New flavor physics in di- and trilepton events from single-top production at the LHC and beyond

Journal Article · Fri Apr 30 00:00:00 EDT 2021 · Physical Review D

DOI:https://doi.org/10.1103/PhysRevD.103.075031· OSTI ID:1781143

Afik, Yoav ; Bar-Shalom, Shaouly; Soni, Amarjit; Wudka, Jose

The associated production of a single-top with opposite-sign same-flavor (OSSF) dileptons, $pp\to t{\ell }^{+}{\ell }^{-}$ and $pp\to t{\ell }^{+}{\ell }^{-}+j$ ( $j=\mathrm{light}\mathrm{jet}$), can lead to striking trilepton $pp\to {\ell }^{\text{'}}{\ell }^{+}{\ell }^{-}+X$ and dilepton $pp\to {\ell }^{+}{\ell }^{-}+j_b+X$ ( $j_b=b\text{-}\mathrm{jet}$) events at the LHC, after the top decays. Although these rather generic multilepton signals are flavor-blind, they can be generated by new 4-Fermi flavor changing (FC) $u_{i}t\ell \ell$ scalar, vector and tensor interactions ( $u_i\epsilon u$, $c$), which we study in this paper; we match the FC $u_{i}t\ell \ell$ 4-Fermi terms to the SMEFT operators and also to different types of FC underlying heavy physics. The main backgrounds to these di- and trilepton signals arise from $t\overline{t}$, $Z+\text{jets}$ and $VV$ ( $V=W$, $Z$) production, but they can be essentially eliminated with a sufficiently high invariant mass selection on the OSSF dileptons, $m_{{\ell }^{+}{\ell }^{-}}^{\mathsf{min}}\left(\mathrm{OSSF}\right)\gtrsim 1\mathrm{TeV}$; the use of $b$-tagging as an additional selection in the dilepton final state case also proves very useful. We find, for example, that the expected 95% CL bounds on the scale of a tensor(vector) $ut\mu \mu$ interaction, with the current $~140{\mathrm{fb}}^{-1}$ of LHC data, are $\mathrm{\Lambda }\lesssim 5\left(3.2\right)\mathrm{TeV}$ or $\mathrm{\Lambda }\lesssim 4.1\left(2.7\right)\mathrm{TeV}$, if analyzed via the dimuon ${\mu }^{+}{\mu }^{-}+j_b$ signal or the $e{\mu }^{+}{\mu }^{-}$ trilepton one, respectively. The expected reach at the HL-LHC with $3000{\mathrm{fb}}^{-1}$ of data is $\mathrm{\Lambda }\lesssim 7.1\left(4.7\right)\mathrm{TeV}$ and $\mathrm{\Lambda }\lesssim 2.4\left(1.5\right)\mathrm{TeV}$ for the corresponding $ut\mu \mu$ and $ct\mu \mu$ operators. This should be compared to the current bounds of $\mathrm{\Lambda }\lesssim \mathcal{O}\left(1\right)\mathrm{TeV}$ on both the $ut\ell \ell$ and $ct\ell \ell$ operators from LEP2 and from $pp\to t\overline{t}$ followed by $t\to {\ell }^{+}{\ell }^{-}j$. We also study the potential sensitivity at future 27 TeV and 100 TeV high-energy LHC successors, which, for the $ut\ell \ell$ operators, can reach $\mathrm{\Lambda }~10–40\mathrm{TeV}$. We furthermore discuss the possible implications of this class of FC 4-Fermi effective interactions on lepton nonuniversality tests at the LHC.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP)
• Grant/Contract Number: SC0012704
• OSTI ID: 1781143
• Alternate ID(s): OSTI ID: 1797359
• Report Number(s): BNL-221661-2021-JAAM; PRVDAQ; 075031
• Journal Information: Physical Review D, Journal Name: Physical Review D Vol. 103 Journal Issue: 7; ISSN 2470-0010
• Publisher: American Physical Society
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
effective field theory
higher-dimensional field theories
particle interactions
particle production