Measurement of k T splitting scales in W→ℓν events at $\sqrt{s} = 7\ \mathrm{TeV}$ with the ATLAS detector

Abstract

A measurement of splitting scales, as defined by the kT clustering algorithm, is presented for final states containing a W boson produced in proton–proton collisions at a centre-of-mass energy of 7 TeV. The measurement is based on the full 2010 data sample corresponding to an integrated luminosity of 36 pb−1 which was collected using the ATLAS detector at the CERN Large Hadron Collider. Cluster splitting scales are measured in events containing W bosons decaying to electrons or muons. The measurement comprises the four hardest splitting scales in a kT cluster sequence of the hadronic activity accompanying the W boson, and ratios of these splitting scales. Backgrounds such as multi-jet and top-quark-pair production are subtracted and the results are corrected for detector effects. Predictions from various Monte Carlo event generators at particle level are compared to the data. Overall, reasonable agreement is found with all generators, but larger deviations between the predictions and the data are evident in the soft regions of the splitting scales.

Right-handed charged currents in the era of the Large Hadron Collider

“…The first process we analyze to look for manifestations of RHCC is W ± production. This process is accurately measured at the LHC, both at the level of the inclusive cross section as well as for differential distributions [15][16][17][18][19][20][21][22][23][24][25]. Precise high-order calculations of the SM background are available up to fixed NNLO QCD corrections [26][27][28] and also include the resummation of the vector-boson transverse momentum [29,30].…”

Merging NLO multi-jet calculations with improved unitarization

“…These are resolution scales d i of the k T algorithm at which the event switches from an i jet event to an i + 1 jet event in W ± boson production. Figure 23 shows our simulated result of the √ d 0 distribution, compared to data from ATLAS [71]. We show W (0), W (0, 1, 2) and W (0 * , 1 * , 2) with the full event generator setup including MPI and hadronization effects.…”

“…A good example of an observable for which this [71]. While the MEs are needed to fill the phase space of hard emissions, the MPI model and hadronization are needed to model the lower scales of the spectrum Fig.…”

Studies of Quantum Chromodynamics at the LHC

“…From the analysis presented by CMS and a similar one presented by ATLAS [56], agreement of jetmass and substructure observables with modern parton-shower Monte Carlo tools is established. This paves the way to successfully use these techniques in future analyses and particularly in searches for new phenomena.…”