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CMS-PAS-EXO-16-039
Search for dark matter and graviton produced in association with a photon in pp collisions at $ \sqrt{s} = $ 13 TeV with an integrated luminosity of 12.9 fb$^{-1}$
Abstract: A search is conducted for dark matter pair-production and for graviton production predicted by the ADD large extra dimensions model in a final state with a photon and missing transverse energy in pp collisions at $\sqrt{s}=$ 13 TeV. Data taken by the CMS experiment in 2016 corresponding to an integrated luminosity of 12.9 fb$^{-1}$ is analyzed. A Poisson counting technique is used to assess a potential excess of events with respect to background, estimated through simulation and data-driven methods. No such excess is observed. The results of the searches are interpreted as exclusion limits in the model parameter spaces.
Figures & Tables Summary References CMS Publications
Figures

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Figure 1:
Example diagrams of new-physics interactions that lead to a final state of $ {\gamma }$ and large missing transverse momentum.

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Figure 1-a:
Example diagram of new-physics interactions that lead to a final state of $ {\gamma }$ and large missing transverse momentum.

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Figure 1-b:
Example diagram of new-physics interactions that lead to a final state of $ {\gamma }$ and large missing transverse momentum.

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Figure 1-c:
Example diagram of new-physics interactions that lead to a final state of $ {\gamma }$ and large missing transverse momentum.

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Figure 2:
The ${p_{\mathrm {T}}^{ {\gamma }}}$ and ${E_{\mathrm {T}}}^{\text{miss}} $ distributions for the candidate sample, compared with estimated contributions from SM backgrounds. Systematic and statistical uncertainties on the background estimates are added in quadrature.

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Figure 2-a:
The ${p_{\mathrm {T}}^{ {\gamma }}}$ distribution for the candidate sample, compared with estimated contributions from SM backgrounds. Systematic and statistical uncertainties on the background estimates are added in quadrature.

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Figure 2-b:
The ${E_{\mathrm {T}}}^{\text{miss}} $ distributions for the candidate sample, compared with estimated contributions from SM backgrounds. Systematic and statistical uncertainties on the background estimates are added in quadrature.

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Figure 3:
95% CL upper limits on $\mu = \sigma $/$\sigma _{\text {Theory}}$ in the ${M_{\text {med}}}- {m_{\text {DM}}}$ plane for vector and axial-vector mediator, assuming $g_{ {\mathrm {q}}}=$ 0.25 and $g_{\chi }=$ 1. Expected and observed exclusion contours are overlaid, where mass points to the lower left of the curves are excluded.

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Figure 3-a:
95% CL upper limits on $\mu = \sigma $/$\sigma _{\text {Theory}}$ in the ${M_{\text {med}}}- {m_{\text {DM}}}$ plane for a vector mediator, assuming $g_{ {\mathrm {q}}}=$ 0.25 and $g_{\chi }=$ 1. Expected and observed exclusion contours are overlaid, where mass points to the lower left of the curves are excluded.

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Figure 3-b:
95% CL upper limits on $\mu = \sigma $/$\sigma _{\text {Theory}}$ in the ${M_{\text {med}}}- {m_{\text {DM}}}$ plane for an axial-vector mediator, assuming $g_{ {\mathrm {q}}}=$ 0.25 and $g_{\chi }=$ 1. Expected and observed exclusion contours are overlaid, where mass points to the lower left of the curves are excluded.

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Figure 4:
The 90% CL exclusion limits on the $\chi $-nucleon scattering cross section in a simplified model of dark matter production involving a vector and axial-vector operator as a function of the ${m_{\text {DM}}}$. The region to the upper left of the contour is excluded. Shown together are corresponding exclusion contours, where regions above the curves are excluded, from the recent results by CDMSLite [27], LUX [28], PandaX [29], CRESST-II [30], PICO-2L [31], PICO-60 [32], IceCube [33], and SuperKamiokande [34] collaborations.

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Figure 4-a:
The 90% CL exclusion limits on the $\chi $-nucleon scattering cross section in a simplified model of dark matter production involving a vector operator as a function of the ${m_{\text {DM}}}$. The region to the upper left of the contour is excluded. Shown together are corresponding exclusion contours, where regions above the curves are excluded, from the recent results by CDMSLite [27], LUX [28], PandaX [29], CRESST-II [30], PICO-2L [31], PICO-60 [32], IceCube [33], and SuperKamiokande [34] collaborations.

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Figure 4-b:
The 90% CL exclusion limits on the $\chi $-nucleon scattering cross section in a simplified model of dark matter production involving an axial-vector operator as a function of the ${m_{\text {DM}}}$. The region to the upper left of the contour is excluded. Shown together are corresponding exclusion contours, where regions above the curves are excluded, from the recent results by CDMSLite [27], LUX [28], PandaX [29], CRESST-II [30], PICO-2L [31], PICO-60 [32], IceCube [33], and SuperKamiokande [34] collaborations.

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Figure 5:
The 95% CL expected and observed lower limits on $\Lambda $ for a dimension-7 operator EFT model with a contact interaction of type $\gamma \gamma \chi \overline {\chi }$ as a function of dark matter mass ${m_{\text {DM}}}$.

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Figure 6:
The 95% CL upper limits on the ADD graviton production cross sections as a function of ${M_D}$ for $n=3$.

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Figure 7:
Lower limit on ${M_D}$ as a function of $n$.
Tables

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Table 1:
Summary of estimated backgrounds and observed total number of candidates. Systematic and statistical uncertainties on the background estimates are added in quadrature.

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Table 2:
Summary of relative systematic uncertainties (%) for different background estimates.

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Table 3:
95% CL observed and expected lower limits on ${M_D}$ as a function of $n$.
Summary
Proton-proton collision events containing a photon and missing transverse momentum have been investigated to search for new phenomena. In the $ \sqrt{s} = $ 13 TeV data set corresponding to 12.9 fb$^{-1}$ of integrated luminosity, no deviations from the standard model predictions are observed. Upper limits are obtained on dark matter and ADD graviton production cross sections at 95% confidence level, which are then translated to limits on relevant parameters of the individual models. For the simplified dark matter production models considered, the search excludes mediator masses of up to 760 GeV for massless dark matter. For an effective dimension-7 photon-dark matter contact interaction, values of the suppression scale up to 620 GeV are excluded. For ADD extra dimensions, gravitational energy scale up to 2.44-2.60 TeV, depending on the number of extra dimensions, are excluded.
References
1 R. Gaitskell Direct Detection of Dark Matter Annual Review of Nuclear and Particle Science 54 (2004)
2 N. Arkani-Hamed, S. Dimopoulos, and G. Dvali The Hierarchy problem and new dimensions at a millimeter PLB 429 (1998) 263 hep-ph/9803315
3 A. Nelson et al. Confronting the Fermi Line with LHC data: an Effective Theory of Dark Matter Interaction with Photons PRD89 (2014), no. 5, 056011 1307.5064
4 D. Abercrombie et al. Dark Matter Benchmark Models for Early LHC Run-2 Searches: Report of the ATLAS/CMS Dark Matter Forum 1507.00966
5 CMS Collaboration Search for Dark Matter and Large Extra Dimensions in the gamma + MET final state in pp Collisions at sqrt(s) = 13 TeV
6 ATLAS Collaboration Search for new phenomena in events with a photon and missing transverse momentum in $ pp $ collisions at $ \sqrt{s}=13 $ TeV with the ATLAS detector JHEP 06 (2016) 059 1604.01306
7 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
8 CMS Collaboration The CMS experiment at the CERN LHC JINST 3 (2008) S08004 CMS-00-001
9 CMS Collaboration Particle-Flow Event Reconstruction in CMS and Performance for Jets, Taus, and MET CDS
10 CMS Collaboration Commissioning of the Particle-Flow Reconstruction in Minimum-Bias and Jet Events from pp Collisions at 7 TeV CDS
11 CMS Collaboration Performance of Photon Reconstruction and Identification with the CMS Detector in Proton-Proton Collisions at sqrt(s) = 8 TeV JINST 10 (2015), no. 08, P08010 CMS-EGM-14-001
1502.02702
12 M. Cacciari, G. P. Salam, and G. Soyez The anti-k$ _{\text{t}} $ jet clustering algorithm JHEP 04 (2008) 063 0802.1189
13 CMS Collaboration Performance of the CMS missing transverse momentum reconstruction in pp data at $ \sqrt{s} $ = 8 TeV JINST 10 (2015), no. 02, P02006 CMS-JME-13-003
1411.0511
14 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
15 T. Sj\"ostrand et al. An Introduction to PYTHIA 8.2 CPC 191 (2015) 159--177 1410.3012
16 GEANT4 Collaboration GEANT4--a simulation toolkit Nucl. Instrum. Meth A 506 (2003) 250
17 J. Allison et al. Geant4 Developments and Applications IEEE Trans. Nucl. Sci 53 (2006) 270
18 S. Catani, D. de Florian, G. Ferrera, and M. Grazzini Vector boson production at hadron colliders: transverse-momentum resummation and leptonic decay JHEP 12 (2015) 047 1507.06937
19 A. Denner, S. Dittmaier, M. Hecht, and C. Pasold NLO QCD and electroweak corrections to W+$ \gamma $ production with leptonic W-boson decays JHEP 04 (2015) 018 1412.7421
20 A. Denner, S. Dittmaier, M. Hecht, and C. Pasold NLO QCD and electroweak corrections to Z$ +\gamma $ production with leptonic Z-boson decays JHEP 02 (2016) 057 1510.08742
21 CMS Collaboration Isolated Photon Reconstruction and Identification at $ \sqrt{s}=7 $~TeV CDS
22 CMS Collaboration Measurements of Inclusive $ W $ and $ Z $ Cross Sections in $ pp $ Collisions at $ \sqrt{s}=7 $ TeV JHEP 01 (2011) 080 CMS-EWK-10-002
1012.2466
23 T. Junk Confidence level computation for combining searches with small statistics NIMA434 (1999) 435--443 hep-ex/9902006
24 A. L. Read Presentation of search results: The CL(s) technique JPG28 (2002) 2693--2704, .[,11(2002)]
25 ATLAS and CMS Collaborations, The LHC Higgs Combination Group Procedure for the LHC Higgs boson search combination in Summer 2011 CMS-NOTE-2011-005
26 G. Busoni et al. Recommendations on presenting LHC searches for missing transverse energy signals using simplified $ s $-channel models of dark matter 1603.04156
27 SuperCDMS Collaboration New Results from the Search for Low-Mass Weakly Interacting Massive Particles with the CDMS Low Ionization Threshold Experiment PRL 116 (2016), no. 7, 071301 1509.02448
28 LUX Collaboration Improved Limits on Scattering of Weakly Interacting Massive Particles from Reanalysis of 2013 LUX Data PRL 116 (2016), no. 16, 161301 1512.03506
29 PandaX-II Collaboration Dark Matter Results from First 98.7-day Data of PandaX-II Experiment 1607.07400
30 CRESST Collaboration Results on light dark matter particles with a low-threshold CRESST-II detector EPJC76 (2016), no. 1, 25 1509.01515
31 PICO Collaboration Improved dark matter search results from PICO-2L Run 2 PRD93 (2016), no. 6, 061101 1601.03729
32 PICO Collaboration Dark matter search results from the PICO-60 CF$ _3 $I bubble chamber PRD93 (2016), no. 5, 052014 1510.07754
33 IceCube Collaboration Improved limits on dark matter annihilation in the Sun with the 79-string IceCube detector and implications for supersymmetry JCAP 1604 (2016), no. 04, 022 1601.00653
34 Super-Kamiokande Collaboration Search for neutrinos from annihilation of captured low-mass dark matter particles in the Sun by Super-Kamiokande PRL 114 (2015), no. 14, 141301 1503.04858
35 CMS Collaboration Search for new phenomena in monophoton final states in proton-proton collisions at $ \sqrt s = $ 8 TeV PLB755 (2016) 102--124 CMS-EXO-12-047
1410.8812
36 G. F. Giudice, R. Rattazzi, and J. D. Wells Quantum gravity and extra dimensions at high-energy colliders Nucl. Phys. B544 (1999) 3--38 hep-ph/9811291
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