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P. Jenni and T. S. Virdee
Fig. 6.8 (a) The two-photon invariant mass distribution of selected candidates in the CMS
experiment, weighted by S/B of the category in which it falls. The lines represent the fitted
background and the expected signal contribution (m H = 125 GeV). (b) The four-lepton invariant
mass distribution in the ATLAS experiment for selected candidates relative to the background
expectation. The expected signal contribution (m H = 125 GeV) is also shown
be isolated. The pair with invariant mass closest to the Z boson mass is required to
have a mass in the range 40–120 GeV and the other pair is required to have a mass
in the range 12–120 GeV. The ZZ ( ∗ ) background, which is dominant, is evaluated
from Monte Carlo simulation studies.
The m 4l distribution is shown in Fig. 6.8b for the ATLAS experiment [19]. A
clear peak is observed at ~125 GeV in addition to the one at the Z mass. The latter
is due to the conversion of an inner bremstrahlung photon emitted simultaneously
with the dilepton pair. A similar result was obtained by the CMS experiment [20].
6.7.2.3 Combinations
A search was also made in other decay modes of a possible Higgs boson and
combined to yield the final results published in August 2012 by ATLAS [19] and
CMS [20] experiments. Both ATLAS and CMS independently discovered a new
heavy boson at approximately the same mass, clearly evident in the two different
decay modes, γγ and ZZ ( ∗ ) . The observed (expected) local significances were 6.0σ
(5.0σ) and 5.0σ (5.8σ) in ATLAS and CMS respectively, indicating that a new
particle had been discovered.
The decay into two bosons (two photons; two Z bosons or two W bosons) implied
that the new particle is a boson with spin different from one, and its decay into two
photons that it carries either spin-0 or spin-2.
The results presented by both ATLAS and CMS collaborations were consistent,
within uncertainties, with the expectations for a SM Higgs boson. Both noted that
collection of more data would enable a more rigorous test of this conclusion and an
P. Jenni and T. S. Virdee
Fig. 6.8 (a) The two-photon invariant mass distribution of selected candidates in the CMS
experiment, weighted by S/B of the category in which it falls. The lines represent the fitted
background and the expected signal contribution (m H = 125 GeV). (b) The four-lepton invariant
mass distribution in the ATLAS experiment for selected candidates relative to the background
expectation. The expected signal contribution (m H = 125 GeV) is also shown
be isolated. The pair with invariant mass closest to the Z boson mass is required to
have a mass in the range 40–120 GeV and the other pair is required to have a mass
in the range 12–120 GeV. The ZZ ( ∗ ) background, which is dominant, is evaluated
from Monte Carlo simulation studies.
The m 4l distribution is shown in Fig. 6.8b for the ATLAS experiment [19]. A
clear peak is observed at ~125 GeV in addition to the one at the Z mass. The latter
is due to the conversion of an inner bremstrahlung photon emitted simultaneously
with the dilepton pair. A similar result was obtained by the CMS experiment [20].
6.7.2.3 Combinations
A search was also made in other decay modes of a possible Higgs boson and
combined to yield the final results published in August 2012 by ATLAS [19] and
CMS [20] experiments. Both ATLAS and CMS independently discovered a new
heavy boson at approximately the same mass, clearly evident in the two different
decay modes, γγ and ZZ ( ∗ ) . The observed (expected) local significances were 6.0σ
(5.0σ) and 5.0σ (5.8σ) in ATLAS and CMS respectively, indicating that a new
particle had been discovered.
The decay into two bosons (two photons; two Z bosons or two W bosons) implied
that the new particle is a boson with spin different from one, and its decay into two
photons that it carries either spin-0 or spin-2.
The results presented by both ATLAS and CMS collaborations were consistent,
within uncertainties, with the expectations for a SM Higgs boson. Both noted that
collection of more data would enable a more rigorous test of this conclusion and an