CMS-PAS-FTR-22-002 | ||
Search for a vector-like quark T decaying to bW, tZ, tH in the single lepton final state at the HL-LHC | ||
CMS Collaboration | ||
2 December 2022 | ||
Abstract: A simulation-based projection study is presented for a search for a vector-like top quark partner T in proton-proton (pp) collisions at $ {\sqrt{\text{s}}} = $ 14 TeV. The search considers the operational conditions of the High-Luminosity LHC (HL-LHC). The production $ {\text{pp} \rightarrow \text{T}\bar{\text{T}}} $ is followed by the decays $ {\text{T} \rightarrow \text{bW}} $, $ {\text{T} \rightarrow \text{tH}} $, and $ {\text{T} \rightarrow \text{tZ}} $ with equal branching fractions of 1/3. Events with one electron or muon, missing transverse momentum and jets are considered. For an integrated luminosity of 3000 fb$ ^{-1} $, the search projects to exclude a T mass below 1750 GeV at the 95% confidence level assuming equal branching fractions for $ {\text{T}\rightarrow \text{bW}/\text{tH}/\text{tZ}} $. Conversely, a T quark with mass up to 1440 GeV can be discovered at the HL-LHC with a significance of five standard deviations. | ||
Links: CDS record (PDF) ; CADI line (restricted) ; |
Figures | |
png pdf |
Figure 1:
Leading-order Feynman diagrams showing $ \mathrm{T}\overline{\mathrm{T}} $ production along with the subsequent decays $ \mathrm{T}\rightarrow \mathrm{b}\mathrm{W} $ (left), $ \mathrm{T}\rightarrow \mathrm{t}\mathrm{Z} $ (middle) and $ \mathrm{T}\rightarrow \mathrm{t}\mathrm{H} $ (right). |
png pdf |
Figure 1-a:
Leading-order Feynman diagrams showing $ \mathrm{T}\overline{\mathrm{T}} $ production along with the subsequent decay $ \mathrm{T}\rightarrow \mathrm{b}\mathrm{W} $. |
png pdf |
Figure 1-b:
Leading-order Feynman diagrams showing $ \mathrm{T}\overline{\mathrm{T}} $ production along with the subsequent decay $ \mathrm{T}\rightarrow \mathrm{t}\mathrm{Z} $. |
png pdf |
Figure 1-c:
Leading-order Feynman diagrams showing $ \mathrm{T}\overline{\mathrm{T}} $ production along with the subsequent decay $ \mathrm{T}\rightarrow \mathrm{t}\mathrm{H} $. |
png pdf |
Figure 2:
Number of AK4 jets (left) and b-tagged AK4 jets (right) for signal and background processes. The signal distributions are scaled by factors of 20, 2000 and 200'000, depending on the T mass. |
png pdf |
Figure 2-a:
Number of AK4 jets for signal and background processes. The signal distributions are scaled by factors of 20, 2000 and 200'000, depending on the T mass. |
png pdf |
Figure 2-b:
Number of b-tagged AK4 jets for signal and background processes. The signal distributions are scaled by factors of 20, 2000 and 200'000, depending on the T mass. |
png pdf |
Figure 3:
Multiplicity for the W-tagged (top), single b-tagged H (bottom left) and doubly b-tagged H AK8 jets (bottom right). The signal distributions are scaled by factors of 20, 2000 and 200'000, depending on the T mass. |
png pdf |
Figure 3-a:
Multiplicity for the W-tagged AK8 jets. The signal distributions are scaled by factors of 20, 2000 and 200'000, depending on the T mass. |
png pdf |
Figure 3-b:
Multiplicity for the single b-tagged H AK8 jets. The signal distributions are scaled by factors of 20, 2000 and 200'000, depending on the T mass. |
png pdf |
Figure 3-c:
Multiplicity for the doubly b-tagged H AK8 jets. The signal distributions are scaled by factors of 20, 2000 and 200'000, depending on the T mass. |
png pdf |
Figure 4:
Distributions in $ S_{\text{T}} $ for signal and background processes. The signal distributions are scaled by factors of 20, 2000 and 200\,000, depending on the T mass. |
png pdf |
Figure 5:
Expected upper limits at 95% CL on the $ \mathrm{T}\overline{\mathrm{T}} $ production cross section. The inner (green) and the outer (yellow) bands indicate the regions containing 68 and 95%, respectively, of the distribution of limits expected under the background-only hypothesis. |
png pdf |
Figure 6:
Projected exclusion limits at 95% CL on the T mass (left) and the expected discovery significances (right), as a function of integrated luminosity at the HL-LHC, assuming equal branching fractions for $ {\mathrm{T}\rightarrow \mathrm{b}\mathrm{W}} $, $ {\mathrm{T}\rightarrow \mathrm{t}\mathrm{H}} $, and $ {\mathrm{T}\rightarrow \mathrm{t}\mathrm{Z}} $ decays. |
png pdf |
Figure 6-a:
Projected exclusion limits at 95% CL on the T mass, as a function of integrated luminosity at the HL-LHC, assuming equal branching fractions for $ {\mathrm{T}\rightarrow \mathrm{b}\mathrm{W}} $, $ {\mathrm{T}\rightarrow \mathrm{t}\mathrm{H}} $, and $ {\mathrm{T}\rightarrow \mathrm{t}\mathrm{Z}} $ decays. |
png pdf |
Figure 6-b:
Expected discovery significances, as a function of integrated luminosity at the HL-LHC, assuming equal branching fractions for $ {\mathrm{T}\rightarrow \mathrm{b}\mathrm{W}} $, $ {\mathrm{T}\rightarrow \mathrm{t}\mathrm{H}} $, and $ {\mathrm{T}\rightarrow \mathrm{t}\mathrm{Z}} $ decays. |
png pdf |
Figure 7:
Discovery potential of a fermionic top partner T as a function of T mass versus integrated luminosity. The blue dashed and red solid lines represent discoveries at expected significances of three and five standard deviations, respectively. |
Tables | |
png pdf |
Table 1:
Definition of eight exclusive SRs on the basis of number of H-tagged, W-tagged, and b-tagged jets in the event. |
png pdf |
Table 2:
Summary of the systematic uncertainties used in this analysis and their effect on signal cross-section. |
Summary |
This study presented the expected sensitivity of the CMS experiment to a $ \mathrm{T}\overline{\mathrm{T}} $ production in single lepton final states, considering the subsequent decays $ \mathrm{T}\rightarrow \mathrm{b}\mathrm{W} $, $ \mathrm{T}\rightarrow \mathrm{t}\mathrm{H} $, and $ \mathrm{T}\rightarrow \mathrm{t}\mathrm{Z} $, with a dataset of 3000 fb$ ^{-1} $ of 14 TeV proton proton collisions, expected to be collected at the LHC. The signal and background samples have been simulated with DELPHES 3 considering the CMS Phase-2 detector geometry. At 95% CL, the study projects to exclude a T mass up to 1750 GeV, which is significantly higher than the existing Run 2 results. With 3000 fb$ ^{-1} $, this study shows the prospect for a T discovery up to masses of 1440 GeV. |
References | ||||
1 | ATLAS Collaboration | Observation of a new particle in the search for the Standard Model Higgs boson with the ATLAS detector at the LHC | PLB 716 (2012) 1 | 1207.7214 |
2 | CMS Collaboration | Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC | PLB 716 (2012) 30 | CMS-HIG-12-028 1207.7235 |
3 | CMS Collaboration | Observation of a new boson with mass near 125 GeV in $ pp $ collisions at $ \sqrt{s} = $ 7 and 8 TeV | JHEP 06 (2013) 081 | CMS-HIG-12-036 1303.4571 |
4 | L. Susskind | Dynamics of spontaneous symmetry breaking in the Weinberg-Salam theory | PRD 20 (1979) 2619 | |
5 | M. Perelstein, M. E. Peskin, and A. Pierce | Top quarks and electroweak symmetry breaking in little Higgs models | PRD 69 (2004) 075002 | hep-ph/0310039 |
6 | O. Matsedonskyi, G. Panico, and A. Wulzer | Light top partners for a light composite Higgs | JHEP 01 (2013) 164 | 1204.6333 |
7 | M. Schmaltz and D. Tucker-Smith | Little Higgs review | Ann. Rev. Nucl. Part. Sci. 55 (2005) 229 | hep-ph/0502182 |
8 | R. Contino, L. Da Rold, and A. Pomarol | Light custodians in natural composite Higgs models | PRD 75 (2007) 055014 | hep-ph/0612048 |
9 | R. Contino, T. Kramer, M. Son, and R. Sundrum | Warped/composite phenomenology simplified | JHEP 05 (2007) 074 | hep-ph/0612180 |
10 | D. B. Kaplan | Flavor at SSC energies: A new mechanism for dynamically generated fermion masses | NPB 365 (1991) 259 | |
11 | M. J. Dugan, H. Georgi, and D. B. Kaplan | Anatomy of a composite Higgs model | NPB 254 (1985) 299 | |
12 | F. del Aguila, L. Ametller, G. L. Kane, and J. Vidal | Vector like fermion and standard Higgs production at hadron colliders | NPB 334 (1990) 1 | |
13 | A. De Simone, O. Matsedonskyi, R. Rattazzi, and A. Wulzer | A first top partner hunter's guide | JHEP 04 (2013) 004 | 1211.5663 |
14 | CMS Collaboration | Search for vector-like T and B quark pairs in final states with leptons at $ \sqrt{s} = $ 13 TeV | JHEP 08 (2018) 177 | 1805.04758 |
15 | CMS Collaboration | Technical proposal for the Phase-II upgrade of the CMS detector | \ CERN-LHCC-2015-010, LHCC-P-008, CMS-TDR-15-02, CERN, Geneva, 2015 link |
|
16 | CMS Collaboration | The Phase-2 upgrade of the CMS barrel calorimeters | \ CERN-LHCC-2017-011, CMS-TDR-015, CERN, Geneva, 2017 CDS |
|
17 | CMS Collaboration | The Phase-2 upgrade of the CMS muon detectors | \ CERN-LHCC-2017-012, CMS-TDR-016, CERN, Geneva, 2017 CDS |
|
18 | CMS Collaboration | The Phase-2 upgrade of the CMS endcap calorimeter | \ CERN-LHCC-2017-023, CMS-TDR-019, CERN, Geneva, 2017 link |
|
19 | CMS Collaboration | A MIP timing detector for the CMS Phase-2 upgrade | CERN-LHCC-2019-003, CMS-TDR-020 CDS |
|
20 | CMS Collaboration | The Phase-2 upgrade of the CMS Level-1 trigger | CERN-LHCC-2020-004, CMS-TDR-021 CDS |
|
21 | CMS Collaboration | The Phase-2 upgrade of the CMS data acquisition and high level trigger | CERN-LHCC-2021-007, CMS-TDR-022 CDS |
|
22 | CMS Collaboration | Expected performance of the physics objects with the upgraded CMS detector at the HL-LHC | CMS-NOTE-2018-006, CERN-CMS-NOTE-2018-006 CDS |
|
23 | 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 |
24 | T. Sjöstrand, S. Mrenna, and P. Z. Skands | A brief introduction to PYTHIA 8.1 | Comput. Phys. Commun. 178 (2008) 852 | 0710.3820 |
25 | M. Czakon, P. Fiedler, and A. Mitov | Total top-quark pair-production cross section at hadron colliders through $ \mathcal{O}(\alpha^4_s) $ | PRL 110 (2013) 252004 | 1303.6254 |
26 | DELPHES 3 Collaboration | DELPHES 3, a modular framework for fast simulation of a generic collider experiment | JHEP 02 (2014) 057 | 1307.6346 |
27 | CMS Collaboration | Particle-flow event reconstruction in CMS and performance for jets, taus, and met | \ , CERN, Geneva, 2009 CMS-PAS-PFT-09-001 |
|
28 | M. Cacciari, G. P. Salam, and G. Soyez | The anti-$ k_{\mathrm{T}} $ jet clustering algorithm | JHEP 04 (2008) 063 | 0802.1189 |
29 | D. Bertolini, P. Harris, M. Low, and N. Tran | Pileup per particle identification | JHEP 10 (2014) 059 | 1407.6013 |
30 | A. J. Larkoski, S. Marzani, G. Soyez, and J. Thaler | Soft drop | JHEP 05 (2014) 146 | 1402.2657 |
31 | J. Thaler and K. Van Tilburg | Identifying boosted objects with $ N $-subjettiness | JHEP 03 (2011) 015 | 1011.2268 |
32 | E. X. Cid Vidal et al. | Beyond the Standard Model physics at the HL-LHC and HE-LHC | CERN Yellow Reports, 2019 Monographs 7 (2019) 585 |
|
33 | G. Cowan, K. Cranmer, E. Gross, and O. Vitells | Asymptotic formulae for likelihood-based tests of new physics | EPJC 71 (2011) 1554 | 1007.1727 |
Compact Muon Solenoid LHC, CERN |