Lovre Pavičić, "Minimal scalar leptoquark model for RD(∗)"

jeudi 14 nov. 2024, 11:00 → 12:00 Europe/Paris

210/1-114 - Salle des Séminaires (IJCLab)

 Motivated by the long-standing discrepancy in lepton flavor universality ratios $R_D$ and $R_{D^{\ast }}$ we assess the status of scalar leptoquark states $R_2$, ${\tilde{R}}_2$ and $S_1$ which can in principle provide a desired enhancement of $\mathcal{B}(B\to D^{(\ast )}\tau \nu )$ in a minimal setup with two Yukawa couplings only. We consider unavoidable low-energy constraints, $Z$-pole measurements as well as high-$p_T$ constraints. After setting mass of each leptoquark to $1.5$ TeV we find that of all considered states only $S_1$ leptoquark, coupled to both chiralities of leptons and quarks, is still a completely viable solution. On the other hand, the scenario with $R_2$ is in growing tension with $\mathrm{\Gamma }(Z\to \tau \tau )$ and with the LHC constraints on the di-tau tails at high-$p_T$ while the ${\tilde{R}}_2$ scenario is in tension with the $\mathcal{B}(B\to K^{(\ast )}\nu \nu )$ observable. We comment on the future experimental tests of $S_1$ scenario. Furthermore, a scenario of the $S_1$ leptoquark coupled exclusively to right-handed SM fermions and a right-handed neutrino $N_R$ is also investigated as a potential solution for the $R_{D^{(\ast )}}$ with possible effects also in $\mathcal{B}(B\to K^{(\ast )}\nu \nu )$.

Orsay2024Pavicic.pdf