We present a unique Yukawa structure of the Zee model that can accommodate neutrino oscillation data, solves the muon $g-2$ problem, and explains the recent $W$-boson mass measurement. Our Yukawa structure is minimal in the sense that it contains the least possible number of parameters. In this minimal scenario, neutrino masses are quasidegenerate and are compatible with both normal and inverted orderings. The mixing angle ${\theta }_{23}$ is predicted to lie in the second (first) octant for normal (inverted) ordering. In both cases, the $CP$ violating phase is close to $3\pi /2$. The minimal texture also predicts a large branching fraction of the heavy neutral Higgs boson into a pair of electron and muon.

We calculate chromoelectric and chromomagnetic correlators in quenched QCD at $1.5T_c$ and ${10}^4{T}_c$, with the aim to estimate the heavy quark diffusion coefficient at leading order in the inverse heavy quark mass expansion, ${\kappa }_{\mathrm{E}}$, as well as the coefficient of the first mass-suppressed correction, ${\kappa }_{\mathrm{B}}$. We use gradient flow for noise reduction. At $1.5T_c$ we obtain $1.70\le {\kappa }_{\mathrm{E}}/T^3\le 3.12$ and $1.03<{\kappa }_{\mathrm{B}}/T^3<2.61$. The latter implies that the mass-suppressed effects in the heavy quark diffusion coefficient are 20% for bottom quarks and 34% for charm quarks at this temperature.

We study the pattern of chiral symmetry breaking in the $\psi \chi \eta$ model [with the chiral fermion sector containing ${\psi }^{\{ij\}}$, ${\chi }_{[ij]}$, and ${\eta }_i^A$; see Armoni and Shifman Phys. Rev. D 85, 105003 (2012)] on ${\mathbb{R}}^3\times S_L^1$ and derive implications forcing ${\mathbb{R}}^4$ physics. Center-symmetric vacua are stabilized by a double-trace deformation. With the center symmetry maintained at small $L(S^1)\ll {\mathrm{\Lambda }}^{-1}$, i.e., at weak coupling, no phase transitions are expected in passing to large $L(S^1)\gg {\mathrm{\Lambda }}^{-1}$ (here, $\mathrm{\Lambda }$ is the dynamical Yang-Mills scale). Starting with the small-$L$ limit, we find the leading-order nonperturbative corrections in the given theory. The instanton-monopole operators induce the adjoint chiral condensate $⟨{\psi }^{\{ij\}}{\chi }_{[jk]}⟩\ne 0$ at weak coupling, i.e., at $L(S^1)\ll {\mathrm{\Lambda }}^{-1}$. Then adiabatic continuity tells us that $⟨{\psi }^{\{ij\}}{\chi }_{[jk]}⟩\ne 0$ exists on ${\mathbb{R}}^4$, in full accord with the prediction from Bolognesi et al. [Phys. Rev. D 97, 094007 (2018)]. Simultaneously with $⟨{\psi }^{\{ij\}}{\chi }_{[jk]}⟩\sim {\mathrm{\Lambda }}^3{\delta }_k^i$, the $\mathrm{SU}(N_c)$ gauge symmetry is spontaneously broken at strong coupling down to its maximal Abelian subgroup.

We study the synchrotron radiation emitted by a charged fermion, rotating as a part of a larger system, in a constant magnetic field $B$ parallel to the axis of rotation. The rotation is classical and independent of the magnetic field. The angular velocity of rotation $\mathrm{\Omega }$ is assumed to be much smaller than the inverse magnetic length $\sqrt{qB}$, which allows us to ignore the boundary effects at $r=1/\mathrm{\Omega }$. We refer to such rotation as slow, even though in absolute value it may be an extremely rapid rotation. Using the exact solution of the Dirac equation, we derived the intensity of electromagnetic radiation, its spectrum, and its chirality. We demonstrate by explicit numerical calculation that the effect of rotation on the radiation intensity increases with the particle energy. Depending on the relative orientation of the vectors $\mathbf{\Omega }$ and $\mathit{B}$ and the sign of the electric charge, the rotation can either strongly enhance or strongly suppress the radiation.

We study the near horizon 2D gravity theory which captures the near extremal thermodynamics of Banados-Teitelboim-Zanelli (BTZ) with excess mass $\delta M$ and excess angular momentum $\delta J=\mathcal{L}\delta M$ over extremality. We find that the Jackiw-Teitelboim theory is able to capture such departures from extremality with an additional parameter $\mathcal{L}$ relating it to the near extremal BTZ configuration. We are able to show this by obtaining new simultaneous near horizon near extremal limits of the BTZ geometry parametrized by $\mathcal{L}$. The resulting Jackiw-Teitelboim theory captures the near extremal thermodynamics of such BTZ geometries provided we identify the temperature $T_H^{(2)}$ of the ${\mathit{AdS}}_2$ geometry in the Jackiw-Teitelboim theory to be $T_H^{(2)}=T_H/(1-\mu \mathcal{L})$, where $T_H$ is the BTZ temperature and $\mu$ its chemical potential with $\mu \mathcal{L}<1$.

We study a rich set of four-dimensional superconformal field theories with both central charges identical: $a=c$. These are constructed via the diagonal $\mathcal{N}=2$ or $\mathcal{N}=1$ gauging of the flavor symmetry $G$ of a collection of $\mathcal{N}=2$ Argyres-Douglas theories of type ${\mathcal{D}}_p(G)$, with or without adjoint chiral multiplets, in 2106.12579 and 2111.12092. We compute superconformal indices of some theories where the rank of $G$ is low, performing a refined test for unitarity, and further determine the relevant and marginal operator content in detail. We find that most of these theories flow to interacting superconformal field theories with $a=c$ in the infrared.

In this paper the possible geodesic completeness of an electromagnetic dipole wormhole is studied in detail. The space-time contains a curvature singularity and belongs to a class of solutions to the Einstein-Maxwell equations with a coupled scalar field. Specifically, a numerical analysis is performed to examine congruences of null geodesics that are directed toward the singularity. The results found here show that, depending on the strength of the coupling between the scalar and electromagnetic fields, the wormhole can be either geodesically incomplete or complete. We then focus on those wormholes that are geodesically complete and study the geometry of the neighborhood of their singularity using Kaluza-Klein theory in a five-dimensional space-time. This process allows us to provide a possible explanation of the completeness of geodesics despite unbounded curvature.

We study electromagnetic radiation reaction in curved space and the dynamics of radiating charged particles. The equation of motion for such particles is the DeWitt-Brehme equation, and it contains a particularly complicated, nonlocal, tail term. It has been claimed that the tail term can be neglected in certain magnetized black hole spacetimes, and that radiation reaction may then lead to energy extraction (“orbital widening”) in the absence of an ergoregion. We show that such claims are incorrect, at least in the Newtonian limit: the tail term can never be neglected consistently in the relevant scenarios, and when it is included the reported energy extraction no longer occurs. Thus, previous results are called into question by our work.

It has been suggested that the spectrum of quasinormal modes of rotating black holes is unstable against additional potential terms in the perturbation equation, as the operator associated with the equation is non-self-adjoint. We point out that a bilinear form has been constructed previously to allow a perturbation analysis of the spectrum, which was applied to study the quasinormal modes of weakly charged Kerr-Newman black holes [Phys. Rev. D 91, 044025 (2015)]. The proposed spectral instability should be restated as instability against potential terms that have an infinitesimal “energy” norm that is specifically defined by the type of inner products introduced by Jaramillo et al. and preserving the physical meaning of energy. We argue that it is necessary to address the stability of all previous mode analysis results to reveal their susceptibility to energetically infinitesimal perturbations. In particular, for near-extremal Kerr spacetime, we show that the spectrum of zero-damping modes, which have slow decay rates, is unstable (with order unity fractional change in decay rates) with fine-tuned modification of the potential. The decay rates are, however, always positive with energetically infinitesimal perturbations. If finite potential modifications are allowed near the black hole, it is possible to find superradiantly unstable modes, i.e., a “black hole bomb” without an explicit outer shell. For the zero-damping modes in near-extremal Reissner-Nordström–de Sitter black holes, which are relevant for the breakdown of strong cosmic censorship, we find that the corresponding spectrum is stable under energetically infinitesimal perturbations.

Gravitational decoupling can add hair to the black holes by adding extra sources. The quasinormal modes of a hairy black hole caused by gravitational decoupling for the massless scalar field, electromagnetic field, and gravitational perturbation are investigated. The equations of the effective potential for three perturbations are derived in a hairy black hole spacetime. We also study the time evolution corresponding to the three perturbations, and the quasinormal mode frequencies are calculated using the Prony method through the time-domain profiles. By analyzing the influence of the hairs ($\alpha$, $l_0$ and $Q$) for the black holes we are studying on quasinormal modes, we find that the hairs $\alpha$ and $l_0$ decrease the oscillation frequency of the gravitational-wave signal, and the hair $Q$ increases its oscillation frequency. Furthermore, we calculate the bounds of the greybody factor and high-energy absorption cross section with the sinc approximation, which reveals that the presence of charges ($\alpha$ and $l_0$) generating primary hair can increase the probability of gravitational radiation arriving at spatial infinity, whereas the charge $Q$ from the extra sources does the opposite.

Trying to connect a fundamentally noncommutative spacetime with the conservative perturbative approach to quantum gravity, we are led to the natural question: are noncommutative geometrical effects already present in the regime where perturbative quantum gravity provides a predictive framework? Moreover, is it necessary to introduce noncommutativity by hand, or does it arise through quantum-gravitational effects? We show that the first question can be answered in the affirmative, and the second one in the negative: perturbative quantum gravity predicts noncommutativity at the Planck scale, once one clarifies the structure of observables in the quantum theory.

We investigate the shadow of an exact black hole solution of Einstein’s equations recently proposed by Cardoso et al., to describe a supermassive black hole immersed in a dark matter halo. We analyze and discuss the light rings and the gravitational lensing of this spacetime comparing them with an isolated Schwarzschild black hole. Using backward ray-tracing techniques, we study the shadows cast by such black hole when illuminated by a celestial sphere that emits radiation isotropically. We find that when the dark matter distribution concentrates near the event horizon of the black hole, multiple light rings emerge. In this high compactness regime, the shadows and gravitational lensing are significantly different from the Schwarzschild one. We also use the M87* and SgrA* shadow data, obtained by the Event Horizon Telescope collaboration, to constrain the parameters of the dark matter halo.

The fundamental quasinormal modes of black holes in higher-derivative gravity given by the Einstein-Weyl action are known to be moderately corrected by the Weyl term. Here we will show that the first several overtones are highly sensitive to even a relatively small Weyl correction, which might be important when representing the earlier stage of the black hole ringdown. In addition, we have solved the problem related to the analytical parametrized approximation of the numerical black hole solution in the Einstein-Weyl theory: In some range of parameters, the approximation for the metric developed up to the third order leads to the unusual highly nonmonotonic behavior of the frequencies. We have shown that this problem can be solved via the extension of the parametrization of the metric to higher orders until reaching the regime when the frequencies do not change with further increasing of the order.

The photons emitted by primordial black holes (PBHs) can be a heating factor for interstellar dust. Assuming that dust in the Galaxy has a homogeneous distribution and that PBHs have the same distribution as dark matter (DM), we constrain the fraction of PBHs in DM from the observational dust temperature in the Galaxy.

It is known that primordial black holes (PBHs) can leave an imprint on cosmic microwave background (CMB) anisotropy power spectra, due to their accretion-powered injection of energy into the recombining plasma. Here we study a qualitatively new CMB observable sourced by accreting PBHs: the temperature trispectrum or connected four-point function. This non-Gaussian signature is due to the strong spatial modulation of the PBH accretion luminosity, thus ionization perturbations, by large-scale supersonic relative velocities between PBHs and the accreted baryons. We first derive a factorizable quadratic transfer function for free-electron fraction inhomogeneities induced by accreting PBHs. We then compute the perturbation to the CMB temperature anisotropy due to a general modification of recombination and apply our results to accreting PBHs. We calculate a new contribution to the temperature power spectrum due to the spatial fluctuations of the ionization perturbation induced by accreting PBHs, going beyond past studies that only accounted for its homogeneous part. While these contributions are formally comparable, we find the new part to be subdominant due to the poor correlation of the perturbed temperature field with the standard CMB anisotropy. For the first time, we compute the temperature trispectrum due to accreting PBHs. This trispectrum is weakly correlated with the local-type primordial non-Gaussianity trispectrum; hence constraints on the latter do not lead to competitive bounds on accreting PBHs. We also forecast Planck’s sensitivity to the temperature trispectrum sourced by accreting PBHs. Excitingly, we find it to be more sensitive to PBHs under $\sim {10}^3{M}_{\odot }$ than current temperature-only power-spectrum constraints. This result motivates our future work extending this study to temperature and polarization trispectra induced by inhomogeneously accreting PBHs.

The mass of the axionlike particles could be constrained by the observed black hole spin distribution. In this work, we study such constraints using the LIGO/Virgo data and the recently improved superradiance formula, which agrees better with the numerical results. The effect of the merger timescale ${\tau }_M$ is also carefully investigated with Bayesian analysis. We find the strength of evidence for the range $-12.89\le {\log }_{10}(\mu /\mathrm{eV})-12.57$, which is excluded in the analysis with ${\tau }_{\mathrm{M}}$ fixed at ${10}^7\mathrm{yr}$, could not be simply ruled out. We also find two mass ranges close to ${\log }_{10}(\mu /\mathrm{eV})=-12.10$ and ${\log }_{10}(\mu /\mathrm{eV})=-11.75$ which are slightly favored by the currently available data. The evidence is still weak and depends on the initial spin distribution of the black holes. No definite conclusion about the existence of ALPs could be drawn at the moment. The correlation of the ${\tau }_{\mathrm{M}}$, and the BH mass and spin is not considered in this work.

The stable secondary-to-primary flux ratios of cosmic rays (CRs), represented by the boron-to-carbon ratio (B/C), are the main probes of the galactic CR propagation. However, the fluorine-to-silicon ratio (F/Si) predicted by the CR diffusion coefficient inferred from B/C is significantly higher than the latest measurement of AMS-02. This anomaly is commonly attributed to the uncertainties of the F production cross sections. In this work, we give a careful test to this interpretation. We consider four different cross-section parametric models. Each model is constrained by the latest cross-section data. We perform combined fits to the B/C, F/Si, and cross-section data with the same propagation framework. Two of the cross-section models have good overall goodness of fit with ${\chi }^2/n_{\mathrm{d}.\mathrm{o}.\mathrm{f}.}\sim 1$. However, the goodness of fit of the cross-section part is poor with ${\chi }_{\mathrm{cs}}^2/n_{\mathrm{cs}}\gtrsim 2$ for these models. The best-fitted B production cross sections are systematically larger than the measurements, while the fitted cross sections for F production are systematically lower than the measurements. This indicates that the F anomaly can hardly be interpreted by neither the random errors of the cross-section measurements nor the differences between the existing cross-section models. We find that by developing a hypothetical parametrization this anomaly could be explained, while future measurements will test this possibility. We then propose that the spatially dependent diffusion model could help to explain B/C and F/Si consistently. In this model, the average diffusion coefficient of the Ne-Si group is expected to be larger than that of the C-O group.

Within the Color Glass Condensate (CGC) effective field theory, considering the violation of boost invariance of the rapidity distribution, we correct the normalization scheme of the longitudinal rapidity ridge correlations. After this correction, the large-rapidity ridge correlation rebounds after bottoming, consistent with the observed data from the CMS detector. It is also found that the correlation rebound appears around the sum of the saturation momentum of the projectile and target, and moves to larger rapidities at higher collision energies. These features directly result from the saturation and the quantum evolution of gluons within the framework of the CGC.

The Standard Model of particle physics and its description of nature have been recently challenged by a series of precision measurements performed via different accelerator machines. Statistically significant anomalies emerged when measuring the muon magnetic momentum, and very recently when deducing the mass of the $\mathcal{W}$ boson. Here we consider a radiative extension of the Standard Model devised to be sufficiently versatile to reconcile the various experimental results while further predicting the existence of new bosons and fermions with a mass spectrum in the TeV energy scale. The resulting spectrum is, therefore, within the energy reach of the proton-proton collisions at the LHC experiments at CERN. The model investigated here allows us to interpolate between composite and elementary extensions of the Standard Model with an emphasis on a new modified Yukawa sector that is needed to accommodate the anomalies. Focusing on the radiative regime of the model, we introduce interesting search channels of immediate impact for the ATLAS and CMS experimental programs such as the associate production of Standard Model particles with either invisible or long-lived particles. We further show how to adapt earlier supersymmetry-motivated searchers of new physics to constrain the spectrum and couplings of the new scalars and fermions. Overall, the new physics template simultaneously accounts for the bulk of the observed experimental anomalies while suggesting a wide spectrum of experimental signatures relevant for the current LHC experiments.

In this article, we examine the prospect of a first-order phase transition with a $Y=0$ real $SU(2)$ triplet extension of the Standard Model, which remains odd under $Z_2$, considering the observed Higgs boson mass, perturbative unitarity, dark matter constraints, etc. Especially, we investigate the role of Higgs-triplet quartic coupling considering one- and two-loop beta functions and compare the results with the complex singlet extension case. It is observed that, at one-loop level, no solution can be found for both, demanding Planck-scale perturbativity. However, for a much lower scale of ${10}^4\mathrm{GeV}$, the singlet case predicts a first-order phase transition consistent with the observed Higgs boson mass. On the contrary, for the two-loop beta functions with one-loop potential, both the scenarios foresee a strongly first-order phase transition consistent with the observed Higgs mass with upper bounds of 310 and 909 GeV on the triplet and singlet masses, respectively. This mass bound shifts to 259 GeV in the case of a triplet with the inclusion of two-loop contributions to the effective potential and the thermal masses with two-loop beta functions, consistent with Planck-scale perturbativity and the observed Higgs boson mass value. This puts the triplet in apparent contradiction with the observed dark matter relic bound and, thus, requires an additional field for that. The preferred regions of the parameter space in both cases are identified by benchmark points that predict gravitational waves with detectable frequencies in present and future experiments.