We show that the information of renormalization group (RG) equations are geometrically encoded into an emergent holographic dual description, which duality-transforms a $D$—dimensional quantum field theory into a $(D+1)$—dimensional classical gravity theory in the large $N$ limit, where $N$ represents the flavor degeneracy of quantum fields. First, we reformulate RG transformations in a recursive way with introduction of an order-parameter field. As a result, we manifest the RG flow of an effective field theory through the emergence of an extra dimensional space, where both RG $\beta$-functions of coupling functions and RG flow equation of the order-parameter field appear in the resulting effective action explicitly through the extra dimensional space. Second, we consider an effective dual holographic description derived recently, where the classical gravity theory of the large $N$ limit takes into account quantum corrections in the all-loop order. This nonperturbative nature turns out to originate from an intertwined renormalization structure between both RG flow equations of coupling functions and order-parameter fields in the emergent extra-dimensional space, where the IR boundary condition of the order-parameter field gives rise to a mean-field equation with fully renormalized interaction coefficients. Third, comparing the RG-reformulated effective field theory with this effective dual holographic description, we obtain term-by-term matching conditions in the level of an effective action. As a result, we express all RG coefficients of fields and interaction vertices in terms of the metric tensor of the dual holographic theory. Through this metric reformulation for the RG analysis, we propose a prescription on how to find RG $\beta$-functions of interaction coefficients in a nonperturbative way beyond the perturbative RG analysis. In particular, we claim that the present prescription of the RG flow generalizes the holographic RG flow of the holographic duality conjecture toward the absence of conformal symmetry, where the emergent holographic dual effective field theory has been derived from the first principle, thus being applicable even away from quantum criticality.

In this work we study the Tomita-Takesaki construction for a family of excited states that, in a strongly coupled CFT—at large $N$—correspond to coherent states in an asymptotically AdS spacetime geometry. We compute the modular flow and modular Hamiltonian associated to these excited states in the Rindler wedge and for a ball shaped entangling surface. Using holography, one can compute the bulk modular flow and construct the Tomita-Takesaki theory for these cases. We also discuss generalizations of the entanglement regions in the bulk and how to evaluate the modular Hamiltonian in a large N approximation. Finally, we extend the holographic Banks, Douglas, Horowitz and Matinec (BDHM) formula to compute the modular evolution of operators in the corresponding CFT algebra, and propose this as a more general prescription.

We study the explicit form of Poincaré and discrete transformations of flavor states in a two-flavor scalar model, which represents the simplest example of the field mixing. Because of the particular form of the flavor vacuum condensate, we find that the aforementioned symmetries are spontaneously broken. The ensuing vacuum stability group is identified with the Euclidean group $E(3)$. With the help of Fabri–Picasso theorem, we show that flavor vacua with different time labels and in different Lorentz frames are unitarily inequivalent to each other and they constitute a manifold of zero-flavor-charge states. Despite the spontaneous breakdown of Poincaré and $CPT$ symmetries that characterizes such vacua, we provide arguments on the absence of Goldstone Bosons. We also prove that the phenomenologically relevant oscillation formula is invariant under these transformations. In particular we prove that flavor oscillation formula on flavor vacuum has the same form in all Lorentz frames, by means of general arguments, valid at all energy scales.

It is shown that exact spherically symmetric solutions to Einstein’s field equations exist such that, over an open region of the spacetime, they are singularity free, satisfy the dominant energy condition, represent elastic matter with a well-defined constitutive function, and are such that elastic perturbations propagate causally. Two toy models are then built up in which a thick elastic, spherically symmetric shell with the above properties, separates two Robertson-Walker regions corresponding to different values of the curvature $k$ in the first model and to the same value of $k$ in the second model. The junction conditions (continuity of the first and second fundamental forms) are shown to be exactly satisfied across the corresponding matching spherical surfaces.

We study a class of higher derivative, nonlocal gravity with a cosmological constant which admits homogeneous and isotropic nonsingular bouncing universes in the absence of matter. We show that, at the linearized level around the bounce, it is possible to constrain the nonlocal form factor such that there is only a scalar propagating degree of freedom, and no vector or tensor modes. The scalar mode can be made free from perturbative ghost instabilities and has oscillatory and bounded evolution across the bounce.

We investigate the propagation of gravitational waves on a black hole background within the low-energy effective field theory of gravity, where effects from heavy fields are captured by higher-dimensional curvature operators. Depending on the spin of the particles integrated out, the speed of gravitational waves at low energy can be either superluminal or subluminal as compared to the causal structure observed by other species. Interestingly, however, gravitational waves are always exactly luminal at the black hole horizon, implying that the horizon is identically defined for all species. We further compute the corrections on quasinormal frequencies caused by the higher-dimensional curvature operators and highlight the corrections arising from the low-energy effective field.

We consider different scenarios of the evolution of the Universe, where the singularities or some nonanalyticities in the geometry of the spacetime are present, trying to answer the following question: is it possible to conserve some kind of notion of particle corresponding to a chosen quantum field present in the universe when the latter approaches the singularity? We study scalar fields with different types of Lagrangians, writing down the second-order differential equations for the linear perturbations of these fields in the vicinity of a singularity. If both independent solutions are regular, we construct the vacuum state for quantum particles as a Gaussian function of the corresponding variable. If at least one of two independent solutions has a singular asymptotic behavior, then we cannot define the creation and the annihilation operators and construct the vacuum. This means that the very notion of particle loses sense. We show that at the approaching to the big rip singularity, particles corresponding to the phantom scalar field driving the evolution of the universe must vanish, while particles of other fields still can be defined. In the case of the model of the universe described by the tachyon field with a special trigonometric potential, where the big brake singularity occurs, we see that the (pseudo) tachyon particles do not pass through this singularity. Adding to this model some quantity of dust, we slightly change the characteristics of this singularity and tachyon particles survive. Finally, we consider a model with the scalar field with the cusped potential, where the phantom divide line crossing occurs. Here the particles are well defined in the vicinity of this crossing point.

We introduce TEOBiResumS_SM, an improved version of the effective-one-body (EOB) waveform model TEOBResumS for spin-aligned, coalescing black hole binaries, that includes subdominant gravitational waveform modes completed through merger and ringdown. Beyond the dominant $(\ell ,|m|)=(2,2)$ one, the more robust multipoles all over the parameter space are: (2, 1), (3, 3), (3, 2), (4, 4), and (5, 5). Modes as (3, 1), (4, 3), and (4, 2) can also be generated, but are less robust. The multipolar ringdown EOB waveform stems from suitably fitting many numerical relativity (NR) waveform data from the Simulating eXtreme Spacetimes (SXS) collaboration together with test-mass waveform data. Mode-mixing effects are not incorporated. The orbital (nonspinning) part of the multipolar waveform amplitudes includes test-mass results up to (relative) 6PN order and, for most modes, is Padé resummed. The $m=\mathrm{odd}$ waveform multipoles (up to $\ell =5$) incorporate most of the currently available spin-dependent analytical information. Each multipolar amplitude is additionally orbital-factorized and resummed. Improving on previous work, we confirm that certain $m=\mathrm{odd}$ modes, e.g., the (2, 1), and even the (3, 1), may develop a zero (or a minimum) in the amplitude for nearly equal-mass binaries and for several combinations of the individual spins. A remarkable EOB/NR agreement around such zero is found for these modes. The new waveform, and radiation reaction, prompts a new NR-calibration of the spinning sector of the model, done with only 32 datasets. The maximum (2, 2) EOB/NR unfaithfulness $\overline{F}$ with Advanced LIGO noise against the SXS catalog ($\sim 595$ datasets) is always below 0.5% for binaries with total mass $M$ as $10M_{\odot }\le M\le 200M_{\odot }$, except for a single outlier with $\max (\overline{F})\sim 0.85\%$. When (2, 1), (3, 3) and (4, 4) modes are included, one finds an excellent EOB/NR agreement up to $M\sim 120M_{\odot }$, above which the performance degrades slightly and moves above 3% We also point out that the EOB dynamics may develop unphysical features for large, antialigned, spins and this may impact the correct construction of the (2, 1) mode in some corners of the parameter space.

Our Universe has an arrow of time. In accordance with the second law of thermodynamics, entropy has been increasing ever since the big bang. The fact that matter is in thermal equilibrium in the very early Universe, as indicated by the cosmic microwave background, has led to the idea that gravitational entropy must be very low in the beginning. Penrose proposed that gravitational entropy can be quantified by the Weyl curvature, which increases as structures form. A concrete realization of such a measure is the Clifton-Ellis-Tavakol gravitational entropy, which has been shown to be increasing in quite a number of cosmological models. In this work, we show a counterexample involving a class of inhomogeneous universes that are supported by a chameleon massless scalar field and exhibit anisotropic spacetime shearing effects. In fact, in our model the Clifton-Ellis-Tavakol gravitational entropy is increasing although the magnitude of the Weyl curvature is decreasing; this is due to the growth of the spacetime shear. The topology and the values of the three free parameters of the model are constrained by imposing a positive energy density for the cosmic fluid, and the thermodynamical requirements which follow from the cosmological holographic principle and the second law. It is shown that a negative deceleration parameter and a time-decreasing Weyl curvature automatically follow from those conditions. Thus, we argue that our model can account for the formation of some primordial structures, like the large quasar groups, which has required a nonstandard evolution of the spatial anisotropies.

It has been recently established that, if the nonlinear relationship between the overdensity perturbations and the curvature perturbations are taken into account, non-Gaussianity is introduced in the overdensity statistics, which alters the expected primordial black hole abundance. This is explored by using the nonlinear relationship between the overdensities and curvature perturbations up to second order, where a negative skewness and positive kurtosis aim at lowering and increasing the abundance, while an abundance comparable to Gaussian perturbations is obtained by adjusting the amplitude of the curvature power spectrum. The effects of the nonvanishing skewness and kurtosis are studied using a toy model Dirac delta and log-normal curvature power spectra as well as one obtained from an $\alpha$-attractor model capable of primordial black hole production. Finally, the nonlinear calculations using Press-Schechter are compared with peaks theory.

Thermal freeze-out is a prominent example of dark matter (DM) production mechanism in the early Universe that can yield the correct relic density of stable weakly interacting massive particles (WIMPs). At the other end of the mass scale, many popular extensions of the Standard Model predict the existence of ultralight scalar fields. These can be coupled to matter, preferentially in a universal and shift-symmetry-preserving way. We study the impact of such conformal and disformal couplings on the relic density of WIMPs, without introducing modifications to the thermal history of the Universe. This can either result in an additional thermal contribution to the DM relic density or suppress otherwise too large abundances compared to the observed levels. In this work, we assume that the WIMPs only interact with the standard model via the light scalar portal. We use simple models of fermionic or scalar DM, although a similar discussion holds for more sophisticated scenarios, and predict that their masses should be between $\sim 100\mathrm{GeV}$ and several TeV to comply both with the DM abundance and current bounds on the couplings of the light scalars to matter at the LHC. Future searches will tighten these bounds.

The Pierre Auger collaboration has provided a compelling indication for a possible correlation between the arrival directions of ultrahigh-energy cosmic rays and nearby starburst galaxies. Herein we show how the latest large-scale modeling of starburst galaxies is compatible with the cosmic rays producing the anisotropy signal being accelerated at the terminal shock of superwinds.

The Laser Interferometer Space Antenna (LISA) is slated for launch in the early 2030s. A main target of the mission is massive black hole binaries that have an expected detection rate of $\sim 20{\mathrm{yr}}^{-1}$. We present a parameter estimation analysis for a variety of massive black hole binaries. This analysis is performed with a graphics processing unit (GPU) implementation comprising the phenomhm waveform with higher-order harmonic modes and aligned spins; a fast frequency-domain LISA detector response function; and a GPU-native likelihood computation. The computational performance achieved with the GPU is shown to be 500 times greater than with a similar CPU implementation, which allows us to analyze full noise-infused injections at a realistic Fourier bin width for the LISA mission in a tractable and efficient amount of time. With these fast likelihood computations, we study the effect of adding aligned spins to an analysis with higher-order modes by testing different configurations of spins in the injection, as well as the effect of varied and fixed spins during sampling. Within these tests, we examine three different binaries with varying mass ratios, redshifts, sky locations, and detector-frame total masses ranging over 3 orders of magnitude. We discuss varied correlations between the total masses and mass ratios; unique spin posteriors for the larger mass binaries; and the constraints on parameters when fixing spins during sampling, allowing us to compare to previous analyses that did not include aligned spins.

The ideal magnetohydrodynamic theorem on the conservation of the magnetic connections between plasma elements is extended to nonideal relativistic plasmas in curved spacetime. The existence of generalized magnetofluid connections that are preserved by the plasma dynamics is formalized by means of a covariant connection equation that includes different nonideal effects. These generalized connections are constituted by 2-dimensional hypersurfaces, which are linked to an antisymmetric tensor field that unifies the electromagnetic and fluid fields. They can be interpreted in terms of generalized magnetofluid vorticity field lines by considering a $3+1$ foliation of spacetime and a time resetting projection that compensates for the loss of simultaneity between spatially separated events. The worldsheets of the generalized magnetofluid vorticity field lines play a fundamental role in the plasma dynamics by prohibiting evolutions that do not preserve the magnetofluid connectivity.

The detection of gravitational waves provides us with a deep insight into the Universe. In order to increase the number of detectable gravitational-wave sources, several future gravitational-wave detectors will operate with cryogenic mirrors. Recent studies, however, showed that residual gas molecules inside the vacuum chamber adhere to the cryogenic mirror surface and form a molecular layer which grows with time. This growing molecular layer introduces an additional optical loss in the mirror which can decrease the detector’s performance. We theoretically estimate the optical loss by the molecular layer in a cryogenically operated gravitational-wave detector. The impact on a cryogenic gravitational-wave detector is discussed based on the results of the optical loss estimation.

Recently the renormalization of the band gap $m$, in both tungsten diselenide (${\mathrm{WSe}}_2$) and molybdenumm disulfide (${\mathrm{MoS}}_2$), has been experimentally measured as a function of the carrier concentration $n$. The main result establishes a decreasing of hundreds of meV, in comparison with the bare band gap, as the carrier concentration increases. These materials are known as transition metal dichalcogenides and their low-energy excitations are, approximately, described by the massive Dirac equation. Using pseudo–quantum electrodynamics (PQED) to describe the electromagnetic interaction between these quasiparticles and from renormalization group analysis at the large-$N$ limit, we obtain that the renormalized mass describes the band gap renormalization with a function given by $m(n)/m_0=(n/n_0{)}^{C_{\lambda }/2}$, where $m_0=m(n_0)$ and $C_{\lambda }$ is a function of the coupling constant $\lambda =\pi \alpha /4$, where $\alpha$ is the fine-structure constant. We compare our theoretical results with the experimental findings for ${\mathrm{WSe}}_2$ and ${\mathrm{MoS}}_2$, and we conclude that our approach is in agreement with these experimental results for reasonable values of $\lambda$. Thereafter, we consider the coupling of massless Dirac particles with the Gross-Neveu interaction, which generates a mass for the Dirac field through the gap equation, and PQED. In this case, we show that there exists a critical coupling constant, namely, ${\lambda }_c\approx 0$, 66 in which the beta function of the mass vanishes, providing a stable fixed point in the ultraviolet limit. For $\lambda >{\lambda }_c$, the renormalized mass decreases while for $\lambda <{\lambda }_c$ it increases with the carrier concentration.

In this work, we provide a simultaneous and accurate description of the ${\pi }^{+}{\pi }^{-}$ and ${\pi }^{\pm }J/\psi$ invariant mass distributions of the recent BESIII data on $e^{+}{e}^{-}\to J/\psi {\pi }^{+}{\pi }^{-}$, together with the $e^{+}{e}^{-}\to J/\psi K^{+}{K}^{-}$ cross sections at $e^{+}{e}^{-}$ center-of-mass energies $q=4.23\mathrm{GeV}$ and $q=4.26\mathrm{GeV}$. The rescattering effects between pions in the S and D waves are taken into account through the Muskhelishvili-Omnès formalism. Since the physical region of the $\pi \pi$ invariant mass extends above 1 GeV, the important $K\overline{K}$ intermediate state in the S wave is implemented through coupled-channel unitarity. For the left-hand cuts, we account for the well established charged exotic state $Z_c(3900)$ in $t$ and $u$ channels, while the other contributions are absorbed in the subtraction constants. For the $e^{+}{e}^{-}\to J/\psi K\overline{K}$, we provide the prediction of the two-kaon invariant mass distribution. The constructed amplitudes serve as an essential framework to interpret the present and forthcoming measurements by the BESIII and Belle II Collaborations.

Higher-order tree-level processes in strong laser fields, i.e., cascades, are in general extremely difficult to calculate, but in some regimes the dominant contribution comes from a sequence of first-order processes, i.e., nonlinear Compton scattering and nonlinear Breit-Wheeler pair production. At high intensity the field can be treated as locally constant, which is the basis for standard particle-in-cell codes. However, the locally-constant-field (LCF) approximation and these particle-in-cell codes cannot be used when the intensity is only moderately high, which is a regime that is experimentally relevant. We have shown that one can still use a sequence of first-order processes to estimate higher orders at moderate intensities provided the field is sufficiently long. An important aspect of our new “gluing” approach is the role of the spin and polarization of intermediate particles, which is more nontrivial compared to the LCF regime.

We examine a simple extension of the standard model with a pair of fermions, one singlet and a doublet, in a common thread linking the dark matter problem with the smallness of neutrino masses associated with several exciting features. In the presence of a small bare Majorana mass term, the singlet fermion brings in a pseudo-Dirac dark matter capable of evading the strong spin-independent direct detection bound by suppressing the dark matter annihilation processes mediated by the neutral current. In consequence, the allowed range of a mixing angle between the doublet and the singlet fermions gets enhanced substantially. The presence of the same mass term in an association with singlet scalars also elevates tiny but nonzero masses radiatively for light Majorana neutrino satisfying observed oscillation data.

Axion models with generation-dependent Peccei-Quinn charges can lead to flavor-changing neutral currents, thus motivating QCD axion searches at precision flavor experiments. We rigorously derive limits on the most general effective flavor-violating couplings from current measurements and assess their discovery potential. For two-body decays, we use available experimental data to derive limits on $q\to q^{\prime }a$ decay rates for all flavor transitions. Axion contributions to neutral-meson mixing are calculated in a systematic way using chiral perturbation theory and operator product expansion. We also discuss in detail baryonic decays and three-body meson decays, which can lead to the best search strategies for some of the couplings. For instance, a strong limit on the $\mathrm{\Lambda }\to na$ transition can be derived from the supernova SN 1987A. In the near future, dedicated searches for $q\to q^{\prime }a$ decays at ongoing experiments could potentially test Peccei-Quinn breaking scales up to ${10}^{12}\mathrm{GeV}$ at NA62 or KOTO and up to ${10}^9\mathrm{GeV}$ at Belle II or BES III.