Search for Branons at LEP

TL;DR

This paper searches for evidence of brane fluctuations called branons in electron-positron collisions at LEP, setting lower mass limits and excluding certain brane tension scenarios based on the absence of excess events.

Contribution

It provides the first experimental constraints on branon properties in the context of extra-dimensional theories using LEP data.

Findings

No excess events observed over Standard Model predictions.

Lower branon mass limit set at 103 GeV for small brane tensions.

Brane tensions below 180 GeV are excluded for light branons.

Abstract

We search, in the context of extra-dimension scenarios, for the possible existence of brane fluctuations, called branons. Events with a single photon or a single Z-boson and missing energy and momentum collected with the L3 detector in e^+ e^- collisions at centre-of-mass energies sqrt{s}=189-209$ GeV are analysed. No excess over the Standard Model expectations is found and a lower limit at 95% confidence level of 103 GeV is derived for the mass of branons, for a scenario with small brane tensions. Alternatively, under the assumption of a light branon, brane tensions below 180 GeV are excluded.