Widening the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"><mml:mi>U</mml:mi><mml:msub><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mn>1</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi>L</mml:mi></mml:mrow><mml:mrow><mml:mi>μ</mml:mi></mml:mrow></mml:msub><mml:mo linebreak="badbreak" linebreakstyle="after">−</mml:mo><mml:msub><mml:mrow><mml:mi>L</mml:mi></mml:mrow><mml:mrow><mml:mi>τ</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:msub></mml:math> Z′ mass range for resolving the muon g − 2 anomaly
Yu Cheng, Xiao-Gang He, J. F. Sun
Abstract
Exchanging a Z′ gauge boson is a favored mechanism to solve the muon (g−2)μ anomaly. Among such models the Z′ from U(1)Lμ−Lτ gauge group has been extensively studied. In this model the same interaction addressing (g−2)μ, leads to an enhanced muon neutrino trident (MNT) process νμN→νμμμ¯N constraining the Z′ mass to be less than a few hundred MeV. Many other Z′ models face the same problem. It has long been realized that the coupling of Z′ in the model can admit (μ¯γμτ+ν¯μγμLντ)Zμ′ interaction which does not contribute to the MNT process. It can solve (g−2)μ anomaly for a much wider Z′ mass range. However this new interaction induces τ→μν¯μντ which rules out it as a solution to (g−2)μ anomaly. Here we propose a mechanism by introducing type-II seesaw SU(2)L triplet scalars to evade constraints from all known data to allow a wide Z′ mass range to solve the (g−2)μ anomaly. This mechanism opens a new window for Z′ physics.