We combine the NNLO QCD description of Higgs boson production in association with an electroweak vector boson $V=W$ or $Z$ with a similarly precise description of Higgs boson decays into a pair of massive $b$ quarks and with the anomalous couplings that modify interactions of the Higgs and electroweak vector bosons. The resulting numerical code provides the most advanced theoretical tool to investigate such anomalous couplings in the associated Higgs boson production process. We study the impact of anomalous couplings on fiducial cross sections and differential distributions and argue that, with increased QCD precision, smaller anomalous couplings become accessible in kinematic regions where the effects of higher-dimensional operators in the Standard Model effective field theory remain small and the effective field theory expansion is under control.

We study the important, yet widely overlooked, role of gluons for spin transport with a connection to local parity violation in quark gluon plasmas. We employ the formalism of quantum kinetic theory to quarks in weakly coupled quantum chromodynamics to derive the source terms for quark spin polarization. These source terms involve parity-odd correlators of dynamically generated color fields in near-equilibrium quark gluon plasmas and give rise to locally fluctuating axial charge currents. Our results provide a possible explanation for the spin alignment of vector mesons measured in high-energy nuclear collisions.

Incompleteness in current knowledge of neutrino interactions with nuclear matter imposes a primary limitation in searches for leptonic $CP$ violation carried out at long-baseline neutrino experiments. In this paper, we present a new computation that elevates the theoretical accuracy to next-to-next-to-leading order in QCD for charged-current deeply inelastic scattering processes relevant for ongoing and future neutrino programs. Mass-dependent quark contributions are consistently included across a wide range of momentum transfers in the simplified-ACOT-$\chi$ general-mass scheme. When appropriate, we further include next-to-next-to-next-to-leading order corrections in the zero-mass scheme. We show theoretical predictions for several experiments with neutrinos over a wide range of energies and at the upcoming electron-ion collider. Our prediction reduces perturbative uncertainties to $\sim 1\%$, sufficient for the high-precision objectives of future charged-current deeply inelastic scattering measurements, and provides important theoretical inputs to experimental studies of leptonic mixing and $CP$ violations.

We study the effective low energy dynamics of the topologically twisted super Yang-Mills theory on compact four-manifolds that support surface defects where the gauge field becomes singular along certain directions. Following recent work on the topic of $u$-plane integrals in topological theories, we show that the integrand of the path integral can be expressed in terms of mock modular forms, which allows the evaluation of correlation functions using Stokes’ theorem.

We refine the calculation of holographic complexity of black holes in the complexity equals action approach by applying the recently introduced criterion that the action of any causal diamond in static vacuum regions must vanish identically. This criterion fixes empty anti–de Sitter (AdS) spacetime as the reference state with vanishing complexity and renders holographic complexity explicitly finite in all the cases we consider. The cases considered here include the Reissner-Nordström-AdS black hole, the rotating BTZ black hole, the Kerr-AdS black hole, and AdS-Vaidya spacetime. The criterion is equivalent to imposing that the corner contributions vanish. Contrary to earlier results, we find that the generalized Lloyd bound always holds in the Reissner-Nordström-AdS and BTZ cases.

We calculate the tree-level partition function of a Euclidean Bañados-Teitelboim-Zanelli (BTZ) black hole in the presence of end of the world branes (ETW branes) and the one-loop partition function of a Euclidean thermal ${\mathrm{AdS}}_3$ in the presence of an ETW brane. At the tree level, our results match with the previous ones for static BTZ black holes. Interestingly, at the one-loop level, our results contain novel terms, which reflect the existence of an ETW brane. The ETW brane has a consistent profile for a static thermal AdS and, in this case, we showed that the spectrum obtained from the one-loop partition function takes a physically sensible form.

Kontsevich and Segal (K-S) have proposed a criterion to determine which complex metrics should be allowed, based on the requirement that quantum field theories may consistently be defined on these metrics, and Witten has recently suggested that their proposal should also apply to gravity. We explore this criterion in the context of gravitational path integrals, in simple minisuperspace models, specifically considering de Sitter (dS), no-boundary and anti–de Sitter (AdS) examples. These simple examples allow us to gain some understanding of the off-shell structure of gravitational path integrals. In all cases, we find that the saddle points of the integral lie right at the edge of the allowable domain of metrics, even when the saddle points are complex or Euclidean. Moreover the Lefschetz thimbles, in particular the steepest descent contours for the lapse integral, are cut off as they intrude into the domain of nonallowable metrics. In the AdS case, the implied restriction on the integration contour is found to have a simple physical interpretation. In the dS case, the lapse integral is forced to become asymptotically Euclidean. We also point out that the K-S criterion provides a reason, in the context of the no-boundary proposal, for why scalar fields would start their evolution at local extrema of their potential.

We consider the order parameter $u=⟨\mathrm{Tr}{\varphi }^2⟩$ as a function of the running coupling constant $\tau \in \mathbb{H}$ of asymptotically free $\mathcal{N}=2$ QCD with gauge group $SU(2)$ and $N_f\le 3$ massive hypermultiplets. If the domain for $\tau$ is restricted to an appropriate fundamental domain ${\mathcal{F}}_{N_f}$, then the function $u$ is one to one. We demonstrate that these domains consist of six or less images of an $\mathrm{SL}(2,\mathbb{Z})$ keyhole fundamental domain, with appropriate identifications of the boundaries. For special choices of the masses, $u$ does not give rise to branch points and cuts, such that $u$ is a modular function for a congruence subgroup $\mathrm{\Gamma }$ of $\mathrm{SL}(2,\mathbb{Z})$ and the fundamental domain is $\mathrm{\Gamma }\backslash \mathbb{H}$. For generic masses, however, branch points and cuts are present, and subsets of ${\mathcal{F}}_{N_f}$ are being cut and glued upon varying the mass. We study this mechanism for various phenomena, such as the decoupling of hypermultiplets, the merging of local singularities, as well as the merging of nonlocal singularities which give rise to superconformal Argyres-Douglas theories.

Two codimensional thick braneworlds are investigated in quite general terms for two intersecting scalar fields generating the extra dimension defect. In general, when one considers two codimensional thick braneworlds, the warp factor is constructed as a stringlike defect. Considering a twofold warp factor constructed from two intersecting warp factors, an alternative bulk configuration is examined. With the brane localization thus driven by two crossing scalar fields, the possible solvable models obtained from such a two codimensional setup are systematically discussed. The obtained solutions are classified as five different models organized into two subsets, for which some of their physical properties are evaluated. For models $I$ and $II$, in the first subset, Einstein equation solutions are rigidly defined, up to some arbitrary constant. For models $III$, $IV$, and $V$, in the second subset, an additional degree of freedom not constrained by Einstein equations is admitted. The solutions are all obtained from a departure statement of assuming a conformally flat metric for the internal space, which is concomitant to the proper choice of coordinates. Eventual singularities in the curvature are identified, however, without affecting the physical appeal of the solutions described in terms of the stress energy tensor patterns, which are shown to be free of singularities for model $IV$, besides admitting straightforward reductions to ($4+1$) dimensions. In particular, from the framework of models $III$ and $IV$, one is able to achieve braneworld solutions over two different geometries of ${\mathbb{S}}^2$ which, as demonstrated, can be reduced to trivial and nontrivial extensions of the well-known ($4+1$)-dimensional braneworlds. Therefore, our ($5+1$)-dimensional results point to a consistent and expanded generalization of a ($4+1$)-dimensional braneworld which naturally admits the possibility of an enlarged and maybe more accurate phenomenology.

We prove two theorems which imply that any stationary nonlinear electromagnetic field obeying a dominant energy condition in a strictly stationary, everywhere regular, asymptotically flat spacetime must be either trivial or a stealth field. The first theorem holds in static spacetimes and is independent of the gravitational part of the action, as long as the coupling of the electromagnetic field to the gravitational field is minimal. The second theorem assumes Einstein–Hilbert gravitational action and relies on the positive energy theorem, but does not assume that the spacetime metric is static. In addition, we discuss possible generalizations of these results, to theories with charged matter, as well as higher-dimensional nonlinear electromagnetic fields.

We present a general framework for studying the relativistic star perturbations on a static and spherically symmetric background in full Horndeski theories. We take a perfect fluid into account as a form of the Schutz-Sorkin action. Our formulation is sufficiently versatile in that the second-order actions of perturbations in odd- and even-parity sectors are derived without choosing particular gauge conditions, so they can be used for any convenient gauges at hand. The odd-parity sector contains one dynamical gravitational degree of freedom coupled to a time-independent four velocity of the fluid. In the even-parity sector there are three dynamical perturbations associated with gravity, scalar field, and matter sectors, whose equations of motion are decoupled from other nondynamical perturbations. For high radial and angular momentum modes, we obtain the propagation speeds of all dynamical perturbations and show that the perfect fluid in the even-parity sector has a standard sound speed affected by neither gravity nor the scalar field. Our general stability conditions and perturbation equations of motion can be directly applied to the stabilities of neutron stars and black holes as well as the calculations of their quasinormal frequencies.

According to a more recent $\mathrm{AdS}/\mathrm{CFT}$ interpretation [A. Karch and B. Robinson, J. High Energy Phys. 12 (2015) 073] in which varying cosmological constant $\mathrm{\Lambda }$ in the bulk corresponds to varying the curvature radius governing the space on which the field theory resides, we study the criticality of thermodynamic curvatures for thermal boundary conformal field theories (CFT) that are dual to $d$-dimensional charged anti–de Sitter (AdS) black holes, embedded in $D$-dimensional M-theory/superstring inspired models having ${\mathrm{AdS}}_d\times {\mathbb{S}}^{d+k}$ spacetime with $D=2d+k$. Analogous with criticality features acquired for charged AdS black holes in the bulk [S. A. Hosseini Mansoori et al., Phys. Rev. D 102, 124066 (2020)], the normalized intrinsic curvature $R_N$ and extrinsic curvature $K_N$ of the boundary CFT has critical exponents 2 and 1, respectively. In this respect, the universal amplitude of $R_N{t}^2$ is $\frac{1}{2}$ and $K_{N}t$ is $-\frac{1}{2}$ when $t\to 0^{-}$, whereas $R_N{t}^2\approx \frac{1}{8}$ and $K_{N}t\approx \frac{1}{4}$ in the limit $t\to 0^{+}$ in which $t=T/T_c-1$ is the temperature parameter with the critical temperature, $T_c$. Interestingly, these critical amplitudes are independent of the number of thermal CFT dimensions and are remarkably similar to one given for higher dimensional charged AdS black holes in the bulk.

In recent papers it has been shown that a large class of vectorization mechanisms in gravity, which involve the vector fields becoming apparently tachyonic in some regime, are actually dominated by ghosts and nonperturbative behavior. Despite this, vectorized compact object solutions have previously been found, which raises the question of how, and if, the newly discovered ghosts are quenched in these cases. Here we develop the tools to study the perturbations of vectorized compact objects, and demonstrate that they suffer from ghosts and gradient instabilities as well. Thus, these vectorized objects do not represent the stable end point of a quenched instability unlike their scalarized counterparts in the spontaneous scalarization literature.

We discuss new consistency relations for single field models of inflation capable of generating primordial black holes (PBH), and their observational implications for CMB $\mu$-space distortions. These inflationary models include a short period of nonattractor evolution; the scale-dependent profile of curvature perturbation is characterized by a pronounced dip, followed by a rapid growth leading to a peak responsible for PBH formation. We investigate the squeezed and the collapsed limits of three- and four-point functions of curvature perturbation around the dip, showing that they satisfy consistency relations connecting their values to the total amplification of the curvature spectrum, and to the duration of the nonattractor era. Moreover, the corresponding non-Gaussian parameters are scale dependent in proximity of the dip, with features that again depend on the amplification of the spectrum. For typical PBH scenarios requiring an order $\mathcal{O}({10}^7)$ enhancement of the spectrum from large towards small scales, we generally find values $f_{\mathrm{NL}}^{\mathrm{sq}}=\mathcal{O}(10)$ and ${\tau }_{\mathrm{NL}}^{\mathrm{col}}=\mathcal{O}({10}^3)$ in a range of scales that can be probed by CMB $\mu$-space distortions. Using these consistency relations, we carefully analyze how the scale-dependence of non-Gaussian parameters leads to characteristic features in $⟨\mu T⟩$ and $⟨\mu \mu ⟩$ correlators, providing distinctive probes of inflationary PBH scenarios that can be tested using well-understood CMB physics.

We investigate a recently proposed method for measuring the Hubble constant from gravitational wave detections of binary black hole coalescences without electromagnetic counterparts. In the absence of a direct redshift measurement, the missing information on the left-hand side of the Hubble-Lemaître law is provided by the statistical knowledge on the redshift distribution of sources. We assume that source distribution in redshift depends on unknown hyperparameters, modeling our ignorance of the astrophysical binary black hole distribution. With tens of thousands of these “black sirens”—a realistic figure for the third generation detectors Einstein Telescope and Cosmic Explorer—an observational constraint on the value of the Hubble parameter at percent level can be obtained. This method has the advantage of not relying on electromagnetic counterparts, which accompany a very small fraction of gravitational wave detections, nor on often unavailable or incomplete galaxy catalogs.

The feature of the observed shadows and rings of an astrophysical black hole (BH) may depend on its accretion flows and magnetic charge. We find that the shadow radii and critical impact parameters of the Hayward BH are decreased with the increase of the magnetic charge. Comparing the Schwarzschild BH with the Hayward BH using the ray-tracing method, we show that the density and deflection of lights increase with the magnetic charge, and the BH singularity does not affect the generation of the shadow. Based on three optically thin accretion flow models, the two-dimensional shadows in celestial coordinates are derived. It is found that the shadow and photon ring luminosities of a Hayward BH surrounded by infalling spherical accretion flow are dimmer than that of a static spherical accretion flow. Taking three kinds of inner radii at which the accretion flow stops radiating, we find that the observed luminosity of a Hayward BH surrounded by a thin disk accretion flow is dominated by the direct emission, and the photon ring emission has a weak influence on it. These results suggest that the size of the observed shadow is related to the space-time geometry, and the luminosities of both the shadows and rings are affected by the accretion flow property and the BH magnetic charge.

Within SU(2) Higgs-Proca theory, we obtain a family of nontopological static solutions describing localized, finite-energy configurations (Proca balls). The gauge symmetry of the theory is explicitly broken by introducing a vector Proca field whose components have different masses. Such solutions describe particlelike systems, the crucial feature of which is that they either possess a nonzero total angular momentum or have a flux of electric field through the plane of symmetry of such objects. It is shown that the angular momentum is provided by static crossed electric and magnetic fields. The existence of the solutions is caused by the fact that we circumvent the conditions of the no-go theorem, according to which there are no stationary and axially symmetric spinning excitations for the ’t Hooft-Polyakov monopoles, Julia-Zee dyons, sphalerons, and also vortices. The dependence of some integral physical quantities on the ratio of the Proca-field masses is studied. It is demonstrated that the inclusion of external sources (charges) enables one to obtain solutions with equal Proca-field masses. We also discuss the possibilities of using quarks as sources of the Proca field under investigation and for treating the Proca balls as glueballs in SU(2) Higgs-Proca theory.

We solve for the critical coupling in the symmetric phase of two-dimensional ${\varphi }^4$ field theory using discretized light-cone quantization. We adopt periodic boundary conditions, neglect the zero mode, and obtain a critical coupling consistent with the critical coupling reported using conformal truncation in light-front quantization. We find a 17% difference from the critical coupling reported with light-front quantization in a symmetric polynomial basis.

We study an extension of the minimal gauged $L_{\mu }-L_{\tau }$ model including three right-handed singlet fermions and a scalar doublet to explain the anomalous magnetic moments of muon and electron simultaneously. The presence of an in-built $Z_2$ symmetry under which the right-handed singlet fermions and $\eta$ are odd, gives rise to a stable dark matter candidate along with light neutrino mass in a scotogenic fashion. In spite of the possibility of having positive and negative contributions to muon and electron ($g-2$) respectively from vector boson and charged scalar loops, the minimal scotogenic $L_{\mu }-L_{\tau }$ model cannot explain both muon and electron ($g-2$) simultaneously while being consistent with other experimental bounds. We then extend the model with a vectorlike lepton doublet which not only leads to a chirally enhanced negative contribution to electron ($g-2$) but also leads to the popular singlet-doublet fermion dark matter scenario. With this extension, the model can explain both electron and muon ($g-2$) while being consistent with neutrino mass, dark matter and other direct search bounds. The model remains predictive at high energy experiments like collider as well as low energy experiments looking for charged lepton flavor violation, dark photon searches, in addition to future ($g-2$) measurements.

We perform a model-exhaustive analysis of all possible beyond Standard Model (BSM) solutions to the $(g-2{)}_{\mu }$ anomaly to study production of the associated new states at future muon colliders, and we formulate a no-lose theorem for the discovery of new physics if the anomaly is confirmed and weakly coupled solutions below the GeV scale are excluded. Our goal is to find the highest possible mass scale of new physics subject only to perturbative unitarity, and optionally the requirements of minimum flavor violation and/or naturalness. We prove that a 3 TeV muon collider is guaranteed to discover all BSM scenarios in which $\mathrm{\Delta }{a}_{\mu }$ is generated by SM singlets with masses above $\sim \mathrm{GeV}$; lighter singlets will be discovered by upcoming low-energy experiments. If new states with electroweak quantum numbers contribute to $(g-2{)}_{\mu }$, then the minimal requirements of perturbative unitarity guarantee new charged states below $\mathcal{O}(100\mathrm{TeV})$, but this is strongly disfavoured by stringent constraints on charged lepton flavor violating (CLFV) decays. Reasonable BSM theories that satisfy CLFV bounds by obeying minimal flavor violation and avoid generating two new hierarchy problems require the existence of at least one new charged state below $\sim 10\mathrm{TeV}$. This strongly motivates the construction of high-energy muon colliders, which are guaranteed to discover new physics: either by producing these new charged states directly, or by setting a strong lower bound on their mass, which would empirically prove that the Universe is fine-tuned and violates the assumptions of minimal flavor violation while somehow not generating large CLFVs. The former case is obviously the desired outcome, but the latter scenario would perhaps teach us even more about the Universe by profoundly revising our understanding of naturalness, cosmological vacuum selection, and the SM flavor puzzle.