Three recent OPAL studies are presented in which the fragmentation process in quark and gluon jets and in identified up, down and strange flavour jets is studied. The first is a measurement is of charged particle, π, η and K multiplicities in quark and gluon jets. No evidence is found for a particle species dependent multiplicity enhancement in gluon jets. In another study leading π, K, K S , p...

We summarize the physics case of a high-luminosity e+e− flavour factory collecting an integrated luminosity of 50 − 75 ab. Many New Physics sensitive measurements involving B and D mesons and τ leptons, unique to a Super Flavour Factory, can be performed with excellent sensitivity to new particles with masses up to ∼ 100 (or even ∼ 1000) TeV. Flavourand CP -violating couplings of new particles ...

We investigate the impact on low energy flavour mixing phenomena of the renormalisation group running of parameters in supersymmetric theories. We have explicitly chosen flavour dependent supergravity couplings. The renormalisation group equations are displayed in general matrix form. We work in a scale dependent basis such that the hierarchy in the quark masses can be more easily utilised. Sim...

We present a new geometric approach to the flavour decomposition of an arbitrary soft supersymmetry-breaking sector in the MSSM. Our approach is based on the geometry that results from the quark and lepton Yukawa couplings, and enables us to derive the necessary and sufficient conditions for a linearly-independent basis of matrices related to the completeness of the internal [SU(3) ⊗ U(1)] flav...

An exact numerical calculation of neutrino emissivity of two and three flavour quark matter have been carried out. We find that the neutrino emissivity obtained from the Iwamoto formula is in qualitative agreement with our calculation for two flavour quark matter. For three flavour case, on the other hand we find that the Iwamoto formula overestimates the numerical values by ∼2 orders of magnit...

Lepton-flavour symmetry in the Standard Model is broken by small masses for charged leptons and neutrinos. Introducing neutrino masses via dimension-5 operators associated to lepton-number violation at a very high scale, the corresponding coupling matrix may still have entries of order 1, resembling the situation in the quark sector with large top Yukawa coupling. As we have shown recently, in ...

We discuss the current and prospective limits that can be placed on supersymmetric contributions to b → s transitions in the Minimal Supersymmetric Standard Model with general flavour mixing amongst the squarks. We consider three processes: B̄ → Xsγ, B̄s → μ+μ− and B̄s − Bs mixing, and pay particular attention to the large tan β regime and beyond leading order contributions where the difference be...

— I review recent progress in theoretical calculations related to the CKM unitarity triangle. After briefly discussing hints for new physics in Bd−Bd and Bs−Bs mixing I present three topics of MSSM flavour physics: First I discuss new tanβ-enhanced radiative corrections to flavour-changing neutral current (FCNC) amplitudes which go beyond the familiar Higgs-mediated FCNC diagrams and may enhanc...

The misalignment of strong interactions with spontaneously broken electroweak interactions can produce mixing-angle-dependent mass hierarchies for asymptotic states. A framework of computation of the two types of parameters is presented. The origin of mass hierarchies still appears as an unsolved problem of today's particle physics, and equally puzzling is the one of mixing angles [1]. I uncove...

We study three flavour chiral perturbation theory in a limit where the strange quark mass is much larger than the external momenta and the up and down quark masses, and where the external fields are those of two–flavour chiral perturbation theory. In this case, the theory reduces to the one of SU(2)L × SU(2)R. Through this reduction, one can work out the strange quark mass dependence of the LEC...