Intrinsic Charm Contribution to Double Quarkonium Hadroproduction

Double $J/\psi$ production has been observed by the NA3 collaboration in $\pi N$ and $p N$ collisions with a cross section of the order of 20-30 pb. The $\psi \psi$ pairs measured in $\pi^-$ nucleus interactions at 150 and 280 GeV$/c$ are observed to carry an anomalously large fraction of the projectile momentum in the laboratory frame, $x_{\psi \psi} \geq 0.6$ at 150 GeV$/c$ and $\geq 0.4$ at 280 GeV$/c$. We postulate that these forward $\psi \psi$ pairs are created by the materialization of Fock states in the projectile containing two pairs of intrinsic $c \overline c$ quarks. We calculate the overlap of the charmonium states with the $|\overline u d c \overline c c \overline c \rangle$ Fock state as described by the intrinsic charm model and find that the $\pi^- N \rightarrow \psi \psi$ longitudinal momentum and invariant mass distributions are both well reproduced. We also discuss double $J/\psi$ production in $pN$ interactions and the implications for other heavy quarkonium production channels in QCD.Comment: Revtex, APS style, 7 pages, 3 figures in uuencoded fil

QCD Mechanisms for Double Quarkonium and Open Heavy Meson Hadroproduction

Double $J/\psi$ production on the order of 20-30 pb has been observed by the NA3 collaboration. These $\psi \psi$ pairs, measured in $\pi^- N$ interactions at 150 and 280 GeV$/c$ and in $pN$ interactions at 400 GeV$/c$, carry a large fraction of the projectile momentum, $x_{\psi \psi} \geq 0.6$ for the 150 GeV$/c$ beam and $\geq 0.4$ at 280 GeV$/c$. We examine several sources of $\psi \psi$ pair production within QCD, including ${\cal O}(\alpha_s^4)$ $\psi \psi$ production, leading-twist $b \overline b$ production and decay, and the materialization of heavy-quark Fock states in the projectile. We estimate the production cross section and the single and double $J/\psi$ momentum and mass distributions for each, comparing the results with the NA3 data, and predict $\psi \psi$ production in $pN$ interactions at 800 GeV$/c$, accessible to current fixed-target experiments. We also discuss the observable implications of open heavy meson pair production from the intrinsic heavy quark Fock states.Comment: Revtex, APS style, 16 pages, 15 figures available as uuencoded postscript files (or ps files) from the Autho

Dissolution and Precipitation of Gypsum in the Soil Under Irrigation

Two soils were used in this soil column study. Yolo loam soil a non- c al c areous, non-gypsiferous soil from central California and Vernal soil a calcareous soil from eastern Utah. Initial studies were conducted where the solubilities of pure CaC0 3 and CaS0 4 \u27 2H 2 0 were determined in the presence of Logan river water, a KCl solution (2.8 mmhos/cm) and a K 2 S0 4 solution (Z. 7 mmhos/cm). Gypsum was more soluble in the KCl solution than in the K Z S0 4 solution. The solubility product of both gypsum and lime were determined from the analytical data. The formation of CaS0 4 0 and caco 3 0 ion pairs were cons idered to be the most important complex ions pres ent. A reasonable agreement was observed between the theoretical values of K and the ca lculated K sp sp Essentially the same results were obtained when these waters were used in leaching the columns of Yolo and Vernal soil columns The solubility of gypsUJn was greatest usmg the KCl leaching\u27 solution and least using the K 2504 leaching solution. Logan river water gave intermediate values. Calcium carbonate was most soluble in the K 2504 leaching solution and les s in the KCl solution. It was found that measuring the ci+ concentration in the effluent was a more reliable index to steady state condition than using an electrical conductivity lneasurement. Unsaturated flow removed more salt per unit volume of effluent than saturated flow. The relative area method was used to analyze the effluent under saturated moisture flow. 2+ It was found that a certain amount of Ca derived from gypsum dissolution precipitated in the column as CaC0 3 . This amount 2+ , was greater than 15% of the Ca dlssolved from gypsum

Higher Twist Contributions To R-Hadron Phenomenology In The Light Gluino Scenario

The open light gluino window allows non-trivial higher twist gluino contributions to the proton wave function. Using a two-component model originally developed for charm hadroproduction, higher twist intrinsic gluino contributions to final state R-hadron formation are shown to enhance leading twist production in the forward $x_{F}$ region. We calculate R-hadron production at $p_{\rm{lab}}=800$ GeV in pp, pBe, and pCu interactions with light gluino masses of 1.2, 1.5, 3.5, and 5.0 GeV.Comment: 22 pages, 10 figures, revte

Matthieu Séguéla, Clemenceau ou la tentation du Japon

Combien de vies Georges Clemenceau (1841-1929) a-t-il eues ? Pas moins de neuf affirme Jean Garrigues dans son dernier ouvrage consacré à ce drôle de félin qu’est le « Tigre ». Plus que jamais après la publication du livre de Matthieu Séguéla, qui aborde la relation passionnée de Georges Clemenceau avec le Japon, nous sommes tentés de croire la célèbre légende égyptienne. Même si le parcours de ce « monstre absolu » de la Troisième République, totalement hors norme, a été traqué en tous sens ..

Alexandre Ribot et la République modérée : formation et ascension d'un homme politique libéral (1858-1895)

Despite a very impressive curriculum vitae (a parliamentarian for more than forty-four years, eleven times a minister and five times the president of the Council), one cannot but recognize that Alexandre Ribot (1842-1923) has received little attention from historians and has almost disappeared from collective memory. This raises questions, especially given the fact that the sources related to him, including a very rich set of private records, are quite abundant. Though our inquiry only covers a certain phase of Alexandre Ribot’s long career (1858-1895), it however aims at going beyond the strict biographical framework to tackle the political structures of the early Third Republic so as to identify their dynamics, embedded within different timeframes.By focusing on Alexandre Ribot’s building up as a politician and on his rise to power, this research aims at analysing his career-path while integrating it within the context of the establishment of the French Republican model. It thus makes a contribution to different ongoing historiographical initiatives regarding the “world of the Third Republic” (G. and S. Berstein), such as the working of “absolute parliamentarianism” (Carré de Malberg), the professionalization of political staff or the influence of liberalism and of the Liberals in the setting up of the regime.En dépit d’un très impressionnant curriculum vitae (parlementaire pendant plus de quarante-quatre ans, onze fois ministre et cinq fois président du Conseil), force est de reconnaître qu’Alexandre Ribot (1842-1923) a peu retenu l’attention des historiens et quasiment disparu de la mémoire collective. Ce constat interroge d’autant plus que les sources le concernant sont particulièrement abondantes, avec notamment un très riche ensemble d’archives privées. Si notre investigation n’embrasse qu’une tranche de la longue carrière d’Alexandre Ribot (1858-1895), elle ambitionne en revanche de dépasser le strict cadre biographique pour aborder les structures politiques des débuts de la Troisième République et d’en dégager les dynamiques, inscrites dans différentes temporalités.En se structurant autour de la formation et de l’ascension politique d’Alexandre Ribot, notre recherche vise à analyser sa trajectoire en l’inscrivant dans le contexte de l’ancrage du modèle républicain français, apportant ainsi une contribution à différents chantiers historiographiques en cours concernant le « monde de la Troisième République » (G. et S. Berstein) tels que le fonctionnement du « parlementarisme absolu » (Carré de Malberg), la professionnalisation du personnel politique, ou encore l’influence du libéralisme et des libéraux dans l’installation du régime

Pion Structure Function in the Nambu and Jona-Lasinio model

The pion structure function is studied in the Nambu and Jona-Lasinio (NJL) model. We calculate the forward scattering amplitude of a virtual photon from a pion target in the Bjorken limit, and obtain valence quark distributions of the pion at the low energy hadronic scale, where the NJL model is supposed to work. The calculated distribution functions are evolved to the experimental momentum scale using the Altarelli-Parisi equation. The resulting distributions are in a reasonable agreement with experiment. We calculate also the kaon structure function and compare the ratio of kaon to pion valence u-quark distributions with experiment.Comment: 15 pages with 5 figures as uuencoded postscript files, TMU-NT-930301 (plain LaTeX

Sparse wavelet-based solutions for the M/EEG inverse problem

This paper is concerned with variational and Bayesian approaches to neuro-electromagnetic inverse problems (EEG and MEG). The strong indeterminacy of these problems is tackled by introducing sparsity inducing regularization/priors in a transformed domain, namely a spatial wavelet domain. Sparsity in the wavelet domain allows to reach ''data compression'' in the cortical sources domain. Spatial wavelets defined on the mesh graph of the triangulated cortical surface are used, in combination with sparse regression techniques, namely LASSO regression or sparse Bayesian learning, to provide localized and compressed estimates for brain activity from sensor data. Numerical results on simulated and real MEG data are provided, which outline the performances of the proposed approach in terms of localization

Meson Structure in Deep Inelastic Scattering

We study the deep inelastic structure functions of mesons within the Nambu and Jona-Lasinio model. We calculate the valence quark distributions in $\pi$, $K$, and $\rho$ mesons at the low energy model scale, which are evoluted to the experimental momentum scale in terms of the Altarelli-Parisi equation. The resulting distribution functions show reasonable agreements with experiment. We also discuss the semi-inclusive lepton nucleon scattering process with a slow nucleon in coincidence in the final state, which reveals the off-shell structure of the pion.Comment: 31 pages with 16 figures as uuencoded postscript files, TMU-NT-940101 (plain LaTeX

Meson Structure Functions in Valon Model

Parton distributions in a {\it{valon}} in the next-to-leading order is used to determine the patron distributions in pion and kaon. The validity of the valon model is tested and shown that the partonic content of the valon is universal and independent of the valon type. We have evaluated the valon distribution in pion and kaon, and in particular it is shown that the results are in good agreement with the experimental data on pion structure in a wide range of $x=[10^{-4},1]$Comment: 13 pages with 7 figures included, The manuscript is revised, figures are added and some errors are corrected. Accepted for publication in Physical Review