Recently the ATLAS and CMS Collaborations have reported evidence of a diphoton excess which may be interpreted as a pseudoscalar boson S with a mass around 750 GeV. To explain the diphoton excess, such a boson is coupled to the Standard Model gauge fields via SFF operators. In this work, we consider the implications of this state for early universe cosmology; in particular, the S field can acquire a large vacuum expectation value due to quantum fluctuations during inflation. During reheating, it then relaxes to its equilibrium value, during which time the same operators introduced to explain the diphoton excess induce a nonzero chemical potential for baryon and lepton number. Interactions such as those involving right-handed neutrinos allow the system to develop a nonzero lepton number and, therefore, this state may also be responsible for the observed cosmological matter-antimatter asymmetry.
Bibliographical noteFunding Information:
A.K. and L.Y. were supported by the U.S. Department of Energy Grant No.DE-SC0009937. A.K. was also supported by the World Premier International Research Center Initiative (WPI), MEXT, Japan. L.P. was partially supported by the Department of Energy Grant No. DE-SC0011842 at the University of Minnesota.