Recent observational evidence supports an accelerating expansion of the Universe during the present epoch. It is commonly incorporated into standard cosmology by the introduction of exotic matter (which violates the strong energy condition) known as dark energy (DE). As an event horizon exists for an accelerating universe, there has been much work on universal thermodynamics, i.e., thermodynamics of a universe bounded by an apparent or event horizon. Recently, thermodynamical equilibrium has been examined for both types of horizons. In the present work we show that universal thermodynamics with an event horizon is favored by DE from the point of view of an equilibrium thermodynamical prescription.

Gravitational waves emitted during compact binary coalescences are a promising source for gravitational-wave detector networks. The accuracy with which the location of the source on the sky can be inferred from gravitational-wave data is a limiting factor for several potential scientific goals of gravitational-wave astronomy, including multimessenger observations. Various methods have been used to estimate the ability of a proposed network to localize sources. Here we compare two techniques for predicting the uncertainty of sky localization—timing triangulation and the Fisher information matrix approximations—with Bayesian inference on the full, coherent data set. We find that timing triangulation alone tends to overestimate the uncertainty in sky localization by a median factor of 4 for a set of signals from nonspinning compact object binaries ranging up to a total mass of $20M_{\odot }$, and the overestimation increases with the mass of the system. We find that average predictions can be brought to better agreement by the inclusion of phase consistency information in timing-triangulation techniques. However, even after corrections, these techniques can yield significantly different results to the full analysis on specific mock signals. Thus, while the approximate techniques may be useful in providing rapid, large scale estimates of network localization capability, the fully coherent Bayesian analysis gives more robust results for individual signals, particularly in the presence of detector noise.

In this work we study the collider phenomenology of a compressed supersymmetric model with the gluino ($\tilde{g}$) and the lightest neutralino (${\tilde{\chi }}_1^0$). All other sparticles are assumed to be heavy. We consider gluino pair production at the 14 TeV LHC and present the mass reach of the gluino as a function of mass splitting between the gluino and the lightest neutralino. We find that the gluino mass below 1 TeV can be excluded at 95% C.L. with an integrated luminosity of $100{\mathrm{fb}}^{-1}$ for the extreme degenerate case where the mass separation between the gluino and the lightest neutralino is about 20 GeV. On the other hand, the lower bound on the mass of the gluino increases to 1.2–1.3 TeV if the mass splitting between the gluino and ${\tilde{\chi }}_1^0$ is about 200 GeV. This result shows that for a degenerate gluino, the current mass limit may approximately extend up to 400–500 GeV at the 14 TeV LHC.

The two-pion contribution from low energies to the muon magnetic moment anomaly, although small, has a large relative uncertainty since in this region the experimental data on the cross sections are neither sufficient nor precise enough. It is therefore of interest to see whether the precision can be improved by means of additional theoretical information on the pion electromagnetic form factor, which controls the leading-order contribution. In the present paper, we address this problem by exploiting analyticity and unitarity of the form factor in a parametrization-free approach that uses the phase in the elastic region, known with high precision from the Fermi–Watson theorem and Roy equations for $\pi \pi$ elastic scattering as input. The formalism also includes experimental measurements on the modulus in the region 0.65–0.70 GeV, taken from the most recent $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}$ experiments, and recent measurements of the form factor on the spacelike axis. By combining the results obtained with inputs from CMD2, SND, BABAR, and KLOE, we make the predictions $a_{\mu }^{\pi \pi ,\mathrm{LO}}[2m_{\pi },0.30\mathrm{GeV}]=(0.553\pm 0.004)\times {10}^{-10}$ and $a_{\mu }^{\pi \pi ,\mathrm{LO}}[0.30\mathrm{GeV},0.63\mathrm{GeV}]=(133.083\pm 0.837)\times {10}^{-10}$. These are consistent with the other recent determinations and have slightly smaller errors.

The entanglement extended Polyakov–Nambu–Jona-Lasinio model at zero chemical potential in the presence of an external magnetic field is studied. The effect of the entanglement parametrization is analyzed, in particular, on the pseudocritical transition temperatures and on the thermodynamical properties of the model. The model predicts that the coincidence or not of both chiral and deconfinement transition temperatures, in the presence of an external magnetic field, depends on the entanglement parametrization chosen.

Stronger constraints on the pseudoscalar coupling constants of an axion and axion-like particles with a proton and a neutron are obtained from measurements of the thermal Casimir-Polder force between a Bose-Einstein condensate of ${}^{87}\mathrm{Rb}$ atoms and a ${\mathrm{SiO}}_2$ plate. For this purpose, the additional force acting between a condensate cloud and a plate due to two-axion exchange is calculated. The obtained constraints refer to the axion masses from 0.1 meV to 0.3 eV which overlap with the region from 0.01 to 10 meV considered at the moment as the most prospective.

Dark matter self-interactions can affect the small scale structure of the Universe, reducing the central densities of dwarfs and low surface brightness galaxies in accord with observations. From a particle physics point of view, this points toward the existence of a 1–100 MeV particle in the dark sector that mediates self-interactions. Since mediator particles will generically couple to the Standard Model, direct detection experiments provide sensitive probes of self-interacting dark matter. We consider three minimal mechanisms for coupling the dark and visible sectors: photon kinetic mixing, $Z$ boson mass mixing, and the Higgs portal. Self-interacting dark matter motivates a new benchmark paradigm for direct detection via momentum-dependent interactions, and ton-scale experiments will cover astrophysically motivated parameter regimes that are unconstrained by current limits. Direct detection is a complementary avenue to constrain velocity-dependent self-interactions that evade astrophysical bounds from larger scales, such as those from the bullet cluster.

We consider flavor constraints on, and collider signatures of, asymmetric dark matter (ADM) via higher dimension operators. In the supersymmetric models we consider, $R$-parity-violating (RPV) operators carrying $B-L$ interact with $n$ dark matter particles $X$ through an interaction of the form $W=X^n{\mathcal{O}}_{B-L}$, where ${\mathcal{O}}_{B-L}=q\ell d^c$, $u^c{d}^c{d}^c$, $\ell \ell e^c$. This interaction ensures that the lightest ordinary supersymmetric particle is unstable to decay into the $X$ sector, leading to a higher multiplicity of final state particles and reduced missing energy at a collider. Flavor-violating processes place constraints on the scale of the higher dimension operator, impacting whether the LOSP decays promptly. While the strongest limitations on RPV from $n-\overline{n}$ oscillations and proton decay do not apply to ADM, we analyze the constraints from meson mixing, $\mu -e$ conversion, $\mu \to 3e$ and $b\to s{\ell }^{+}{\ell }^{-}$. We show that these flavor constraints, even in the absence of flavor symmetries, allow parameter space for prompt decay to the $X$ sector, with additional jets and leptons in exotic flavor combinations. We study the constraints from existing 8 TeV LHC Supersymmetry (SUSY) searches with (i) 2–6 jets plus missing energy and (ii) 1–2 leptons, 3–6 jets plus missing energy, comparing the constraints on ADM-extended supersymmetry with the usual supersymmetric simplified models.

In this paper, we study the extent to which $CP$ parity of a Higgs boson, and more generally its anomalous couplings to gauge bosons, can be measured at the LHC and a future electron-positron collider. We consider several processes, including Higgs boson production in gluon and weak boson fusion and production of a Higgs boson in association with an electroweak gauge boson. We consider decays of a Higgs boson including $ZZ,WW,\gamma \gamma$, and $Z\gamma$. A matrix element approach to three production and decay topologies is developed and applied in the analysis. A complete Monte Carlo simulation of the above processes at proton and $e^{+}{e}^{-}$ colliders is performed and verified by comparing it to an analytic calculation. Prospects for measuring various tensor couplings at existing and proposed facilities are compared.

We construct the next-to-leading-order chiral Lagrangian for scalar and pseudoscalar densities defined using the gradient flow, for flow times much smaller than the square of the pion wavelength. We calculate the chiral condensate and the pion decay constant to this order from operators at positive flow time, and confirm results obtained earlier in the chiral limit. We also calculate the quark-mass dependence of the scales $t_0$ and $w_0$ defined from the scalar gluon density and find that nonanalytic terms in the quark mass only enter at next-to-next-to-leading order.

We present results for the low-mass Drell-Yan (DY) production in proton-proton collisions at the LHC in the color dipole formalism. The DY differential cross sections at $\sqrt{s}=7\mathrm{TeV}$ as a function of dilepton rapidity, transverse momentum, and invariant mass are discussed. We impose kinematical cuts related to the low-mass DY production investigated by the ATLAS and LHCb Collaborations.

A detailed study of nucleon parton distribution functions is performed within a radiative next-to-next-to-leading-order (NNLO) parton model whose low-scale input is rigidly described by wave functions which include quarks and dressing a meson cloud. The light-front Hamiltonian dynamics fixes the three-quark wave functions, and the meson cloud is introduced by means of high-order Fock components in time-ordered perturbation theory in the infinite momentum frame. Nonstrange as well as strange meson-baryon fluctuations are considered ($\pi$, $\rho$, $\omega$, $K$, and $K^{*}$, together with $N$, $\mathrm{\Delta }$, $\mathrm{\Lambda }$, and $\mathrm{\Sigma }$) and the effects on strange and nonstrange parton distributions investigated showing the large effects due to (nonstrange) sea asymmetries and the delicate balance of the strange asymmetry. The nonstrange and the strange components, the valence as well as the gluon distributions, are compared with available experimental data confirming the need of both nonperturbative degrees of freedom and perturbative (NNLO) radiative effects.

We present theoretical predictions for five-jet production in proton-proton collisions at next-to-leading-order accuracy in QCD. Inclusive as well as differential observables are studied for collision energies of 7 and 8  TeV. In general the next-to-leading-order corrections stabilize the theoretical predictions with respect to scale variations. In the case of the inclusive jet cross sections, we compare with experimental data where possible and find reasonable agreement. We observe that the four-to-three and five-to-four jet ratios show better perturbative convergence than the known three-to-two ratio and are promising candidates for future ${\alpha }_s$ measurements. Furthermore, we present a detailed analysis of uncertainties related to parton distribution functions. The full color virtual matrix elements used in the computation were obtained with the NJet package [1], a publicly available library for the evaluation of one-loop amplitudes in massless QCD.

Although the meson decay amplitude described by a two-point function may be regarded as one of the simplest possible physical observables, it is interesting that this apparently simple amplitude bears abundant fundamental information on QCD vacuum dynamics and chiral symmetry. The light-front zero-mode issue of the vector meson decay constant $f_V$ is in this respect highly nontrivial and deserves careful analysis. We discuss the zero-mode issue in the light-front quark model (LFQM) prediction of $f_V$ from the perspective of the vacuum fluctuation consistent with the chiral symmetry of QCD. We extend the exactly solvable, manifestly covariant Bethe-Salpeter model calculation to the more phenomenologically accessible, realistic light-front quark model and present a self-consistent covariant description of $f_V$, analyzing the twist-2 and twist-3 quark-antiquark distribution amplitudes with even chirality.

The overall characteristics of the solar and atmospheric neutrino oscillation are approximately consistent with a tribimaximal form of the mixing matrix $U$ of the lepton sector. Exact tribimaximal mixing leads to ${\theta }_{13}=0$. However, recent results from the Daya Bay and RENO experiments have established a nonzero value for ${\theta }_{13}$. Keeping the leading behavior of $U$ as tribimaximal, we use a generalized Friedberg-Lee neutrino mass model along with a complementary ansatz to incorporate a nonzero ${\theta }_{13}$ along with $CP$ violation. We generalize this model in two stages: In the first stage, we assume $\mu -\tau$ symmetry and add imaginary components which leads to nonzero phases. In the second stage, we add a perturbation with real components which breaks the $\mu -\tau$ symmetry, and this leads to a nonzero value for ${\theta }_{13}$. The combination of these two generalizations leads to $CP$ violation. Using only two sets of the experimental data, we can fix all of the parameters of our model and predict not only values for the other experimental data, which agree well with the available data, but also the masses of neutrinos and the $CP$-violating phases and parameters. These predictions include the following: $⟨m_{{\nu }_e}⟩\approx (0.033-0.037)\mathrm{eV}$, $⟨m_{{\nu }_{\mu }}⟩\approx (0.043-0.048)\mathrm{eV}$, $⟨m_{{\nu }_{\tau }}⟩\approx (0.046-0.051)\mathrm{eV}$, and $59.21°\lesssim \delta \lesssim 59.34°$.

We present next-to-next-to-leading order (NNLO) parton distribution functions (PDFs) from the CTEQ-TEA group. The CT10NNLO PDF fit is based on essentially the same global data sets used in the CT10 and CT10W NLO PDF analyses. After exploring the goodness of the fits to the HERA combined data and the Tevatron jet data, we present various predictions at NNLO accuracy for both existing and forthcoming precision measurements from the CERN Large Hadron Collider. The range of variations in the gluon distribution introduced by correlated systematic effects in inclusive jet production is also examined.

A search is presented for new particles in an extension to the Standard Model that includes a heavy Higgs boson ($H^0$), an intermediate charged Higgs-boson pair ($H^{\pm }$), and a light Higgs boson ($h^0$). The analysis searches for events involving the production of a single heavy neutral Higgs boson which decays to the charged Higgs boson and a $W$ boson, where the charged Higgs boson subsequently decays into a $W$ boson and the lightest neutral Higgs boson decaying to a bottom–antibottom-quark pair. Such a cascade results in a $W$-boson pair and a bottom–antibottom-quark pair in the final state. Events with exactly one lepton, missing transverse momentum, and at least four jets are selected from a data sample corresponding to an integrated luminosity of $20.3{\mathrm{fb}}^{-1}$, collected by the ATLAS detector in proton-proton collisions at $\sqrt{s}=8\mathrm{TeV}$ at the LHC. The data are found to be consistent with Standard Model predictions, and 95% confidence-level upper limits are set on the product of cross section and branching ratio. These limits range from 0.065 to 43 pb as a function of $H^0$ and $H^{\pm }$ masses, with $m_{h^0}$ fixed at 125 GeV.

Correspondences between black holes and fluids have been discussed in two different frameworks, the fluid/gravity correspondence and membrane paradigm. Recently, it has been discussed that these two theories can be understood as the same theory if the cutoff surface is placed slightly outside the horizon. The bulk viscosity is different for these two theories, but it does not contribute to physics since the fluid becomes incompressible in the near horizon limit. In the AdS/CFT correspondence, it is known that the fluid becomes compressible and the bulk viscosity is zero, apart from the near horizon limit. In this paper, we consider the fluid/gravity correspondence in asymptotically non-AdS geometries. We put the cutoff surface near but at a finite distance from the horizon. Then, the model becomes the membrane paradigm with compressible fluid. We show that the bulk viscosity is not negative at least within the linear response regime. We also discuss the higher derivative corrections in the stress-energy tensor.

We look at the response of a nonlinearly coupled scalar field in an asymptotically AdS black brane geometry and find a behavior very similar to that of known dissipative nonlinear systems like the chaotic pendulum. Transition to chaos proceeds through a series of period-doubling bifurcations. The presence of dissipation, crucial to this behavior, arises naturally in a black hole background from the ingoing conditions imposed at the horizon. AdS/CFT translates our solution to a chaotic response of $\mathcal{O}$, the operator dual to the scalar field. Our setup can also be used to study quenchlike behavior in strongly coupled nonlinear systems.