Multi-lepton probes of new physics and lepton-universality in top-quark interactions

Abstract

We explore the sensitivity to new physics (NP) in the associated production of top-quarks with leptons $pp\to t\bar{t}{\ell }^{+}{\ell }^{-}$, which leads to the multi-leptons signals $pp\to n\ell +\mathtt{jets}+/E_T$, where $n=2,3,4$. The NP is parameterized via 4-Fermi effective $t\bar{t}{\ell }^{+}{\ell }^{-}$ contact interactions of various types, which are generated by multi-TeV heavy scalar, vector or tensor exchanges in $t\bar{t}\to {\ell }^{+}{\ell }^{-}$; we focus on the case of $\ell =e,\mu$. We match the 4-Fermi $tt\ell \ell$ terms to the SMEFT operators and also give examples of specific underlying heavy physics that can generate such terms. Analysis of the SM signals and corresponding backgrounds shows that the di-lepton and tri-lepton channels are much better probes of the effective $t\bar{t}{\ell }^{+}{\ell }^{-}$ 4-Fermi terms than the four-lepton one at the 13 TeV LHC. Therefore, the best sensitivity is obtained in the di- and tri-lepton channels, for which the dominant background $pp\to t\bar{t}$ and $pp\to WZ$, respectively, can be essentially eliminated after applying the $2\ell$ and $3\ell$ selections and a sufficiently high invariant mass selection for the opposite sign same flavor (OSSF) lepton-pair. We explore two cases: lepton flavor universal (LFU) NP where the $ttee$ and $tt\mu \mu$ contact interactions are of same size and LFU violating (LFUV) NP, where the scale of the $tt\mu \mu$ terms is assumed to be much lower. We show that in both cases it is possible to obtain new 95\% CL bounds on the scale of the $tt\ell \ell$ contact interactions at the level $\Lambda \gtrsim 2-3$ TeV, which are considerably tighter than the current bounds on these 4-Fermi terms.

arXiv comment18 pages, 6 figures, 8 tables. arXiv admin note: substantial text overlap with arXiv:2101.05286

References in corpus (82)

• FastJet user manual
• DELPHES 3, A modular framework for fast simulation of a generic collider experiment
• FeynRules 2.0 - A complete toolbox for tree-level phenomenology
• Dispelling the N^3 myth for the Kt jet-finder
• Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm
• Test of lepton universality using $B^{+}\to K^{+}{\ell }^{+}{\ell }^{-}$ decays
• Evidence for an excess of B -> D(*) Tau Nu decays
• Measurement of an Excess of B -> D(*) Tau Nu Decays and Implications for Charged Higgs Bosons
• Measurement of the branching ratio of $\bar{B}\to D^{(\ast )}{\tau }^{-}{\bar{\nu }}_{\tau }$ relative to $\bar{B}\to D^{(\ast )}{\ell }^{-}{\bar{\nu }}_{\ell }$ decays with hadronic tagging at Belle
• Physics of leptoquarks in precision experiments and at particle colliders
• Measurement of the ratio of branching fractions $\mathcal{B}({\overline{B}}^0\to D^{\ast +}{\tau }^{-}{\overline{\nu }}_{\tau })/\mathcal{B}({\overline{B}}^0\to D^{\ast +}{\mu }^{-}{\overline{\nu }}_{\mu })$
• The Standard Model as an Effective Field Theory
• One Leptoquark to Rule Them All: A Minimal Explanation for $R_{D^{(\ast )}}$, $R_K$ and $(g-2{)}_{\mu }$
• Measurement of the $\tau$ lepton polarization and $R(D^{\ast })$ in the decay $\bar{B}\to D^{\ast }{\tau }^{-}{\bar{\nu }}_{\tau }$
• Flavor Structure of Warped Extra Dimension Models
• Search for lepton-universality violation in $B^{+}\to K^{+}{\ell }^{+}{\ell }^{-}$ decays
• Anomalies in $B$-decays and $U(2)$ flavour symmetry
• Testing leptoquark models in $\bar{B}\to D^{(\ast )}\tau \bar{\nu }$
• Measurement of the ratio of the $B^0\to D^{\ast -}{\tau }^{+}{\nu }_{\tau }$ and $B^0\to D^{\ast -}{\mu }^{+}{\nu }_{\mu }$ branching fractions using three-prong $\tau$-lepton decays
• Single Top Production as a Window to Physics Beyond the Standard Model
• Test of Lepton Flavor Universality by the measurement of the $B^0\to D^{\ast -}{\tau }^{+}{\nu }_{\tau }$ branching fraction using three-prong $\tau$ decays
• Confronting lepton flavor universality violation in B decays with high-$p_T$ tau lepton searches at LHC
• Patterns of Deviation from the Standard Model
• Lepton Flavor Violation in B Decays?
• Gauge leptoquark as the origin of B-physics anomalies
• New physics in the weak interaction of $\bar{B}\to D^{(\ast )}\tau \bar{\nu }$
• Importance of Loop Effects in Explaining the Accumulated Evidence for New Physics in B Decays with a Vector Leptoquark
• High-$p_T$ dilepton tails and flavour physics
• Review of Lepton Universality tests in B decays
• A new evaluation of the t->cH decay width in the standard model
• $R_{D^{(\ast )}}$ anomaly: A possible hint for natural supersymmetry with $R$-parity violation
• Collider Signals of Top Quark Flavor Violation from a Warped Extra Dimension
• CP Violation in Top Physics
• A global approach to top-quark flavor-changing interactions
• New Physics in $b\to s{\ell }^{+}{\ell }^{-}$ confronts new data on Lepton Universality
• Effective four-fermion operators in top physics: a roadmap
• The Bases of Effective Field Theories
• Probing flavor changing top-charm-scalar interactions in $e^{+}{e}^{-}$ collisions
• Automated Parton-Shower Variations in Pythia 8
• Excesses of muon $g-2$, $R_{D^{(\ast )}}$, and $R_K$ in a leptoquark model
• Scalar leptoquarks and the rare B meson decays
• Left-Right SU(4) Vector Leptoquark Model for Flavor Anomalies
• Top-Quark Decay Via Flavor-Changing Neutral Currents at Hadron Colliders
• High-pT Signatures in Vector-Leptoquark Models
• Search for production of four top quarks in final states with same-sign or multiple leptons in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Lepton flavor universality violation without new sources of quark flavor violation
• When the Higgs meets the Top: Search for t --> ch^0 at the LHC
• Associated production of Higgs and single top at hadron colliders
• Measurement of the Higgs boson production rate in association with top quarks in final states with electrons, muons, and hadronically decaying tau leptons at $\sqrt{s}=$ 13 TeV
• Evidence for $t\bar{t}t\bar{t}$ production in the multilepton final state in proton-proton collisions at $\sqrt{s}$=13 TeV with the ATLAS detector
• Anomalies in Bottom from new physics in Top
• Addressing $R_{D^{(\ast )}}$, $R_{K^{(\ast )}}$, muon $g-2$ and ANITA anomalies in a minimal $R$-parity violating supersymmetric framework
• Combined explanations of $(g-2{)}_{\mu }$, $R_{D^{(\ast )}}$, $R_{K^{(\ast )}}$ anomalies in a two-loop radiative neutrino mass model
• Single Top Production at Next-to-Leading Order in the Standard Model Effective Field Theory
• $R_2$ as a single leptoquark solution to $R_{D^{(\ast )}}$ and $R_{K^{(\ast )}}$
• SMEFT and the Drell-Yan Process at High Energy
• Searching for Leptoquarks at IceCube and the LHC
• Top and Beauty synergies in SMEFT-fits at present and future colliders
• Unified explanation of flavor anomalies, radiative neutrino mass and ANITA anomalous events in a vector leptoquark model
• Scalar FCNC and rare top decays in a two Higgs doublet model "for the top"
• Explanation of $B\to K^{(\ast )}{\ell }^{+}{\ell }^{-}$ and muon $g-2$, and implications at the LHC
• Zt and γt production via top flavour-changing neutral couplings at the Fermilab Tevatron
• Top-Charm Associated Production at High Energy e^+e^- Colliders in Standard Model
• Flavor changing single top quark production channels at e^+e^- colliders in the effective Lagrangian description
• Leptoquark Option for $B$-meson Anomalies and Leptonic Signatures
• Single top quark production as a probe of anomalous $tq\gamma$ and $tqZ$ couplings at the FCC-ee
• Top quark decay at next-to-leading order in the Standard Model Effective Field Theory
• Probing top anomalous couplings at the LHC with trilepton signatures in the single top mode
• Combined effects of strong and electroweak FCNC effective operators in top quark physics at the LHC
• Flavor Changing Neutral Higgs Couplings and Top-Charm Production at Next Linear Collider
• Lepton Flavour Violating top decays at the LHC
• Searching for New Physics with $b\bar{b}{\ell }^{+}{\ell }^{-}$ Contact Interactions
• Next-to-leading order QCD corrections to $tZ$ associated production via the flavor-changing neutral-current couplings at hadron colliders
• Probing Anomalous FCNC Top-Higgs Yukawa Couplings at the Large Hadron Electron Collider
• Higher-order corrections for $tZ$ production via anomalous couplings
• Searches for top-Higgs FCNC couplings via the Whj signal with $h\to \gamma \gamma$ at the LHC
• Searches for anomalous $tqZ$ couplings from the trilepton signal of $tZ$ associated production at the 14 TeV LHC
• Search for anomalous couplings via single top quark production in association with a photon at LHC
• Searches for the FCNC couplings from top-Higgs associated production signal with $h\to \gamma \gamma$ at the LHC
• Effective Field Theory in the top sector: do multijets help?
• Search for new phenomena in final states with two leptons and one or no $b$-tagged jets at $\sqrt{s}=13$ TeV using the ATLAS detector
• High $p_T$ correlated tests of lepton universality in lepton(s) + jet(s) processes; an EFT analysis

Cited by in corpus (4)

• NLO QCD corrections to full off-shell production of $t\bar{t}Z$ including leptonic decays
• Marriage between neutrino mass and flavor anomalies
• Probing the muon (g-2) anomaly at the LHC in final states with two muons and two taus
• Generic tests of CP-violation in high-$p_{\text{T}}$ multi-lepton signals at the LHC and beyond