1,313 research outputs found
Colleen : An Irish Love Song
https://digitalcommons.library.umaine.edu/mmb-vp/3482/thumbnail.jp
Patterns of Flavour Violation in a Warped Extra Dimensional Model with Custodial Protection
We present a particular warped extra dimensional model, where the flavour
diagonal and flavour non-diagonal Z boson couplings to left-handed down quarks
are protected by the custodial symmetry P_LR. After a brief introduction of the
model and of its main theoretical motivations, we present a complete study of
rare K and B meson decays, including K+ --> pi+ nu anti-nu, K_L --> pi0 nu
anti-nu, B_{s,d} --> mu+ mu- and B_{s,d} --> X_{s,d} nu anti-nu. In particular
we restrict the parameter space of the model to the subspace which fits all
quark masses, CKM mixing parameters and all the measured Delta F=2 observables,
keeping the Kaluza-Klein scale in the reach of LHC (~(2-3)TeV). There we show
that, in addition to the one loop contribution of the Standard Model (SM), the
dominating new physics contribution to the rare decays of K and B_{s,d} mesons
is the tree level exchange of the Z boson of the SM governed by right-handed
couplings to down-type quarks. In order to reduce the parameter dependence, we
study correlations between various branching ratios of B and K mesons and
between Delta F=1 and Delta F=2 observables. The patterns that we find allow to
distinguish this new physics scenario from the SM and can offer an opportunity
to future experiments to confirm or rule out the model.Comment: 10 pages, 8 figures, To appear in the proceedings of DISCRETE '08,
11-16 December 2008, Valencia, Spai
Electroweak and Flavour Structure of a Warped Extra Dimension with Custodial Protection
We present the electroweak and flavour structure of a model with a warped
extra dimension and the bulk gauge group SU(3) x SU(2)_L x SU(2)_R x P_LR x
U(1)_X. The presence of SU(2)_R implies an unbroken custodial symmetry in the
Higgs system allowing to eliminate large contributions to the T parameter,
whereas the P_LR symmetry and the enlarged fermion representations provide a
custodial symmetry for flavour diagonal and flavour changing couplings of the
SM Z boson to left-handed down-type quarks. We diagonalise analytically the
mass matrices of charged and neutral gauge bosons including the first KK modes.
We present the mass matrices for quarks including heavy KK modes and discuss
the neutral and charged currents involving light and heavy fields. We give the
corresponding complete set of Feynman rules in the unitary gauge.Comment: 74 pages, 2 figures. clarifying comments and references added,
version to be published in JHE
Lepton flavour violation in The Little Higgs model
Little Higgs models with T-parity have a new source of lepton flavour
violation. In this paper we consider the anomalous magnetic moment of the muon
\gmtwo and the lepton flavour violating decays \mutoeg and \tautomug in Little
Higgs model with T-parity \cite{Goyal:2006vq}. Our results shows that present
experimental constraints of \mutoeg is much more useful to constrain the new
sources of flavour violation which are present in T-parity models.Comment: LaTeX file with 13 eps figures (included
The Impact of a 4th Generation on Mixing and CP Violation in the Charm System
We study D0-D0 mixing in the presence of a fourth generation of quarks. In
particular, we calculate the size of the allowed CP violation which is found at
the observable level well beyond anything possible with CKM dynamics. We
calculate the semileptonic asymmetry a_SL and the mixing induced CP asymmetry
eta_fS_f which are correlated with each other. We also investigate the
correlation of eta_fS_f with a number of prominent observables in other mesonic
systems like epsilon'/epsilon, Br(K_L -> pi0 nu nu), Br(K+ -> pi+ nu nu),
Br(B_s ->mu+ mu-), Br(B_d -> mu+ mu-) and finally S_psi phi in the B_s system.
We identify a clear pattern of flavour and CP violation predicted by the SM4
model: While simultaneous large 4G effects in the K and D systems are possible,
accompanying large NP effects in the B_d system are disfavoured. However this
behaviour is not as pronounced as found for the LHT and RSc models. In contrast
to this, sizeable CP violating effects in the B_s system are possible unless
extreme effects in eta_fS_f are found, and Br(B_s ->mu+ mu-) can be strongly
enhanced regardless of the situation in the D system. We find that, on the
other hand, S_psi phi > 0.2 combined with the measured epsilon'/epsilon
significantly diminishes 4G effects within the D system.Comment: 22 pages, 23 figures, v2 (references added
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