CMS logoCMS event Hgg
Compact Muon Solenoid
LHC, CERN

CMS-EXO-19-018 ; CERN-EP-2019-265
Search for a narrow resonance lighter than 200 GeV decaying to a pair of muons in proton-proton collisions at $\sqrt{s} = $ 13 TeV
Phys. Rev. Lett. 124 (2020) 131802
Abstract: A search is presented for a narrow resonance decaying to a pair of oppositely charged muons using $\sqrt{s} = $ 13 TeV proton-proton collision data recorded at the LHC. In the 45-75 and 110-200 GeV resonance mass ranges, the search is based on conventional triggering and event reconstruction techniques. In the 11.5-45 GeV mass range, the search uses data collected with dimuon triggers with low transverse momentum thresholds, recorded at high rate by storing a reduced amount of trigger-level information. The data correspond to integrated luminosities of 137 fb$^{-1}$ and 96.6 fb$^{-1}$ for conventional and high-rate triggering, respectively. No significant resonant peaks are observed in the probed mass ranges. The search sets the most stringent constraints to date on a dark photon in the $\sim$ 30-75 and 110-200 GeV mass ranges.
Figures Summary References CMS Publications
Figures

png pdf
Figure 1:
The $m_{\mu\mu}$ distributions of events selected with the standard muon triggers (maroon, darker), and the scouting dimuon triggers (green, lighter). Events are required to pass all the selection requirements. The inset is restricted to events in the barrel category in the mass range 23.9-26.1 GeV. A function describing the background is fit to these data, and a 25 GeV $\mathrm{Z} _{\mathrm {D}}$ signal corresponding to $\epsilon ^{2} = 2 \times 10^{-5}$ is added. The bottom panel of the inset shows the bin-by-bin difference between the number of events in data and the prediction from the background fit, divided by the statistical uncertainty.

png pdf
Figure 2:
Expected and observed upper limits at 95% CL on the product of the signal cross section ($\sigma $) for a narrow resonance, branching fraction to a pair of muons ($\mathcal {B}$), and acceptance (A) as a function of the mass of a narrow resonance. Results obtained using the scouting (standard) triggers are to the left (right) of the vertical purple line.

png pdf
Figure 3:
Expected and observed upper limits at 90% CL on $\epsilon ^{2}$, the square of the kinetic mixing coefficient, as a function of the $\mathrm{Z} _{\mathrm {D}}$ mass. Results obtained using the scouting (standard) triggers are to the left (right) of the vertical purple line. Limits at 90% CL from the search performed by the LHCb Collaboration [16] are shown in red, and constraints at 95% CL from the measurements of the electroweak observables are shown in light blue [9].
Summary
In summary, a search has been presented for a narrow resonance decaying to a pair of muons using proton-proton collision data recorded by the CMS experiment at $\sqrt{s}=$ 13 TeV. The search in the 45--75 and 110--200 GeV resonance mass ranges uses fully reconstructed data containing a pair of muons with transverse momenta greater than 20 and 10 GeV, corresponding to an integrated luminosity of 137 fb$^{-1}$. The search in the resonance mass range of 11.5--45.0 GeV is performed using data collected with high-rate dimuon triggers, corresponding to an integrated luminosity of 96.6 fb$^{-1}$. This is the first search that uses data with reduced trigger-level muon information, collected with dimuon triggers that have transverse momentum thresholds of 3 GeV. The data are found to be consistent with the background prediction. The search sets the lowest upper limits to date on the kinetic mixing coefficient of a dark photon in the $\sim$30--75 and 110--200 GeV mass ranges.
References
1 G. Bertone and J. Silk Particle dark matter: observations, models and searches ch. Particle dark matter Cambridge University Press, Cambridge
2 J. L. Feng Dark matter candidates from particle physics and methods of detection Ann. Rev. Astron. Astrophys. 48 (2010) 495 1003.0904
3 T. A. Porter, R. P. Johnson, and P. W. Graham Dark matter searches with astroparticle data Ann. Rev. Astron. Astrophys. 49 (2011) 155 1104.2836
4 Planck Collaboration Planck 2015 results. XIII. cosmological parameters Astron. Astrophys. 594 (2016) A13 1502.01589
5 R. Essig et al. Dark sectors and new, light weakly-coupled particles in Planning the Future of U.S. Particle Physics: The Snowmass 2013 Proceedings, R. H. Bernstein et al., eds Minneapolis, MN, USA, July-August 1311.0029
6 P. Galison and A. Manohar Two Z's or not two Z's? PLB 136 (1984) 279
7 B. Holdom Two U(1)'s and $ \epsilon $ charge shifts PLB 166 (1986) 196
8 K. R. Dienes, C. F. Kolda, and J. March-Russell Kinetic mixing and the supersymmetric gauge hierarchy NPB 492 (1997) 104 hep-ph/9610479
9 D. Curtin, R. Essig, S. Gori, and J. Shelton Illuminating dark photons with high-energy colliders JHEP 02 (2015) 157 1412.0018
10 A. Konaka et al. Search for neutral particles in electron-beam-dump experiment PRL 57 (1986) 659
11 APEX Collaboration Search for a new gauge boson in electron-nucleus fixed-target scattering by the APEX Experiment PRL 107 (2011) 191804 1108.2750
12 SINDRUM I Collaboration Search for weakly interacting neutral bosons produced in $ \pi^{-} $p interactions at rest and decaying into e$ ^{+} $e$ ^{-} $ pairs PRL 68 (1992) 3845
13 BaBar Collaboration Search for a dark photon in $ e^+e^- $ collisions at BaBar PRL 113 (2014) 201801 1406.2980
14 P. Ilten et al. Proposed inclusive dark photon search at LHCb PRL 116 (2016) 251803 1603.08926
15 LHCb Collaboration Search for dark photons produced in 13 $ TeV pp $ collisions PRL 120 (2018) 061801 1710.02867
16 LHCb Collaboration Search for $ A'\!\to\!\mu^+\mu^- $ decays Submitted to PRLett 1910.06926
17 CMS Collaboration The CMS experiment at the CERN LHC JINST 3 (2008) S08004 CMS-00-001
18 CMS Collaboration The CMS trigger system JINST 12 (2017) P01020 CMS-TRG-12-001
1609.02366
19 CMS Collaboration Search for narrow resonances in dijet final states at $ \sqrt{s}= $ 8 TeV with the novel CMS technique of data scouting PRL 117 (2016) 031802 CMS-EXO-14-005
1604.08907
20 S. Gopalakrishna, S. Jung, and J. D. Wells Higgs boson decays to four fermions through an Abelian hidden sector PRD 78 (2008) 055002 0801.3456
21 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
22 T. Sjostrand et al. An Introduction to PYTHIA 8.2 CPC 191 (2015) 159 1410.3012
23 CMS Collaboration Event generator tunes obtained from underlying event and multiparton scattering measurements EPJC 76 (2016) 155 CMS-GEN-14-001
1512.00815
24 CMS Collaboration Extraction and validation of a new set of CMS PYTHIA8 tunes from underlying-event measurements Submitted to EPJC CMS-GEN-17-001
1903.12179
25 M. L. Mangano, M. Moretti, F. Piccinini, and M. Treccani Matching matrix elements and shower evolution for top-quark production in hadronic collisions JHEP 01 (2007) 013 hep-ph/0611129
26 R. Frederix and S. Frixione Merging meets matching in MC@NLO JHEP 12 (2012) 061 1209.6215
27 NNPDF Collaboration Parton distributions for the LHC Run II JHEP 04 (2015) 040 1410.8849
28 NNPDF Collaboration Parton distributions from high-precision collider data EPJC 77 (2017) 663 1706.00428
29 GEANT4 Collaboration GEANT4--a simulation toolkit NIMA 506 (2003) 250
30 CMS Collaboration Particle-flow reconstruction and global event description with the CMS detector JINST 12 (2017) P10003 CMS-PRF-14-001
1706.04965
31 M. Cacciari, G. P. Salam, and G. Soyez The anti-$ {k_{\mathrm{T}}} $ jet clustering algorithm JHEP 04 (2008) 063 0802.1189
32 M. Cacciari, G. P. Salam, and G. Soyez FastJet user manual EPJC 72 (2012) 1896 1111.6097
33 CMS Collaboration Identification of heavy-flavour jets with the CMS detector in pp collisions at 13 TeV JINST 13 (2018) P05011 CMS-BTV-16-002
1712.07158
34 CMS Collaboration Performance of the CMS muon detector and muon reconstruction with proton-proton collisions at $ \sqrt{s}= $ 13 TeV JINST 13 (2018) P06015 CMS-MUO-16-001
1804.04528
35 J. E. Gaiser Charmonium Spectroscopy from Radiative Decays of the $ J/\psi $ and $ \psi' $ Ph.D. thesis, Stanford University. SLAC Report SLAC-R-255
36 CMS Collaboration CMS luminosity measurements for the 2016 data taking period CMS-PAS-LUM-17-001 CMS-PAS-LUM-17-001
37 CMS Collaboration CMS luminosity measurement for the 2017 data-taking period at $ \sqrt{s} = $ 13 TeV CMS-PAS-LUM-17-004 CMS-PAS-LUM-17-004
38 CMS Collaboration CMS luminosity measurement for the 2018 data-taking period at $ \sqrt{s} = $ 13 TeV CMS-PAS-LUM-18-002 CMS-PAS-LUM-18-002
39 CMS Collaboration Search for the Higgs boson decaying to two muons in proton-proton collisions at $ \sqrt{s} = $ 13 TeV PRL 122 (2019) 021801 CMS-HIG-17-019
1807.06325
40 A. L. Read Presentation of search results: The CL$ _{\text{s}} $ technique JPG 28 (2002) 2693
41 T. Junk Confidence level computation for combining searches with small statistics NIMA 434 (1999) 435 hep-ex/9902006
42 G. Cowan, K. Cranmer, E. Gross, and O. Vitells Asymptotic formulae for likelihood-based tests of new physics EPJC 71 (2011) 1554 1007.1727
43 P. Ilten, Y. Soreq, M. Williams, and W. Xue Serendipity in dark photon searches JHEP 06 (2018) 004 1801.04847
Compact Muon Solenoid
LHC, CERN