F. Drago

Parity doublet conspiracy of the pion from finite energy sum rules in π+ photoproduction

Abstract We test the essential features of the conspiracy of the pion Regge pole with a positive parity pole in π + photoproduction, using finite energy sum rules. In particular we find that the pion residue function varies rapidly with the four momentum transfer t vanishing at t = −0.03 GeV 2 and the conspirator trajectory chooses nonsense at α = 0.

Determination of the pion and conspirator residues and trajectories in π+ photoproduction from continuous moment sum rules

Abstract Using continuous moment sum rules we obtain a clear evidence for the pion conspiracy. We find the pion and conspirator residues and trajectories, which reproduce with accuracy the forward peak in the high-energy differential cross section.

“Mass formula” for M=0 and M=1 toller families

Abstract A method to derive the so-called mass formulae, based on analyticity alone, is presented. The simpler M =0 case is discussed in some detail. The behaviour of the residue functions is also studied; using the factorization theorem the Toller pole is reconstructed. The mass formula for M =1 is given.

Unitarity and Veneziano-like pion form factor

SummaryWe study a unitarization method in connection with the recently proposed Veneziano-like models for the pion electromagnetic form factor. Using as input the model proposed by Suura, good agreement is obtained with the experimental data in the timelike region.RiassuntoSi studia un metodo di unitarizzazione in connessione coi modelli alla Veneziano recentemente proposti per il fattore di forma elettromagnetico del pione. Usando come punto di partenza il modello proposto da Suura si trova un buon accordo con i dati sperimentali nella regione temporale.РезюмеМы исследуем метод унитаризации в связи с недавно предложенными моделями, подобными модели Венециано, для электромагнитного формфактора. Используя, как исходное, модель, предложенную Суура, получается хорошее согласие с экспериментальными данными во времени-подобной области.

Finite energy sum rules and the crossover problem in K - N scattering

Abstract We study the behaviour of the ω-residue functions in kaon-nucleon elastic scattering using the “finite energy sum rules” technique. We find that both spin flip and non spin flip ω-residues show a zero near t ∼ −0.1 (GeV/c)2: this is in agreement with the usual explanation of the crossover phenomena in KN and NN elastic scattering, but in contradiction with the behaviour of the ω-residue functions deduced from other reactions.

Lorentz expansion for the Veneziano amplitude

Abstract The Veneziano amplitude is projected on the irreducible representations of the Lorentz group. An infinite sequence of Toller poles, as well as an essential singularity as λ→∞, is shown to be present. Fixed poles at the non positive integers are also present. The residues of the Toller poles, with the exception of the first, do not factorize.

Neutral non strange 0− meson photoproduction and Regge poles

Abstract Photoproduction of neutral non strange 0 − mesons is considered in the framework of Regge theory. Symmetry relations between coupling constants are widely used. The results are in good agreement with the available experimental data.

Minimal solutions to the conspiracy problem and classification of Regge-pole families. - II

SummaryA non group-theoretical approach to the conspiracy problem, based on analyticity, crossing symmetry and factorization, is presented. The solutions to all the physically interesting cases are given. A classification of Regge-pole families is deduced.RiassuntoSi presenta un approccio non gruppistico al problema delle cospirazioni, basato sulle proprietà di analiticità, simmetria di cressing e fattorizzazione. Si determinano le soluzioni per tutti i casi di interesse fisico e si deduce una classificazione per le famiglie di poli di Regge.Реэумепредлагается не теоретико-групповои подход к проблеме конспиративности, основанныи на аналитичности, кроссинг-симметрии и факториэации. получаутся рещения для всех фиэически интересных случаев. проводится лкасси-фикация семеиств полусов редзе.

Regge pole families and Toller poles: t not equal to 0

Mass formulae for M = 0 and M = 1 Toller families are derived using the standard tools of the S-matrix theory.