J. M. Laget

Pion and kaon photoproduction at high-energies: Forward and intermediate angles

Abstract A model for high energy pion and kaon photoproduction (Eγ ≳ 4 GeV) is presented which interpolates between the low and higher momentum transfer regions. At low momentum transfer (which is described in terms of Regge trajectory exchanges), the model is able to give an economical description of unpolarized and polarized data for both the charged and neutral pion photoproduction reactions as well as for K+Λ and K+Σ photoproduction data, available at high energy. At higher momentum transfer, an extrapolation based on saturating Regge trajectories, and which satisfies scaling laws at asymptotically large transfers, is found able to describe the few existing γp → nπ+ data. The model can be used as a guidance to interpret forthcoming data at larger momentum transfers.

The Space-time structure of hard scattering processes

Recent studies of exclusive electroproduction of vector mesons at JLab make it possible for the first time to play with two independent hard scales: the virtuality

Pseudoscalar meson photoproduction at high energies: from the Regge regime to the hard scattering regime

{Q}^{2}

The electro-disintegration of few body systems revisited

of the photon, which sets the observation scale, and the momentum transfer

Exclusive electromagnetic production of strangeness on the nucleon: Regge analysis of recent data

t

Probing the high momentum component of the deuteron at high Q2.

to the hadronic system, which sets the interaction scale. They reinforce the description of hard-scattering processes in terms of few effective degrees of freedom relevant to the JLab-Hermes energy range.

Unitarity constraints on deeply virtual Compton scattering

Abstract A model for high energy pion photoproduction is presented which interpolates between the low and high momentum transfer regions. At low momentum transfer (which is described in terms of Regge trajectory exchanges), the model is able to give an economical description of the numerous high energy unpolarized and polarized γN → πN data. At higher momentum transfer, a description based on saturating Regge trajectories and which satisfies quark counting rules at asymptotically large transfers, is found able to describe the few existing γp → nπ+ data. The model can be used as a guidance to interpret forthcoming data at large momentum transfers.

The 3He(e, e′p) reactions and the components of the 3He wave function

Abstract Recent studies of the electro-disintegration of the few body systems at JLab have revived the field. Not only recoil momentum distributions have been determined in a single shot. But also they confirm that the diagrammatic approach, which I developed 25 years ago, is relevant to analyze them, provided that the nucleon–nucleon scattering amplitude, determined in the same energy range, is used. They provide us with a solid starting point to address the issue of the propagation of exotic components of hadrons in nuclear matter.

Rescattering in meson photoproduction from few body systems

In view of the numerous experimental results recently released, we provide in this paper an update on the performance of our simple Regge model for strangeness electroproduction on the nucleon. Without refitting any parameters, a decent description of all measured observables and channels is achieved. We also give predictions for spin transfer observables, recently measured at Jefferson Lab, which have high sensitivity to discriminate between different theoretical approaches.

Unitarity constraints on neutral pion electroproduction

W.U. Boeglin, L. Coman, P. Ambrozewicz, K. Aniol, J. Arrington, G. Batigne, P. Bosted, A. Camsonne, G. Chang, J.P. Chen, S. Choi, A. Deur, M. Epstein, J.M. Finn, ∗ S. Frullani, C. Furget, F. Garibaldi, O. Gayou, 5 R. Gilman, 5 O. Hansen, D. Hayes, D.W. Higinbotham, W. Hinton, C. Hyde, H. Ibrahim, 11 C.W. de Jager, X. Jiang, M. K. Jones, L.J. Kaufman, † A. Klein, S. Kox, L. Kramer, G. Kumbartzki, J.M. Laget, J. LeRose, R. Lindgren, D.J. Margaziotis, P. Markowitz, K. McCormick, Z. Meziani, R. Michaels, B. Milbrath, J. Mitchell, ‡ P. Monaghan, M. Moteabbed, P. Moussiegt, R. Nasseripour, K. Paschke, C. Perdrisat, E. Piasetzky, V. Punjabi, I.A. Qattan, 3 G. Quéméner, R.D. Ransome, B. Raue, J.S. Réal, J. Reinhold, B. Reitz, R. Roché, M. Roedelbronn, A. Saha, ∗ K. Slifer, P. Solvignon, V. Sulkosky, § P.E. Ulmer, ‡ E. Voutier, L.B. Weinstein, B. Wojtsekhowski, and M. Zeier