Anomalous GPDs in the photon

We consider deeply virtual Compton scattering (DVCS) on a photon target, in the generalized Bjorken limit, at the Born order and in the leading logarithmic approximation. This leads us to the extraction of the photon anomalous generalized parton distributions (GPDs) \cite{url, DVCSphoton}.Comment: To appear in the proceedings of Photon 2007: International Conference on the Structure and Interactions of the Photon and the 17th International Workshop on Photon-Photon Collisions and International Workshop on High Energy Photon Linear Colliders, Paris, France, 9-13 Jul 200

Probing photon structure in DVCS on a photon target

The factorization of the amplitude for the deeply virtual Compton scattering (DVCS) process gamma*(Q) gamma -> gamma gamma at high Q2 is demonstrated in two distinct kinematical domains, allowing to define the photon generalized parton distributions and the diphoton generalized distribution amplitudes. Both these quantities exhibit an anomalous scaling behaviour and obey new inhomogeneous QCD evolution equations.Comment: 3 pages, 1 figure, to be published in the proceedings of the PANIC 2008 conference, Eilat (Israel), November 200

On threshold resummation beyond leading 1-x order

We check against exact finite order three-loop results for the non-singlet F_2 and F_3 structure functions the validity of a class of momentum space ansaetze for threshold resummation at the next-to-leading order in 1-x, which generalize results previously obtained in the large-\beta_0 limit. We find that the ansaetze do not work exactly, pointing towards an obstruction to threshold resummation at this order, but still yield correct results at the leading logarithmic level for each color structures, as well as at the next-to-next-to-leading logarithmic level for the specific C_F^3 color factor. A universality of the leading logarithm contributions to the physical evolution kernels of F_2 and F_3 at the next-to-leading order in 1-x is observed.Comment: v1:18 pages; v2: 26 pages, expanded version with new results for the F_3 structure function and added references; v3: more concise sections 3 and 4, improved discussion in section 5, added references, to be published in JHE

Deeply Virtual Compton Scattering on a Photon and Generalized Parton Distributions in the Photon

We consider deeply virtual Compton scattering on a photon target, in the generalized Bjorken limit, at the Born order and in the leading logarithmic approximation. We interpret the result as a factorized amplitude of a hard process described by handbag diagrams and anomalous generalized parton distributions in the photon. This anomalous part, with its characteristic ln Q2 dependence, is present both in the DGLAP and in the ERBL regions. As a consequence, these generalized parton distributions of the photon obey DGLAP-ERBL evolution equations with an inhomogeneous term

Tourteau d'arachide détoxifié dans l'alimentation des volailles

L'utilisation comparée dans l'alimentation de poulettes et de poussins de tourteau contenant de l'aflatoxine et de tourteau purifié par un procédé alcalin a montré que ce dernier donnait une production d'oeufs plus importante, un taux d'éclosion meilleur, les poids et taux de consommation chez les adultes étant par ailleurs identiques pour les deux provende

Constant terms in threshold resummation and the quark form factor

We verify to order alpha_s^4 two previously conjectured relations, valid in four dimensions, between constant terms in threshold resummation (for Deep Inelastic Scattering and the Drell-Yan process) and the second logarithmic derivative of the massless quark form factor. The same relations are checked to all orders in the large beta_0 limit; as a byproduct a dispersive representation of the form factor is obtained. These relations allow to compute in a symmetrical way the three-loop resummation coefficients B_3 and D_3 in terms of the three-loop contributions to the virtual diagonal splitting function and to the quark form factor, confirming results obtained in the literature.Comment: 39 pages, no figure; version 2: same content, but improved presentation, with a new section devoted to the variety of resummation procedures; version 3: journal version, where a remark about the all orders validity of the conjecture in the DIS case is reporte

Photon Generalized Parton Distributions

We present a calculation of the generalized parton distributions of the photon using overlaps of photon light-front wave functions.Comment: Talk given at LightCone 2011, 4 pages, 3 figure

La paille de riz dans l'alimentation animale au Sénégal. II. Biochimie du rumen - Embouche intensive - Conclusions

Dans une première partie, les auteurs étudient les résultats des analyses bromatologiques des digestibilités in vivo et de bilans minéraux effectués à partir de la paille de riz. La 2e partie intéresse la production des nutriments obtenus au niveau du rumen avec des rations à base de paille de riz, les résultats d'expérimentation d'embouche intensive avec des rations comportant ce fourrage. La paille de riz correctement supplémentée en azote et en sels minéraux peut constituer de 30 à 70 p. 100 de l'apport énergétique de rations d'embouche capables de produire de 400 à 800 g de croît journalier. A ce titre, les 150 000 tonnes de paille de riz disponibles au Sénégal pourraient contribuer dans une large mesure à la préparation bouchère de plus de 100 000 têtes de bétai

La paille de riz dans l'alimentation animale au Sénégal. I. Analyses bromatologiques, digestibilité in vivo et in vitro, bilans azotés et minéraux

La paille de riz est un fourrage abondant au Sénégal: 150 000 t sont disponibles à l'heure actuelle et ces quantités doivent doubler dans les dix années à venir. Ce fourrage qui, distribué seul, constitue un aliment très incomplet, est actuellement peu et mal utilisé. Afin de déterminer les modalités d'une alimentation rationnelle avec ce fourrage, les auteurs rapportent les résultats des nombreux travaux de laboratoire effectués sur ce sous-produit. La première partie intéresse sa composition chimique, les résultats des digestibilités in vivo et in vitro, les bilans azotés et minérau

The S-parameter in Holographic Technicolor Models

We study the S parameter, considering especially its sign, in models of electroweak symmetry breaking (EWSB) in extra dimensions, with fermions localized near the UV brane. Such models are conjectured to be dual to 4D strong dynamics triggering EWSB. The motivation for such a study is that a negative value of S can significantly ameliorate the constraints from electroweak precision data on these models, allowing lower mass scales (TeV or below) for the new particles and leading to easier discovery at the LHC. We first extend an earlier proof of S>0 for EWSB by boundary conditions in arbitrary metric to the case of general kinetic functions for the gauge fields or arbitrary kinetic mixing. We then consider EWSB in the bulk by a Higgs VEV showing that S is positive for arbitrary metric and Higgs profile, assuming that the effects from higher-dimensional operators in the 5D theory are sub-leading and can therefore be neglected. For the specific case of AdS_5 with a power law Higgs profile, we also show that S ~ + O(1), including effects of possible kinetic mixing from higher-dimensional operator (of NDA size) in the $5D$ theory. Therefore, our work strongly suggests that S is positive in calculable models in extra dimensions.Comment: 21 pages, 2 figures. v2: references adde