Short lists with short programs in short time - a short proof

Bauwens, Mahklin, Vereshchagin and Zimand [ECCC TR13-007] and Teutsch [arxiv:1212.6104] have shown that given a string x it is possible to construct in polynomial time a list containing a short description of it. We simplify their technique and present a shorter proof of this result

Evolution and models for skewed parton distributions

We discuss the structure of the ``forward visible'' (FW) parts of double and skewed distributions related to usual distributions through reduction relations. We use factorized models for double distributions (DDs) f(x, alpha) in which one factor coincides with the usual (forward) parton distribution and another specifies the profile characterizing the spread of the longitudinal momentum transfer. The model DDs are used to construct skewed parton distributions (SPDs). For small skewedness, the FW parts of SPDs H(x, xi) can be obtained by averaging forward parton densities f(x- xi alpha) with the weight rho (alpha) coinciding with the profile function of the double distribution f(x, alpha) at small x. We show that if the x^n moments f_n (alpha) of DDs have the asymptotic (1-alpha^2)^{n+1} profile, then the alpha-profile of f (x,alpha) for small x is completely determined by small-x behavior of the usual parton distribution. We demonstrate that, for small xi, the model with asymptotic profiles for f_n (alpha) is equivalent to that proposed recently by Shuvaev et al., in which the Gegenbauer moments of SPDs do not depend on xi. We perform a numerical investigation of the evolution patterns of SPDs and gave interpretation of the results of these studies within the formalism of double distributions.Comment: 24 pages, Latex, 12 figure

Private equity industry: Southwest firms draw on regional expertise

Neiman Marcus, Harrah’s, Petco, J. Crew—these well-known names are among the holdings of companies owned or co-owned by private equity (PE) firms in the Federal Reserve’s Eleventh District. The region is home to more than 175 PE firms, including the world’s third-largest, Fort Worth-based TPG Capital.[1] Together, these entities have raised more than $109 billion over the past 10 years and sit on$31 billion pending investment. ; While the PE business model goes back to the times of early seafaring enterprises funded by limited private partners, its modern U.S. iteration dates back to the 1950s and the first venture capital funds. More recently, the industry and its sometimes opaque operations have come under increased regulatory scrutiny amid concern about their riskiness and systemic importance to the financial system. Although detailed data are hard to come by, regionally based PE firms are distinguished from their counterparts nationwide by the sectors they favor.Investments ; Venture capital

Virtual Compton Scattering Processes in Quantum Chromodynamics

Applications of perturbative QCD to deeply virtual Compton scattering and hard exclusive meson electroproduction processes require a generalization of usual Parton distributions for the case when long-distance information is accumulated in nonforward matrix elements [special characters omitted] of quark and gluon light-cone operators. We consider different aspects of the investigation of the virtual Compton amplitude in the QCD on two examples: the spin dependent observables in the forward virtual Compton process (measured in the experiments on deep inelastic scattering) and the γγ* transition form factor. Then we discuss in detail evolution equations for non-forward parton distributions [special characters omitted] The latter are constructed from simple models for double distributions [special characters omitted] with correct spectral and symmetry properties. They also satisfy the reduction relations connecting them to the usual (forward) parton densities [special characters omitted] We obtain solutions for evolution equations for non-forward quark and gluon parton obtain solutions for evolution equations for non-forward quark and gluon parton distributions and show that the models are consistent with the evolution. Using these models, we give an estimate for the cross section of deeply virtual Compton scattering for the kinematics of CEBAF at Jefferson Lab

Power-Law Wave Functions and Generalized Parton Distributions for Pion

We propose a model for generalized parton distributions of the pion based on the power-law ansatz for the effective light-cone wave function.Comment: 27 pages, Latex; Revised and Extended Version, to be published in Phys. Rev.