We consider deep inelastic scattering thought experiments in unitary conformal field theories. We explore the implications of the standard dispersion relations for the operator product expansion data. We derive positivity constraints on the operator product expansion coefficients of minimal-twist operators of even spin $s\ge 2$. In the case of $s=2$, when the leading-twist operator is the stress tensor, we reproduce the Hofman-Maldacena bounds. For $s>2$, the bounds are new.

We study the scalar-tensor theory of gravity profoundly in the action level as well as in the thermodynamic level. Contrary to the usual description in the literature about the equivalence in the two conformally connected frames, this paper addresses several incomplete inferences regarding it and mentions some inequivalences which were not pointed out earlier. In the thermodynamic level, our analysis shows the two frames are equivalent. In that process, we identify the entropy, the energy and the temperature for the thermodynamic description, and we find these quantities are conformally invariant even without any prior assumption. The same conclusion is reached from the gravitational action as well as from the Gibbons-Hawking-York boundary term, establishing the result in a more convincing manner.

We investigate the three-body system of $\pi \overline{K}{K}^{*}$ by using the fixed-center approximation to the Faddeev equation, taking the interaction between $\pi$ and $\overline{K}$, $\pi$ and $K^{*}$, and $\overline{K}$ and $K^{*}$ from the chiral unitary approach. The study is made assuming scattering of a $\pi$ on a $\overline{K}{K}^{*}$ cluster, which is known to generate the $f_1(1285)$ state. The resonant structure around 1650 MeV shows up in the modulus squared of the $\pi \text{−}(\overline{K}{K}^{*}{)}_{f_1(1285)}$ scattering amplitude and suggests that a $\pi \text{−}(\overline{K}{K}^{*}{)}_{f_1(1285)}$ state, with “exotic” quantum numbers $J^{PC}=1^{-+}$, can be formed. This state can be identified as the observed ${\pi }_1(1600)$ resonance. We suggest that this is the origin of the present ${\pi }_1(1600)$ resonance and propose to look at the $\pi f_1(1285)$ mode in future experiments to clarify the issue.

The masses of the charged fermion and the mixing angles among quarks are observed to be strongly hierarchical, while analogous parameters in the neutrino sector appear to be structureless or anarchical. We develop a class of unified models based on $SU(5)$ symmetry that explains these differing features probabilistically. With the aid of three input parameters that are hierarchical, and with the assumption that all the Yukawa couplings are uncorrelated random variables described by Gaussian distributions, we show by Monte Carlo simulations that the observed features of the entire fermion spectrum can be nicely reproduced. We extend our analysis to an $SU(5)$-based flavor $U(1)$ model making use of the Froggatt-Nielsen mechanism where the order one Yukawa couplings are modeled as random variables, which also shows good agreement with observations.

The present study is devoted for an improved analysis of the self-interference contribution of the electromagnetic dipole operator ${\mathcal{O}}_7$ to the double differential decay width $d\mathrm{\Gamma }/(d{s}_{1}d{s}_2)$ for the inclusive $\overline{B}\to X_s\gamma \gamma$ process, where the kinematical variables $s_1$ and $s_2$ are defined as $s_i=(p_b-q_i{)}^2/m_b^2$ with $p_b$, $q_1$, $q_2$ being the momenta of the $b$-quark and two photons. This calculation completes the next-to-leading-logarithmic (NLL) QCD prediction of the numerically important self-interference contribution of ${\mathcal{O}}_7$ by keeping the full dependence on the strange-quark mass $m_s$, which is introduced to control possible collinear configurations of one of the photons with the strange quark. Our results are given for exact $m_s$, in contrast to an earlier work where only logarithmic and constant terms in $m_s$ were retained. This improved NLL result for the $({\mathcal{O}}_7,{\mathcal{O}}_7)$-interference contribution shows that finite $m_s$ effects are only sizable near the kinematical endpoints of the spectrum $d\mathrm{\Gamma }/(d{s}_{1}d{s}_2)$. At the level of the branching ratio, in the phase-space region considered in this paper, it is observed that $\text{Br}[\overline{\mathrm{B}}\to {\mathrm{X}}_{\mathrm{s}}\gamma \gamma ]$ does not develop a sizable $m_s$ dependence: the impact on this branching ratio is less than 5% when $m_s$ is varied between 400–600 MeV. For the same phase-space region finite strange quark mass effects for the branching ratio are less than 7%.

We consider deformations of a conformal field theory that explicitly break some global symmetries of the theory. If the deformed theory is still a conformal field theory, one can exploit the constraints put by conformal symmetry to compute broken currents anomalous dimensions. We consider several instances of this scenario, using field theory techniques and also holographic ones, where necessary. Field theoretical methods suffice to discuss examples of symmetry-breaking deformations of the $O(N)$ model in $d=4-\epsilon$ dimensions. Holography is instrumental, instead, for computing current anomalous dimensions in $\beta$-deformed superconformal field theories and in a class of supersymmetric renormalization group flows at large $N$.

A physically plausible Lemaître-Tolman-Bondi collapse in the marginally bound case is considered. By “physically plausible,” we mean that the corresponding metric is ${\mathcal{C}}^1$ matched at the collapsing star surface and further that its intrinsic energy is, as due, stationary and finite. It is proved for this Lemaître-Tolman-Bondi collapse, for some parameter values, that its intrinsic central singularity is globally naked, thus violating the cosmic censorship conjecture with, for each direction, one photon, or perhaps a pencil of photons, leaving the singularity and reaching the null infinity. Our result is discussed in relation to some other cases in the current literature on the subject in which some of the central singularities are globally naked, too.

Numerical relativity is an essential tool in studying the coalescence of binary black holes (BBHs). It is still computationally prohibitive to cover the BBH parameter space exhaustively, making phenomenological fitting formulas for BBH waveforms and final-state properties important for practical applications. We describe a general hierarchical bottom-up fitting methodology to design and calibrate fits to numerical relativity simulations for the three-dimensional parameter space of quasicircular nonprecessing merging BBHs, spanned by mass ratio and by the individual spin components orthogonal to the orbital plane. Particular attention is paid to incorporating the extreme-mass-ratio limit and to the subdominant unequal-spin effects. As an illustration of the method, we provide two applications, to the final spin and final mass (or equivalently: radiated energy) of the remnant black hole. Fitting to 427 numerical relativity simulations, we obtain results broadly consistent with previously published fits, but improving in overall accuracy and particularly in the approach to extremal limits and for unequal-spin configurations. We also discuss the importance of data quality studies when combining simulations from diverse sources, how detailed error budgets will be necessary for further improvements of these already highly accurate fits, and how this first detailed study of unequal-spin effects helps in choosing the most informative parameters for future numerical relativity runs.

We consider different spin supplementary conditions (SSC) for a spinning compact binary with the leading-order spin-orbit (SO) interaction. The Lagrangian of the binary system can be constructed, but it is acceleration-dependent in two cases of SSC. We rewrite the generalized Hamiltonian formalism proposed by Ostrogradsky and compute the conserved quantities and the dissipative part of relative motion during the gravitational radiation of each SSC. We give the orbital elements and observed quantities of the SO dynamics, for instance, the energy and the orbital angular momentum losses and waveforms, and discuss their SSC dependence.

We study the cosmological evolution of a complex scalar field with a self-interaction potential $V(|\phi {|}^2)$, possibly describing self-gravitating Bose-Einstein condensates, using a fully general relativistic treatment. We generalize the hydrodynamic representation of the Klein-Gordon-Einstein equations in the weak field approximation developed in our previous paper [A. Suárez and P.-H. Chavanis, Phys. Rev. D 92, 023510 (2015)]. We establish the general equations governing the evolution of a spatially homogeneous complex scalar field in an expanding background. We show how they can be simplified in the fast oscillation regime (equivalent to the Thomas-Fermi, or semiclassical, approximation) and derive the equation of state of the scalar field in parametric form for an arbitrary potential $V(|\phi {|}^2)$. We explicitly consider the case of a quartic potential with repulsive or attractive self-interaction. For repulsive self-interaction, the scalar field undergoes a stiff matter era followed by a pressureless dark matter era in the weakly self-interacting regime and a stiff matter era followed by a radiationlike era and a pressureless dark matter era in the strongly self-interacting regime. For attractive self-interaction, the scalar field undergoes an inflation era followed by a stiff matter era and a pressureless dark matter era in the weakly self-interacting regime and an inflation era followed by a cosmic stringlike era and a pressureless dark matter era in the strongly self-interacting regime (the inflation era is suggested, not demonstrated). We also find a peculiar branch on which the scalar field emerges suddenly at a nonzero scale factor with a finite energy density. At early times, it behaves as a gas of cosmic strings. At later times, it behaves as dark energy with an almost constant energy density giving rise to a de Sitter evolution. This is due to spintessence. We derive the effective cosmological constant produced by the scalar field. Throughout the paper, we analytically characterize the transition scales of the scalar field and establish the domain of validity of the fast oscillation regime. We analytically confirm and complement the important results of Li, Rindler-Daller, and Shapiro [Phys. Rev. D 89, 083536 (2014)]. We determine the phase diagram of a scalar field with repulsive or attractive self-interaction. We show that the transition between the weakly self-interacting regime and the strongly self-interacting regime depends on how the scattering length of the bosons compares with their effective Schwarzschild radius. We also constrain the parameters of the scalar field from astrophysical and cosmological observations. Numerical applications are made for ultralight bosons without self-interaction (fuzzy dark matter), for bosons with repulsive self-interaction, and for bosons with attractive self-interaction (QCD axions and ultralight axions).

We study three possible ways to circumvent the sign problem in the O(3) nonlinear sigma model in $1+1$ dimensions. We compare the results of the worm algorithm to complex Langevin and multiparameter reweighting. Using the worm algorithm, the thermodynamics of the model is investigated, and continuum results are shown for the pressure at different $\mu /T$ values in the range 0–4. By performing $T=0$ simulations using the worm algorithm, the Silver Blaze phenomenon is reproduced. Regarding the complex Langevin, we test various implementations of discretizing the complex Langevin equation. We found that the exponentialized Euler discretization of the Langevin equation gives wrong results for the action and the density at low $T/m$. By performing a continuum extrapolation, we found that this discrepancy does not disappear and depends slightly on temperature. The discretization with spherical coordinates performs similarly at low $\mu /T$ but breaks down also at some higher temperatures at high $\mu /T$. However, a third discretization that uses a constraining force to achieve the ${\varphi }^2=1$ condition gives correct results for the action but wrong results for the density at low $\mu /T$.

In this paper, we update the predictions for exclusive $J/\mathrm{\Psi }$, $\mathrm{\Psi }(2S)$, and $\mathrm{\Upsilon }$ photoproduction in proton-proton and nucleus-nucleus collisions at the Run 2 LHC energies obtained with the color dipole formalism and considering the impact-parameter color glass condensate model (bCGC) for the forward dipole-target scattering amplitude. The impact of the charm mass on the predictions is investigated, and a comparison with the LHCb data on rapidity distributions and photon-hadron cross sections is presented. Our results demonstrate that the current data can be quite well described by the bCGC model, which takes into account nonlinear effects in the QCD dynamics and reproduces the very precise HERA data, without introducing any additional effect or free parameter.

Yang-Mills (YM) theory and QCD are known to be renormalizable, but not ultraviolet (UV) finite, order by order, in perturbation theory. It is a fundamental question whether YM theory or QCD is UV finite, or only renormalizable, order by order, in the large-$N$ ’t Hooft or Veneziano expansions. We demonstrate that the renormalization group (RG) and asymptotic freedom imply that in ’t Hooft large-$N$ expansion the $S$ matrix in YM theory is UV finite, while in both ’t Hooft and Veneziano large-$N$ expansions, the $S$ matrix in confining massless QCD is renormalizable but not UV finite. By the same argument, the large-$N$ $\mathcal{N}=1$ supersymmetry (SUSY) YM $S$ matrix is UV finite as well. Besides, we demonstrate that, in both ’t Hooft and Veneziano large-$N$ expansions, the correlators of local gauge-invariant operators, as opposed to the $S$ matrix, are renormalizable but, in general, not UV finite, either in YM theory and $\mathcal{N}=1$ SUSY YM theory or a fortiori in massless QCD. Moreover, we compute explicitly the counterterms that arise from renormalizing the ’t Hooft and Veneziano expansions by deriving in confining massless QCD-like theories a low-energy theorem of the Novikov-Shifman-Vainshtein-Zakharov type that relates the log derivative with respect to the gauge coupling of a $k$-point correlator, or the log derivative with respect to the RG-invariant scale, to a ($k+1$)-point correlator with the insertion of $\mathrm{Tr}{F}^2$ at zero momentum. Finally, we argue that similar results hold in the large-$N$ limit of a vast class of confining massive QCD-like theories, provided a renormalization scheme exists—as, for example, $\overline{\mathrm{MS}}$—in which the beta function is not dependent on the masses. Specifically, in both ’t Hooft and Veneziano large-$N$ expansions, the $S$ matrix in confining massive QCD and massive $\mathcal{N}=1$ SUSY QCD is renormalizable but not UV finite.

The crucial parameter in the current Monte Carlo models of high energy hadron-hadron interaction is the transverse momentum cutoff $p_{T0}$ for parton-parton interactions, which slowly grows with energy and regularizes the cross section. This modification of the collinear factorization formula goes beyond the leading power, and thus a natural question arises if such a cutoff can be extracted from a formalism that takes into account power corrections. In this work, we consider the high energy factorization (HEF) valid at small $x$ and a new model, based on a similar principle to HEF, which in addition has a limit respecting the Dokshitzer-Dyakonov-Troyan formula for the dijet momentum disbalance spectrum. The minijet cross section and its suppression are then analyzed in two ways. First, we study minijets directly in the low-$p_T$ region and demonstrate that higher twist corrections do generate suppression of the inclusive jet production cross section though these effects are not leading to the increase of the cutoff with incident energy. Second, we consider hard inclusive dijet production where multiparton interactions (MPIs) with minijets produce power corrections. We introduce an observable constructed from the differential cross section in the ratio $\tau$ of dijet disbalance to the average dijet $p_T$ and demonstrate that the $\tau >1$ region is sensitive to the cutoff $p_{T0}$ in the MPI minijet models. The energy dependence of the cutoff is reflected in the energy dependence of the bimodality coefficient $b$ of the $\tau$ distribution. We compare $b$ calculated from pythia, where one can conveniently control MPIs by the program parameters, and HEF for a few unintegrated gluon distributions (UGDs). We find that the energy dependence of $b$ is very sensitive to the particular choice of UGD and in some models it resembles predictions of the Monte Carlo models.

Using $1310.6\times 10^{6}J/\psi$ and $447.9\times 10^6\psi (3686)$ events collected with the BESIII detector at the BEPCII $e^{+}{e}^{-}$ collider, the branching fractions and the angular distributions of $J/\psi$ and $\psi (3686)$ decays to $\mathrm{\Lambda }\overline{\mathrm{\Lambda }}$ and ${\mathrm{\Sigma }}^0{\overline{\mathrm{\Sigma }}}^0$ final states are measured. The branching fractions are determined, with much improved precision, to be $19.43\pm 0.03\pm 0.33$, $11.64\pm 0.04\pm 0.23$, $3.97\pm 0.02\pm 0.12$ and $2.44\pm 0.03\pm 0.11$ for $J/\psi \to \mathrm{\Lambda }\overline{\mathrm{\Lambda }}$, $J/\psi \to {\mathrm{\Sigma }}^0{\overline{\mathrm{\Sigma }}}^0$, $\psi (3686)\to \mathrm{\Lambda }\overline{\mathrm{\Lambda }}$ and $\psi (3686)\to {\mathrm{\Sigma }}^0{\overline{\mathrm{\Sigma }}}^0$, respectively. The polar angular distributions of $\psi (3686)$ decays are measured for the first time, while those of $J/\psi$ decays are measured with much improved precision. In addition, the ratios of branching fractions $\frac{\mathcal{B}(\psi (3686)\to \mathrm{\Lambda }\overline{\mathrm{\Lambda }})}{\mathcal{B}(J/\psi \to \mathrm{\Lambda }\overline{\mathrm{\Lambda }})}$ and $\frac{\mathcal{B}(\psi (3686)\to {\mathrm{\Sigma }}^0{\overline{\mathrm{\Sigma }}}^0)}{\mathcal{B}(J/\psi \to {\mathrm{\Sigma }}^0{\overline{\mathrm{\Sigma }}}^0)}$ are determined to test the “12% rule.”

Euclidean field theories admit more general deformations than usually discussed in quantum field theories because of mixing between rotational symmetry and internal symmetry (also known as topological twist). Such deformations may be relevant, and if the subsequent renormalization group flow leads to a nontrivial fixed point, it generically gives rise to a scale invariant Euclidean field theory without conformal invariance. Motivated by an ansatz studied in cosmological models some time ago, we develop a holographic dual description of such renormalization group flows in the context of $\mathrm{AdS}/\mathrm{CFT}$. We argue that the nontrivial fixed points require fine-tuning of the bulk theory, in general, but remarkably we find that the $O(3)$ Yang-Mills theory coupled with the four-dimensional Einstein gravity in the minimal manner supports such a background with the Euclidean anti–de Sitter metric.

We discuss the computation of holographic entanglement entropy for interface conformal field theories. The fact that globally well-defined Fefferman-Graham coordinates are difficult to construct makes the regularization of the holographic theory challenging. We introduce a simple new cutoff procedure, which we call “double cutoff” regularization. We test the new cutoff procedure by comparing the results for holographic entanglement entropies using other cutoff procedures and find agreement. We also study three dimensional conformal field theories with a two dimensional interface. In that case the dual bulk geometry is constructed using warped geometry with an ${\mathrm{AdS}}_3$ factor. We define an effective central charge to the interface through the Brown-Henneaux formula for the ${\mathrm{AdS}}_3$ factor. We investigate two concrete examples, showing that the same effective central charge appears in the computation of entanglement entropy and governs the conformal anomaly.

We study the properties of compact stars in the Randall-Sundrum type-II braneworld (BW) model. To this end, we solve the braneworld generalization of the stellar structure equations for a static fluid distribution with spherical symmetry considering that the spacetime outside the star is described by a Schwarzschild metric. First, the stellar structure equations are integrated employing the so-called causal limit equation of state (EOS), which is constructed using a well-established EOS at densities below a fiducial density, and the causal EOS $P=\rho$ above it. It is a standard procedure in general relativistic stellar structure calculations to use such EOSs for obtaining a limit in the mass radius diagram, known as the causal limit, above which no stellar configurations are possible if the EOS fulfills the condition that the sound velocity is smaller than the speed of light. We find that the equilibrium solutions in the braneworld model can violate the general relativistic causal limit, and for sufficiently large mass they approach asymptotically to the Schwarzschild limit $M=2R$. Then, we investigate the properties of hadronic and strange quark stars using two typical EOSs: a nonlinear relativistic mean-field model for hadronic matter and the Massachusetts Institute of Technology (MIT) bag model for quark matter. For masses below $\sim 1.5M_{\odot }–2M_{\odot }$, the mass versus radius curves show the typical behavior found within the frame of general relativity. However, we also find a new branch of stellar configurations that can violate the general relativistic causal limit and that, in principle, may have an arbitrarily large mass. The stars belonging to this new branch are supported against collapse by the nonlocal effects of the bulk on the brane. We also show that these stars are always stable under small radial perturbations. These results support the idea that traces of extra dimensions might be found in astrophysics, specifically through the analysis of masses and radii of compact objects.

We present an asymptotically flat and stationary multiblack lens solution with biaxisymmetry of $U(1)\times U(1)$ as a supersymmetric solution in the five-dimensional minimal ungauged supergravity. We show that the spatial cross section of each degenerate Killing horizon admits different lens space topologies of $L(n,1)=S^3/{\mathbb{Z}}_n$ as well as a sphere $S^3$. Moreover, we show that, in contrast to the higher-dimensional Majumdar-Papapetrou multiblack hole and multi-Breckenridge-Myers-Peet-Vafa (BMPV) black hole spacetime, the metric is smooth on each horizon even if the horizon topology is spherical.