Multimeson production in pp interactions as a background for eta and eta' decays

Multimeson production in pp interactions comprises important background for eta, omega and eta' mesons production experiments and for the studies of their decays planned with WASA detector at COSY. The available information about the reactions is summarized and the need for efforts to describe the processes is stressed.Comment: Proceedings of MENU07 Conference Julich, Germany 200

TreeLex Meets Adjectival Tables

International audienceThe paper presents Treelex, a valence lexicon of French adjectives automatically extracted from a treebank. The corpus contains morphological and syntactic annotations but no subcategorisa- tion information is present for adjectives. Due to rich corpus annotations, our extraction method is guided by linguistic knowledge. The obtained lexicon (about 2000 adjectives and 40 frames) has been evaluated against hand-crafted adjec- tival tables described in (Picabia, 1978) and achieved 0.46 F-measure

Adjectives in TreeLex

International audienceThe paper presents an ongoing project on automatic extraction of subcategorization frames of French adjectives. The extraction method is guided by syntactic corpus annotations and heuristic rules. In particular, we use general linguistic knowledge to eliminate impersonal, comparative and certain adverbial constructions from the list of subcategorisation patterns

Large and noisy vs small and reliable: combining 2 types of corpora for adjective valence extraction

International audienceThis work investigates a possibility of combining two different types of corpora to build a valence lexicon for French adjectives. We complete adjectival frames extracted from a Treebank with statistical cues computed from a large automatically parsed corpus. This experiment shows how linguistic knowledge and large amount of annotated data can be used in a complementary manner

Two Approaches to Aspect Assignment in an English-Polish Machine Translation System

Abstract The paper presents two approaches to aspect assignment in a knowledgebased English-Polish machine translation (MT) system. The first method uses a set of heuristic rules based on interlingua (IR) representation provided by the system, whereas the other employs machine learning techniques. Both methods have similar performance and obtain high accuracy of over 88% on test data. The crucial difference, however, is the development effort: the machine learning technique is fully automatic, whereas heuristic rules are derived manually

Yangian description for decays and possible explanation of XX in the decay KL0→π0π0XK^0_L\to \pi^0 \pi^0 X

In this letter, hadronic decay channels of light pseudoscalar mesons are realized in Yangian algebra. In the framework of Yangian, we find that these decay channels can be formulated by acting transition operators, composed of the generators of Yangian, on the corresponding pseudoscalar mesons. This new description of decays allows us to present a possible interpretation of the new unknown particle $X$ in the decay $K^0_L\to \pi^0 \pi^0 X$: it is an entangled state of $\pi^0$ and $\eta$

Determination of the total width of the eta' meson

Taking advantage of both the low-emittance proton-beam of the Cooler Synchrotron COSY and the high momentum precision of the COSY-11 detector system, the mass distribution of the eta' meson was measured with a resolution of 0.33 MeV/c^2 (FWHM), improving the experimental mass resolution by almost an order of magnitude with respect to previous results. Based on the sample of more than 2300 reconstructed pp --> pp eta' events the total width of the eta' meson was determined to be 0.226 +- 0.017(stat.) +- 0.014(syst.) MeV/c^2.Comment: 4 pages, 4 figure

Anisotropy in the pion angular distribution of the reaction pp -> pp pi0 at 400 MeV

The reaction pp -> pp pi0 was studied with the WASA detector at the CELSIUS storage ring. The center of mass angular distribution of the pi0 was obtained by detection of the gamma decay products together with the two outgoing protons, and found to be anisotropic with a negative second derivative slope, in agreement with the theoretical predictions from a microscopic calculation.Comment: Revtex 4 style, 5 pages 7 figures, PACS numbers:13.60.Le, 13.75.Cs, 21.45.+v, 25.10.+

Observation of strong final-state effects in pi+ production in pp collisions at 400 MeV

Differential cross sections of the reactions $pp \to d\pi^+$ and $pp \to pn\pi^+$ have been measured at $T_p = 400$ MeV by detecting the charged ejectiles in the angular range $4^0 \leq \Theta_{Lab} \leq 21^\circ$. The deduced total cross sections agree well with those published previously for neighbouring energies. The invariant mass spectra are observed to be strongly affected by $\Delta$ production and $NN$ final-state interaction. The data are well described by Monte Carlo simulations including both these effects. The ratio of $pp \to pn\pi^+$ and $pp \to d\pi^+$ cross sections also compares favourably to a recent theoretical prediction which suggests a dominance of $np$-production in the relative $^3S_1$-state.Comment: 17 pages, 5 figure