Effects of universal extra dimensions on B0–B0 mixing

Abstract

We study contributions coming to ∆m B from one or more universal extra dimensions (UED) in which all the Standard Model fields can propagate. In the model with a single UED, the box diagrams for mixing are convergent and therefore insensitive to the cutoff scale of the theory. In the case of two UEDs, the result is not very sensitive to the cut-off scale due to GIM mechanism. Within the present range of the parameters at 1σ level, the lower bound on the compactification scale 1/R has been estimated to be 165 GeV for one UED and 280 GeV for two UEDs. The bound increases drastically if one can have a better determination of the B meson decay constant f B and the QCD correction parameter B B . For example, it rises to 740 GeV (for one UED) if the error (at 1σ) in the determination of f B √ B B from quenched latticecalculation is reduced to one-third from its present value. The UED contributions to the K system are strongly suppressed.

Search for Higgs bosons of the universal extra dimensions at the large Hadron collider

“…The presence of KK-towers for charged and neutral CP-odd Higgs bosons provides a concrete example of this. The phenomenology of KK-excitations has been studied in great detail in recent times which covers its implications at colliders [3,4,5,6,7,8,9,10,11,12,13,14,15,16], in electroweak/flavour sector via various low-energy observables [17,18,19,20,21,22,23,24,25,26,27,28] and for dark matter/cosmology [5,13,29,30,31,32,33,34,35,36,37,38,39,40] In MUED there are only two extra free parameters when compared to the SM. These are the radius of compactification R (or, alternately R −1 , the scale of compactification) and the cutoff scale Λ of the theory.…”

Flavor violation and extra dimensions

“…A lower bound on the compactification scale 1/R > ∼ 165 GeV has been obtained by requiring the KK contribution does not exceed the experimental central value ∆M B d < 0.484 (ps) −1 [18]. It is worth mentioning that with the above expression of H ∆B=2 eff , the phase θ KK defined in the previous section is identically zero, hence there is no new source of CP violation in this class of models and the CP asymmetry of B d → J/ψK S would be given by the SM value, sin 2β, which is consistent with the experimental measurements.…”

The e and decays in the general two Higgs Doublet model with the inclusion of one universal extra dimension

“…This size has been studied using the present experimental data in several works [9,10] and estimated as large as few hundereds of GeV [7,8,11], not to contradict with the experiments. Furthermore, the loop effects induced by the internal top quark are sensitive to the KK mode contributions and the size of the extra dimensions has been estimated in the range 200 − 500 GeV , using electroweak precision measurements [12], the B −B -mixing [13], [14] and the flavor changing process b → sγ [15].…”