Model Choice and Crucial Tests. On the Empirical Epistemology of the Higgs Discovery

TL;DR

This paper examines the epistemic attitudes of physicists regarding the Higgs boson discovery, highlighting its unexpected nature, the dual strategy in analysis, and the philosophical implications for scientific confirmation and theory choice.

Contribution

It provides an empirical analysis of physicists' epistemic attitudes and strategies during the Higgs discovery, linking experimental practices to philosophical concepts of confirmation and underdetermination.

Findings

Physicists were less certain about the Higgs than commonly thought.

The discovery was treated as a crucial experiment confirming the Higgs.

Criteria for theory choice involve epistemic and pragmatic values.

Abstract

Our paper discusses the epistemic attitudes of particle physicists on the discovery of the Higgs boson at the Large Hadron Collider (LHC). It is based on questionnaires and interviews made shortly before and shortly after the discovery in 2012. We show, to begin with, that the discovery of a Standard Model (SM) Higgs boson was less expected than is sometimes assumed. Once the new particle was shown to have properties consistent with SM expectations - albeit with significant experimental uncertainties -, there was a broad agreement that 'a' Higgs boson had been found. Physicists adopted a twopronged strategy. On the one hand, they treated the particle as a SM Higgs boson and tried to establish its properties with higher precision; on the other hand, they searched for any hints of physics beyond the SM. This motivates our first philosophical thesis: the Higgs discovery, being of fundamental importance and establishing a new kind of particle, represented a crucial experiment if one interprets this notion in an appropriate sense. By embedding the LHC into thetradition of previous precision experiments and the experimental strategies thus established, Duhemian underdetermination is kept at bay. Second, our case study suggests that criteria of theory (or model) preference should be understood as epistemic and pragmatic values that have to be weighed in factual research practice. The Higgs discovery led to a shift from pragmatic to epistemic values as regards the mechanisms of electroweak symmetry breaking. Complex criteria, such as naturalness, combine epistemic and pragmatic values, but are coherently applied by the community.