CMS-EXO-15-006 ; CERN-EP-2016-281 | ||
Search for heavy gauge W' bosons in events with an energetic lepton and large missing transverse momentum at $ \sqrt{s} = $ 13 TeV | ||
CMS Collaboration | ||
29 December 2016 | ||
Phys. Lett. B 770 (2017) 278 | ||
Abstract: A search is presented for W' bosons in events with an electron or muon and large missing transverse momentum, using proton-proton collision data at $ \sqrt{s} = $ 13 TeV collected with the CMS detector in 2015 and corresponding to an integrated luminosity of 2.3 fb$^{-1}$. No evidence of an excess of events relative to the standard model expectations is observed. For a W' boson described by the sequential standard model, upper limits at 95% confidence level are set on the product of the production cross section and branching fraction and lower limits are established on the new boson mass. Masses below 4.1 TeV are excluded combining electron and muon decay channels, significantly improving upon the results obtained with the 8 TeV data. Exclusion limits at 95% confidence level on the product of the W' production cross section and branching fraction are also derived in combination with the 8 TeV data. Finally, exclusion limits are set for the production of generic W' bosons decaying into this final state using a model-independent approach. | ||
Links: e-print arXiv:1612.09274 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; CADI line (restricted) ; |
Figures | |
png pdf |
Figure 1:
Production and decay of an SSM W' boson. The final state shown denotes both the ($\overline {\ell }\nu _{\ell }$) state and its charge conjugate. |
png pdf |
Figure 2:
Distributions for data and expected SM backgrounds in the electron channel: transverse mass ${M_\mathrm {T}}$ (left) and the associated integral distribution (total number of events above a given value of ${M_\mathrm {T}}$) (right). The expected signals from the decays of W' bosons with masses $M(W') = $ 2.4 and 3.6 TeV are also shown in the left figure. The lower panels show the ratio of data to SM predictions, where the band centered around unity indicates the systematic uncertainty in the expected background, excluding the 2.7% uncertainty in the luminosity. |
png pdf |
Figure 2-a:
Transverse mass ${M_\mathrm {T}}$ distribution for data and expected SM backgrounds in the electron channel. The expected signals from the decays of W' bosons with masses $M(W') = $ 2.4 and 3.6 TeV are also shown in the left figure. The lower panel shows the ratio of data to SM predictions, where the band centered around unity indicates the systematic uncertainty in the expected background, excluding the 2.7% uncertainty in the luminosity. |
png pdf |
Figure 2-b:
Integral distribution for data and expected SM backgrounds in the electron channel (total number of events above a given value of ${M_\mathrm {T}}$). The expected signals from the decays of W' bosons with masses $M(W') = $ 2.4 and 3.6 TeV are also shown in the left figure. The lower panel shows the ratio of data to SM predictions, where the band centered around unity indicates the systematic uncertainty in the expected background, excluding the 2.7% uncertainty in the luminosity. |
png pdf |
Figure 3:
Distributions for data and expected SM backgrounds in the muon channel: transverse mass ${M_\mathrm {T}}$ (left) and the associated integral distribution (total number of events above a given value of ${M_\mathrm {T}}$) (right). The expected signals from the decays of W' bosons with masses $M(W') = $ 2.4 and 3.6 TeV are also shown in the left figure. The lower panels show the ratio of data to SM predictions, where the band centered around unity indicates the systematic uncertainty in the expected background, excluding the 2.7% uncertainty in the luminosity. |
png pdf |
Figure 3-a:
Transverse mass ${M_\mathrm {T}}$ distribution for data and expected SM backgrounds in the muon channel. The expected signals from the decays of W' bosons with masses $M(W') = $ 2.4 and 3.6 TeV are also shown in the left figure. The lower panel shows the ratio of data to SM predictions, where the band centered around unity indicates the systematic uncertainty in the expected background, excluding the 2.7% uncertainty in the luminosity. |
png pdf |
Figure 3-b:
Integral distribution for data and expected SM backgrounds in the muon channel (total number of events above a given value of ${M_\mathrm {T}}$). The expected signals from the decays of W' bosons with masses $M(W') = $ 2.4 and 3.6 TeV are also shown in the left figure. The lower panel shows the ratio of data to SM predictions, where the band centered around unity indicates the systematic uncertainty in the expected background, excluding the 2.7% uncertainty in the luminosity. |
png pdf |
Figure 4:
Expected and observed 95% CL limits for the electron (left) and muon (right) decay channels. The expected (observed) limit is displayed as a dashed (solid) line and the associated inner (outer) bands represent the one (two) standard deviation (s.d.) uncertainties. The SSM W' NNLO cross sections are displayed as a function of $M(W')$. |
png pdf |
Figure 4-a:
Expected and observed 95% CL limits for the electron decay channel. The expected (observed) limit is displayed as a dashed (solid) line and the associated inner (outer) bands represent the one (two) standard deviation (s.d.) uncertainties. The SSM W' NNLO cross sections are displayed as a function of $M(W')$. |
png pdf |
Figure 4-b:
Expected and observed 95% CL limits for the muon decay channel. The expected (observed) limit is displayed as a dashed (solid) line and the associated inner (outer) bands represent the one (two) standard deviation (s.d.) uncertainties. The SSM W' NNLO cross sections are displayed as a function of $M(W')$. |
png pdf |
Figure 5:
Expected and observed 95% CL limits for the combination of the electron and muon decay channels. The expected (observed) limit is displayed as a dashed (solid) line and the associated inner (outer) bands represent the one (two) standard deviation (s.d.) uncertainties. The SSM W' NNLO cross section is displayed as a function of $M(W')$. |
png pdf |
Figure 6:
Ratio of the cross section lower limit to the theoretical cross section shown in red (lighter curves) for the 8 TeV data, blue (darker curves) for the 13 TeV data, and black for the combined data sets in the electron (left) and muon (right) channels. The observed limits are shown with solid lines and expected limits with dashed lines. For the W' mass range 400-4000 GeV, where the combination is limited by the 8 TeV data set, the one- and two-standard deviation (s.d.) uncertainty bands for the combined limits are shown in green and yellow, respectively. |
png pdf |
Figure 6-a:
Ratio of the cross section lower limit to the theoretical cross section shown in red (lighter curves) for the 8 TeV data, blue (darker curves) for the 13 TeV data, and black for the combined data sets in the electron channel. The observed limits are shown with solid lines and expected limits with dashed lines. For the W' mass range 400-4000 GeV, where the combination is limited by the 8 TeV data set, the one- and two-standard deviation (s.d.) uncertainty bands for the combined limits are shown in green and yellow, respectively. |
png pdf |
Figure 6-b:
Ratio of the cross section lower limit to the theoretical cross section shown in red (lighter curves) for the 8 TeV data, blue (darker curves) for the 13 TeV data, and black for the combined data sets in the muon channel. The observed limits are shown with solid lines and expected limits with dashed lines. For the W' mass range 400-4000 GeV, where the combination is limited by the 8 TeV data set, the one- and two-standard deviation (s.d.) uncertainty bands for the combined limits are shown in green and yellow, respectively. |
png pdf |
Figure 7:
Expected (dashed line) and observed (solid line) 95% CL limit for the model-independent cross section limit as a function of the lower ${M_\mathrm {T}}$ threshold, denoted ${M_\mathrm {T}^\mathrm {min}} $, for the electron channel (upper left), the muon channel (upper right), and the combined channels (bottom plot). The inner (outer) bands represent the one- (two-)standard deviation (s.d.) uncertainties. |
png pdf |
Figure 7-a:
Expected (dashed line) and observed (solid line) 95% CL limit for the model-independent cross section limit as a function of the lower ${M_\mathrm {T}}$ threshold, denoted ${M_\mathrm {T}^\mathrm {min}} $, for the electron channel. The inner (outer) bands represent the one- (two-)standard deviation (s.d.) uncertainties. |
png pdf |
Figure 7-b:
Expected (dashed line) and observed (solid line) 95% CL limit for the model-independent cross section limit as a function of the lower ${M_\mathrm {T}}$ threshold, denoted ${M_\mathrm {T}^\mathrm {min}} $, for the muon channel. The inner (outer) bands represent the one- (two-)standard deviation (s.d.) uncertainties. |
png pdf |
Figure 7-c:
Expected (dashed line) and observed (solid line) 95% CL limit for the model-independent cross section limit as a function of the lower ${M_\mathrm {T}}$ threshold, denoted ${M_\mathrm {T}^\mathrm {min}} $, for the combined channels. The inner (outer) bands represent the one- (two-)standard deviation (s.d.) uncertainties. |
Tables | |
png pdf |
Table 1:
Numbers of events in the electron decay channel integrated above ${M_\mathrm {T}}$ thresholds of 500, 1000, and 1500 GeV, for data, SM background, and signals with M$(W') =$ 2.4 and 3.6 TeV . The uncertainties include systematic and statistical uncertainties, but do not include the 2.7% uncertainty in the integrated luminosity. |
png pdf |
Table 2:
Numbers of events in the muon decay channel integrated above ${M_\mathrm {T}}$ thresholds of 500, 1000, and 1500 GeV, for data, SM background, and signals with M$(W')$ = 2.4 and 3.6 TeV . The uncertainties include statistical and systematic uncertainties, but do not include the 2.7% uncertainty in the integrated luminosity. |
Summary |
A search has been performed for sequential standard model W' bosons in final states containing a single energetic electron or muon and large missing transverse momentum, using proton-proton collision data at $ \sqrt{s} = $ 13 TeV, corresponding to an integrated luminosity of 2.3 fb$^{-1}$. No deviation from the background expectations has been observed and exclusion limits at 95% confidence level have been extracted on the mass of a W' boson. Masses below 3.6 (3.9) TeV are excluded in the electron (muon) decay channel analysis, significantly improving upon the results obtained with the $ \sqrt{s} = $ 8 TeV data. This search has been combined with the earlier one conducted at $8 TeV$, where the sensitivity of the search is dominated by the 13 TeV data, yielding a lower mass limit of 4.1 TeV for W' bosons when combining data from both decay channels and center-of-mass energies. Finally, generic limits on the production of W' resonances with the same leptonic final states have been obtained using a model-independent approach. |
References | ||||
1 | G. Altarelli, B. Mele, and M. Ruiz-Altaba | Searching for new heavy vector bosons in $ \mathrm{ p }\mathrm{\bar{p}} $ colliders | Z. Phys. C 45 (1989) 109 | |
2 | CMS Collaboration | Search for a $ W^\prime $ or Techni-$ \rho $ Decaying into $ WZ $ in $ pp $ Collisions at $ \sqrt{s}=$ 7 TeV | PRL 109 (2012) 141801 | CMS-EXO-11-041 1206.0433 |
3 | CMS Collaboration | Search for new resonances decaying via WZ to leptons in proton-proton collisions at $ \sqrt{s}=$ 8 TeV | PLB 740 (2015) 83 | CMS-EXO-12-025 1407.3476 |
4 | D0 Collaboration | Search for $ W' $ Bosons Decaying to an Electron and a Neutrino with the D0 Detector | PRL 100 (2008) 031804, ,%%CITATION = ARXIV:0710.2966%% | 0710.2966 |
5 | CDF Collaboration | Search for a New Heavy Gauge Boson $ W' $ with Electron + missing ET Event Signature in $ \mathrm{ p }\mathrm{\bar{p}} $ collisions at $ \sqrt{s} = $ 1.96 TeV | PRD 83 (2011) 031102 | 1012.5145 |
6 | CMS Collaboration | Search for physics beyond the standard model in final states with a lepton and missing transverse energy in proton-proton collisions at $ \sqrt{s}=$ 8 TeV | PRD 91 (2015) 092005 | CMS-EXO-12-060 1408.2745 |
7 | ATLAS Collaboration | Search for new particles in events with one lepton and missing transverse momentum in pp collisions at $ \sqrt{s}=$ 8 TeV with the ATLAS detector | JHEP 09 (2014) 037 | 1407.7494 |
8 | ATLAS Collaboration | Search for new resonances in events with one lepton and missing transverse momentum in pp collisions at $ \sqrt{s}=$ 13 TeV with the ATLAS detector | Submitted to PLB | 1606.03977 |
9 | CMS Collaboration | The CMS experiment at the CERN LHC | JINST 3 (2008) S08004 | CMS-00-001 |
10 | CMS Collaboration | The TriDAS Project Technical Design Report, volume I: The trigger systems | CMS TDR CERN/LHCC 2000-038, CERN | |
11 | CMS Collaboration | The TriDAS Project Technical Design Report, volume II: Data acquisition and high-level trigger | CDS | |
12 | 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 |
13 | T. Sj\"ostrand et al. | An introduction to PYTHIA 8.2 | Comp. Phys. Comm. 191 (2015) 159 | 1410.3012 |
14 | P. Skands, S. Carrazza, and J. Rojo | Tuning PYTHIA 8.1: the Monash 2013 Tune | EPJC 74 (2014) 3024 | 1404.5630 |
15 | CMS Collaboration | Event generator tunes obtained from underlying event and multiparton scattering measurements | EPJC 76 (2016) 155 | CMS-GEN-14-001 1512.00815 |
16 | NNPDF Collaboration | Parton distributions for the LHC Run II | JHEP 04 (2015) 040 | 1410.8849 |
17 | Y. Li and F. Petriello | Combining QCD and electroweak corrections to dilepton production in FEWZ | PRD 86 (2012) 094034 | 1208.5967 |
18 | S. G. Bondarenko and A. A. Sapronov | NLO EW and QCD proton-proton cross section calculations with mcsanc-v1.01 | Comp. Phys. Comm. 184 (2013) 2343 | 1301.3687 |
19 | L. Barze et al. | Neutral current Drell--Yan with combined QCD and electroweak corrections in the POWHEG BOX | EPJC 73 (2013) 2474 | 1302.4606 |
20 | S. Alioli, P. Nason, C. Oleari, and E. Re | Powheg (v2): A general framework for implementing NLO calculations in shower Monte Carlo programs: the POWHEG BOX | JHEP 06 (2010) 043 | 1002.2581 |
21 | S. Alioli, P. Nason, C. Oleari, and E. Re | NLO single-top production matched with shower in POWHEG: $ s $- and $ t $-channel contributions | JHEP 09 (2009) 111 | 0907.4076 |
22 | E. Re | Single-top $ Wt $-channel production matched with parton showers using the POWHEG method | EPJC 71 (2011) 1547 | 1009.2450 |
23 | J. M. Campbell, R. K. Ellis, P. Nason, and E. Re | Top-pair production and decay at NLO matched with parton showers | JHEP 04 (2015) 114 | 1412.1828 |
24 | R. Frederix and S. Frixione | Merging meets matching in MC@NLO | JHEP 12 (2012) 061 | 1209.6215 |
25 | R. D. Ball et al. | Parton distributions with LHC data | Nucl. Phys. B 867 (2013) 244 | 1207.1303 |
26 | GEANT4 Collaboration | GEANT4---a simulation toolkit | NIMA 506 (2003) 250 | |
27 | CMS Collaboration | Particle--flow event reconstruction in CMS and performance for jets, taus, and $ E_{\mathrm{T}}^{\text{miss}} $ | CDS | |
28 | CMS Collaboration | Commissioning of the particle-flow event reconstruction with the first LHC collisions recorded in the CMS detector | CDS | |
29 | CMS Collaboration | Performance of missing energy reconstruction in 13 TeV pp collision data using the CMS detector | CMS-PAS-JME-16-004 | CMS-PAS-JME-16-004 |
30 | 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 |
31 | CMS Collaboration | Search for physics beyond the standard model in dilepton mass spectra in proton-proton collisions at $ \sqrt{s}=$ 8 TeV | JHEP 04 (2015) 025 | CMS-EXO-12-061 1412.6302 |
32 | CMS Collaboration | Search for narrow resonances in dilepton mass spectra in proton-proton collisions at $ \sqrt{s}=$ 13 TeV and combination with $ \sqrt{s}=$ 8 TeV data | Submitted to PLB | CMS-EXO-15-005 1609.05391 |
33 | CMS Collaboration | Performance of CMS muon reconstruction in pp collision events at $ \sqrt{s}=$ 7 TeV | JINST 7 (2012) P10002 | CMS-MUO-10-004 1206.4071 |
34 | CMS Collaboration | The performance of CMS muon detector in proton-proton collision at $ \sqrt{s}=$ 7 TeV at the LHC | JINST 8 (2013) P11002 | CMS-MUO-11-001 1306.6905 |
35 | CMS Collaboration | CMS luminosity measurement for the 2015 data taking period | CMS-PAS-LUM-15-001 | CMS-PAS-LUM-15-001 |
36 | J. Butterworth et al. | PDF4LHC recommendations for LHC Run II | JPG 43 (2016) 023001 | 1510.03865 |
37 | A. L. Read | Presentation of search results: the CL$ _\mathrm{s} $ technique | JPG 28 (2002) 2693 | |
38 | T. Junk | Confidence level computation for combining searches with small statistics | NIMA 434 (1999) 435 | |
39 | ATLAS and CMS Collaborations and LHC Higgs Combination Group | Procedure for the LHC Higgs boson search combination in summer 2011 | Technical Report ATL-PHYS-PUB-2011-011, CMS NOTE 2011/005 |
Compact Muon Solenoid LHC, CERN |