SMEFT atlas of ∆F = 2 transitions

Abstract

We present a model-independent anatomy of the ∆F = 2 transitions K0−$$ {\overline{K}}^0 $$ K ¯ 0 , Bs,d−$$ {\overline{B}}_{s,d} $$ B ¯ s , d and D0−$$ {\overline{D}}^0 $$ D ¯ 0 in the context of the Standard Model Effective Field Theory (SMEFT). We present two master formulae for the mixing amplitude [M12]BSM. One in terms of the Wilson coefficients (WCs) of the Low-Energy Effective Theory (LEFT) operators evaluated at the electroweak scale μew and one in terms of the WCs of the SMEFT operators evaluated at the BSM scale Λ. The coefficients $$ {P}_a^{ij} $$ P a ij entering these formulae contain all the information below the scales μew and Λ, respectively. Renormalization group effects from the top-quark Yukawa coupling play the most important role. The collection of the individual contributions of the SMEFT operators to [M12]BSM can be considered as the SMEFT atlas of ∆F = 2 transitions and constitutes a travel guide to such transitions far beyond the scales explored by the LHC. We emphasize that this atlas depends on whether the down-basis or the up-basis for SMEFT operators is considered. We illustrate this technology with tree-level exchanges of heavy gauge bosons (Z′, G′) and corresponding heavy scalars.

Top, Higgs, diboson and electroweak fit to the Standard Model effective field theory

“…riety of studies of the SMEFT, for example, in electroweak processes [106][107][108][109][110][111], flavour physics [112][113][114][115][116][117][118][119][120], low-energy precision data [121][122][123], diboson measurements [124][125][126][127][128][129][130][131], at dimension 8 [87,88,[132][133][134][135][136] (where collider positivity constraints are particularly relevant [136][137][138][139][140]), and its connection with UV-complete models, both at tree-level [141][142][143][144][145][146][147] and one-loop [148][149][150]…”

The flavor of UV physics

“…To pin down the flavor structure of Wilson coefficients in the SMEFT, we rely on observations of flavor violation among SM particles. Flavor-changing rare meson decays or meson mixing are extremely sensitive to BSM effects [21][22][23][24][25][26][27][28] and measured with high precision. Although such observables tell us much about flavor in BSM physics, they often probe combinations of several Wilson coefficients.…”

“…This would allow us to probe all directions in WET that are relevant in b → s transitions JHEP05(2021)257 in MFV, see table 5. Another interesting addition would be B s meson mixing [28], which is sensitive to flavor structures with only third-generation quarks. Due to the strong correlation of the hadronic inputs for B s → µ + µ − and ∆m s , adding B s mixing require a combined analysis with B s → µ + µ − .…”

Exploiting dijet resonance searches for flavor physics

“…Taking the low-energy matrix elements from [74] and the constraints from UTFit [75], 8 we get the limit on y L 12 as a function of the diquark mass as shown as a red line in figure 9. This bound is reported as an upper limit on the product y L * 12 y R 13 as a function of m Φ 6 of figure 5 by setting y R 13 to either its maximal possible value from perturbativity or to be equal to y L 12 .…”