skip to main content


Title: Using sorted invariant mass variables to evade combinatorial ambiguities in cascade decays

The classic method for mass determination in a SUSY-like cascade decay chain relies on measurements of the kinematic endpoints in the invariant mass distributions of suitable collections of visible decay products. However, the procedure is complicated by combinatorial ambiguities: e.g., the visible final state particles may be indistinguishable (as in the case of QCD jets), or one may not know the exact order in which they are emitted along the decay chain. In order to avoid such combinatorial ambiguities, we propose to treat the nal state particles fully democratically and consider the sorted set of the invariant masses of all possible partitions of the visible particles in the decay chain. In particular, for a decay to N visible particles, one considers the sorted sets of all possible n-body invariant mass combinations (2≤ n≤ N) and determines the kinematic endpoint m(n,r)max of the distribution of the r-th largest n-body invariant mass m(n,r) for each possible value of n and r. For the classic example of a squark decay in supersymmetry, we provide analytical formulas for the interpretation of these endpoints in terms of the underlying physical masses. We point out that these measurements can be used to determine the structure ofmore » the decay topology, e.g., the number and position of intermediate on-shell resonances.« less
 [1] ;  [1] ;  [2]
  1. Univ. of Florida, Gainesville, FL (United States). Physics Dept.
  2. Inst. of Basic Science, Daejeon (Korea, Republic of). Center for Theoretical Physics of the Universe
Publication Date:
OSTI Identifier:
Grant/Contract Number:
SC0010296; PHY-0969510
Accepted Manuscript
Journal Name:
Journal of High Energy Physics (Online)
Additional Journal Information:
Journal Name: Journal of High Energy Physics (Online); Journal Volume: 2016; Journal Issue: 2; Journal ID: ISSN 1029-8479
Springer Berlin
Research Org:
Univ. of Florida, Gainesville, FL (United States)
Sponsoring Org:
USDOE Office of Science (SC); National Science Foundation (NSF)
Country of Publication:
United States
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS Deep Inelastic Scattering (Phenomenology)