Virtual Photon Structure Functions

We discuss the perturbatively calculable virtual photon structure functions. First we present the framework for analyzing the structure functions of the virtual photon and derive a first moment of $g_1^\gamma$ of the virtual photon. We then investigate the three positivity constraints satisfied by the eight structure functions of the virtual photon.Comment: 5 pages, LaTeX, 5 eps figures, npb.sty file included Talk given at RADCOR/Loops and Legs 2002, Kloster Banz, Germany, September 8-13, 2002, to appear in the Proceeding

Nucleon spin structure and its connections to various sum rules

Our knowledge on the nucleon spin structure has greatly improved over the last twenty years or so, but still many fundamental questions remain unsolved. I will try to review some of the puzzling aspects of the origin of the nucleon spin. I will emphasize the connection with several sum rules and, when using this tool, the relevance of some kinematic regions for testing them in the QCD dynamics framework.Comment: 10 pages, 4 figures, Invited talk presented at GDH2004, June 2-5 2004, Old Dominion University, Virginia, US

Do we understand elastic scattering up to LHC energies?

The measurements of high energy \bar p p and pp elastic at ISR, SPS and Tevatron colliders have provided usefull informations on the behavior of the scattering amplitude. A large step in energy domain is accomplished with the LHC collider presently running, giving a unique opportunity to improve our knowledge on the asymptotic regime of the elastic scattering amplitude and to verify the validity of our theoretical approach, to describe the total cross section \sigma_{tot}(s), the total elastic cross section \sigma_{el}(s), the ratio of the real to imaginary parts of the forward amplitude \rho(s) and the differential cross section d\sigma (s,t)/dt.Comment: 6 pages, 2 figures, Invited talk at " DIFFRACTION 2012"', Puerto del Carmen, Lanzarote Canary Islands (Spain), September 10-15 2012, to appear in AIP Conference Proceedings (2013

What Is A Number? Re-Thinking Derrida's Concept of Infinity

Iterability, the repetition which alters the idealization it reproduces, is the engine of deconstructive movement. The fact that all experience is transformative-dissimulative in its essence does not, however, mean that the momentum of change is the same for all situations. Derrida adapts Husserl's distinction between a bound and a free ideality to draw up a contrast between mechanical mathematical calculation, whose in-principle infinite enumerability is supposedly meaningless, empty of content, and therefore not in itself subject to alteration through contextual change, and idealities such as spoken or written language which are directly animated by a meaning-to-say and are thus immediately affected by context. Derrida associates the dangers of cultural stagnation, paralysis and irresponsibility with the emptiness of programmatic, mechanical, formulaic thinking. This paper endeavors to show that enumerative calculation is not context-independent in itself but is instead immediately infused with alteration, thereby making incoherent Derrida's claim to distinguish between a free and bound ideality. Along with the presumed formal basis of numeric infinitization, Derrida's non-dialectical distinction between forms of mechanical or programmatic thinking (the Same) and truly inventive experience (the absolute Other) loses its justification. In the place of a distinction between bound and free idealities is proposed a distinction between two poles of novelty; the first form of novel experience would be characterized by affectivites of unintelligibility , confusion and vacuity, and the second by affectivities of anticipatory continuity and intimacy

Looking into the Future of Spin and QCD

Several stimulating open questions in high energy spin physics will be described together with the striking progress recently achieved in this field. In view of the new experimental facilities and the new tools, soon available, I will try to anticipate what we will learn next. The prospects for the future are excellent and clearly, some exciting times are ahead of us.Comment: Closing Lecture at SPIN2002, BNL 8-14/09/02, 10 pages, 3 figure

A new search strategy for the Higgs boson

We propose a novel mechanism for exclusive diffractive Higgs production $pp \to Hpp$, in which the Higgs carries a significant fraction of the projectile proton's momentum. This mechanism will then provide a clear experimental signal for Higgs production, due to the small background in this kinematic region. The key assumption underlying our analysis is the presence of intrinsic charm (IC) and intrinsic bottom (IB) fluctuations in the proton bound state, whose existence, at high light-cone momentum fraction $x$, has a substantial and growing experimental and theoretical support.Comment: 4 pages, 1 figure, Talk presented at the International Conference on QCD and Hadronic Physics, Beijing, June 16-20 (2005