SOME IMPLICATIONS OF A NEW SOURCE OF COSMIC-RAY MUONS

We study implications of the recent experiment by the University of Utah cosmic-ray group, which presents evidence for a new source of cosmic-ray muons. The data imply the existence of a new class of hadrons X, produced in pairs with a cross section 0.3 mb in primary cosmic-ray collisions of energy >1012-1013 eV. The X, although stable under strong and electromagnetic interactions, decays with large branching ratio into states containing a muon and with lifetime <10-7-10-8 sec. The total mass of the produced X pair is estimated to be less than 55 GeV. We examine the possible quantum numbers of X. We study possible new interactions of cosmic-ray muons and neutrinos underground. In particular, the muon electromagnetic field should photoproduce X; the cross section for this process is estimated to be ∼10-32 cm2 and may lead to observation of pairs of muons under ground with small lateral separation or measurable angular divergence. The hypothesis X=W=intermediate boson for the weak interactions is considered; the experimental limits on the production of W by neutrinos and muons underground, along the with absence of large ν-p elastic scattering at accelerator energies, place strong, and possibly fatal, constraints on this interpretation. The importance of the polarization of the muon beam underground in these considerations is pointed out. Finally, further experimental consequences of the existence of X are discussed. © 1969 The American Physical Society.