In this paper, we define covariant Galilean transformations in curved space-time and find all scalar field theories invariant under this symmetry. The Slotheon is a Galilean-invariant scalar field with a modified propagator such that, whenever gravity is turned on and energy conditions are not violated, it moves slower than in the canonical setup. This property is achieved by a nonminimal derivative coupling of the Slotheon to the Einstein tensor. We prove that spherically symmetric black holes cannot have Slotheonic hairs. We then notice that in small derivative regimes the theory has an asymptotic local shift symmetry whenever the noncanonical coupling dominates over the canonical one.

A study of the shear viscosity of hadrons and quarks in hybrid stars has been performed in the framework of the microscopic transport theory. The neutron-star structure has been determined employing the equation of state from the Brueckner theory with three-body force for the hadron phase, and the equation of state from the MIT bag model for the deconfined quark phase. The nucleon-nucleon cross sections in dense matter have been consistently calculated from the Brueckner $G$ matrix, whereas for the quark-quark cross sections the perturbative QCD has been adopted. Despite that the quark contribution to the shear viscosity is quite small at low temperature, the transition to the deconfined phase makes the equation of state much softer with the result that the baryon viscosity turns out to be enhanced instead of reduced in hybrid stars. The damping time scale of $r$-modes due to the shear viscosity has been evaluated for several stable configurations of a hybrid star and compared with the neutron-star spin-down time scale induced by the emission gravitation radiation from the $r$-modes. The enhancement of the total viscosity makes the viscosity time scale comparable with the gravitation radiation one at low temperature.

A detailed simulation study is performed for multi-$\tau$ signatures at the Large Hadron Collider, which can be used to probe additional Higgs bosons with lepton-specific Yukawa interactions. We here consider the two Higgs doublet model with the Type-X Yukawa interaction, where nonstandard Higgs bosons predominantly decay into tau leptons. These extra Higgs bosons can be pair produced at hadron colliders. Consequently, multi-$\tau$ originated signals appear in the final state as a promising signature of such a model. We find that the main background can be considerably reduced by requiring the high multiplicity of leptons and tau-jets with appropriate kinematical cuts in the final state. Thus, assuming the integrated luminosity of a hundred of inverse fb, the excess can be seen in various three- and four-lepton channels. With the integrated luminosity of thousands of inverse fb, the determination of the mass as well as ratios of leptonic decay branching ratios of these Higgs bosons would also be possible.

We use lattice simulations to study the single-site version of $SU(N)$ lattice gauge theory with two flavors of Wilson-Dirac fermions in the adjoint representation, a theory whose large-volume correspondent is expected to be conformal or nearly conformal. Working with $N$ as large as 53, we map out the phase diagram in the plane of bare ‘t Hooft coupling, $g^{2}N$, and of the lattice quark mass, am, and look for the region where the $Z_N^4$ center symmetry of the theory is intact. In this region one expects the large-$N$ equivalence of the single-site and infinite volume theories to be valid. As for the $N_f=1$ case (see [B. Bringoltz and S. R. Sharpe, Phys. Rev. D 80, 065031 (2009)]), we find that the center-symmetric region is large and includes both light fermion masses and masses at the cutoff scale. We study the $N$-dependence of the width of this region and find strong evidence that it remains of finite width as $N\to \infty$. Simulating with couplings as small as $g^{2}N=0.005$, we find that the width shrinks slowly with decreasing $g^{2}N$, at a rate consistent with analytic arguments. Within the center-symmetric region our results for the phase structure, when extrapolated to $N=\infty$, apply also for the large-volume theory, which is minimal walking technicolor at $N=\infty$. We find a first-order transition as a function of am for all values of $b$, which we argue favors that the theory is confining in the infrared. Finally, we measure the eigenvalue densities of the Wilson-Dirac operator and its Hermitian version, and use large Wilson loops to study the utility of reduction for extracting physical observables.

We calculate the masses of taste non-Goldstone pions and kaons in staggered chiral perturbation theory through next-to-leading order in the standard power counting. The results can be used to quantitatively understand taste violations in existing lattice data generated with staggered fermions and to extract the $u$, $d$, and $s$ quark masses and Gasser-Leutwyler parameters from the experimentally observed spectrum. The expressions for the non-Goldstone masses contain low-energy couplings unique to the non-Goldstone sector. With two exceptions these enter as coefficients of analytic terms; all the new couplings can be fixed by performing spectrum calculations. We report one-loop results for the quenched case and the fully dynamical and partially quenched $1+1+1$ and $2+1$ flavor cases in the chiral $SU(3)$ and $SU(2)$ theories.

Lattice QCD simulations have made significant progress in the calculation of nucleon electromagnetic form factors in the chiral regime in recent years. With simulation results achieving pion masses of order $\sim 180\mathrm{MeV}$, there is an apparent challenge as to how the physical regime is approached. By using contemporary methods in chiral effective field theory ($\chi \mathrm{EFT}$), both the quark-mass and finite-volume dependence of the isovector nucleon magnetic moment are carefully examined. The extrapolation to the physical point yields a result that is compatible with experiment, albeit with a combined statistical and systematic uncertainty of $\pm 10\%$. The extrapolation shows a strong finite-volume dependence; lattice sizes of $L>5\mathrm{fm}$ must be used to simulate results within $2\%$ of the infinite-volume result for the magnetic moment at the physical pion mass.

We present a Monte Carlo renormalization group study of the SU(2) gauge theory with two Dirac fermions in the adjoint representation. Using the two-lattice matching technique we measure the running of the coupling and the anomalous mass dimension. We find slow running of the coupling, compatible with an infrared fixed point. Assuming this running is negligible we find a vanishing anomalous dimension, $\gamma =-0.03(13)$, however without this assumption our uncertainty in the running of the coupling leads to a much larger range of allowed values, $-0.6\lesssim \gamma \lesssim 0.6$. We also attempt to measure the anomalous mass dimension using the stability matrix method. We discuss the systematic errors affecting the current analysis and possible improvements.

We investigate the self-energies of particles in an external magnetic field $B$. The dependence is generally of the type $\sqrt{P(B)}$ with $P$ a polynomial in $B$ and the participating masses. The nonanalytic point depends on the masses and charges of the involved particles and is unproblematic for stable particles but constrains the linear energy shift approximation for resonances. We recover an earlier reported condition when the self-energy can be expanded in $B$ and derive two more conditions. Furthermore, we obtain the $B$ dependent self-energies of the nucleon and $\Delta (1232)$-isobar in the $SU(2)$ covariant chiral perturbation theory.

This paper presents a search for anomalous production of multiple low-energy leptons in association with a $W$ or $Z$ boson using events collected at the CDF experiment corresponding to $5.1{\mathrm{fb}}^{-1}$ of integrated luminosity. This search is sensitive to a wide range of topologies with low-momentum leptons, including those with the leptons near one another. The observed rates of production of additional electrons and muons are compared with the standard model predictions. No indications of phenomena beyond the standard model are found. A 95% confidence level limit is presented on the production cross section for a benchmark model of supersymmetric hidden-valley Higgs production. Particle identification efficiencies are also provided to enable the calculation of limits on additional models.

In an unconventional realization of left-right symmetry, the particle corresponding to the left-handed neutrino ${\nu }_L$ [with $SU(2{)}_L$ interactions] in the right-handed sector, call it $n_R$ [with $SU(2{)}_R$ interactions], is not its Dirac mass partner, but a different particle which may be a dark-matter candidate. In parallel to leptogenesis in the $SU(2{)}_L$ sector, asymmetric production of $n_R$ may occur in the $SU(2{)}_R$ sector. This mechanism is especially suited for $n_R$ mass of order 1 to 10 keV, i.e. warm dark matter, which is a possible new paradigm for explaining the structure of the Universe at all scales.

A study of the substructure of jets with transverse momentum greater than $400\mathrm{GeV}/c$ produced in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV at the Fermilab Tevatron Collider and recorded by the CDF II detector is presented. The distributions of the jet mass, angularity, and planar flow are measured for the first time in a sample with an integrated luminosity of $5.95{\mathrm{fb}}^{-1}$. The observed substructure for high mass jets is consistent with predictions from perturbative quantum chromodynamics.

We present a detailed examination of the color-dipole picture of low-$x$ deep inelastic scattering. We discriminate model-independent results, not depending on a specific parametrization of the dipole cross section, from model-dependent ones. The model-independent results include the ratio of the longitudinal to the transverse photoabsorption cross section at large $Q^2$ or, equivalently, the ratio of the longitudinal to the unpolarized proton structure function, $F_L(x,Q^2)=0.27F_2(x,Q^2)$, as well as the low-$x$ scaling behavior of the total photoabsorption cross section ${\sigma }_{{\gamma }^{*}p}(W^2,Q^2)={\sigma }_{{\gamma }^{*}p}(\eta (W^2,Q^2))$ as $\log (1/\eta (W^2,Q^2))$ for $\eta (W^2,Q^2)<1$, and as $1/\eta (W^2,Q^2)$ for $\eta (W^2,Q^2)\gg 1$. Here, $\eta (W^2,Q^2)$ denotes the low-$x$ scaling variable, $\eta (W^2,Q^2)=(Q^2+m_0^2)/{\Lambda }_{\mathrm{sat}}^2(W^2)$, with ${\Lambda }_{\mathrm{sat}}^2(W^2)$ being the saturation scale. The model-independent analysis also implies $\underset{W^2\to \infty ,Q^2\mathrm{fixed}}{lim}{\sigma }_{{\gamma }^{*}p}(W^2,Q^2)/{\sigma }_{\gamma p}(W^2)\to 1$ at any photon virtuality $Q^2$ for asymptotically large energy, $W$. Consistency with evolution in perturbative QCD evolution determines the underlying gluon distribution and the numerical value of $C_2=0.29$ in the expression for the saturation scale, ${\Lambda }^2(W^2)\sim (W^2{)}^{C_2}$. In the model-dependent analysis, by restricting the mass of the actively contributing $q\overline{q}$ fluctuations by an energy-dependent upper bound, we extend the validity of the color-dipole picture to the region of $\eta (W^2,Q^2)>10$, where $Q^2$ reaches values of a few hundred ${\mathrm{GeV}}^2$. The theoretical results agree with the world data on deep inelastic scattering for $0.036{\mathrm{GeV}}^2\le Q^2\le 316{\mathrm{GeV}}^2$, with $x\cong Q^2/W^2$ being limited by approximately $x\le 0.01$.

We report a study of final states containing a $W$ boson and hadronic jets, produced in proton-proton collisions at a center-of-mass energy of 7 TeV. The data were collected with the ATLAS detector at the CERN LHC and comprise the full 2010 data sample of $36{\mathrm{pb}}^{-1}$. Cross sections are determined using both the electron and muon decay modes of the $W$ boson and are presented as a function of inclusive jet multiplicity, $N_{\mathrm{jet}}$, for up to five jets. At each multiplicity, cross sections are presented as a function of jet transverse momentum, the scalar sum of the transverse momenta of the charged lepton, missing transverse momentum, and all jets, the invariant mass spectra of jets, and the rapidity distributions of various combinations of leptons and final-state jets. The results, corrected for all detector effects and for all backgrounds such as diboson and top quark pair production, are compared with particle-level predictions from perturbative QCD. Leading-order multiparton event generators, normalized to the next-to-next-to-leading-order total cross section for inclusive $W$-boson production, describe the data reasonably well for all measured inclusive jet multiplicities. Next-to-leading-order calculations from MCFM, studied here for $N_{\mathrm{jet}}\le 2$, and BlackHat-Sherpa, studied here for $N_{\mathrm{jet}}\le 4$, are found to be mostly in good agreement with the data.

We study oscillons, extremely long-lived localized oscillations of a scalar field, with three different potentials: quartic, in sine-Gordon model and in a new class of convex potentials. We use an absorbing boundary at the end of the lattice to remove emitted radiation. The energy and the frequency of an oscillon evolve in time and are well fitted by a constant component and a decaying, radiative part obeying a power law as a function time. The power spectra of the emitted radiation show several distinct frequency peaks where oscillons release energy. In two dimensions, and with suitable initial conditions, oscillons do not decay within the range of the simulations, which in quartic theory reach ${10}^8$ time units. While it is known that oscillons in three-dimensional quartic theory and sine-Gordon model decay relatively quickly, we observe a surprising persistence of the oscillons in the convex potential with no sign of demise up to ${10}^7$ time units. This leads us to speculate that an oscillon in such a potential could actually live infinitely long both in two and three dimensions.

Recently it has been recognized that in compactified $\mathrm{\text{string}}/M$ theories that satisfy cosmological constraints, it is possible to derive some robust and generic predictions for particle physics and cosmology with very mild assumptions. When the matter and gauge content below the compactification scale is that of the minimal supersymmetric standard model (MSSM), it is possible to make precise predictions. In this case, we predict that there will be a single standard model-like Higgs boson with a calculable mass $105\mathrm{GeV}\lesssim M_h\lesssim 129\mathrm{GeV}$ depending on $\tan \beta$ (the ratio of the Higgs vevs in the MSSM). For $\tan \beta >7$, the prediction is $122\mathrm{GeV}\lesssim M_h\lesssim 129\mathrm{GeV}$.