Search for direct production of electroweakinos in final states with missing transverse momentum and a Higgs boson decay
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Springer
Received: April 24, 2020 Accepted: September 1, 2020 Published: October 1, 2020
The ATLAS collaboration E-mail: [email protected] Abstract: A search for a chargino-neutralino pair decaying via the 125 GeV Higgs boson into photons is presented. The study is based on the data collected between 2015 and 2018 with the ATLAS detector at the LHC, corresponding to an integrated luminosity of 139 fb−1 of pp collisions at a centre-of-mass energy of 13 TeV. No significant excess over the expected background is observed. Upper limits at 95% confidence level for a massless χ ˜ 01 are set on several electroweakino production cross-sections and the visible cross-section for beyond the Standard Model processes. In the context of simplified supersymmetric models, 95% confidence-level limits of up to 310 GeV in m(χ ˜± ˜02 ), where m(χ ˜01 ) = 0.5 GeV, are 1 /χ ± 0 set. Limits at 95% confidence level are also set on the χ ˜1 χ ˜2 cross-section in the mass plane 0 0 of m(χ ˜± / χ ˜ ) and m( χ ˜ ), and on scenarios with gravitino as the lightest supersymmetric 1 2 1 particle. Upper limits at the 95% confidence-level are set on the higgsino production crosssection. Higgsino masses below 380 GeV are excluded for the case of the higgsino fully decaying into a Higgs boson and a gravitino. Keywords: Hadron-Hadron scattering (experiments) ArXiv ePrint: 2004.10894
Open Access, Copyright CERN, for the benefit of the ATLAS Collaboration. 3 Article funded by SCOAP .
https://doi.org/10.1007/JHEP10(2020)005
JHEP10(2020)005
Search for direct production of electroweakinos in final states with missing transverse momentum and a Higgs boson decaying into photons in pp collisions at √ s = 13 TeV with the ATLAS detector
Contents 1
2 ATLAS detector
3
3 Data and simulation samples
4
4 Event reconstruction
6
5 Event selection 5.1 Baseline selection 5.2 Follow-up selection
9 9 10
6 Signal and background parameterisation
10
7 Systematic uncertainties
11
8 Results 8.1 Limits on the visible cross-section 8.2 Interpretation of the wino-like χ ˜± ˜02 → W ± χ ˜01 hχ ˜01 model 1χ ˜ G ˜ model 8.3 Interpretation of the higgsino-like hGh
14 15 16 17
9 Conclusion
18
The ATLAS collaboration
29
1
Introduction
Theoretical and experimental arguments suggest that the Standard Model (SM) is an effective theory valid up to a certain energy scale. The SM Higgs boson, denoted by h, is observed by the ATLAS and CMS collaborations [1–4]. The Higgs boson mass is strongly sensitive to quantum corrections from physics at very high energy scales and demands a high level of fine-tuning, known as the hierarchy problem [5–8]. Supersymmetry (SUSY) [9–14] resolves the hierarchy problem by introducing, for each known particle state, a new partner (superpartner) that shares the same mass and internal quantum numbers with the exception of spin if supersymmetry is unbroken. However, these superpartners have not been observed, so SUSY must be a broken symmetry and the mass scale of the supersymmetric particles is as yet undetermined. The possibil
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