Abstract
The results of many LHC searches for supersymmetric particles are interpreted using simplified models, in which one fixes the masses and couplings of most sparticles then scans over a few remaining masses of interest. We present a new technique for combining multiple simplified models (that requires no additional simulation) thereby highlighting the utility and limitations of simplified models in general, and demonstrating a simple way of improving LHC search strategies. The technique is used to derive limits on the stop mass that are model independent, modulo some reasonably generic assumptions which are quantified precisely. We find that current ATLAS and CMS results exclude stop masses up to 340 GeV for neutralino masses up to 120 GeV, provided that the total branching ratio into channels other than top-neutralino and bottom-chargino is small, and that there is no mass difference smaller than 10 GeV in the mass spectrum. In deriving these limits we place upper bounds on the branching ratios for complete stop pair decay processes for many values of the stop, neutralino and chargino masses. These are available with this paper.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
S. Akula, M. Liu, P. Nath and G. Peim, Naturalness, Supersymmetry and Implications for LHC and Dark Matter, Phys. Lett. B 709 (2012) 192 [arXiv:1111.4589] [INSPIRE].
B.C. Allanach and B. Gripaios, Hide and Seek With Natural Supersymmetry at the LHC, JHEP 05 (2012) 062 [arXiv:1202.6616] [INSPIRE].
H. Baer, V. Barger, P. Huang and X. Tata, Natural Supersymmetry: LHC, dark matter and ILC searches, JHEP 05 (2012) 109 [arXiv:1203.5539] [INSPIRE].
C. Balázs, A. Buckley, D. Carter, B. Farmer and M. White, Should we still believe in constrained supersymmetry?, Eur. Phys. J. C 73 (2013) 2563 [arXiv:1205.1568] [INSPIRE].
J. Barnard, B. Farmer, T. Gherghetta and M. White, Natural gauge mediation with a bino NLSP at the LHC, Phys. Rev. Lett. 109 (2012) 241801 [arXiv:1208.6062] [INSPIRE].
T. Gherghetta, B. von Harling, A.D. Medina and M.A. Schmidt, The Scale-Invariant NMSSM and the 126 GeV Higgs Boson, JHEP 02 (2013) 032 [arXiv:1212.5243] [INSPIRE].
H. Baer, V. Barger, P. Huang, D. Mickelson, A. Mustafayev et al., Radiatively-driven natural supersymmetry at the LHC, JHEP 12 (2013) 013 [arXiv:1310.4858] [INSPIRE].
J.A. Evans, Y. Kats, D. Shih and M.J. Strassler, Toward Full LHC Coverage of Natural Supersymmetry, arXiv:1310.5758 [INSPIRE].
N. Desai and B. Mukhopadhyaya, Constraints on supersymmetry with light third family from LHC data, JHEP 05 (2012) 057 [arXiv:1111.2830] [INSPIRE].
O. Buchmueller, R. Cavanaugh, A. De Roeck, M.J. Dolan, J.R. Ellis et al., Higgs and Supersymmetry, Eur. Phys. J. C 72 (2012) 2020 [arXiv:1112.3564] [INSPIRE].
P. Bechtle, T. Bringmann, K. Desch, H. Dreiner, M. Hamer et al., Constrained Supersymmetry after two years of LHC data: a global view with Fittino, JHEP 06 (2012) 098 [arXiv:1204.4199] [INSPIRE].
A. Fowlie, M. Kazana, K. Kowalska, S. Munir, L. Roszkowski et al., The CMSSM Favoring New Territories: The Impact of New LHC Limits and a 125 GeV Higgs, Phys. Rev. D 86 (2012) 075010 [arXiv:1206.0264] [INSPIRE].
C. Strege, G. Bertone, F. Feroz, M. Fornasa, R. Ruiz de Austri et al., Global Fits of the CMSSM and NUHM including the LHC Higgs discovery and new XENON100 constraints, JCAP 04 (2013) 013 [arXiv:1212.2636] [INSPIRE].
M.E. Cabrera, J.A. Casas and R.R. de Austri, The health of SUSY after the Higgs discovery and the XENON100 data, JHEP 07 (2013) 182 [arXiv:1212.4821] [INSPIRE].
O. Buchmueller and J. Marrouche, Universal mass limits on gluino and third-generation squarks in the context of Natural-like SUSY spectra, Int. J. Mod. Phys. A 29 (2014) 1450032 [arXiv:1304.2185] [INSPIRE].
K. Kowalska and E.M. Sessolo, Natural MSSM after the LHC 8 TeV run, Phys. Rev. D 88 (2013) 075001 [arXiv:1307.5790] [INSPIRE].
C. Han, K.-i. Hikasa, L. Wu, J.M. Yang and Y. Zhang, Current experimental bounds on stop mass in natural SUSY, JHEP 10 (2013) 216 [arXiv:1308.5307] [INSPIRE].
M.W. Cahill-Rowley, J.L. Hewett, A. Ismail and T.G. Rizzo, More energy, more searches, but the phenomenological MSSM lives on, Phys. Rev. D 88 (2013) 035002 [arXiv:1211.1981] [INSPIRE].
C. Boehm, P.S.B. Dev, A. Mazumdar and E. Pukartas, Naturalness of Light Neutralino Dark Matter in pMSSM after LHC, XENON100 and Planck Data, JHEP 06 (2013) 113 [arXiv:1303.5386] [INSPIRE].
M. Drees, H. Dreiner, D. Schmeier, J. Tattersall and J.S. Kim, CheckMATE: Confronting your Favourite New Physics Model with LHC Data, arXiv:1312.2591 [INSPIRE].
S. Kraml, S. Kulkarni, U. Laa, A. Lessa, W. Magerl et al., SModelS: a tool for interpreting simplified-model results from the LHC and its application to supersymmetry, arXiv:1312.4175 [INSPIRE].
M. Papucci, K. Sakurai, A. Weiler and L. Zeune, Fastlim: a fast LHC limit calculator, arXiv:1402.0492 [INSPIRE].
C. Gutschow and Z. Marshall, Setting limits on supersymmetry using simplified models, arXiv:1202.2662 [INSPIRE].
M.L. Graesser and J. Shelton, Hunting Mixed Top Squark Decays, Phys. Rev. Lett. 111 (2013) 121802 [arXiv:1212.4495] [INSPIRE].
CMS collaboration, Search for top-squark pair production in the single-lepton final state in pp collisions at \( \sqrt{s} \) = 8 TeV, Eur. Phys. J. C 73 (2013) 2677 [arXiv:1308.1586] [INSPIRE].
ATLAS collaboration, Search for direct production of the top squark in the all-hadronic \( t\overline{t}+{E}_T^{miss} \) final state in 21 f b −1 of p-pcollisions at \( \sqrt{s} \) = 8 TeV with the ATLAS detector, ATLAS-CONF-2013-024.
ATLAS collaboration, Search for direct top squark pair production in final states with one isolated lepton, jets and missing transverse momentum in sqrts = 8,TeV pp collisions using 21 fb −1 of ATLAS data, ATLAS-CONF-2013-037.
ATLAS collaboration, Search for direct top squark pair production in final states with two leptons in \( \sqrt{s} \) = 8 TeV pp collisions using 20 f b −1 of ATLAS data., ATLAS-CONF-2013-048.
ATLAS collaboration, Search for direct third-generation squark pair production in final states with missing transverse momentum and two b-jets in \( \sqrt{s} \) = 8 TeV pp collisions with the ATLAS detector, JHEP 10 (2013) 189 [arXiv:1308.2631] [INSPIRE].
A. Djouadi, M.M. Muhlleitner and M. Spira, Decays of supersymmetric particles: The Program SUSY-HIT (SUspect-SdecaY-HDECAY-InTerface), Acta Phys. Polon. B 38 (2007) 635 [hep-ph/0609292] [INSPIRE].
T. Sjöstrand, S. Mrenna and P.Z. Skands, PYTHIA 6.4 Physics and Manual, JHEP 05 (2006) 026 [hep-ph/0603175] [INSPIRE].
T. Sjöstrand, S. Mrenna and P.Z. Skands, A Brief Introduction to PYTHIA 8.1, Comput. Phys. Commun. 178 (2008) 852 [arXiv:0710.3820] [INSPIRE].
N. Desai and P.Z. Skands, Supersymmetry and Generic BSM Models in PYTHIA 8, Eur. Phys. J. C 72 (2012) 2238 [arXiv:1109.5852] [INSPIRE].
W. Beenakker, R. Hopker and M. Spira, PROSPINO: A Program for the production of supersymmetric particles in next-to-leading order QCD, hep-ph/9611232 [INSPIRE].
A.L. Read, Presentation of search results: The CL(s) technique, J. Phys. G 28 (2002) 2693 [INSPIRE].
Open Access
This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.
Author information
Authors and Affiliations
Corresponding author
Additional information
ArXiv ePrint: 1402.3298
Rights and permissions
Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0), which permits use, duplication, adaptation, distribution, and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
About this article
Cite this article
Barnard, J., Farmer, B. A simple technique for combining simplified models and its application to direct stop production. J. High Energ. Phys. 2014, 132 (2014). https://doi.org/10.1007/JHEP06(2014)132
Received:
Revised:
Accepted:
Published:
DOI: https://doi.org/10.1007/JHEP06(2014)132