Phenomenology of TeV-scale scalar leptoquarks in the EFT

Journal Article · Mon Sep 16 00:00:00 EDT 2019 · Physical Review D

DOI:https://doi.org/10.1103/PhysRevD.100.055020· OSTI ID:1562168

Bar-Shalom, Shaouly; Cohen, Jonathan; Soni, Amarjit; Wudka, Jose

We examine new aspects of leptoquark (LQ) phenomenology using effective field theory (EFT). We construct a complete set of leading effective operators involving SU(2) singlets scalar LQ and the Standard Model fields up to dimension six. We show that, while the renormalizable LQ-lepton-quark interaction Lagrangian can address the persistent hints for physics beyond the Standard Model in the B-decays $$\bar{B}$$ → $$D^{(*)}$$$$_{τ{\bar{v}}}$$ → $$\bar{B}$$ → $$\bar{K}$$ $$\ell^{+}\ell^{-}$$ and in the measured anomalous magnetic moment of the muon, the LQ higher dimensional effective operators may lead to new interesting effects associated with lepton number violation. These include the generation of one-loop and two-loops sub-eV Majorana neutrino masses, mediation of neutrinoless $$\textbf{double-}β$$ decay and novel LQ collider signals. For the latter, we focus on third generation LQ ($$Φ_3$$) in a framework with an approximate $$Z_3$$ generation symmetry and show that one class of the dimension five LQ operators may give rise to a striking asymmetric same-charge $$Φ_3Φ_3$$ pair-production signal, which leads to low background same-sign leptons signals at the LHC. For example, with $$M_{Φ_3} ~ 1 TeV$$ and a new physics scale of $Λ ~ 5 TeV$, we expect at the 13 TeV LHC with an integrated luminosity of 300 fb^-1, about 5000 positively charged $τ^+τ^+$ events via $$pp → Φ_3Φ_3 → τ^+ τ^+ + 2 · j_b$$ ($$j_b = b-jet$$), about 500 negatively charged $τ^-τ^-$ events with a signature $$pp → Φ_3Φ_3 → τ^-τ^- + 4 · j + 2 · j_b$$ ($$j$$ = light jet) and about 50 positively charged $ℓ^+ ℓ^+$ events via $$pp → ℓ^+ ℓ^+ + 2 · j_ b +$$ $$\not{E}_T$$ for any of the three charged leptons, $ℓ^+ ℓ^+ = e^+ e^+, μ^+ μ^+, τ^+ τ^+$. It is interesting to note that, in the LQ EFT framework, the expected same-sign lepton signals have a rate which is several times larger than the QCD LQ-mediated opposite-sign leptons signals, $$gg, {\bar{qq}} → Φ_3Φ^*_3$$ → $ℓ^+ℓ^- + X$. We also consider the same-sign charged lepton signals in the LQ EFT framework at higher energy hadron colliders such as a 27 TeV HE-LHC and a 100 TeV FCC-hh.

• Research Organization: Brookhaven National Lab. (BNL), Upton, NY (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP)
• Grant/Contract Number: SC0012704
• OSTI ID: 1562168
• Alternate ID(s): OSTI ID: 1569539
• Report Number(s): BNL-212189-2019-JAAM; PRVDAQ; 055020
• Journal Information: Physical Review D, Journal Name: Physical Review D Vol. 100 Journal Issue: 5; ISSN 2470-0010
• Publisher: American Physical Society
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
phenomenology
TeV
leptoquark
EFT
scalar
lepton