B meson

Quantum mechanics

Quark

Algorithm

Electroweak scale

Lepton

Nuclear physics

Particle physics

Effective field theory

Computer science

Leptoquark

Physics

Renormalization group

Electron

Physics beyond the Standard Model

Electroweak interaction

The European Physical Journal C

Following the updated measurement of the lepton flavour universality (LFU) ratio $$R_K$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>R</mml:mi><mml:mi>K</mml:mi></mml:msub></mml:math> in $$B\rightarrow K\ell \ell $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>B</mml:mi><mml:mo>→</mml:mo><mml:mi>K</mml:mi><mml:mi>ℓ</mml:mi><mml:mi>ℓ</mml:mi></mml:mrow></mml:math> decays by LHCb, as well as a number of further measurements, e.g. $$R_{K^*}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>R</mml:mi><mml:msup><mml:mi>K</mml:mi><mml:mo>∗</mml:mo></mml:msup></mml:msub></mml:math> by Belle and $$B_s \rightarrow \mu \mu $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>B</mml:mi><mml:mi>s</mml:mi></mml:msub><mml:mo>→</mml:mo><mml:mi>μ</mml:mi><mml:mi>μ</mml:mi></mml:mrow></mml:math> by ATLAS, we analyse the global status of new physics in $$b\rightarrow s$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>b</mml:mi><mml:mo>→</mml:mo><mml:mi>s</mml:mi></mml:mrow></mml:math> transitions in the weak effective theory at the b -quark scale, in the Standard Model effective theory above the electroweak scale, and in simplified models of new physics. We find that the data continues to strongly prefer a solution with new physics in semi-leptonic Wilson coefficients. A purely muonic contribution to the combination $$C_9 = -C_{10}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>C</mml:mi><mml:mn>9</mml:mn></mml:msub><mml:mo>=</mml:mo><mml:mo>-</mml:mo><mml:msub><mml:mi>C</mml:mi><mml:mn>10</mml:mn></mml:msub></mml:mrow></mml:math> , well suited to UV-complete interpretations, is now favoured with respect to a muonic contribution to $$C_9$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>C</mml:mi><mml:mn>9</mml:mn></mml:msub></mml:math> only. An even better fit is obtained by allowing an additional LFU shift in $$C_9$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>C</mml:mi><mml:mn>9</mml:mn></mml:msub></mml:math> . Such a shift can be renormalization-group induced from four-fermion operators above the electroweak scale, in particular from semi-tauonic operators, able to account for the potential discrepancies in $$b \rightarrow c$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>b</mml:mi><mml:mo>→</mml:mo><mml:mi>c</mml:mi></mml:mrow></mml:math> transitions. This scenario is naturally realized in the simplified $$U_1$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>U</mml:mi><mml:mn>1</mml:mn></mml:msub></mml:math> leptoquark model. We also analyse simplified models where a LFU effect in $$b\rightarrow s\ell \ell $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>b</mml:mi><mml:mo>→</mml:mo><mml:mi>s</mml:mi><mml:mi>ℓ</mml:mi><mml:mi>ℓ</mml:mi></mml:mrow></mml:math> is induced radiatively from four-quark operators and show that such a setup is on the brink of exclusion by LHC di-jet resonance searches.

B-decay discrepancies after Moriond 2019