Pier Paolo Giardino

Probing the Higgs self coupling via single Higgs production at the LHC

A bstractWe propose a method to determine the trilinear Higgs self coupling that is alternative to the direct measurement of Higgs pair production total cross sections and differential distributions. The method relies on the effects that electroweak loops featuring an anomalous trilinear coupling would imprint on single Higgs production at the LHC. We first calculate these contributions to all the phenomenologically relevant Higgs production (ggF, VBF, WH, ZH, tt¯H

Constraints on the trilinear Higgs self coupling from precision observables

t\overline{t}H

Higgs decays to

) and decay γγ,WW∗/ZZ∗→4f,bb¯,ττ

and

\left(\gamma \gamma, W{W}^{\ast }/Z{Z}^{\ast}\to\ 4f,b\overline{b},\tau \tau \right)

in the standard model effective field theory: An NLO analysis

modes at the LHC and then estimate the sensitivity to the trilinear coupling via a one-parameter fit to the single Higgs measurements at the LHC 8 TeV. We find that the bounds on the self coupling are already competitive with those from Higgs pair production and will be further improved in the current and next LHC runs.

Probing the top-quark width using the charge identification of b jets

We compute the next-to-leading order virtual QCD corrections to Higgs-pair production via gluon fusion. We present analytic results for the two-loop contributions to the spin-0 and spin-2 form factors in the amplitude. The reducible contributions, given by the double-triangle diagrams, are evaluated exactly while the two-loop irreducible diagrams are evaluated by an asymptotic expansion in heavy top-quark mass up to and including terms of