CMS-EXO-17-008

CMS-EXO-17-008 ; CERN-EP-2018-202
Search for a W' boson decaying to a $\tau$ lepton and a neutrino in proton-proton collisions at $\sqrt{s} = $ 13 TeV
CMS Collaboration
31 July 2018
Phys. Lett. B 792 (2019) 107
Abstract: A search for a new high-mass resonance decaying to a tau lepton and a neutrino is reported. The analysis uses proton-proton collision data collected by the CMS experiment at the LHC at $\sqrt{s} = $ 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The search utilizes hadronically decaying tau leptons. No excess in the event yield is observed at high transverse masses of the $\tau$ and missing transverse momentum. An interpretation of results within the sequential standard model excludes W' boson masses below 4.0 TeV at 95% confidence level. Existing limits are also improved on models in which the W' boson decays preferentially to fermions of the third generation. Heavy W' bosons with masses less than 1.7-3.9 TeV, depending on the coupling in the non-universal G(221) model, are excluded at 95% confidence level. These are the most stringent limits on this model to date.
Links: e-print arXiv:1807.11421 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; CADI line (restricted) ;

Figures & Tables	Summary	References	CMS Publications

Figures
png pdf	Figure 1: Leading order Feynman diagram of the expected signal process $ {\mathrm {W}'} \to {\tau} {\nu}$.
png pdf	Figure 2: Branching fractions $\mathcal {B}({\mathrm {W}'})$ as a function of the mixing angle $\cot\theta _{\mathrm {E}}$, for W' boson decays in the NUGIM G(221) framework, as calculated in Refs. [2,21,22]. For $\cot\theta _{\mathrm {E}} = $ 1 the values correspond to those in the SSM, rescaled to accommodate the WH decay channel.
png pdf	Figure 3: (Left) The $ {m_{\mathrm {T}}} $ distribution after the final selection. The black symbols with error bars show data, while the filled histograms represent the SM backgrounds. Signal examples for SSM W' bosons with masses of 0.6, 1.0, 4.0, and 5.0 TeV are shown with the open histograms. (Right) The integral transverse mass distribution, where the value in each bin is equal to the number of events with transverse mass equal to or greater than the left of the bin. The lower panels show the ratio of data to prediction, and the gray band represents the systematic uncertainties.
png pdf	Figure 3-a: The $ {m_{\mathrm {T}}} $ distribution after the final selection. The black symbols with error bars show data, while the filled histograms represent the SM backgrounds. Signal examples for SSM W' bosons with masses of 0.6, 1.0, 4.0, and 5.0 TeV are shown with the open histograms. The lower panel shows the ratio of data to prediction, and the gray band represents the systematic uncertainties.
png pdf	Figure 3-b: The integral transverse mass distribution, where the value in each bin is equal to the number of events with transverse mass equal to or greater than the left of the bin. The lower panel shows the ratio of data to prediction, and the gray band represents the systematic uncertainties.
png pdf	Figure 4: Distribution of $ {p_{\mathrm {T}}} ^{{\tau}}$ in the control region. The black symbols with error bars show the data, while the histograms represent the SM backgrounds. The lower panel shows the ratio of data to prediction.
png pdf	Figure 5: Expected (black dashed line) and observed (black solid line) 95% CL upper limits on the cross section for the production of SSM W' boson. The shaded bands around the expected limit represent the one and two standard deviation (s.d.) uncertainty intervals. The NNLO theoretical cross section with the corresponding PDF uncertainty band is also shown.
png pdf	Figure 6: Expected (black dashed line) and observed (black solid line) 95% CL upper limits on the ratio of couplings as a function of the W' boson mass. The values above the observed limit contour are excluded. The shaded bands around the expected limit represent the one and two standard deviation (s.d.) uncertainty intervals.
png pdf	Figure 7: Left: The width of the W' boson as a function of $M_{{\mathrm {W}'}}$ and mixing angle $\cot\theta _{\mathrm {E}}$ in the NUGIM G(221) framework. Right: Expected (black dashed line) and observed (black solid line) 95% CL upper limits on the mixing angle $\cot\theta _{\mathrm {E}}$ as a function of the W' boson mass. The region left of the solid line is excluded. The shaded bands represent the one and two standard deviation (s.d.) uncertainty bands.
png pdf	Figure 7-a: The width of the W' boson as a function of $M_{{\mathrm {W}'}}$ and mixing angle $\cot\theta _{\mathrm {E}}$ in the NUGIM G(221) framework.
png pdf	Figure 7-b: Expected (black dashed line) and observed (black solid line) 95% CL upper limits on the mixing angle $\cot\theta _{\mathrm {E}}$ as a function of the W' boson mass. The region left of the solid line is excluded. The shaded bands represent the one and two standard deviation (s.d.) uncertainty bands.
png pdf	Figure 8: Expected (black dashed line) and observed (black solid line) 95% CL model-independent upper limits on the product of cross section, branching fraction, and acceptance for a resonance decaying into the $ {\tau} {\nu}$ channel. The shaded bands represent the one and two standard deviation (s.d.) uncertainty bands.

Tables
png pdf	Table 1: Expected yields for the signal and background events compared to the measured event yields in data, for three regions of ${m_{\mathrm {T}}}$. Also shown are the total systematic uncertainties in the estimate of the event numbers.

Summary

A search for new physics in final states with a hadronically decaying $\tau$ lepton and missing transverse momentum has been performed by the CMS experiment, using proton-proton collision data at the center-of-mass energy $\sqrt{s} = $ 13 TeV with an integrated luminosity of 35.9 fb$^{-1}$. No significant excess compared to the standard model expectation is observed in the transverse mass of the tau and missing transverse momentum. A sequential standard model W' boson is excluded in the mass range 0.4 $ < M_{\mathrm{W'}} < $ 4.0 TeV at 95% confidence level. Couplings that are weaker than assumed in the sequential standard model can be excluded down to values of $ 7 \times 10^{-2} $ for $M_{\mathrm{W'}} = $ 1 TeV. Within the nonuniversal gauge interaction SU(2)xSU(2)xU(1) model, the lower limit on the W' boson mass depends on the coupling constant and varies from 1.7 to 3.9 TeV at 95% confidence level. For $\cot\theta_{\mathrm{E}} > $ 1, these results obtained in the tau channel provide the most stringent constraints on this model to date. In addition, a model-independent limit is provided allowing the results to be interpreted in other models giving the same final state with similar kinematic distributions.

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, .[Erratum: \DOI10.1007/BF01556677]
2	C.-W. Chiang, N. G. Deshpande, X.-G. He, and J. Jiang	The family $ SU(2)_l \times SU(2)_h \times U(1) $ model	PRD 81 (2010) 015006	0911.1480
3	X. Li and E. Ma	Gauge model of generation nonuniversality	PRL 47 (1981) 1788
4	D. J. Muller and S. Nandi	Top flavor: a separate $ SU(2) $ for the third family	PLB 383 (1996) 345	hep-ph/9602390
5	E. Malkawi, T. M. P. Tait, and C. P. Yuan	A model of strong flavor dynamics for the top quark	PLB 385 (1996) 304	hep-ph/9603349
6	K. Hsieh, K. Schmitz, J.-H. Yu, and C. P. Yuan	Global analysis of general $ SU(2) \times SU(2) \times U(1) $ models with precision data	PRD 82 (2010) 035011	1003.3482
7	CMS Collaboration	Search for $ \mathrm{W'} $ decaying to tau lepton and neutrino in proton-proton collisions at $ \sqrt{s} = $ 8 TeV	PLB 755 (2016) 196	CMS-EXO-12-011 1508.04308
8	ATLAS Collaboration	Search for high-mass resonances decaying to $ \tau\nu $ in pp collisions at $ \sqrt{s} = $ 13 TeV with the ATLAS detector	PRL 120 (2018) 161802	1801.06992
9	CMS Collaboration	Search for high-mass resonances in final states with a lepton and missing transverse momentum at $ \sqrt{s} = $ 13 TeV	JHEP 06 (2018) 128	CMS-EXO-16-033 1803.11133
10	CMS Collaboration	Search for a heavy resonance decaying into a $ \mathrm{Z} $ boson and a vector boson in the $ \nu \bar{\nu} \mathrm{\mathrm{q}} \mathrm{\mathrm{\bar{q}}} $ final state	JHEP 07 (2018) 075	CMS-B2G-17-005 1803.03838
11	CMS Collaboration	Search for dijet resonances in proton-proton collisions at $ \sqrt{s} = $ 13 TeV and constraints on dark matter and other models	PLB 769 (2017) 520	CMS-EXO-16-032 1611.03568
12	CMS Collaboration	Search for heavy resonances decaying to a top quark and a bottom quark in the lepton+jets final state in proton-proton collisions at 13 TeV	PLB 777 (2018) 39	CMS-B2G-17-010 1708.08539
13	E. Boos, V. Bunichev, L. Dudko, and M. Perfilov	Interference between $ \mathrm{W'} $ and $ \mathrm{W} $ in single-top quark production processes	PLB 655 (2007) 245	hep-ph/0610080
14	T. Sjostrand et al.	An introduction to PYTHIA 8.2	Comp. Phys. Comm. 191 (2015) 159	1410.3012
15	R. D. Ball et al.	Impact of heavy quark masses on parton distributions and LHC phenomenology	NPB 849 (2011) 296	1101.1300
16	R. D. Ball et al.	Parton distributions with LHC data	NPB 867 (2013) 244	1207.1303
17	P. Skands, S. Carrazza, and J. Rojo	Tuning PYTHIA 8.1: the Monash 2013 tune	EPJC 74 (2014) 3024	1404.5630
18	R. Gavin, Y. Li, F. Petriello, and S. Quackenbush	$ \mathrm{W} $ physics at the LHC with FEWZ 2.1	CPC 184 (2013) 208	1201.5896
19	Y. Li and F. Petriello	Combining QCD and electroweak corrections to dilepton production in FEWZ	PRD 86 (2012) 094034	1208.5967
20	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
21	Y. G. Kim and K. Y. Lee	Early LHC bound on the $ \mathrm{W'} $ boson mass in the nonuniversal gauge interaction model	PLB 706 (2012) 367	1105.2653
22	L. Edelhauser and A. Knochel	Observing nonstandard $ \mathrm{W'} $ and $ \mathrm{Z'} $ through the third generation and Higgs lens		1408.0914
23	CMS Collaboration	The CMS trigger system	JINST 12 (2017) P01020	CMS-TRG-12-001 1609.02366
24	CMS Collaboration	The CMS experiment at the CERN LHC	JINST 3 (2008) S08004	CMS-00-001
25	J. Alwall et al.	Comparative study of various algorithms for the merging of parton showers and matrix elements in hadronic collisions	EPJC 53 (2008) 473	0706.2569
26	NNPDF Collaboration	Parton distributions for the LHC Run II	JHEP 04 (2015) 040	1410.8849
27	S. G. Bondarenko and A. A. Sapronov	NLO EW and QCD proton-proton cross section calculations with MCSANC-v1.01	CPC 184 (2013) 2343	1301.3687
28	J. R. Andersen et al.	Les Houches 2013: Physics at TeV colliders: Standard model working group report		1405.1067
29	S. Frixione, P. Nason, and C. Oleari	Matching NLO QCD computations with parton shower simulations: the POWHEG method	JHEP 11 (2007) 070	0709.2092
30	P. Nason	A new method for combining NLO QCD with shower Monte Carlo algorithms	JHEP 11 (2004) 040	hep-ph/0409146
31	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
32	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
33	E. Re	Single-top Wt-channel production matched with parton showers using the POWHEG method	EPJC 71 (2011) 1547	1009.2450
34	S. Frixione, P. Nason, and G. Ridolfi	A positive-weight next-to-leading-order Monte Carlo for heavy flavour hadroproduction	JHEP 09 (2007) 126	0707.3088
35	GEANT4 Collaboration	GEANT4--a simulation toolkit	NIMA 506 (2003) 250
36	CMS Collaboration	Particle-flow reconstruction and global event description with the CMS detector	JINST 12 (2017) P10003	CMS-PRF-14-001 1706.04965
37	CMS Collaboration	Performance of the CMS missing transverse momentum reconstruction in $ {\mathrm{p}}{\mathrm{p}} $ data at $ \sqrt{s} = $ 8 TeV	JINST 10 (2015) P02006	CMS-JME-13-003 1411.0511
38	M. Cacciari, G. P. Salam, and G. Soyez	The anti-$ {k_{\mathrm{T}}} $ jet clustering algorithm	JHEP 04 (2008) 063	0802.1189
39	M. Cacciari, G. P. Salam, and G. Soyez	FastJet user manual	EPJC 72 (2012) 1896	1111.6097
40	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
41	CMS Collaboration	Electron and photon performance in CMS with the full 2016 data sample	CDS
42	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
43	CMS Collaboration	Reconstruction and identification of $ \tau $ lepton decays to hadrons and $ \nu_{\tau} $ at CMS	JINST 11 (2016) P01019	CMS-TAU-14-001 1510.07488
44	CMS Collaboration	Performance of reconstruction and identification of $ \tau $ leptons in their decays to hadrons and $ \nu_{\tau} $ in LHC Run II	CMS-PAS-TAU-16-002	CMS-PAS-TAU-16-002
45	CMS Collaboration	Observation of the Higgs boson decay to a pair of $ \tau $ leptons with the CMS detector	PLB 779 (2018) 283	CMS-HIG-16-043 1708.00373
46	CMS Collaboration	Search for dark matter produced with an energetic jet or a hadronically decaying $ \mathrm{W} $ or $ \mathrm{Z} $ boson at $ \sqrt{s} = $ 13 TeV	JHEP 07 (2017) 014	CMS-EXO-16-037 1703.01651
47	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
48	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
49	M. Botje et al.	The PDF4LHC working group interim recommendations		1101.0538
50	S. Alekhin et al.	The PDF4LHC working group interim report		1101.0536
51	J. Butterworth et al.	PDF4LHC recommendations for LHC Run II	JPG 43 (2016) 023001	1510.03865
52	CMS Collaboration	Measurement of the inelastic proton-proton cross section at $ \sqrt{s} = $ 13 TeV	Submitted to \it JHEP	CMS-FSQ-15-005 1802.02613
53	CMS Collaboration	CMS luminosity measurement for the 2016 data taking period	CMS-PAS-LUM-17-001	CMS-PAS-LUM-17-001
54	G. Cowan	``Statistics", Ch. 39 in Particle Data Group, C. Patrignani et al., ``Review of particle physics"	CPC 40 (2016) 100001
55	M. Baak, S. Gadatsch, R. Harrington, and W. Verkerke	Interpolation between multi-dimensional histograms using a new non-linear moment morphing method	NIMA 771 (2015) 39	1410.7388
56	ATLAS Collaboration	Search for a new heavy gauge boson resonance decaying into a lepton and missing transverse momentum in 36 fb$^{-1}$ of pp collisions at $ \sqrt{s} = $ 13 TeV with the ATLAS experiment	EPJC 78 (2018) 401	1706.04786