We construct explicitly the canonical transformation which controls the full dependence (local and nonlocal) of the vertex functional of a Yang-Mills theory on a background field. After showing that the canonical transformation found is nothing but a direct field-theoretic generalization of the Lie transform of classical analytical mechanics, we comment on a number of possible applications, and, in particular, the nonperturbative implementation of the background field method on the lattice, the background field formulation of the two-particle irreducible formalism, and, finally, the formulation of the Schwinger-Dyson series in the presence of topologically nontrivial configurations.

There is experimental evidence for a direct $CP$ asymmetry in singly Cabibbo suppressed $D$ decays, $\Delta A_{CP}\sim 0.006$. Naive expectations are that the standard model contribution to $\Delta A_{CP}$ is an order of magnitude smaller. We explore the possibility that a major part of the asymmetry comes from supersymmetric contributions. The leading candidates are models where the flavor structure of the trilinear scalar couplings is related to the structure of the Yukawa couplings via approximate flavor symmetries, particularly $U(1)$, $[U(1){]}^2$ and $U(2)$. The recent hints for a lightest neutral Higgs boson with mass around 125 GeV support the requisite order one trilinear terms. The typical value of the supersymmetric contribution to the asymmetry is $\Delta A_{CP}^{\mathrm{SUSY}}\sim 0.001$, but it could be accidentally enhanced by order one coefficients.

We discuss the possibility of the cosmic coincidence generating the ratio of baryon asymmetry to dark matter in a Stueckelberg $U(1)$ extension of the standard model and of the minimal supersymmetric standard model. For the $U(1)$, we choose $L_{\mu }-L_{\tau }$ which is anomaly free and can be gauged. The dark matter candidate arising from this extension is a singlet of the standard model gauge group but is charged under $L_{\mu }-L_{\tau }$. Solutions to the Boltzmann equations for relics in the presence of asymmetric dark matter are discussed. It is shown that the ratio of the baryon asymmetry to dark matter consistent with the current WMAP data, i.e., the cosmic coincidence, can be successfully explained in this model with the depletion of the symmetric component of dark matter from resonant annihilation via the Stueckelberg gauge boson. For the extended minimal supersymmetric standard model model, it is shown that one has a two-component dark matter picture with asymmetric dark matter being the dominant component and the neutralino being the subdominant component (i.e., with relic density a small fraction of the WMAP cold dark matter value). Remarkably, the subdominant component can be detected in direct detection experiments such as SuperCDMS and XENON-100. Further, it is shown that the class of Stueckelberg models with a gauged $L_{\mu }-L_{\tau }$ will produce a dramatic signature at a muon collider with the $\sigma ({\mu }^{+}{\mu }^{-}\to {\mu }^{+}{\mu }^{-},{\tau }^{+}{\tau }^{-})$ showing a detectable $Z^{\prime }$ resonance while $\sigma ({\mu }^{+}{\mu }^{-}\to e^{+}{e}^{-})$ is devoid of this resonance. Within the above frameworks, we discuss several broad classes of models both above and below the electroweak phase transition temperature. Asymmetric dark matter arising from a $U(1{)}_{B-L}$ Stueckelberg extension is also briefly discussed. Finally, in the models we propose the asymmetric dark matter does not oscillate and there is no danger of it being washed out from oscillations.

We discuss the possibility that colliding dark matter particles in the form of neutralinos may be gravitationally boosted near the supermassive black hole at the Galactic center so that they can have enough collision energy to annihilate into a stau pair. Since in some phenomenologically favored supersymmetric models the mass splitting between the neutralino and the lightest stau, one of the two scalar superpartners of the tau lepton, is a few GeV, this channel may be allowed. In addition, staus can decay only into a tau lepton and another neutralino. We calculate the gamma ray spectrum and flux generated by the tau pair discussing the observability of the obtained features.

We study the Skyrme model of baryons with quantum chiral anomaly of QCD in magnetic backgrounds, and suggest a possible induction of a novel structure of electric charge inside the baryons. Due to the anomaly-induced gauged Wess-Zumino term $\sim ({\pi }_0+\mathrm{multipion})\overrightarrow{E}·\overrightarrow{B}$, the Skyrmions giving a local pion condensation $⟨({\pi }_0+\mathrm{multipion})⟩\ne 0$ would produce a local charge source, in the background magnetic field $\overrightarrow{B}\ne 0$. Since the appearance of the total additional electric charge on the baryon looks unrealistic and surprising, we discuss the validity of our detailed evaluation of the anomaly effects.

We discuss the possible power counting schemes that can be applied in the effective field theory description of heavy meson molecules, such as the $X(3872)$ or the recently discovered $Z_b(10610)$ and $Z_b(10650)$ states. We argue that the effect of coupled channels is suppressed by at least two orders in the effective field theory expansion, meaning that they can be safely ignored at lowest order. The role of the one pion exchange potential between the heavy mesons, and, in particular, the tensor force, is also analyzed. By using techniques developed in atomic physics for handling power-law singular potentials, which have been also successfully employed in nuclear physics, we determine the range of center-of-mass momenta for which the tensor piece of the one pion exchange potential is perturbative. In this momentum range, the one pion exchange potential can be considered a subleading order correction, leaving at lowest order a very simple effective field theory consisting only of contact-range interactions.

We devise tests for a new physics origin of the recently measured direct $CP$ violation in singly Cabibbo-suppressed $D$ decays. The tests take the form of sum rules for the $CP$ asymmetries in various $D$ decays. They are based on the fact that within the standard model $CP$ violation arises from interference of the dominant tree amplitudes with the $\Delta I=1/2$ penguin amplitudes. The sum rules would be violated if the observed $CP$ violation is due to new physics contributions to the effective weak Hamiltonian that change the isospin by $\Delta I=3/2$.

In the context of the standard model with a fourth generation, we explore the allowed mass spectra in the fourth-generation quark and lepton sectors as functions of the Higgs mass. Using the constraints from unitarity and oblique parameters, we show that a heavy Higgs allows large mass splittings in these sectors, opening up new decay channels involving $W$ emission. Assuming that the hints for a light Higgs do not yet constitute an evidence, we work in a scenario where a heavy Higgs is viable. A Higgs heavier than $\sim 800\mathrm{GeV}$ would in fact necessitate either a heavy quark decay channel $t^{\prime }\to b^{\prime }W/b^{\prime }\to t^{\prime }W$ or a heavy lepton decay channel ${\tau }^{\prime }\to {\nu }^{\prime }W$ as long as the mixing between the third and fourth generations is small. This mixing tends to suppress the mass splittings and hence the $W$-emission channels. The possibility of the $W$-emission channel could substantially change the search strategies of fourth-generation fermions at the LHC and impact the currently reported mass limits.

Both the ATLAS and CMS Collaborations have sought for effects beyond pure next-to-leading order in dijet observables, with the goal to distinguish between the perturbative descriptions provided by a next-to-leading order plus collinear-resummation calculation and by the resummation of wide-angle, hard emissions. In this paper, we identify regions of phase space in dijet production where some observables receive large corrections beyond next-to-leading order and study their theoretical description with two tools that perform these two different resummations: the POWHEG BOX and HEJ. Furthermore, we suggest analyses where the predictions from POWHEG and HEJ can be clearly distinguished experimentally.

We studied the feasibility of the measurement of Higgs pair creation at a photon linear collider. From the sensitivity to the anomalous self-coupling of the Higgs boson, the optimum $\gamma \gamma$ collision energy was found to be around 270 GeV for a Higgs mass of $120\mathrm{GeV}/c^2$. We found that large backgrounds such as $\gamma \gamma \to W^{+}{W}^{-}$, $ZZ$, and $b\overline{b}b\overline{b}$ can be suppressed if correct assignment of tracks to parent partons is achieved and Higgs pair events can be observed with a statistical significance of $\sim 5\sigma$ by operating the photon linear collider for 5 years.

We study the process $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{\pi }^{+}{\pi }^{-}\gamma$, with a photon emitted from the initial-state electron or positron, using $454.3{\mathrm{fb}}^{-1}$ of data collected with the BABAR detector at SLAC, corresponding to approximately 260 000 signal events. We use these data to extract the nonradiative $\sigma (e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{\pi }^{+}{\pi }^{-})$ cross section in the energy range from 0.6 to 4.5 GeV. The total uncertainty of the cross section measurement in the peak region is less than 3%, higher in precision than the corresponding results obtained from energy scan data.

The deconfinement phase transition of SU(2) Yang-Mills theory is investigated in the Hamiltonian approach in Coulomb gauge assuming a quasiparticle picture for the grand canonical gluon ensemble. The thermal equilibrium state is found by minimizing the free energy with respect to the quasigluon energy. Above the deconfinement phase transition the ghost form factor remains infrared divergent but its infrared exponent is approximately halved, while the gluon energy, being infrared divergent in the confined phase, becomes infrared finite in the deconfined phase. For the effective gluon mass we find a critical exponent of 0.37. Using the lattice results for the gluon propagator to fix the scale, the deconfinement transition temperature is obtained in the range of 275 to 290 MeV.

Causal dynamical triangulations (CDT) is a proposal for a theory of quantum gravity, which implements a path-integral quantization of gravity as the continuum limit of a sum over piecewise flat spacetime geometries. We use Monte Carlo simulations to analyze the phase transition lines bordering the physically interesting de Sitter phase of the four-dimensional CDT model. Using a range of numerical criteria, we present strong evidence that the so-called A–C transition is first order, while the B–C transition is second order. The presence of a second-order transition may be related to an ultraviolet fixed point of quantum gravity and thus provide the key to probing physics at and possibly beyond the Planck scale.

We study black holes in the recently proposed ghost-free theory with two gravitons, one of which is massive and another is massless. These black holes possess a regular event horizon which is common for both metrics and has the same values of the surface gravity and Hawking temperature with respect to each metric. The ratio of the event horizon radii measured by the two metrics is a free parameter that labels the solutions. We present a numerical evidence for their existence and find that they comprise several classes. Black holes within each class approach the same AdS-type asymptotic at infinity but differ from each other in the event horizon vicinity where the short-range massive modes reside. In addition, there are solutions showing a curvature singularity at a finite proper distance from the horizon. For some special solutions the graviton mass may become effectively imaginary, causing oscillations around the flat metric at infinity. The only asymptotically flat black hole we find—the Schwarzschild solution obtained by identifying the two metrics—seems to be exceptional, since changing even slightly its horizon boundary conditions completely changes the asymptotic behavior at infinity. We also construct globally regular solutions describing “lumps of pure gravity” which can be viewed as black hole remnants in the limit where the event horizon shrinks. Finally, adding a matter source we obtain globally regular and asymptotically flat solutions exhibiting the Vainstein mechanism of recovery of General Relativity in a finite region.

We study the problem of self-energy of charges in higher-dimensional static spacetimes. Application of regularization methods of quantum field theory to calculation of the classical self-energy of charges leads to model-independent results. The correction to the self-energy of a scalar charge due to the gravitational field of black holes of the higher-dimensional Majumdar-Papapetrou spacetime is calculated exactly. It proves to be zero in even dimensions, but it acquires nonzero value in odd-dimensional spacetimes. The origin of the self-energy correction in odd dimensions is similar to the origin of the conformal anomalies in quantum field theory in even-dimensional spacetimes.

Gauge invariance of scalar perturbations is studied together with the associated equations of motion. Extending the methods developed in Hamiltonian general relativity, the Hamilton-Jacobi equation is investigated into the details in the framework of loop quantum gravity. The gauge-invariant observables are built, and their equations of motions are reviewed both in the Hamiltonian and Lagrangian approaches. This method is applied to scalar perturbations with either holonomy or inverse-volume corrections.

Upper limits on the spin-independent as well as spin-dependent elastic scattering cross sections of low mass ($\sim 2–20\mathrm{GeV}$) weakly interacting massive particles (WIMPs ) with protons, imposed by the upper limit on the neutrino flux from WIMP annihilation in the Sun given by the Super-Kamiokande (S-K) experiment, and their compatibility with the “DAMA-compatible” regions of the WIMP parameter space—the regions of the WIMP mass versus cross-section parameter space within which the annual modulation signal observed by the DAMA/LIBRA experiment is compatible with the null results of other direct-detection experiments—are studied within the framework of a self-consistent model of the finite-size dark matter halo of the Galaxy. The halo model includes the gravitational influence of the observed visible matter of the Galaxy on the phase-space distribution function of the WIMPs constituting the Galaxy’s dark matter halo in a self-consistent manner. Unlike in the “standard halo model” used in earlier analyses, the velocity distribution of the WIMPs in our model is non-Maxwellian, with a high-velocity cutoff determined self-consistently by the model itself. The parameters of the model are determined from a fit to the rotation curve data of the Galaxy. We find that, for our best-fit halo model, for spin-independent interaction, while the S-K upper limits do not place additional restrictions on the DAMA-compatible region of the WIMP parameter space if the WIMPs annihilate dominantly to $\overline{b}b$ and/or $\overline{c}c$, portions of the DAMA-compatible region can be excluded if WIMP annihilations to ${\tau }^{+}{\tau }^{-}$ and $\nu \overline{\nu }$ occur at larger than 35% and 0.4% levels, respectively. For spin-dependent interaction, on the other hand, the restrictions on the possible annihilation channels are much more stringent: they rule out the entire DAMA region if WIMPs annihilate to ${\tau }^{+}{\tau }^{-}$ and $\nu \overline{\nu }$ final states at greater than $\sim 0.05\%$ and 0.0005% levels, respectively, and/or to $\overline{b}b$ and $\overline{c}c$ at greater than $\sim 0.5\%$ levels. The very latest results from the S-K Collaboration [T. Tanaka et al., Astrophys. J. 742, 78 (2011)] make the above constraints on the branching fractions of various WIMP annihilation channels even more stringent by roughly a factor of 3–4.

Recently it has been shown that imposing Petrov-like condition on the boundary may reduce the Einstein equation to the Navier-Stokes equation in the nonrelativistic and near-horizon limit. In this paper we extend this framework to a spacetime with a cosmological constant. By explicit construction we show that the Navier-Stokes equation can be derived from both black brane background and spatially curved spacetime. We also conjecture that imposing Petrov-like condition on the boundary should be equivalent to the conventional method using the hydrodynamical expansion of the metric in the near-horizon limit.

We present results from a search for gravitational-wave bursts in the data collected by the LIGO and Virgo detectors between July 7, 2009 and October 20, 2010: data are analyzed when at least two of the three LIGO-Virgo detectors are in coincident operation, with a total observation time of 207 days. The analysis searches for transients of duration $\lesssim 1\mathrm{s}$ over the frequency band 64–5000 Hz, without other assumptions on the signal waveform, polarization, direction or occurrence time. All identified events are consistent with the expected accidental background. We set frequentist upper limits on the rate of gravitational-wave bursts by combining this search with the previous LIGO-Virgo search on the data collected between November 2005 and October 2007. The upper limit on the rate of strong gravitational-wave bursts at the Earth is 1.3 events per year at 90% confidence. We also present upper limits on source rate density per year and ${\mathrm{Mpc}}^3$ for sample populations of standard-candle sources. As in the previous joint run, typical sensitivities of the search in terms of the root-sum-squared strain amplitude for these waveforms lie in the range $\sim 5\times {10}^{-22}{\mathrm{Hz}}^{-1/2}$ to $\sim 1\times {10}^{-20}{\mathrm{Hz}}^{-1/2}$. The combination of the two joint runs entails the most sensitive all-sky search for generic gravitational-wave bursts and synthesizes the results achieved by the initial generation of interferometric detectors.