Stops and E/T: The shape of things to come

Journal Article · Tue May 01 04:00:00 EDT 2012 · Physical Review. D, Particles, Fields, Gravitation and Cosmology

DOI:https://doi.org/10.1103/PhysRevD.87.035016· OSTI ID:1155795

Alves, Daniele S.M. ^[1]; Buckley, Matthew R. ^[1]; Fox, Patrick J. ^[1]; Lykken, Joseph D. ^[1]; Yu, Chiu-Tien ^[2]

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1. Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
2. Univ. of Wisconsin-Madison, Madison, WI (United States)

LHC experiments have placed strong bounds on the production of supersymmetric colored particles (squarks and gluinos), under the assumption that all flavors of squarks are nearly degenerate. However, the current experimental constraints on stop squarks are much weaker, due to the smaller production cross section and difficult backgrounds. While light stops are motivated by naturalness arguments, it has been suggested that such particles become nearly impossible to detect near the limit where their mass is degenerate with the sum of the masses of their decay products. We show that this is not the case, and that searches based on missing transverse energy (MET) have significant reach for stop masses above 175 GeV, even in the degenerate limit. We consider direct pair production of stops, decaying to invisible LSPs and tops with either hadronic or semi-leptonic final states. Modest intrinsic differences in MET are magnified by boosted kinematics and by shape analyses of MET or suitably-chosen observables related to MET. For these observables we show that the distributions of the relevant backgrounds and signals are well-described by simple analytic functions, in the kinematic regime where signal is enhanced. Shape analyses of MET-related distributions will allow the LHC experiments to place significantly improved bounds on stop squarks, even in scenarios where the stop-LSP mass difference is degenerate with the top mass. Assuming 20/fb of luminosity at 8 TeV, we conservatively estimate that experiments can exclude or discover degenerate stops with mass as large as ~ 360 GeV and 560 GeV for massless LSPs.

• Research Organization: Fermi National Accelerator Laboratory (FNAL), Batavia, IL
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
• DOE Contract Number: AC02-07CH11359
• OSTI ID: 1155795
• Report Number(s): FERMILAB-PUB-12-250-A-T; arXiv eprint number arXiv:1205.5805
• Journal Information: Physical Review. D, Particles, Fields, Gravitation and Cosmology, Journal Name: Physical Review. D, Particles, Fields, Gravitation and Cosmology Journal Issue: 3 Vol. 87; ISSN 1550-7998
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS