One of the central goals of the newborn field of gravitational wave astronomy is to test gravity in the highly nonlinear, strong field regime characterizing the spacetime of black holes. In particular, “black hole spectroscopy” (the observation and identification of black hole quasinormal mode frequencies in the gravitational wave signal) is expected to become one of the main tools for probing the structure and dynamics of Kerr black holes. In this paper we take a significant step toward that goal by constructing a “post-Kerr” quasinormal mode formalism. The formalism incorporates a parametrized but general perturbative deviation from the Kerr metric and exploits the well-established connection between the properties of the spacetime’s circular null geodesics and the fundamental quasinormal mode to provide approximate, eikonal limit formulas for the modes’ complex frequencies. The resulting algebraic toolkit can be used in waveform templates for ringing black holes with the purpose of measuring deviations from the Kerr metric. As a first illustrative application of our framework, we consider the Johannsen-Psaltis deformed Kerr metric and compute the resulting deviation in the quasinormal mode frequency relative to the known Kerr result.

Nonlinearities in a realistic axion field potential may play an important role in the cosmological dynamics. In this paper we use the Boltzmann code class to solve the background and linear perturbations evolution of an axion field and contrast our results with those of CDM and the free axion case. We conclude that there is a slight delay in the onset of the axion field oscillations when nonlinearities in the axion potential are taken into account. Besides, we identify a tachyonic instability of linear modes resulting in the presence of a bump in the power spectrum at small scales. Some comments are in turn about the true source of the tachyonic instability, how the parameters of the axionlike potential can be constrained by Ly-$\alpha$ observations, and the consequences in the stability of self-gravitating objects made of axions.

The computation of observables in high-energy QCD involves an average over stochastic semiclassical small-$x$ gluon fields. The weight of various configurations is determined by the effective action. We introduce a method to study fluctuations of observables, functionals of the small-$x$ fields, which does not explicitly involve dipoles. We integrate out those fluctuations of the semiclassical gluon field under which a given observable is invariant. Thereby we obtain the effective potential for that observable describing its fluctuations about the average. We determine explicitly the effective potential for the covariant gauge gluon distribution both for the McLerran-Venugopalan (MV) model and for a (nonlocal) Gaussian approximation for the small-$x$ effective action. This provides insight into the correlation of fluctuations of the number of hard gluons versus their typical transverse momentum. We find that the spectral shape of the fluctuations of the gluon distribution is fundamentally different in the MV model, where there is a pileup of gluons near the saturation scale, versus the solution of the small-$x$ JIMWLK renormalization group, which generates essentially scale-invariant fluctuations above the absorptive boundary set by the saturation scale.

Recently, we introduced an approach for more easily interpreting searches for resonances at the LHC—and to aid in distinguishing between realistic and unrealistic alternatives for potential signals. This “simplified limits” approach was derived using the narrow width approximation (NWA)—and therefore was not obviously relevant in the case of wider resonances. Here, we broaden the scope of the analysis. First, we explicitly generalize the formalism to encompass resonances of finite width. We then examine how the width of the resonance modifies bounds on new resonances that are extracted from LHC searches. Second, we demonstrate, using a wide variety of cases, with different incoming partons, resonance properties, and decay signatures, that the limits derived in the NWA yield pertinant, and somewhat conservative (less stringent) bounds on the model parameters. We conclude that the original simplified limits approach is useful in the early stages of evaluating and interpreting new collider data and that the generalized approach is a valuable further aid when evidence points toward a broader resonance.

We study the phenomenology of two nonets of excited vector mesons, $\{\rho (1450),K^{*}(1410),\omega (1420),\varphi (1680)\}$ and $\{\rho (1700),K^{*}(1680),\omega (1650),\varphi (???)\}$, which (roughly) correspond to radially excited $2{{}^{3}S}_1$ and to orbitally excited $1{{}^{3}D}_1$ vector mesons. We evaluate the strong and radiative decays of these mesons into pseudoscalar and ground-state vector mesons by using an effective relativistic QFT model based on flavor symmetry. We compare decay widths and branching ratios with various experimental results listed in the PDG. An overall agreement of theory with experiment reinforces the standard quark-antiquark assignment of the resonances mentioned above. Predictions for not-yet-measured quantities are also made. In particular, we shall also make predictions for the not-yet-discovered $s\overline{s}$ state of the $1{{}^{3}D}_1$ nonet, denoted as $\varphi (???)$. Its mass can be estimated to be about 1930 MeV; hence we shall call this putative state $\varphi (1930)$. Its main decays are into $K{K}^{*}(892)$ (about 200 MeV) and $KK$ (about 100 MeV). Since this state couples also to $\gamma \eta$, it can be searched for in the near future in the photoproduction-based experiments GlueX and CLAS12 at Jefferson Lab.

The CIBER collaboration released their first observational data of the Cosmic IR background (CIB) radiation, which has significant excesses at around the wavelength $\sim 1\mu \mathrm{m}$ compared to theoretically-inferred values. The amount of the CIB radiation has a significant influence on the opaqueness of the Universe for TeV gamma-rays emitted from distant sources such as active galactic nuclei (AGNs). With the value of CIB radiation reported by the CIBER experiment, through the reaction of such TeV gamma-rays with the CIB photons, the TeV gamma-rays should be significantly attenuated during propagation, which would lead to energy spectra in disagreement with current observations of TeV gamma ray sources. In this article, we discuss a possible resolution of this tension between the TeV gamma-ray observations and the CIB data in terms of axion [or axion-like particles (ALPs)] that may increase the transparency of the Universe by the anomaly-induced photon-axion mixing. We find a region in the parameter space of the axion mass, $m_a\sim 7\times 10^{-10}–5\times 10^{-8}\mathrm{eV}$, and the axion-photon coupling constant, $1.5\times {10}^{-11}{\mathrm{GeV}}^{-1}\lesssim g_{a\gamma }\lesssim 8.8\times {10}^{-10}{\mathrm{GeV}}^{-1}$ that solves this problem.

We review lessons from the AdS/CFT correspondence that indicate that the emergence of locality in quantum gravity is contingent upon considering observables with a small number of insertions. Correlation functions, where the number of insertions scales with a power of the central charge of the CFT, are sensitive to nonlocal effects in the bulk theory, which arise from a combination of the effects of the bulk Gauss law and a breakdown of perturbation theory. To examine whether a similar effect occurs in flat space, we consider the scattering of massless particles in the bosonic string and the superstring in the limit, where the number of external particles, n, becomes very large. We use estimates of the volume of the Weil-Petersson moduli space of punctured Riemann surfaces to argue that string amplitudes grow factorially in this limit. We verify this factorial behavior through an extensive numerical analysis of string amplitudes at large n. Our numerical calculations rely on the observation that, in the large n limit, the string scattering amplitude localizes on the Gross-Mende saddle points, even though individual particle energies are small. This factorial growth implies the breakdown of string perturbation theory for $n\sim {(\frac{M_{\mathrm{pl}}}{E})}^{d-2}$ in $d$ dimensions, where $E$ is the typical individual particle energy. We explore the implications of this breakdown for the black hole information paradox. We show that the loss of locality suggested by this breakdown is precisely sufficient to resolve the cloning and strong subadditivity paradoxes.

The four-dimensional (4D) Lorentz group $SL(2,\mathbb{C})$ acts as the two-dimensional (2D) global conformal group on the celestial sphere at infinity where asymptotic 4D scattering states are specified. Consequent similarities of 4D flat space amplitudes and 2D correlators on the conformal sphere are obscured by the fact that the former are usually expressed in terms of asymptotic wave functions which transform simply under spacetime translations rather than the Lorentz $SL(2,\mathbb{C})$. In this paper we construct on-shell massive scalar wave functions in 4D Minkowski space that transform as $SL(2,\mathbb{C})$ conformal primaries. Scattering amplitudes of these wave functions are $SL(2,\mathbb{C})$ covariant by construction. For certain mass relations, we show explicitly that their three-point amplitude reduces to the known unique form of a 2D CFT primary three-point function and compute the coefficient. The computation proceeds naturally via Witten-like diagrams on a hyperbolic slicing of Minkowski space and has a holographic flavor.

We study spherically symmetric geometries made of anisotropic perfect fluid based on general relativity. The purpose of this work is to find and classify black hole solutions in closed spacetime. In a general setting, we find that a static and closed space exists only when the radial pressure is negative but its size is smaller than the density. The Einstein equation is eventually cast into a first-order autonomous equation on a two-dimensional plane of scale-invariant variables, which are equivalent to the Tolman-Oppenheimer-Volkoff equation in general relativity. Then, we display various solution curves numerically. An exact solution describing a black hole solution in a closed spacetime was known in [I. Cho and H. C. Kim, Phys. Rev. D 95, 084052 (2017)], which bears a naked singularity and negative-energy era. We find that these two deficits can be remedied when $\rho +3p_1>0$ and $\rho +p_1+2p_2<0$, where the second violates the strong energy condition.

In a recent work [Phys. Rev. D 94, 104010 (2016)], hereafter Paper I, we numerically studied different prescriptions for the dynamics of a spinning body in circular motion around a Schwarzschild black hole. In the present work, we continue this line of investigation by studying the rotating Kerr black hole. We consider the Mathisson-Papapetrou formalism under three different spin-supplementary conditions (SSC), the Tulczyjew SSC, the Pirani SSC, and the Ohashi-Kyrian-Semerak SSC, and analyze the different circular dynamics in terms of the innermost stable circular orbit (ISCO) shifts and the frequency parameter $x\equiv (M\mathrm{\Omega }{)}^{2/3}$, where $\mathrm{\Omega }$ is the orbital frequency and $M$ is the Kerr black hole mass. Then, we solve numerically the inhomogeneous $(2+1)D$ Teukolsky equation to contrast the asymptotic gravitational wave fluxes for the three cases. Our central observation made in Paper I for the Schwarzschild limit is found to hold true for the Kerr background; the three SSCs reduce to the same circular dynamics and the same radiation fluxes for small frequency parameters, but differences arise as $x$ grows close to the ISCO. For a positive Kerr parameter $a=0.9$, the energy fluxes mutually agree with each other within a 0.2% uncertainty up to $x<0.14$, while for $a=-0.9$, this level of agreement is preserved up to $x<0.1$. For large frequencies ($x\gtrsim 0.1$), however, the spin coupling of the Kerr black hole and the spinning body results in significant differences of the circular orbit parameters and the fluxes, especially for the $a=-0.9$ case. Instead, in the study of ISCO, the negative Kerr parameter $a=-0.9$ results in fewer discrepancies in comparison with the positive Kerr parameter $a=0.9$. As a side result, we mention that, apart from the Tulczyew SSC, ISCOs could not be found over the full range of spins; for $a=0.9$, for the Ohashi-Kyrian-Semerak SSC, ISCOs could be found only for $\sigma <0.25$ ($\sigma$ denotes the test body’s spin), while for the Pirani SSC, ISCOs could be found only for $-0.68<\sigma <0.64$. For $a=-0.9$, for the Ohashi-Kyrian-Semerak SSC, ISCOs could be found for $\sigma <0.721$.

It is shown that the addition of positive mass-squared terms to asymptotically safe gauge-Yukawa theories with perturbative UV fixed points leads to calculable radiative symmetry breaking in the IR. This phenomenon, and the multiplicative running of the operators that lies behind it, is akin to the radiative symmetry breaking that occurs in the supersymmetric standard model.

We extend the $D4-D8$ holographic construction to include three chiral and one heavy flavors, to describe heavy-light baryons with strangeness and their exotics. At strong coupling, the heavy meson always binds to the bulk instanton in the form of a flavor zero mode in the fundamental representation. We quantize the ensuing bound states using the collective quantization method, to obtain the spectra of heavy and strange baryons with both an explicit and hidden charm and bottom. Our results confirm the existence of two low-lying charmed pentaquark states with ${\frac{1}{2}}^{-},{\frac{3}{2}}^{-}$ assignments and predict many new ones with both a charm and bottom. They also suggest a quartet of low-lying neutral ${\mathrm{\Omega }}_c^0$ with assignments ${\frac{1}{2}}^{\pm },{\frac{3}{2}}^{\pm }$ that are heavier than the quintuplet of neutral ${\mathrm{\Omega }}_c^0$ recently reported by LHCb.

We evaluate the impact of sterile neutrino oscillations in the so-called $3+1$ scenario on the proposed long baseline experiment in USA and Japan. There are two proposals for the Japan experiment which are called T2HK and T2HKK. We show the impact of sterile neutrino oscillation parameters on the expected sensitivity of T2HK and T2HKK to mass hierarchy, $CP$ violation and octant of ${\theta }_{23}$ and compare it against that expected in the case of standard oscillations. We add the expected ten years data from DUNE and present the combined expected sensitivity of $\mathrm{T}2\mathrm{HKK}+\mathrm{DUNE}$ to the oscillation parameters. We do a full marginalization over the relevant parameter space and show the effect of the magnitude of the true sterile mixing angles on the physics reach of these experiments. We show that if one assumes that the source of $CP$ violation is the standard $CP$ phase alone in the test case, then it appears that the expected $CP$ violation sensitivity decreases due to sterile neutrinos. However, if we give up this assumption, then the $CP$ sensitivity could go in either direction. The impact on expected octant of ${\theta }_{23}$ and mass hierarchy sensitivity is shown to depend on the magnitude of the sterile mixing angles in a nontrivial way.

We present results for the isospin-0 $\pi \pi$ s-wave scattering length calculated with Osterwalder-Seiler valence quarks on Wilson twisted mass gauge configurations. We use three $N_f=2$ ensembles with unitary (valence) pion mass at its physical value (250 MeV), at 240 MeV (320 MeV) and at 330 MeV (400 MeV), respectively. By using the stochastic Laplacian Heaviside quark smearing method, all quark propagation diagrams contributing to the isospin-0 $\pi \pi$ correlation function are computed with sufficient precision. The chiral extrapolation is performed to obtain the scattering length at the physical pion mass. Our result $M_{\pi }{a}_0^{\mathrm{I}=0}=0.198(9)(6)$ agrees reasonably well with various experimental measurements and theoretical predictions. Since we only use one lattice spacing, certain systematics uncertainties, especially those arising from unitary breaking, are not controlled in our result.

We study hadronic transitions between bottomonium states using $496{\mathrm{fb}}^{-1}$ data collected at the $\mathrm{\Upsilon }(4S)$ resonance with the Belle detector at the KEKB asymmetric energy $e^{+}{e}^{-}$ collider. We measure $\mathcal{B}(\mathrm{\Upsilon }(4S)\to {\pi }^{+}{\pi }^{-}\mathrm{\Upsilon }(1S))=(8.2\pm 0.5(\text{stat})\pm 0.4(\text{syst}))\times {10}^{-5}$, $\mathcal{B}(\mathrm{\Upsilon }(4S)\to {\pi }^{+}{\pi }^{-}\mathrm{\Upsilon }(2S))=(7.9\pm 1.0(\text{stat})\pm 0.4(\text{syst}))\times {10}^{-5}$, and $\mathcal{B}(\mathrm{\Upsilon }(4S)\to \eta \mathrm{\Upsilon }(1S))=(1.70\pm 0.23(\text{stat})\pm 0.08(\text{syst}))\times {10}^{-4}$. We measure the ratio of branching fractions $\mathcal{R}=\mathcal{B}(\mathrm{\Upsilon }(4S)\to \eta \mathrm{\Upsilon }(1S))/\mathcal{B}(\mathrm{\Upsilon }(4S)\to {\pi }^{+}{\pi }^{-}\mathrm{\Upsilon }(1S))=2.07\pm 0.30(\text{stat})\pm 0.11(\text{syst})$. We search for the decay $\mathrm{\Upsilon }(1{{}^{3}D}_{1,2})\to \eta \mathrm{\Upsilon }(1S)$, but do not find significant evidence for such a transition. We also measure the initial-state radiation production cross sections of the $\mathrm{\Upsilon }(2S,3S)$ resonances and we find values compatible with the expected ones. Finally, the analysis of the $\mathrm{\Upsilon }(4S)\to {\pi }^{+}{\pi }^{-}\mathrm{\Upsilon }(1S)$ events shows indications for a resonant contribution due to the $f_0(980)$ meson.

Dijet events are studied in the proton-proton collision data set recorded at $\sqrt{s}=13\mathrm{TeV}$ with the ATLAS detector at the Large Hadron Collider in 2015 and 2016, corresponding to integrated luminosities of $3.5{\mathrm{fb}}^{-1}$ and $33.5{\mathrm{fb}}^{-1}$ respectively. Invariant mass and angular distributions are compared to background predictions and no significant deviation is observed. For resonance searches, a new method for fitting the background component of the invariant mass distribution is employed. The data set is then used to set upper limits at a 95% confidence level on a range of new physics scenarios. Excited quarks with masses below 6.0 TeV are excluded, and limits are set on quantum black holes, heavy $W^{\prime }$ bosons, $W^{*}$ bosons, and a range of masses and couplings in a $Z^{\prime }$ dark matter mediator model. Model-independent limits on signals with a Gaussian shape are also set, using a new approach allowing factorization of physics and detector effects. From the angular distributions, a scale of new physics in contact interaction models is excluded for scenarios with either constructive or destructive interference. These results represent a substantial improvement over those obtained previously with lower integrated luminosity.

Circularly polarized photons have the Berry curvature in the semiclassical regime. Based on the kinetic equation for such chiral photons, we derive the (non)equilibrium expression of the photon current in the direction of the vorticity. We briefly discuss the relevance of this “photonic chiral vortical effect” in pulsars and rotating massive stars and its possible realization in semiconductors.

We construct the gravitational solution of the Witten-Sakai-Sugimoto model by introducing a magnetic field on the flavor brane. Taking into account their backreaction, we re-solve type IIA supergravity in the presence of a magnetic field. Our calculation shows that the gravitational solutions are magnetically dependent and analytic both in the bubble (confined) and black brane (deconfined) case. We study the dual field theory at the leading order in the ratio of the number of flavors and colors, and also in the Veneziano limit. Some physical properties related to the hadronic physics in an external magnetic field are discussed by using our confined backreaction solution holographically. We also investigate the thermodynamics and holographic renormalization of this model in both phases by our solution. Since the backreaction of the magnetic field is considered in our gravitational solution, it allows us to study the Hawking-Page transition with flavors and colors of this model in the presence of the magnetic field. Finally we therefore obtain the holographic phase diagram with the contributions from the flavors and the magnetic field. Our holographic phase diagram is in qualitative agreement with the lattice QCD result, which thus can be interpreted as the inhibition of confinement or chirally broken symmetry by the magnetic field.