Monolepton production in SMEFT to $$ \mathcal{O} $$(1/Λ4) and beyond

Self Cite

In this paper we explore pp → W±(ℓ±ν)γ to $$ \mathcal{O}\left(1/{\Lambda}^4\right) $$ O 1 / Λ 4 in the SMEFT expansion. Calculations to this order are necessary to properly capture SMEFT contributions that grow with energy, as the interference between energy-enhanced SMEFT effects at $$ \mathcal{O}\left(1/{\Lambda}^2\right) $$ O 1 / Λ 2 and the Standard Model is suppressed. We find that there are several dimension eight operators that interfere with the Standard Model and lead to the same energy growth, ~ $$ \mathcal{O}\left({E}^4/{\Lambda}^4\right) $$ O E 4 / Λ 4 , as dimension six squared. While energy-enhanced SMEFT contributions are a main focus, our calculation includes the complete set of $$ \mathcal{O}\left(1/{\Lambda}^4\right) $$ O 1 / Λ 4 SMEFT effects consistent with U(3)5 flavor symmetry. Additionally, we include the decay of the W±→ ℓ±ν, making the calculation actually $$ \overline{q}{q}^{\prime}\to {\ell}^{\pm}\nu \gamma $$ q ¯ q ′ → ℓ ± νγ . As such, we are able to study the impact of non-resonant SMEFT operators, such as $$ \left({L}^{\dagger }{\overline{\sigma}}^{\mu }{\tau}^IL\right)\left({Q}^{\dagger }{\overline{\sigma}}^{\nu }{\tau}^IQ\right) $$ L † σ ¯ μ τ I L Q † σ ¯ ν τ I Q Bμν, which contribute to $$ \overline{q}{q}^{\prime}\to {\ell}^{\pm}\nu \gamma $$ q ¯ q ′ → ℓ ± νγ directly and not to $$ \overline{q}{q}^{\prime}\to {W}^{\pm}\gamma $$ q ¯ q ′ → W ± γ . We show several distributions to illustrate the shape differences of the different contributions.

“…For f f V vertices, the coupling deviations to O(1/Λ 4 ) can be found in ref. [29]. For the triboson coupling V V V , SMEFT effects will also introduce new kinematics.…”

Section: Smeft Contributions To Pp → W ± (ℓ ± )γmentioning

confidence: 99%

A case study of SMEFT $$ \mathcal{O}\left(1/{\Lambda}^4\right) $$ effects in diboson processes: pp → W±(ℓ±ν)γ

Martin

2024

Self Cite

“…The impact of these higher-order corrections in Drell-Yan has been recently discussed in refs. [44][45][46] for searches with light leptons without including detector effects. These works have shown that including the d = 8 contributions can have a significant impact when fitting SMEFT operators to Drell-Yan data at the LHC.…”

Section: Impact Of Dimension-8 Effectsmentioning

confidence: 99%

“…We explicitly checked this feature using the jack-knife and clipping procedures for specific examples [99,100]. Furthermore, following previous work in the literature [44,46], we estimated the relative contributions at O(1/Λ 4 ) between dimension-6 and (the often neglected) dimension-8 operators. In this case we explicitly showed that the precision of the measurements in the tails of the dilepton and monoleptons distributions (for all three lepton generations) are only sensitive to dimension-8 effects if: (i) the initial states are first generation valence quarks and (ii) the dimension-8 Wilson coefficients are uncorrelated from the dimension-6 ones.…”

Section: Jhep03(2023)064mentioning

confidence: 99%

“…This combination will be done for the Standard Model EFT (SMEFT) [42,43], with a consistent EFT expansion up to O(1/Λ 4 ) including d ≤ 8 contributions at the cross-section level (see refs. [44][45][46] for similar analyses), as well as for models with concrete mediators, which should be used if the experimental precision in a given channel is not sufficient to justify the EFT approach. In particular, implementing both EFT and concrete ultraviolet models will allow us to assess the range of EFT validity within a few selected examples.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Drell-Yan tails beyond the Standard Model

Allwicher

Faroughy

Jaffredo

et al. 2023

We investigate the high-pT tails of the pp → ℓν and pp → ℓℓ Drell-Yan processes as probes of New Physics in semileptonic interactions with an arbitrary flavor structure. For this purpose, we provide a general decomposition of the 2 → 2 scattering amplitudes in terms of form-factors that we match to specific scenarios, such as the Standard Model Effective Field Theory (SMEFT), including all relevant operators up to dimension-8, as well as ultraviolet scenarios giving rise to tree-level exchange of new bosonic mediators with masses at the TeV scale. By using the latest LHC run-II data in the monolepton (eν, μν, τν) and dilepton (ee, μμ, ττ, eμ, eτ, μτ) production channels, we derive constraints on the SMEFT Wilson coefficients for semileptonic four-fermion and dipole operators with the most general flavor structure, as well as on all possible leptoquark models. For the SMEFT, we discuss the range of validity of the EFT description, the relevance of $$ \mathcal{O} $$ O (1/Λ2) and $$ \mathcal{O} $$ O (1/Λ4) truncations, the impact of d = 8 operators and the effects of different quark-flavor alignments. Finally, as a highlight, we extract for several New Physics scenarios the combined limits from high-pT processes, electroweak pole measurements and low-energy flavor data for the b → cτν transition, showing the complementarity between these different observables. Our results are compiled in HighPT (https://highpt.github.io), a package in Mathematica which provides a simple way for users to extract the Drell-Yan tails likelihoods for semileptonic effective operators and for leptoquark models.

“…gauge and Higgs boson masses, gauge couplings, weak mixing angles [27], and even the fermionic mass and mixing angles of the Dirac Yukawa (flavor) sector of the (geo)SM(EFT) [32]. The geoSMEFT also gives rapid insight into the applicability/validity of schemes for estimating uncertainties coming from higher-order effects in fixed-order phenomenological SMEFT studies [33,34], has facilitated a global fit to electroweak precision data [35] and dedicated mono-lepton production study in the d = 8 SMEFT [36], and is also applicable to loop calculations as demonstrated in [37] for the SMEFT's Higgs tadpole.…”

Section: Jhep01(2023)069mentioning

confidence: 99%

The geometric νSMEFT: operators and connections

Talbert

2023

We write down a geometric realization of the Standard Model Effective Field Theory (SMEFT) extended by nf flavours of light sterile neutrinos, a so-called geoνSMEFT. As with the geoSMEFT introduced by Helset, Martin and Trott, we show that a refactorization of the νSMEFT’s operator product expansion is possible, such that two- and three-point composite operator forms are dressed with field-space connections composed of towers of Higgs dressings and symmetry generators, valid at all-orders in the $$ {\overline{v}}_T/\Lambda $$ v ¯ T / Λ expansion parameter of the EFT $$ \left({\overline{v}}_T\equiv \sqrt{2\left\langle {H}^{\dagger }H\right\rangle}\right) $$ v ¯ T ≡ 2 H † H . These connections are parameterized by real Higgs coordinates and contribute to the field-space geometry of the (ν)SMEFT, with structure linked to the strength of Beyond-the-(ν)Standard Model physics encoded in $$ {\overline{v}}_T/\Lambda $$ v ¯ T / Λ . In addition to enumerating the relevant composite operators and associated connections, we briefly outline the route to calculating all-$$ {\overline{v}}_T/\Lambda $$ v ¯ T / Λ -orders amplitudes, including the flavor-invariant theory required to understand the neutrino mass-eigenstate basis geometrically.