A model explaining neutrino masses and the DAMPE cosmic ray electron excess

Yi-Zhong Fan,Wei-Chih Huang,Martin Spinrath,Yue-Lin Sming Tsai,Qiang Yuan

doi:10.1016/j.physletb.2018.03.066

Abstract

We propose a flavored U(1)eμ neutrino mass and dark matter (DM) model to explain the recent DArk Matter Particle Explorer (DAMPE) data, which feature an excess on the cosmic ray electron plus positron flux around 1.4 TeV. Only the first two lepton generations of the Standard Model are charged under the new U(1)eμ gauge symmetry. A vector-like fermion ψ, which is our DM candidate, annihilates into e± and μ± via the new gauge boson Z′ exchange and accounts for the DAMPE excess. We have found that the data favors a ψ mass around 1.5 TeV and a Z′ mass around 2.6 TeV, which can potentially be probed by the next generation lepton colliders and DM direct detection experiments.

Highlights

THE MODELOur model is a rather minimal extension of the standard model (SM). We add one additional anomaly-free U(1)eμ gauge group, two additional scalars, φ1 and φ2, whose vacuum expectation values (vevs) break the new U(1)eμ spontaneously, three right-handed neutrinos, and a vector-like fermion ψ as a dark matter (DM) candidate
The newly released data from the DArk Matter Particle Explorer (DAMPE [1]) exhibits an intriguing excess of the cosmic ray electron plus positron flux at energies around 1.4 TeV [2]
We propose a simple U(1)eμ flavored neutrino mass model inspired by the DAMPE e+ + e− excess at energies around 1.4 TeV [2]

Summary

THE MODEL

Our model is a rather minimal extension of the SM. We add one additional anomaly-free U(1)eμ gauge group, two additional scalars, φ1 and φ2, whose vacuum expectation values (vevs) break the new U(1)eμ spontaneously, three right-handed neutrinos, and a vector-like fermion ψ as a DM candidate. Right-handed leptons and neutrinos of the first two TABLE I: Charge assignments of the fields under the new U(1)eμ gauge group which is broken by the vevs of the scalar fields φ1 and φ2. The fermion ψ is our DM candidate These three new fields do not carry any SM quantum numbers and all the SM fields not shown are neutral under U(1)eμ. In this model, the U(1)eμ symmetry demands both the charged lepton and the neutrino Yukawa couplings to be diagonal in the flavor basis. Where yi j are Yukawa couplings of the right-handed neutrinos with the scalar singlets φ1 and φ2, and M12 and M3 are mass parameters. The total Z decay width into ff and ψψ reads

PARAMETER SPACE

OTHER CONSTRAINTS AND PROSPECTS

CONCLUSION