We determine masses and decay constants of heavy-heavy and heavy-charm pseudoscalar mesons as a function of heavy quark mass using a fully relativistic formalism known as highly improved staggered quarks for the heavy quark. We are able to cover the region from the charm quark mass to the bottom quark mass using MILC ensembles with lattice spacing values from 0.15 fm down to 0.044 fm. We obtain $f_{B_c}=0.427(6)\mathrm{GeV}$; $m_{B_c}=6.285(10)\mathrm{GeV}$ and $f_{{\eta }_b}=0.667(6)\mathrm{GeV}$. Our value for $f_{{\eta }_b}$ is within a few percent of $f_{{\rm Y}}$, confirming that spin effects are surprisingly small for heavyonium decay constants. Our value for $f_{B_c}$ is significantly lower than potential model values being used to estimate production rates at the LHC. We discuss the changing physical heavy-quark mass dependence of decay constants from heavy-heavy through heavy-charm to heavy-strange mesons. A comparison between the three different systems confirms that the $B_c$ system behaves in some ways more like a heavy-light system than a heavy-heavy one. Finally we summarize current results on decay constants of gold-plated mesons.

We study nonequilibrium dynamics of $SU(2)$ pure gauge theory starting from initial overpopulation, where intense classical gauge fields are characterized by a single momentum scale $Q_s$. Classical-statistical lattice simulations indicate a quick evolution towards an approximate scaling behavior with exponent $3/2$ at intermediate times. Remarkably, the value for the scaling exponent may be understood as arising from the leading $\mathcal{O}(g^2)$ contribution in the presence of a time-dependent background field. The phenomenon is associated to weak wave turbulence describing an energy cascade towards higher momenta. This particular aspect is very similar to what is observed for scalar theories, where an effective cubic interaction arises because of the presence of a time-dependent Bose condensate.

Signatures of new physics beyond the Standard Model are often characterized by large missing transverse energy (${\mathrm{E̸}}_T$) produced in association with multiple jets. The dominant Standard Model background to such processes comes from gauge-boson production in association with jets. A standard search strategy involves looking for an excess in the $m_{\mathrm{eff}}$ distribution, where $m_{\mathrm{eff}}={\mathrm{E̸}}_T+\sum _J{p}_J^T$ and $p_J^T$ denotes the transverse momentum of the $J$th jet. The region of large $m_{\mathrm{eff}}$ is dominated by jet production near threshold, giving rise to large Sudakov logarithms that can change the magnitude and shape of the $m_{\mathrm{eff}}$ distribution. We present an effective theory framework for the resummation of such threshold logarithms. We perform an analysis for exclusive jet production using the N-jettiness global event shape, which allows theoretical control to also be maintained over large logarithms induced by vetoing additional jets. As a first step, we give explicit numerical results with next-to-leading-log resummation for $pp\to \gamma +2$ jets in the large $m_{\mathrm{eff}}$ region.

We determine the neutrino spectra arising from low-mass ($4–10\mathrm{GeV}$) dark matter annihilating in the sun. We also determine the low-mass dark matter capture rates (element by element in the sun), assuming dark matter interacts either through elastic contact interactions, elastic long-range interactions, or inelastic contact interactions. These are the non-detector-specific data needed for determining the sensitivity of a neutrino detector to dark matter annihilating in the sun. As an application, we estimate the sensitivity of a one kiloton liquid scintillation neutrino detector (such as KamLAND) and LBNE (LAr-based) to low-mass dark matter with long-range interactions and compare this to the expected CDMS sensitivity. It is found that KamLAND’s sensitivity can exceed that obtainable from the current CDMS data set by up to two orders of magnitude.

We discuss the optimal setup for a low energy neutrino factory in order to achieve a $5\sigma$ discovery of a nonzero mixing angle ${\theta }_{13}$, a nonzero $CP$ phase ${\delta }_{CP}$, and the mass hierarchy. We explore parent muon energies in the range 5–16 GeV, and baselines in the range 500–5000 km. We present the results in terms of the reach in ${sin}^2{\theta }_{13}$, emphasizing the dependence of the optimal baseline on the true value of ${\delta }_{CP}$. We show that the sensitivity of a given setup typically increases with parent muon energy, reaching saturation for higher energies. The saturation energy is larger for longer baselines; we present an estimate of this dependence. In the light of the recent indications of a large ${\theta }_{13}$, we also determine how these preferences would change if indeed a large ${\theta }_{13}$ is confirmed. In such a case, the baselines $\sim 2500\mathrm{km}$ ($\sim 1500\mathrm{km}$) may be expected to lead to hierarchy determination (${\delta }_{CP}$ discovery) with the minimum exposure.

We present the first search for new phenomena in $Z\gamma$ final states with large missing transverse energy using data corresponding to an integrated luminosity of $6.2{\mathrm{fb}}^{-1}$ collected with the D0 experiment in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$. This signature is predicted in gauge-mediated supersymmetry-breaking models, where the lightest neutralino ${\tilde{\chi }}_1^0$ is the next-to-lightest supersymmetric particle and is produced in pairs, possibly through decay from heavier supersymmetric particles. The ${\tilde{\chi }}_1^0$ can decay either to a $Z$ boson or a photon and an associated gravitino that escapes detection. We exclude this model at the 95% C.L. for supersymmetry-breaking scales of $\Lambda <87\mathrm{TeV}$.

We show that given three Hermitian matrices, what one could call a fuzzy representation of a membrane, there is a well-defined procedure to define a set of oriented Riemann surfaces embedded in ${\mathbb{R}}^3$ using an index function defined for points in ${\mathbb{R}}^3$ that is constructed from the three matrices and the point. The set of surfaces is covariant under rotations, dilatations and translation operations on ${\mathbb{R}}^3$; it is additive on direct sums; and the orientation of the surfaces is reversed by complex conjugation of the matrices. The index we build is closely related to the Hanany-Witten effect. We also show that the surfaces carry information of a line bundle with connection on them. We discuss applications of these ideas to the study of holographic matrix models and black hole dynamics.

We study massive particle radiation from cosmic string kinks, and its observability in extremely high energy neutrinos. In particular, we consider the emission of moduli—weakly coupled scalar particles predicted in supersymmetric theories—from the kinks of cosmic string loops. Since kinks move at the speed of light on strings, moduli are emitted with large Lorentz factors, and eventually decay into many pions and neutrinos via hadronic cascades. The produced neutrino flux has energy $E\gtrsim {10}^{11}\mathrm{GeV}$, and is affected by oscillations and absorption (resonant and nonresonant). It is observable at upcoming neutrino telescopes such as JEM-EUSO, and the radio telescopes LOFAR and SKA, for a range of values of the string tension, and of the mass and coupling constant of the moduli.

In this paper, we study the question of effective field assignment to measured or nonperturbatively calculated spectral functions. The straightforward procedure is to approximate it by a sum of independent Breit-Wigner resonances and assign an independent field to each of these resonances. The problem with this idea is that it introduces new conserved quantities in the free model (the new particle numbers); therefore it changes the symmetry of the system. We avoid this inconsistency by representing each quantum channel with a single effective field, no matter how complicated the spectral function is. Thermodynamical characterization of the system is computed with this representation method, and its relation to the independent resonance approximation is discussed.

We present a coherent and operational strategy to calculate in a nonperturbative way, physical observables in light-front dynamics. This strategy is based on the decomposition of the state vector of any compound system in Fock components, and on the covariant formulation of light-front dynamics, together with the so-called Fock sector dependent renormalization scheme. We apply our approach to the calculation of the electromagnetic form factors of a fermion in the Yukawa model, in the nontrivial three-body Fock space truncation, for rather large values of the coupling constant. We find that once the renormalization conditions are properly taken into account, the form factors do not depend—within our numerical accuracy—on the regularization scale when the latter is much larger than the physical masses. We then extend the Fock space by including antifermion degrees of freedom.

The generalized uncertainty principle (GUP) has brought the idea of the existence of a minimum measurable length in quantum physics. Depending on this GUP, the nonrelativistic Hamiltonian at the Planck scale is modified. In this paper, we construct the kernel for this GUP-corrected Hamiltonian for a free particle by applying the Hamiltonian path integral approach and checking the validity conditions for this kernel thoroughly. Interestingly, the probabilistic interpretation of this kernel induces a momentum upper bound in the theory which is comparable with GUP-induced maximum momentum uncertainty.

We consider topologically twisted $N=4$ supersymmetric Yang-Mills theory on a four-manifold of the form $V=W\times {\mathbb{R}}_{+}$ or $V=W\times I$, where $W$ is a Riemannian three-manifold. Different kinds of boundary conditions apply at infinity or at finite distance. We verify that each of these conditions defines a “middle-dimensional” subspace of the space of all bulk solutions. Taking the two boundaries of $V$ into account should thus generically give a discrete set of solutions. We explicitly find the spherically symmetric solutions when $W=S^3$ endowed with the standard metric. For widely separated boundaries, these consist of a pair of solutions which coincide for a certain critical value of the boundary separation and disappear for even smaller separations.

We use a single site lattice in four dimensions to study the scaling of large $N$ Yang-Mills field coupled to a single massless Dirac fermion in the adjoint representation. We use the location of the strong to the weak coupling transition defined through the eigenvalues of the folded Wilson loop operator to set a scale. We do not observe perturbative scaling in the region studied in this paper. Instead, we observe that the scale changes very slowly with the bare coupling. The lowest eigenvalue of the overlap Dirac operator is another scale that shows similar behavior as a function of the lattice coupling.

We analyze the vector meson formulation of the Bogomol’nyi-Prasad-Sommerfield (BPS) Skyrme model in ($3+1$) dimensions, where the term of sixth power in first derivatives characteristic for the original, integrable BPS Skyrme model (the topological or baryon current squared) is replaced by a coupling between the vector meson ${\omega }_{\mu }$ and the baryon current. We find that the model remains integrable in the sense of generalized integrability and almost solvable (reducible to a set of two first-order ordinary differential equations) for any value of the baryon charge. Further, we analyze the appearance of topological solitons for two one-parameter families of one-vacuum potentials: the old Skyrme potentials and the so-called BPS potentials. Depending on the value of the parameters, we find several qualitatively different possibilities. In the massless case, we have a parameter region with no Skyrmions, a unique compact Skyrmion with a discontinuous first derivative at the boundary (equivalently, with a source term located at the boundary, which screens the topological charge), and Coulomb-like localized solitons. For the massive vector meson, besides the no-Skyrmion region and a unique $C$-compact soliton, we find exponentially as well as power-like localized Skyrmions. Further, we find (for a specific potential) BPS solutions, i.e., Skyrmions saturating a Bogomolny bound (both for the massless and massive vector mesons), which are unstable for higher values of the baryon charge. The properties of the model are finally compared with its baby version in ($2+1$) dimensions and with the original BPS Skyrme model, contributing to a better understanding of the latter.

As a continuation of a previous work, here, we examine the admittance of Birkhoff’s theorem in a class of higher derivative theories of gravity. This class is contained in a larger class of theories which are characterized by the property that the trace of the field equations are of second order in the metric. The action representing these theories are given by a sum of higher curvature terms. Moreover, the terms of a fixed order $k$ in the curvature are constructed by taking a complete contraction of $k$ conformal tensors. The general spherically (hyperbolic or plane) symmetric solution is then given by a static asymptotically Lifshitz black hole with the dynamical exponent equal to the spacetime dimensions. However, theories which are homogeneous in the curvature (i.e., of fixed order $k$) possess additional symmetry which manifests as an arbitrary conformal factor in the general solution. So, these theories are analyzed separately and have been further divided into two classes depending on the order and the spacetime dimensions.

We recently developed a local description of the energy, momentum and angular momentum carried by the linearized gravitational field, wherein the gravitational energy-momentum tensor displays positive energy density and causal energy flux, and the gravitational spin tensor describes purely spatial spin [1,2]. We now investigate the role these tensors play in a broader theoretical context, demonstrating for the first time that (a) they do indeed constitute Noether currents associated with the symmetry of the linearized gravitational field under translation and rotation and (b) they are themselves a source of gravity, analogous to the energy momentum and spin of matter. To prove (a) we construct a Lagrangian for linearized gravity (a covariantized Fierz-Pauli Lagrangian for a massless spin-2 field) and show that our tensors can be obtained from this Lagrangian using a standard variational technique for calculating Noether currents. This approach generates formulae that uniquely generalize our gravitational energy-momentum tensor and spin tensor beyond harmonic gauge: we show that no other generalization can be obtained from a covariantized Fierz-Pauli Lagrangian without introducing second derivatives in the energy-momentum tensor. We then construct the Belinfante energy-momentum tensor associated with our framework (combining spin and energy momentum into a single object) and as our first demonstration of (b) we establish that this Belinfante tensor appears as the second-order contribution to a perturbative expansion of the Einstein field equations, generating the gravitational field in a manner equivalent to the (Belinfante) energy-momentum tensor of matter. By considering a perturbative expansion of the Einstein-Cartan field equations, we then demonstrate that (b) can be realized without forming the Belinfante tensor: our energy-momentum tensor and spin tensor appear as the quadratic terms in separate field equations, generating gravity as distinct entities. Finally, we examine the role of field redefinitions within these perturbative expansions; in contrast to our tensors, the Landau-Lifshitz tensor is found to require a nonlocal field redefinition in order to be cast as a source of the gravitational field. In an appendix, we also give a brief treatment of the global quantities that our framework defines and verify their equivalence (within the quadratic approximation) to the energy momentum and angular momentum of Arnowitt, Deser, and Misner.

In a previous article [L. M. Butcher, et al., Phys. Rev. D 82, 104040 (2010).], we derived an energy-momentum tensor for linear gravity that exhibited positive energy density and causal energy flux. Here we extend this framework by localizing the angular momentum of the linearized gravitational field, deriving a gravitational spin tensor which possesses similarly desirable properties. By examining the local exchange of angular momentum (between matter and gravity) we find that gravitational intrinsic spin is localized, separately from “orbital” angular momentum, in terms of a gravitational spin tensor. This spin tensor is then uniquely determined by requiring that it obey two simple physically motivated algebraic conditions. Firstly, the spin of an arbitrary (harmonic-gauge) gravitational plane wave is required to flow in the direction of propagation of the wave. Secondly, the spin tensor of any transverse-traceless gravitational field is required to be traceless. (The second condition ensures that local field redefinitions suffice to cast our gravitational energy-momentum tensor and spin tensor as sources of gravity in a quadratic approximation to general relativity.) Additionally, the following properties arise in the spin tensor spontaneously: all transverse-traceless fields have purely spatial spin, and any field generated by a static distribution of matter will carry no spin at all. Following the structure of our previous paper, we then examine the (spatial) angular momentum exchanged between the gravitational field and an infinitesimal detector, and develop a microaveraging procedure that renders the process gauge-invariant. The exchange of nonspatial angular momentum (i.e., moment of energy) is also analyzed, leading us to conclude that a gravitational wave can displace the center of mass of the detector; this conclusion is also confirmed by a “first principles” treatment of the system. Finally, we discuss the spin carried by a gravitational plane wave.

We analyze the response function of an Unruh-DeWitt detector moving with time-dependent acceleration along a one-dimensional trajectory in Minkowski spacetime. To extract the physics of the process, we propose an adiabatic expansion of this response function. This expansion is also a useful tool for computing the click rate of detectors in general trajectories. The expansion is done in powers of the time derivatives of the acceleration (jerk, snap, and higher derivatives). At the lowest order, we recover a Planckian spectrum with temperature proportional to the acceleration of the detector at each instant of the trajectory. Higher orders in the expansion involve powers of the derivatives of the acceleration, with well-behaved spectral coefficients with different shapes. Finally, we illustrate this analysis in the case of an initially inertial trajectory that acquires a given constant acceleration in a finite time.

We identify different helicity degrees of freedom of Fierz-Paulian massive gravity around generic backgrounds. We show that the two-parameter family proposed by de Rham, Gabadadze, and Tolley always propagates five degrees of freedom and therefore is free from the Boulware-Deser ghost. The analysis has a number of by-products, among which (a) it shows how the original decoupling limit construction ensures ghost freedom of the full theory, (b) it reveals an enhanced symmetry of the theory around linearized backgrounds, and (c) it allows us to give an algorithm for finding dispersion relations. The proof naturally extends to generalizations of the theory with a reference metric different from Minkowski.

In Reference [V. P. Frolov and A. A. Shoom, Phys. Rev. D 84, 044026 (2011)], equations of the modified geometrical optics for circularly polarized photon trajectories in a stationary spacetime are derived by using a ($1+3$)-decomposed form of Maxwell’s equations. We derive the same results by using a four-dimensional covariant description. In our procedure, the null nature of the modified photon trajectory naturally appears and the energy flux is apparently null. We find that, in contrast to the standard geometrical optics, the inner product of the stationary Killing vector and the tangent null vector to the modified photon trajectory is no longer a conserved quantity along light paths. This quantity is furthermore different for left- and right-handed photon. A similar analysis is performed for gravitational waves and an additional factor of 2 appears in the modification due to the spin-2 nature of gravitational waves.