We examine the leading order noncommutative corrections to the differential and total cross sections for $e^{+}{e}^{-}\to q\overline{q}$. After averaging over the Earth’s rotation, the results depend on the latitude for the collider, as well as the direction of the incoming beam. They also depend on the scale and direction of the noncommutativity. Using data from LEP, we exclude regions in the parameter space spanned by the noncommutative scale and angle relative to the Earth’s axis. We also investigate possible implications for phenomenology at the future International Linear Collider.

Light gravitinos, with mass in the eV to MeV range, are well motivated in particle physics, but their status as dark-matter candidates is muddled by early-Universe uncertainties. We investigate how upcoming data from colliders may clarify this picture. Light gravitinos are produced primarily in the decays of the next-to-lightest supersymmetric particle, resulting in spectacular signals, including di-photons, delayed and nonpointing photons, kinked charged tracks, and heavy metastable charged particles. We find that the Tevatron with $20{\mathrm{fb}}^{-1}$ and the 7 TeV LHC with $1{\mathrm{fb}}^{-1}$ may both see evidence for hundreds of light-gravitino events. Remarkably, this collider data is also well suited to distinguish between currently viable light-gravitino scenarios, with striking implications for structure formation, inflation, and other early-Universe cosmology.

We compute the capture rate for dark matter in the Sun for models where the dominant interaction with nuclei is inelastic—the dark matter up-scatters to a nearby dark “partner” state with a small splitting of the order of 100 keV. Such models have been shown to be compatible with DAMA/LIBRA data, as well as data from all other direct detection experiments. The kinematics of inelastic dark matter ensures that the dominant contribution to capture occurs from scattering off of iron. We give a prediction for neutrino rates for current and future neutrino telescopes based on the results from current direct detection experiments. Current bounds from Super-Kamiokande and IceCube-22 significantly constrain these models, assuming annihilations are into two-body standard model final states, such as $W^{+}{W}^{-}$, $t\overline{t}$, $b\overline{b}$, or ${\tau }^{+}{\tau }^{-}$. Annihilations into first and second generation quarks and leptons are generally allowed, as are annihilations into new force carriers which decay dominantly into $e^{+}{e}^{-}$, ${\mu }^{+}{\mu }^{-}$, and ${\pi }^{+}{\pi }^{-}$.

We analyze the so-called pinched weights, that are generally thought to reduce the violation of quark-hadron duality in finite-energy sum rules. After showing how this is not true in general, we explain how to address this question for the left-right correlator and any particular pinched weight, taking advantage of our previous work [1], where the possible high-energy behavior of the left-right spectral function was studied. In particular, we show that the use of pinched weights allows to determine with high accuracy the dimension six and eight contributions in the operator-product expansion, ${\mathcal{O}}_6=(-{4.3}_{-0.7}^{+0.9})\times {10}^{-3}{\mathrm{GeV}}^6$ and ${\mathcal{O}}_8=(-{7.2}_{-5.3}^{+4.2})\times {10}^{-3}{\mathrm{GeV}}^8$.

We analyze a toy model describing an empty spacetime in which the motion of a test mass (and the trajectories of photons) evidence the presence of a continuous and homogeneous distribution of matter; however, since the energy-momentum tensor vanishes, no real matter or energy distribution is present at all. Thus, a hypothetical observer will conclude that he is immersed in some sort of dark matter, even though he has no chance to directly detect it. This suggests yet another possibility of explaining the elusive dark matter as a purely dynamical effect due to the curvature of spacetime.

Starting from a NJL-type model with $N$ fermion species, fermion and difermion condensates and their associated phase structures are considered at nonzero chemical potential $\mu$ and zero temperature in spaces with nontrivial topology of the form $S^1\otimes S^1\otimes S^1$ and $R^2\otimes S^1$. Special attention is devoted to the generation of the superconducting phase. In particular, for the cases of antiperiodic and periodic boundary conditions we have found that the critical curve of the phase transitions between the chiral symmetry breaking and superconducting phases as well as the corresponding condensates and particle densities strongly oscillate versus $\lambda \sim 1/L$, where $L$ is the length of the circumference $S^1$. Moreover, it is shown that at some finite values of $L$ the superconducting phase transition is shifted to smaller values both of $\mu$ and particle density in comparison with the case of $L=\infty$.

We develop a consistent relativistic generalization of collective coordinate quantization of field theory solitons. Our principle of introducing collective coordinates is that the equations of motion of the collective coordinates ensure those of the original field theory. We illustrate this principle with the quantization of spinning degrees of freedom of Skyrmion representing baryons. We calculate the leading relativistic corrections to the static properties of nucleons, and find that the corrections are non-negligible ones of 10% to 20%.

We present the first comparison between numerical relativity (NR) simulations of an eccentric binary black hole system with corresponding post-Newtonian (PN) results. We evolve an equal-mass, nonspinning configuration with an initial eccentricity $e\approx 0.1$ for 21 gravitational wave cycles before merger, and find agreement in the gravitational wave phase with an adiabatic eccentric PN model with 2 PN radiation reaction within 0.1 radians for 10 cycles. The NR and PN phase difference grows to 0.7 radians by 5 cycles before merger. We find that these results can be obtained by expanding the eccentric PN expressions in terms of the frequency-related variable $x=(\omega M{)}^{2/3}$ with $M$ the total mass of the binary. When using instead the mean motion $n=2\pi /P$, where $P$ is the orbital period, the comparison leads to significant disagreements with NR.

We derive and study the equations of motion of the Born-Infeld extension of new massive gravity for globally and asymptotically (anti-)de Sitter spaces, and show that the assumptions of the null-energy condition and holography (that bounds the $c$-function) lead to two simple $c$-functions, one of which is equivalent to the $c$-function of Einstein’s gravity. We also show that, at the fixed point, the $c$-function gives the central charge of the Virasoro algebra and the coefficient of the Weyl anomaly up to a constant.

We have investigated the necessary conditions that prevent phantom inflation from being eternal. Allowing additionally for a nonminimal coupling between the phantom field and gravity, we present the slow-climb requirements, perform an analysis of the fluctuations, and finally we extract the overall conditions that are necessary in order to prevent eternality. Furthermore, we verify our results by solving explicitly the cosmological equations in a simple example of an exponential potential, formulating the classical motion plus the stochastic effect of the fluctuations through Langevin equations. Our analysis shows that phantom inflation can be finite without the need of additional exotic mechanisms.

The usual (Bunch-Davies) Feynman propagator of a massless field is not well defined in an expanding universe due to the presence of infrared divergences. We propose a new propagator which yields IR finite answers to any correlation function. The key point is that in a de Sitter space-time there is an ambiguity in the zero mode of the propagator. This ambiguity can be used to cancel the apparent divergences which arise in some loop calculations in eternally (or semieternally) inflating space-time. We refer to this process as zero-mode modification. The residual ambiguity is fixed by observational measurement.

Helical magnetic fields are injected into the cosmic medium during cosmological baryogenesis and can potentially provide a useful probe of the early universe. We construct a model to study the injection process during a first order phase transition and to determine the power spectra of the injected magnetic field. By Monte Carlo simulations we evaluate the Fourier space symmetric and helical power spectra of the magnetic field at the time the phase transition completes. The spectra are peaked at the scale given by the inverse size of bubbles at percolation and with a comparable width. These injected magnetic fields set the initial conditions for further cosmological magneto-hydrodynamical evolution.

We present the first multifluid analysis of a dense neutron star core with a deconfined color-flavor-locked superconducting quark component. Accounting only for the condensate and (finite temperature) phonons, we make progress by taking over results for superfluid ${}^4\mathrm{He}$. The resultant two-fluid model accounts for a number of additional viscosity coefficients (compared to the Navier-Stokes equations) and we show how they enter the dissipation analysis for an oscillating star. We provide simple estimates for the gravitational-wave driven r-mode instability, demonstrating that the various phonon processes that we consider are not effective damping agents. Even though the results are likely of little direct astrophysical importance (since we consider an overly simplistic stellar model) our analysis represents significant technical progress, laying the foundation for more detailed numerical studies and preparing the ground for the inclusion of additional aspects (in particular associated with kaons) of the problem.

We studied the question of parity breaking in a supersymmetric left-right model, in which the left-right symmetry is broken with Higgs doublets (carrying $B-L=\pm 1$). Unlike the left-right symmetric models with triplet Higgs scalars (carrying $B-L=\pm 2$), in this model it is possible to break parity spontaneously by adding a parity-odd singlet. We then discussed how neutrino mass of type-III seesaw can be invoked in this model by adding extra fermion singlets. We considered simple forms of the mass matrices that are consistent with the unification scheme and demonstrate how they can reproduce the required neutrino mixing matrix. In this model, the baryon asymmetry of the Universe is generated via leptogenesis. The required mass scales in the model are then found to be consistent with the gauge coupling unification.

We investigate the NLO QCD and the $CP$-violation effects in $t\overline{t}{Z}^0$ production at the LHC in the minimal supersymmetric standard model (MSSM). Our calculation shows that the total NLO QCD correction in the framework of the $CP$-conserving MSSM significantly improves the scale uncertainty at the leading order, and the contribution from the pure supersymmetric QCD (pSQCD) correction can exceed $-8\%$ with the restrictions of $90\mathrm{GeV}<p_T^t<120\mathrm{GeV}$ and $120\mathrm{GeV}<p_T^Z<150\mathrm{GeV}$, where $p_T^t$ and $p_T^Z$ are the transverse momenta of the top quark and $Z^0$ gauge boson, respectively. Our numerical results demonstrate that the pure supersymmetric QCD correction generally suppresses the total standard model-like QCD correction in the $CP$-conserving MSSM, and tends to be a constant when either ${\tilde{t}}_1$ or $\tilde{g}$ is heavy enough. We find also that the $CP$-odd asymmetry ${\mathcal{A}}_{\Phi }$ can reach $2.17\times {10}^{-3}$, if the $CP$-phase angle really exists in the coupling of gluino-stop-top.

In light cone gauge, a gauge link at light cone infinity is necessary for transverse momentum-dependent parton distribution to restore the gauge invariance in some specific boundary conditions. We derive such transverse gauge link in a more regular and general method. We find the gauge link at light cone infinity naturally arises from the contribution of the pinched poles: one is from the quark propagator and the other is hidden in the gauge vector field in light cone gauge. Actually, in the amplitude level, we have obtained a more general gauge link over the hypersurface at light cone infinity which is beyond the transverse direction. The difference of such gauge link between semi-inclusive deep inelastic scattering and Drell-Yan processes can also be obtained directly and clearly in our derivation.

In this paper we evaluate the double deeply virtual Compton scattering on nucleons and nuclei in the framework of the color dipole model. Both the effects of quark and the gluon shadowing are taken into account.

I study two-flavor staggered chiral perturbation theory in the light pseudoscalar sector. The pion mass and decay constant are calculated through next-to-leading order in the partially-quenched case. In the limit where the strange quark mass is large compared to the light quark masses and the taste splittings, I show that the SU(2) staggered chiral theory emerges from the SU(3) staggered chiral theory, as expected. Explicit relations between SU(2) and SU(3) low energy constants and taste-violating parameters are given. The results are useful for SU(2) chiral fits to asqtad data and allow one to incorporate effects from varying strange quark masses.

We compare the single inclusive spectra of isolated photons measured at high transverse energy in proton-antiproton collisions at $\sqrt{s}=1.96\mathrm{TeV}$ with next-to-leading-order perturbative QCD predictions with various parametrizations of the parton distribution functions (PDFs). Within the experimental and theoretical uncertainties, the Tevatron data can be reproduced equally well by the recent CTEQ6.6, MSTW08, and NNPDF1.2 PDF sets. We also present the predictions for isolated $\gamma$ spectra in proton-proton collisions at $\sqrt{s}=14\mathrm{TeV}$ for central ($y=0$) and forward ($y=4$) rapidities relevant for LHC experiments. Different proton PDFs result in maximum variations of order $\pm 30\%$ in the expected $E_T^{\gamma }$-differential isolated $\gamma$ cross sections. The inclusion of the isolated photon data in global PDF fits will place extra independent constraints on the gluon density.

Using a sample of $25.9\times {10}^6$ $\psi (2S)$ decays acquired with the CLEO-c detector at the CESR $e^{+}{e}^{-}$ collider, we report branching fractions for the decays ${\chi }_{cJ}\to p\overline{p}{\pi }^0$, $p\overline{p}\eta$, and $p\overline{p}\omega$, with $J=0$, 1, 2. Our results for $\mathcal{B}({\chi }_{cJ}\to p\overline{p}{\pi }^0)$ and $\mathcal{B}({\chi }_{cJ}\to p\overline{p}\eta )$ are consistent with, but more precise than, previous measurements. Furthermore, we include the first measurement of $\mathcal{B}({\chi }_{cJ}\to p\overline{p}\omega )$.