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Title: Testing invisible momentum ansatze in missing energy events at the LHC

We consider SUSY-like events with two decay chains, each terminating in an invisible particle, whose true energy and momentum are not measured in the detector. Nevertheless, a useful educated guess about the invisible momenta can still be obtained by optimizing a suitable invariant mass function. We review and contrast several proposals in the literature for such ansatze: four versions of the M T 2-assisted on-shell reconstruction (MAOS), as well as several variants of the on-shell constrained M 2 variables. We compare the performance of these methods with regards to the mass determination of a new particle resonance along the decay chain from the peak of the reconstructed invariant mass distribution. For concreteness, we consider the event topology of dilepton tt¯ events and study each of the three possible subsystems, in both a tt¯ and a SUSY example. We find that the M 2 variables generally provide sharper peaks and therefore better ansatze for the invisible momenta. We show that the performance can be further improved by preselecting events near the kinematic endpoint of the corresponding variable from which the momentum ansatz originates.
 [1] ;  [2] ;  [3] ;  [3]
  1. European Organization for Nuclear Research (CERN), Geneva (Switzerland). Theory Division
  2. Univ. of Florida, Gainesville, FL (United States). Physics Dept.
  3. European Organization for Nuclear Research (CERN), Geneva (Switzerland)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Journal of High Energy Physics (Online)
Additional Journal Information:
Journal Name: Journal of High Energy Physics (Online); Journal Volume: 2017; Journal Issue: 8; Journal ID: ISSN 1029-8479
Springer Berlin
Research Org:
Univ. of Florida, Gainesville, FL (United States); European Organization for Nuclear Research (CERN), Geneva (Switzerland)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Country of Publication:
United States
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; supersymmetry; phenomenology
OSTI Identifier: