Higgs boson searches dominated the particle physics scenario for decades.This elusive particle has been deeply investigated in all its couplings with massive particles. Nowadays, some Higgs properties are known with high precision: mass, spin and parity. Despite that, many others are still largely unknown.

Two of the most important aspects under investigation are the Higgs decay and production widths and the behavior of its coupling as a function of the transverse momentum. The outcome of these studies might confirm the Standard Model prediction, or, if statistically significant discrepancies are found, constitute a bridge to new physics. New measurements of these quantities can be used to constrain the contribution of beyond Standard Model theories to the Higgs production, such as the one given by Effective Field Theories (EFTs) [1]. EFTs predict a large deviation from the Standard Model for the gluon-gluon fusion cross section manifesting at high pT. These effects can be probed by looking at Higgs boson produced with high transverse momentum decaying to b-quarks, which represents the dominant fraction of Higgs decays, fig 1.

The study of boosted Higgs bosons decaying to b-pairs in association with a jet is a powerful tool to investigate Beyond Standard Model in this context. The signature consists of two high pT jets, recoiling against each other, where one jet contains the bb system, very collimated because of the large Lorentz boost. The most important deliverable of this analysis is the differential measurement of the Higgs signal strength in pT bins. The results of the analysis using a dataset of 136 fb^-1 collected by the ATLAS detector were shown recently at the Moriond EW 2021 [2,3] conference. Fig.2 shows how the differential signal strength is consistent with Standard Model expectations within uncertainties even if a rising trend in pT is present.

Fig.1: An Higgs boson produced by a proton proton collision decays in a pair of highly collimated b-quarks.
Fig.2: A summary of the signal strengths measured in the various pT bins is shown.

[1] “Modeling BSM effects on the Higgs transverse- momentum spectrum in an EFT approach” M. Grazzini, A. Ilnicka, M. Spira, and M. Wiesemann, Journal of High Energy Physics, (115), 2017. URL: https: //doi.org/10.1007/JHEP03(2017)115.

[2] “Higgs Simplified Template and Differential Cross Section, David Shope on behalf of the ATLAS and CMS Collaborations” David Shope on behalf of the ATLAS Collaboration  http://moriond.in2p3.fr/2021/EW/slides/1_sm_08_David_Shope.pdf

[3] “Study of Higgs-boson production with large transverse momentum using the H→bb decay with the ATLAS detector” ATLAS Collaboration, ATLAS-CONF-2021-010 (2021)