Measurement of the transverse momentum spectrum of the Higgs boson produced in pp collisions at \( \sqrt{s}=8 \) TeV using H → WW decays
Received: June
decays
The CMS collaboration 0 1 2 3 4 5
0 [56] S. Alioli , P. Nason, C. Oleari and E. Re, NLO Higgs boson production via gluon fusion
1 Chulalongkorn University, Faculty of Science, Department of Physics , Bangkok
2 State University of New York at Bu alo , Bu alo , U.S.A
3 (MEPhI) , Moscow , Russia
4 15: Also at Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University
5 59: Also at Istanbul Bilgi University , Istanbul , Turkey
The cross section for Higgs boson production in pp collisions is studied using
Hadron-Hadron scattering (experiments); Higgs physics
-
decay mode, followed by leptonic decays of the W bosons to an
oppositely charged electron-muon pair in the
nal state. The measurements are performed
using data collected by the CMS experiment at the LHC at a centre-of-mass energy of
8 TeV, corresponding to an integrated luminosity of 19.4 fb 1. The Higgs boson transverse
momentum (pT) is reconstructed using the lepton pair pT and missing pT. The di erential
cross section times branching fraction is measured as a function of the Higgs boson pT in a
ducial phase space de ned to match the experimental acceptance in terms of the lepton
kinematics and event topology. The production cross section times branching fraction in
ducial phase space is measured to be 39
9 (syst) fb. The measurements
are found to agree, within experimental uncertainties, with theoretical calculations based
on the standard model.
1 Introduction
The CMS experiment
Data and simulated samples
Analysis strategy
Background estimation
Systematic uncertainties
Signal extraction
The CMS collaboration
Unfolding and treatment of systematic uncertainties
The discovery of a new boson at the CERN LHC reported by the ATLAS and CMS
collaborations [1{3] has been followed by a comprehensive set of measurements aimed at
establishing the properties of the new boson. Results reported by ATLAS and CMS [4{22],
so far, are consistent with the standard model (SM) expectations for the Higgs boson (H).
Measurements of the production cross section of the Higgs boson times branching
fraction in a restricted part of the phase space ( ducial phase space) and its kinematic
properties represent an important test for possible deviations from the SM predictions. In
particular, it has been shown that the Higgs boson transverse momentum (pTH) spectrum
can be signi cantly a ected by the presence of interactions not predicted by the SM [23{27].
In addition, these measurements allow accurate tests of the theoretical calculations in the
SM Higgs sector, which o er up to next-to-next-to-leading-order (NNLO) accuracy in
perturbative Quantum ChromoDynamics (pQCD), up to next-to-next-to-leading-logarithmic
(NNLL) accuracy in the resummation of soft-gluon e ects at small pT, and up to
next-toleading-order (NLO) accuracy in perturbative electroweak corrections [28{30].
Measurements of the
ducial cross sections and of several di erential distributions,
for the H ! ZZ ! 4` (` = e; ) and H !
decay channels, and recently by ATLAS [36]
decay channel. In this paper we report a measurement of
the ducial cross section times branching fraction (
production in H ! W+W
decays, based on p
B) and pT spectrum for Higgs boson
s = 8 TeV LHC data. The
analysis is performed looking at di erent avour leptons in the nal state in order to suppress
the sizeable contribution of backgrounds containing a same- avour lepton pair originating
from Z boson decay. Although the H ! W+W
the pTH measurement compared to the H !
! 2`2 channel has lower resolution in
and H ! ZZ ! 4` channels because of
neutrinos in the nal state, the channel has a signi cantly larger
B, exceeding those for
by a factor of 10 and H ! ZZ ! 4` by a factor of 85 for a Higgs boson mass of
125 GeV [37], and is characterized by good signal sensitivity. Such sensitivity allowed the
observation of a Higgs boson at the level of 4.3 (5.8 expected) standard deviations for a
mass hypothesis of 125.6 GeV using the full LHC data set at 7 and 8 TeV [7].
The measurement is performed in a ducial phase space de ned by kinematic
requirements on the leptons that closely match the experimental event selection. The e ect of the
limited detector resolution, as well as the selection e ciency with respect to the
phase space are corrected to particle level with an unfolding procedure [38]. This procedure
is based on the knowledge of the detector response matrix, derived from the simulation of
the CMS response to signal events, and consists of an inversion of the response matrix with a
regularization prescription to tame unphysical statistical uctuations in the unfolded result.
The analysis presented here is based on the previously published H ! W+W
measurements by CMS [7]. A notable di erence from those measurements is that this
analysis is inclusive in the number of jets, which allows the uncertainties related to the
theoretical modelling of additional jets produced in association with the Higgs boson to
b (...truncated)