Signs of analyticity in fermion scattering

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dc.creatorAdams, Allan
dc.creatorJenkins, Alejandro
dc.creatorO'Connell, Donal
dc.date2008-02-28
dc.date2008-10-31
dc.date.accessioned2026-07-07T10:13:59Z
dc.date.available2026-07-07T10:13:59Z
dc.descriptionWe show that the signs of the leading irrelevant interactions for Dirac fermions are constrained by the analytic structure of the S-matrix. If Regge behavior obtains, negative signs indicate the presence of higher-spin bound states that spoil the convergence of the dispersion integrals and drive the corresponding operators relevant. For nucleon-nucleon scattering, the negativity of some of the low-energy interactions signals the presence of a spin-1 bound state: the deuteron. We connect the divergence of the dispersion integral to the "Sommerfeld enhancement" of the cross-section for low-energy scattering. We also discuss how this illuminates potential pitfalls in using perturbative methods to understand the dependence of the low-energy nuclear interaction on the masses of the light quarks. Finally, we suggest the possibility of applying similar reasoning to the current-current operators in the electroweak effective lagrangian, where no bound states spoil convergence of the dispersion relations.
dc.description23 pages, 5 figures, 2 appendices, preprint format. v3: typos fixed, references improved, discussion significantly extended and clarified (including two new appendices)
dc.identifierhttps://arxiv.org/abs/0802.4081
dc.identifierhttp://arxiv.org/abs/0802.4081
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/172728
dc.subjectHigh Energy Physics - Phenomenology
dc.subjectHigh Energy Physics - Theory
dc.subjectNuclear Theory
dc.titleSigns of analyticity in fermion scattering
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