We study the polarized Drell-Yan processes from the collision of two spin-$1/2$ hadrons at order $1/Q$ based on the framework of transverse-momentum dependent factorization. We give the complete twist-three results of total 16 independent structure functions in terms of twist-two and twist-three transverse-momentum dependent distribution functions.

We investigate the possibility of detecting Majorana neutrinos at the $e^{+}{e}^{-}$ Next Linear Collider (NLC). We study the $l_j^{\mp }{l}_k^{\mp }+\mathrm{\text{jets}}$ ($l_j\equiv e$, $\mu$, $\tau$) final states which are, due to leptonic number violation, a clear signature for intermediate Majorana neutrino contributions. Such signals (final leptons of the same sign) are not possible if the heavy neutrinos have Dirac nature. The interactions between Majorana neutrinos and the standard model particles are obtained from an effective Lagrangian approach. As for the background, we considered the standard model reaction $e^{+}{e}^{-}\to W^{+}{W}^{+}{W}^{-}{W}^{-}$, with two $W^{\prime }$s decaying into jets and two $W^{\prime }$s decaying into $l^{\pm }+\nu (\overline{\nu })$, producing extra light neutrinos which avoid the detection. We present our results for the total cross section as a function of the neutrino mass and the center-of-mass energy. We also show the discovery region as a function of the Majorana neutrino mass and the effective coupling.

We present measurements of production cross sections of single top quarks in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ in a data sample corresponding to an integrated luminosity of $5.4{\mathrm{fb}}^{-1}$ collected by the D0 detector at the Fermilab Tevatron Collider. We select events with an isolated electron or muon, an imbalance in transverse energy, and two, three, or four jets, with one or two of them containing a bottom hadron. We obtain an inclusive cross section of $\sigma (p\overline{p}\to tb+X,tqb+X)=3.43{\pm }_{0.74}^{0.73}\mathrm{pb}$ and use it to extract the CKM matrix element $0.79<|V_{tb}|\le 1$ at the 95% C.L. We also measure $\sigma (p\overline{p}\to tb+X)=0.68{\pm }_{0.35}^{0.38}\mathrm{pb}$ and $\sigma (p\overline{p}\to tqb+X)=2.86{\pm }_{0.63}^{0.69}\mathrm{pb}$ when assuming, respectively, $tqb$ and $tb$ production rates as predicted by the standard model.

We construct the type IIB supergravity solutions describing D3-branes ending on 5-branes, in the near-horizon limit of the D3-branes. Our solutions are holographically dual to the four dimensional (4D) $\mathcal{N}=4$ $SU(N)$ supersymmetric-Yang-Mills (SYM) theory on a half line, at large $N$ and large ’t Hooft coupling, with various boundary conditions that preserve half of the supersymmetry. The solutions are limiting cases of the general solutions with the same symmetries constructed in 2007 by D’Hoker, Estes and Gutperle. The classification of our solutions matches exactly with the general classification of boundary conditions for D3-branes ending on 5-branes by Gaiotto and Witten. We use the gravity duals to compute the one-point functions of some chiral operators in the $\mathcal{N}=4$ SYM theory on a half line at strong coupling, and we find that they do not match with the expectation values of the same operators with the same boundary conditions at small ’t Hooft coupling. Our solutions may also be interpreted as the gravity duals of 4D $\mathcal{N}=4$ SYM on ${\mathrm{AdS}}_4$, with various boundary conditions.

We present an infinite class of $2+1$-dimensional field theories which, after coupling to semiholographic fermions, exhibit strange metallic behavior in a suitable large $N$ limit. These theories describe lattices of hypermultiplet defects interacting with parity-preserving supersymmetric Chern-Simons theories with $U(N)\times U(N)$ gauge groups at levels $\pm k$. They have dual anti-de Sitter (AdS) gravity descriptions in terms of lattices of probe M2-branes in ${\mathrm{AdS}}_4\times S^7/Z_k$ (for $N\gg 1$, $N\gg k^5$) or probe D2-branes in ${\mathrm{AdS}}_4\times C{P}^3$ (for $N\gg k\gg 1$, $N\ll k^5$). We discuss several challenges one faces in maintaining the success of these models at finite $N$, including backreaction of the probes in the gravity solutions and radiative corrections in the weakly coupled field theory limit.

We construct complete sets of (open and closed string) covariant coherent state and mass eigenstate vertex operators in bosonic string theory. This construction can be used to study the evolution of fundamental cosmic strings as predicted by string theory, and is expected to serve as a self-contained prototype toy model on which realistic cosmic superstring vertex operators can be based. It is also expected to be useful for other applications where massive string vertex operators are of interest. We pay particular attention to all the normalization constants, so that these vertices lead directly to unitary $S$-matrix elements.

We consider soliton creation when there are “twist” degrees of freedom present in the model in addition to those that make up the soliton. Specifically, we consider a deformed O(3) sigma model in $1+1$ dimensions, which reduces to the sine-Gordon model in the zero twist sector. We study the scattering of two or more breather solutions as a function of twist, and find soliton creation for a range of parameters. We speculate on the application of these ideas, in particular, on the possible role of magnetic helicity, to the production of magnetic monopoles, and the violation of baryon number in nuclear scattering experiments.

We establish a mapping between fractional and noncommutative spacetimes in configuration space. Depending on the scale at which the relation is considered, there arise two possibilities. For a fractional spacetime with log-oscillatory measure, the effective measure near the fundamental scale determining the log-period coincides with the nonrotation-invariant but cyclicity-preserving measure of $\kappa$-Minkowski spacetime. At scales larger than the log-period, the fractional measure is averaged and becomes a power law with real exponent. This can be also regarded as the cyclicity-inducing measure in a noncommutative spacetime defined by a certain nonlinear algebra of the coordinates, which interpolates between $\kappa$-Minkowski and canonical spacetime. These results are based upon a braiding formula valid for any nonlinear algebra which can be mapped onto the Heisenberg algebra.

The generalized harmonic equations of general relativity are written in $3+1$ form. The result is a system of partial differential equations with first-order time and second-order space derivatives for the spatial metric, extrinsic curvature, lapse function and shift vector, plus fields that represent the time derivatives of the lapse and shift. This allows for a direct comparison between the generalized harmonic and the Arnowitt-Deser-Misner formulations. The $3+1$ generalized harmonic equations are also written in terms of conformal variables and compared to the Baumgarte-Shapiro-Shibata-Nakamura equations with moving puncture gauge conditions.

We discuss a geometrical method to define a preferred reference frame for precessing binary systems and the gravitational waves they emit. This minimal-rotation frame is aligned with the angular-momentum axis and fixes the rotation about that axis up to a constant angle, resulting in an essentially invariant frame. Gravitational waveforms decomposed in this frame are similarly invariant under rotations of the inertial frame and exhibit relatively smoothly varying phase. By contrast, earlier prescriptions for radiation-aligned frames induce extraneous features in the gravitational-wave phase which depend on the orientation of the inertial frame, leading to fluctuations in the frequency that may compound to many gravitational-wave cycles. We explore a simplified description of post-Newtonian approximations for precessing systems using the minimal-rotation frame, and describe the construction of analytical/numerical hybrid waveforms for such systems.

Von Mises’ nonlinear second-order wave equation for the velocity potential in the case of an irrotational, compressible and barotropic classical perfect fluid is connected to the analog gravity formalism. It is shown that while the standard acoustic metric, built on a certain background, remains central in the higher-order perturbative scheme, at full nonlinear level it plays a less relevant role. Possible applications both for simulations and experiments are discussed.

We compute the entanglement entropy associated to the Hawking emission of a ($1+1$)-dimensional acoustic black hole in a Bose-Einstein condensate. We use the brick wall model proposed by ’t Hooft, adapted to the momentum space, in order to tackle the case when high frequency dispersion is taken in account. As expected, we find that in the hydrodynamic limit the entropy only depends on the size of the box in the near-horizon region, as for gravitational ($1+1$)-dimensional black holes. When dispersion effects are considered, we find a correction that depends on the square of the size of the near-horizon region measured in units of healing length, very similar to the universal correction to the entropy found in the case of spin-$1/2$ Heisenberg XX chains.

We present some arguments suggesting that the mismatch between Bekenstein-Hawking entropy and the entropy of entanglement for vector fields is due to the same gauge configurations that saturate the contact term in topological susceptibility in QCD. In both cases, the extra term with the “wrong sign” is due to distinct topological sectors in gauge theories. This extra term has a nondispersive nature, cannot be restored from the conventional spectral function through dispersion relations, and cannot be associated with any physical propagating degrees of freedom. We make a few comments on some of the profound consequences of our findings. In particular, we speculate that the source of the observed dark energy may also be related to the same type of gauge configurations that are responsible for the mismatch between black hole entropy and the entropy of entanglement in the presence of a causal horizon.

We present a semi-analytic prescription to obtain gravitational wave (GW) phasing for spinning compact binaries in inspiraling eccentric orbits, while restricting the spin effects to the leading order spin-orbit coupling. We demonstrate that only the radial part of the orbital dynamics is amenable for a Keplerian-type solution that is compatible with the standard post-Newtonian (PN) accurate quasi-Keplerian parametrization for nonspinning compact binaries. We also derive PN-accurate equations governing the evolution of the Eulerian angles that are crucial to obtain temporally evolving GW polarization states and compute the associated fully 1PN accurate amplitude corrected GW polarization states. We show that it is not possible to obtain a Keplerian-type parametric solution for the angular part of the above dynamics in a noninertial frame that follows the precessing orbital plane [N. J. Cornish and J. S. Key, Phys. Rev. D 82, 044028 (2010)]. Further, we point out certain undesirable features present in their approach for doing GW phasing, like the use of precessing polarization vectors to construct the polarization states.

We revisit the scenario of small-mass-ratio ($q$) black hole binaries; performing new, more accurate, simulations of mass ratios 10:1 and 100:1 for initially nonspinning black holes. We propose fitting functions for the trajectories of the two black holes as a function of time and mass ratio (in the range $1/100\le q\le 1/10$) that combine aspects of post-Newtonian trajectories at smaller orbital frequencies and plunging geodesics at larger frequencies. We then use these trajectories to compute waveforms via black hole perturbation theory. Using the advanced LIGO noise curve, we see a match of $\sim 99.5\%$ for the leading $(\ell ,m)=(2,2)$ mode between the numerical relativity and perturbative waveforms. Nonleading modes have similarly high matches. We thus prove the feasibility of efficiently generating a bank of gravitational waveforms in the intermediate-mass-ratio regime using only a sparse set of full numerical simulations.

In the present paper, the leading-order post-Newtonian spin-orbit and spin(1)-spin(2) radiation-reaction Hamiltonians are calculated. We utilize the canonical formalism of Arnowitt, Deser, and Misner (ADM), which has shown to be valuable for this kind of calculation. The results are valid for arbitrary many objects. The energy loss is then computed and compared to well-known results for the energy flux as a check.

Residual late-time dark matter particle annihilations during and after big-bang nucleosynthesis may alter the predicted cosmological abundances of the light elements. Within the constrained minimal supersymmetric extension of the standard model with a neutralino as the lightest supersymmetric particle, we find negligible effects on the abundances of deuterium, ${}^3\mathrm{He}$, ${}^4\mathrm{He}$, and ${}^7\mathrm{Li}$ predicted by homogeneous big-bang nucleosynthesis, but potentially a large enhancement in the predicted abundance of ${}^6\mathrm{Li}$. This enhancement may be as much as 2 orders of magnitude in the focus-point WMAP strip and in the coannihilation and funnel regions for large $\tan \beta$ for small $m_{1/2}$, and the effect is still significant at large $m_{1/2}$. However, the potential ${}^6\mathrm{Li}$ enhancement is negligible in the part of the coannihilation strip for $\tan \beta =10$ that survives the latest LHC constraints. A similar enhancement of the ${}^6\mathrm{Li}$ abundance may also be found in a model with common, nonuniversal Higgs masses (the NUHM1).

We study a phenomenological dark energy model which is rooted in the Veneziano ghost of QCD. In this dark energy model, the energy density of dark energy is proportional to Hubble parameter and the proportional coefficient is of the order ${\Lambda }_{\mathrm{QCD}}^3$, where ${\Lambda }_{\mathrm{QCD}}$ is the mass scale of QCD. The universe has a de Sitter phase at late time and begins to accelerate at redshift around $z_{\mathrm{acc}}\sim 0.6$. We fit this model and give the constraints on model parameters, with current observational data including Type Ia supernovea, baryon acoustic oscillation, cosmic microwave background, big bang nucleosynthesis, and Hubble parameter data. We also study the cosmological evolution of the dark energy with interaction with cold dark matter.

C-theory provides a unified framework to study metric, metric-affine and more general theories of gravity. In the vacuum weak-field limit of these theories, the parameterized post-Newtonian parameters $\beta$ and $\gamma$ can differ from their general relativistic values. However, there are several classes of models featuring long-distance modifications of gravity but nevertheless passing the Solar System tests. Here it is shown how compute the parameterized post-Newtonian parameters in C-theories and also in nonminimally coupled curvature theories, correcting previous results in the literature for the latter.

Polarization of light rotates in a gravitational field. The accrued phase is operationally meaningful only with respect to a local polarization basis. In stationary space-times, we construct local reference frames that allow us to isolate the Machian gravimagnetic effect from the geodetic (mass) contribution to the rotation. The Machian effect is supplemented by the geometric term that arises from the choice of standard polarizations. The phase accrued along a close trajectory is gauge-independent and is zero in the Schwarzschild space-time. The geometric term may give a dominant contribution to the phase. We calculate polarization rotation for several trajectories and find it to be more significant than is usually believed, pointing to its possible role as a future gravity probe.