Constraining top-quark couplings combining top-quark and $$\varvec{B}$$ decay observables

Abstract

We present a first, consistent combination of measurements from top-quark and B physics to constrain topquark properties within the Standard Model Effective Field Theory (SMEFT). We demonstrate the feasibility and benefits of this approach and detail the ingredients required for a proper combination of observables from different energy scales. Specifically, we employ measurements of the ttγ cross section together with measurements of theB → X s γ branching fraction to test the Standard Model and look for new physics contributions to the couplings of the top quark to the gauge bosons within SMEFT. We perform fits of three Wilson coefficients of dimension-six operators considering only the individual observables as well as their combination to demonstrate how the complementarity between top-quark and B physics observables allows to resolve ambiguities and significantly improves the constraints on the Wilson coefficients. No significant deviation from the Standard Model is found with present data.

O new physics, where art thou? A global search in the top sector

“…Its biggest success has been the application to Higgs and electroweak boson measurements at the LHC [8][9][10][11][12][13]. Most recently, the same approach [14][15][16] has been used to systematically analyze top quark measurements at the LHC [17][18][19][20][21] and at future colliders [22,23] and their link to bottom sector [24]. These efforts pave the way towards a global SMEFT analysis at the LHC.…”

Constraining new physics with single top production at LHC

“…The processes that have been considered include top pair production [6][7][8][9][10], top decay [11,12], and top production in association with a Higgs [13,14] a Z or γ [8,14,15], or b quarks [16]. There have also been studies using low energy observables [17][18][19][20][21] as well as future lepton colliders [22][23][24][25][26][27][28]. In addition, there are several groups, TopFitter [29][30][31], SMEFiT [32], and SFitter [33] that have performed global fits to data to constrain the space of EFT operators coupling to tops.…”

New Physics Searches with Top Quarks

“…modifies the tbW coupling. It contributes to electroweak single-top production at the LHC, but also to rare semi-leptonic B meson decays B → K ( * ) + − : Several analyses have investigated this relation for a subset of operators and/or observables [11,15,16]. They find that flavor observables are generally more sensitive to top couplings than LHC observables.…”