CMS-PAS-EXO-16-008 | ||
Search for new physics with high-mass $\tau$ lepton pairs in pp collisions at $\sqrt{s}$ = 13 TeV with the CMS detector | ||
CMS Collaboration | ||
June 2016 | ||
Abstract: A search for physics beyond the standard model in events containing $\tau$ lepton pairs of high mass is performed using proton-proton collisions at $\sqrt{s}$ = 13 TeV. The data were collected with the CMS detector at the LHC and correspond to an integrated luminosity of 2.2 fb$^{-1}$. The observation is in good agreement with the standard model prediction. An upper limit at 95% CL on the product of cross section times branching fraction into $\tau$ lepton pairs is calculated as a function of the resonance mass for the Sequential Standard Model. In this model, the presence of $Z'$ bosons decaying into $\tau$ lepton pairs is excluded for $Z'$ masses below 2.1 TeV. | ||
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These preliminary results are superseded in this paper, JHEP 02 (2017) 048. The superseded preliminary plots can be found here. |
Figures | |
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Figure 1-a:
$m(\tau _{1},\tau _{2}$, ${E_{\mathrm {T}}} )$ distribution for all four final states: (a) ${\tau _\mu \tau _{\textrm {h}}} $, (b) ${\tau _e\tau _{\textrm {h}}} $, (c) ${\tau _e\tau _\mu } $, and (d) ${\tau _{\textrm {h}}\tau _{\textrm {h}}} $. The dashed line represents the mass distribution for a $Z'_{SSM} \rightarrow \tau \tau $ with mass of 1500 GeV , in which the event yield is scaled by a factor 10. The rightmost bin includes events with a reconstructed mass greater than 900 GeV. |
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Figure 1-b:
$m(\tau _{1},\tau _{2}$, ${E_{\mathrm {T}}} )$ distribution for all four final states: (a) ${\tau _\mu \tau _{\textrm {h}}} $, (b) ${\tau _e\tau _{\textrm {h}}} $, (c) ${\tau _e\tau _\mu } $, and (d) ${\tau _{\textrm {h}}\tau _{\textrm {h}}} $. The dashed line represents the mass distribution for a $Z'_{SSM} \rightarrow \tau \tau $ with mass of 1500 GeV , in which the event yield is scaled by a factor 10. The rightmost bin includes events with a reconstructed mass greater than 900 GeV. |
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Figure 1-c:
$m(\tau _{1},\tau _{2}$, ${E_{\mathrm {T}}} )$ distribution for all four final states: (a) ${\tau _\mu \tau _{\textrm {h}}} $, (b) ${\tau _e\tau _{\textrm {h}}} $, (c) ${\tau _e\tau _\mu } $, and (d) ${\tau _{\textrm {h}}\tau _{\textrm {h}}} $. The dashed line represents the mass distribution for a $Z'_{SSM} \rightarrow \tau \tau $ with mass of 1500 GeV , in which the event yield is scaled by a factor 10. The rightmost bin includes events with a reconstructed mass greater than 900 GeV. |
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Figure 1-d:
$m(\tau _{1},\tau _{2}$, ${E_{\mathrm {T}}} )$ distribution for all four final states: (a) ${\tau _\mu \tau _{\textrm {h}}} $, (b) ${\tau _e\tau _{\textrm {h}}} $, (c) ${\tau _e\tau _\mu } $, and (d) ${\tau _{\textrm {h}}\tau _{\textrm {h}}} $. The dashed line represents the mass distribution for a $Z'_{SSM} \rightarrow \tau \tau $ with mass of 1500 GeV , in which the event yield is scaled by a factor 10. The rightmost bin includes events with a reconstructed mass greater than 900 GeV. |
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Figure 2-a:
95% CL upper limits on the product of the cross section times branching fraction into $\tau $ lepton pairs as a function of $Z'_{SSM}$ mass for (a) ${\tau _\mu \tau _{\textrm {h}}} $, (b) ${\tau _e\tau _{\textrm {h}}} $, (c) ${\tau _e\tau _\mu } $, (d) ${\tau _{\textrm {h}}\tau _{\textrm {h}}}$ final states, and (e) their combined 95% CL upper limits. |
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Figure 2-b:
95% CL upper limits on the product of the cross section times branching fraction into $\tau $ lepton pairs as a function of $Z'_{SSM}$ mass for (a) ${\tau _\mu \tau _{\textrm {h}}} $, (b) ${\tau _e\tau _{\textrm {h}}} $, (c) ${\tau _e\tau _\mu } $, (d) ${\tau _{\textrm {h}}\tau _{\textrm {h}}}$ final states, and (e) their combined 95% CL upper limits. |
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Figure 2-c:
95% CL upper limits on the product of the cross section times branching fraction into $\tau $ lepton pairs as a function of $Z'_{SSM}$ mass for (a) ${\tau _\mu \tau _{\textrm {h}}} $, (b) ${\tau _e\tau _{\textrm {h}}} $, (c) ${\tau _e\tau _\mu } $, (d) ${\tau _{\textrm {h}}\tau _{\textrm {h}}}$ final states, and (e) their combined 95% CL upper limits. |
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Figure 2-d:
95% CL upper limits on the product of the cross section times branching fraction into $\tau $ lepton pairs as a function of $Z'_{SSM}$ mass for (a) ${\tau _\mu \tau _{\textrm {h}}} $, (b) ${\tau _e\tau _{\textrm {h}}} $, (c) ${\tau _e\tau _\mu } $, (d) ${\tau _{\textrm {h}}\tau _{\textrm {h}}}$ final states, and (e) their combined 95% CL upper limits. |
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Figure 2-e:
95% CL upper limits on the product of the cross section times branching fraction into $\tau $ lepton pairs as a function of $Z'_{SSM}$ mass for (a) ${\tau _\mu \tau _{\textrm {h}}} $, (b) ${\tau _e\tau _{\textrm {h}}} $, (c) ${\tau _e\tau _\mu } $, (d) ${\tau _{\textrm {h}}\tau _{\textrm {h}}}$ final states, and (e) their combined 95% CL upper limits. |
Tables | |
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Table 1:
Number of events observed in data compared to expected background yields and hypothetical $Z^{'}_{SSM}$ signals of mass 1.0, 1.5, and 2.0 TeV . The expected signal yields are computed at NLO accuracy, using a k-factor of 1.3. The top table gives inclusive yields; the bottom table gives yields requiring $m(\tau _{1},\tau _{2}, {E_{\mathrm {T}}} ) > $ 300 GeV. The uncertainties quoted on the background yields represent the combined statistical and systematic uncertainties. |
Summary |
A search for new physics beyond the standard model in events containing $\tau$ lepton pairs of high mass has been performed, using data corresponding to an integrated luminosity of 2.2 fb$^{-1}$ collected by the CMS detector in pp collisions at $\sqrt{s} = 13 TeV$. The observed mass spectra in the ${\tau_\mu\tau_{\textrm{h}}} $, ${\tau_e\tau_{\textrm{h}}} $, $\tau_h \tau_h$, and ${\tau_e\tau_\mu}$ channels are consistent with the SM expectations and an upper limit at 95% CL on the product of cross section times branching fraction into $\tau$ lepton pairs has been determined as a function of the $Z'$ mass. The presence of $Z'$ bosons decaying to $\tau$ leptons is excluded by the data for $Z'$ masses below 2.1 TeV in the SSM. |
References | ||||
1 | P. Langacker | The Physics of Heavy Z-prime Gauge Bosons | Rev. Mod. Phys 81 (2009) p.1199--1228 | 0801.1345 |
2 | K. R. Lynch et al. | Finding $ Z' $ bosons coupled preferentially to the third family at LEP and the Tevatron | PRD 63 (2001) 035006 | hep-ph/0007286 |
3 | M. Cvetic and S. Godfrey | Discovery and Identification of Extra Gauge Bosons | Summary of the Working Subgroup on Extra Gauge Bosons of the DPF long-range planning study, OCIP/C-95-2 UPR-648-T | hep-ph/9504216 |
4 | ATLAS Collaboration | A search for high-mass resonances decaying to $ \tau^+ \tau^- $ in pp collisions at $ \sqrt{s} $ = 7 TeV with the ATLAS detector | PLB 719 (2013) 242--260 | 1210.6604 |
5 | ATLAS Collaboration | A search for high-mass resonances decaying to $ \tau^+ \tau^- $ in pp collisions at $ \sqrt{s} $ = 8 TeV with the ATLAS detector | JHEP 07 (2015) 157 | 1502.07177v2 |
6 | CMS Collaboration | Search for high mass resonances decaying into $ \tau $-lepton pairs in pp collisions at $ \sqrt{s} $ = 7 TeV with the CMS detector | PLB 716 (2012) 82--102 | CMS-EXO-11-031 1206.1725 |
7 | CMS Collaboration | Search for high-mass resonances and large extra dimensions with tau-lepton pairs decaying into final states with an electron and a muon at $ \sqrt{s} $ = 8 TeV | CDS | |
8 | ATLAS Collaboration | Search for new phenomena in the dilepton final state using proton-proton collisions at $ \sqrt{s} $ = 13 TeV with the ATLAS detector | ATLAS Notes ATLAS-CONF-2015-070 | |
9 | CMS Collaboration | Search for a Narrow Resonance Produced in 13 TeV pp Collisions Decaying to Electron Pair or Muon Pair Final States | CDS | |
10 | CMS Collaboration | The CMS experiment at the CERN LHC | JINST 3 (2008) S08004 | CMS-00-001 |
11 | CMS Collaboration | The CMS high level trigger | EPJC 46 (2006) 605 | |
12 | CMS Collaboration | Particle-Flow Event Reconstruction in CMS and Performance for Jets, Taus, and MET | CDS | |
13 | CMS Collaboration | Muon Reconstruction and Identification Improvements for Run-2 and First Results with 2015 Run Data | CMS Detector Performance Summary CMS-DP-15-015 | |
14 | CMS Collaboration | Performance of Electron Reconstruction and Selection with the CMS Detector in Proton-Proton Collisions at $ \sqrt{s} $ = 8 TeV | JINST 10 (2015) P06005 | CMS-EGM-13-001 1502.02701 |
15 | CMS Collaboration | Reconstruction and identification of tau lepton decays to hadrons and tau neutrino at CMS | JINST 11 (2016) P01019 | CMS-TAU-14-001 1510.07488 |
16 | M. Cacciari, G. P. Salam, and G. Soyez | FastJet user manual | CERN--PH--TH (2011) 297 | 1111.6097 |
17 | M. Cacciari and G. P. Salam | Dispelling the $ N^3 $ myth for the $ k_t $ jet-finder | PLB 641 (2006) 57--61 | hep-ph/0512210 |
18 | CMS Collaboration | Identification of b-quark jets with the CMS experiment | JINST 8 (2013) P04013 | CMS-BTV-12-001 1211.4462 |
19 | CMS Collaboration | Performance of Missing Transverse Momentum Reconstruction Algorithms in Proton-Proton Collisions at $ \sqrt{s} $ = 8 TeV with the CMS Detector | ||
20 | P. Skands, S. Carrazza, and J. Rojo | Tuning PYTHIA 8.1: the Monash 2013 Tune | Eur. Phys. J.C. 74 (2014) 057 | 1404.5630v1 |
21 | Z. Was et al. | TAUOLA the library for tau lepton decay | Nucl.Phys.Proc.Suppl. 98 (2001) 96--102 | hep-ph/0011305 |
22 | J. Alwall et al. | MadGraph 5 : Going Beyond | JHEP 1106 (2011) 128 | 1106.0522 |
23 | GEANT4 Collaboration | Geant4-a simulation toolkit | NIMA 506 (2003) 250 | |
24 | CDF Collaboration | Search for neutral MSSM Higgs bosons decaying to tau pairs in p-pbar collisions at $ \sqrt{s} $=1.96 TeV | PRL 96 (2006) 011802 | hep-ex/0508051 |
25 | CMS Collaboration | CMS Luminosity Measurement for the 2015 Data Taking Period | ||
26 | P. M. Nadolsky et al. | Implications of CTEQ global analysis for collider observables | PRD 78 (2008) 013004 | 0802.0007 |
27 | G. Nanava and Z. Was | How to use SANC to improve the PHOTOS Monte Carlo simulation of bremsstrahlung in leptonic W-Boson decays | Acta Phys.Polon. B 34 (2003) 4561--4570 | hep-ph/0303260 |
28 | G. Miu and T. Sjiostrand | W Production in an Improved Parton-Shower Approach | Phys.Lett. B 449 (1999) 313--320 | hep-ph/9812455 |
29 | T. Junk | Confidence level computation for combining searches with small statistics | NIMA 434 (1999) 435 | hep-ex/9902006 |
30 | A. Read | Modified frequentist analysis of search results (the $ {CL}_s $ method) | Technical Report CERN-OPEN-2000-005, CERN | |
31 | ATLAS and CMS Collaborations, LHC Higgs Combination Group | Procedure for the LHC Higgs boson search combination in Summer 2011 | ATL-PHYS-PUB/CMS NOTE 2011-11, 2011/005 |
Compact Muon Solenoid LHC, CERN |