Hadronisation corrections for jets in the k_t algorithm

It has recently been established that hadronisation corrections to QCD jets vary as $1/R$, at small $R$, for jets of radius $R$. Here we demonstrate, using jets in the $k_t$ algorithm, that the magnitude of these $1/R$ corrections are unambiguously linked to the magnitude of $1/Q$ corrections to commonly studied event shapes in $e^{+}e^{-}$ annihilation.Comment: Presented at DIS 2009, Madrid, Spai

Non-global logarithms at finite Nc beyond leading order

We analytically compute non-global logarithms at finite Nc fully up to 4 loops and partially at 5 loops, for the hemisphere mass distribution in e+e- to di-jets to leading logarithmic accuracy. Our method of calculation relies solely on integrating the eikonal squared-amplitudes for the emission of soft energy-ordered real-virtual gluons over the appropriate phase space. We show that the series of non-global logarithms in the said distribution exhibits a pattern of exponentiation thus confirming - by means of brute force - previous findings. In the large-Nc limit, our results coincide with those recently reported in literature. A comparison of our proposed exponential form with all-orders numerical solutions is performed and the phenomenological impact of the finite-Nc corrections is discussed.Comment: 31 pages, 5 figure, uses jheppub.sty, minor corrections to previous version and added some reference

Jet mass distribution in Higgs/vector boson + jet events at hadron colliders with ktk_t clustering

We address the issues of clustering and non-global logarithms for jet shapes in the process of production of a Higgs/vector boson associated with a single hard jet at hadron colliders. We perform an analytical fixed-order calculation up to second order in the coupling as well as an all-orders estimation for the specific invariant mass distribution of the highest-$p_t$ jet, for various jet algorithms. Our results are derived in the eikonal (soft) limit and are valid up to next-to-leading logarithmic accuracy. We perform a matching of the resummed distribution to next-to-leading order results from MCFM and compare our findings with the outputs of the Monte Carlo event generators Pythia 8 and Herwig 7. After accounting for non-perturbative effects we compare our results with available experimental data from the CMS collaboration for the Z + jet production. We find good agreement over a wide range of the observable.Comment: 18 pages, 14 figure

Higgs ptp_t distribution in Higgs + jet production at hadron colliders within the non-commutative Higgs effective standard model

We use the non-commutative Higgs effective standard model to make a phenomenological prediction for the transverse momentum distribution of the Higgs boson produced in association with a jet at hadron colliders. We calculate at leading order in the non-commutative parameter $\Theta$ as well as leading order in the strong coupling $\alpha_s$, the one-loop $p_t$ distribution of the Higgs boson. As in the standard model, the fixed-order distribution suffers from large logarithms at small $p_t$ which require an all-orders resummation. We find that the large-$p_t$ region of the distribution is strongly affected by the non-commutativity, while small-$p_t$ region is not. Following this observation, we propose a simple matching method that allows us to compute a result that is also valid at small $p_t$ obtained with standard-model parton showers such as Pythia 8.Comment: 9 pages, 3 figure