We discuss in detail a method to study transverse momentum dependent parton distribution functions (TMDs) using lattice QCD. To develop the formalism and to obtain first numerical results, we directly implement a bilocal quark-quark operator connected by a straight Wilson line, allowing us to study $T$-even, “process-independent” TMDs. Beyond results for $x$-integrated TMDs and quark densities, we present a study of correlations in $x$ and ${\mathit{k}}_{\perp }$. Our calculations are based on domain wall valence quark propagators by the LHP Collaboration calculated on top of gauge configurations provided by the MILC Collaboration with $N_f=2+1$ asqtad-improved staggered sea quarks.

Recently, we discovered and discussed non-Abelian duality in the quark vacua of $\mathcal{N}=2$ super-Yang-Mills theory with the $\mathrm{U}(N)$ gauge group and $N_f$ flavors ($N_f>N$). Both theories from the dual pair support non-Abelian strings, which confine monopoles. Now we introduce an $\mathcal{N}=2$-breaking deformation, a mass term $\mu {\mathcal{A}}^2$ for the adjoint fields. Starting from a small deformation, we eventually make it large, which enforces complete decoupling of the adjoint fields. We show that the above non-Abelian duality fully survives in the limit of $\mathcal{N}=1$ supersymmetric QCD (SQCD), albeit some technicalities change. For instance, non-Abelian strings which used to be Bogomol’nyi-Prasad-Sommerfield saturated in the $\mathcal{N}=2$ limit, cease to be saturated in $\mathcal{N}=1$ SQCD. Our duality is a distant relative of Seiberg’s duality in $\mathcal{N}=1$ SQCD. Both share some common features, but have many drastic distinctions. This is due to the fact that Seiberg’s duality apply to the monopole rather than quark vacua. More specifically, in our theory we deal with $N<N_f<\frac{3}{2}N$ massive quark flavors. We consider the vacuum in which $N$ squarks condense. Then we identify a crossover transition from weak to strong coupling. At strong coupling, we find a dual theory, $\mathrm{U}(N_f-N)$ SQCD, with $N_f$ light dyon flavors. Dyons condense triggering the formation of non-Abelian strings, which confine monopoles. Screened quarks and gauge bosons of the original theory decay into confined monopole-antimonopole pairs and form stringy mesons.

We present a new evolution system for Einstein’s field equations which is based on tetrad fields and conformally compactified hyperboloidal spatial hypersurfaces which reach future null infinity. The boost freedom in the choice of the tetrad is fixed by requiring that its timelike leg be orthogonal to the foliation, which consists of constant mean curvature slices. The rotational freedom in the tetrad is fixed by the 3D Nester gauge. With these conditions, the field equations reduce naturally to a first-order constrained symmetric hyperbolic evolution system which is coupled to elliptic equations for the gauge variables. The conformally rescaled equations are given explicitly, and their regularity at future null infinity is discussed. Our formulation is potentially useful for high accuracy numerical modeling of gravitational radiation emitted by inspiraling and merging black hole binaries and other highly relativistic isolated systems.

It is shown that the equations governing linearized gravitational (or electromagnetic) perturbations of the near-horizon geometry of any known extreme vacuum black hole (allowing for a cosmological constant) can be Kaluza-Klein reduced to give the equation of motion of a charged scalar field in ${\mathrm{AdS}}_2$ with an electric field. One can define an effective Breitenlöhner-Freedman bound for such a field. We conjecture that if a perturbation preserves certain symmetries then a violation of this bound should imply an instability of the full black hole solution. Evidence in favor of this conjecture is provided by the extreme Kerr solution and extreme cohomogeneity-1 Myers-Perry solution. In the latter case, we predict an instability in seven or more dimensions and, in five dimensions, we present results for operator conformal weights assuming the existence of a conformal field theory dual. We sketch a proof of our conjecture for scalar field perturbations.

We present a comprehensive study of primordial fluctuations generated from $G$ inflation, in which the inflaton Lagrangian is of the form $K(\varphi ,X)-G(\varphi ,X)\square \varphi$ with $X=-(\partial \varphi {)}^2/2$. The Lagrangian still gives rise to second-order gravitational and scalar field equations, and thus offers a more generic class of single-field inflation than ever studied, with a richer phenomenology. We compute the power spectrum and the bispectrum, and clarify how the non-Gaussian amplitude depends upon parameters such as the sound speed. In so doing we try to keep as great generality as possible, allowing for non slow-roll and deviation from the exact scale invariance.

A variational principle was recently suggested by Goenner, where an independent metric generates the spacetime connection. It is pointed out here that the resulting theory is equivalent to the usual Palatini theory. However, a bimetric reformulation of the variational principle leads to theories which are physically distinct from both the metric and the metric-affine ones, even for the Einstein-Hilbert action. They are obtained at a decoupling limit of $C$-theories, which contain also other viable generalizations of the Palatini theories.

We study nonperturbative improvement in SU(3) lattice gauge theory coupled to fermions in the fundamental and two-index symmetric representations. Our lattice action is defined with hypercubic smeared links incorporated into the Wilson–clover fermion kernel. Using standard Schrödinger-functional techniques, we estimate the clover coefficient $c_{\mathrm{SW}}$ and find that discretization errors are much smaller than in thin-link theories.

Recent CMS data significantly extend the exclusion limits for supersymmetry. We examine the impact of such data on global fits of the constrained minimal supersymmetric standard model (CMSSM) to indirect and cosmological data. By simulating supersymmetric signal events at the LHC, we construct a likelihood map for the recent CMS data, validating it against the exclusion region calculated by the experiment itself. A previous CMSSM global fit is then reweighted by our likelihood map. The CMS results nibble away at the high fit probability density region, transforming probability distributions for the scalar and gluino masses. The CMS search has a nontrivial effect on $\tan \beta$ due to correlations between the parameters implied by the fits to indirect data.

The Higgs boson may dominantly decay to four light jets through a light pseudoscalar intermediary: $h\to 2\eta \to 4j$, making reconstruction at the LHC particularly challenging. We explore the phenomenology of such “buried Higgs” scenarios in which the primary discovery channel of the Higgs is in cascade decays of superpartners. QCD backgrounds that would otherwise overwhelm the Higgs decay are suppressed by the requirement of high $p_T$ jets and large missing transverse momentum that are the typical signatures of TeV scale supersymmetry. Utilizing jet substructure techniques, we find that for buried Higgses in the 100–120 GeV range, a $5\sigma$ discovery can be expected with roughly $10–25{\mathrm{fb}}^{-1}$ of data at $E_{\mathrm{CM}}=14\mathrm{TeV}$. For lighter Higgs bosons, the signal is contaminated by hadronically decaying $W$ bosons, and discovery remains an unsolved challenge.

We have proposed to use an effective theory to describe interactions of an $N\overline{N}$ system. The effective theory can be constructed in analogy to the existing effective theory for an $NN$ system. In this work we study the next-to-leading order correction to $N\overline{N}$ scattering near the threshold in the effective theory. We find that the experimental data can be well described with the effective theory.

We adopt a bottom-up approach to constructing a new physics model to explain the CDF excess seen in dijets with an associated lepton and missing transverse energy. We find that the 145 GeV broad feature seen by CDF in the dijet invariant mass distribution can be explained by a $Z^{\prime }$ boson with a mass of 145 GeV that couples only to first generation quarks. After dijet resonance constraints are considered, a sizeable region of the parameter space favored by the CDF anomaly remains viable.

We report on a search for extremely-high energy neutrinos with energies greater than ${10}^6\mathrm{GeV}$ using the data taken with the IceCube detector at the South Pole. The data was collected between April 2008 and May 2009 with the half-completed IceCube array. The absence of signal candidate events in the sample of 333.5 days of live time significantly improves model-independent limits from previous searches and allows to place a limit on the diffuse flux of cosmic neutrinos with an $E^{-2}$ spectrum in the energy range $2.0\times {10}^6-6.3\times {10}^9\mathrm{GeV}$ to a level of $E^2\varphi \le 3.6\times {10}^{-8}\mathrm{GeV}{\mathrm{cm}}^{-2}{\sec }^{-1}{\mathrm{sr}}^{-1}$.

We explain why the analysis in our paper [Phys. Rev. D 69, 064033 (2004)] is relevant and correct.

It is shown here that the extraction of quasinormal modes within the first Born approximation of the scattering amplitude is mathematically not well-founded. Indeed, the constraints on the existence of the scattering amplitude integral lead to inequalities for the imaginary parts of the quasinormal mode frequencies. For instance, in the Schwarzschild case, $0\le {\omega }_I<\kappa$ (where $\kappa$ is the surface gravity at the horizon) invalidates the poles deduced from the first Born approximation method, namely, ${\omega }_n=in\kappa$.

We investigate infrared dynamics of the nonlinear sigma model in de Sitter space. In the presence of minimally coupled massless scalar fields, the de Sitter symmetry is dynamically broken and physical constants become time dependent. We find that the effective coupling constant of the nonlinear sigma model becomes time dependent. The power counting arguments of the infrared logarithms indicate that the effective cosmological constant also acquires time dependence. We find that such infrared logarithms cancel out in a perturbative investigation up to the two loop level. We further demonstrate a nonperturbative nonrenormalization of the cosmological constant in the large $N$ limit of the nonlinear sigma model.

The role of the dilaton field and its coupling to matter may result in a dilution of dark matter (DM) relic densities. This is to be contrasted with quintessence scenarios in which relic densities are augmented, due to modification of the expansion rate, since the Universe is not radiation dominated at DM decoupling. The dilaton field, besides this, affects relic densities through its coupling to dust which tends to decrease relic abundances. Thus two separate mechanisms compete with each other resulting, in general, in a decrease of the relic density. This feature may be welcomed and can help the situation if direct dark matter experiments point towards small neutralino-nucleon cross sections, implying small neutralino annihilation rates and hence large relic densities, at least in the popular supersymmetric scenarios. In the presence of a diluting mechanism, both experimental constraints can be met. The role of the dilaton for this mechanism has been studied in the context of the noncritical string theory but in this work we follow a rather general approach assuming that the dilaton dominates only at early eras long before big bang nucleosynthesis.

We discuss an extended standard model electroweak sector which contains a stable scalar dark matter particle, the $D$ boson. To search for the $D$ boson at the LHC we exploit the flavor-changing neutral current top quark decay, $t\to cDD$, mediated by the lightest standard model-like Higgs $h^0$ in a two Higgs doublet model framework. The branching ratio for $t\to cDD$ in this case can be as high as ${10}^{-3}$, after taking into account constraints arising from the $D$ boson relic abundance. With an integrated luminosity of $10(100){\mathrm{fb}}^{-1}$, the 14 TeV LHC can explore values of this branching ratio that are one (two) order of magnitude smaller in $t\overline{t}$ production with $t\overline{t}\to c\overline{b}{\ell }^{-}(\overline{c}b{\ell }^{+})+{\cancel{E}}_T$. For a $D$ boson mass $\lesssim 60\mathrm{GeV}$, $m_{h^0}\lesssim 2M_Z$, $10{\mathrm{fb}}^{-1}$ luminosity and a branching ratio $\mathrm{BR}(t\to cDD)\sim {10}^{-4}$, the estimated number of signal events at the 14 TeV LHC is of order 80.

We discuss the impact for light neutralinos in an effective minimal supersymmetric extension of the standard model of the recent results presented by the CMS and ATLAS Collaborations at the CERN Large Hadron Collider for a search of supersymmetry in proton-proton collisions at a center-of-mass energy of 7 TeV with an integrated luminosity of $35{\mathrm{pb}}^{-1}$. We find that, in the specific case of light neutralinos, efficiencies for the specific signature searched by ATLAS ($\mathrm{\text{jets}}+\mathrm{\text{missing transverse energy}}$ and an isolated lepton) imply a lower sensitivity compared to CMS (which searches for $\mathrm{\text{jets}}+\mathrm{\text{missing transverse energy}}$). Focusing on the CMS bound, if squark soft masses of the three families are assumed to be degenerate, the combination of the ensuing constraint on squark and gluino masses with the experimental limit on the $b\to s+\gamma$ decay imply a lower bound on the neutralino mass $m_{\chi }$ that can reach the value of 11.9 GeV, depending on the gluino mass. On the other hand, when the universality condition among squark soft parameters is relaxed, the lower bound on $m_{\chi }$ is not constrained by the CMS measurement and then remains at the value 7.5 GeV derived in previous papers.

We consider supersymmetric models where anomaly and gravity mediation give comparable contributions to the soft terms and discuss how this can be realized in a five-dimensional brane world. The gaugino mass pattern of anomaly mediation is preserved in such a hybrid setup. The flavorful gravity-mediated contribution cures the tachyonic slepton problem of anomaly mediation. The supersymmetric flavor puzzle is solved by alignment. We explicitly show how a working flavor-tachyon link can be realized with Abelian flavor symmetries and give the characteristic signatures of the framework, including $\mathcal{O}(1)$ slepton mass splittings between different generations and between doublets and singlets. This provides opportunities for same flavor dilepton edge measurements with missing energy at the Large Hadron Collider (LHC). Rare lepton decay rates could be close to their current experimental limit. Compared to pure gravity mediation, the hybrid model is advantageous because it features a heavy gravitino which can avoid the cosmological gravitino problem of gravity-mediated models combined with leptogenesis.

We investigate the parity-broken phase structure for staggered and naive fermions in the Gross-Neveu model as a toy model of QCD. We consider a generalized staggered Gross-Neveu model including two types of four-point interactions. We use generalized mass terms to split the doublers for both staggered and naive fermions. The phase boundaries derived from the gap equations show that the mass splitting of tastes results in an Aoki phase both in the staggered and naive cases. We also discuss the continuum limit of these models and explore taking the chirally symmetric limit by fine-tuning a mass parameter and two-coupling constants. This supports the idea that in lattice QCD we can derive one- or two-flavor staggered fermions by tuning the mass parameter, which are likely to be less expensive than Wilson fermions in QCD simulation.