Gravitational waves (GWs) are useful to test gravitational theories and to probe the physics in the early universe. In this paper, we investigate the scalar induced gravitational waves (SIGWs) in symmetric teleparallel gravity with a parity-violating term. The presence of the parity-violating term leads to the velocity birefringence effect of the SIGWs. However, after taking into account the observational constraints on the speed of GWs, the contribution from the parity-violating term to SIGWs is negligible. Nevertheless, the contribution to SIGWs from the perturbations of the connection can be significant, and results in a multipeak structure in the energy density of SIGWs. This feature makes the symmetric teleparallel gravity distinguishable from the general relativity.

Loss of unitarity in an effective field theory is often cured by the appearance of dynamical resonances, revealing the presence of new degrees of freedom. These resonances may manifest themselves when suitable unitarization techniques are implemented in the effective theory, which in the scalar-isoscalar channel require making use of the coupled-channel formalism. Conversely, experimental detection of a resonance may provide interesting information on the couplings and constants of the relevant effective theory. By applying the systematic procedure developed in previous works, we will attempt to accommodate a possible scalar resonance with mass around 650 GeV for which there is preliminary evidence at the LHC in the vector-boson fusion channel. The results are interesting; the resonance can be accommodated within the experimentally allowed range of next-to-leading order coefficients in the Higgs effective field theory but in a rather nontrivial manner. Interestingly, its width and production cross section turn out to agree with the tentative experimental results.

We study lattice cutoff effects on the confinement-deconfinement transition and the $Z_3$ symmetry in $SU(3)$-Higgs theory in $3+1$ dimensions. The Higgs in this study is a complex triplet with vanishing bare mass and quartic coupling. The lattice cutoff is regulated by varying the number of temporal lattice sites, $N_{\tau }$. Our results show that the nature of the confinement-deconfinement transition depends on $N_{\tau }$. For $N_{\tau }=2$ the transition is found to be the end point of a first-order transition and is first order for $N_{\tau }\ge 3$. The distributions of the Polyakov loop and other observables, sensitive to the $Z_3$ symmetry, show that the strength of $Z_3$ explicit breaking decreases with $N_{\tau }$. Up to $T\simeq 2T_c$, the free energy difference between $Z_3$ states decreases with $N_{\tau }$, suggesting the realization of $Z_3$ symmetry in the continuum limit.

We demonstrate that the Higgs boson mass can be extracted from the dispersion relation obeyed by the correlation function of two $b$-quark scalar currents. The solution to the dispersion relation with the input from the perturbative evaluation of the correlation function up to next-to-leading order in QCD and with the $b$-quark mass $m_b=4.43\mathrm{GeV}$ demands a specific Higgs mass 114 GeV. Our observation offers an alternative resolution to the long-standing fine-tuning problem of the Standard Model (SM); the Higgs mass is determined dynamically for the internal consistency of the SM. The similar formalism, as applied to the correlation function of two $b$-quark vector currents with the same $m_b$, leads to the $Z$ boson mass 90.8 GeV. This solution exists only when the $Z$- and $W$-boson masses are proportionate, conforming to the Higgs mechanism of the electroweak symmetry breaking. We then consider the mixing between the $Q\overline{u}$ and $\overline{Q}u$ states for a fictitious heavy quark $Q$ and a $u$ quark through the $b\overline{b}$ channel, inspired by our earlier analysis of neutral meson mixing. Its dispersion relation, given the perturbative input from the responsible box diagrams and the same $m_b$, fixes the top-quark mass 176 GeV. It is highly nontrivial to predict the above electroweak-scale masses with at most 9% deviation from their measured values using the single parameter $m_b$. More accurate results are expected, as more precise perturbative inputs are adopted.

We introduce an enhanced binding energy $B_{QQ}$ between heavy-heavy quarks $QQ$ and a flux-tube correction into the chromomagnetic interaction model to study nonstrange doubly heavy tetraquarks $T_{QQ}$ ($Q=c,b$). A simple relation in terms of baryon masses is proposed to estimate the binding energies $B_{QQ}$ and thereby map the flux-tube corrections in doubly heavy tetraquarks $T_{cc}$, $T_{bb}$, and $T_{bc}$. Our computation via diagonalization of chromomagnetic interaction predicts the doubly charmed tetraquark $T_{cc}$ (in color ${\overline{3}}_c\otimes 3_c$) and $T_{cc}^{*}$ (in $6_c\otimes {\overline{6}}_c$) with $I{J}^P=01^{+}$ to have masses of 3879.2 and 4287.6 MeV, respectively, with the former being in consistent with the measured mass $3874.7\pm 0.05\mathrm{MeV}$ of the doubly charmed tetraquark $T_{cc}(1^{+})=cc\overline{u}\overline{d}$ discovered by LHCb. Further mass predictions are given of the doubly bottom tetraquarks $T_{bb}$ and the bottom-charmed tetraquarks $T_{bc}$ with $J^P=0^{+},1^{+},2^{+}$, and $I=0$, 1. A chromomagnetic mixing between the color configurations ${\overline{3}}_c\otimes 3_c$ and $6_c\otimes {\overline{6}}_c$ is noted for the bottom-charmed states $T_{bc}$ with $I{J}^P=01^{+}$ and $I{J}^P=1(0^{+},1^{+})$.

The study of $J/\psi$ photoproduction at low energies has consequences for the understanding of multiple aspects of nonperturbative QCD, ranging from mechanical properties of the proton to the binding inside nuclei and the existence of hidden-charm pentaquarks. Factorization of the photon-$c\overline{c}$ and nucleon dynamics or vector meson dominance are often invoked to justify these studies. Alternatively, open-charm intermediate states have been proposed as the dominant mechanism underlying $J/\psi$ photoproduction. As the latter violates this factorization, it is important to estimate the relevance of such contributions. We analyze the latest differential and integrated photoproduction cross sections from the GlueX and $J/\psi -007$ experiments. We show that the data can be adequately described by a small number of partial waves, which we parametrize with generic models enforcing low-energy unitarity. The results suggest a non-negligible contribution from open-charm intermediate states. Furthermore, most of the models present an elastic scattering length incompatible with previous extractions based on vector meson dominance and thus call into question its applicability to heavy mesons. Our results indicate a wide array of physics possibilities that are compatible with present data and need to be disentangled.

The strong coupling in the effective quark mass was usually taken as a constant in a quasiparticle model while it is, in fact, running with an energy scale. With a running coupling, however, the thermodynamic inconsistency problem appears in the conventional treatment. We show that the renormalization subtraction point should be taken as a function of the summation of the biquadratic chemical potentials if the quark’s current masses vanish, in order to ensure full thermodynamic consistency. Taking the simplest form, we study the properties of up-down ($ud$) quark matter, and confirm that the revised quasiparticle model fulfills the quantitative criteria for thermodynamic consistency. Moreover, we find that the maximum mass of an $ud$ quark star can be larger than 2 times the solar mass, reaching up to $2.31M_{\odot }$, for reasonable model parameters. However, to further satisfy the upper limit of tidal deformability ${\tilde{\mathrm{\Lambda }}}_{1.4}\le 580$ observed in the event GW170817, the maximum mass of an $ud$ quark star can only be as large as $2.08M_{\odot }$, namely $M_{\max }\lesssim 2.08M_{\odot }$. In other words, our results indicate that the measured tidal deformability for event GW170817 places an upper bound on the maximum mass of $ud$ quark stars, but does not rule out the possibility of the existence of quark stars composed of $ud$ quark matter, with a mass of about 2 times the solar mass.

We derive covariant equations describing the three-quark bound state in terms of quark and diquark degrees of freedom. The equations are exact in the approximation where three-body forces are neglected. A feature of these equations is that they unify two often-used but seemingly unrelated approaches that model baryons as quark-diquark systems; namely, (i) the approach using Poincaré covariant $\mathrm{quark}+\mathrm{diquark}$ Faddeev equations driven by a one-quark-exchange kernel [pioneered by Cahill et al., Aust. J. Phys. 42, 129 (1989) and Reinhardt, Phys. Lett. B 244, 316 (1990)], and (ii) the approach using the quasipotential quark-diquark bound-state equation where the kernel consists of the lowest-order contribution from an underlying quark-quark potential [pioneered by Ebert et al., Z. Phys. C 76, 111 (1997)]. In particular, we show that each of these approaches corresponds to the unified equations with its kernel taken in different, nonoverlapping, approximations.

The spin-$3/2$ to spin-$1/2$ doubly heavy baryon transition magnetic dipole $G_M$ and electric quadrupole $G_E$ form factors are calculated in the framework of the light cone sum rules method. Moreover, the decay widths of corresponding radiative transitions are estimated. Obtained results of magnetic dipole moments $G_M$ and decay widths are compared with the results present in the literature.

We present a study of mass spectra and electromagnetic couplings of $S$- and $P$-wave baryons containing one, two or three heavy quarks, either charm ($c$) or bottom ($b$), in the framework of a nonrelativistic harmonic-oscillator quark model. A simultaneous fit to 41 known masses of heavy baryons (40 singly heavy and 1 doubly heavy) shows a rms deviation of 19 MeV. We present equal-spacing mass rules for excited baryons which may help to assign quantum numbers to experimentally observed heavy baryons. Explicit expressions are derived for electromagnetic couplings, both for spin-flavor matrix elements and radial integrals.

A recent paper [1] within a phenomenological dark matter framework with a massive graviton in the external state argued that a divergence with increasing center-of-momentum energy arising from the longitudinal polarizations of the graviton. In this paper we point out that in processes such as graviton-photon production from matter annihilation, $f\overline{f}\to G\gamma$, no such anomalous divergences occur at tree level. This then applies to other tree-level amplitudes related by crossing symmetry such as $\gamma f\to Gf$, $Gf\to \gamma f$, $\gamma \overline{f}\to G\overline{f}$, $f\to fG\gamma$ and so on. We show this by explicitly computing the relevant tree-level diagrams, where we find that delicate cancellations ensure that all anomalously growing terms are well-regulated. Effectively at tree level this is consistent with the operation of a Ward identity associated with the external photon for such amplitudes. The same tree-level results apply if the photon is replaced by a gluon. These results have important consequences for model construction in areas including dark matter, gravity and high-energy physics.

We study coherent states associated with a generalized uncertainty principle (GUP). We separately analyze the cases of positive and negative deformation parameter $\beta$, showing that the ensuing probability distribution is a Tsallis distribution whose nonextensivity parameter $q$ is monotonically related to $\beta$. Moreover, for $\beta <0$ (corresponding to $q<1$), we reformulate the GUP in terms of a one-parameter class of Tsallis entropy-power-based uncertainty relations, which are again saturated by the GUP coherent states. We argue that this combination of coherent states with Tsallis entropy offers a natural conceptual framework allowing one to study the quasiclassical regime of GUP in terms of nonextensive thermodynamics. We substantiate our claim by discussing the generalization of Verlinde’s entropic force and ensuing implications in the late-inflation epoch. The corresponding dependence of the $\beta$ parameter on cosmological time is derived for the reheating epoch. The obtained $\beta$ is consistent with values predicted by both string-theory models and the naturalness principle. Further salient issues, including the derivation of new $\beta$-dependent expressions for the lowest possible value of the spin and Immirzi parameter in loop quantum gravity and the connection of our proposal with the Magueijo-Smolin doubly special relativity are also discussed. This article provides a more extended and comprehensive treatment of our recent article [Phys. Rev. D 105, L121501 (2022)].

The deflection of light in the gravitational field of the Sun is one of the most fundamental consequences for general relativity as well as one of its classical tests first performed by Eddington a century ago. However, despite its center stage role in modern physics, no experiment has tested it in an ostensibly quantum regime where both matter and light exhibit nonclassical features. This paper shows that the interaction which gives rise to the light-bending also induces photon-matter entanglement as long as gravity and matter are treated at par with quantum mechanics. The quantum light-bending interaction within the framework of perturbative quantum gravity highlights this point by showing that the entangled states can be generated already with coherent states of light and matter exploiting the nonlinear coupling induced by graviton exchange. Furthermore, the quantum light-bending interaction is capable of discerning between the spin-2 and spin-0 gravitons thus also providing a test for alternative theories of gravity at short distances and at the quantum level. We will conclude by estimating the order of magnitude of the entanglement generated by employing the linear entropy. In particular, we find that a half-ring cavity of radius 0.25 m placed around a 10 kg mechanical oscillator operating at 150 Hz, could be used to generate linear entropy of order unity using a petawatt laser source at optical wavelengths. While the proposed scheme is beyond the current experimental realities it nonetheless initiates the discussion about testing the spin of the gravitational interaction at the quantum level.

Here we extend the approach developed in [1] to study the thermodynamics of Taub-NUT-AdS and dyonic Taub-NUT-AdS solutions. Furthermore, we investigate in details the possible phase structures of the dyonic Taub-NUT-AdS solution. We show that the first law, Gibbs-Duhem and Smarr’s relations are all satisfied for both solutions. Our study of phase structures shows some intriguing features, which were not reported before, among which the existence of two distinguished critical points with a region of continuous phase transitions in between, and the possibility of merging them into one point. To analyze these phases we consider both canonical and mixed ensembles. The two distinguished critical points occur for the canonical case as well as the mixed cases with $1/2\le {\varphi }_e<1$. Another interesting case is the mixed ensemble with ${\varphi }_e\ge 1$, where we have one critical point but the continuous phase-transition region in the $P-T$ diagram is close to the origin, in contrast with what happens in Reissner-Nordstrom-AdS solutions and Van der Waals fluids, i.e., the continuous phase transition happens only for low-enough pressures and temperatures.

The extensive catalog of waveforms, with details of binary black hole inspiral and merger, offer an opportunity to understand black hole interactions beyond the large separation regime. We envision a research program that focuses on the transfer of angular momentum from spin of the individual holes to the orbital angular momentum and the role of tidal coupling in the process. That analysis will require the formulation of an expression for the orbital angular momentum of a binary, an expression that is useful at small separations, since that regime is well out of the range of Newtonian approximations and is where tidal coupling should be most interesting. We report here such an expression, a binary orbital angular momentum based on numerical relativity results for quasicircular orbits, that agrees remarkably well with a similar quantity constructed with particle-perturbation techniques for the Kerr geometry.

Recently, the cosmological tensions, $H_0$ and $S_8$ in particular, have inspired modification of both pre- and postrecombination physics simultaneously. Early dark energy is a promising pre-recombination solution of the $H_0$ tension, known to be compatible with the cosmic microwave background (CMB). However, the compatibility of early dark energy, as well as general early resolutions, with the CMB is no longer obvious if the late Universe is also modified. Aside from cosmological parameters, the main channel through which late Universe physics affects CMB observables is gravitational lensing. We employed a new method of sampling functions using the Gaussian Process in the Monte Carlo Markov Chain analysis to constrain the shape of the CMB lensing potential. We obtained the early Universe (CMB) only constraints on the full shape of the CMB lensing potential, with the late-time Universe being marginalized over. It is found that CMB data prefers a lensing potential shape that is $\mathrm{\Lambda }\mathrm{CDM}$-like at $80\lesssim L\lesssim 400$ but with enhanced amplitude beyond this range. The obtained shape constraints can serve as a CMB-compatibility guideline for both late and early Universe model building that modifies the lensing potential.

If, after primordial inflation, the Universe undergoes a relatively long reheating period, it could present a phase of matter domination supported by the oscillating inflaton field. During this epoch, small perturbations from the inflaton that reenter the cosmological horizon could virialize to form inflaton structures. If the primordial overdensities are large enough, their associated inflaton structures could collapse to form primordial black holes (PBHs) [L. E. Padilla et al., New mechanism for primordial black hole formation during reheating, Phys. Rev. D 106, 023519 (2022); hereinafter P1.]. For this to happen at a considerable rate, the primordial power spectrum should be enhanced at small scales, a feature typically induced in single-field inflation through an ultraslow roll phase (produced by a nearly inflection point in the inflationary potential). In this paper we consider two specific inflationary potentials that present this nearly inflection point, and we look at the PBH formation rate through the mechanism proposed in P1. We report on constraints to these two specific models from the bounds to PBH abundances. This serves as an illustration of the usefulness of the PBH formation mechanism proposed in P1.

We investigate a scenario where primordial black holes (PBHs) can be the progenitors of supermassive black holes (SMBHs) observed at $z\sim 6$. To this end, we carried out clustering analysis using a sample of 81 quasars at $5.88<z<6.49$, which is constructed in the Subaru High-$z$ Exploration of Low-Luminosity Quasars project, and 11 quasars in the same redshift range selected from the literature. The resulting angular autocorrelation function (ACF) can be fitted to a power law form of ${\omega }_{\theta }=0.045_{-0.106}^{+0.114}{\theta }^{-0.8}$ over a scale of 0.2–10 degrees. We compare the ACF of the quasars to that predicted for the PBH model at $z\sim 6$ and found that such a scenario is excluded for a broad range of parameter space, from which we can conclude that a scenario with PBHs as SMBHs is not viable. We also discuss a model in which SMBHs at $z\sim 6$ originate from the direct collapse of PBH clumps and argue that the observed ACF excludes such a scenario in the context of our PBH model.