CMS-PAS-SUS-16-046

CMS-PAS-SUS-16-046
Search for GMSB supersymmetry in events with at least one photon and missing transverse momentum in pp collisions at $\sqrt{s} =$ 13 TeV
CMS Collaboration
March 2017

Abstract: A search for supersymmetry with gauge-mediated supersymmetry breaking in electroweak and strong production and final states with photons and large missing transverse momentum is presented in this note. The data sample was collected in 2016 in pp collisions at $\sqrt{s} =$ 13 TeV with the CMS detector at the LHC and corresponds to an integrated luminosity of 35.9 fb $^{-1}$ . Scenarios are studied, in which the lightest neutralino has bino- or wino-like components, resulting in decays to photons and gravitinos, where the gravitinos escape undetected. The event selection was optimised for high sensitivity to both electroweak and strong production SUSY scenarios. No indication for the presence of new physics is observed. The analysis excludes gaugino masses below 750 GeV at the 95% confidence level in a simplified model with electroweak production of mass-degenerate charginos and neutralinos and sets stringent limits in four strong production simplified models based on gluino and squark pair-production. The analysis currently sets the most stringent limits in the electroweak model studied and in the compressed mass phase space of the strong production models.
Links: CDS record (PDF) ; inSPIRE record ; CADI line (restricted) ; These preliminary results are superseded in this paper, PLB 780 (2018) 118. The superseded preliminary plots can be found here.

Figures & Tables	Summary	Additional Figures & Tables	References	CMS Publications

Additional information on efficiencies needed for reinterpretation of these results are available here.
Additional technical material for CMS speakers can be found here.

Figures
png pdf	Figure 1: In the TChiWg scenario, the gauginos are mass-degenerate, and the $\tilde{ \chi }^0 _1$ decays as $\tilde{ \chi }^0 _1\to \gamma \tilde{ \mathrm{G} }$ and the chargino decays as $\tilde{ \chi }^{\pm} _1\to \mathrm {W}^{\pm }\tilde{ \mathrm{G} }$ .
png pdf	Figure 2: For strong gluino pair-production the simplified scenarios T5gg (a) and T5Wg (b) and for squark pair-production the simplified scenarios T6gg (c) and T6Wg (d) are studied. The neutralino decays as $\tilde{ \chi }^0 _1\to \gamma \tilde{ \mathrm{G} }$ , while the chargino decays as $\tilde{ \chi }^{\pm} _1\to \mathrm {W}^{\pm }\tilde{ \mathrm{G} }$ . In the T5Wg and T6Wg scenario, a branching ratio of 50% is assumed for the decays $\tilde{\text {g}}\rightarrow \mathrm{qq}\tilde{ \chi }^{\pm} _1$ and $\tilde{\text {g}}\rightarrow \mathrm{qq}\tilde{ \chi }^0 _1$ , and $\tilde{\text {q}}\rightarrow \mathrm{q}\tilde{ \chi }^{\pm} _1$ and $\tilde{\text {q}}\rightarrow \mathrm{q}\tilde{ \chi }^0 _1$ , respectively.
png pdf	Figure 2-a: For strong gluino pair-production the simplified scenario T5gg is studied. The neutralino decays as $\tilde{ \chi }^0 _1\to \gamma \tilde{ \mathrm{G} }$ .
png pdf	Figure 2-b: For strong gluino pair-production the simplified scenario T5Wg is studied. The neutralino decays as $\tilde{ \chi }^0 _1\to \gamma \tilde{ \mathrm{G} }$ , while the chargino decays as $\tilde{ \chi }^{\pm} _1\to \mathrm {W}^{\pm }\tilde{ \mathrm{G} }$ . A branching ratio of 50% is assumed for the decays $\tilde{\text {g}}\rightarrow \mathrm{qq}\tilde{ \chi }^{\pm} _1$ and $\tilde{\text {g}}\rightarrow \mathrm{qq}\tilde{ \chi }^0 _1$ , and $\tilde{\text {q}}\rightarrow \mathrm{q}\tilde{ \chi }^{\pm} _1$ and $\tilde{\text {q}}\rightarrow \mathrm{q}\tilde{ \chi }^0 _1$ , respectively.
png pdf	Figure 2-c: For squark pair-production the simplified scenario T6gg is studied. The neutralino decays as $\tilde{ \chi }^0 _1\to \gamma \tilde{ \mathrm{G} }$ .
png pdf	Figure 2-d: For squark pair-production the simplified scenario T6Wg is studied. The neutralino decays as $\tilde{ \chi }^0 _1\to \gamma \tilde{ \mathrm{G} }$ , while the chargino decays as $\tilde{ \chi }^{\pm} _1\to \mathrm {W}^{\pm }\tilde{ \mathrm{G} }$ . A branching ratio of 50% is assumed for the decays $\tilde{\text {g}}\rightarrow \mathrm{qq}\tilde{ \chi }^{\pm} _1$ and $\tilde{\text {g}}\rightarrow \mathrm{qq}\tilde{ \chi }^0 _1$ , and $\tilde{\text {q}}\rightarrow \mathrm{q}\tilde{ \chi }^{\pm} _1$ and $\tilde{\text {q}}\rightarrow \mathrm{q}\tilde{ \chi }^0 _1$ , respectively.
png pdf	Figure 3: Template fit result. The post-fit distributions for $\gamma$ +jets (blue) and V(+ $\gamma$ ) (orange) together with the fixed background (magenta) and the total fit distribution stacked onto the fixed backgrounds (red) are shown. The statistical uncertainty of the post-fit distribution is shown in the red hatched area and the systematic uncertainty of the fixed background is indicated with the magenta hatched area. The values in the legend are the resulting scale factors. The pull distribution only considers the statistical uncertainty. Systematic uncertainties are not included and especially cover the deviations for low and high values of ${\Delta \phi ( p_{\mathrm{T}}^{\text{miss}} ,\text {nearest jet}/\gamma )}$ .
png pdf	Figure 4: Validation of the electron misidentification background estimation method using MC simulation. In the selection with at least one photon with ${p_{\mathrm {T}}} >$ 100 GeV the $\text {e}\to \gamma$ estimation method is compared to direct simulation in the photon transverse momentum (a) and the $p_{\mathrm{T}}^{\text{miss}}$ distribution (b). Events populating the phase space beyond the shown range are included in the last bin. The bin contents are divided by the bin widths.
png pdf	Figure 4-a: Validation of the electron misidentification background estimation method using MC simulation. In the selection with at least one photon with ${p_{\mathrm {T}}} >$ 100 GeV the $\text {e}\to \gamma$ estimation method is compared to direct simulation in the photon transverse momentum distribution. Events populating the phase space beyond the shown range are included in the last bin. The bin contents are divided by the bin widths.
png pdf	Figure 4-b: Validation of the electron misidentification background estimation method using MC simulation. In the selection with at least one photon with ${p_{\mathrm {T}}} >$ 100 GeV the $\text {e}\to \gamma$ estimation method is compared to direct simulation in the $p_{\mathrm{T}}^{\text{miss}}$ distribution. Events populating the phase space beyond the shown range are included in the last bin. The bin contents are divided by the bin widths.
png pdf	Figure 5: Data to simulation comparisons in the control region (left) and the validation region (right). In the left plot, events with ${S_{\mathrm {T}}^{\gamma } }$ beyond the shown range are included in the last bin. The bin contents are divided by the shown bin widths.
png pdf	Figure 5-a: Data to simulation comparisons in the control region. Events with ${S_{\mathrm {T}}^{\gamma } }$ beyond the shown range are included in the last bin. The bin contents are divided by the shown bin widths.
png pdf	Figure 5-b: Data to simulation comparisons in the validation region. The bin contents are divided by the shown bin widths.
png pdf	Figure 6: Comparison of measurement and prediction in the signal region in four exclusive bins of ${S_{\mathrm {T}}^{\gamma } }$ . For guidance, two SUSY benchmark signal points are stacked on the SM background prediction, where the TChiWG SUSY signal point corresponds to a NLSP mass of 700 GeV and the T5Wg signal point corresponds to a gluino mass of 1750 GeV and a NLSP mass of 1700 GeV. Events with values of ${S_{\mathrm {T}}^{\gamma } }$ beyond the shown range are included in the last bin.
png pdf root	Figure 7: Observed and expected upper cross section limits as a function of the NLSP mass for the TChiWg model together with the corresponding theoretical cross section.
png pdf	Figure 8: The 95% CL limits for the T5gg and T5Wg SMS models in the gluino-neutralino/chargino mass plane. The color scale encodes the observed upper cross section limit for each point. The lines represent the observed (black) and expected (red) exclusion contours and their uncertainties.
png pdf root	Figure 8-a: The 95% CL limits for the T5gg SMS model in the gluino-neutralino/chargino mass plane. The color scale encodes the observed upper cross section limit for each point. The lines represent the observed (black) and expected (red) exclusion contours and their uncertainties.
png pdf root	Figure 8-b: The 95% CL limits for the T5Wg SMS model in the gluino-neutralino/chargino mass plane. The color scale encodes the observed upper cross section limit for each point. The lines represent the observed (black) and expected (red) exclusion contours and their uncertainties.
png pdf	Figure 9: The 95% CL limits for the T6gg and T6Wg SMS model in the squark-neutralino/chargino mass plane. The color scale encodes the observed upper cross section limit for each point. The lines represent the observed (black) and expected (red) exclusion contours and their uncertainties.
png pdf root	Figure 9-a: The 95% CL limits for the T6gg SMS model in the squark-neutralino/chargino mass plane. The color scale encodes the observed upper cross section limit for each point. The lines represent the observed (black) and expected (red) exclusion contours and their uncertainties.
png pdf root	Figure 9-b: The 95% CL limits for the T6Wg SMS model in the squark-neutralino/chargino mass plane. The color scale encodes the observed upper cross section limit for each point. The lines represent the observed (black) and expected (red) exclusion contours and their uncertainties.
png pdf	Figure 10: Covariance and correlation matrices for the background prediction of the four signal region bins in ${S_{\mathrm {T}}^{\gamma } }$ .
png pdf	Figure 10-a: Covariance matrix for the background prediction of the four signal region bins in ${S_{\mathrm {T}}^{\gamma } }$ .
png pdf	Figure 10-b: Correlation matrix for the background prediction of the four signal region bins in ${S_{\mathrm {T}}^{\gamma } }$ .
png pdf	Figure 11: Significance plots for the electroweak production models TChiWg.
png pdf	Figure 12: Significance plots for the strong production models T5gg (top left), T5Wg (top right), T6gg (bottom left) and T6Wg (bottom right).
png pdf	Figure 12-a: Significance plots for the strong production model T5gg.
png pdf	Figure 12-b: Significance plots for the strong production model T5Wg.
png pdf	Figure 12-c: Significance plots for the strong production model T6gg.
png pdf	Figure 12-d: Significance plots for the strong production model T6Wg.

Tables
png pdf	Table 1: Systematic uncertainties of the individual backgrounds.
png pdf	Table 2: Systematic uncertainties of the electroweak and strong production SUSY signal scenarios.
png pdf	Table 3: Background and data yields for the separate signal region bins. The statistical uncertainty of the ${\text {e}\rightarrow \gamma } {}$ background is due to the limited size of the collected data sample. All other statistical uncertainties are due to the limited number of simulated events. The systematic uncertainties of the individual background components are added in quadrature.

Summary

We have searched for electroweak and strong production of gauginos in the framework of gauge mediated supersymmetry breaking in final states with photons and

$p_{\mathrm{T}}^{\text{miss}}$ . A dataset recorded at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb

$^{-1}$ , was analyzed. The data are found to agree with the SM expectation, without any indication of new physics.

The analysis is sensitive to electroweak production and to strong production especially with compressed mass spectra, that are characterized by photons,

$p_{\mathrm{T}}^{\text{miss}}$ and moderate hadronic activity in the final state. Two electroweak simplified models are used for the interpretation. The analysis excludes NLSP masses below 750 GeV at the 95% CL in the TChiWg scenario. Additionally, limits are set for four strong production simplified models based on gluino (T5gg, T5Wg) and squark (T6gg, T6Wg) pair-production. This result complements searches in the photon+jets, diphoton, and photon+leptons final states and sets the most stringent limits in the electroweak model and the compressed mass phase space in the strong production models.

Additional Figures
png pdf	Additional Figure 1: Sketch of the control region and signal region definition. The blue area indicates the phase space of the validation region.

Additional Tables
png pdf	Additional Table 1: Cutflow of the TChiWg benchmark signal point with a NLSP mass of 700 GeV. The preselection cut comprises the requirement of at least one loosely isolated photon with ${p_{\mathrm {T}}} >$ 180 GeV and a seed crystal energy fraction of at least 30% wrt. the full corrected photon ${p_{\mathrm {T}}}$ , which was accepted by the trigger and was measured in the ECAL barrel. Furthermore, for the photon a minimal distance in $\Delta R$ of 0.5 is required wrt. to the nearest jet. Also $\Delta \phi ( p_{\mathrm{T}}^{\text{miss}} , \text{jet} ) >$ 0.3 is required for all jets with ${p_{\mathrm {T}}} >$ 100 GeV. The FastSim strange jet veto is also included in the preselection cut.
png pdf	Additional Table 2: Cutflow of the T5Wg benchmark signal point with a gluino mass of 1750 GeV and a gaugino mass of 1700 GeV. The preselection cut comprises the requirement of at least one loosely isolated photon with ${p_{\mathrm {T}}} >$ 180 GeV and a seed crystal energy fraction of at least 30% wrt. the full corrected photon ${p_{\mathrm {T}}}$ , which was accepted by the trigger and was measured in the ECAL barrel. Furthermore, for the photon a minimal distance in $\Delta R$ of 0.5 is required wrt. to the nearest jet. Also $\Delta \phi ( p_{\mathrm{T}}^{\text{miss}} , \text{jet} ) >$ 0.3 is required for all jets with ${p_{\mathrm {T}}} >$ 100 GeV. The FastSim strange jet veto is also included in the preselection cut.

References
1	P. Ramond	Dual theory for free fermions	PRD 3 (1971) 2415
2	P. Ramond	An interpretation of dual theories	Nuovo Cim. A 4 (1971) 544
3	Y. A. Golfand and E. P. Likhtman	Extension of the algebra of Poincare group generators and violation of P invariance	JEPTL 13 (1971) 323
4	D. V. Volkov and V. P. Akulov	Possible universal neutrino interaction	JEPTL 16 (1972) 438
5	J. Wess and B. Zumino	Supergauge transformations in four-dimensions	Nucl. Phys. B 70 (1974) 39
6	D. Z. Freedman, P. van Nieuwenhuizen, and S. Ferrara	Progress toward a theory of supergravity	PRD 13 (1976) 3214
7	S. Deser and B. Zumino	Consistent supergravity	PLB 62 (1976) 335
8	D. Z. Freedman and P. van Nieuwenhuizen	Properties of supergravity theory	PRD 14 (1976) 912
9	S. Ferrara and P. van Nieuwenhuizen	Consistent supergravity with complex spin 3/2 gauge fields	PRL 37 (1976) 1669
10	P. Fayet	Supergauge invariant extension of the Higgs mechanism and a model for the electron and its neutrino	Nucl. Phys. B 90 (1975) 104
11	A. H. Chamseddine, R. L. Arnowitt, and P. Nath	Locally supersymmetric grand unification	PRL 49 (1982) 970
12	R. Barbieri, S. Ferrara, and C. A. Savoy	Gauge models with spontaneously broken local supersymmetry	PLB 119 (1982) 343
13	L. J. Hall, J. D. Lykken, and S. Weinberg	Supergravity as the messenger of supersymmetry breaking	PRD 27 (1983) 2359
14	G. L. Kane, C. F. Kolda, L. Roszkowski, and J. D. Wells	Study of constrained minimal supersymmetry	PRD 49 (1994) 6173	hep-ph/9312272
15	P. Fayet	Mixing between gravitational and weak interactions through the massive gravitino	PLB 70 (1977) 461
16	H. Baer, M. Brhlik, C. H. Chen, and X. Tata	Signals for the minimal gauge-mediated supersymmetry breaking model at the Fermilab Tevatron collider	PRD 55 (1997) 4463	hep-ph/9610358
17	H. Baer, P. G. Mercadante, X. Tata, and Y. L. Wang	Reach of Tevatron upgrades in gauge-mediated supersymmetry breaking models	PRD 60 (1999) 055001	hep-ph/9903333
18	S. Dimopoulos, S. Thomas, and J. D. Wells	Sparticle spectroscopy and electroweak symmetry breaking with gauge-mediated supersymmetry breaking	Nucl. Phys. B 488 (1997) 39	hep-ph/9609434
19	J. R. Ellis, J. L. Lopez, and D. V. Nanopoulos	Analysis of LEP constraints on supersymmetric models with a light gravitino	PLB 394 (1997) 354	hep-ph/9610470
20	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
21	G. F. Giudice and R. Rattazzi	Gauge-mediated supersymmetry breaking	in Perspectives on supersymmetry, p. 355 World Scientific, Singapore
22	R. Barbier et al.	R-parity violating supersymmetry	PR 420 (2005) 1	hep-ph/0406039
23	G. R. Farrar and P. Fayet	Phenomenology of the production, decay, and detection of new hadronic states associated with supersymmetry	PLB 76 (1978) 575
24	CMS Collaboration	Search for supersymmetry in electroweak production with photons and large missing transverse energy in pp collisions at $\sqrt{s} =$ 8 TeV	PLB759 (2016) 479--500	CMS-SUS-14-016 1602.08772
25	CMS Collaboration	Search for supersymmetry with a photon, a lepton, and missing transverse momentum in pp Collisions at $\sqrt{s} =$ 8 TeV		CMS-SUS-14-013 1508.01218
26	ATLAS Collaboration	Search for photonic signatures of gauge-mediated supersymmetry in 8 TeV pp collisions with the ATLAS detector	PRD 92 (2015) 072001	1507.05493
27	CMS Collaboration	Search for new physics in events with photons, jets, and missing transverse energy in pp collisions at $\sqrt{s} =$ 7 TeV	JHEP 03 (2013) 111	CMS-SUS-12-001 1211.4784
28	CMS Collaboration	Search for supersymmetry with photons in pp collisions at $\sqrt{s} =$ 8 TeV	PRD 92 (2015) 072006	CMS-SUS-14-004 1507.02898
29	CMS Collaboration	Interpretation of Searches for Supersymmetry with simplified Models	PRD88 (2013), no. 5, 052017	CMS-SUS-11-016 1301.2175
30	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
31	CMS Collaboration	The CMS experiment at the CERN LHC	JINST 3 (2008) S08004	CMS-00-001
32	CMS Collaboration	Particle--flow event reconstruction in CMS and performance for jets, taus, and $E_{\mathrm{T}}^{\text{miss}}$	CDS
33	CMS Collaboration	Commissioning of the particle-flow event reconstruction with the first LHC collisions recorded in the CMS detector	CDS
34	M. Cacciari, G. P. Salam, and G. Soyez	The anti- $k_t$ jet clustering algorithm	JHEP 04 (2008) 063	0802.1189
35	M. Cacciari, G. P. Salam, and G. Soyez	FastJet user manual	EPJC 72 (2012) 1896	1111.6097
36	M. Cacciari and G. P. Salam	Pileup subtraction using jet areas	PLB 659 (2008) 119	0707.1378
37	CMS Collaboration	Determination of jet energy calibration and transverse momentum resolution in CMS	JINST 6 (2011) 11002	CMS-JME-10-011 1107.4277
38	CMS Collaboration	Performance of the CMS missing transverse momentum reconstruction in pp data at $\sqrt{s} =$ 8 TeV	JINST 10 (2015) P02006	CMS-JME-13-003 1411.0511
39	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
40	P. Nason	A New method for combining NLO QCD with shower Monte Carlo algorithms	JHEP 11 (2004) 040	hep-ph/0409146
41	S. Frixione, P. Nason, and C. Oleari	Matching NLO QCD computations with Parton Shower simulations: the POWHEG method	JHEP 11 (2007) 070	0709.2092
42	S. Alioli, P. Nason, C. Oleari, and E. Re	A general framework for implementing NLO calculations in shower Monte Carlo programs: the POWHEG BOX	JHEP 06 (2010) 043	1002.2581
43	T. Melia, P. Nason, R. Rontsch, and G. Zanderighi	W+W-, WZ and ZZ production in the POWHEG BOX	JHEP 11 (2011) 078	1107.5051
44	P. Nason and G. Zanderighi	$W^+ W^-$ , $W Z$ and $Z Z$ production in the POWHEG-BOX-V2	EPJC 74 (2014), no. 1	1311.1365
45	T. Sjostrand, S. Mrenna, and P. Z. Skands	PYTHIA 6.4 physics and manual	JHEP 05 (2006) 026	hep-ph/0603175
46	G. Bozzi et al.	Production of Drell-Yan lepton pairs in hadron collisions: Transverse-momentum resummation at next-to-next-to-leading logarithmic accuracy	PLB696 (2011) 207--213	1007.2351
47	M. Kramer et al.	Supersymmetry production cross sections in $pp$ collisions at $\sqrt{s} =$ 7 TeV		1206.2892
48	NNPDF Collaboration	Parton distributions for the LHC Run II	JHEP 04 (2015) 040	1410.8849
49	GEANT4 Collaboration	GEANT4---a simulation toolkit	NIMA 506 (2003) 250
50	CMS Collaboration	CMS luminosity based on pixel cluster counting --- summer 2013 update	CMS-PAS-LUM-13-001	CMS-PAS-LUM-13-001
51	T. Junk	Confidence level computation for combining searches with small statistics	NIMA 434 (1999) 435	hep-ex/9902006
52	A. L. Read	Presentation of search results: the CLs technique	JPG 28 (2002) 2693
53	ATLAS, CMS, LHC Higgs Combination Group Collaborations	Procedure for the LHC Higgs boson search combination in Summer 2011	CMS-NOTE-2011-005
54	E. Gross and O. Vitells	Trial factors or the look elsewhere effect in high energy physics	EPJC 70 (2010) 525	1005.1891
55	CMS Collaboration Collaboration	Simplified likelihood for the re-interpretation of public CMS results	CMS-NOTE-2017-001