Vortons can be viewed as (flat space) field theory analogs of black rings in general relativity. They are made from loops of vortices, being sustained against collapse by the centrifugal force. In this work we discuss such configurations in the global version of Witten’s $U(1)\times U(1)$ theory. We first consider solutions in a flat spacetime background and show their nonuniqueness. The inclusion of gravity leads to new features. In particular, an ergoregion can occur. Also, similar to boson stars, we show that the vortons exist only in a limited frequency range. The coupling to gravity gives rise to a spiral-like frequency dependence of the mass and charge. New solutions of the model describing “semitopological vortons” and “di-vortons” are also discussed.

A new model-independent method is presented for the analysis of pulsar timing data and the estimation of the spectral properties of an isotropic gravitational wave background (GWB). Taking a Bayesian approach, we show that by rephrasing the likelihood we are able to eliminate the most costly aspects of computation normally associated with this type of data analysis. When applied to the International Pulsar Timing Array Mock Data Challenge data sets this results in speedups of approximately 2–3 orders of magnitude compared to established methods, in the most extreme cases reducing the run time from several hours on the high performance computer “DARWIN” to less than a minute on a normal work station. Because of the versatility of this approach, we present three applications of the new likelihood. In the low signal-to-noise regime we sample directly from the power spectrum coefficients of the GWB signal realization. In the high signal-to-noise regime, where the data can support a large number of coefficients, we sample from the joint probability density of the power spectrum coefficients for the individual pulsars and the GWB signal realization using a “guided Hamiltonian sampler” to sample efficiently from this high-dimensional ($\sim 1000$) space. Critically in both these cases we need make no assumptions about the form of the power spectrum of the GWB, or the individual pulsars. Finally, we show that, if desired, a power-law model can still be fitted during sampling. We then apply this method to a more complex data set designed to represent better a future International Pulsar Timing Array or European Pulsar Timing Array data release. We show that even in challenging cases where the data features large jumps of the order 5 years, with observations spanning between 4 and 18 years for different pulsars and including steep red noise processes we are able to parametrize the underlying GWB signal correctly. Finally we present a method for characterizing the spatial correlation between pulsars on the sky, making no assumptions about the form of that correlation, and therefore providing the only truly general Bayesian method of confirming a GWB detection from pulsar timing data.

Previous work established a universal form for the equation of motion of small bodies in theories of a metric and other tensor fields that have second-order field equations following from a covariant Lagrangian in four spacetime dimensions. Differences in the motion of the “same” body in two different theories are entirely accounted for by differences in the body’s effective mass and charges in those different theories. Previously the process of computing the mass and charges for a particular body was left implicit, to be determined in each particular theory as the need arises. I now obtain explicit expressions for the mass and charges of a body as surface integrals of the fields it generates, where the integrand is constructed from the symplectic current for the theory. This allows the entire prescription for computing the motion of a small body to be written down in a few lines, in a manner universal across bodies and theories. For simplicity I restrict to scalar and vector fields (in addition to the metric), but there is no obstacle to treating higher-rank tensor fields. I explicitly apply the prescription to work out specific equations for various body types in Einstein gravity, generalized Brans-Dicke theory (in both Jordan and Einstein frames), Einstein-Maxwell theory and the Will-Nordvedt vector-tensor theory. In the scalar-tensor case, this clarifies the origin and meaning of the “sensitivities” defined by Eardley and others, and provides explicit formulas for their evaluation.

Recent cosmic microwave background measurements at high multipoles from the South Pole Telescope and from the Atacama Cosmology Telescope seem to disagree in their conclusions for the neutrino and dark radiation properties. In this paper we set new bounds on the dark radiation and neutrino properties in different cosmological scenarios combining the ACT and SPT data with the nine-year data release of the Wilkinson Microwave Anisotropy Probe (WMAP-9), baryon acoustic oscillation data, Hubble Telescope measurements of the Hubble constant, and supernovae Ia luminosity distance data. In the standard three massive neutrino case, the two high multipole probes give similar results if baryon acoustic oscillation data are removed from the analyses and Hubble Telescope measurements are also exploited. A similar result is obtained within a standard cosmology with $N_{\mathrm{eff}}$ massless neutrinos, although in this case the agreement between these two measurements is also improved when considering simultaneously baryon acoustic oscillation data and Hubble Space Telescope measurements. In the $N_{\mathrm{eff}}$ massive neutrino case the two high multipole probes give very different results regardless of the external data sets used in the combined analyses. When considering extended cosmological scenarios with a dark energy equation of state or with a running of the scalar spectral index, the evidence for neutrino masses found for the South Pole Telescope in the three neutrino scenario disappears for all the data combinations explored here. Again, adding Hubble Telescope data seems to improve the agreement between the two high multipole cosmic microwave background measurements considered here. In the case in which a dark radiation background with unknown clustering properties is also considered, SPT data seem to exclude the standard value for the dark radiation viscosity $c_{\mathrm{vis}}^2=1/3$ at the $2\sigma$ C.L., finding evidence for massive neutrinos only when combining SPT data with baryon acoustic oscillation measurements.

In this paper, we compare brane inflation models with the Planck data and the pre-Planck data (which combines WAMP, ACT, SPT, BAO and $H_0$ data). The Planck data prefer a spectral index less than unity at more than $5\sigma$ confidence level, and a running of the spectral index at around $2\sigma$ confidence level. We find that the KKLMMT model can survive at the level of $2\sigma$ only if the parameter $\beta$ (the conformal coupling between the Hubble parameter and the inflaton) is less than $\mathcal{O}({10}^{-3})$, which indicates a certain level of fine-tuning. The IR DBI model can provide a slightly larger negative running of spectral index and red tilt, but in order to be consistent with the non-Gaussianity constraints from Planck, its parameter also needs fine-tuning at some level.

While, to ensure successful cosmology, dark matter (DM) must kinematically decouple from the standard model plasma very early in the history of the Universe, it can remain coupled to a bath of “dark radiation” until a relatively late epoch. One minimal theory that realizes such a scenario is the atomic dark matter model, in which two fermions oppositely charged under a new U(1) dark force are initially coupled to a thermal bath of “dark photons” but eventually recombine into neutral atomlike bound states and begin forming gravitationally bound structures. As dark atoms have (dark) atom-sized geometric cross sections, this model also provides an example of self-interacting DM with a velocity-dependent cross section. Delayed kinetic decoupling in this scenario predicts novel DM properties on small scales but retains the success of cold DM on larger scales. We calculate the atomic physics necessary to capture the thermal history of this dark sector and show significant improvements over the standard atomic hydrogen calculation are needed. We solve the Boltzmann equations that govern the evolution of cosmological fluctuations in this model and find in detail the impact of the atomic DM scenario on the matter power spectrum and the cosmic microwave background (CMB). This scenario imprints a new length scale, the dark-acoustic-oscillation scale, on the matter density field. This dark-acoustic-oscillation scale shapes the small-scale matter power spectrum and determines the minimal DM halo mass at late times, which may be many orders of magnitude larger than in a typical weakly interacting-massive-particle scenario. This model necessarily includes an extra dark radiation component, which may be favored by current CMB experiments, and we quantify CMB signatures that distinguish an atomic DM scenario from a standard $\Lambda \mathrm{CDM}$ model containing extra free-streaming particles. We finally discuss the impacts of atomic DM on galactic dynamics and show that these provide the strongest constraints on the model.

Recent data from the WMAP, ACT and SPT experiments provide precise measurements of the cosmic microwave background temperature power spectrum over a wide range of angular scales. The combination of these observations is well fit by the standard, spatially flat $\Lambda \mathrm{CDM}$ cosmological model, constraining six free parameters to within a few percent. The scalar spectral index, $n_s=0.9690\pm 0.0089$, is less than unity at the $3.5\sigma$ level, consistent with simple models of inflation. The damping tail of the power spectrum at high resolution, combined with the amplitude of gravitational lensing measured by ACT and SPT, constrains the effective number of relativistic species to be $N_{\mathrm{eff}}=3.28\pm 0.40$, in agreement with the standard model’s three species of light neutrinos.

The ${\gamma }^{*}\Lambda \to {\Sigma }^0$ transition form factors are investigated within the light-cone QCD sum rules method. Using the most general form of the interpolating current of ${\Sigma }^0$ baryon and the distribution amplitudes of $\Lambda$ baryon we calculate the $Q^2$ dependence of the electromagnetic form factors. Our results are compared with the predictions of the covariant spectator quark model.

A Higgs boson mass $\sim 126\mathrm{GeV}$ as determined by the LHC data requires a large loop correction, which in turn implies a large sfermion mass. Implication of this result for the stability of the proton in supersymmetric grand unified theories is examined including other experimental constraints along with the most recent result on cold dark matter from Planck. It is shown that over the allowed parameter space of supergravity unified models, proton lifetime is highly sensitive to the Higgs boson mass and a few GeV shift in its mass can change the proton decay lifetime for the mode $p\to \overline{\nu }{K}^{+}$ by as much as two orders of magnitude or more. An analysis is also given on the nature of radiative breaking of the electroweak symmetry in view of the high Higgs boson, and it is shown that most of the parameter space of universal and nonuniversal supergravity unified models lies on the hyperbolic branch of radiative breaking of the electroweak symmetry, while the ellipsoidal branch and the focal point regions are highly depleted and contain only a very small region of the allowed parameter space. Also discussed are the naturalness criteria when the proton stability constraints along with the electroweak symmetry breaking are considered together. It is shown that under the assumed naturalness criteria, the overall fine-tuning is improved for larger values of the scalar mass with the inclusion of the proton stability constraint. Thus, the naturalness criteria including proton stability along with electroweak symmetry breaking constraints tend to favor the weak scale of supersymmetry in the several TeV region. Implications for the discovery of supersymmetry in view of the high Higgs mass are briefly discussed.

We investigate chiral and conformal properties of the lattice QCD with eight flavors ($N_f=8$) through meson spectrum using the highly improved staggered quark (HISQ) action. We also compare our results with those of $N_f=12$ and $N_f=4$ which we study on the same systematics. We find that the decay constant $F_{\pi }$ of the pseudoscalar meson “pion” $\pi$ is nonzero, with its mass $M_{\pi }$ consistent with zero, both in the chiral limit extrapolation of the chiral perturbation theory. We also measure other quantities which we find are in accord with the $\pi$ data results: The $\rho$ meson mass is consistent with nonzero in the chiral limit, and so is the chiral condensate, with its value neatly coinciding with that from the Gell-Mann-Oakes-Renner relation in the chiral limit. Thus, our data for the $N_f=8$ QCD are consistent with the spontaneously broken chiral symmetry. Remarkably enough, while the $N_f=8$ data near the chiral limit are well described by the chiral perturbation theory, those for the relatively large fermion bare mass $m_f$ away from the chiral limit actually exhibit a finite-size hyperscaling relation, suggesting a large anomalous dimension ${\gamma }_m\sim 1$. This implies that there exists a remnant of the infrared conformality, and suggests that a typical technicolor (“one-family model”) as modeled by the $N_f=8$ QCD can be a walking technicolor theory having an approximate scale invariance with large anomalous dimension ${\gamma }_m\sim 1$.

A matrix Hamiltonian model is developed to address the finite-volume effects appearing in studies of baryon resonances in lattice QCD. The Hamiltonian model includes interaction terms in a transparent way and can be readily generalized to address multichannel problems. The eigenvalue equation of the model is exactly solvable and can be matched onto chiral effective field theory. The model is investigated in the case of $\Delta \to N\pi$ scattering. A robust method for determining the resonance parameters from lattice QCD is developed. It involves constraining the free parameters of the model based on the lattice spectrum in question. The method is tested in the context of a set of pseudodata, and a picture of the model dependence is obtained by examining a variety of regularization schemes in the model. A comparison is made with the Lüscher method, and it is found that the matrix Hamiltonian method is equally robust. Both methods are tested in a more realistic scenario, where a background interaction corresponding to direct $N\pi \leftrightarrow N\pi$ scattering is incorporated into the pseudodata. The resulting extraction of the resonance parameters associated with the $\Delta$ baryon resonance provides evidence that an effective field theory style of approach yields a successful realization of finite-volume effects in the context of baryon resonances.

We consider a generalization of the Thirring model in $2+1$ dimensions at finite density. We employ stochastic quantization and check for the applicability in the finite density case to circumvent the sign problem. To this end we derive analytical results in the heavy dense limit and compare with numerical ones obtained from a complex Langevin evolution. Furthermore, we make use of indirect indicators to check for incorrect convergence of the underlying complex Langevin evolution. The method allows the numerical evaluation of observables at arbitrary values of the chemical potential. We evaluate the results and compare to the ($0+1$)-dimensional case.

We make simulations with 2 flavor Wilson fermions to investigate the nature of the end points of Roberge-Weiss (RW) first order phase transition lines. The simulations are carried out at 9 values of the hopping parameter $\kappa$ ranging from 0.155 to 0.198 on different lattice spatial volume. The Binder cumulants, susceptibilities, and reweighted distributions of the imaginary part of the Polyakov loop are employed to determine the nature of the end points of RW transition lines. The simulations show that the RW end points are of first order at the values of $\kappa$ in our simulations.

We present a quantization condition for the spectrum of a system composed of three identical bosons in a finite volume with periodic boundary conditions. This condition gives a relation between the finite volume spectrum and infinite volume scattering amplitudes. The quantization condition presented is an integral equation that in general must be solved numerically. However, for systems with an attractive two-body force that supports a two-body bound state, a diboson, and for energies below the diboson breakup, the quantization condition reduces to the well-known Lüscher formula with exponential corrections in volume that scale with the diboson binding momentum. To accurately determine infinite volume phase shifts, it is necessary to extrapolate the phase shifts obtained from the Lüscher formula for the boson-diboson system to the infinite volume limit. For energies above the breakup threshold, or for systems with no two-body bound state (with only scattering states and resonances) the Lüscher formula gets power-law volume corrections and consequently fails to describe the three-particle system. These corrections are nonperturbatively included in the quantization condition presented.

We present search results based on next-to-leading order predictions for the pair production of color-adjoint leptons at the LHC. Quantum effects are sizable, dominated by pure QCD corrections, and sensitive to threshold effects. We illustrate the stabilization of scale dependencies and confirm an excellent agreement between fixed-order and multijet predictions for representative distributions. Finally, we examine the trademark collider signatures of leptogluon pairs. Based on the CMS leptoquark search we derive a mass bound of 1.2–1.3 TeV for charged leptogluons, significantly improving the constraints available in the literature.

Measured multiplicity distributions of primary charged particles produced in the forward rapidity region of the proton-proton ($pp$) collisions at the center-of-mass energy, $\sqrt{s}=7\mathrm{TeV}$, at the LHC have been analyzed in terms of the negative binomial distribution function. Like the multiplicity distributions in the midrapidity region for the $pp$ collisions at $\sqrt{s}=7\mathrm{TeV}$, the distributions for the minimum bias events in the forward region are also better described with the superposition of two negative binomail distributions, as proposed by a two-component model of particle production from two processes, the soft and the hard. However, the multiplicity distribution for the “hard-QCD” events in a large pseudorapidity window does not oblige the two-component model.

A central ingredient in establishing the properties of the newly discovered Higgs-like boson is the isolation of its production via vector boson fusion (VBF). With the typical experimental selection cuts, the VBF sample is contaminated by a $\sim 25\%$ fraction from $\mathrm{\text{Higgs}}+2$ jet production via gluon fusion (ggF), which has large perturbative uncertainties. We perform a detailed study of the perturbative uncertainties in the NLO predictions for $pp\to H+2$ jets via ggF used by the ATLAS and CMS Collaborations, with the VBF selection cuts of their current $H\to \gamma \gamma$ analyses. We discuss in detail the application of the so-called “Stewart-Tackmann method” for estimating fixed-order perturbative uncertainties in this case and also consider generalizations of it. Qualitatively, our results apply equally to other decay channels with similar VBF selection cuts. Typical VBF selections include indirect restrictions or explicit vetoes on additional jet activity, primarily to reduce non-Higgs backgrounds. We find that such restrictions have to be chosen carefully and are not necessarily beneficial for the purpose of distinguishing between the VBF and ggF production modes, since a modest reduction in the relative ggF contamination can be easily overwhelmed by its quickly increasing perturbative uncertainties.

Based on 106 million $\psi (3686)$ events collected with the BESIII detector at the BEPCII, the decay $\psi (3686)\to \omega K\overline{K}\pi$ is studied. Enhancements around $1.44\mathrm{GeV}/c^2$ and the $f_1(1285)$ are observed in the mass spectrum of $K\overline{K}\pi$, and the corresponding branching fraction (upper limit) is measured, as well as the branching fractions of $\psi (3686)\to \omega K^{*+}{K}^{-}+\mathrm{c}.\mathrm{c}.$ and $\psi (3686)\to \omega {\overline{K}}^{*0}{K}^0+\mathrm{c}.\mathrm{c}.$, all for the first time.