Higgs decays to four leptons to $$ \mathcal{O}\left(1/{\Lambda}^4\right) $$ in SMEFT

A

bstract

We study the decays

and

$$ h\to \ell {\overline{\nu}}_{\ell }{\nu}_{\ell^{\prime }}{\overline{\ell}}^{\prime } $$ h → ℓ ν ¯ ℓ ν ℓ ′ ℓ ¯ ′

within the SMEFT framework and including effects up to

$$ \mathcal{O}\left(1/{\Lambda}^4\right) $$ O 1 / Λ 4

, where Λ is the new physics scale suppressing higher dimensional operators. To work to this order, we must include the square of dimension-six operators and the interference of dimension-eight operators with the Standard Model. We study angular asymmetries and other differential decay observables and determine which are most sensitive to

$$ \mathcal{O}\left(1/{\Lambda}^4\right) $$ O 1 / Λ 4

effects. While new kinematic structures arising in higher dimensional operators have the potential to induce novel angular dependency, we find this does not occur for

$$ h\to \ell \overline{\ell}\left(Z\to {\ell}^{\prime }{\overline{\ell}}^{\prime}\right) $$ h → ℓ ℓ ¯ Z → ℓ ′ ℓ ¯ ′

. For

$$ h\to \ell {\overline{\nu}}_{\ell }{\nu}_{\ell^{\prime }}{\overline{\ell}}^{\prime } $$ h → ℓ ν ¯ ℓ ν ℓ ′ ℓ ¯ ′

, new angular dependencies do arise at

$$ \mathcal{O}\left(1/{\Lambda}^4\right) $$ O 1 / Λ 4

, though they require a fully reconstructible (meaning we can go to the Higgs rest frame) final state. For non-reconstructible final states such as

$$ \ell {\overline{\nu}}_{\ell }{\nu}_{\ell^{\prime }}{\overline{\ell}}^{\prime } $$ ℓ ν ¯ ℓ ν ℓ ′ ℓ ¯ ′

, we must study Higgs production and decay together with the appropriate observables, which we find obscures the new angular effects.