Saturation of the Froissart boundIl Nuovo Cimento A (1965-1970) - Tập 52 - Trang 99-114 - 2008
J. Kupsch, T. P. Pool
Amplitudes for the elastic scattering of two particles are constructed which saturate the Froissart bound and satisfy i) Mandelstam analyticity and polynomial boundedness, ii) crossing symmetry with respect to all channels and iii) inelastic-unitarity constraints.
The conformal symmetry generated by equal-time commutatorsIl Nuovo Cimento A (1965-1970) - Tập 106 - Trang 905-915 - 2008
A. Boresch, K. Landsteiner, O. Piguet, M. Schweda
At the classical level we derive naively from the Ward identity for the conformal symmetry, treated as a diffeomorphism, the equal-time commutator between the improved energy-momentum tensor θ
mn
(y) and the θ
k0(x)-components. The metric field is introduced as an external source for the stress tensor. The analysis is done in the weak-field approximation for the m...... hiện toàn bộ
Universal curve for ππ scattering lengths by optimal extrapolation techniquesIl Nuovo Cimento A (1965-1970) - Tập 38 - Trang 209-222 - 2007
S. Ciulli, D. Treleani, C. Verzegnassi
Using the method of optimal extrapolation to interior points, we re-evaluate the equation of the universal curve of the ππs-wave scattering lengths. We reproduce the gross features of previous determinations, but with a realistic error, without any detailed assumption on the asymptotic behaviour. Possible implications of our result on the numerical value of thep-wave scattering length are qualitat...... hiện toàn bộ
Coherent neutrino scattering—Relativistic and nonrelativisticIl Nuovo Cimento A (1965-1970) - Tập 83 - Trang 263-274 - 2008
P. F. Smith
Coherent detection techniques are being studied both for relativistic neutrinos (e.g. MeV-range solar, orm
υ < 10−4 eV «relic» neutrinos) and for nonrelativistic neutrinos (e.g. 1 eV ... hiện toàn bộ
Current algebra and gauge varianceIl Nuovo Cimento A (1965-1970) - Tập 50 - Trang 129-134 - 2016
J. S. Bell
It is urged that the lesson of gauge invariance in quantum electrodynamics implies the irrelevance of «Schwinger term» difficulties in current algebra. The divergence equations of Veltman form the basis of a gauge-variation formalism in which these questions are avoided. Утверждается, что урок калибровочной инвариантности в квантовой злектродинамике указывает на то, что в алгебре токов трудности «...... hiện toàn bộ
Compton scattering and the couplings of f, ·, ν, A2 and π to photons and nucleonsIl Nuovo Cimento A (1965-1970) - Tập 12 - Trang 21-61 - 2008
J. Baacke, T. H. Chang, H. Kleinert
We use the technique of equating unsubtracted dispersion relations in the forward and backward directions at threshold in order to obtain sum rules for the invariant amplitudes of Compton scattering. Assuming f, ·, ν and π, A2 to dominate the absorptive part of thet-channel, and baryon resonances to saturate the integrals over thes
− andu-channel cuts we are able to express the coupling constants ...... hiện toàn bộ
The constituent quark model: a status reportIl Nuovo Cimento A (1965-1970) - Tập 102 Số 1 - Trang 1-23 - 1989
Godfrey, S.
I review the status of the constituent quark model. I begin by showing that phenomenological heavy-quark potentials are in qualitative agreement with potentials calculated from first principles using the techniques of lattice QCD. I next argue that it is reasonable to extend the constituent quark model to light-quark systems where nonrelativistic approximations are no longer valid. We find that bo...... hiện toàn bộ