and epsilon '/ epsilon in simplified new physics models

• Published in: The journal of high energy physics Vol. 2015; no. 11; pp. 1 - 33
• Main Authors: Buras, Andrzej J, Buttazzo, Dario, Knegjens, Robert
• Format: Journal Article
• Language: English
• Published: 01.11.2015
• Subjects: CERN; Correlation; Couplings; Decay; Mesons; Quantum chromodynamics; Standard model (particle physics); Texts
• ISSN: 1029-8479
• DOI: 10.1007/JHEP11(2015)166

(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).The decays ... and ..., being the theoretically cleanest rare decays of mesons, are very sensitive probes of New Physics (NP). In view of the excellent prospects of reaching the Standard Model (SM) sensitivity for ... by the NA62 experiment at CERN and for ... by the KOTO experiment at J-PARC, we study them in the simplest extensions of the SM in which stringent correlations between these two decays and other flavour observables are present. We first consider simple models with tree-level Z and Z' contributions in which either Minimal Flavour Violation (MFV) or a U(2) super(3) symmetry is imposed on the quark flavour-violating couplings. We then compare the resulting correlations with those present in generic models in which the latter couplings are arbitrary, subject to the constraints from Delta F = 2 processes, electroweak and collider data. Of particular interest are the correlations with epsilon '/ epsilon and K sub( )L arrow right mu super(+) mu super(-) which limit the size of NP contributions to ... and ..., depending on the Dirac structure of couplings and the relevant operators. But in MFV models also the constraint from B sub( )s arrow right mu super(+) mu super(-) turns out to be important. We take into account the recent results from lattice QCD and large N approach that indicate epsilon '/ epsilon in the SM to be significantly below the data. While in many models the enhancement of epsilon '/ epsilon implies the suppression of ..., we present two models in which epsilon '/ epsilon and ... can be simultaneously enhanced relative to SM predictions. A correlation between ... and B arrow right K(K super(*)) mu super(+) mu super(-), found by us in the simple models considered here, should be of interest for NA62 and LHCb experimentalists at CERN in the coming years. The one with ... will be tested at Belle II.