The CMS Collaboration / Physics Letters B 769 (2017) 391–412 395
Table 2
Numbers
of expected and observed events in the signal region. The last row shows the total number of
expected and observed events in the inclusive bin E
miss
T
≥ 100 GeV. The expected numbers of events for
two T5gg mass points are also shown. For Signal A, M
g
= 1400 GeV and M
χ
0
1
= 600 GeV. For Signal B,
M
g
= 1600 GeV and M
χ
0
1
= 600 GeV. The uncertainties include all of the systematic uncertainties described
in Section 5.
E
miss
T
bin (GeV) QCD EWK Total background Signal A Signal B Observed
100 ≤ E
miss
T
< 110 1.9±1.0 0.4±0.1 2.3±1.0 0.12±0.01 0.04±0.01 4
110
≤ E
miss
T
< 120 1.5±0.6 0.3±0.1 1.8±0.6 0.13±0.02 0.04±0.01 2
120
≤ E
miss
T
< 140 1.0±0.6 0.5±0.2 1.5±0.6 0.31±0.04 0.08±0.01 2
E
miss
T
≥ 140 0.6±2.2 1.0±0.3 1.6±2.2 13.0±0.7 4.4±0.2 1
E
miss
T
≥ 100 5.0±2.5 2.2±0.3 7.2±2.5 13.6±0.7 4.6±0.2 9
Fig. 4. The 95% CL upper limits on the gluino (top) and squark (bottom) pair produc-
tion
cross sections as a function of neutralino versus gluino (squark) mass. The con-
tours
show the observed and median expected exclusions assuming the NLO+NLL
cross sections, with their one standard deviation uncertainties. The limit curves ter-
minate
at the centers of the bins used to sample the cross section.
tion 5 are included in the test statistic as nuisance parameters,
with log-normal probability distributions.
In
Fig. 4 we present 95% CL upper limits on the cross section as
a function of the mass pair values for the two models considered
in this analysis, M
χ
0
1
versus M
g
and M
χ
0
1
versus M
q
for gluino
pair and squark pair production, respectively. From the NLO+NLL
predicted cross sections and their uncertainties we derive contours
representing lower limits in the SUSY mass plane. We also show
expected limit contours based on the expected experimental cross
section limits and their uncertainties. For typical values of the neu-
tralino
mass, we expect to exclude gluino masses up to 1.60 TeV
and
squark masses up to 1.35 TeV, and we observe exclusions of
1.65 and 1.37 TeV respectively. The excluded mass ranges for gluino
pair production have been improved by approximately 300 GeV
with respect to previous searches performed at
√
s = 8TeV[15,
16].
The observed exclusions are consistent with the results of the
ATLAS analysis performed at
√
s =13 TeV [17].
7. Summary
A search is performed for supersymmetry with general gauge
mediation in proton–proton collisions yielding events with two
photons and large missing transverse energy. The data were col-
lected
at a center-of-mass energy of 13 TeV with the CMS detector
in 2015, and correspond to an integrated luminosity of 2.3 fb
−1
.
The
data are interpreted in the context of two simplified SUSY
models with gauge-mediated supersymmetry breaking, one assum-
ing
gluino pair production and the second assuming squark pair
production. In both models, the branching fraction of the NLSP
neutralino to decay to a gravitino and a photon is assumed to
be unity. Using background estimation methods based on control
samples in data, limits are determined on the gluino and squark
pair production cross sections, and those limits are used together
with NLO+NLL cross section calculations to constrain the masses
of gluinos, squarks, and neutralinos. Gluino masses below 1.65 TeV
and
squark masses below 1.37 TeV are excluded at a 95% con-
fidence
level. This represents an improvement of approximately
300 GeV with respect to previous analyses performed at a center-
of-mass
energy of 8TeV[15,16] and is consistent with the results
of the ATLAS analysis performed at a center-of-mass energy of
13 TeV [17].
Acknowledgements
We congratulate our colleagues in the CERN accelerator de-
partments
for the excellent performance of the LHC and thank
the technical and administrative staffs at CERN and at other CMS
institutes for their contributions to the success of the CMS ef-
fort.
In addition, we gratefully acknowledge the computing centres
and personnel of the Worldwide LHC Computing Grid for deliv-
ering
so effectively the computing infrastructure essential to our
analyses. Finally, we acknowledge the enduring support for the
construction and operation of the LHC and the CMS detector pro-
vided
by the following funding agencies: BMWFW and FWF (Aus-
tria);
FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP
(Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China);
COLCIENCIAS (Colombia); MSES and CSF (Croatia); RPF (Cyprus);
SENESCYT (Ecuador); MoER, ERC IUT, and ERDF (Estonia); Academy
of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France);
BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NIH
(Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN
(Italy); MSIP and NRF (Republic of Korea); LAS (Lithuania); MOE
and UM (Malaysia); BUAP, CINVESTAV, CONACYT, LNS, SEP, and
UASLP-FAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE
and NSC (Poland); FCT (Portugal); JINR (Dubna); MON, RosAtom,