The thrust distribution at NNLO+NNLL in Higgs decays to quarks and gluons

A bstract We present a calculation of the thrust distribution in Higgs decays to quarks and gluons, H→ bb̄ H → b b ¯ , H→ cc̄ H → c c ¯ , and H → gg , including the resummation of large logarithmic corrections that arise in the two-particle limit at next-to-next-to-leading logarithmic (NNLL) accuracy, and match it to fixed-order results for three-particle decays at next-to-next-to-leading order (NNLO) in the strong coupling. The resummation is performed analytically within the A res framework and combined with the fixed-order results using the logR matching technique. The fixed-order calculation is carried out numerically with the NNLO jet parton-level event generator, using the antenna subtraction method. We perform detailed cross-validation in the two-particle region, demonstrating that the expansion of the NNLL resummed result correctly reproduces the logarithmic structure of the fixed-order calculation to O(αₛ³) O α s 3 , up to a predictable N 3 LL term at O(αₛ³L) O α s 3 L . In addition to providing the first NNLO+NNLL accurate predictions for the thrust distribution in Higgs decays to quarks and gluons, we analytically extract the O(αₛ²) O α s 2 hard-virtual correction c 2 and the αₛ³L α s 3 L term G 31 in both the H→ qq̄ H → q q ¯ ( q = b , c ) and H → gg decay channels.