scholarly journals Top-philic heavy resonances in four-top final states and their EFT interpretation

2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
Luc Darmé ◽  
Benjamin Fuks ◽  
Fabio Maltoni
Keyword(s):  
Top Quark ◽  
Top Quarks ◽  
New Physics ◽  
Effective Field ◽  
Effective Theory ◽  
Final States ◽  
Large Transverse Momentum ◽  
Simplified Models ◽  
Quark Pairs ◽  
Heavy Resonances

Abstract With an expected rate of about one event per 100,000 top-quark pairs, four top-quark final states very rarely arise at the LHC. Though scarce, they offer a unique window onto top-quark compositeness, self-interactions and more generically, onto any top-philic new physics. By employing simplified models featuring heavy resonances, we study the range of validity of effective theory interpretations of current four top-quark analyses at the LHC and establish their future reach at the HL-LHC. We find that for the class of models under consideration, the effective field theory interpretations are not applicable. We therefore present the most up-to-date limits obtained from public CMS analyses using simplified models. Finally, we put forward a novel recasting strategy for the experimental results based on the production of top quarks with large transverse momentum.

scholarly journals Search for new physics in top quark production with additional leptons in proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV using effective field theory

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
A. M. Sirunyan ◽  
◽  
A. Tumasyan ◽  
W. Adam ◽  
T. Bergauer ◽  
...  
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Top Quark ◽  
Center Of Mass ◽  
Top Quarks ◽  
New Physics ◽  
Effective Field ◽  
Proton Proton ◽  
Proton Collisions ◽  
Proton Proton Collisions

Abstract Events containing one or more top quarks produced with additional prompt leptons are used to search for new physics within the framework of an effective field theory (EFT). The data correspond to an integrated luminosity of 41.5 fb−1 of proton-proton collisions at a center-of-mass energy of 13 TeV at the LHC, collected by the CMS experiment in 2017. The selected events are required to have either two leptons with the same charge or more than two leptons; jets, including identified bottom quark jets, are also required, and the selected events are divided into categories based on the multiplicities of these objects. Sixteen dimension-six operators that can affect processes involving top quarks produced with additional charged leptons are considered in this analysis. Constructed to target EFT effects directly, the analysis applies a novel approach in which the observed yields are parameterized in terms of the Wilson coefficients (WCs) of the EFT operators. A simultaneous fit of the 16 WCs to the data is performed and two standard deviation confidence intervals for the WCs are extracted; the standard model expectations for the WC values are within these intervals for all of the WCs probed.

scholarly journals REVIEW OF TOP QUARK PHYSICS RESULTS

2008 ◽  
Vol 23 (03n04) ◽  
pp. 353-471 ◽  
Author(s):  
R. KEHOE ◽  
M. NARAIN ◽  
A. KUMAR
Keyword(s):  
Top Quark ◽  
Direct Determination ◽  
Top Quarks ◽  
New Physics ◽  
Boson Mass ◽  
Strong Interactions ◽  
Fundamental Parameter ◽  
Final States ◽  
Top Quark Mass ◽  
Fundamental Particle

As the heaviest known fundamental particle, the top quark has taken a central role in the study of fundamental interactions. Production of top quarks in pairs provides an important probe of strong interactions. The top quark mass is a key fundamental parameter which places a valuable constraint on the Higgs boson mass and electroweak symmetry breaking. Observations of the relative rates and kinematics of top quark final states constrain potential new physics. In many cases, the tests available with study of the top quark are both critical and unique. Large increases in data samples from the Fermilab Tevatron have been coupled with major improvements in experimental techniques to produce many new precision measurements of the top quark. The first direct evidence for electroweak production of top quarks has been obtained, with a resulting direct determination of Vtb. Several of the properties of the top quark have been measured. Progress has also been made in obtaining improved limits on potential anomalous production and decay mechanisms. This review presents an overview of recent theoretical and experimental developments in this field. We also provide a brief discussion of the implications for further efforts.

scholarly journals Probing effective field theory operators in the associated production of top quarks with a Z boson in multilepton final states at $$ \sqrt{s} $$ = 13 TeV

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
◽  
N. Tonon ◽  
H. Aarup Petersen ◽  
M. Aldaya Martin ◽  
P. Asmuss ◽  
...  
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Top Quark ◽  
Z Boson ◽  
Top Quarks ◽  
Effective Field ◽  
Machine Learning Techniques ◽  
Final States ◽  
Associated Production ◽  
Five Dimension

Abstract A search for new top quark interactions is performed within the framework of an effective field theory using the associated production of either one or two top quarks with a Z boson in multilepton final states. The data sample corresponds to an integrated luminosity of 138 fb−1 of proton-proton collisions at $$ \sqrt{s} $$ s = 13 TeV collected by the CMS experiment at the LHC. Five dimension-six operators modifying the electroweak interactions of the top quark are considered. Novel machine-learning techniques are used to enhance the sensitivity to effects arising from these operators. Distributions used for the signal extraction are parameterized in terms of Wilson coefficients describing the interaction strengths of the operators. All five Wilson coefficients are simultaneously fit to data and 95% confidence level intervals are computed. All results are consistent with the SM expectations.

scholarly journals Leading Weak Corrections to the Production of Heavy Top Quarks at Hadron Colliders

1997 ◽  
Vol 12 (07) ◽  
pp. 1341-1372 ◽  
Author(s):  
Chung Kao ◽  
G. A. Ladinsky ◽  
C.-P. Yuan
Keyword(s):  
Higgs Boson ◽  
Parity Violation ◽  
Top Quark ◽  
Top Quarks ◽  
New Physics ◽  
Threshold Region ◽  
Hadron Colliders ◽  
Top Quark Mass ◽  
Quark Pairs ◽  
The Standard Model

We calculate the leading weak corrections at [Formula: see text] to the QCD production of heavy top quark pairs via [Formula: see text] at hadron colliders and compare them with the complete one-loop weak corrections. We find that these corrections dominate the threshold region for a heavy top quark if the Higgs boson is light. For a heavy Higgs boson, these corrections are generally small. The chromo-anapole form factor of the top quark and effects of parity violation are studied in the Standard Model (SM). The parity violation effect in [Formula: see text] from the SM weak corrections is found to be very small, so any observation of large parity violation in this process would indicate new physics. The polarization of the [Formula: see text] pairs is also discussed, including the effect that this has on proposed techniques for measuring the top quark mass.

scholarly journals Measurement of the W boson helicity fractions in the decays of top quark pairs to lepton + jets final states produced in pp collisions at s=8TeV

2016 ◽  
Vol 762 ◽  
pp. 512-534 ◽  
Author(s):  
V. Khachatryan ◽  
A.M. Sirunyan ◽  
A. Tumasyan ◽  
W. Adam ◽  
E. Asilar ◽  
...  
Keyword(s):  
Top Quark ◽  
W Boson ◽  
Final States ◽  
Pp Collisions ◽  
Quark Pairs ◽  
Lepton Jets ◽  
Top Quark Pairs

scholarly journals TOP QUARK PHYSICS AT THE TEVATRON

2013 ◽  
Vol 28 (08) ◽  
pp. 1330013 ◽  
Author(s):  
FRÉDÉRIC DÉLIOT ◽  
YVONNE PETERS ◽  
VERONICA SORIN
Keyword(s):  
Top Quark ◽  
Top Quarks ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Proton Antiproton ◽  
New Methods ◽  
Decay Properties ◽  
Large Program ◽  
The Standard Model ◽  
New Phenomena

The heaviest known elementary particle, the top quark, was discovered in 1995 by the CDF and D0 collaborations at the Tevatron proton–antiproton collider at Fermilab. Since its discovery, a large program was set in motion by the CDF and D0 collaborations to characterize the production and decay properties of top quarks, and investigate their potential for searches of new phenomena beyond the standard model. During the past 20 years, new methods were developed and implemented to improve the measurements and searches for new physics in the top quark sector. This paper reviews the achievements and results obtained through studies of the top quark at the Tevatron.

THE "TOP PRIORITY" AT THE LHC

2008 ◽  
Vol 23 (25) ◽  
pp. 4107-4124 ◽  
Author(s):  
TAO HAN
Keyword(s):  
Elementary Particle ◽  
Top Quark ◽  
Hadron Collider ◽  
Top Quarks ◽  
New Physics ◽  
Great Accuracy ◽  
Electroweak Symmetry Breaking ◽  
Electroweak Symmetry ◽  
High Luminosity ◽  
The Standard Model

The LHC (Large Hadron Collider) will be a top-quark factory. With 80 million pairs of top quarks and an additional 34 million single tops produced annually at the designed high luminosity, the properties of this particle will be studied to a great accuracy. The fact that the top quark is the heaviest elementary particle in the Standard Model with a mass right at the electroweak scale makes it tempting to contemplate its role in electroweak symmetry breaking, as well as its potential as a window to unknown new physics at the TeV scale. We summarize the expectations for top-quark physics at the LHC, and outline new physics scenarios in which the top quark is crucially involved.

scholarly journals Probing Higgs boson CP properties with tt̄H at the LHC and the 100 TeV pp collider

2015 ◽  
Vol 30 (25) ◽  
pp. 1550156 ◽  
Author(s):  
Xiao-Gang He ◽  
Guan-Nan Li ◽  
Ya-Juan Zheng
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Top Quark ◽  
New Physics ◽  
Final States ◽  
Discrimination Power ◽  
Text Production ◽  
Wide Range ◽  
The Standard Model ◽  
The Ideal

The Higgs boson [Formula: see text] has the largest coupling to the top quark [Formula: see text] among the standard model (SM) fermions. This is one of the ideal places to investigate new physics beyond SM. In this work, we study the potential of determining Higgs boson [Formula: see text] properties at the LHC and future 33 TeV and 100 TeV [Formula: see text] colliders by analyzing various operators formed from final states variables in [Formula: see text] production. The discrimination power from SM coupling is obtained with Higgs boson reconstructed from [Formula: see text] and [Formula: see text]. We find that [Formula: see text] process can provide more than [Formula: see text] discrimination power with [Formula: see text] integrated luminosity in a wide range of allowed Higgs to top couplings for the LHC, the 33 TeV and 100 TeV colliders. For [Formula: see text] the discrimination power will be below [Formula: see text] at the LHC, while for 33 TeV and 100 TeV colliders, more than [Formula: see text] sensitivity can be reached.

scholarly journals The present and future of four top operators

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Giovanni Banelli ◽  
Ennio Salvioni ◽  
Javi Serra ◽  
Tobias Theil ◽  
Andreas Weiler
Keyword(s):  
Top Quark ◽  
High Energy ◽  
New Physics ◽  
Effective Field ◽  
Proton Proton ◽  
Strongly Coupled ◽  
Composite Higgs ◽  
Electron Positron ◽  
Energy Frontier ◽  
The Impact

Abstract We study the phenomenology of a strongly-interacting top quark at future hadron and lepton colliders, showing that the characteristic four-top contact operators give rise to the most significant effects. We demonstrate the extraordinary potential of a 100 TeV proton-proton collider to directly test such non-standard interactions in four-top production, a process that we thoroughly analyze in the same-sign dilepton and trilepton channels, and explore in the fully hadronic channel. Furthermore, high-energy electron-positron colliders, such as CLIC or the ILC, are shown to exhibit an indirect yet remarkable sensitivity to four-top operators, since these constitute, via renormalization group evolution, the leading new-physics deformations in top-quark pair production. We investigate the impact of our results on the parameter space of composite Higgs models with a strongly-coupled (right-handed) top quark, finding that four-top probes provide the best sensitivity on the compositeness scale at the future energy frontier. In addition, we investigate mild yet persisting LHC excesses in multilepton plus jets final states, showing that they can be consistently described in the effective field theory of such a new-physics scenario.

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