In December of last year, scientists at the Large Hadron Collider in Europe announced startling results hinting at the existence of an undiscovered subatomic particle—one with a mass six times heavier than the Higgs boson, the particle that made headlines in 2012. The evidence is still thin, but if more data confirm the finding, it could sharpen humankind's understanding of the building blocks of the universe. "This was a very surprising announcement and a puzzle at the same time, because the lifetime and mass of the particle could reveal something else beyond simply one extra particle, if it turns out to be a real signal," said Kyoungchul "K.C." Kong, associate professor of physics and astronomy at the University of Kansas. "Yet we do not claim this as a discovery, and we need more data." Based on the LHC findings, theoretical physicists around the world rushed to offer ideas that could explain the mystery signal and guide further experimentation. Physical Review Letters, the leading peer-reviewed journal in the field, received hundreds of papers purporting to illuminate the LHC results. "We explore ideas," Kong said of theoretical particle physicists. "Probably most of ideas are wrong—but we learn from them, and we propose better ideas." Read more at: http://phys.org/news/2016-07-physicist-theory-mysterious-large-hadron.html#jCp
http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.151805 750 GeV Diphoton Excess May Not Imply a 750 GeV Resonance: ABSTRACT We discuss nonstandard interpretations of the 750 GeV diphoton excess recently reported by the ATLAS and CMS Collaborations which do notinvolve a new, relatively broad resonance with a mass near 750 GeV. Instead, we consider the sequential cascade decay of a much heavier, possibly quite narrow, resonance into two photons along with one or more additional particles. The resulting diphoton invariant mass signal is generically rather broad, as suggested by the data. We examine three specific event topologies—the “antler,” the “sandwich,” and the two-step cascade decay—and show that they all can provide a good fit to the observed published data. In each case, we delineate the preferred mass parameter space selected by the best fit. In spite of the presence of extra particles in the final state, the measured diphoton pT spectrum is moderate due to its anticorrelation with the diphoton invariant mass. We comment on the future prospects of discriminating with higher statistics between our scenarios, as well as from more conventional interpretations.