A search for production of the supersymmetric partners of the top quark, top squarks, is presented. The search is based on proton-proton collision events containing multiple jets, no leptons, and large transverse momentum imbalance. The data were collected with the CMS detector at the CERN LHC at a center-of-mass energy of 13 TeV, and correspond to an integrated luminosity of $137{\mathrm{fb}}^{-1}$. The targeted signal production scenarios are direct and gluino-mediated top squark production, including scenarios in which the top squark and neutralino masses are nearly degenerate. The search utilizes novel algorithms based on deep neural networks that identify hadronically decaying top quarks and $W$ bosons, which are expected in many of the targeted signal models. No statistically significant excess of events is observed relative to the expectation from the standard model, and limits on the top squark production cross section are obtained in the context of simplified supersymmetric models for various production and decay modes. Exclusion limits as high as 1310 GeV are established at the 95% confidence level on the mass of the top squark for direct top squark production models, and as high as 2260 GeV on the mass of the gluino for gluino-mediated top squark production models. These results represent a significant improvement over the results of previous searches for supersymmetry by CMS in the same final state.

We calculate quantum gravitational corrections to the entropy of black holes using the Wald entropy formula within an effective field theory approach to quantum gravity. The corrections to the entropy are calculated to second order in curvature and we calculate a subset of those at third order. We show that, at third order in curvature, interesting issues appear that had not been considered previously in the literature. The fact that the Schwarzschild metric receives corrections at this order in the curvature expansion has important implications for the entropy calculation. Indeed, the horizon radius and the temperature receive corrections. These corrections need to be carefully considered when calculating the Wald entropy.

We determine the effect on the computational complexity of a conformal anomaly using the $\mathrm{complexity}=\text{action}$ prescription of the gauge/gravity correspondence. To allow the involvement of said anomaly, we extend previous studies to include arbitrary values for the anisotropic parameter and the magnetic field, respectively, on the Mateos-Trancanelli and D’Hoker-Kraus holographic models. Our main result is that the rate of change of the computational complexity is independent of the conformal anomaly in both cases. In addition, this allows us to show that, if so desired, the saturation of Lloyd’s bound at infinite time can be used as a renormalization condition.

In Eddington gravity, the action principle involves only the symmetric parts of the connection and the Ricci tensor, with a metric that emerges proportionally to the latter. Here, we relax this symmetric character, prolong the action with the antisymmetric parts of the Ricci term, and allow for various couplings with scalar fields. We propose two possible invariant actions formed by distinct combinations of the independent Ricci tensors and show that the generated metric must involve an additional antisymmetric part due to the relaxation of the symmetrization property. The comprehensive study shows that the second curvature influences the dynamics of the connection, hence its solution in terms of the metric, and the evolution of the scalar fields. These new dynamical features are expected to stand viable and to have interesting implications in domains where scalar fields are indispensable.

We investigate a generalized form of the phenomenologically emergent dark energy model, known as generalized emergent dark energy (GEDE), introduced by Li and Shafieloo [Astrophys. J. 902, 58 (2020)] in light of a series of cosmological probes and considering the evolution of the model at the level of linear perturbations. This model introduces a free parameter $\mathrm{\Delta }$ that can discriminate between the $\mathrm{\Lambda }\mathrm{CDM}$ (corresponds to $\mathrm{\Delta }=0$) or the phenomenologically emergent dark energy (PEDE) (corresponds to $\mathrm{\Delta }=1$) models, allowing us to determine which model is preferred most by the fit of the observational datasets. We find evidence in favor of the GEDE model for Planck alone and in combination with R19, while the Bayesian model comparison is inconclusive when supernovae type Ia or baryon acoustic oscillation (BAO) data are included. In particular, we find that the $\mathrm{\Lambda }\mathrm{CDM}$ model is disfavored at more than $2\sigma$ C.L. for most of the observational datasets considered in this work and PEDE is in agreement with Planck $2018+\mathrm{BAO}+\mathrm{R}19$ combination within $1\sigma$ C.L.

Recent theoretical studies have suggested that the suddenly recoiled atom struck by dark matter (DM) particle is much more likely to excite or lose its electrons than expected. Such Migdal effect opens a new avenue for exploring the sub-GeV DM particles. There have been various attempts to describe the Migdal effect in liquid and semiconductor targets. In this paper we incorporate the treatment of the bremsstrahlung process and the electronic many-body effects to give a full description of the Migdal effect in bulk semiconductor targets diamond and silicon. Compared with the results obtained with the atom-centered localized Wannier functions (WFs) under the framework of the tight-binding (TB) approximation, the method proposed in this study yields much larger event rates in the low energy regime, due to a ${\omega }^{-4}$ scaling. We also find that the effect of the bremsstrahlung photon mediating the Coulomb interaction between recoiled ion and the electron-hole pair is equivalent to that of the exchange of a single phonon.

We compute trace anomaly contribution to hydrogen atom mass, which turns out to be related to the part of the Lamb shift. To the best of our knowledge, this is a first model independent calculation of trace anomaly contribution to a bound state. This finding might shed new light on our understandings of the mass structure of QCD bound states, such as, heavy quarkonium.

We study fully differential quarkonia photoproduction observables in ultraperipheral collisions as functions of momentum transfer squared. We employ the dipole picture of the QCD part of the scattering with proton and nucleus targets, with the projectile being a quasireal photon flux emitted by an incoming hadron. We analyze such observables for ground $J/\psi$, $\mathrm{\Upsilon }(1S)$ and excited ${\psi }^{\prime }$, $\mathrm{\Upsilon }(2S)$ states whose light-front wave functions are obtained in the framework of an interquark potential model incorporating the Melosh spin transformation. Two different low-$x$ saturation models, one obtained by solving the Balitsky-Kovchegov equation with the collinearly improved kernel and the other with a Gaussian impact-parameter-dependent profile, are used to estimate the underlined theoretical uncertainties of our calculations. The results for the proton target and with charmonium in the final state are in agreement with the available HERA data, while in the case of the nucleus target we make predictions for $\gamma A$ and $AA$ differential cross sections at different $W$ and at $\sqrt{s}=5.02\mathrm{TeV}$, respectively.

An action for the higher-derivative corrections to minimal gauged Euclidean supergravity in four dimensions has been recently proposed. We demonstrate that the supersymmetric solutions of this model are those of the two-derivative action, and investigate some of their properties. In particular, we prove a formula for the renormalized on-shell action in terms of contributions from fixed points of a $U(1)$ action, and confirm that it is invariant under deformations which preserve the boundary almost contact structure.

We discuss unpolarized neutrino- and anti-neutrino-nucleon deep inelastic scattering using a chiral doublet of baryonic sources with explicit symmetry breaking, in a slice of ${\mathrm{AdS}}_5$ with both a hard and soft wall. We explicitly derive the direct and transition form factors for the vector and axial-vector currents for the holographic dual of a proton and neutron. We use them to derive the $s$-channel structure functions for neutrino and antineutrino scattering on a proton and neutron in bulk. The $t$-channel contributions stemming from the Pomeron and Reggeon exchanges are also evaluated explicitly. The pertinent even and odd structure functions in the limit of large and small parton momentum fraction $x$ are given. The results allow for the extraction of the nonperturbative parton distribution functions carried by the sea and valence quarks both at large-$x$ and small-$x$ regimes. Our holographic parton distribution function (PDF) sets compare well with the Les Houches accord PDF (LHAPDF) and the coordinated theoretical-experiment project on QCD (CTEQ) PDF sets in the large-$x$ and small-$x$ regimes in the intermediate range of $Q^2<10{\mathrm{GeV}}^2$.

We compactify the ten-dimensional spacetime in heterotic supergravity leaving four-dimensional Minkowski spacetime. We search for nonsupersymmetric, non-Ricci-flat solutions of the equations of motion with the quadratic curvature term. By assuming that the extradimensional spaces are products of 2-manifolds, three types of solutions are found. They are $S^2\times T^2\times H^2/\mathrm{\Gamma }$, $S^2\times H^2/\mathrm{\Gamma }\times H^2/\mathrm{\Gamma }$, and $S^2\times S^2\times H^2/\mathrm{\Gamma }$, where $H^2/\mathrm{\Gamma }$ denotes a compact hyperbolic manifold. The metrics can be written explicitly, and they can be applied to phenomenology.

We study the modular symmetry on magnetized toroidal orbifolds with Scherk-Schwarz phases. In particular, we investigate finite modular flavor groups for three-generation modes on magnetized orbifolds. The three-generation modes can be the three-dimensional irreducible representations of covering groups and central extended groups of ${\mathrm{\Gamma }}_N$ for $N=3$, 4, 5, 7, 8, 16, that is, covering groups of $\mathrm{\Delta }(6(N/2{)}^2)$ for $N=\mathrm{even}$ and central extensions of $PSL(2,{\mathbb{Z}}_N)$ for $N=\mathrm{odd}$ with Scherk-Schwarz phases. We also study anomaly behaviors.

Using a new approach to the analysis of false vacuum decay based on the so-called tunneling potential, we develop a general method to find scalar potentials with a false vacuum with exactly solvable decay at the semiclassical level, including gravitational corrections. We examine in particular the decays of de Sitter vacua providing concrete examples that allow to explore analytically the transition between the Coleman-De Luccia and Hawking-Moss regimes.

An atom falling freely into a Kerr black hole in a Boulware-like vacuum is shown to emit radiation with a Planck spectrum at the Hawking temperature. For a cloud of falling atoms with random initial times, the radiation is thermal. The existence of this radiation is due to the acceleration of the vacuum field modes with respect to the falling atom. Its properties can be traced to the dominant role of conformal quantum mechanics in the neighborhood of the event horizon. We display this effect for a scalar field, though the acceleration radiation has a universal conformal behavior that is exhibited by all fields in the background of generic black holes.

Einstein equivalence principle (EEP), as one of the foundations of general relativity, is a fundamental test of gravity theories. In this paper, we propose a new method to test the EEP of electromagnetic interactions through observations of black hole photon rings, which naturally extends the scale of Newtonian and post-Newtonian gravity where the EEP violation through a variable fine structure constant has been well constrained to that of stronger gravity. We start from a general form of Lagrangian that violates EEP, where a specific EEP violation model could be regarded as one of the cases of this Lagrangian. Within the geometrical optical approximation, we find that the dispersion relation of photons is modified: for photons moving in circular orbit, the dispersion relation simplifies, and behaves such that photons with different linear polarizations perceive different gravitational potentials. This makes the size of black hole photon ring depend on polarization. Further assuming that the EEP violation is small, we derive an approximate analytic expression for spherical black holes showing that the change in size of the photon ring is proportional to the violation parameters. We also discuss several cases of this analytic expression for specific models. Finally, we explore the effects of black hole rotation and derive a modified proportionality relation between the change in size of photon ring and the violation parameters. The numerical and analytic results show that the influence of black hole rotation on the constraints of EEP violation is relatively weak for small magnitude of EEP violation and small rotation speed of black holes.

In Einstein-aether theory, we study the stability of black holes against odd-parity perturbations on a spherically symmetric and static background. For odd-parity modes, there are two dynamical degrees of freedom arising from the tensor gravitational sector and aether vector field. We derive general conditions under which neither ghosts nor Laplacian instabilities are present for these dynamical fields. We apply these results to concrete black hole solutions known in the literature and show that some of those solutions can be excluded by the violation of stability conditions. The exact Schwarzschild solution present for $c_{13}=c_{14}=0$, where $c_i$’s are the four coupling constants of the theory with $c_{ij}=c_i+c_j$, is prone to Laplacian instabilities along the angular direction throughout the horizon exterior. However, we find that the odd-parity instability of high radial and angular momentum modes is absent for black hole solutions with $c_{13}=c_4=0$ and $c_1\ge 0$.

There have been thousands of cosmological models for our early Universe proposed in the literature, and many of them claimed to be able to give rise to scale-invariant power spectrum as was favored by the observational data. It is thus interesting to think about whether there are some relations among them, e.g., the duality relation. In this paper, we investigate duality relations between cosmological models in framework of general relativity, not only with varying slow-roll parameter $\epsilon$ but also with sound speed $c_s$, which can then be understood as adiabatic duality. Several duality relationships are formulated analytically and verified numerically. We show that models with varying $\epsilon$ and constant $c_s$ can be dual in the scalar spectral index, but not the tensor one. On the other hand, allowing both $\epsilon$ and $c_s$ to vary can make models dual in both scalar and tensor spectral indices.

We identify potential sources of decoherence for $U(1)$ gauge bosons from a cosmological standpoint. Besides interactions with different species in the cosmological medium, we also consider effects due to the expansion of the Universe, which can produce particles (especially scalars) that can potentially interact with the photon in a quantum state. We look in particular at the case of axionlike particles and their predicted decay channels in our analysis. These interactions are shown to have a negligible effect as far as decoherence goes. Interaction rates with cosmic microwave background radiation or through Thomson scattering are small, so that the interstellar medium remains the biggest decoherence factor. Thus, quantum teleportation experiments with photon energies in the range 1–10 keV should be feasible at cosmological distances up to the galaxy formation epoch or beyond ($z\sim 100$).