Model-independent analysis of $$\varvec{b \rightarrow d}$$ processes

Abstract

AbstractWe perform a model-independent analysis of $$|\Delta b|=|\Delta d|=1$$ | Δ b | = | Δ d | = 1 processes to test the standard model and probe flavor patterns of new physics. Constraints on Wilson coefficients are obtained from global fits to $$B^+ \rightarrow \pi ^+ \,\mu ^+\mu ^-$$ B + → π + μ + μ - , $$B^0_s\rightarrow \bar{K}^{*0}\, \mu ^+\mu ^-$$ B s 0 → K ¯ ∗ 0 μ + μ - , $$B^0\rightarrow \mu ^+\mu ^-$$ B 0 → μ + μ - , and radiative $$B \rightarrow X_d \,\gamma $$ B → X d γ decays data. The fits are consistent with the standard model but leave sizable room for new physics. Besides higher-statistics measurements and more data in theory-friendly bins of the dilepton mass, further complementary observables such as angular distributions of $$B_s^0 \rightarrow \bar{K}^{*0}\,\ell ^+ \ell ^-$$ B s 0 → K ¯ ∗ 0 ℓ + ℓ - , $$B \rightarrow \rho \,\ell ^+ \ell ^-$$ B → ρ ℓ + ℓ - or the baryonic modes $$\Xi _b \rightarrow \Sigma \,\ell ^+ \ell ^-$$ Ξ b → Σ ℓ + ℓ - , $$\Omega _b^- \rightarrow \Xi ^- \, \ell ^+ \ell ^-$$ Ω b - → Ξ - ℓ + ℓ - are necessary to resolve the significant degeneracy in the fit for the semileptonic four-fermion operators. Assuming minimal quark flavor violation, the $$b \rightarrow s$$ b → s global fit implies tight constraints on the $$b \rightarrow d$$ b → d couplings, and hence allows to test this paradigm with improved data. Another benefit from $$|\Delta b|=|\Delta d|=1$$ | Δ b | = | Δ d | = 1 processes is to shed light on the B-anomalies in $$|\Delta b|=|\Delta s|=1$$ | Δ b | = | Δ s | = 1 modes from a new angle. Specifically, studies of lepton flavor-specific and dineutrino modes are informative on the lepton flavor structure. Rare $$b \rightarrow d \, \ell \ell , \nu \bar{\nu }$$ b → d ℓ ℓ , ν ν ¯ decays can be studied at high luminosity flavor facilities LHCb, Belle II, and a future Z-factory.