The Hilbert-Space Structure of Non-Hermitian Theories with Real Spectra

We investigate the quantum-mechanical interpretation of models with non-Hermitian Hamiltonians and real spectra. After describing a general framework to reformulate such models in terms of Hermitian Hamiltonians defined on the Hilbert space $L_2(-\infty,\infty)$, we discuss the significance of the algebra of physical observables.Comment: 5 pages, uses iopart.cls. Talk given by R. Kretschmer at the 1st International Workshop on Pseudo-Hermitian Hamiltonians in Quantum Physics, Prague, Czech Republic, June 16-17, 2003. To appear in the proceeding

The nucleon's transversity and the photon's distribution amplitude probed in lepton pair photoproduction

We describe a new way to access the chiral odd transversity parton distribution in the proton through the photoproduction of lepton pairs on transversely polarized target. The basic ingredient is the interference of the Bethe Heitler or Drell-Yan amplitudes with the amplitude of a process, where the photon couples to quarks through its twist-2 chiral-odd distribution amplitude. This approach permits to scan experimentally the shape of the transversity distribution in a nucleon as well as the photon distribution amplitude.Comment: 4 pages, proceedings of the ICHEP conference, Paris july 201

Neutrino-production of a charmed meson and the transverse spin structure of the nucleon

We calculate the amplitude for exclusive neutrino production of a charmed meson on an unpolarized target, in the colinear QCD approach where generalized parton distributions (GPDs) factorize from perturbatively calculable coefficient functions. We demonstrate that the transversity chiral odd GPDs contribute to the transverse cross section if the hard amplitude is calculated up to order mc/Q. We show how to access these GPDs through the azimuthal dependence of the nu N -> mu D N differential cross section.Comment: 5 pages, 1 figure. Version 2 adds a few clarifications and references. As published in Physical Review Letters 115, 092001 (2015

Next-to-leading gluonic reggeons in the high-energy effective action

We study the next-to-leading gluon exchange in the high-energy scattering that contributes to the amplitude to order $s^0$ up to logarithmic corrections. Similar to the leading gluon exchange these contribution can be described in terms of reggeon exchanges. There are several gluonic reggeons at the next-to-leading level. Some of them transfer parity or gauge group representation different from the leading gluonic reggeon. Unlike the leading one they are sensitive to the helicity and transverse momenta of the scattering partons. We extend the high-energy effective action and derive from the action of gluodynamics the terms describing the next-to-leading reggeons and their interaction in the multi-Regge approximation.Comment: 31 pages in LATEX, 4 eps figures, references adde