CMS-SUS-17-011

CMS-SUS-17-011 ; CERN-EP-2019-040
Search for supersymmetry in final states with photons and missing transverse momentum in proton-proton collisions at 13 TeV
CMS Collaboration
17 March 2019
JHEP 06 (2019) 143
Abstract: Results are reported for a search for supersymmetry in final states with photons and missing transverse momentum in proton-proton collisions at the LHC. The data sample corresponds to an integrated luminosity of 35.9 fb$^{-1}$ collected at a center-of-mass energy of 13 TeV using the CMS detector. The results are interpreted in the context of models of gauge-mediated supersymmetry breaking. Production cross section limits are set on gluino and squark pair production in this framework. Gluino masses below 1.86 TeV and squark masses below 1.59 TeV are excluded at 95% confidence level.
Links: e-print arXiv:1903.07070 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; CADI line (restricted) ;

Figures & Tables	Summary	References	CMS Publications

Figures
png pdf	Figure 1: Diagrams showing the production of signal events in the collision of two protons (p). In gluino (${\mathrm {\tilde{g}}}$) pair production in the T5gg simplified model (left), the gluino decays to a quark-antiquark pair (${\mathrm {q}} {\overline {\mathrm {q}}}$) and a neutralino (${\tilde{\chi}^{0}_{1}}$). In squark (${\mathrm {\tilde{q}}}$) pair production in the T6gg simplified model (right), the squark decays to a quark and a neutralino. In both cases, the neutralino subsequently decays to a photon (${\gamma}$) and a gravitino (${\mathrm{\tilde{G}}}$).
png pdf	Figure 1-a: Diagram showing the gluino (${\mathrm {\tilde{g}}}$) pair production in the collision of two protons (p), in the T5gg simplified model. The gluino decays to a quark-antiquark pair (${\mathrm {q}} {\overline {\mathrm {q}}}$) and a neutralino (${\tilde{\chi}^{0}_{1}}$). The neutralino subsequently decays to a photon (${\gamma}$) and a gravitino (${\mathrm{\tilde{G}}}$).
png pdf	Figure 1-b: Diagram showing the squark (${\mathrm {\tilde{q}}}$) pair production in the collision of two protons (p), in the T6gg simplified model. The squark decays to a quark and a neutralino. The neutralino subsequently decays to a photon (${\gamma}$) and a gravitino (${\mathrm{\tilde{G}}}$).
png pdf	Figure 2: The top panel shows the observed ${{p_{\mathrm {T}}} ^\text {miss}}$ distribution in data (black points) and predicted background distributions prior to the fit. The vertical line marks the boundary between the validation region ($ {{p_{\mathrm {T}}} ^\text {miss}} < $ 100 GeV) and the signal region ($ {{p_{\mathrm {T}}} ^\text {miss}} > $ 100 GeV). The last bin includes all events with $ {{p_{\mathrm {T}}} ^\text {miss}} > $ 250 GeV. The QCD background is shown in red, the EWK background is shown in blue, and the $ {\mathrm {Z}} {\gamma} {\gamma}$ background is shown in green. The ${{p_{\mathrm {T}}} ^\text {miss}}$ distribution shown in pink (purple) corresponds to the T5gg simplified model with $m_{{\mathrm {\tilde{g}}}}= $ 1700 (2000) GeV and $m_{{\tilde{\chi}^{0}_{1}}} = $ 1000 GeV. The bottom panel shows the ratio of observed events to the expected background. The error bars on the ratio correspond to the statistical uncertainty in the number of observed events. The shaded region corresponds to the total uncertainty in the background estimate.
png pdf	Figure 3: The 95% confidence level upper limits on the gluino (left) and squark (right) pair production cross sections as a function of gluino or squark and neutralino masses. The contours show the observed and expected exclusions assuming the NLO+NLL cross sections, with their one standard deviation uncertainties.
png pdf	Figure 3-a: The 95% confidence level upper limits on the gluino pair production cross sections as a function of gluino and neutralino masses. The contours show the observed and expected exclusions assuming the NLO+NLL cross sections, with their one standard deviation uncertainties.
png pdf	Figure 3-b: The 95% confidence level upper limits on the squark pair production cross sections as a function of squark and neutralino masses. The contours show the observed and expected exclusions assuming the NLO+NLL cross sections, with their one standard deviation uncertainties.

Tables
png pdf	Table 1: Event yield and statistical and systematic uncertainties (in numbers of events) in the QCD background estimation for each signal ${{p_{\mathrm {T}}} ^\text {miss}}$ bin.
png pdf	Table 2: Number of expected background and observed data events in the signal region prior to the fit defined in the text. The uncertainty in each expected background yield includes the statistical uncertainty and all of the systematic uncertainties described in Section 5 added in quadrature.

Summary

The results of a search for general gauge-mediated supersymmetry breaking in proton-proton collisions with two photons and missing transverse momentum in the final state are reported. The analysis was performed using data corresponding to 35.9 fb$^{-1}$ of integrated luminosity, recorded with the CMS detector in 2016 at a proton-proton center-of-mass energy of 13 TeV. An excess of events corresponding to 2.4 standard deviations is observed. Limits are determined on the masses of supersymmetric particles in two simplified models using data-driven background estimation methods and NLO+NLL signal cross section calculations.

In both models, the next-to-lightest supersymmetric particle is the neutralino, which decays with a 100% branching fraction to a photon and a gravitino, the lightest supersymmetric particle. The first simplified model assumes gluino pair production, with each gluino decaying to a neutralino and quarks. The second simplified model assumes squark pair production, with each squark decaying to a quark and a neutralino. The expected limits on gluino and squark masses, for the respective models, are 2.02 and 1.74 TeV at 95% confidence level. This is an increase in sensitivity of more than 300 GeV for each model with respect to the analysis performed with 2.3 fb$^{-1}$ of integrated luminosity collected using the CMS detector in 2015. The observed exclusions are for gluino masses less than 1.86 TeV and squark masses less than 1.59 TeV, where the difference between the expected and observed exclusions is driven by the excess observed in the data. The analysis described in this paper improves the observed limits by 210 GeV for gluino masses and 220 GeV for squark masses with respect to the previous CMS result.

References
1	C. R. Nappi and B. A. Ovrut	Supersymmetric extension of the SU(3)$ \times $SU(2)$ \times $U(1) model	PLB 113 (1982) 175
2	M. Dine and W. Fischler	A phenomenological model of particle physics based on supersymmetry	PLB 110 (1982) 227
3	L. Alvarez-Gaum\'e, M. Claudson, and M. B. Wise	Low-energy supersymmetry	Nuc. Phys. B 207 (1982) 96
4	M. Dine and A. E. Nelson	Dynamical supersymmetry breaking at low-energies	PRD 48 (1993) 1277	hep-ph/9303230
5	M. Dine, A. E. Nelson, and Y. Shirman	Low-energy dynamical supersymmetry breaking simplified	PRD 51 (1995) 1362	hep-ph/9408384
6	M. Dine, A. E. Nelson, Y. Nir, and Y. Shirman	New tools for low-energy dynamical supersymmetry breaking	PRD 53 (1996) 2658	hep-ph/9507378
7	R. Barbieri and G. F. Giudice	Upper bounds on supersymmetric particle masses	NPB 306 (1988) 63
8	S. Dimopoulos, G. F. Giudice, and A. Pomarol	Dark matter in theories of gauge-mediated supersymmetry breaking	PLB 389 (1996) 37	hep-ph/9607225
9	S. P. Martin	Generalized messengers of supersymmetry breaking and the sparticle mass spectrum	PRD 55 (1997) 3177	hep-ph/9608224
10	E. Poppitz and S. P. Trivedi	Some remarks on gauge-mediated supersymmetry breaking	PLB 401 (1997) 38	hep-ph/9703246
11	P. Meade, N. Seiberg, and D. Shih	General gauge mediation	Prog. Theor. Phys. Suppl. 177 (2009) 143	0801.3278
12	M. Buican, P. Meade, N. Seiberg, and D. Shih	Exploring general gauge mediation	JHEP 03 (2009) 016	0812.3668
13	S. Abel, M. J. Dolan, J. Jaeckel, and V. V. Khoze	Phenomenology of pure general gauge mediation	JHEP 12 (2009) 001	0910.2674
14	L. M. Carpenter, M. Dine, G. Festuccia, and J. D. Mason	Implementing general gauge mediation	PRD 79 (2009) 035002	0805.2944
15	T. T. Dumitrescu, Z. Komargodski, N. Seiberg, and D. Shih	General messenger gauge mediation	JHEP 05 (2010) 96	1003.2661
16	G. R. Farrar and P. Fayet	Phenomenology of the production, decay, and detection of new hadronic states associated with supersymmetry	PLB 76 (1978) 37
17	CMS Collaboration	Search for supersymmetry in events with photons and missing transverse energy in pp collisions at 13 TeV	PLB 769 (2017) 391	1611.06604
18	ATLAS Collaboration	Search for supersymmetry in a final state containing two photons and missing transverse momentum in $ \sqrt{s} = $ 13 TeV pp collisions at the LHC using the ATLAS detector	EPJC 76 (2016) 517	1606.09150
19	ATLAS Collaboration	Search for photonic signatures of gauge-mediated supersymmetry in 13 TeV pp collisions with the ATLAS detector	PRD 97 (2018) 092006	1802.03158
20	N. Arkani-Hamed et al.	MARMOSET: The path from LHC data to the new standard model via on-shell effective theories		hep-ph/0703088
21	J. Alwall, P. C. Schuster, and N. Toro	Simplified models for a first characterization of new physics at the LHC	PRD 79 (2009) 075020	0810.3921
22	J. Alwall, M.-P. Le, M. Lisanti, and J. G. Wacker	Model-independent jets plus missing energy searches	PRD 79 (2009) 015005	0809.3264
23	D. Alves et al.	Simplified models for LHC new physics searches	JPG 39 (2012) 105005	1105.2838
24	CMS Collaboration	Interpretation of searches for supersymmetry with simplified models	PRD 88 (2013) 052017	CMS-SUS-11-016 1301.2175
25	CMS Collaboration	The CMS experiment at the CERN LHC	JINST 3 (2008) S08004	CMS-00-001
26	CMS Collaboration	The CMS trigger system	JINST 12 (2017) P01020	CMS-TRG-12-001 1609.02366
27	J. Alwall et al.	The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations	JHEP 07 (2014) 079	1405.0301
28	T. Sjostrand, S. Mrenna, and P. Z. Skands	A brief introduction to PYTHIA 8.1	CPC 178 (2008) 852	0710.3820
29	CMS Collaboration	Event generator tunes obtained from underlying event and multiparton scattering measurements	EPJC 76 (2016) 155	1512.00815v2
30	NNPDF Collaboration	Parton distributions for the LHC Run II	JHEP 04 (2015) 040	1410.8849
31	GEANT4 Collaboration	GEANT4--a simulation toolkit	NIMA 506 (2003) 250
32	CMS Collaboration	The fast simulation of the CMS detector at LHC	J. Phys. Conf. Ser. 331 (2011) 032049
33	A. Giammanco	The fast simulation of the CMS experiment	J. Phys. Conf. Ser. 513 (2014) 022012
34	W. Beenakker, R. Hopker, M. Spira, and P. M. Zerwas	Squark and gluino production at hadron colliders	NPB 492 (1997) 51	hep-ph/9610490
35	A. Kulesza and L. Motyka	Threshold resummation for squark-antisquark and gluino-pair production at the LHC	PRL 102 (2009) 111802	0807.2405
36	A. Kulesza and L. Motyka	Soft gluon resummation for the production of gluino-gluino and squark-antisquark pairs at the LHC	PRD 80 (2009) 095004	0905.4749
37	W. Beenakker et al.	Soft-gluon resummation for squark and gluino hadroproduction	JHEP 12 (2009) 041	0909.4418
38	W. Beenakker et al.	Squark and gluino hadroproduction	Int. J. Mod. Phys. A 26 (2011) 2637	1105.1110
39	C. Borschensky et al.	Squark and gluino production cross sections in pp collisions at $ \sqrt{s} = $ 13, 14, 33 and 100 TeV	EPJC 74 (2014) 3174	1407.5066
40	CMS Collaboration	Particle-flow reconstruction and global event description with the CMS detector	JINST 12 (2017) P10003	CMS-PRF-14-001 1706.04965
41	CMS Collaboration	Performance of photon reconstruction and identification with the CMS detector in proton-proton collisions at $ \sqrt{s} = $ 8 TeV	JINST 10 (2015) P08010	CMS-EGM-14-001 1502.02702
42	CMS Collaboration	CMS luminosity measurements for the 2016 data taking period	CMS-PAS-LUM-17-001	CMS-PAS-LUM-17-001
43	T. Junk	Confidence level computation for combining searches with small statistics	NIMA 434 (1999) 435	hep-ex/9902006
44	A. L. Read	Presentation of search results: the $ CL_s $ technique	JPG 28 (2002) 2693
45	ATLAS and CMS Collaborations	Procedure for the LHC Higgs boson search combination in Summer 2011	CMS-NOTE-2011-005
46	G. Cowan, K. Cranmer, E. Gross, and O. Vitells	Asymptotic formulae for likelihood-based tests of new physics	EPJC 71 (2011) 1554	1007.1727