We present the complete calculation of W-boson production in association with a jet in hadronic collisions through next-to-next-to-leading order (NNLO) in perturbative QCD. To cancel infrared divergences, we discuss a new subtraction method that exploits the fact that the N-jettiness event-shape variable fully captures the singularity structure of QCD amplitudes with final-state partons. This method holds for processes with an arbitrary number of jets and is easily implemented into existing frameworks for higher-order calculations. We present initial phenomenological results for W+jet production at the LHC. The NNLO corrections are small and lead to a significantly reduced theoretical error, opening the door to precision measurements in the W+jet channel at the LHC.

We use the recently proposed jettiness-subtraction scheme to provide the complete calculation of Higgs boson production in association with a jet in hadronic collisions through next-to-nextto-leading order in perturbative QCD. This method exploits the observation that the N -jettiness event-shape variable completely describes the singularity structure of QCD when final-state colored particles are present. Our results are in agreement with a recent computation of the gg and qg partonic initial states based on sector-improved residue subtraction. We present phenomenological results for both fiducial cross sections and distributions at the LHC.

We present the first complete calculation of Z-boson production in association with a jet in hadronic collisions through next-to-next-to-leading order in perturbative QCD. Our computation uses the recently-proposed N -jettiness subtraction scheme to regulate the infrared divergences that appear in the real-emission contributions. We present phenomenological results for 13 TeV protonproton collisions with fully realistic fiducial cuts on the final-state particles. The remaining theoretical uncertainties after the inclusion of our calculations are at the percent-level, making the Z+jet channel ready for precision studies at the LHC Run II.

Abstract:We discuss the leading-logarithmic power corrections in the N -jettiness subtraction scheme for higher-order perturbative QCD calculations. We compute the next-toleading order power corrections for an arbitrary N -jet process, and we explicitly calculate the power correction through next-to-next-to-leading order for color-singlet production for both qq and gg initiated processes. Our results are compact and simple to implement numerically. Including the leading power correction in the N -jettiness subtraction scheme substantially improves its numerical efficiency. We discuss what features of our techniques extend to processes containing final-state jets.

This paper presents a detailed experimental study of random lasers with resonant feedback. The dependences of the lasing threshold and the number of lasing modes on the transport mean free path, the pump area, and the sample size are measured. An analytical model based on the concept of quasistates is developed to explain the behaviors of random lasers.

We present a general framework for the calculation of soft functions for SCET I observables through next-to-next-to-leading order (NNLO) in the strong coupling constant. As an example of our formalism we show how it can be used to obtain the complete NNLO soft function for the N -jettiness event shape variable. We present numerical results for two examples with phenomenological impact: the one-jettiness soft function for both electron-proton and proton-proton collisions.

We study the transverse momentum distribution of hadrons within jets, where the transverse momentum is defined with respect to the standard jet axis. We consider the case where the jet substructure measurement is performed for an inclusive jet sample pp → jet + X. We demonstrate that this observable provides new opportunities to study transverse momentum dependent fragmentation functions (TMDFFs) which are currently poorly constrained from data, especially for gluons. The factorization of the cross section is obtained within Soft Collinear Effective Theory (SCET), and we show that the relevant TMDFFs are the same as for the more traditional processes semi-inclusive deep inelastic scattering (SIDIS) and electron-positron annihilation. Different than in SIDIS, the observable for the in-jet fragmentation does not depend on TMD parton distribution functions which allows for a cleaner and more direct probe of TMDFFs. We present numerical results and compare to available data from the LHC.

We derive a factorization theorem for production of an arbitrary number of colorsinglet particles accompanied by a fixed number of jets at the LHC. The jets are defined with the standard anti-k T algorithm, and the fixed number of jets is obtained by imposing a veto on additional radiation in the final state. The formalism presented here is useful for current Higgs boson analyses using exclusive jet bins, and for other studies using a similar strategy. The derivation uses the soft-collinear effective theory and assumes that the transverse momenta of the hard jets are larger than the veto scale. We resum the large Sudakov logarithms α n s log 2n−m p J T /p veto T up to the next-toleading-logarithmic accuracy, and present numerical results for Higgs boson production in association with a jet at the LHC. We comment on the experimentally-interesting parameter region in which we expect our factorization formula to hold.