Search for charginos nearly mass degenerate with the lightest neutralino based on a disappearing-track signature in pp collisions at √(s)=8 TeV with the ATLAS detector

Aad, G. and Abajyan, T. and Abbott, B. and Abdallah, J. and Abdel, Khalek S. and Abdinov, O. and Aben, R. and Abi, B. and Abolins, M. and Abouzeid, O. S. and Abramowicz, H. and Abreu, H. and Abulaiti, Y. and Acharya, B. S. and Adamczyk, L. and Adams, D. L. and Addy, T. N. and Adelman, J. and Adomeit, S. and Adye, T. and Aefsky, S. and Agatonovic-Jovin, T. and Aguilar-Saavedra, J. A. and Agustoni, M. and Ahlen, S. P. and Ahmad, A. and Ahmadov, F. and Ahsan, M. and Aielli, G. and Åkesson, T. P. A. and Krasznahorkay, Attila and Nagai, Yoshikazu and Pásztor, Gabriella and Tóth, József (2013) Search for charginos nearly mass degenerate with the lightest neutralino based on a disappearing-track signature in pp collisions at √(s)=8 TeV with the ATLAS detector. PHYSICAL REVIEW D, 88 (11). ISSN 2470-0010

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Abstract

A search is presented for direct chargino production based on a disappearing-track signature using 20.3 fb−1 of proton–proton collisions at √ s = 8 TeV collected with the ATLAS experiment at the LHC. In anomaly-mediated supersymmetry breaking (AMSB) models, the lightest chargino is nearly mass-degenerate with the lightest neutralino and its lifetime is long enough to be detected in the tracking detectors by identifying decays that result in tracks with no associated hits in the outer region of the tracking system. Some models with supersymmetry also predict charginos with a significant lifetime. This analysis attains sensitivity for charginos with a lifetime between 0.1 ns and 10 ns, and significantly surpasses the reach of the LEP experiments. No significant excess above the background expectation is observed for candidate tracks with large transverse momentum, and constraints on chargino properties are obtained. In the AMSB scenarios, a chargino mass below 270 GeV is excluded at 95% confidence level.

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