The prescription for the γ5 matrix within dimensional regularization in multiloop calculations is elaborated. The three-loop anomalous dimension of the singlet axial current is calculated.

The renormalization of the axial anomaly in dimensional regularization

Collider physics at the precision frontier

We combine the NNLO QCD description of Higgs boson production in association with an electroweak vector boson $V = W~{\rm or}~Z$ with a similarly-precise description of Higgs boson decays into a pair of massive $b$ quarks and with the anomalous couplings that modify interactions of the Higgs and electroweak vector bosons. The resulting numerical code provides the most advanced theoretical tool to investigate such anomalous couplings in the associated Higgs boson production process. We study the impact of anomalous couplings on fiducial cross sections and differential distributions and argue that, with increased QCD precision, smaller anomalous couplings become accessible in kinematic regions where the effects of higher-dimensional operators in the Standard Model Effective Field Theory remain small and the EFT expansion is under control.

Anomalous couplings in associated $VH$ production with Higgs decay to massive $b$ quarks at NNLO in QCD

The bottom quark forward-backward asymmetry (${A}_{\mathrm{FB}}^{b}$) data at LEP exhibits a long-standing discrepancy with the standard model prediction. We propose a novel method to probe the $Zb\overline{b}$ interactions through $gg\ensuremath{\rightarrow}Zh$ production at the LHC, which is sensitive to the axial-vector component of the $Zb\overline{b}$ couplings. The apparent degeneracy of the anomalous $Zb\overline{b}$ couplings implied by the LEP precision electroweak measurements seems to be resolved by the current 13 TeV LHC $Zh$ data, which is, however, dominated by the two data points with high transverse momentum of $Z$ boson whose central values are in conflict with the standard model prediction. We also show the potential of the HL-LHC to either verify or exclude the anomalous $Zb\overline{b}$ couplings observed at LEP through measuring the $Zh$ production rate at the HL-LHC, and this conclusion is not sensitive to the possible new physics contribution induced by top quark or Higgs boson anomalous couplings in the loop.

Anomalous Zbb[over ¯] Couplings: From LEP to LHC.

Higgs boson self-coupling constraints from single Higgs, double Higgs and Electroweak measurements

We compute the next-to-leading virtual QCD corrections to the partonic cross section of the production of a Higgs boson in association with a $Z$ boson in gluon fusion. The calculation is based on the recently introduced method of evaluating the amplitude via an expansion in terms of a small transverse momentum. We generalize the method to the case of different masses in the final state and of a process not symmetric in the forward-backward direction exchange. Our analytic approach gives a very good approximation (better than percent) of the partonic cross section in the center of mass energy region up to $\sim 750 \,\textrm{GeV}$, where at the LHC $\sim 98\%$ of the total hadronic cross section is concentrated.

/pdf/virtual-corrections-to-gg-zh-via-a-transverse-momentum-dxjt9p7tad.pdf

Virtual corrections to gg → ZH via a transverse momentum expansion

Gluon fusion production at NLO: merging the transverse momentum and the high-energy expansions

A bstract The virtual corrections to gg → HH and gg → ZH are analytically evaluated combining an expansion in the small transverse momentum of the final particles with an expansion valid at high energies. The two expansion methods describe complementary regions of the phase space and we merge their results, extending the range of validity of both expansions using Padé approximants. We show that this approach can reproduce the available numerical results retaining the exact top quark mass dependence with an accuracy below the 1% level. Our results allow a fast and flexible evaluation of the virtual corrections of the considered processes. Furthermore, they are available in different renormalisation schemes of the top quark mass. 

/pdf/gluon-fusion-production-at-nlo-merging-the-transverse-3pkhqwf7.pdf

We compute the two-loop effects induced by an anomalous Higgs trilinear self-coupling in the partial decay width h to gamma Z. The computation is performed using the anomalous coupling approach working in the unitary gauge and in a theory in which the anomalous coupling is generated via the addition to the scalar potential part of the Standard Model Lagrangian of an (in)finite tower of (Phi^dagger Phi)^n terms. The former computation is automatically finite while the latter requires the renormalization of the lowest order contribution. We discuss the renormalization conditions that should be employed in order to obtain the same result in the two approaches. We find that the h to gamma Z process is one of the most sensitive mode to an anomalous trilinear Higgs self-coupling. As a by-product of this work we confirm one of two different results present in the literature concerning the contribution of an anomalous Higgs trilinear coupling in the h to gamma gamma decay.

/pdf/the-effect-of-an-anomalous-higgs-trilinear-self-coupling-on-2xluhihqkv.pdf

The effect of an anomalous Higgs trilinear self-coupling on the h to gamma Z decay

https://link.springer.com/content/pdf/10.1007/JHEP08(2022)009.pdf

Marco Vitti

Papers

Virtual corrections to gg → ZH via a transverse momentum expansion

Gluon fusion production at NLO: merging the transverse momentum and the high-energy expansions

Gluon fusion production at NLO: merging the transverse momentum and the high-energy expansions

The effect of an anomalous Higgs trilinear self-coupling on the h to gamma Z decay

On the NLO QCD corrections to gluon-initiated ZH production