• Open Access

Simulation assisted likelihood-free anomaly detection

Anders Andreassen, Benjamin Nachman, and David Shih
Phys. Rev. D 101, 095004 – Published 6 May 2020

Abstract

Given the lack of evidence for new particle discoveries at the Large Hadron Collider (LHC), it is critical to broaden the search program. A variety of model-independent searches have been proposed, adding sensitivity to unexpected signals. There are generally two types of such searches: those that rely heavily on simulations and those that are entirely based on (unlabeled) data. This paper introduces a hybrid method that makes the best of both approaches. For potential signals that are resonant in one known feature, this new method first learns a parametrized reweighting function to morph a given simulation to match the data in sidebands. This function is then interpolated into the signal region, and then the reweighted background-only simulation can be used for supervised learning as well as for background estimation. The background estimation from the reweighted simulation allows for nontrivial correlations between features used for classification and the resonant feature. A dijet search with jet substructure is used to illustrate the new method. Future applications of Simulation Assisted Likelihood-free Anomaly Detection (salad) include a variety of final states and potential combinations with other model-independent approaches.

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  • Received 9 February 2020
  • Accepted 13 April 2020

DOI:https://doi.org/10.1103/PhysRevD.101.095004

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.

Published by the American Physical Society

Physics Subject Headings (PhySH)

Particles & Fields

Authors & Affiliations

Anders Andreassen1,*, Benjamin Nachman2,†, and David Shih2,3,4,‡

  • 1Google, Mountain View, California 94043, USA
  • 2Physics Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
  • 3NHETC, Department of Physics and Astronomy, Rutgers, Piscataway, New Jersey 08854, USA
  • 4Berkeley Center for Theoretical Physics, University of California, Berkeley, California 94720, USA

  • *ajandreassen@google.com
  • bpnachman@lbl.gov
  • shih@physics.rutgers.edu

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Vol. 101, Iss. 9 — 1 May 2020

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