U(2) and Minimal Flavour Violation in Supersymmetry

Abstract

Rather than sticking to the full U (3) 3 approximate symmetry normally invoked in Minimal Flavour Violation, we analyze the consequences on the current flavour data of a suitably broken U (2) 3 symmetry acting on the first two generations of quarks and squarks. A definite correlation emerges between the ∆F = 2 amplitudes M(K 0 → K0 ), M(B d → Bd ) and M(B s → Bs ), which can resolve the current tension between between M(K 0 → K0 ) and M(B d → Bd ), while predicting M(B s → Bs ). In particular, the CP violating asymmetry in B s → ψφ is predicted to be positive S ψφ = 0.12 ± 0.05 and above its Standard Model value (S ψφ = 0.041 ± 0.002). The preferred region for the gluino and the left-handed sbottom masses is below about 1 ÷ 1.5 TeV. An existence proof of a dynamical model realizing the U (2) 3 picture is outlined.

B-decay CP-asymmetries in SUSY with a U(2)3 flavour symmetry

“…rare decays, studying in particular possible signatures of CP violation correlated with the predicted CP violation in meson mixing (∆F = 2). Contrary to the ∆F = 2 sector, where the pattern of deviations from the SM identified in [10] is unambiguously dictated by the U (2) 3 symmetry, the predictions of ∆F = 1 observables are more model dependent. In this analysis we concentrate on a framework with moderate values of tan β and, in order to establish a link between ∆F = 2 and ∆F = 1 CP-violating observables, we take small flavour-blind phases and assume the dominance of gluinomediated flavour-changing amplitudes.…”

“…While the lower bounds on first two generation squark masses from LHC are approaching a TeV, third generation squarks can still be in the few-hundred GeV region for gluino masses above about 600 GeV, depending on the gluino decay branching ratios and on the lightest neutralino mass. 1 Motivated by these facts, a U (2) 3 symmetry has been considered in [10] together with a hierarchical squark spectrum and has been shown to solve, in addition to the abovementioned problems, tensions present in the fits of the CKM matrix by contributing to CP violation in meson mixing. In this way, a non-standard B s mixing phase was predicted, as currently hinted by Tevatron data [11,12].…”

“…The purpose of this article is to extend the analysis in [10] to ∆F = 1 processes, i.e. rare decays, studying in particular possible signatures of CP violation correlated with the predicted CP violation in meson mixing (∆F = 2).…”

On the validity of the effective field theory for dark matter searches at the LHC, part II: complete analysis for the s-channel

“…1 A normalization proportional to the quark mass is common in many models motivated by flavour physics, but in general the coefficient Λ 3 at the denominator can have a different form. For example, if the effective operators come from a Naturalness-motivated new physics theory like Supersymmetry or Composite Higgs Models, assuming a U (2) 3 flavour symmetry [36,37] the normalization would be…”

Anomalies in $B$-decays and $U(2)$ flavour symmetry

“…in the notation of Ref. [9,10], and Φ is a leptoquark singlet under G F , carrying either one of the following quantum numbers under the SM gauge group:…”