In this work, we systematically study the two-body strong decay of the $\rho /{\rho }_3$ states, which are observed and grouped into the $\rho /{\rho }_3$ meson family. By performing the phenomenological analysis, the underlying properties of these states are obtained and tested. What is more important is that abundant information of their two-body strong decays is predicted, which will be helpful to further and experimentally study these states.

We use matrix models to characterize deconfinement at a nonzero temperature $T$ for an $SU(2)$ gauge theory in three spacetime dimensions. At one-loop order, the potential for a constant vector potential $A_0$ is $\sim T^3$ times a trilogarithm function of $A_0/T$. In addition, we add various nonperturbative terms to model deconfinement. The parameters of the model are adjusted by fitting the lattice results for the pressure. The nonperturbative terms are dominated by a constant term $\sim T^2{T}_d$, where $T_d$ is the temperature for deconfinement. Besides this constant, we add terms which are nontrivial functions of $A_0/T$, both $\sim T^2{T}_d$ and $\sim T{T}_d^2$. There is only a mild sensitivity to the details of these nonconstant terms. Overall we find a good agreement with the lattice results. For the pressure, the conformal anomaly, and the Polyakov loop the nonconstant terms are relevant only in a narrow region below $\sim 1.2T_d$. We also compute the ’t Hooft loop, and find that the details of the nonconstant terms enter in a much wider region, up to $\sim 4T_d$.

The measurement of charged-particle event shape variables is presented in inclusive inelastic $pp$ collisions at a center-of-mass energy of 7 TeV using the ATLAS detector at the LHC. The observables studied are the transverse thrust, thrust minor, and transverse sphericity, each defined using the final-state charged particles’ momentum components perpendicular to the beam direction. Events with at least six charged particles are selected by a minimum-bias trigger. In addition to the differential distributions, the evolution of each event shape variable as a function of the leading charged-particle transverse momentum, charged-particle multiplicity, and summed transverse momentum is presented. Predictions from several Monte Carlo models show significant deviations from data.

We search for the decay $\mathit{{\rm Y}}(1S)\to \gamma A^0$, $A^0\to gg$ or $\mathrm{s}\overline{\mathrm{s}}$, where $A^0$ is the pseudoscalar light Higgs boson predicted by the next-to-minimal supersymmetric Standard Model. We use a sample of $(17.6\pm 0.3)\times {10}^6$ $\mathit{{\rm Y}}(1S)$ mesons produced in the BABAR experiment via $e^{+}{e}^{-}\to \mathit{{\rm Y}}(2S)\to {\pi }^{+}{\pi }^{-}\mathit{{\rm Y}}(1S)$. We see no significant signal and set 90%-confidence-level upper limits on the product branching fraction $\mathcal{B}(\mathit{{\rm Y}}(1S)\to \gamma A^0)·\mathcal{B}(A^0\to gg\mathrm{\text{or}}\mathrm{s}\overline{\mathrm{s}})$ ranging from ${10}^{-6}$ to ${10}^{-2}$ for $A^0$ masses in the range $0.5–9.0\mathrm{GeV}/c^2$.

We calculate the statistical entropy of a rotating hairy black hole by taking into account superradiant modes in the brick wall method. The UV cutoff is independent of the gravitational hair, which gives the well-defined area law of the entropy. It can be shown that the angular momentum and the energy of matter field depend on the gravitational hair. For the vanishing gravitational hair, it turns out that the energy for matter is related to both the black hole mass and the black hole angular momentum whereas the angular momentum for matter field is directly proportional to the angular momentum of the black hole.

We derive a holographic relation for the de Sitter (dS) static patch with the dual field theory defined on the observer horizon. The starting point is the duality of higher-spin theory on ${\mathrm{AdS}}_4$ and the $\mathsf{O}(N)$ vector model. We build on a similar analytic continuation as used recently to obtain a realization of dS/CFT and adapt it to the static patch. The resulting duality relates higher-spin theory on the ${\mathrm{dS}}_4$ static patch to a cutoff conformal field theory on the cylinder $\mathbb{R}\times {\mathrm{S}}^2$. The construction permits a derivation of the finite thermodynamic entropy associated to the horizon of the static patch from the dual field theory. As a further brick, we recover the spectrum of quasinormal frequencies from the correlation functions of the boundary theory. In the last part, we incorporate the dS/dS correspondence as an independent proposal for holography on dS and show that a concrete realization can be obtained by similar reasoning.

The new manifestation of conformal invariance for a massless scalar particle in a Riemannian spacetime of general relativity is found. Conformal transformations conserve the Hamiltonian and wave function in the Foldy-Wouthuysen representation. Similarity of manifestations of conformal invariance for massless scalar and Dirac particles is proved. New exact Foldy-Wouthuysen Hamiltonians are derived for both massive and massless scalar particles in a general static spacetime and in a frame rotating in the Kerr field approximated by a spatially isotropic metric. The latter case covers an observer on the ground of the Earth or on a satellite and takes into account the Lense-Thirring effect. High-precision formulas are obtained for an arbitrary spacetime metric. General quantum-mechanical equations of motion are derived. Their classical limit coincides with corresponding classical equations.

It is possible to show that there are three independent families of models describing a massive spin-2 particle via a rank-2 tensor. One of them contains the massive Fierz-Pauli model, the only case described by a symmetric tensor. The three families have different local symmetries in the massless limit and can not be interconnected by any local field redefinition. We show here, however, that they can be related with the help of a decoupled and nondynamic (spectator) field. The spectator field may be either an antisymmetric tensor $B_{\mu \nu }=-B_{\nu \mu }$, a vector $A_{\mu }$ or a scalar field $\phi$, corresponding to each of the three families. The addition of the extra field allows us to formulate master actions which interpolate between the symmetric Fierz-Pauli theory and the other models. We argue that massive gravity models based on the Fierz-Pauli theory are not expected to be equivalent to possible local self-interacting theories built up on top of the two new families of massive spin-2 models. The approach used here may be useful to investigate dual (nonsymmetric) formulations of higher-spin particles.

Doubts have been expressed on the universality of holographic/string-inspired quantization rules for the horizon areas of stationary black holes, or the products of their radii, already in 4-dimensional general relativity. Realistic black holes are not stationary but time-dependent. We produce three examples of 4-dimensional general-relativistic spacetimes containing dynamical black holes for at least part of the time, and we show that the quantization rules (even counting virtual horizons) cannot hold, except possibly at isolated instants of time, and do not seem to be universal.

The coalescence of a stellar-mass compact object into an intermediate-mass black hole (intermediate mass-ratio coalescence; IMRAC) is an important astrophysical source for ground-based gravitational-wave interferometers in the so-called advanced (or second-generation) configuration. However, the ability to carry out effective matched-filter-based searches for these systems is limited by the lack of reliable waveforms. Here we consider binaries in which the intermediate-mass black hole has a mass in the range $24{\mathrm{M}}_{\odot }–200{\mathrm{M}}_{\odot }$ with a stellar-mass companion having masses in the range $1.4{\mathrm{M}}_{\odot }–18.5{\mathrm{M}}_{\odot }$. In addition, we constrain the mass ratios, $q$, of the binaries to be in the range $1/140\le q\le 1/10$ and we restrict our study to the case of circular binaries with nonspinning components. We investigate the relative contribution to the signal-to-noise ratio (SNR) of the three different phases of the coalescence—inspiral, merger and ringdown—using waveforms computed within the effective one-body formalism matched to numerical relativity. We show that merger and ringdown contribute to a substantial fraction of the total SNR over a large portion of the mass parameter space, although in a limited portion the SNR is dominated by the inspiral phase. We further identify three regions in the IMRAC mass space in which (i) inspiral-only searches could be performed with losses in detection rates $L$ in the range $10\%\lesssim L\lesssim 27\%$, (ii) searches based on inspiral-only templates lead to a loss in detection rates in the range $27\%\lesssim L\lesssim 50\%$, and (iii) templates that include merger and ringdown are essential to prevent losses in detection rates greater than 50%. In addition we find that using inspiral-only templates as filters can lead to large biases in the estimates of the mass parameters of IMRACs. We investigate the effectiveness with which the inspiral-only portion of the IMRAC waveform space is covered by comparing several existing waveform families in this regime. We find that different waveform families are only marginally effective at describing one another, as measured by the “fitting factor.” Our results reinforce the importance of extensive numerical relativity simulations of IMRACs to validate and calibrate semianalytical waveform families and the need for further studies of suitable approximation schemes in this mass range.

We consider general relativistic homogeneous gravitational collapses for dust and radiation. We show that replacing the density profile with an effective density justified by some quantum gravity framework leads to the avoidance of the final singularity. The effective density acts on the collapsing cloud by introducing an isotropic pressure, which is negligible at the beginning of the collapse and becomes negative and dominant in the strong-field regime. Event horizons never form and therefore the outcome of the collapse is not a black hole, in the sense that there are no regions causally disconnected from future null infinity. Apparent horizons form when the mass of the object exceeds a critical value, disappear when the matter density approaches an upper bound and gravity becomes very weak (asymptotic-freedom regime), form again after the bounce as a consequence of the decrease in the matter density, and eventually disappear when the density becomes too low and the matter is radiated away. The possibility of detecting radiation coming from the high-density region of a collapsing astrophysical object in which classically there would be the creation of a singularity could open a new window to experimentally test theories of quantum gravity.

Superradiant scattering processes are studied in general relativistic systems which, unlike rotating and/or charged black holes, do not exhibit an event horizon. Inspired by Zel’dovich’s seminal works on the amplification of waves by a rotating cylinder, we analyze, in the context of general relativity, the possibility of superradiance for electromagnetic waves reflecting off a rotating star and for charged scalar perturbations impinging on a charged sphere. The role of energy dissipation in these systems is analyzed and compared with the role of the event horizon in black hole superradiance.

We study the polymeric nature of quantum matter fields using the example of a Friedmann-Lemaître-Robertson-Walker universe sourced by a minimally coupled massless scalar field. The model is treated in the symmetry reduced regime via deparametrization techniques, with the scale factor playing the role of time. Subsequently, the remaining dynamic degrees of freedom corresponding to the matter are polymer quantized. The analysis of the resulting genuine quantum dynamic shows that the big bang singularity is resolved, although with the form of the resolution differing significantly from that in the models with matter clocks: dynamically, the singularity is made passable rather than avoided. Furthermore, this analysis exposes crucial limitations to the so-called effective dynamic in loop quantum cosmology when applied outside of the most basic isotropic settings.

Recent work has demonstrated that it is important to constrain the dynamics of cosmological perturbations, in addition to the evolution of the background, if we want to distinguish among different models of the dark sector. Especially the anisotropic stress of the (possibly effective) dark energy fluid has been shown to be an important discriminator between modified gravity and dark energy models. In this paper we use approximate analytical solutions of the perturbation equations in the presence of viscosity to study how the anisotropic stress affects the weak lensing and galaxy power spectrum. We then forecast how sensitive the photometric and spectroscopic Euclid surveys will be to both the speed of sound and the viscosity of our effective dark energy fluid when using weak lensing tomography and the galaxy power spectrum. We find that Euclid alone can only constrain models with a very small speed of sound and viscosity, while it will need the help of other observables in order to give interesting constraints on models with a sound speed close to one. This conclusion is also supported by the expected Bayes factor between models.

We present updated constraints on the free-streaming of warm dark matter (WDM) particles derived from an analysis of the Lyman-$\alpha$ flux power spectrum measured from high-resolution spectra of 25 $z>4$ quasars obtained with the Keck High Resolution Echelle Spectrometer and the Magellan Inamori Kyocera Echelle spectrograph. We utilize a new suite of high-resolution hydrodynamical simulations that explore WDM masses of 1, 2 and 4 keV (assuming the WDM consists of thermal relics), along with different physically motivated thermal histories. We carefully address different sources of systematic error that may affect our final results and perform an analysis of the Lyman-$\alpha$ flux power with conservative error estimates. By using a method that samples the multidimensional astrophysical and cosmological parameter space, we obtain a lower limit $m_{\mathrm{WDM}}\gtrsim 3.3\mathrm{keV}$ ($2\sigma$) for warm dark matter particles in the form of early decoupled thermal relics. Adding the Sloan Digital Sky Survey Lyman-$\alpha$ flux power spectrum does not improve this limit. Thermal relics of masses 1, 2 and 2.5 keV are disfavored by the data at about the $9\sigma$, $4\sigma$ and $3\sigma$ C.L., respectively. Our analysis disfavors WDM models where there is a suppression in the linear matter power spectrum at (nonlinear) scales corresponding to $k=10h/\mathrm{Mpc}$ which deviates more than 10% from a Lambda cold dark matter model. Given this limit, the corresponding “free-streaming mass” below which the mass function may be suppressed is $\sim 2\times {10}^8{h}^{-1}{\mathrm{M}}_{\odot }$. There is thus very little room for a contribution of the free-streaming of WDM to the solution of what has been termed the small scale crisis of cold dark matter.

Starlight in the Universe impedes the passage of high energy (e.g., TeV) gamma rays due to positron-electron pair production. The history of this stellar radiation field depends upon observations of the star formation rate which themselves can only be interpreted in the context of a particular cosmology. For different equations of state of dark energy, the star formation rate data suggest a different density of stellar photons at a particular redshift and a different probability of arrival of gamma rays from distant sources. In this work we aim to show that this effect can be used to constrain the equation of state of dark energy. The current work is a proof of concept and we outline the steps that would have to be taken to place the method in a rigorous statistical framework which could then be combined with other more mature methods such as fitting supernova luminosity distances.

We analyze how recent computations of the shear viscosity $\eta$ in the core of superfluid neutron stars affect the $r$-mode instability window. We first analyze the contribution of superfluid phonons to the viscosity, both in their hydrodynamical and ballistic regime. We also consider the recent computation of $\eta$ arising from the collisions of electrons with electrons and protons by Shternin and Yakovlev, and discuss how the interactions among superfluid phonons and electrons might contribute to the shear viscosity. For assessing the $r$-mode instability window we compare the shear viscosity due to phonons in the hydrodynamical regime with respect to the shear viscosity due to electron collisions. Only at high temperatures the superfluid phonon contribution to $\eta$ starts to dominate the process of $r$-mode damping. While our results for the instability window are preliminary, as other dissipative processes should be taken into account as well, they differ from previous evaluations of the $r$-mode damping due to the shear viscosity in superfluid neutron stars.

In this paper we propose an effective description of the transition to deconfinement in the vicinity of a black hole. For this we adapt the approach that uses the dual quark condensate as order parameter for confinement, originally introduced in the context of lattice QCD, to a strongly interacting fermion effective field theory propagating on a curved background. We construct numerically the dual condensate and determine approximately the region of the deconfined phase. The present analysis suggests that quarks will be radiated directly by Hawking emission, while hadrons will form at the boundary of the deconfined region by “standard” nonperturbative QCD effects. This example provides a nontrivial setup to discuss how gravity affects confinement.

The magnetic dipole $G_M(Q^2)$, electric quadrupole $G_E(Q^2)$, and Coulomb quadrupole $G_C(Q^2)$ form factors, describing the spin-$3/2$ to spin-$1/2$ electromagnetic transitions, are investigated within the light cone QCD sum rules. The $Q^2$ dependence of these form factors, as well as ratios of electric quadrupole and Coulomb quadrupole form factors to the magnetic dipole form factors, are studied. We also compare our results on the magnetic dipole form factor with the prediction of the covariant spectator quark model.

Top-quark physics at the LHC may open a window to physics beyond the Standard Model and even lead us to an understanding of the phenomenon of “flavor.” However, current flavor data is a strong hint that no “new physics” with a generic flavor structure can be expected at the TeV scale. In turn, if there is “new physics” at the TeV scale, it must be “minimally flavor violating.” This has become a widely accepted assumption for “new physics” models. In this paper we propose a model-independent scheme to test minimal flavor violation for the anomalous charged $Wtq$, $q\in \{d,s,b\}$ and flavor-changing $Vtq$, $q\in \{u,c\}$ and $V\in \{Z,\gamma ,g\}$ couplings within an effective field theory framework, i.e., in a model-independent way. We perform a spurion analysis of our effective field theory approach and calculate the decay rates for the anomalous top-quark decays in terms of the effective couplings for different helicities by using a two-Higgs doublet model of type II, under the assumption that the top-quark is produced at a high-energy collision and decays as a quasi-free particle.