The change in holographic entanglement entropy (HEE) for small fluctuations about pure anti-de Sitter (AdS) is obtained by a perturbative expansion of the area functional in terms of the change in the bulk metric and the embedded extremal surface. However it is known that change in the embedding appears at second order or higher. It was shown that these changes in the embedding can be calculated in the $2+1$ dimensional case by solving a “generalized geodesic deviation equation.” We generalize this result to arbitrary dimensions by deriving an inhomogeneous form of the Jacobi equation for minimal surfaces. The solutions of this equation map a minimal surface in a given space time to a minimal surface in a space time which is a perturbation over the initial space time. Using this we perturbatively calculate the changes in HEE up to second order for boosted black brane like perturbations over ${\mathrm{AdS}}_4$.

We introduce a more general set of kinematic renormalization schemes than the original momentum subtraction schemes of Celmaster and Gonsalves. These new schemes will depend on a parameter $\omega$, which tags the external momentum of one of the legs of the three-point vertex functions in QCD. In each of the three new schemes, we renormalize QCD in the Landau and maximal Abelian gauges and establish the three-loop renormalization group functions in each gauge. For an application, we evaluate two critical exponents at the Banks-Zaks fixed point and demonstrate that their values appear to be numerically scheme independent in a subrange of the conformal window.

We propose a radiative neutrino-mass model by introducing 3 generations of fermion pairs $E^{-(N+1)/2}{E}^{+(N+1)/2}$ and a couple of multicharged bosonic doublet fields ${\mathrm{\Phi }}_{N/2},{\mathrm{\Phi }}_{N/2+1}$, where $N=1$, 3, 5, 7, 9. We show that the models can satisfy the neutrino masses and oscillation data, and are consistent with lepton-flavor violations, the muon anomalous magnetic moment, the oblique parameters, and the beta function of the $U(1{)}_Y$ hypercharge gauge coupling. We also discuss the collider signals for various $N$, namely, multicharged leptons in the final state from the Drell-Yan production of $E^{-(N+1)/2}{E}^{+(N+1)/2}$. In general, the larger the $N$ the more charged leptons will appear in the final state.

We discuss lepton number violation in three units. From an effective field theory point of view, $\mathrm{\Delta }L=3$ processes can only arise from dimension 9 or higher operators. These operators also violate baryon number, hence many of them will induce proton decay. Given the high dimensionality of these operators, in order to have a proton half-life in the observable range, the new physics associated to $\mathrm{\Delta }L=3$ processes should be at a scale as low as 1 TeV. This opens up the possibility of searching for such processes not only in proton decay experiments but also at the LHC. In this work we analyze the relevant $d=9$, 11, 13 operators which violate lepton number in three units. We then construct one simple concrete model with interesting low- and high-energy phenomenology.

Many extensions of the standard model contain an extra $U(1{)}^{\prime }$ gauge group with a heavy $Z^{\prime }$ gauge boson. Perhaps the most clear signal for such a $Z^{\prime }$ would be a resonance in the invariant mass spectrum of the lepton pairs to which it decays. In the absence of such a signal, experiments can set limits on the couplings of such a $Z^{\prime }$, using a standard formula from theory. We repeat its derivation and find that, unfortunately, the standard formula in the literature is a factor of 8 too small. We briefly explore the implication for existing experimental searches and encourage the high-energy physics community to reexamine analyses that have used this formula.

Non-Abelian gauge theories with fermions transforming in the adjoint representation of the gauge group (AdjQCD) are a fundamental ingredient of many models that describe the physics beyond the Standard Model. Two relevant examples are $\mathcal{N}=1$ supersymmetric Yang-Mills (SYM) theory and minimal walking technicolor, which are gauge theories coupled to one adjoint Majorana and two adjoint Dirac fermions, respectively. While confinement is a property of $\mathcal{N}=1$ SYM, minimal walking technicolor is expected to be infrared conformal. We study the propagators of ghost and gluon fields in the Landau gauge to compute the running coupling in the MiniMom scheme. We analyze several different ensembles of lattice Monte Carlo simulations for the SU(2) adjoint QCD with $N_f=1/2,1,3/2$, and 2 Dirac fermions. We show how the running of the coupling changes as the number of interacting fermions is increased towards the conformal window.

We propose a method to compute the Wilson coefficients of the weak effective Hamiltonian to all orders in the strong coupling constant using Lattice QCD simulations. We perform our calculations adopting an unphysically light weak boson mass of around 2 GeV. We demonstrate that systematic errors for the Wilson coefficients $C_1$ and $C_2$, related to the current-current four-quark operators, can be controlled and present a path towards precise determinations in subsequent works.

We compare the rapidity, $y$, and the beam energy, $\sqrt{s}$, behaviors of the cross section of the data for $D$ meson production in the forward direction that were measured by the LHCb Collaboration. We describe the observed cross sections using NLO perturbative QCD, and choose the optimal factorization scale for the LO contribution which provides the resummation of the large double logarithms. We emphasize the inconsistency observed in the $y$ and $\sqrt{s}$ behaviors of the $D$ meson cross sections. The $y$ behavior indicates a very flat $x$ dependence of the gluon PDF in the unexplored low $x$ region around $x\sim 10^{-5}$. However, to describe the $\sqrt{s}$ dependence of the data we need a steeper gluon PDF with decreasing $x$. Moreover, an even steeper behavior is needed to provide an extrapolation which matches on to the well known gluons found in the global PDF analyses for $x\sim 10^{-3}$. The possible role of nonperturbative effects is briefly discussed.

We investigate a tunneling and emission process of a thin-shell from a Schwarzschild black hole, where the shell was initially located beyond the Einstein-Rosen bridge and finally appears at the right side of the Penrose diagram. In order to obtain such a solution, we should assume that the areal radius of the black hole horizon increases after the tunneling. Hence, there is a parameter range such that the tunneling rate is exponentially enhanced, rather than suppressed. We may have two interpretations regarding this. First, such a tunneling process from the past horizon is improbable by physical reasons; second, such a tunneling is possible in principle, but in order to obtain a stable Einstein-Rosen bridge, one needs to restrict the parameter spaces. If such a process is allowed, this can be a nonperturbative contribution to Einstein-Rosen bridges as well as eternal black holes.

In this article, we consider an ad hoc deformation of the Engle-Livine-Pereira-Rovelli model for quantum gravity by a cosmological constant term. This sort of deformation was first introduced by Han for the case of the 4-simplex. In this article, we generalize the deformation to the case of arbitrary vertices, and compute its large-$j$ asymptotics. We show that, if the boundary data correspond to a four-dimensional polyhedron $P$, then the asymptotic formula gives the usual Regge action plus a cosmological constant term. We pay particular attention to the determinant of the Hessian matrix, and show that it can be related to that of the undeformed vertex.

We propose a quantum version of the quadratic volume simplicity constraint for the Engle-Livine-Pereira-Rovelli spin foam model. It relies on a formula for the volume of 4-dimensional polyhedra, depending on its bivectors and the knotting class of its boundary graph. While this leads to no further condition for the 4-simplex, the constraint becomes nontrivial for more complicated boundary graphs. We show that, in the semiclassical limit of the hypercuboidal graph, the constraint turns into the geometricity condition observed recently by several authors.

The need for a consistent quantum evolution for black holes has led to proposals that their semiclassical description is modified not just near the singularity, but at horizon or larger scales. If such modifications extend beyond the horizon, they influence regions accessible to distant observation. Natural candidates for these modifications behave like metric fluctuations, with characteristic length scales and timescales set by the horizon radius. We investigate the possibility of using the Event Horizon Telescope to observe these effects, if they have a strength sufficient to make quantum evolution consistent with unitarity, without introducing new scales. We find that such quantum fluctuations can introduce a strong time dependence for the shape and size of the shadow that a black hole casts on its surrounding emission. For the black hole in the center of the Milky Way, detecting the rapid time variability of its shadow will require nonimaging timing techniques. However, for the much larger black hole in the center of the M87 galaxy, a variable black-hole shadow, if present with these parameters, would be readily observable in the individual snapshots that will be obtained by the Event Horizon Telescope.

A new approximation is proposed for the contour of the stationary phase of the Mellin-Barnes integrals in the case of its finite asymptotic behavior as $\mathrm{Re}z\to -\infty$. The efficiency of application of the proposed contour and the quadratic approximation to the contour of the stationary phase is compared to the example of the inverse Mellin transform for the structure function $F_3$. It is shown that, although for a small number of terms $N$ in quadrature formulas used to calculate integrals along these contours, the quadratic contour is more efficient, but for $N>20$ the asymptotic stationary phase integration contour gives better accuracy. The case of the $Q^2$ dependence of the $F_3$ structure function is also considered.

We revisit correlations of neutrino oscillation parameters in reactor and long-baseline neutrino oscillation experiments. A framework based on an effective value of ${\theta }_{13}$ is presented, which can be used to analytically study the correlations and explain some questions including why and when ${\delta }_{CP}$ has the best fit value of $-\pi /2$, why current and future long-baseline experiments will have less precision of ${\delta }_{CP}$ around $\pm \pi /2$ than that around zero, etc. Recent hints on the $CP$ phase are then considered from the point of view that different reactor and long-baseline neutrino experiments provide currently different best-fit values of ${\theta }_{13}$ and ${\theta }_{23}$. We point out that the significance of the hints changes for the different available best-fit values.

Twist fields were introduced a few decades ago as a quantum counterpart to classical kink configurations and disorder variables in low dimensional field theories. In recent years they received a new incarnation within the framework of geometric entropy and strong coupling limit of four-dimensional scattering amplitudes. In this paper, we study their two-point correlation functions in a free massless scalar theory, namely, twist-twist and twist-antitwist correlators. In spite of the simplicity of the model in question, the properties of the latter are far from being trivial. The problem is reduced, within the formalism of the path integral, to the study of spectral determinants on surfaces with conical points, which are then computed exactly making use of the zeta function regularization. We also provide an insight into twist correlators for a massive complex scalar by means of the Lifshitz-Krein trace formula.

We perform an analysis of models of chaotic inflation where the inflaton field $\varphi$ is coupled nonminimally to gravity via $\xi {\varphi }^n{g}^{\mu \nu }{R}_{\mu \nu }(\mathrm{\Gamma }),n>0$. We focus on the Palatini theory of gravity, i.e., the case where the assumptions of general relativity are relaxed (that of the connection being the Levi-Civita one) and the gravitational degrees of freedom are encoded in not only the metric but also the connection $\mathrm{\Gamma }$, which is treated as an independent variable. We show that in this case the famous attractor behavior of simple nonminimally coupled models of inflation is lost. Therefore the attractors are not universal, but their existence depends on the underlying theory of gravity in a subtle way. We discuss what this means for chaotic models and their observational consequences.

We study the preheating and the in-process production of gravitational waves (GWs) after inflation in which the inflaton is nonminimally coupled to the curvature in a self-interacting quartic potential with the method of lattice simulation. We find that the nonminimal coupling enhances the amplitude of the density spectrum of inflaton quanta, and as a result, the peak value of the GW spectrum generated during preheating is enhanced as well and might reach the limit of detection in future GW experiments. The peaks of the GW spectrum not only exhibit distinctive characteristics as compared to those of minimally coupled inflaton potentials but also imprint information on the nonminimal coupling and the parametric resonance, and thus the detection of these peaks in the future will provide us a new avenue to reveal the physics of the early universe.

Primordial black holes can be produced by a long-range attractive fifth force stronger than gravity, mediated by a light scalar field interacting with nonrelativistic “heavy” particles. As soon as the energy fraction of heavy particles reaches a threshold, the fluctuations rapidly become nonlinear. The overdensities collapse into black holes or similar screened objects, without the need for any particular feature in the spectrum of primordial density fluctuations generated during inflation. We discuss whether such primordial black holes can constitute the total dark matter component in the Universe.

We show that the correct way to extract parton distribution functions from the reduced Ioffe-time distribution, a ratio of the Ioffe-time distribution for a moving hadron and a hadron at rest, is through a factorization formula. This factorization exists because, at small distances, forming the ratio does not change the infrared behavior of the numerator, which is factorizable. We illustrate the effect of such a factorization by applying it to results in the literature.

Using the Nambu–Jona-Lasinio model with the $U(2)\times U(2)$ chiral symmetric effective four-quark interactions, we derive the amplitude of the radiative decay $f_1(1285)\to {\pi }^{+}{\pi }^{-}\gamma$, find the decay width $\mathrm{\Gamma }(f_1\to {\pi }^{+}{\pi }^{-}\gamma )=346\mathrm{keV}$ and obtain the spectral dipion effective mass distribution. It is shown that in contrast to the majority of theoretical estimates (which consider the $a_1(1260)$ meson exchange as the dominant one), the most relevant contribution to this process is the ${\rho }^0$-resonance exchange related with the triangle $f_1{\rho }^0\gamma$ anomaly. The spectral function is obtained to be confronted with the future empirical data.