Comparison of Certain Results of Simultaneous Measurements of Solar Wind Characteristics on Spacecrafts ''Venera-3'' and ''Pioneer-6''

Ion concentration, ion velocity, and other solar wind characteristics measured simultaneously aboard spacecraf

Estrogen Receptor-α in the Bed Nucleus of the Stria Terminalis Regulates Social Affiliation in Male Prairie Voles (Microtus ochrogaster)

Estrogen receptor alpha (ERα) typically masculinizes male behavior, while low levels of ERα in the medial amygdala (MeA) and the bed nucleus of the stria terminalis (BST) are associated with high levels of male prosocial behavior. In the males of the highly social prairie vole (Microtus ochrogaster), increasing ERα in the MeA inhibited the expression of spontaneous alloparental behavior and produced a preference for novel females. To test for the effects of increased ERα in the BST, a viral vector was used to enhance ERα expression in the BST of adult male prairie voles. Following treatment, adult males were tested for alloparental behavior with 1–3-day-old pups, and for heterosexual social preference and affiliation. Treatment did not affect alloparental behavior as 73% of ERα-BST males and 62.5% of control males were alloparental. Increasing ERα in the BST affected heterosexual affiliation, with ERα-BST males spending significantly less total time in side-by-side contact with females relative to time spent with control males. ERα-BST males did not show a preference for either the familiar or novel female. These findings differed significantly from those reported in ERα-MeA enhanced males, where ERα inhibited alloparental behavior and produced a preference for a novel female. The findings from this study suggest two things: first, that increased ERα in the BST decreases social affiliation and second, that altering ERα in different regions of the social neural circuit differentially impacts the expression of social behavior

On the NLO Power Correction to Photon-Pion Transition Form Factor

We propose a perturbative evaluation for the next-to-leading-order (NLO) $O(1/Q^4)$ power correction to the photon-pion transition form factor. The effects of the NLO power correction are analyzed.Comment: 4 pages, 3 figures, Revtex, revised versio

Approach to Perturbative Results in the N-Delta Transition

We show that constraints from perturbative QCD calculations play a role in the nucleon to Delta(1232) electromagnetic transition even at moderate momentum transfer scales. The pQCD constraints, tied to real photoproduction data and unseparated resonance response functions, lead to explicit forms for the helicity amplitudes wherein the E2/M1 ratio remains small at moderately large momentum transfer.Comment: 4 pages, 2 figures, ReVTe

Unbiased analysis of CLEO data at NLO and pion distribution amplitude

We discuss different QCD approaches to calculate the form factor F^{\gamma^*\gamma\pi}(Q^2) of the \gamma^*\gamma\to\pi^{0} transition giving preference to the light-cone QCD sum rules (LCSR) approach as being the most adequate. In this context we revise the previous analysis of the CLEO experimental data on F^{\gamma^*\gamma\pi}(Q^{2}) by Schmedding and Yakovlev. Special attention is paid to the sensitivity of the results to the (strong radiative) \alpha_s-corrections and to the value of the twist-four coupling \delta^2. We present a full analysis of the CLEO data at the NLO level of LCSRs, focusing particular attention to the extraction of the relevant parameters to determine the pion distribution amplitude, i.e., the Gegenbauer coefficients a_2 and a_4. Our analysis confirms our previous results and also the main findings of Schmedding and Yakovlev: both the asymptotic, as well as the Chernyak--Zhitnitsky pion distribution amplitudes are completely excluded by the CLEO data. A novelty of our approach is to use the CLEO data as a means of determining the value of the QCD vacuum non-locality parameter \lambda^2_q = / =0.4 GeV^2, which specifies the average virtuality of the vacuum quarks.Comment: 25 pages, 5 figures, 4 tables; format and margins corrected to fit page size; small changes in the text and correction of misprint

Hard exclusive processes and higher-order QCD corrections

The short review of the higher order corrections to the hard exclusive processes is given. Different approaches are discussed and the importance of higher-order calculations is stressed.Comment: 17 pages; talk given at the 9th Adriatic Meeting, Dubrovnik 200

Perturbative QCD factorization of πγ∗→γ(π)\pi \gamma^*\to \gamma(\pi) and B→γ(π)lνˉB\to \gamma(\pi)l\bar \nu

We prove factorization theorem for the processes $\pi\gamma^*\to\gamma$ and $\pi\gamma^*\to\pi$ to leading twist in the covariant gauge by means of the Ward identity. Soft divergences cancel and collinear divergences are grouped into a pion wave function defined by a nonlocal matrix element. The gauge invariance and universality of the pion wave function are confirmed. The proof is then extended to the exclusive $B$ meson decays $B\to\gamma l\bar\nu$ and $B\to\pi l\bar\nu$ in the heavy quark limit. It is shown that a light-cone $B$ meson wave function, though absorbing soft dynamics, can be defined in an appropriate frame. Factorization of the $B\to\pi l\bar\nu$ decay in $k_T$ space, $k_T$ being parton transverse momenta, is briefly discussed. We comment on the extraction of the leading-twist pion wave function from experimental data.Comment: 21 pages in Latex file, version to appear in Phys. Rev.

An attempt to understand exclusive pi+ electroproduction

Hard exclusive pi+ electroproduction is investigated within the handbag approach. The prominent role of the pion-pole contribution is demonstrated. It is also shown that the experimental data require a twist-3 effect which ensues from the helicity-flip generalized parton distribution H_T and the twist-3 pion wave function. The results calculated from this handbag approach are compared in detail with the experimental data on cross sections and spin asymmetries measured with a polarized target. It is also commented on consequences of this approach for exclusive \pi^0 and vector-meson electroproduction.Comment: 35 pages, 12 figures, using Latex, a number of additional comments have been included in the text, e.g. in paragraph above (3) or at end of sect.

Deeply virtual electroproduction of photons and mesons on the nucleon : leading order amplitudes and power corrections

We estimate the leading order amplitudes for exclusive photon and meson electroproduction reactions at large Q^2 in the valence region in terms of skewed quark distributions. As experimental investigations can currently only be envisaged at moderate values of Q^2, we estimate power corrections due to the intrinsic transverse momentum of the partons in the meson wavefunction and in the nucleon. To this aim the skewed parton distribution formalism is generalized so as to include the parton intrinsic transverse momentum dependence. Furthermore, for the meson electroproduction reactions, we calculate the soft overlap type contributions and compare with the leading order amplitudes. We give first estimates for these different power corrections in kinematics which are relevant for experiments in the near future.Comment: 59 pages, 21 figure