Search for Nearly Mass-Degenerate Higgsinos Using Low-Momentum Mildly Displaced Tracks in pp Collisions at sqrts=13  TeV with the ATLAS Detector

• Published in: Physical review letters 2024-05, Vol.132 (22), p.221801
• Main Authors: Addison, M J, Alfonsi, F, Allbrooke, B M M, Aly, M, Angerami, A, Anulli, F, Badea, A, Balz, J, Bhattacharya, D S, Bogdanchikov, A G, Bohm, C, Bruschi, M, Carnelli, A, Catmore, J R, Chen, Y, Cindro, V, Coccaro, A, Cowan, G, Damp, J, Demichev, M, Desch, K, Dias, F A, Dimitriadi, C, Draguet, M A, Earnshaw, Z O, Ellinghaus, F, Errenst, M, Evans, L S, Ferguson, R A M, mica, A, ti, A C, Gallop, B J, Gan, K K, Giugliarelli, G, Guhit, J A M, Han, J, Hasegawa, Y, Hawkes, C M, Hellman, S, Huebner, M, Jinnouchi, O, Juste Rozas, A, Kalaitzidou, I, Kang, N J, Keeler, R, Kremer, J A, Kuesters, R, Kurova, A, Liberatore, M, Lohse, T, Loiacono, E, Lu, S, Luehring, F, Ma, H, Mac Donell, D M, Mali, M, Mallik, U, Mckenzie, R P, Min, T, Morinaga, M, Nicolaidou, R, Niemeyer, M, Palacino, G, Park, K R, Pettersson, N E, Prokofiev, K, Puddefoot, J E, Ramakoti, E, Rebuzzi, D M, Rej, A, Reynolds, E, Richter-Was, E, Riedler, P, Sandoval, C, Schwienhorst, R, Shahinian, J D, Sheppard, D J, Shipsey, I P J, Shojaii, J, Simion, S, Singh, S, Stavropoulos, G, Tafoya Vargas, J S, Tanasini, M, Tikhonov, Yu A, Ting, E X L, Torró Pastor, E, Tost, M, Vachon, B, Varouchas, D, Wada, S, Wang, X, Warrack, N, Williams, H H, Wu, Z, Xin, S, Yacoob, S, Yan, S, Yang, H J, Zhou, N
• Format: Article
• Language: English
• ISSN: 1079-7114; 1079-7114
• DOI: 10.1103/PhysRevLett.132.221801

Higgsinos with masses near the electroweak scale can solve the hierarchy problem and provide a dark matter candidate, while detecting them at the LHC remains challenging if their mass splitting is O(1  GeV). This Letter presents a novel search for nearly mass-degenerate Higgsinos in events with an energetic jet, missing transverse momentum, and a low-momentum track with a significant transverse impact parameter using 140  fb^{-1} of proton-proton collision data at sqrt[s]=13  TeV collected by the ATLAS experiment. For the first time since LEP, a range of mass splittings between the lightest charged and neutral Higgsinos from 0.3 to 0.9 GeV is excluded at 95% confidence level, with a maximum reach of approximately 170 GeV in the Higgsino mass.Higgsinos with masses near the electroweak scale can solve the hierarchy problem and provide a dark matter candidate, while detecting them at the LHC remains challenging if their mass splitting is O(1  GeV). This Letter presents a novel search for nearly mass-degenerate Higgsinos in events with an energetic jet, missing transverse momentum, and a low-momentum track with a significant transverse impact parameter using 140  fb^{-1} of proton-proton collision data at sqrt[s]=13  TeV collected by the ATLAS experiment. For the first time since LEP, a range of mass splittings between the lightest charged and neutral Higgsinos from 0.3 to 0.9 GeV is excluded at 95% confidence level, with a maximum reach of approximately 170 GeV in the Higgsino mass.