Abstract
In this paper, we use the associated production of top-quark pairs (\( t\overline{t} \)) with a generic scalar boson (ϕ) at the LHC (pp → \( t\overline{t}\phi \)) to explore the sensitivity of a large set of observables to the sign of the CP mixing angle (α), present in the coupling between the scalar boson and the top quarks. The mass of the scalar boson is set to mϕ = 125 GeV (the Standard Model Higgs boson mass) and its coupling to top-quarks is varied such that α = 0°, 22.5°, 45.0°, 67.5°, 90.0°, 135.0° and 180.0°. Dileptonic final states of the \( t\overline{t}\phi \) system are used (pp → bℓ+νℓ\( \overline{b} \)ℓ−\( \overline{\nu} \)ℓb\( \overline{b} \)), where the scalar boson is expected to decay according to ϕ → \( b\overline{b} \). A new method to reconstruct the scalar mass, originally designed for the low mass regime is used, improving the resolution of the Higgs mass by roughly a factor of two. A full phenomenological analysis is performed using Standard Model (SM) background and signal events generated with MadGraph5_aMC@NLO, in turn reconstructed using a kinematical fit. The most sensitive CP-observables are selected to compute Confidence Level (CL) limits as a function of the sign of the top quark Yukawa couplings to the ϕ boson. We also explore the sensitivity to interference terms using differential distributions and angular asymmetries. Given the significant difference between the pure scalar (σ0+) and pure pseudo-scalar (σ0−) production cross section values, it is unlikely the \( t\overline{t}\phi \) channel alone will be sensitive to the sign of the CP-mixing angle or interference terms, even at the end of the LHC. Using the \( {b}_2^{t\overline{t}\phi } \) and \( {b}_4^{t\overline{t}\phi } \) variables, exclusion limits at 95% CL for the CP-even and CP-odd components of the top quark Yukawa couplings are expected to be set to \( \overset{\sim }{\kappa } \) ∈ [-0.698,+0.698] and |κ| ∈ [0.878,1.04], respectively, at the end of the High Luminosity phase of the LHC (HL-LHC) by using the dileptonic decay channel alone.
Article PDF
Similar content being viewed by others
Explore related subjects
Discover the latest articles, news and stories from top researchers in related subjects.Avoid common mistakes on your manuscript.
References
A.D. Sakharov, Violation of CP Invariance, C asymmetry, and baryon asymmetry of the universe, Pisma Zh. Eksp. Teor. Fiz. 5 (1967) 32 [INSPIRE].
ATLAS collaboration, Observation of a new particle in the search for the Standard Model Higgs boson with the ATLAS detector at the LHC, Phys. Lett. B 716 (2012) 1 [arXiv:1207.7214] [INSPIRE].
CMS collaboration, Observation of a New Boson at a Mass of 125 GeV with the CMS Experiment at the LHC, Phys. Lett. B 716 (2012) 30 [arXiv:1207.7235] [INSPIRE].
T.D. Lee, A Theory of Spontaneous T Violation, Phys. Rev. D 8 (1973) 1226 [INSPIRE].
I.F. Ginzburg, M. Krawczyk and P. Osland, Two Higgs doublet models with CP-violation, in International Workshop on Linear Colliders (LCWS 2002), (2002), pp. 703–706 [hep-ph/0211371] [INSPIRE].
W. Khater and P. Osland, CP violation in top quark production at the LHC and two Higgs doublet models, Nucl. Phys. B 661 (2003) 209 [hep-ph/0302004] [INSPIRE].
A.W. El Kaffas, P. Osland and O.M. Ogreid, CP violation, stability and unitarity of the two Higgs doublet model, Nonlin. Phenom. Complex Syst. 10 (2007) 347 [hep-ph/0702097] [INSPIRE].
B. Grzadkowski and P. Osland, Tempered Two-Higgs-Doublet Model, Phys. Rev. D 82 (2010) 125026 [arXiv:0910.4068] [INSPIRE].
A. Arhrib, E. Christova, H. Eberl and E. Ginina, CP violation in charged Higgs production and decays in the Complex Two Higgs Doublet Model, JHEP 04 (2011) 089 [arXiv:1011.6560] [INSPIRE].
A. Barroso, P.M. Ferreira, R. Santos and J.P. Silva, Probing the scalar-pseudoscalar mixing in the 125 GeV Higgs particle with current data, Phys. Rev. D 86 (2012) 015022 [arXiv:1205.4247] [INSPIRE].
S. Inoue, M.J. Ramsey-Musolf and Y. Zhang, CP-violating phenomenology of flavor conserving two Higgs doublet models, Phys. Rev. D 89 (2014) 115023 [arXiv:1403.4257] [INSPIRE].
K. Cheung, J.S. Lee, E. Senaha and P.-Y. Tseng, Confronting Higgcision with Electric Dipole Moments, JHEP 06 (2014) 149 [arXiv:1403.4775] [INSPIRE].
D. Fontes, J.C. Romão and J.P. Silva, h → Zγ in the complex two Higgs doublet model, JHEP 12 (2014) 043 [arXiv:1408.2534] [INSPIRE].
D. Fontes, J.C. Romão, R. Santos and J.P. Silva, Large pseudoscalar Yukawa couplings in the complex 2HDM, JHEP 06 (2015) 060 [arXiv:1502.01720] [INSPIRE].
C.-Y. Chen, S. Dawson and Y. Zhang, Complementarity of LHC and EDMs for Exploring Higgs CP-violation, JHEP 06 (2015) 056 [arXiv:1503.01114] [INSPIRE].
M. Mühlleitner, M.O.P. Sampaio, R. Santos and J. Wittbrodt, Phenomenological Comparison of Models with Extended Higgs Sectors, JHEP 08 (2017) 132 [arXiv:1703.07750] [INSPIRE].
D. Fontes, M. Mühlleitner, J.C. Romão, R. Santos, J.P. Silva and J. Wittbrodt, The C2HDM revisited, JHEP 02 (2018) 073 [arXiv:1711.09419] [INSPIRE].
J.F. Gunion and X.-G. He, Determining the CP nature of a neutral Higgs boson at the LHC, Phys. Rev. Lett. 76 (1996) 4468 [hep-ph/9602226] [INSPIRE].
F. Boudjema, R.M. Godbole, D. Guadagnoli and K.A. Mohan, Lab-frame observables for probing the top-Higgs interaction, Phys. Rev. D 92 (2015) 015019 [arXiv:1501.03157] [INSPIRE].
S.P. Amor dos Santos et al., Angular distributions in \( t\overline{t}H \)(H → \( b\overline{b} \)) reconstructed events at the LHC, Phys. Rev. D 92 (2015) 034021 [arXiv:1503.07787] [INSPIRE].
S. Amor Dos Santos et al., Probing the CP nature of the Higgs coupling in \( t\overline{t}h \) events at the LHC, Phys. Rev. D 96 (2017) 013004 [arXiv:1704.03565] [INSPIRE].
S. Berge, W. Bernreuther and J. Ziethe, Determining the CP parity of Higgs bosons at the LHC in their tau decay channels, Phys. Rev. Lett. 100 (2008) 171605 [arXiv:0801.2297] [INSPIRE].
S. Berge and W. Bernreuther, Determining the CP parity of Higgs bosons at the LHC in the tau to 1-prong decay channels, Phys. Lett. B 671 (2009) 470 [arXiv:0812.1910] [INSPIRE].
S. Berge, W. Bernreuther, B. Niepelt and H. Spiesberger, How to pin down the CP quantum numbers of a Higgs boson in its tau decays at the LHC, Phys. Rev. D 84 (2011) 116003 [arXiv:1108.0670] [INSPIRE].
S. Berge, W. Bernreuther and S. Kirchner, Determination of the Higgs CP-mixing angle in the tau decay channels at the LHC including the Drell-Yan background, Eur. Phys. J. C 74 (2014) 3164 [arXiv:1408.0798] [INSPIRE].
S. Berge, W. Bernreuther and S. Kirchner, Prospects of constraining the Higgs boson’s CP nature in the tau decay channel at the LHC, Phys. Rev. D 92 (2015) 096012 [arXiv:1510.03850] [INSPIRE].
CMS collaboration, Measurements of \( t\overline{t}H \) Production and the CP Structure of the Yukawa Interaction between the Higgs Boson and Top Quark in the Diphoton Decay Channel, Phys. Rev. Lett. 125 (2020) 061801 [arXiv:2003.10866] [INSPIRE].
ATLAS collaboration, CP Properties of Higgs Boson Interactions with Top Quarks in the \( t\overline{t}H \) and tH Processes Using H → γγ with the ATLAS Detector, Phys. Rev. Lett. 125 (2020) 061802 [arXiv:2004.04545] [INSPIRE].
CMS collaboration, Analysis of the CP structure of the Yukawa coupling between the Higgs boson and τ leptons in proton-proton collisions at \( \sqrt{s} \) = 13 TeV, Tech. Rep. CMS-PAS-HIG-20-006 CERN, Geneva (2020).
T. Ghosh, R. Godbole and X. Tata, Determining the spacetime structure of bottom-quark couplings to spin-zero particles, Phys. Rev. D 100 (2019) 015026 [arXiv:1904.09895] [INSPIRE].
D. Azevedo, R. Capucha, A. Onofre and R. Santos, Scalar mass dependence of angular variables in \( t\overline{t}\phi \) production, JHEP 06 (2020) 155 [arXiv:2003.09043] [INSPIRE].
R. Alonso, C. Fraser-Taliente, C. Hays and M. Spannowsky, Prospects for direct CP tests of hqq interactions, JHEP 08 (2021) 167 [arXiv:2105.06879] [INSPIRE].
C. Grojean, A. Paul and Z. Qian, Resurrecting \( b\overline{b}h \) with kinematic shapes, JHEP 04 (2021) 139 [arXiv:2011.13945] [INSPIRE].
D. Huang, A.P. Morais and R. Santos, CP violating hW+W− coupling in the Standard Model and beyond, JHEP 01 (2021) 168 [arXiv:2009.09228] [INSPIRE].
H.E. Haber, V. Keus and R. Santos, P-even, CP-violating Signals in Scalar-Mediated Processes, arXiv:2206.09643 [INSPIRE].
J. Hermann, D. Stremmer and M. Worek, \( \mathcal{CP} \) structure of the top-quark Yukawa interaction: NLO QCD corrections and off-shell effects, arXiv:2205.09983 [INSPIRE].
A.V. Gritsan, J. Roskes, U. Sarica, M. Schulze, M. Xiao and Y. Zhou, New features in the JHU generator framework: constraining Higgs boson properties from on-shell and off-shell production, Phys. Rev. D 102 (2020) 056022 [arXiv:2002.09888] [INSPIRE].
A. Bhardwaj, C. Englert, R. Hankache and A.D. Pilkington, Machine-enhanced CP-asymmetries in the Higgs sector, Phys. Lett. B 832 (2022) 137246 [arXiv:2112.05052] [INSPIRE].
J. Ellis, D.S. Hwang, K. Sakurai and M. Takeuchi, Disentangling Higgs-Top Couplings in Associated Production, JHEP 04 (2014) 004 [arXiv:1312.5736] [INSPIRE].
D. Gonçalves, K. Kong and J.H. Kim, Probing the top-Higgs Yukawa CP structure in dileptonic \( t\overline{t}h \) with M2-assisted reconstruction, JHEP 06 (2018) 079 [arXiv:1804.05874] [INSPIRE].
D. Gonçalves, J.H. Kim, K. Kong and Y. Wu, Direct Higgs-top CP-phase measurement with \( t\overline{t}h \) at the 14 TeV LHC and 100 TeV FCC, JHEP 01 (2022) 158 [arXiv:2108.01083] [INSPIRE].
W. Bernreuther and A. Brandenburg, Tracing CP-violation in the production of top quark pairs by multiple TeV proton proton collisions, Phys. Rev. D 49 (1994) 4481 [hep-ph/9312210] [INSPIRE].
P.S. Bhupal Dev, A. Djouadi, R.M. Godbole, M.M. Muhlleitner and S.D. Rindani, Determining the CP properties of the Higgs boson, Phys. Rev. Lett. 100 (2008) 051801 [arXiv:0707.2878] [INSPIRE].
R. Frederix, S. Frixione, V. Hirschi, F. Maltoni, R. Pittau and P. Torrielli, Scalar and pseudoscalar Higgs production in association with a top-antitop pair, Phys. Lett. B 701 (2011) 427 [arXiv:1104.5613] [INSPIRE].
S. Khatibi and M. Mohammadi Najafabadi, Exploring the Anomalous Higgs-top Couplings, Phys. Rev. D 90 (2014) 074014 [arXiv:1409.6553] [INSPIRE].
F. Demartin, F. Maltoni, K. Mawatari, B. Page and M. Zaro, Higgs characterisation at NLO in QCD: CP properties of the top-quark yukawa interaction, Eur. Phys. J. C 74 (2014).
A. Kobakhidze, L. Wu and J. Yue, Anomalous Top-Higgs Couplings and Top Polarisation in Single Top and Higgs Associated Production at the LHC, JHEP 10 (2014) 100 [arXiv:1406.1961] [INSPIRE].
J. Bramante, A. Delgado and A. Martin, Cornering a hyper Higgs boson: Angular kinematics for boosted Higgs bosons with top pairs, Phys. Rev. D 89 (2014) 093006 [arXiv:1402.5985] [INSPIRE].
X.-G. He, G.-N. Li and Y.-J. Zheng, Probing Higgs boson CP Properties with \( t\overline{t}H \) at the LHC and the 100 TeV pp collider, Int. J. Mod. Phys. A 30 (2015) 1550156 [arXiv:1501.00012] [INSPIRE].
A.V. Gritsan, R. Röntsch, M. Schulze and M. Xiao, Constraining anomalous Higgs boson couplings to the heavy flavor fermions using matrix element techniques, Phys. Rev. D 94 (2016) 055023 [arXiv:1606.03107] [INSPIRE].
M.J. Dolan, M. Spannowsky, Q. Wang and Z.-H. Yu, Determining the quantum numbers of simplified models in \( t\overline{t}X \) production at the LHC, Phys. Rev. D 94 (2016) 015025 [arXiv:1606.00019] [INSPIRE].
D. Gonçalves and D. López-Val, Pseudoscalar searches with dileptonic tops and jet substructure, Phys. Rev. D 94 (2016) 095005 [arXiv:1607.08614] [INSPIRE].
M.R. Buckley and D. Gonçalves, Constraining the Strength and CP Structure of Dark Production at the LHC: the Associated Top-Pair Channel, Phys. Rev. D 93 (2016) 034003 [arXiv:1511.06451] [INSPIRE].
N. Mileo, K. Kiers, A. Szynkman, D. Crane and E. Gegner, Pseudoscalar top-Higgs coupling: exploration of CP-odd observables to resolve the sign ambiguity, JHEP 07 (2016) 056 [arXiv:1603.03632] [INSPIRE].
M.R. Buckley and D. Gonçalves, Boosting the Direct CP Measurement of the Higgs-Top Coupling, Phys. Rev. Lett. 116 (2016) 091801 [arXiv:1507.07926] [INSPIRE].
D. Azevedo, A. Onofre, F. Filthaut and R. Gonçalo, CP tests of Higgs couplings in \( t\overline{t}h \) semileptonic events at the LHC, Phys. Rev. D 98 (2018) 033004 [arXiv:1711.05292] [INSPIRE].
J. Li, Z.-g. Si, L. Wu and J. Yue, Central-edge asymmetry as a probe of Higgs-top coupling in \( t\overline{t}h \) production at the LHC, Phys. Lett. B 779 (2018) 72 [arXiv:1701.00224] [INSPIRE].
A. Ferroglia, M.C.N. Fiolhais, E. Gouveia and A. Onofre, Role of the \( t\overline{t}h \) rest frame in direct top-quark Yukawa coupling measurements, Phys. Rev. D 100 (2019) 075034 [arXiv:1909.00490] [INSPIRE].
D.A. Faroughy, J.F. Kamenik, N. Košnik and A. Smolkovič, Probing the CP nature of the top quark Yukawa at hadron colliders, JHEP 02 (2020) 085 [arXiv:1909.00007] [INSPIRE].
D. Azevedo, R. Capucha, E. Gouveia, A. Onofre and R. Santos, Light Higgs searches in \( t\overline{t}\phi \) production at the LHC, JHEP 04 (2021) 077 [arXiv:2012.10730] [INSPIRE].
H. Bahl et al., Indirect \( \mathcal{CP} \) probes of the Higgs-top-quark interaction: current LHC constraints and future opportunities, JHEP 11 (2020) 127 [arXiv:2007.08542] [INSPIRE].
H. Bahl and S. Brass, Constraining \( \mathcal{CP} \)-violation in the Higgs-top-quark interaction using machine-learning-based inference, JHEP 03 (2022) 017 [arXiv:2110.10177] [INSPIRE].
B. Bortolato, J.F. Kamenik, N. Košnik and A. Smolkovič, Optimized probes of CP-odd effects in the \( t\overline{t}h \) process at hadron colliders, Nucl. Phys. B 964 (2021) 115328 [arXiv:2006.13110] [INSPIRE].
Q.-H. Cao, K.-P. Xie, H. Zhang and R. Zhang, A New Observable for Measuring CP Property of Top-Higgs Interaction, Chin. Phys. C 45 (2021) 023117 [arXiv:2008.13442] [INSPIRE].
R.K. Barman, D. Gonçalves and F. Kling, Machine learning the Higgs boson-top quark CP phase, Phys. Rev. D 105 (2022) 035023 [arXiv:2110.07635] [INSPIRE].
G. Durieux and Y. Grossman, Probing CP-violation systematically in differential distributions, Phys. Rev. D 92 (2015) 076013 [arXiv:1508.03054] [INSPIRE].
J. Alwall, M. Herquet, F. Maltoni, O. Mattelaer and T. Stelzer, MadGraph 5: Going Beyond, JHEP 06 (2011) 128 [arXiv:1106.0522] [INSPIRE].
P. Artoisenet et al., A framework for Higgs characterisation, JHEP 11 (2013) 043 [arXiv:1306.6464] [INSPIRE].
T. Sjöstrand, S. Mrenna and P.Z. Skands, PYTHIA 6.4 Physics and Manual, JHEP 05 (2006) 026 [hep-ph/0603175] [INSPIRE].
DELPHES 3 collaboration, DELPHES 3, A modular framework for fast simulation of a generic collider experiment, JHEP 02 (2014) 057 [arXiv:1307.6346] [INSPIRE].
E. Conte, B. Fuks and G. Serret, MadAnalysis 5, A User-Friendly Framework for Collider Phenomenology, Comput. Phys. Commun. 184 (2013) 222 [arXiv:1206.1599] [INSPIRE].
A.L. Read, Presentation of search results: The CL(s) technique, J. Phys. G 28 (2002) 2693 [INSPIRE].
T. Junk, Confidence level computation for combining searches with small statistics, Nucl. Instrum. Meth. A 434 (1999) 435 [hep-ex/9902006] [INSPIRE].
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
ArXiv ePrint: 2208.04271
Rights and permissions
Open Access . This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.
About this article
Cite this article
Azevedo, D., Capucha, R., Onofre, A. et al. CP-violation, asymmetries and interferences in \( t\overline{t}\phi \). J. High Energ. Phys. 2022, 246 (2022). https://doi.org/10.1007/JHEP09(2022)246
Received:
Accepted:
Published:
DOI: https://doi.org/10.1007/JHEP09(2022)246