Disentangling left and right-handed neutrino effects in $$B\rightarrow K^{(*)}\nu \nu $$
S. Rosauro-Alcaraz, Luighi P. S. Leal
Abstract
Abstract The first observation of $$\mathcal {B}\left( B^+\rightarrow K^+\nu \nu \right) $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>B</mml:mi> <mml:mfenced> <mml:msup> <mml:mi>B</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:mo>→</mml:mo> <mml:msup> <mml:mi>K</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:mi>ν</mml:mi> <mml:mi>ν</mml:mi> </mml:mfenced> </mml:mrow> </mml:math> by the Belle II experiment lies almost $$3\sigma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>3</mml:mn> <mml:mi>σ</mml:mi> </mml:mrow> </mml:math> away from the Standard Model expectation. In this letter we study this result in the SMEFT, extended by a light right-handed neutrino. We explore the correlations between the measured decay rate and other observables, such as $$\mathcal {B}\left( B\rightarrow K^*\nu \nu \right) $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>B</mml:mi> <mml:mfenced> <mml:mi>B</mml:mi> <mml:mo>→</mml:mo> <mml:msup> <mml:mi>K</mml:mi> <mml:mo>∗</mml:mo> </mml:msup> <mml:mi>ν</mml:mi> <mml:mi>ν</mml:mi> </mml:mfenced> </mml:mrow> </mml:math> and $$F_L\left( B\rightarrow K^*\nu \nu \right) $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>F</mml:mi> <mml:mi>L</mml:mi> </mml:msub> <mml:mfenced> <mml:mi>B</mml:mi> <mml:mo>→</mml:mo> <mml:msup> <mml:mi>K</mml:mi> <mml:mo>∗</mml:mo> </mml:msup> <mml:mi>ν</mml:mi> <mml:mi>ν</mml:mi> </mml:mfenced> </mml:mrow> </mml:math> , showing that they could disentangle among scenarios involving left-handed neutrinos and those with the right-handed ones. Furthermore, we find that the high- $$p_T$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>p</mml:mi> <mml:mi>T</mml:mi> </mml:msub> </mml:math> tails of Drell–Yan processes studied at LHC provide important constraints that help us exclude some of the scenarios consistent with the Belle II result.