We extract new parton distribution functions (PDFs) of the proton by global analysis of hard scattering data in the general-mass framework of perturbative quantum chromodynamics. Our analysis includes new theoretical developments together with the most recent collider data from deep-inelastic scattering, vector boson production, and single-inclusive jet production. Because of the difficulty in fitting both the D0 Run-II W lepton asymmetry data and some fixed-target DIS data, we present two families of PDFs, CT10 and CT10W, without and with these high-luminosity W lepton asymmetry data included in the global analysis. With both sets of PDFs, we study theoretical predictions and uncertainties for a diverse selection of processes at the Fermilab Tevatron and the CERN Large Hadron Collider.

We present next-to-next-to-leading order (NNLO) parton distribution functions (PDFs) from the CTEQ-TEA group. The CT10NNLO PDF fit is based on essentially the same global data sets used in the CT10 and CT10W NLO PDF analyses. After exploring the goodness of the fits to the HERA combined data and the Tevatron jet data, we present various predictions at NNLO accuracy for both existing and forthcoming precision measurements from the CERN Large Hadron Collider. The range of variations in the gluon distribution introduced by correlated systematic effects in inclusive jet production is also examined.

We examine the dependence of parton distribution functions (PDFs) on the value of the QCD coupling strength ${\alpha }_s(M_Z)$. We explain a simple method that is rigorously valid in the quadratic approximation normally applied in PDF fitting, and fully reproduces the correlated dependence of theoretical cross sections on ${\alpha }_s$ and PDF parameters. This method is based on a statistical relation that allows one to add the uncertainty produced by ${\alpha }_s$, computed with some special PDF sets, in quadrature with the PDF uncertainty obtained for the fixed ${\alpha }_s$ value (such as the CTEQ6.6 PDF set). A series of four CTEQ6.6AS PDFs realizing this approach, for ${\alpha }_s$ values in the interval $0.116\le {\alpha }_s(M_Z)\le 0.120$, is presented. Using these PDFs, the combined ${\alpha }_s$ and PDF uncertainty is assessed for theoretical predictions at the Fermilab Tevatron and Large Hadron Collider. DOI: http://dx.doi.org/10.1103/PhysRevD.82.054021 © 2010 The American Physical Society

Extreme mass-ratio inspirals are crucial sources for future space-based gravitational wave detections. Gravitational waveforms emitted by extreme mass-ratio inspirals are closely related to the orbital dynamics of small celestial objects, which vary with the underlying spacetime geometry. Despite the tremendous success of general relativity, there are unsolved issues such as singularities in both black holes and cosmology. Loop quantum gravity, a theory addressing these singularity problems, offers a framework for regular black holes. In this paper, we focus on periodic orbits of a small celestial object around a supermassive quantum-corrected black hole in loop quantum gravity and compute the corresponding gravitational waveforms. We view the small celestial object as a massive test particle and obtain its four-velocity and effective potential. We explore the effects of quantum corrections on marginally bound orbits, innermost stable circular orbits, and other periodic orbits. Using the numerical kludge scheme, we further explore the gravitational waveforms of the small celestial object along different periodic orbits. The waveforms exhibit distinct zoom and whirl phases in a complete orbital period, closely tied to the quantum parameter α̂. We also perform a spectral analysis of the gravitational waves from these periodic orbits and assess their detectability. With the steady progress of space-based gravitational wave detection programs, our findings will contribute to utilizing extreme mass-ratio inspirals to test and understand the properties of quantum-corrected black holes.

A three-parameter (positive odd integer $s$, thickness factor $\lambda$, and asymmetry factor $a$) family of asymmetric thick brane solutions in five dimensions were constructed from a two-parameter ($s$ and $\lambda$) family of symmetric ones in by R. Guerrero, R. O. Rodriguez, and R. Torrealba in [ Phys. Rev. D 72, 124012 (2005).]. The values $s=1$ and $s\ge 3$ correspond to single branes and double branes, respectively. These branes have very rich inner structure. In this paper, by presenting the mass-independent potentials of Kaluza-Klein (KK) modes in the corresponding Schrödinger equations, we investigate the localization and mass spectra of fermions on the symmetric and asymmetric thick branes in an anti-de Sitter background. In order to analyze the effect of gravity-fermion interaction (i.e., the effect of the inner structure of the branes) and scalar-fermion interaction to the spectrum of fermion KK modes, we consider three kinds of typical kink-fermion couplings. The spectra of left chiral fermions for these couplings consist of a bound zero mode and a series of gapless continuous massive KK modes, some discrete bound KK modes including zero mode (exist mass gaps), and a series of continuous massive KK modes, infinite discrete bound KK modes, respectively. The structures of the spectra are investigated in detail.

We explore the discovery potential of ${W}^{$'${}}$ and ${Z}^{$'${}}$ boson searches for various $SU(2{)}_{1}$\bigotimes${}SU(2{)}_{2}$\bigotimes${}U(1{)}_{X}$ models at the Large Hadron Collider (LHC), after taking into account the constraints from low energy precision measurements and direct searches at both the Tevatron (1.96 TeV) and the LHC (7 TeV). In such models, the ${W}^{$'${}}$ and ${Z}^{$'${}}$ bosons emerge after the electroweak symmetry is spontaneously broken. Two patterns of the symmetry breaking are considered in this work: one is $SU(2{)}_{L}$\bigotimes${}SU(2{)}_{2}$\bigotimes${}U(1{)}_{X}$\rightarrow${}SU(2{)}_{L}$\bigotimes${}U(1{)}_{Y}$ (breaking pattern I), another is $SU(2{)}_{1}$\bigotimes${}SU(2{)}_{2}$\bigotimes${}U(1{)}_{Y}$\rightarrow${}SU(2{)}_{L}$\bigotimes${}U(1{)}_{Y}$ (breaking pattern II). Examining the single production channel of ${W}^{$'${}}$ and ${Z}^{$'${}}$ with their subsequent leptonic decays, we find that the probability of detecting ${W}^{$'${}}$ and ${Z}^{$'${}}$ bosons in the considered models at the LHC (with 14 TeV) is highly limited by the low energy precision data constraints. We show that observing ${Z}^{$'${}}$ alone, without seeing a ${W}^{$'${}}$, does not rule out new physics models with non-Abelian gauge extension, such as the phobic models in breaking pattern I. Models in breaking pattern II would predict the discovery of degenerate ${W}^{$'${}}$ and ${Z}^{$'${}}$ bosons at the LHC.