In this paper, we examine the interactions of top quarks with the $Z$ boson using the top quark pair production associated with the neutrino pair ($t\overline{t}{\nu }_l\overline{{\nu }_l}$) at the LHC. In particular, potential constraints on the anomalous electroweak top quark interactions are determined by considering two opposite-sign charged leptons, missing energy, and two b-tagged jets in the final state. The analysis is performed for a high luminosity scenario of the LHC with an integrated luminosity of $3{\mathrm{ab}}^{-1}$ of proton-proton collisions at a center-of-mass energy of 14 TeV. The 95% confidence intervals are computed on the anomalous couplings considering a realistic detector simulation of an upgraded CMS detector including an average of 200 proton-proton interactions per bunch crossing. We find that the $t\overline{t}{\nu }_l\overline{{\nu }_l}$ channel can provide stringent bounds on the relevant Wilson coefficients and has the potential to serve as an additional handle beside the $t\overline{t}Z(Z\to l^{+}{l}^{-})$ and other channels to search for new physics.

We measured the branching fractions of the decays ${\chi }_{cJ}\to {\mathrm{\Sigma }}^{-}{\overline{\mathrm{\Sigma }}}^{+}$ for the first time using the final states $n\overline{n}{\pi }^{+}{\pi }^{-}$. The data sample exploited here is $448.1\times {10}^6\psi (3686)$ events collected with BESIII. We find $\mathcal{B}({\chi }_{cJ}\to {\mathrm{\Sigma }}^{-}{\overline{\mathrm{\Sigma }}}^{+})=(51.3\pm 2.4\pm 4.1)\times {10}^{-5},(5.7\pm 1.4\pm 0.6)\times {10}^{-5}$, and $(4.4\pm 1.7\pm 0.5)\times {10}^{-5}$, for $J=0$, 1, 2, respectively, where the first uncertainties are statistical and the second systematic.

In this paper, we provide the representation of the symplectic group $Sp(2n,\mathbb{R})$ in polymer quantum mechanics. We derive the propagator of the polymer free particle and the polymer harmonic oscillator without considering a polymer scale. The polymer scale is then introduced to reconcile our results with those expressions for the polymer free particle. The propagator for the polymer harmonic oscillator implies nonunitary evolution.

The string breaking phenomenon in QCD can be studied using the gauge/string duality. In this approach, one can make estimates of some of the string breaking distances at nonzero temperature and baryon chemical potential. These point toward the enhancement of baryon production in strong decays of heavy mesons in a dense baryonic medium.

A nonlocal mass operator is consistently defined in the local form through the introduction of a set of additional fields with geometrical appropriated properties. A local and polynomial gauge-invariant action is thus established. Equations compatible with the study of renormalization, from the algebraic point of view, are presented in the Landau gauge.

We study the axial perturbations of spontaneously scalarized black holes in Einstein-Gauss-Bonnet theories. We consider the nodeless solutions of the fundamental branch of the model studied by Doneva and Yazadjiev” [Phys. Rev. Lett. 120, 131103 (2018)], which possesses a region of radially stable configurations, as shown by Blazquez-Salcedo et al. [Phys. Rev. D 98, 084011 (2018)]. Here we show that almost all of the radially stable black holes are also stable under axial perturbations. When the axial potential is no longer strictly positive, we make use of the S-deformation method to show stability. As for the radial perturbations, hyperbolicity is lost below a certain critical horizon size for a fixed coupling constant. In the stable region, we determine the spectrum of the quasinormal modes by time evolution and by solving the associated time-independent eigenvalue problem.

We evaluate QCD effects in the neutrinoless double beta ($0\nu \beta \beta$) decay, originating from a new physics short-range mechanism in the form of five dimension-9 operators. For this, we employ the one-loop and two-loop renormalization group equations for the corresponding Wilson coefficients, performing the RGE evolution from the new physics scales (estimated as $\mathrm{\Lambda }\sim {10}^2\mathrm{GeV}$) to the typical spacelike $0\nu \beta \beta$ scale $Q\sim 0.1\mathrm{GeV}$. Since the latter scale is clearly nonperturbative, we apply various IR-safe variants of QCD in which the running coupling has no Landau singularities at low spacelike $Q$. We point out that the correct treatment of the IR-safe analogs of the (noninteger) powers of the couplings is important. It turns out that in most cases of the considered operators the resulting QCD effects can be significant in this process, i.e., can be stronger than the effects of the present uncertainties in the nuclear matrix elements.

We introduced here the study of a QCD based on a complex group. Our aim is to show that a gauge theory with a complex symmetry develops some of the features required for the description of a confined phase. This theory leads to gluons with propagations characteristic of $i$ particles, fundamental constituents of propagators in the Gribov scenario, together with a gluon propagating with the mode predicted by ’t Hooft for the quark confinement. In this way, we present in this same theory a possible gluon condensate, together with a confining interquark potential after the coupling to fermions. This is a novelty, as, up to now, all theories of the Gribov-Zwanziger (GZ) kind do not generate quark confinement.

Families of $J^P={\frac{1}{2}}^{+}$ nucleons ($N(939)$, $N(1440)$, $N(1710)$, $N(1880)$, $N(2100)$, $N(2300)$) and $J^P={\frac{3}{2}}^{-}$ nucleons ($N(1520)$, $N(1700)$, $N(1875)$, and $N(2120)$) are scrutinized from the point of view of the configurational entropy (CE). The mass spectra of higher $J^P$ resonances in each one of these families are then obtained when configurational-entropic Regge trajectories, that relate the CE of nucleon families to both their $J^P$ spin and also to their experimental mass spectra, are interpolated. The mass spectra of the next generation of nucleon resonances are then compared to already established baryonic states in particle data group (PDG). Besides the zero temperature case, the finite temperature analysis is also implemented.

Chiral higher spin gravity is unique in being the smallest higher spin extension of gravity and in having a simple local action both in flat and (anti-)de Sitter spaces. It must be a closed subsector of any other higher spin theory in four dimensions, which makes it an important building block and benchmark. Using the flat space version for simplicity, we perform a thorough study of quantum corrections in chiral theory, which strengthens our earlier results [E. Skvortsov, T. Tran, and M. Tsulaia, Phys. Rev. Lett. 121, 031601 (2018)]. Even though the interactions are naively nonrenormalizable, we show that there are no UV divergences in two-, three-, and four-point amplitudes at one loop thanks to the higher spin symmetry. We also give arguments that the AdS chiral theory should exhibit similar properties. It is shown that chiral theory admits Yang-Mills gaugings with $U(N)$, $SO(N)$, and $USp(N)$ groups, which is reminiscent of the Chan-Paton symmetry in string theory.

We investigate the structure of the gravity-induced generalized uncertainty principle in three dimensions. The subtleties of lower-dimensional gravity, and its important differences concerning four and higher dimensions, are duly taken into account, by considering different possible candidates for the gravitational radius, $R_g$, that is the minimal length/maximal resolution of the quantum mechanical localization process. We find that the event horizon of the $M\ne 0$ Bañados-Teitelboim-Zanelli micro-black-hole furnishes the most consistent $R_g$. This allows us to obtain a suitable formula for the generalized uncertainty principle in three dimensions, and also to estimate the corrections induced by the latter on the Hawking temperature and Bekenstein entropy. We also point to the extremal $M=0$ case, and its natural unit of length introduced by the cosmological constant, $\ell =1/\sqrt{-\mathrm{\Lambda }}$, as a possible alternative to $R_g$, and present a condensed matter analog realization of this scenario.

The traditional $S$-matrix does not exist for theories with massless particles, such as quantum electrodynamics. The difficulty in isolating asymptotic states manifests itself as infrared divergences at each order in perturbation theory. Building on insights from the literature on coherent states and factorization, we construct an $S$-matrix that is free of singularities order-by-order in perturbation theory. Factorization guarantees that the asymptotic evolution in gauge theories is universal, i.e., independent of the hard process. Although the hard $S$-matrix element is computed between well-defined few particle Fock states, dressed/coherent states can be seen to form as intermediate states in the calculation of hard $S$-matrix elements. We present a framework for the perturbative calculation of hard $S$-matrix elements combining Lorentz-covariant Feynman rules for the dressed-state scattering with time-ordered perturbation theory for the asymptotic evolution. With hard cutoffs on the asymptotic Hamiltonian, the cancellation of divergences can be seen explicitly. In dimensional regularization, where the hard cutoffs are replaced by a renormalization scale, the contribution from the asymptotic evolution produces scaleless integrals that vanish. A number of illustrative examples are given in QED, QCD, and $\mathcal{N}=4$ super-Yang-Mills theory.

In light of the current (and future) gravitational wave detections, more sensitive tests of general relativity can be devised. Black hole spectroscopy has long been proposed as a way to test the no-hair theorem, that is, how closely an astrophysical black hole can be described by the Kerr geometry. We use numerical relativity simulations from the Simulating eXtreme Spacetimes project (SXS) to assess the detectability of one extra quasinormal mode in the ringdown of a binary black hole coalescence, with numbers $(\ell ,m,n)$ distinct from the fundamental quadrupolar mode (2,2,0). Our approach uses the information from the complex waveform as well as from the time derivative of the phase in two different prescriptions that allow us to estimate the point at which the ringdown is best described by a single mode or by a sum of two modes. By scaling all amplitudes to a fiducial time $t_{\mathrm{peak}}+10M$ ($t_{\mathrm{peak}}$ is the time of maximum waveform amplitude), our results for nonspinning binaries indicate that, for mass ratios of $1:1$ to approximately $5:1$, the first overtone (2,2,1) will always have a larger excitation amplitude than the fundamental modes of the other harmonics (2,1,0), (3,3,0), and (4,4,0), making it a more promising candidate for detection. Even though the (2,2,1) mode damps about 3 times faster than the fundamental higher harmonics and its frequency is very close to that of the (2,2,0) mode, its larger excitation amplitude still guarantees a more favorable scenario for detection, as we show in a preliminary Rayleigh $\mathrm{criterion}+\mathrm{Fisher}$ matrix mode resolvability analysis of a simulation with nonzero spin consistent with GW150914. In particular, for nonspinning equal-mass binaries, the ratio of the amplitude of the first overtone (2,2,1) to the fundamental mode (2,2,0) will be $\gtrsim 0.65$, whereas the corresponding ratio for the higher harmonics will be $\lesssim 0.05$. For nonspinning binaries with mass ratios larger than $5:1$, we find that the modes (2,2,1), (2,1,0), and (3,3,0) should have comparable amplitude ratios in the range 0.3–0.4. The expectation that the (2,2,1) mode should be more easily detectable than the (3,3,0) mode is confirmed with an extension of the mode resolvability analysis for nonspinning cases with larger mass ratios, keeping the mass of the final black hole compatible with GW150914.

We consider scalar-tensor gravity with nonminimal derivative coupling and Born-Infeld electromagnetic field which is minimally coupled to gravity. Since the cosmological constant is taken into account it allowed us not only to derive a static black hole with a spherical horizon but also to obtain topological solutions with nonspherical horizons. The obtained metrics are thoroughly analyzed, namely for different distances and types of topology of horizon. To investigate singularities of the metrics Kretschmann scalar is used and it is shown that the character of singularity depends on the type of topology of horizon and dimension of space. We also investigate black hole’s thermodynamics, namely we obtain and examine the black hole’s temperature. To derive the first law of black hole’s thermodynamics Wald’s approach is applied. Nonetheless this approach is well established, there is ambiguity in definition of black hole’s entropy which can be resolved just by virtue of some independent approach.

The deep learning method has developed very fast as a tool for data analysis in recent years. Moreover, as a technique, it is quite promising as a way to analyze gravitational-wave detection data. Multiple works in the literature have already used deep learning to process simulated gravitational-wave data. In this paper, we apply deep learning to LIGO data. In order to improve the weak signal recognition, we design a new structure of the convolutional neural network (CNN). The key feature of our new CNN structure is the sensing layer. This layer mimics matched filtering but is different from the usual matched-filtering technique. Usually, the matched-filtering technique uses a full template bank to match the data. However, our sensing layer only uses tens of waveforms. Our new convolutional neural network admits comparable accuracy and efficiency of signal recognition compared to other deep learning works published in the literature. Based on our new CNN, we can clearly recognize the 11 confirmed gravitational-wave events included in O1 and O2. In addition, we find about 2000 gravitational-wave triggers in O1 data.

We investigate how a static and neutral distribution of external matter distorts a five-dimensional static black ring. We obtain a general expression for the distorted metric in terms of the background metric functions and the distortion fields, and find a multipole expansion for the latter. We demonstrate that the gravitational field of these external sources can be adjusted to remove the conical singularity of the undistorted black ring solution. We analyze properties of the distorted black ring for the specific cases of dipole and quadrupole distortions.

The nonminimal coupling of the nonzero vacuum expectation value of the self-interacting antisymmetric Kalb-Ramond field with gravity leads to a power-law hairy black hole having a parameter $s$, which encompasses the Reissner-Nordstrom black hole ($s=1$). We obtain the axially symmetric counterpart of this hairy solution, namely, the rotating Kalb-Ramond black hole, which encompasses, as special cases, Kerr ($s=0$) and Kerr-Newman ($s=1$) black holes. Interestingly, for a set of parameters ($M$, $a$, and $\mathrm{\Gamma }$), there exists an extremal value of the Kalb-Ramond parameter ($s=s_e$), which corresponds to an extremal black hole with degenerate horizons, while for $s<s_e$, it describes a nonextremal black hole with Cauchy and event horizons, and no black hole for $s>s_e$. We find that the extremal value $s_e$ is also influenced by these parameters. The black hole shadow size decreases monotonically and the shape gets more distorted with an increasing $s$; in turn, shadows of rotating Kalb-Ramond black holes are smaller and more distorted than the corresponding Kerr black hole shadows. We investigate the effect of the Kalb-Ramond field on the rotating black hole spacetime geometry and analytically deduced corrections to the light deflection angle from the Kerr and Schwarzschild black hole values. The deflection angle for Sgr A* and the shadow caused by the supermassive black hole M87* are included and compared with analogous results of Kerr black holes. The inferred circularity deviation $\mathrm{\Delta }C\le 0.10$ for the M87* black hole merely constrains the Kalb-Ramond field parameter, whereas shadow angular diameter ${\theta }_d=42\pm 3\mu \mathrm{as}$, within the $1\sigma$ region, places bounds $\mathrm{\Gamma }\le 0.09205$ for $s=1$ and $\mathrm{\Gamma }\le 0.02178$ for $s=3$.

We investigate primordial magnetogenesis and the evolution of the electromagnetic field through a quantum bounce P. Peter, E. J. Pinho, and N. Pinto-Neto, Phys. Rev. D 75, 023516 (2007)., in a model that starts in the far past from a contracting phase where only dust is present and the electromagnetic field is in the adiabatic quantum vacuum state. By including a coupling between curvature and electromagnetism of the form $R{F}_{\mu \nu }{F}^{\mu \nu }$, we find acceptable magnetic field seeds within the current observational constraints at 1 Mpc, and that the magnetic power spectrum evolves as a power-law with spectral index $n_B=6$. It is also shown that the electromagnetic backreaction is not an issue in the model under scrutiny.

We study the implications of the recently proposed Trans-Planckian censorship conjecture (TCC) for early Universe cosmology and in particular inflationary cosmology. The TCC leads to the conclusion that if we want inflationary cosmology to provide a successful scenario for cosmological structure formation, the energy scale of inflation has to be lower than ${10}^9\mathrm{GeV}$. Demanding the correct amplitude of the cosmological perturbations then forces the generalized slow-roll parameter $\epsilon$ of the model to be very small ($<{10}^{-31}$). This leads to the prediction of a negligible amplitude of primordial gravitational waves. For slow-roll inflation models, it also leads to severe fine-tuning of initial conditions.