We study the corrections to the galaxy three-point correlation function induced by weak lensing magnification due to the matter distribution along the line of sight. We consistently derive all the correction terms arising up to second order in perturbation theory and provide analytic expressions as well as order-of-magnitude estimates for their relative importance. The magnification contributions depend on the geometry of the projected triangle on the sky plane and scale with different powers of the number count slope and redshift of the galaxy sample considered. We evaluate all terms numerically and show that, depending on the triangle configuration as well as the galaxy sample considered, weak lensing can in general significantly contribute to and alter the three-point correlation function observed through galaxy and quasar catalogs.

We have studied the total cross section, $Q^2$, momentum and angular distributions for pions in the $\nu (\overline{\nu })$ induced ${\pi }^0$ production from nucleons. The calculations have been done for the weak production induced by the neutral current in the standard model and the electromagnetic production induced by neutrino magnetic moment. It has been found that with the present experimental limits on the muon neutrino magnetic moment ${\mu }_{{\nu }_{\mu }}$, the electromagnetic contribution to the cross section for the ${\pi }^0$ production is small. The neutrino induced neutral current production of ${\pi }^0$, while giving an alternative method to study the magnetic moment of neutrino ${\mu }_{{\nu }_{\mu }}$, does not provide any improvement over the present experimental limit on ${\mu }_{{\nu }_{\mu }}$ from the observation of this process in future experiments at T2K and $\mathrm{NO}\nu \mathrm{A}$.

Taking the MSSM as an effective low-energy theory, with a cutoff scale of a few TeV can make significant modifications to the predictions concerning the Higgs and stop sectors. We investigate the consequences of such a scenario for electroweak baryogenesis. We find that the window for MSSM baryogenesis is extended and, most important, can be made significantly more natural. Specifically, it is possible to have one stop lighter than the top and the other significantly lighter than TeV simultaneously with the Higgs mass above the LEP bound. In addition, various aspects concerning $CP$ violation are affected. Most notably, it is possible to have dynamical phases in the bubble walls at tree level, providing $CP$ violating sources for standard model fermions.

We study the single transverse-spin asymmetry for open charm production in the semi-inclusive lepton-hadron deep inelastic scattering. We calculate the asymmetry in terms of the QCD collinear factorization approach for $D$ mesons at high enough $P_{h\perp }$ and find that the asymmetry is proportional to the twist-three trigluon correlation function in the proton. With a simple model for the trigluon correlation function, we estimate the asymmetry for both COMPASS and eRHIC kinematics and discuss the possibilities of extracting the trigluon correlation function in these experiments.

The propagation of field disturbances is examined in the context of the effective Yang-Mills Lagrangian, which is intended to be applied to QCD systems. It is shown that birefringence phenomena can occur in such systems provided some restrictive conditions, as causality, are fulfilled. Possible applications to phenomenology are addressed.

Jet cross sections were measured in charged-current deep inelastic $e^{\pm }p$ scattering at high boson virtualities $Q^2$ with the ZEUS detector at HERA II using an integrated luminosity of $0.36{\mathrm{fb}}^{-1}$. Differential cross sections are presented for inclusive-jet production as functions of $Q^2$, Bjorken $x$ and the jet transverse energy and pseudorapidity. The dijet invariant mass cross section is also presented. Observation of three- and four-jet events in charged-current $e^{\pm }p$ processes is reported for the first time. The predictions of next-to-leading-order (NLO) QCD calculations are compared to the measurements. The measured inclusive-jet cross sections are well described in shape and normalization by the NLO predictions. The data have the potential to constrain the $u$ and $d$ valence-quark distributions in the proton if included as input to global fits.

Single charged pion production in charged-current muon neutrino interactions with carbon is studied using data collected in the K2K long-baseline neutrino experiment. The mean energy of the incident muon neutrinos is 1.3 GeV. The data used in this analysis are mainly from a fully active scintillator detector, SciBar. The cross section for single ${\pi }^{+}$ production in the resonance region ($W<2\mathrm{GeV}/c^2$) relative to the charged-current quasielastic cross section is found to be ${0.734}_{-0.153}^{+0.140}$. The energy-dependent cross section ratio is also measured. The results are consistent with a previous experiment and the prediction of our model.

Important classes of null geodesics and hidden symmetries in the Sen black hole are investigated. First, we obtain the principal null geodesics and circular photon orbits. Then, an irreducible rank-two Killing tensor and a conformal Killing tensor are derived, which represent the hidden symmetries. Analyzing the properties of Killing tensors, we clarify why the Hamilton-Jacobi and wave equations are separable in this spacetime. We also investigate the gravitational capture of photons by the Sen black hole and compare the result with those by the various charged/rotating black holes and naked singularities in the Kerr-Newman family. For these black holes and naked singularities, we show the capture regions in a two dimensional impact parameter space (or equivalently the “shadows” observed at infinity) to form a variety of shapes such as the disk, circle, dot, arc, and their combinations.

In this paper it is shown that in Brans-Dicke theory, if one considers a nonminimal coupling between the matter and the scalar field, it can give rise to a late time accelerated expansion for the Universe preceded by a decelerated expansion for very high values of the Brans-Dicke parameter $\omega$.

In this clarifying paper we discuss the late decay of an Affleck-Dine condensate by providing a no-go theorem that attributes to conserved global charges which are identified by the net particle number in fields which are included in the flat direction(s). For a rotating condensate, this implies that (1) the net baryon/lepton number density stored in the condensate is always conserved, and (2) the total particle number density in the condensate cannot decrease. This reiterates that, irrespective of possible nonperturbative particle production due to $D$ terms in a multiple flat direction case, the prime decay mode of an Affleck-Dine condensate will be perturbative as originally envisaged. As a result, cosmological consequences of flat directions such as delayed thermalization as a novel solution to the gravitino overproduction problem will remain virtually intact.

The standard inflationary version of the origin of the cosmic structure as the result of the quantum fluctuations during the early universe is less than fully satisfactory as has been argued in [A. Perez, H. Sahlmann, and D. Sudarsky, Classical Quantum Gravity 23, 2317 (2006).]. A proposal is made there of a way to address the shortcomings by invoking a process similar to the collapse of the quantum-mechanical wave function of the various modes of the inflaton field. This in turn was inspired by the ideas of R. Penrose about the role that quantum gravity might play in bringing about such a breakdown of the standard unitary evolution of quantum mechanics. In this paper we study in some detail the two schemes of collapse considered in the original work together with an alternative scheme, which can be considered as “more natural” than the former two. The new scheme assumes that the collapse follows the correlations indicated in the Wigner functional of the initial state. We end with considerations regarding the degree to which the various schemes can be expected to produce a spectrum that resembles the observed one.

We studied a constraint on the primordial helium abundance $Y_p$ from current and future observations of CMB. Using the currently available data from WMAP, ACBAR, CBI, and BOOMERANG, we obtained the constraint as $Y_p={0.25}_{-0.07}^{+0.10}$ at 68% confidence level. We also provide a forecast for the Planck experiment using the Markov chain Monte Carlo approach. In addition to forecasting the constraint on $Y_p$, we investigate how assumptions for $Y_p$ affect constraints on the other cosmological parameters.

We study the effect of modifications to general relativity on large-scale weak lensing observables. In particular, we consider three modified gravity scenarios: $f(R)$ gravity, the Dvali-Gabadadze-Porrati model, and tensor-vector-scalar theory. Weak lensing is sensitive to the growth of structure and the relation between matter and gravitational potentials, both of which will in general be affected by modified gravity. Restricting ourselves to linear scales, we compare the predictions for galaxy-shear and shear-shear correlations of each modified gravity cosmology to those of an effective dark energy cosmology with the same expansion history. In this way, the effects of modified gravity on the growth of perturbations are separated from the expansion history. We also propose a test which isolates the matter-potential relation from the growth factor and matter power spectrum. For all three modified gravity models, the predictions for galaxy and shear correlations will be discernible from those of dark energy with very high significance in future weak lensing surveys. Furthermore, each model predicts a measurably distinct scale dependence and redshift evolution of galaxy and shear correlations, which can be traced back to the physical foundations of each model. We show that the signal-to-noise for detecting signatures of modified gravity is much higher for weak lensing observables as compared to the integrated Sachs-Wolfe effect, measured via the galaxy-cosmic microwave background cross-correlation.

We report on the methods and results of the first dedicated search for gravitational waves emitted during the inspiral of compact binaries with spinning component bodies. We analyze 788 hours of data collected during the third science run (S3) of the LIGO detectors. We searched for binary systems using a detection template family specially designed to capture the effects of the spin-induced precession of the orbital plane. We present details of the techniques developed to enable this search for spin-modulated gravitational waves, highlighting the differences between this and other recent searches for binaries with nonspinning components. The template bank we employed was found to yield high matches with our spin-modulated target waveform for binaries with masses in the asymmetric range $1.0M_{\odot }<m_1<3.0M_{\odot }$ and $12.0M_{\odot }<m_2<20.0M_{\odot }$ which is where we would expect the spin of the binary’s components to have a significant effect. We find that our search of S3 LIGO data has good sensitivity to binaries in the Milky Way and to a small fraction of binaries in M31 and M33 with masses in the range $1.0M_{\odot }<m_1$, $m_2<20.0M_{\odot }$. No gravitational wave signals were identified during this search. Assuming a binary population with spinning components and Gaussian distribution of masses representing a prototypical neutron star–black hole system with $m_1\simeq 1.35M_{\odot }$ and $m_2\simeq 5M_{\odot }$, we calculate the 90%-confidence upper limit on the rate of coalescence of these systems to be $15.9{\mathrm{yr}}^{-1}{\mathrm{L}}_{10}^{-1}$, where ${\mathrm{L}}_{10}$ is ${10}^{10}$ times the blue light luminosity of the Sun.

We explore possible signals of CPT violation in neutrinos in the complete three-flavor framework. Employing a systematic expansion in small parameters, we analytically estimate the CPT violating contributions to the survival probabilities of ${\nu }_{\mu }$, ${\overline{\nu }}_{\mu }$, ${\nu }_e$ and, ${\overline{\nu }}_e$. The results indicate that, in spite of the large number of CPT violating parameters, only a small number of combinations are relevant for oscillation experiments. We identify the combinations that can be constrained at the long baseline experiments, and show that their contribution to the neutrino Hamiltonian can be bounded to $\lesssim {10}^{-23}\mathrm{GeV}$, by considering the NOvA experiment for the muon sector, and neutrino factories for the electron sector. This formalism also allows us to translate the bounds on the parameters describing non-standard interactions of neutrinos into the bounds on CPT violating quantities.

We present an update of the theoretical predictions for the cross section of top-quark pair production at Tevatron and LHC. In particular, we employ improvements due to soft-gluon resummation at next-to-next-to-leading logarithmic accuracy. We expand the resummed results and derive analytical finite-order cross sections through next-to-next-to-leading order which are exact in all logarithmically enhanced terms near threshold. These results are the best present estimates for the top-quark pair production cross section. We investigate the scale dependence as well as the sensitivity on the parton luminosities.

We develop a formalism to evaluate the Sivers function. The approach is well suited for calculations which use constituent quark models to describe the structure of the nucleon. A nonrelativistic reduction of the scheme is performed and applied to the Isgur-Karl model of hadron structure. The results obtained are consistent with a sizable Sivers effect and the signs for the $u$ and $d$ flavor contributions turn out to be opposite. This pattern is in agreement with the one found analyzing, in the same model, the impact parameter dependent generalized parton distributions. The Burkardt sum rule turns out to be fulfilled to a large extent. We estimate the QCD evolution of our results from the momentum scale of the model to the experimental one and obtain reasonable agreement with the available data.

Neutrino masses can be generated by fermion triplets with TeV-scale mass, that would manifest at LHC as production of two leptons together with two heavy standard model (SM) vectors or Higgs, giving rise to final states such as $2\ell +4j$ (that can violate lepton number and/or lepton flavor) or $\ell +4j+{\mathrm{E̸}}_T$. We devise cuts to suppress the SM backgrounds to these signatures. Furthermore, for most of the mass range suggested by neutrino data, triplet decays are detectably displaced from the production point, allowing to infer the neutrino mass parameters. We compare with LHC signals of type-I and type-II seesaw.

The results of the second phase of the Super-Kamiokande solar neutrino measurement are presented and compared to the first phase. The solar neutrino flux spectrum and time variation as well as oscillation results are statistically consistent with the first phase and do not show spectral distortion. The time-dependent flux measurement of the combined first and second phases coincides with the full period of solar cycle 23 and shows no correlation with solar activity. The measured ${}^8\mathrm{B}$ total flux is $(2.38\pm 0.05(\mathrm{stat}.{)}_{-0.15}^{+0.16}(\mathrm{sys}.))\times {10}^6{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}$ and the day-night difference is found to be $(-6.3\pm 4.2(\mathrm{stat}.)\pm 3.7(\mathrm{sys}.))\%$. There is no evidence of systematic tendencies between the first and second phases.

We present the Bjorken integral extracted from Jefferson Lab experiment EG1b for $0.05<Q^2<2.92{\mathrm{GeV}}^2$. The integral is fit to extract the twist-4 element $f_2^{p-n}$ which appears to be relatively large and negative. Systematic studies of this higher twist analysis establish its legitimacy at $Q^2$ around $1{\mathrm{GeV}}^2$. We also performed an isospin decomposition of the generalized forward spin polarizability ${\gamma }_0$. Although its isovector part provides a reliable test of the calculation techniques of chiral perturbation theory, our data disagree with the calculations.