We present predictions for Higgs production via gluon fusion with a p T veto on jets and with the resummation of jet-veto logarithms at NNLL 0 þ NNLO order. These results incorporate explicit Oðα 2 s Þ calculations of soft and beam functions, which include the dominant dependence on the jet radius R. In particular the NNLL 0 order accounts for the correct boundary conditions for the N 3 LL resummation, for which the only unknown ingredients are higher-order anomalous dimensions. We use scale variations in a factorization theorem in both rapidity and virtuality space to estimate the perturbative uncertainties, accounting for both higher fixed-order corrections as well as higher-order towers of jet-p T logarithms. This formalism also predicts the correlations in the theory uncertainty between the exclusive 0-jet and inclusive 1-jet bins. At the values of R used experimentally, there are important corrections due to jet algorithm clustering that include logarithms of R. Although we do not sum logarithms of R, we do include an explicit contribution in our uncertainty estimate to account for higher-order jet clustering logarithms. Precision predictions for this H þ 0-jet cross section and its theoretical uncertainty are an integral part of Higgs analyses that employ jet binning.

Multijet cross sections at the LHC and Tevatron are sensitive to several distinct kinematic energy scales. When measuring the dijet invariant mass mjj between two signal jets produced in association with other jets or weak bosons, mjj will typically be much smaller than the total partonic centerof-mass energy Q, but larger than the individual jet masses m, such that there can be a hierarchy of scales m ≪ mjj ≪ Q. This situation arises in many new-physics analyses at the LHC, where the invariant mass between jets is used to gain access to the masses of new-physics particles in a decay chain. At present, the logarithms arising from such a hierarchy of kinematic scales can only be summed at the leading-logarithmic level provided by parton-shower programs. We construct an effective field theory, SCET+, which is an extension of Soft-Collinear Effective Theory that applies to this situation of hierarchical jets. It allows for a rigorous separation of different scales in a multiscale soft function and for a systematic resummation of logarithms of both mjj /Q and m/Q. As an explicit example, we consider the invariant mass spectrum of the two closest jets in e + e − → 3 jets. We also give the generalization to pp → N jets plus leptons relevant for the LHC.

Jet vetoes play an important role at the LHC in the search for the Higgs and ultimately in precise measurements of its properties. Many Higgs analyses divide the cross section into exclusive jet bins to maximize the sensitivity in different production and decay channels. For a given jet category, the veto on additional jets introduces sensitivity to soft and collinear emissions, which causes logarithms in the perturbative expansion that need to be resummed to obtain precise predictions. We study the higher-order resummation properties of several conceptually distinct kinematic variables that can be used to veto jets in hadronic collisions. We consider two inclusive variables, the scalar sum over pT and beam thrust, and two corresponding exclusive variables based on jet algorithms, namely the largest pT and largest beam thrust of a jet. The inclusive variables can in principle be resummed to higher orders. We show that for the jet-based variables, there are dual effects due to clustering in the jet algorithm for both large and small jet radius R that inhibit a complete resummation at or beyond next-to-leading logarithmic order (NLL). For R ∼ 1, the clustering of soft and collinear emissions gives O(1) contributions starting at NNLL that are not reproduced by an all-order softcollinear factorization formula and therefore cannot be resummed by it. For R 1, clustering induces logarithms of R that contribute at NLL in the exponent of the cross section, which cannot be resummed with currently available methods. We explicitly compute the leading jet clustering effects at O(α 2 s ) and comment on their numerical size.