Zero-jettiness beam functions at N3^3LO

The zero-jettiness beam functions describe collinear emissions from initial state legs and appear in the factorisation theorem for cross sections in the limit of small zero-jettiness. They are an important building block for slicing schemes for colour-singlet production at hadron colliders. We report on our ongoing calculation of this quantity at next-to-next-to-next-to-leading order (N$^3$LO) in QCD, highlighting in particular the aspects of partial fraction relations and the calculation of master integrals.Comment: 12 pages, 2 figures, contribution to the proceedings of "Loops and Legs in Quantum Field Theory - LL2022, 25-30 April, 2022, Ettal, Germany

Higgs decay into massive b-quarks at NNLO QCD in the nested soft-collinear subtraction scheme

We present a fully differential description of a decay of a scalar Higgs boson into massive b-quarks valid at next-to-next-to-leading order (NNLO) in perturbative quan- tum chromodynamics (QCD). We work within the nested soft-collinear subtraction scheme extended to accommodate massive partons. We include the loop-induced contribution in- volving a Higgs coupling to a top quark. We test our calculation against results existing in the literature, comparing the predictions for the total decay width and jet rates

Beam functions for N-jettiness at N3^3LO in perturbative QCD

We present a calculation of all matching coefficients for N-jettiness beam functions at next-to-next-to-next-to-leading order (N$^3$LO) in perturbative quantum chromodynamics (QCD). Our computation is performed starting from the respective collinear splitting kernels, which we integrate using the axial gauge. We use reverse unitarity to map the relevant phase-space integrals to loop integrals, which allows us to employ multi-loop techniques including integration-by-parts identities and differential equations. We find a canonical basis and use an algorithm to establish non-trivial partial fraction relations among the resulting master integrals, which allows us to reduce their number substantially. By use of regularity conditions, we express all necessary boundary constants in terms of an independent set, which we compute by direct integration of the corresponding integrals in the soft limit. In this way, we provide an entirely independent calculation of the matching coefficients which were previously computed in ref. [1]

Beam functions for N-jettiness at N3^3LO in perturbative QCD

We present a calculation of all matching coefficients for N-jettiness beam functions at next-to-next-to-next-to-leading order (N$^3$LO) in perturbative quantum chromodynamics (QCD). Our computation is performed starting from the respective collinear splitting kernels, which we integrate using the axial gauge. We use reverse unitarity to map the relevant phase-space integrals to loop integrals, which allows us to employ multi-loop techniques including integration-by-parts identities and differential equations. We find a canonical basis and use an algorithm to establish non-trivial partial fraction relations among the resulting master integrals, which allows us to reduce their number substantially. By use of regularity conditions, we express all necessary boundary constants in terms of an independent set, which we compute by direct integration of the corresponding integrals in the soft limit. In this way, we provide an entirely independent calculation of the matching coefficients which were previously computed in arXiv:2006.03056

Quark beam function at next-to-next-to-next-to-leading order in perturbative QCD in the generalized large-approximation

We present the matching coefficient for the quark beam function at next-to-next-to-next-to-leading order in perturbative QCD in the generalized large Nc-approximation, Nc ∼ Nf ≫ 1. Although several refinements are still needed to make this result interesting for phenomenological applications, our computation shows that a fully-differential description of simple color singlet production processes at a hadron collider at N3LO in perturbative QCD is within reach

Bottom quark mass effects in associated WHWH production with H→bbˉH \to b\bar{b} decay through NNLO QCD

We present a computation of NNLO QCD corrections to the production of a Higgs boson in association with a $W$ boson at the LHC followed by the decay of the Higgs boson to a $b\bar{b}$ pair. At variance with previous NNLO QCD studies of the same process, we treat $b$ quarks as massive. An important advantage of working with massive $b$ quarks is that it makes the use of flavor jet algorithms unnecessary and allows us to employ conventional jet algorithms to define $b$ jets. We compare NNLO QCD descriptions of the associated $WH(b\bar{b})$ production with massive and massless $b$ quarks and also contrast them with the results provided by parton showers. We find ${\cal O}(5\%)$ differences in fiducial cross sections computed with massless and massive $b$ quarks. We also observe that much larger differences between massless and massive results, as well as between fixed-order and parton-shower results, can arise in selected kinematic distributions.Comment: 30 pages, 9 figure