained using standard numerical methods. Being solutions in a scalar-tensor theory, these wormholes can exist with matter satisfying the weak energy condition. If one posits that the end-state of stellar-mass binary black hole mergers, of the type observed in GW150914, can be these wormholes, then we show how their properties can be measured from their distinct signatures in the gravitational waves emitted by them as they settle down in the postmerger phase from an initially perturbed state. We propose that their scalar quasinormal modes correspond to the so-called breathing modes, which normally arise in gravitational wave solutions in scalar-tensor theories. We show how the frequency and damping time of these modes depend on the wormhole parameters, including its mass. We derive the mode solutions and use them to determine how one can measure those parameters when these wormholes are the endstate of binary black hole mergers. Specifically, we find that if a breathing mode is observed in LIGO-like detectors with design sensitivity, and has a maximum amplitude equal to that of the tensor mode that was observed of GW150914, then for a range of values of the wormhole parameters, we will be able to discern it from a black hole. If in future observations we are able to confirm the existence of such wormholes, we would, at one go, have some indirect evidence of a modified theory of gravity as well as extra spatial dimensions.

We carry on a systematic study of the physical properties of axially symmetric fluid distributions, which appear to be geodesic, shearfree, irrotational, nondissipative, and purely electric, for the comoving congruence of observers, from the point of view of the tilted congruence. The vanishing of the magnetic part of the Weyl tensor for the comoving congruence of observers, suggests that no gravitational radiation is produced during the evolution of the system. Instead, the magnetic part of the Weyl tensor as measured by tilted observers is nonvanishing (as well as the shear, the four–acceleration, the vorticity and the dissipation), giving rise to a flux of gravitational radiation that can be characterized through the super–Poynting vector. This result strengthens further the relevance of the role of observers in the description of a physical system. An explanation of this dual interpretation in terms of the information theory, is provided.