Search for direct top squark pair production in final states with two leptons in $\sqrt{s} = 13$ pp collisions with the ATLAS detector

• Published in: The European physical journal. C, Particles and fields Particles and fields, 2017-12, Vol.77 (12)
• Main Authors: Adersberger, M., Akilli, E., Alexa, C., AmorDosSantos, S. P., Anderson, K. J., Barr, A. J., Bartoldus, R., Batley, J. R., Beltramello, O., Beresford, L., Bertsche, D., Besjes, G. J., Bogdanchikov, A. G., Bortfeldt, J., Bouffard, J., Cakir, O., Caprini, I., Chizhov, M. V., Colombo, T., Conde Muiño, P., Crescioli, F., Cukierman, A. R., Dao, V., Darbo, G., Davey, W., Dita, P., Dolezal, Z., Donati, S., Duschinger, D., Ellajosyula, V., Ferrer, A., Gadatsch, S., Galster, G., Ganguly, S., Gaycken, G., Giannetti, P., Glasman, C., Glatzer, J., Grivaz, J. -F., Heer, S., Howarth, J., Hoya, J., Iwasaki, H., Izen, J. M., Janssen, J., Khramov, E., Kim, H. Y., Klingl, T., Konstantinidis, N., Kordas, K., Krieger, P., Krstic, J., Kukla, R., Kuna, M., Kuprash, O., Kus, V., La Ruffa, F., Lionti, A. E., Lo, C. Y., Lu, H., Luminari, L., Lundberg, O., Lund-Jensen, B., Megy, T. J., Melo, M., Meyer, C., Meyer, J., Mijović, L., Milesi, M., Minegishi, Y., Montalbano, A., Morisbak, V., Nairz, A. M., Neal, H. A., Nektarijevic, S., Noguchi, Y., Perini, L., Plazak, L., Plotnikova, E., Poulsen, T., Rühr, F., Saavedra, A. F., Sammel, D., Sbarra, C., Schaefer, R., Shupe, M. A., Sickles, A. M., Spettel, F., Spousta, M., Tafirout, R., Tanaka, M., Theveneaux-Pelzer, T., Torrence, E., Tsirintanis, N., Tsybychev, D., Tuts, P. M., Vacavant, L., Varvell, K. E., Wilkens, H. G., Zhao, Z.
• Format: Article
• Language: English
• Subjects: PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s10052-017-5445-x

Here, the results of a search for direct pair production of top squarks in events with two opposite-charge leptons (electrons or muons) are reported, using 36.1 fb–1 of integrated luminosity from proton–proton collisions at √s=13 TeV collected by the ATLAS detector at the Large Hadron Collider. To cover a range of mass differences between the top squark t~ and lighter supersymmetric particles, four possible decay modes of the top squark are targeted with dedicated selections: the decay t~→bχ~±1 into a b-quark and the lightest chargino with χ~±1→Wχ~01, the decay t~→tχ~01 into an on-shell top quark and the lightest neutralino, the three-body decay t~→bWχ~01 and the four-body decay t~→bℓνχ~01. No significant excess of events is observed above the Standard Model background for any selection, and limits on top squarks are set as a function of the t~ and χ~01 masses. The results exclude at 95% confidence level t~ masses up to about 720 GeV, extending the exclusion region of supersymmetric parameter space covered by previous searches.