Probing lepton-flavour universality with $$K\rightarrow \pi \nu \bar{\nu }$$ K → π ν ν ¯ decays
Abstract We analyse the rare processes $$K\rightarrow \pi \nu \bar{\nu }$$ K → π ν ν ¯ in view of the recent hints of violations of lepton-flavour universality (LFU) observed in B meson decays. If, as suggested by present data, the new interactions responsible for LFU violations couple mainly to the...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
SpringerOpen
2017-09-01
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| Series: | European Physical Journal C: Particles and Fields |
| Online Access: | http://link.springer.com/article/10.1140/epjc/s10052-017-5202-1 |
| Summary: | Abstract We analyse the rare processes $$K\rightarrow \pi \nu \bar{\nu }$$ K → π ν ν ¯ in view of the recent hints of violations of lepton-flavour universality (LFU) observed in B meson decays. If, as suggested by present data, the new interactions responsible for LFU violations couple mainly to the third generation of left-handed fermions, $$K\rightarrow \pi \nu \bar{\nu }$$ K → π ν ν ¯ decays turn out to be particularly interesting: these are the only kaon decays with third-generation leptons (the $$\tau $$ τ neutrinos) in the final state. In order to relate B-physics anomalies and K decays we adopt an effective field theory approach, assuming that the new interactions satisfy an approximate $$U(2)_q\times U(2)_\ell $$ U ( 2 ) q × U ( 2 ) ℓ flavour symmetry. In this framework we show that O(1) deviations from the Standard Model predictions in $$K\rightarrow \pi \nu \bar{\nu }$$ K → π ν ν ¯ branching ratios, closely correlated to similar effects in $$B\rightarrow K^{(*)}\nu \bar{\nu }$$ B → K ( ∗ ) ν ν ¯ , are naturally expected. The correlation of $$\mathcal {B}(K \rightarrow \pi \nu \bar{\nu })$$ B ( K → π ν ν ¯ ) , $$\mathcal {B}(B\rightarrow K^{(*)}\nu \bar{\nu })$$ B ( B → K ( ∗ ) ν ν ¯ ) , and the LFU violations in B decays would provide a very valuable tool to shed more light on this interesting phenomenon. |
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| ISSN: | 1434-6044 1434-6052 |