We investigate the potential to observe double parton scattering at the Large Hadron Collider in $pp\to Wb\overline{b}X\to \ell \nu b\overline{b}X$ at 7 TeV. Our analysis tests the efficacy of several kinematic variables in isolating the double parton process of interest from the single parton process and relevant backgrounds for the first $10{\mathrm{fb}}^{-1}$ of integrated luminosity. These variables are constructed to expose the independent nature of the two subprocesses in double parton scattering, $pp\to \ell \nu X$ and $pp\to b\overline{b}X$. We use next-to-leading order perturbative predictions for the double parton and single parton scattering components of $Wb\overline{b}$ and for the pertinent backgrounds. The next-to-leading order contributions are important for a proper description of some of the observables we compute. We find that the double parton process can be identified and measured with significance $S/\sqrt{B}\sim 10$, provided the double parton scattering effective cross section ${\sigma }_{\mathrm{eff}}\sim 12\mathrm{mb}$.

We explore the thermodynamics and phase structure of the Polyakov loop-extended two-flavor chiral quark-meson (PQM) model beyond the mean-field approximation at imaginary chemical potential. Our approach is based on the functional renormalization group (FRG) method. At finite temperature and imaginary chemical potential, we solve the renormalization group flow equation for a scale-dependent thermodynamic potential in the presence of the gluonic background field. We determine the behavior of the order parameters of the PQM model in the FRG approach and compute the phase diagram. We compare our FRG results with those obtained in the mean-field approximation at imaginary chemical potential.

We show how the integrators used for the molecular dynamics step of the Hybrid Monte Carlo algorithm can be further improved. These integrators not only approximately conserve some Hamiltonian $H$ but conserve exactly a nearby shadow Hamiltonian $\tilde{H}$. This property allows for a new tuning method of the molecular dynamics integrator and also allows for a new class of integrators (force-gradient integrators) which is expected to reduce significantly the computational cost of future large-scale gauge field ensemble generation.

A measurement of the top-quark mass is presented using Tevatron data from proton-antiproton collisions at center-of-mass energy $\sqrt{s}=1.96\mathrm{TeV}$ collected with the CDF II detector. Events are selected from a sample of candidates for production of $t\overline{t}$ pairs that decay into the $\mathrm{\text{lepton}}+\mathrm{\text{jets}}$ channel. The top-quark mass is measured with an unbinned maximum likelihood method where the event probability density functions are calculated using signal and background matrix elements, as well as a set of parametrized jet-to-parton transfer functions. The likelihood function is maximized with respect to the top-quark mass, the signal fraction in the sample, and a correction to the jet energy scale (JES) calibration of the calorimeter jets. The simultaneous measurement of the JES correction (${\Delta }_{\mathrm{JES}}$) amounts to an additional in situ jet energy calibration based on the known mass of the hadronically decaying $W$ boson. Using the data sample of 578 $\mathrm{\text{lepton}}+\mathrm{\text{jets}}$ candidate events, corresponding to $3.2{\mathrm{fb}}^{-1}$ of integrated luminosity, the top-quark mass is measured to be $m_t=172.4\pm 1.4(\mathrm{stat}+{\Delta }_{\mathrm{JES}})\pm 1.3(\mathrm{syst})\mathrm{GeV}/c^2$.

We consider the behavior of macroscopic bodies within the framework of relative locality [G. Amelino-Camelia, L. Freidel, J. Kowalski-Glikman, and L. Smolin, arXiv:1101.0931]. This is a recent proposal for Planck scale modifications of the relativistic dynamics of particles which are described as arising from deformations in the geometry of momentum space. We consider and resolve a common objection against such proposals, which is that, even if the corrections are small for elementary particles in current experiments, they are huge when applied to composite systems such as soccer balls, planets, and stars, with energies $E_{\mathrm{macro}}$ much larger than $M_P$. We show that this soccer ball problem does not arise within the framework of relative locality because the nonlinear effects for the dynamics of a composite system with $N$ elementary particles appear at most of order $E_{\mathrm{macro}}/N·M_P$.

We use AdS/QCD duality to compute the finite temperature Green’s function $G(\omega ,k;T)$ of the shear operator $T_{12}$ for all $\omega$, $k$ in hot Yang-Mills theory in the strongly coupled domain. The goal is to assess how the existence of scales like the transition temperature and glueball masses affect the correlator computed in the scalefree conformal $\mathcal{N}=4$ supersymmetric Yang-Mills theory. We observe sizeable effects for $T$ close to $T_c$ which rapidly disappear with increasing $T$. Quantitative agreement of these predictions with future lattice Monte Carlo data would suggest that QCD matter in this temperature range is strongly interacting.

The conformal compensator formalism is a convenient and versatile representation of supergravity (SUGRA) obtained by gauge-fixing conformal SUGRA. Unfortunately, practical calculations often require cumbersome manipulations of component field terms involving the full gravity multiplet. In this paper, we derive an alternative gauge fixing for conformal SUGRA which decouples these gravity complications from SUGRA computations. This yields a simplified tree-level action for the matter fields in SUGRA which can be expressed compactly in terms of superfields and a modified conformal compensator. Phenomenologically relevant quantities such as the scalar potential and fermion mass matrix are then straightforwardly obtained by expanding the action in superspace.

The draining bathtub flow, a cornerstone in the theory of acoustic black holes, is here extended to the case of exact solutions for compressible nonviscous flows characterized by a polytropic equation of state. Investigating the analytical configurations obtained for selected values of the polytropic index, it is found that each of them becomes nonphysical at the so called limiting circle. By studying the null geodesics structure of the corresponding acoustic line elements, it is shown that such a geometrical locus coincides with the acoustic event horizon. This region is characterized also by an infinite value of space-time curvature, so the acoustic analogy breaks down there. Possible applications for artificial and natural vortices are finally discussed.

We compute and analyze the gravitational waveform emitted to future null infinity by a system of two black holes in the large-mass-ratio limit. We consider the transition from the quasiadiabatic inspiral to plunge, merger, and ringdown. The relative dynamics is driven by a leading order in the mass ratio, 5PN-resummed, effective-one-body (EOB), analytic-radiation reaction. To compute the waveforms, we solve the Regge-Wheeler-Zerilli equations in the time-domain on a spacelike foliation, which coincides with the standard Schwarzschild foliation in the region including the motion of the small black hole, and is globally hyperboloidal, allowing us to include future null infinity in the computational domain by compactification. This method is called the hyperboloidal layer method, and is discussed here for the first time in a study of the gravitational radiation emitted by black hole binaries. We consider binaries characterized by five mass ratios, $\nu ={10}^{-2,-3,-4,-5,-6}$, that are primary targets of space-based or third-generation gravitational wave detectors. We show significative phase differences between finite-radius and null-infinity waveforms. We test, in our context, the reliability of the extrapolation procedure routinely applied to numerical relativity waveforms. We present an updated calculation of the final and maximum gravitational recoil imparted to the merger remnant by the gravitational wave emission, $v_{\mathrm{kick}}^{\mathrm{end}}/(c{\nu }^2)=0.04474\pm 0.00007$ and $v_{\mathrm{kick}}^{\max }/(c{\nu }^2)=0.05248\pm 0.00008$. As a self-consistency test of the method, we show an excellent fractional agreement (even during the plunge) between the 5PN EOB-resummed mechanical angular momentum loss and the gravitational wave angular momentum flux computed at null infinity. New results concerning the radiation emitted from unstable circular orbits are also presented. The high accuracy waveforms computed here could be considered for the construction of template banks or for calibrating analytic models such as the effective-one-body model.

We consider a gravitating spherically symmetric configuration consisting of a scalar field nonminimally coupled to ordinary matter in the form of a perfect fluid. For this system we find static, regular, asymptotically flat solutions for both relativistic and nonrelativistic cases. It is shown that the presence of the nonminimal interaction leads to substantial changes both in the radial matter distribution of the star and in the star’s total mass. A simple stability test indicates that, for the choice of parameters used in the paper, the solutions are unstable.

Hořava-Lifshitz gravity is an attempt to construct a renormalizable theory of gravity by breaking the Lorentz invariance of the gravitational action at high energies. The underlying principle is that Lorentz invariance is an approximate symmetry and its violation by gravitational phenomena is somehow hidden to present limits of observational precision. Here I point out that a simple modification of the low-energy limit of Hořava-Lifshitz gravity in its nonprojectable form can effectively camouflage the presence of a preferred frame in regions where the Newtonian gravitational field gradient is higher than $c{H}_0$; this modification results in the phenomenology of modified Newtonian dynamics (MOND) at lower accelerations. As a relativistic theory of MOND, this modified Hořava-Lifshitz theory presents several advantages over its predecessors.

Using large-scale real-time lattice simulations, we calculate the baryon asymmetry generated at a fast, cold electroweak symmetry breaking transition. $CP$-violation is provided by the leading effective bosonic term resulting from integrating out the fermions in the Minimal Standard Model at zero-temperature, and performing a covariant gradient expansion [A. Hernandez, T. Konstandin, and M. G. Schmidt, Nucl. Phys. B812, 290 (2009).]. This is an extension of the work presented in [A. Tranberg, A. Hernandez, T. Konstandin, and M. G. Schmidt, Phys. Lett. B 690, 207 (2010).]. The numerical implementation is described in detail, and we address issues specifically related to using this $CP$-violating term in the context of Cold Electroweak Baryogenesis.

We study some properties of the dark degeneracy, which is the fact that what we measure in gravitational experiments is the energy-momentum tensor of the total dark sector, and any split into components (as in dark matter and dark energy) is arbitrary. In fact, just one dark fluid is necessary to obtain exactly the same cosmological and astrophysical phenomenology as the $\Lambda \mathrm{CDM}$ model. We work explicitly the first-order perturbation theory and show that beyond the linear order the dark degeneracy is preserved under some general assumptions. Then we construct the dark fluid from a collection of interacting fluids. Finally, we try to break the degeneracy with a general class of couplings to baryonic matter. Nonetheless, we show that these interactions can also be understood in the context of the $\Lambda \mathrm{CDM}$ model as between dark matter and baryons. For this last investigation we choose two independent parametrizations for the interactions, one inspired by electromagnetism and the other by chameleon theories. Then, we constrain them with a joint analysis of CMB and supernovae observational data.

For a single scalar field with unit sound speed minimally coupled to Einstein gravity, there are exactly three distinct cosmological solutions which produce a scale invariant spectrum of curvature perturbations in a dynamical attractor background, assuming vacuum initial conditions: slow-roll inflation; a slowly contracting adiabatic ekpyrotic phase, described by a rapidly-varying equation of state; and an adiabatic ekpyrotic phase on a slowly expanding background. Of these three, only inflation remains weakly coupled over a wide range of modes, while the other scenarios can produce at most 12 e-folds of scale invariant and Gaussian modes. In this paper, we investigate how allowing the speed of sound of fluctuations to evolve in time affects this classification. While in the presence of a variable sound speed there are many more scenarios which are scale invariant at the level of the two-point function, they generically suffer from strong coupling problems similar to those in the canonical case. There is, however, an exceptional case with superluminal sound speed, which suppresses non-Gaussianities and somewhat alleviates strong coupling issues. We focus on a particular realization of this limit and show these scenarios are constrained and only able to produce at most 28 e-folds of scale invariant and Gaussian perturbations. A similar bound should hold more generally—the condition results from the combined requirements of matching the observed amplitude of curvature perturbations, demanding that the Hubble parameter remain sub-Planckian and keeping non-Gaussianities under control. We therefore conclude that inflation remains the unique cosmological scenario, assuming a single degree of freedom on an attractor background, capable of producing arbitrarily many scale invariant modes while remaining weakly coupled. Alternative mechanisms must inevitably be unstable or rely on multiple degrees of freedom.

We present analytic solutions to a class of cosmological models described by a canonical scalar field minimally coupled to gravity and experiencing self interactions through a hyperbolic potential. Using models and methods inspired by 2T-physics, we show how analytic solutions can be obtained in flat/open/closed Friedmann-Robertson-Walker universes. Among the analytic solutions, there are many interesting geodesically complete cyclic solutions in which the universe bounces at either zero or finite sizes. When geodesic completeness is imposed, it restricts models and their parameters to a certain parameter subspace, including some quantization conditions on initial conditions in the case of zero-size bounces, but no conditions on initial conditions for the case of finite-size bounces. We will explain the theoretical origin of our model from the point of view of 2T-gravity as well as from the point of view of the colliding branes scenario in the context of M-theory. We will indicate how to associate solutions of the quantum Wheeler-deWitt equation with our classical analytic solutions, mention some physical aspects of the cyclic solutions, and outline future directions.

The cross-correlation search has been previously applied to map the gravitational wave (GW) stochastic background in the sky and also to target GW from rotating neutron stars/pulsars. Here we investigate how the cross-correlation method can be used to target a small region in the sky spanning at most a few pixels, where a pixel in the sky is determined by the diffraction limit which depends on the (i) baseline joining a pair of detectors and (ii) detector bandwidth. Here as one of the promising targets, we consider the Virgo cluster—a “hot spot” spanning few pixels—which could contain, as estimates suggest $\sim {10}^{11}$ neutron stars, of which a small fraction would continuously emit GW in the bandwidth of the detectors. For the detector baselines, we consider advanced detector pairs among LCGT, LIGO, Virgo, ET, etc. Our results show that sufficient signal to noise can be accumulated with integration times of the order of a year if the ellipticity of neutron stars is larger than ${10}^{-6}$. The results improve for the multibaseline search. This analysis could as well be applied to other likely hot spots in the sky and other possible pairs of detectors.

The pair production of Majorana neutrinos with transit magnetic moments from the annihilation of charged particles in colliding experiments is discussed using the Pauli interaction, through which the neutral neutrinos with magnetic moments can be probed by the photon. The pair of neutrinos with different flavors are produced due to the transit magnetic moment coupling. We discuss the correlations of flavors in pairs produced back-to-back in the center of the mass frame, where the angular distribution peaks at $\theta =\pi /2$ with respect to the beam direction. We demonstrate that the flavor mixing angle can be inferred by measuring the flavor correlation in pairs.

We perform a study of the charged Higgs production from an $SU(3{)}_C\otimes SU(3{)}_L\otimes U(1{)}_X$ model with right-handed neutrinos, postulating a custodial symmetry which reduces the number of free parameters in the scalar potential. We compute the cross sections for charged scalars for typical and new production modes. One of the new $SU(3{)}_L$ neutral gauge bosons, $Z^{\prime }$, affects some production cross sections distinguishing the model from other standard model extensions like, for example, the minimal supersymmetric standard model and general two-Higgs doublets models. The interplay between the Higgs sector of the model and that $Z^{\prime }$ gauge boson enhances substantially all the production rates of the lightest charged Higgs boson, $H_1^{\pm }$, at hadron colliders compared to the MSSM. We found that a large portion of the parameters space can be probed at the LHC running at 14 TeV center-of-mass energy in the associated $pp\to W^{\pm }{H}_1^{\mp }+X$ production channel in the low luminosity run stage of the experiment.