By Michael Slezak TALK about mixed signals. The Higgs boson’s mass seems to vary depending on how it is measured. What’s more, an oddity in its rate of decay into photons won’t go away. The Large Hadron Collider, part of the CERN laboratory near Geneva, Switzerland, cannot detect the Higgs directly. Instead, its detectors reveal the slew of particles the boson is predicted to decay into. In July, when the discovery of a new boson was announced, the results indicated a mass close to 125 gigaelectronvolts. But at a meeting on 13 December at CERN, Marumi Kado, who works on the LHC’s ATLAS detector, reported a discrepancy: the particle’s decay into photons suggests a mass about 3 GeV greater than the mass suggested by its decay into particles called Z bosons. Albert De Roeck, a Higgs hunter from CMS, ATLAS’s twin detector, finds this puzzling, but suspects it is due to a measurement problem rather than strange physics. The ATLAS team also presented updated results that have been hotly awaited since July. Back then, there were anomalies in the rates at which the new particle decays into photons and into another particle called the tau. If genuine, the anomalies might have yielded clues to enigmas like dark matter, gravity and the universe’s missing antimatter. In November, the tau rate seemed to have stabilised. But according to the latest ATLAS update, the photon rate remains strange – although not enough to be classed as a genuine anomaly. “It keeps us titillated,” says Raymond Volkas from the University of Melbourne in Australia. It keeps us titillated: the photon decay rate is strange, but not enough to be a genuine anomaly The LHC shuts down in early 2013 for an upgrade. Will that let physicists’ blood pressure recover?