Eur. Phys. J. C (2007) 51: 753
https://doi.org/10.1140/epjc/s10052-007-0367-7

Regular Article - Experimental Physics

Spin analysis of supersymmetric particles

¹ Deutsches Elektronen-Synchrotron DESY, 22603, Hamburg, Germany
² Physics Department and RIPC, Chonbuk National University, Jeonju, 561-756, Korea
³ Theory Division, KEK, Tsukuba, Ibaraki, 305-0801, Japan
⁴ I. Physikalisches Institut, RWTH Aachen, Aachen, Germany
⁵ School of Physics, Korea Institute for Advanced Study, Seoul, 130-722, Korea

^* e-mail: sychoi@chonbuk.ac.kr

Received: 3 January 2006
Revised: 19 June 2007
Published online: 1 August 2007

Abstract

The spin of supersymmetric particles can be determined at e⁺e^- colliders unambiguously. This is demonstrated for a characteristic set of non-colored supersymmetric particles – smuons, selectrons, and charginos/neutralinos. The analysis is based on the threshold behavior of the excitation curves for pair production in e⁺e^- collisions, the angular distribution in the production process and decay angular distributions. In the first step we present the observables in the helicity formalism for the supersymmetric particles. Subsequently we confront the results with corresponding analyses of Kaluza–Klein particles in theories of universal extra space dimensions which behave distinctly different from supersymmetric theories. It is shown in the third step that a set of observables can be designed which signal the spin of supersymmetric particles unambiguously without any model assumptions. Finally in the fourth step it is demonstrated that the determination of the spin of supersymmetric particles can be performed experimentally in practice at an e⁺e^- collider.