Simplified Models for LHC New Physics Searches

TL;DR

This paper introduces simplified models for LHC new physics searches, providing a framework that links theoretical parameters to collider observables, aiding in the design and interpretation of experimental results, especially for early data.

Contribution

It formalizes the use of simplified models with effective Lagrangians for LHC searches, encouraging their broader adoption by ATLAS and CMS to improve new physics characterization.

Findings

Defines simplified models with effective Lagrangians and key parameters.

Provides a set of representative models for early LHC data analysis.

Summarizes workshop results and offers future development suggestions.

Abstract

This document proposes a collection of simplified models relevant to the design of new-physics searches at the LHC and the characterization of their results. Both ATLAS and CMS have already presented some results in terms of simplified models, and we encourage them to continue and expand this effort, which supplements both signature-based results and benchmark model interpretations. A simplified model is defined by an effective Lagrangian describing the interactions of a small number of new particles. Simplified models can equally well be described by a small number of masses and cross-sections. These parameters are directly related to collider physics observables, making simplified models a particularly effective framework for evaluating searches and a useful starting point for characterizing positive signals of new physics. This document serves as an official summary of the results from the "Topologies for Early LHC Searches" workshop, held at SLAC in September of 2010, the purpose of which was to develop a set of representative models that can be used to cover all relevant phase space in experimental searches. Particular emphasis is placed on searches relevant for the first ~50-500 pb-1 of data and those motivated by supersymmetric models. This note largely summarizes material posted at http://lhcnewphysics.org/, which includes simplified model definitions, Monte Carlo material, and supporting contacts within the theory community. We also comment on future developments that may be useful as more data is gathered and analyzed by the experiments.