We report a search for charmless hadronic decays of neutral $B$ mesons to the final state $K^{+}{K}^{-}{\pi }^0$. The results are based on a $711{\mathrm{fb}}^{-1}$ data sample that contains $772\times {10}^6$ $B\overline{B}$ pairs, and was collected at the ${\rm Y}(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. We find the first evidence for this decay with a significance of 3.5 standard deviations and measure its branching fraction as $\mathcal{B}(B^0\to K^{+}{K}^{-}{\pi }^0)=[2.17\pm 0.60(\mathrm{stat})\pm 0.24(\mathrm{syst})]\times {10}^{-6}$.

We discuss finite temperature phase diagrams of SU(N) gauge theory with massless fermions as a function of the number of fermion flavors. Inside the conformal window we find a phase boundary separating two different finite temperature phases. Below the conformal window we find different phase structures depending on if the beta function of the theory has a first or higher order zero at the lower boundary of the conformal window. We also outline how the associated behaviors will help in distinguishing different types of theories using lattice simulations.

We explore the signatures of quintessence and modified gravity theories in the relativistic description of galaxy clustering within a parametrized post-Friedmann framework. For this purpose, we develop a calibration method to consistently account for horizon-scale effects in the linear parametrized post-Friedmann perturbations of minimally and nonminimally coupled scalar-tensor theories and test it against the full model-specific fluctuations. We further study the relativistic effects in galaxy clustering for the normal and self-accelerating branches of the Dvali-Gabadadze-Porrati braneworld model as well as for phenomenological modifications of gravity. We quantify the impact of modified gravity and dark energy models on galaxy clustering by computing the velocity-to-matter density ratio $\mathcal{F}$, the velocity contribution $\mathcal{R}$, and the potential contribution $\mathcal{P}$ and give an estimate of their detectability in future galaxy surveys. Our results show that, in general, the relativistic correction contains additional information on gravity and dark energy, which needs to be taken into account in consistent horizon-scale tests of departures from $\Lambda \mathrm{CDM}$ using the galaxy-density field.

We study generic tests of strong-field general relativity using gravitational waves emitted during the inspiral of compact binaries. Previous studies have considered simple extensions to the standard post-Newtonian waveforms that differ by a single term in the phase. Here we improve on these studies by (i) increasing the realism of injections and (ii) determining the optimal waveform families for detecting and characterizing such signals. We construct waveforms that deviate from those in general relativity through a series of post-Newtonian terms, and find that these higher-order terms can affect our ability to test general relativity, in some cases by making it easier to detect a deviation, and in some cases by making it more difficult. We find that simple single-phase post-Einsteinian waveforms are sufficient for detecting deviations from general relativity, and there is little to be gained from using more complicated models with multiple phase terms. The results found here will help guide future attempts to test general relativity with advanced ground-based detectors.

The hadron-quark phase transition in the core of massive neutron stars is studied with a newly constructed two-phase model. For nuclear matter, a nonlinear Walecka type model with general nucleon-meson and meson-meson couplings, recently calibrated by Steiner, Hemper and Fischer, is taken. For quark matter, a modified Polyakov-Nambu—Jona-Lasinio model, which gives consistent results with lattice QCD data, is used. Most importantly, we introduce an isoscalar-vector interaction in the description of quark matter, and we study its influence on the hadron-quark phase transition in the interior of massive neutron stars. With the constraints of neutron star observations, our calculation shows that the isoscalar-vector interaction between quarks is indispensable if massive hybrids star exist in the universe, and its strength determines the onset density of quark matter, as well as the mass-radius relations of hybrid stars. Furthermore, as a connection with heavy-ion-collision experiments we give some discussions about the strength of isoscalar-vector interaction and its effect on the signals of hadron-quark phase transition in heavy-ion collisions, in the energy range of the NICA at JINR-Dubna and FAIR at GSI-Darmstadt facilities.

We present a global reanalysis of the most recent experimental data on azimuthal asymmetries in semi-inclusive deep inelastic scattering, from the HERMES and COMPASS Collaborations, and in $e^{+}{e}^{-}\to h_1{h}_{2}X$ processes, from the Belle Collaboration. The transversity and the Collins functions are extracted simultaneously, in the framework of a revised analysis in which a new parametrization of the Collins functions is also tested.

We study the signal of dark matter and photon associated production induced by the vector and axial-vector operators at the LHC, including the QCD next-to-leading order (NLO) effects. We find that the QCD NLO corrections reduce the dependence of the total cross sections on the factorization and renormalization scales, and the $K$ factors increase with the increasing of the dark matter mass, which can be as large as about 1.3 for both the vector and axial-vector operators. Using our QCD NLO results, we improve the constraints on the new physics scale from the results of the recent CMS experiment. Moreover, we show the Monte Carlo simulation results for detecting the $\gamma +{\mathrm{E̸}}_T$ signal at the QCD NLO level, and present the integrated luminosity needed for a $5\sigma$ discovery at the 14 TeV LHC. If the signal is not observed, the lower limit on the new physics scale can be set.

The holonomy correction is one of the main terms arising when implementing loop quantum gravity ideas at an effective level in cosmology. The recent construction of an anomaly-free algebra has shown that the formalism used, up to now, to derive the primordial spectrum of fluctuations was not correct. This paper aims at computing the tensor spectrum in a fully consistent way within this deformed and closed algebra.

In this paper, inspired by the holographic dual of the entanglement entropy, we consider the behavior of extremal, codimension two, spacelike surfaces in the background of three and four dimensional charged boson stars in asymptotically anti-de Sitter spacetime. We find conditions for which families of minimal area surfaces fail to contain the entire bulk spacetime and construct a phase diagram showcasing the transition between regimes. In addition, we use the relation between the star’s mass and the central density of the scalar field to argue for a possible instability of such hollow solutions. Finally, we discuss the consequences of our findings for the study of holographic duals of reduced density matrices.

We calculate the chameleon field potential for ultracold neutrons bouncing on top of one, or between two, neutron mirrors in the gravitational field of the Earth. For the resulting nonlinear equations of motion, we give approximate analytical solutions and compare them with exact numerical ones for which we propose the analytical fit. The obtained solutions may be used for the quantitative analysis of contributions of a chameleon field to the transition frequencies of quantum states of ultracold neutrons bound in the gravitational field of the Earth.

The postulates of black hole complementarity do not imply a firewall for infalling observers at a black hole horizon. The dynamics of the stretched horizon, that scrambles and reemits information, determines whether infalling observers experience anything out of the ordinary when entering a large black hole. In particular, there is no firewall if the stretched horizon degrees of freedom retain information for a time of the order of the black hole scrambling time.

In this paper it is shown how to obtain, without ever using the background classical equations of motion, a simple second order Hamiltonian involving the Mukhanov-Sasaki variable describing quantum linear scalar perturbations for the case of scalar fields with arbitrary potentials and arbitrary spacelike hypersurfaces. It is a generalization of previous works, where the scalar field potential was absent and the spacelike hypersurfaces were flat. This was possible due to the implementation of a new method, together with the Faddeev-Jackiw procedure for the constraint reduction. The resulting Hamiltonian can then be used to study the evolution of quantum cosmological perturbations in quantum backgrounds.

We present a simple toy model corresponding to a network of frustrated topological defects of domain walls or cosmic strings that exist previous to the standard slow-roll inflationary era of the Universe. Such a network (i) can produce a slower inflationary era than that of the standard scenario if it corresponds to a network of frustrated domain walls or (ii) can induce a vanishing universal acceleration; i.e., the Universe would expand at a constant speed, if it corresponds to a network of frustrated cosmic strings. Those features are phenomenologically modeled by a Chaplygin gas that can interpolate between a network of frustrated topological defects and a de Sitter–like or a power-law inflationary era. We show that this scenario can alleviate the quadrupole anomaly of the cosmic microwave background spectrum. Using the method of the Bogoliubov coefficients, we obtain the spectrum of the gravitational waves as would be measured today for the whole range of frequencies. We comment on the possible detection of this spectrum by the planned detectors like BBO and DECIGO.

We consider a geometrically thin, Keplerian disk in the orbital plane of a binary black hole (BHBH) consisting of a spinning primary and low-mass secondary (mass ratio $q\lesssim 1$). To account for the principle effects of general relativity (GR), we propose a modification of the standard Newtonian evolution equation for the (orbit-averaged) time-varying disk surface density. In our modified equation the viscous torque in the disk is treated in full GR, while the tidal torque is handled in the Newtonian limit. Our GR-hybrid treatment is reasonable because the tidal torque is concentrated near the orbital radius of the secondary and is most important prior to binary-disk decoupling, when the orbital separation is large and resides in the weak-field regime. The tidal torque on the disk diminishes during late merger and vanishes altogether following merger. By contrast, the viscous torque drives the flow into the strong-field region and onto the primary during all epochs. Following binary coalescence, the viscous torque alone governs the time-dependent accretion onto the remnant, as well as the temporal behavior, strength and spectrum of the aftermath electromagnetic radiation from the disk. We solve our GR-hybrid equation for a representative BHBH-disk system, identify several observable EM signatures of the merger, and compare results obtained for the gas and EM radiation with those found with the Newtonian prescription.

We introduce a new method for numerically evolving the full Einstein field equations in situations where the spacetime is dominated by a known background solution. The technique leverages the knowledge of the background solution to subtract off its contribution to the truncation error, thereby more efficiently achieving a desired level of accuracy. We demonstrate the method by applying it to the radial infall of a solar-type star into supermassive black holes with mass ratios $\ge {10}^6$. The self-gravity of the star is thus consistently modeled within the context of general relativity, and the star’s interaction with the black hole computed with moderate computational cost, despite the over five orders of magnitude difference in gravitational potential (as defined by the ratio of mass to radius). We compute the tidal deformation of the star during infall, and the gravitational wave emission, finding the latter is close to the prediction of the point-particle limit.

We derive the generalized Boltzmann equation (GBE) near equilibrium from the Kadanoff-Baym equation for quark excitation with ultrasoft momentum ($\sim g^{2}T$, where $g$ is the coupling constant and $T$ is the temperature) in quantum chromodynamics at extremely high $T$, and show that the equation is equivalent to the self-consistent equation derived in the resummed perturbation scheme used to analyze the quark propagator. We obtain the expressions of the dispersion relation, the damping rate, and the strength of a quark excitation with ultrasoft momentum by solving the GBE. We also show that the GBE enables us to obtain the equation determining the $n$-point function containing a pair of quarks and ($n-2$) gluon external lines whose momenta are ultrasoft.

Relativistic particles with spins $J>0$ are described by means of multicomponent wave functions which transform covariantly according to Lorentz-group representations that contain at rest the spin of interest. The symmetry group of space-time provides not one but an infinity of such representations which are equivalent for free particles but yield different electromagnetic couplings upon gauging; thus, the challenge is to develop criteria which allow us to select those of them which relate to physically detectable particles. We here take the position that the unitarity of the Compton scattering cross sections in the ultrarelativistic limit, when predicted by a consistent method for a spin-1 description, could provide such a criterion. We analyze the properties of massive fundamental spin-1 bosons transforming as antisymmetric tensors of second rank, $(1,0)\oplus (0,1)$. For this purpose, we employ the Poincaré covariant projector method, which provides consistent, gauge invariant, causal, and representation specific Lagrangians. This formalism yields a twofold extension of the Proca Lagrangian for the description of spin-1 bosons, first from an in-built $g=1$ value of the gyromagnetic ratio to an unspecified general $g\ne 1$, and then from single-parity to parity-doublet degrees of freedom. We find different results for Compton scattering in these theories and track the differences to the lack of universality of the vector-antisymmetric-tensor equivalence theorem which is specific only to Proca’s framework, and valid for $g=1$, while it is violated within the more general Poincaré covariant projector formalism. Our main result is that a finite Compton scattering differential cross section in the ultrarelativistic limit requires us to consider the contributions of both parities in $(1,0)\oplus (0,1)$. On that basis, we conclude that massive spin-1 bosons transforming as antisymmetric tensors are physical parity doublets.

Supersymmetric scenarios with $R$-parity conservation are becoming very constrained due to the lack of missing energy signals associated to heavy neutral particles, thus motivating scenarios with $R$-parity violation. In view of this, we consider a supersymmetric model with $R$-parity violation and extended by an anomalous horizontal $U(1{)}_H$ symmetry. A self-consistent framework with baryon-number violation is achieved along with a proper suppression for lepton-number violating dimension-five operators, so that the proton can be sufficiently stable. With the introduction of right-handed neutrinos, both Dirac and Majorana masses can be accommodated within this model. The implications for collider physics are discussed.

We revisit diffractive and exclusive $W^{\pm }X$ production at hadron colliders in different models for soft color exchanges. The process $pp\to p[W^{\pm }X]p$, and in particular a $W^{\pm }$ charge asymmetry, has been suggested as a way to discriminate diffractive processes as being due to pomeron exchange in Regge phenomenology or QCD-based color reconnection models. Our detailed analysis of the latter models at LHC energies shows, however, that they give similar results as pomeron models for leading protons and central $W^{\pm }X$ production, including a vanishing $W^{\pm }$ charge asymmetry. We demonstrate that soft color exchange models provide a continuous transition from diffractive to inelastic processes and thereby include the intrinsic asymmetry of inelastic interactions while being at the same time sensitive to the underlying hadronization models. Such sensitivity also concerns the differential distributions in proton momentum and $W^{\pm }$ transverse momentum, which opens possibilities to discriminate between different color reconnection models.