April 1, 2012
Complex software models are used to understand the results from the Large Hadron Collider.
These include simulations of the particle physics in the proton-proton collisions, as well as of the material and geometry of the detectors and the strength of the various magnetic fields. As more data are accumulated, the required precision of this software increases.
A recent review recommended that the number of decimal places used to represent numbers in the software should be increased. This means all mathematical constants such as e and pi, as well as physical constants and the measured dimensions of the detectors. So far, so routine. But when adding more precision to pi, a strange effect was noticed.
The alignment of charged particle tracks across detector boundaries actually got worse when a more precise value was used. In addition, the agreement between simulation and data also got slightly worse.