Determination of the <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>π</mi></mrow><mrow><mo>±</mo></mrow></msup></mrow><mi mathvariant="italic">p</mi><mspace></mspace><mo>→</mo><mrow><msup><mrow><mi>π</mi></mrow><mrow><mo>±</mo></mrow></msup></mrow><mrow><msup><mrow><mi>π</mi></mrow><mrow><mo>+</mo></mrow></msup></mrow><mi mathvariant="italic">n</mi></math></span> Cross Section Near Threshold

J. B. Lange; F. Duncan; A. Ambardar; A. Feltham; G. Hofman; R. R. Johnson; G. Jones; M. Pavan; K. J. Raywood; D. Vetterli; J. T. Brack; D. Ottewell; G. R. Smith; M. E. Sevior

doi:10.1103/PhysRevLett.80.1597

Determination of the $π^{\pm} p \to π^{\pm} π^{+} n$ Cross Section Near Threshold

J. B. Lange, F. Duncan, A. Ambardar, A. Feltham, G. Hofman, R. R. Johnson, G. Jones, M. Pavan, K. J. Raywood, D. Vetterli, J. T. Brack, D. Ottewell, G. R. Smith, and M. E. Sevior

Phys. Rev. Lett. 80, 1597 – Published 23 February 1998

Abstract

The total cross section for the $π^{-} p \to π^{-} π^{+} n$ reaction has been measured at incident pion kinetic energies of 200, 190, 184, and 180 MeV. In addition, the $π^{+} p \to π^{+} π^{+} n$ reaction was measured at 200 and 184 MeV. A fit of the cross sections by heavy baryon chiral perturbation theory yields values of $8.5 \pm 0.6 (m_{π}^{- 3})$ and $2.5 \pm 0.1 (m_{π}^{- 3})$ for the reaction matrix elements $A_{10}$ and $A_{32}$ , which correspond to values for the $s$ -wave isospin-0 and isospin-2 $π - π$ scattering lengths of $a_{0} = 0.23 \pm 0.08 (m_{π}^{- 1})$ and $a_{2} = - 0.031 \pm 0.008 (m_{π}^{- 1})$ , respectively.

Received 22 September 1997

DOI:https://doi.org/10.1103/PhysRevLett.80.1597

Authors & Affiliations

J. B. Lange, F. Duncan^*, A. Ambardar, A. Feltham, G. Hofman, R. R. Johnson, G. Jones, M. Pavan^†, K. J. Raywood, and D. Vetterli^‡

Department of Physics, University of British Columbia, Vancouver, British Columbia, V6T 1Z1, Canada

J. T. Brack^§, D. Ottewell, and G. R. Smith

TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, V66T 2A3, Canada

M. E. Sevior^∥

School of Physics, University of Melbourne, Parkville, Victoria, 3052, Austalia

^*Present address: Department of Physics, Queen's University, Kingston, ON, K7L 3N6 Canada.
^†Present address: M.I.T., Cambridge, MA 02139.
^‡Present address: Inselspital, University of Bern, Division of Medical Radiation Physics, CH-3010 Bern, Switzerland.
^§Present address: Department of Physics, University of Colorado at Boulder, Boulder, CO 80309-0390.
^∥Electronic address: msevior@physics.unimelb.edu.au