Unbroken B – L symmetry

By J. Heeck. 2014

186 citations recorded by the source corpus.

Abstract The difference between baryon number B and lepton number L is the only anomaly-free global symmetry of the Standard Model, easily promoted to a local symmetry by introducing three right-handed neutrinos, which automatically make neutrinos massive. The non-observation of any ( B – L ) -violating processes leads us to scrutinize the case of unbroken gauged B–L; besides Dirac neutrinos, the model contains only three parameters, the gauge coupling strength g ′ , the Stuckelberg mass M Z ′ , and the kinetic mixing angle χ. The new force could manifest itself at any scale, and we collect and derive bounds on g ′ over the entire testable range M Z ′ = 0 – 10 13 eV , also of interest for the more popular case of spontaneously broken B–L or other new light forces. We show in particular that successful Big Bang nucleosynthesis provides strong bounds for masses 10 eV M Z ′ 10 GeV due to resonant enhancement of the rate f ¯ f ↔ ν ¯ R ν R . The strongest limits typically arise from astrophysics and colliders, probing scales M Z ′ / g ′ from TeV up to 10 10 GeV .

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/c2978ecf90d707a658bb9568a0e4ae0224f866e5

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In Nuclear and High Energy Physics

1. M. Drewes
2. Tongyan Lin
3. R. Essig
4. M. Shaposhnikov
5. A. Ringwald
6. K. Zurek
7. Alexey Boyarsky
8. Oleg Ruchayskiy

Citations in the corpus

• Stellar cooling bounds on new light particles: plasma mixing effects (2016, methodology): “[37, 38] also claim that there is a strong bound from the enhanced emission of SM neutrinos.”
• A facility to search for hidden particles at the CERN SPS: the SHiP physics case (2015, background): “If RH neutrinos are very light and also charged under B − L, this would impose very stringent constraints on mediators of B − L force [168].”
• Light dark matter: Models and constraints (2017, background): “We note that our estimates do not include plasma corrections, and refer to [134] for a treatment of these corrections in the context of a B − L boson with Dirac neutrinos.”
• The Dark Photon (2020, background): “- The B − L global symmetry (or other conserved flavor symmetries) are gauged and taken to be the U(1) group of the dark photon, which mixes with the hyper-charge (Bauer et al., 2018; Fayet, 2017; Heeck, 2014).”
• Evidence for a sublattice weak gravity conjecture (2016, background): “For instance, equivalence principle tests tell us that any massless B − L gauge boson must have a coupling eB−L < ∼ 10−24 [48, 49].”
• Particle physics models for the 17 MeV anomaly in beryllium nuclear decays (2016, background): “To avoid thermalization, one needs the X-charge of νR to be less than 10 −9 [108] or very low reheat temperatures in the window between 1 MeV and mX ≈ 17 MeV.”