On the ΣN cusp in the pp → pK+Λ reaction

S. Abd El-Samad; E. Borodina; K. -Th. Brinkmann; H. Clement; E. Doroshkevich; R. Dzhygadlo; K. Ehrhardt; A. Erhardt; W. Eyrich; H. Freiesleben; W. Gast; A. Gillitzer; D. Grzonka; C. Hanhart; F. Hauenstein; P. Klaja; K. Kilian; M. Krapp; J. Ritman; E. Roderburg; M. Röder; M. Schulte-Wissermann; W. Schroeder; T. Sefzick; G. J. Wagner; P. Wintz; P. Wüstner

doi:10.1140/epja/i2013-13041-8

EPJ

On the ΣN cusp in the pp → pK⁺Λ reaction

COSY-TOF Collaboration
S. Abd El-Samad¹⁹⁸⁷¹, E. Borodina²⁹⁸⁷¹^,39871, K. -Th. Brinkmann⁴⁹⁸⁷¹, H. Clement⁵⁹⁸⁷¹^,69871^*, E. Doroshkevich⁵⁹⁸⁷¹^,69871, R. Dzhygadlo²⁹⁸⁷¹^,39871, K. Ehrhardt⁵⁹⁸⁷¹^,69871, A. Erhardt⁵⁹⁸⁷¹^,69871, W. Eyrich⁷⁹⁸⁷¹, H. Freiesleben⁸⁹⁸⁷¹, W. Gast²⁹⁸⁷¹^,39871, A. Gillitzer²⁹⁸⁷¹^,39871, D. Grzonka²⁹⁸⁷¹^,39871, C. Hanhart²⁹⁸⁷¹^,39871^,99871, F. Hauenstein²⁹⁸⁷¹^,39871^,79871, P. Klaja²⁹⁸⁷¹^,39871^,79871, K. Kilian²⁹⁸⁷¹^,39871, M. Krapp⁷⁹⁸⁷¹, J. Ritman²⁹⁸⁷¹^,39871, E. Roderburg²⁹⁸⁷¹^,39871, M. Röder²⁹⁸⁷¹^,39871, M. Schulte-Wissermann⁷⁹⁸⁷¹, W. Schroeder²⁹⁸⁷¹^,39871^,79871^,a, T. Sefzick²⁹⁸⁷¹^,39871, G. J. Wagner⁵⁹⁸⁷¹^,69871, P. Wintz²⁹⁸⁷¹^,39871 and P. Wüstner²⁹⁸⁷¹^,39871^,109871

¹⁹⁸⁷¹ Atomic Energy Authority NRC Cairo, Cairo, Egypt
²⁹⁸⁷¹ Institut für Kernphysik, Forschungszentrum Jülich, D-52428, Jülich, Germany
³⁹⁸⁷¹ Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52428, Jülich, Germany
⁴⁹⁸⁷¹ Physikalisches Institut Justus-Liebig-Universität, D-35392, Gießen, Germany
⁵⁹⁸⁷¹ Physikalisches Institut der Universität Tübingen, Tübingen, Germany
⁶⁹⁸⁷¹ Kepler Center for Astro and Particle Physics, University of Tübingen, Auf der Morgenstelle 14, D-72076, Tübingen, Germany
⁷⁹⁸⁷¹ Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058, Erlangen, Germany
⁸⁹⁸⁷¹ Institut für Kern- und Teilchenphysik, Technische Universität Dresden, D-01062, Dresden, Germany
⁹⁹⁸⁷¹ Institute for Advanced Simulation, Forschungszentrum Jülich, D-52428, Jülich, Germany
¹⁰⁹⁸⁷¹ Zentralinstitut für Elektronik, Forschungszentrum Jülich, D-52428, Jülich, Germany

Received: 20 November 2012
Revised: 22 February 2013
Accepted: 26 February 2013
Published online: 27 March 2013

Abstract

Measurements of the pp → pK ⁺ Λ reaction at T _p = 2.28 GeV have been carried out at COSY-TOF. In addition to the Λp FSI and N ^* resonance excitation effects a pronounced narrow structure is observed in the Dalitz plot and in its projection on the pΛ invariant mass. The strongly asymmetric structure appears at the pp → NK ⁺ Σ threshold and is interpreted as the ΣN cusp effect. The observed width of about 20 MeV/c ² is substantially broader than anticipated from previous measurements as well as theoretical predictions. Angular distributions of this cusp structure are shown to be dissimilar to those in the residual pK ⁺ Λ channel, but similar to those observed in the pK ⁺ Σ ⁰ channel.

Present address: Forschungszentrum Jülich, D-52428, Jülich, Germany

15th European Conference on Atoms Molecules and Photons (ECAMP)
June 30 to July 4, 2025
Innsbruck, Austria

EPJ

On the ΣN cusp in the pp → pK+Λ reaction

Conference announcements

On the ΣN cusp in the pp → pK⁺Λ reaction