Loophole in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>K</mml:mi><mml:mo stretchy="false">→</mml:mo><mml:mi>π</mml:mi><mml:mi>ν</mml:mi><mml:mover accent="true"><mml:mrow><mml:mi>ν</mml:mi></mml:mrow><mml:mrow><mml:mo stretchy="false">¯</mml:mo></mml:mrow></mml:mover></mml:mrow></mml:math>Search and New Weak Leptonic Forces

Abstract

Weakly interacting K→πX(0) emission with mX(0)≅mπ(0) is out of sight of the current K+→π+ νν study, but it can be sensed by the KL→π(0)νν search. This evades the usual Grossman-Nir bound of B(KL→π(0)νν)<1.4×10(-9); thus, the KOTO experiment is already starting to probe new physics. An intriguing possibility is the Z' gauge boson of a weak leptonic force that couples to Lμ-Lτ (the difference between the muon and tauon numbers), which may explain the long-standing "muon g-2" anomaly, but is constrained by νμN→νμNμ+ μ- scattering to mZ'≲400 MeV. An explicit model for K→πZ' is given, which illustrates the link between rare kaon and B→Kμ+ μ-, K(*)νν decays. Complementary to these searches and future lepton experiments, the LHC might discover the scalar boson ϕ responsible for light mZ' generation via ϕ→Z'Z'→2(μ+ μ-).

Locations

• Physical Review Letters - View
• arXiv (Cornell University) - View - PDF
• PubMed - View
• DataCite API - View