90% CL upper limit in axion-like particle coupling to SM fermions at UV scale Lambda=1TeV vs mass parameter space for di-lepton final states.

90% CL upper limit in axion-like particle coupling to SM gluons at UV scale Lambda=1TeV vs mass parameter space for hadronic final states.

Number of expected $a \to K^+K^-\pi^0$ events for BR = 1 in the plane (mass, width) after full selection, for production in B meson decays assuming production coupling $C_{bs}/\Lambda=1\,\mathrm{GeV}^{-1}$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to \pi^+\pi^-\eta$ events for BR = 1 in the plane (mass, width) after full selection, for production in B meson decays assuming production coupling $C_{bs}/\Lambda=1\,\mathrm{GeV}^{-1}$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to \pi^+\pi^-\gamma$ events for BR = 1 in the plane (mass, width) after full selection, for production in B meson decays assuming production coupling $C_{bs}/\Lambda=1\,\mathrm{GeV}^{-1}$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to \pi^+\pi^-\pi^0$ events for BR = 1 in the plane (mass, width) after full selection, for production in B meson decays assuming production coupling $C_{bs}/\Lambda=1\,\mathrm{GeV}^{-1}$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to \pi^+\pi^-\pi^0\pi^0$ events for BR = 1 in the plane (mass, width) after full selection, for production in B meson decays assuming production coupling $C_{bs}/\Lambda=1\,\mathrm{GeV}^{-1}$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to e^+e^-$ events for BR = 1 in the plane (mass, width) after full selection, for production in mixing with $\pi^0$ assuming production coupling $\theta_{\pi^0} = 1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to \mu^+\mu^-$ events for BR = 1 in the plane (mass, width) after full selection, for production in mixing with $\pi^0$ assuming production coupling $\theta_{\pi^0} = 1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to K^+K^-\pi^0$ events for BR = 1 in the plane (mass, width) after full selection, for production in mixing with $\pi^0$ assuming production coupling $\theta_{\pi^0} = 1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to \pi^+\pi^-\eta$ events for BR = 1 in the plane (mass, width) after full selection, for production in mixing with $\pi^0$ assuming production coupling $\theta_{\pi^0} = 1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to \pi^+\pi^-\gamma$ events for BR = 1 in the plane (mass, width) after full selection, for production in mixing with $\pi^0$ assuming production coupling $\theta_{\pi^0} = 1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to \pi^+\pi^-\pi^0$ events for BR = 1 in the plane (mass, width) after full selection, for production in mixing with $\pi^0$ assuming production coupling $\theta_{\pi^0} = 1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to \pi^+\pi^-\pi^0\pi^0$ events for BR = 1 in the plane (mass, width) after full selection, for production in mixing with $\pi^0$ assuming production coupling $\theta_{\pi^0} = 1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to e^+e^-$ events for BR = 1 in the plane (mass, width) after full selection, for production in mixing with $\eta$ assuming production coupling $\theta_{\eta} = 1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to \mu^+\mu^-$ events for BR = 1 in the plane (mass, width) after full selection, for production in mixing with $\eta$ assuming production coupling $\theta_{\eta} = 1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to K^+K^-\pi^0$ events for BR = 1 in the plane (mass, width) after full selection, for production in mixing with $\eta$ assuming production coupling $\theta_{\eta} = 1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to \pi^+\pi^-\eta$ events for BR = 1 in the plane (mass, width) after full selection, for production in mixing with $\eta$ assuming production coupling $\theta_{\eta} = 1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to \pi^+\pi^-\gamma$ events for BR = 1 in the plane (mass, width) after full selection, for production in mixing with $\eta$ assuming production coupling $\theta_{\eta} = 1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to \pi^+\pi^-\pi^0$ events for BR = 1 in the plane (mass, width) after full selection, for production in mixing with $\eta$ assuming production coupling $\theta_{\eta} = 1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to \pi^+\pi^-\pi^0\pi^0$ events for BR = 1 in the plane (mass, width) after full selection, for production in mixing with $\eta$ assuming production coupling $\theta_{\eta} = 1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to e^+e^-$ events for BR = 1 in the plane (mass, width) after full selection, for production in mixing with $\eta^\prime$ assuming production coupling $\theta_{\eta^\prime} = 1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to \mu^+\mu^-$ events for BR = 1 in the plane (mass, width) after full selection, for production in mixing with $\eta^\prime$ assuming production coupling $\theta_{\eta^\prime} = 1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to K^+K^-\pi^0$ events for BR = 1 in the plane (mass, width) after full selection, for production in mixing with $\eta^\prime$ assuming production coupling $\theta_{\eta^\prime} = 1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to \pi^+\pi^-\eta$ events for BR = 1 in the plane (mass, width) after full selection, for production in mixing with $\eta^\prime$ assuming production coupling $\theta_{\eta^\prime} = 1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to \pi^+\pi^-\gamma$ events for BR = 1 in the plane (mass, width) after full selection, for production in mixing with $\eta^\prime$ assuming production coupling $\theta_{\eta^\prime} = 1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to \pi^+\pi^-\pi^0$ events for BR = 1 in the plane (mass, width) after full selection, for production in mixing with $\eta^\prime$ assuming production coupling $\theta_{\eta^\prime} = 1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to \pi^+\pi^-\pi^0\pi^0$ events for BR = 1 in the plane (mass, width) after full selection, for production in mixing with $\eta^\prime$ assuming production coupling $\theta_{\eta^\prime} = 1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to e^+e^-$ events for BR = 1 in the plane (mass, width) after full selection, for Primakoff production assuming production coupling $C_{\gamma\gamma}/\Lambda=1\,\mathrm{GeV}^{-1}$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to \mu^+\mu^-$ events for BR = 1 in the plane (mass, width) after full selection, for Primakoff production assuming production coupling $C_{\gamma\gamma}/\Lambda=1\,\mathrm{GeV}^{-1}$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to K^+K^-\pi^0$ events for BR = 1 in the plane (mass, width) after full selection, for Primakoff production assuming production coupling $C_{\gamma\gamma}/\Lambda=1\,\mathrm{GeV}^{-1}$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to \pi^+\pi^-\eta$ events for BR = 1 in the plane (mass, width) after full selection, for Primakoff production assuming production coupling $C_{\gamma\gamma}/\Lambda=1\,\mathrm{GeV}^{-1}$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to \pi^+\pi^-\gamma$ events for BR = 1 in the plane (mass, width) after full selection, for Primakoff production assuming production coupling $C_{\gamma\gamma}/\Lambda=1\,\mathrm{GeV}^{-1}$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to \pi^+\pi^-\pi^0$ events for BR = 1 in the plane (mass, width) after full selection, for Primakoff production assuming production coupling $C_{\gamma\gamma}/\Lambda=1\,\mathrm{GeV}^{-1}$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $a \to \pi^+\pi^-\pi^0\pi^0$ events for BR = 1 in the plane (mass, width) after full selection, for Primakoff production assuming production coupling $C_{\gamma\gamma}/\Lambda=1\,\mathrm{GeV}^{-1}$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $A^\prime \to e^+e^-$ events for BR = 1 in the plane (mass, width) after full selection, for Bremsstrahlung production assuming production coupling $\varepsilon=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $A^\prime \to \mu^+\mu^-$ events for BR = 1 in the plane (mass, width) after full selection, for Bremsstrahlung production assuming production coupling $\varepsilon=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $A^\prime \to K^+K^-$ events for BR = 1 in the plane (mass, width) after full selection, for Bremsstrahlung production assuming production coupling $\varepsilon=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $A^\prime \to K^+K^-\pi^0$ events for BR = 1 in the plane (mass, width) after full selection, for Bremsstrahlung production assuming production coupling $\varepsilon=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $A^\prime \to \pi^+\pi^-$ events for BR = 1 in the plane (mass, width) after full selection, for Bremsstrahlung production assuming production coupling $\varepsilon=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $A^\prime \to \pi^+\pi^-\pi^0$ events for BR = 1 in the plane (mass, width) after full selection, for Bremsstrahlung production assuming production coupling $\varepsilon=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $A^\prime \to \pi^+\pi^-\pi^0\pi^0$ events for BR = 1 in the plane (mass, width) after full selection, for Bremsstrahlung production assuming production coupling $\varepsilon=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $A^\prime \to e^+e^-$ events for BR = 1 in the plane (mass, width) after full selection, for mixing production assuming production coupling $\varepsilon=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $A^\prime \to \mu^+\mu^-$ events for BR = 1 in the plane (mass, width) after full selection, for mixing production assuming production coupling $\varepsilon=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $A^\prime \to K^+K^-$ events for BR = 1 in the plane (mass, width) after full selection, for mixing production assuming production coupling $\varepsilon=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $A^\prime \to K^+K^-\pi^0$ events for BR = 1 in the plane (mass, width) after full selection, for mixing production assuming production coupling $\varepsilon=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $A^\prime \to \pi^+\pi^-$ events for BR = 1 in the plane (mass, width) after full selection, for mixing production assuming production coupling $\varepsilon=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $A^\prime \to \pi^+\pi^-\pi^0$ events for BR = 1 in the plane (mass, width) after full selection, for mixing production assuming production coupling $\varepsilon=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $A^\prime \to \pi^+\pi^-\pi^0\pi^0$ events for BR = 1 in the plane (mass, width) after full selection, for mixing production assuming production coupling $\varepsilon=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $A^\prime \to e^+e^-$ events for BR = 1 in the plane (mass, width) after full selection, for production in light meson decays assuming production coupling $\varepsilon=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $A^\prime \to \mu^+\mu^-$ events for BR = 1 in the plane (mass, width) after full selection, for production in light meson decays assuming production coupling $\varepsilon=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $A^\prime \to \pi^+\pi^-$ events for BR = 1 in the plane (mass, width) after full selection, for production in light meson decays assuming production coupling $\varepsilon=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $A^\prime \to \pi^+\pi^-\pi^0$ events for BR = 1 in the plane (mass, width) after full selection, for production in light meson decays assuming production coupling $\varepsilon=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $A^\prime \to \pi^+\pi^-\pi^0\pi^0$ events for BR = 1 in the plane (mass, width) after full selection, for production in light meson decays assuming production coupling $\varepsilon=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $S \to e^+e^-$ events for BR = 1 in the plane (mass, width) after full selection, for Bremsstrahlung production assuming production coupling $\mathrm{sin}^2\theta=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $S \to \mu^+\mu^-$ events for BR = 1 in the plane (mass, width) after full selection, for Bremsstrahlung production assuming production coupling $\mathrm{sin}^2\theta=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $S \to K^+K^-$ events for BR = 1 in the plane (mass, width) after full selection, for Bremsstrahlung production assuming production coupling $\mathrm{sin}^2\theta=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $S \to \pi^+\pi^-$ events for BR = 1 in the plane (mass, width) after full selection, for Bremsstrahlung production assuming production coupling $\mathrm{sin}^2\theta=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $S \to \pi^+\pi^-\pi^0\pi^0$ events for BR = 1 in the plane (mass, width) after full selection, for Bremsstrahlung production assuming production coupling $\mathrm{sin}^2\theta=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $S \to e^+e^-$ events for BR = 1 in the plane (mass, width) after full selection, for production in B meson decays assuming production coupling $\mathrm{sin}^2\theta=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $S \to \mu^+\mu^-$ events for BR = 1 in the plane (mass, width) after full selection, for production in B meson decays assuming production coupling $\mathrm{sin}^2\theta=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $S \to K^+K^-$ events for BR = 1 in the plane (mass, width) after full selection, for production in B meson decays assuming production coupling $\mathrm{sin}^2\theta=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Number of expected $S \to \pi^+\pi^-$ events for BR = 1 in the plane (mass, width) after full selection, for production in B meson decays assuming production coupling $\mathrm{sin}^2\theta=1$. Acceptance for particles that reach the FV and decay therein and mass resolution.

Background-only fit to the observed numbers of events (black points) as a function of the diphoton invariant mass $m_{\gamma\gamma}$.

Expected and observed 95% CL upper limits on the signal fiducial cross section $\sigma_{\textrm{fid}}$, assuming 100% branching ratio for ALP decay into two photons, as a function of the hypothetical ALP mass $m_{\textrm{X}}$. The 1$\sigma$ and 2$\sigma$ confidence intervals are shown by the coloured bands.

Expected and observed 95% CL upper limits on the the ALP coupling constant, assuming 100% branching ratio for ALP decay into two photons, as a function of the hypothetical ALP mass $m_{\textrm{X}}$. The 1$\sigma$ and 2$\sigma$ confidence intervals are shown by the coloured bands. Contours of the ALP natural width $\Gamma$ are illustrated by the smooth blue solid lines.

Fiducial region acceptance of signal events for coupling constant f$^{-1}=0.05$ TeV$^{-1}$. EL, SD, and DD stand for the exclusive, single-dissociative, and double-dissociative processes. The acceptances are parameterised as $p_0 + p^{i}_{1} e^{p_{2}^{i} m_{\textrm{X}}} + p_{3}^{i} e^{p_{4}^{i} m_{\textrm{X}}} $ , where $i$ specifies the process type, exclusive, single-dissociative, or double-dissociative.

Correction factors $A_{\textrm{X}}/A_{0}$ and $C_{\textrm{X}}$ for the exclusive signal events with ALP coupling constant f$^{-1}$=0.05 TeV$^{-1}$, where acceptance $A_{\textrm{X}}$ and efficiency $C_{\textrm{X}}$ are defined in arXiv:2102.13405. $A_{\textrm{X}}$/$A_{0}$ and $C_{\textrm{X}}$ are parameterised as $p_0 + p^{i}_{1} e^{p_{2}^{i} m_{\textrm{X}}} + p_{3}^{i} e^{p_{4}^{i} m_{\textrm{X}}}$, where $i$ specifies the process type.

Simulated ALP signal cutflow for $m_{\rm{X}}$=300 GeV and $m_{\rm{X}}$=1200 GeV. The yields are normalized to a luminosity of 14.6 fb$^{-1}$. Selections are applied for each side after the selection on acoplanarity. The union of the sets of selected events is taken finally.