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331 Models Facing the Tensions in $Delta F=2$ Processes with the Impact on $varepsilon^prime/varepsilon$, $B_stomu^+mu^-$ and $Bto K^*mu^+mu^-$

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 نشر من قبل Fulvia De Fazio
 تاريخ النشر 2016
  مجال البحث
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Motivated by the recently improved lattice QCD results on the hadronic matrix elements entering $Delta M_{s,d}$ in $B_{s,d}^0-bar B_{s,d}^0$ mixings and the resulting increased tensions between $Delta M_{s,d}$ and $varepsilon_K$ in the Standard Model and CMFV models, we demonstrate that these tensions can be removed in 331 models based on the gauge group $SU(3)_Ctimes SU(3)_Ltimes U(1)_X$ both for $M_{Z^prime}$ in the LHC reach and well beyond it. But the implied new physics (NP) patterns in $Delta F=1$ observables depend sensitively on the value of $|V_{cb}|$. Concentrating the analysis on three 331 models that have been selected by us previously on the basis of their performance in electroweak precision tests and $varepsilon^prime/varepsilon$ we illustrate this for $|V_{cb}|=0.042$ and $|V_{cb}|=0.040$. We find that these new lattice data still allow for positive shifts in $varepsilon^prime/varepsilon$ up to $6times 10^{-4}$ for $M_{Z^prime}=3~TeV$ for both values of $$|V_{cb}|$ but for $M_{Z^prime}=10~TeV$ only for $|V_{cb}|=0.040$ such shifts can be obtained. NP effects in $B_stomu^+mu^-$ and in the Wilson coefficient $C_9$ are significantly larger in all three models for the case of $|V_{cb}|=0.040$. In particular in two models the rate for $B_stomu^+mu^-$ can be reduced by NP by $20%$ for $M_{Z^prime}=3~TeV$ resulting in values in the ballpark of central values from CMS and LHCb. In the third model a shift in $C_9$ up to $C_9^text{NP}=-0.5$ is possible. We also consider the simplest 331 model, analyzed recently in the literature, in which $X=Y$, the usual hypercharge. We find that in this model NP effects in flavour observables are much smaller than in the three models with $X ot=Y$, in particular NP contributions to the ratio $varepsilon^prime/varepsilon$ are very strongly suppressed.



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