Consistent searches for SMEFT effects in non-resonant dijet events

Abstract

We investigate the bounds which can be placed on generic new-physics contributions to dijet production at the LHC using the framework of the Standard Model Effective Field Theory, deriving the first consistently-treated EFT bounds from non-resonant high-energy data. We recast an analysis searching for quark compositeness, equivalent to treating the SM with one higher-dimensional operator as a complete UV model. In order to reach consistent, model-independent EFT conclusions, it is necessary to truncate the EFT effects consistently at order 1/Λ 2 and to include the possibility of multiple operators simultaneously contributing to the observables, neither of which has been done in previous searches of this nature. Furthermore, it is important to give consistent error estimates for the theoretical predictions of the signal model, particularly in the region of phase space where the probed energy is approaching the cutoff scale of the EFT. There are two linear combinations of operators which contribute to dijet production in the SMEFT with distinct angular behavior; we identify those linear combinations and determine the ability of LHC searches to constrain them simultaneously. Consistently treating the EFT generically leads to weakened bounds on new-physics parameters. These constraints will be a useful input to future global analyses in the SMEFT framework, and the techniques used here to consistently search for EFT effects are directly applicable to other off-resonance signals.

Matching for FCNC effects in the flavour-symmetric SMEFT

“…Loop corrections to very precisely measured and particularly interesting processes have been calculated [20][21][22][23][24][25][26][27][28][29][30][31][32]. LHC searches have also been interpreted in the SMEFT, with techniques to address the unique theoretical errors inherent in high energy searches for EFT effects recently developed [33,34]. Ultimately, all of these contributions will need to coalesce into a fully global fit of the SMEFT Wilson coefficients and cutoff scale, as only then will it be possible to truly understand the conservative constraints which can be imposed on an arbitrary model through matching to the SMEFT and comparison of a given parameter point to the likelihood associated with all the relevant measurements.…”

Constraining the SMEFT with Bayesian reweighting

“…For instance, without flavour assumptions, one needs to deal with N op = 2499 independent operators corresponding to three fermion generations. Because of this challenge, the complexity and breadth of SMEFT analyses, in particular of LHC data, has been restricted to a subset of higher-dimensional operators so far, typically clustered in sectors that are assumed to be independent from each other [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22].…”

Dijets at Tevatron cannot constrain SMEFT four-quark operators

“…A consistent and conservative technique to derive bounds on the SMEFT from collider searches has been developed in [32] and further applied in [33]; it utilizes the well-understood techniques of perturbation theory in the context of the expansion in inverse powers of the new physics scale Λ. There are two important steps which, prior to the introduction of this technique, have not been consistently performed in searching for higher-dimension effects in the SMEFT or any other EFT-based framework for model-independent new physics parameterization in collider searches.…”

“…In this article we utilize the prescription of [32], and follow up on the insight of [33] that lower-energy colliders can provide constraints complementary to those which can be extracted from the LHC. We thus explore the application of Tevatron data in the dijet channel to the SMEFT.…”