Precision physics withBs0→J/ψϕat the LHC: The quest for new physics

Abstract

CP-violating effects in the time-dependent angular distribution of thedecay products play a key rôle for the search of new physics. The hadronic Standard-Model uncertainties are related to doubly Cabibbo-suppressed penguin contributions and are usually assumed to be negligibly small. In view of recent results from the Tevatron and the quickly approaching start of the data taking at the LHC, we have a critical look at the impact of these terms, which could be enhanced through long-distance QCD phenomena, and explore the associated uncertainty for the measurement of the CPviolating B 0 s -B 0 s mixing phase. We point out that these effects can actually be controlled by means of an analysis of the time-dependent angular distribution of the B 0decay products, and illustrate this through numerical studies. Moreover, we discuss SU (3)-breaking effects, which limit the theoretical accuracy of our method, and suggest internal consistency checks of SU (3).

A roadmap to control penguin effects in B d 0 → J/ψK S 0 and B s 0 → J/ψϕ

“…Concerning the B 0 s → J/ψφ channel, an analysis of CP violation is more involved as the final state consists of two vector mesons and thus is a mixture of different CP eigenstates which have to be disentangled through an angular analysis of their decay products [18,19]. In this case, the decays B 0 d → J/ψρ 0 [10] and B 0 s → J/ψK * 0 [15] are tools to take the penguin effects into account. The LHCb collaboration has very recently presented the first polarisation-dependent measurements of φ s from B 0 s → J/ψφ in ref.…”

“…neglecting ω-φ mixing (for a detailed discussion, see ref. [15]), this transition arises if we replace the down spectator quark of B 0 d → J/ψK 0 S by a strange quark. In analogy to eq.…”

“…the pion and kaon charges of K * 0 → π + K − and K * 0 → π − K + distinguish between initially present B 0 s and B 0 s mesons, respectively. Consequently, in order to determine the penguin parameters, we have to rely on direct CP violation and decay rate information [15]. For each of the finalstate configurations f ∈ {0, , ⊥}, we have a direct CP asymmetry A dir,f CP and an observable corresponding to eq.…”

“…[10]. The linear polarisation states are also employed for the theoretical description of the B 0 s → J/ψK * 0 decay, which has a flavour-specific final state [15].…”

“…The corresponding non-perturbative hadronic parameters cannot be calculated in a reliable way within QCD. However, in the era of high-precision measurements, these effects have to be controlled with the final goal to match the experimental and theoretical precisions [9][10][11][12][13][14][15][16][17].…”