Invariant mass $m_{\mu\mu}$ distributions in the $N_{\mathrm{b}} = 1$ category, shown together with the corresponding selected background functional forms used as input to the $discrete~profiling$ method when probing the $m_{\mathrm{Z'}}=500~\mathrm{GeV}$ hypothesis. The expected signal distribution for the LFU model described in Eq. (1), with couplings $|g_{\ell}| = |g_{\nu}| = |g_{\mathrm{b}}| = 0.03$ and $\delta_{\mathrm{bs}}=0$, is overlaid. The displayed mass range corresponds to the fit window used for this $m_{\mathrm{Z'}}$ hypothesis, which is $\pm 10\, \sigma_{\mathrm{mass}}$ around the probed $m_{\mathrm{Z'}}$ value. While the likelihood fits are performed on unbinned data, here we present the data in binned histograms with binning chosen to reflect the size of $\sigma_{\mathrm{mass}}$.

Invariant mass $m_{\mu\mu}$ distributions in the $N_{\mathrm{b}} \geq 2$ category, shown together with the corresponding selected background functional forms used as input to the $discrete~profiling$ method when probing the $m_{\mathrm{Z'}}=500~\mathrm{GeV}$ hypothesis. The expected signal distribution for the LFU model described in Eq. (1), with couplings $|g_{\ell}| = |g_{\nu}| = |g_{\mathrm{b}}| = 0.03$ and $\delta_{\mathrm{bs}}=0$, is overlaid. The displayed mass range corresponds to the fit window used for this $m_{\mathrm{Z'}}$ hypothesis, which is $\pm 10\, \sigma_{\mathrm{mass}}$ around the probed $m_{\mathrm{Z'}}$ value. While the likelihood fits are performed on unbinned data, here we present the data in binned histograms with binning chosen to reflect the size of $\sigma_{\mathrm{mass}}$.

Exclusion limits at $95\%$ CL on the number of selected BSM events with $N_{\mathrm{b}} \geq 1$ as functions of $m_{\mathrm{Z'}}$ for $f_{2\mathrm{b}}=0$. The quantity $f_{2\mathrm{b}}$ is the fraction of BSM events passing the analysis selection that have at least two $\mathrm{b}$ quark jets. The solid black (dashed red) curve represents the observed (median expected) exclusion. The inner green (outer yellow) band indicates the region containing $68~(95)\%$ of the distribution of limits expected under the background-only hypothesis.

Exclusion limits at $95\%$ CL on the number of selected BSM events with $N_{\mathrm{b}} \geq 1$ as functions of $m_{\mathrm{Z'}}$ for $f_{2\mathrm{b}}=0.25$. The quantity $f_{2\mathrm{b}}$ is the fraction of BSM events passing the analysis selection that have at least two $\mathrm{b}$ quark jets. The solid black (dashed red) curve represents the observed (median expected) exclusion. The inner green (outer yellow) band indicates the region containing $68~(95)\%$ of the distribution of limits expected under the background-only hypothesis.

Exclusion limits at $95\%$ CL on the number of selected BSM events with $N_{\mathrm{b}} \geq 1$ as functions of $m_{\mathrm{Z'}}$ for $f_{2\mathrm{b}}=0.75$. The quantity $f_{2\mathrm{b}}$ is the fraction of BSM events passing the analysis selection that have at least two $\mathrm{b}$ quark jets. The solid black (dashed red) curve represents the observed (median expected) exclusion. The inner green (outer yellow) band indicates the region containing $68~(95)\%$ of the distribution of limits expected under the background-only hypothesis.

Exclusion limits at $95\%$ CL on the number of selected BSM events with $N_{\mathrm{b}} \geq 1$ as functions of $m_{\mathrm{Z'}}$ for $f_{2\mathrm{b}}=1$. The quantity $f_{2\mathrm{b}}$ is the fraction of BSM events passing the analysis selection that have at least two $\mathrm{b}$ quark jets. The solid black (dashed red) curve represents the observed (median expected) exclusion. The inner green (outer yellow) band indicates the region containing $68~(95)\%$ of the distribution of limits expected under the background-only hypothesis.

Observed (solid) and median expected (dashed) exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $\delta_{\mathrm{bs}}=0$ and $|g_{\nu}|=|g_{\ell}|$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution, marked by the dotted curves. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Observed exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $\delta_{\mathrm{bs}}=0$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=350~\mathrm{GeV}$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Expected exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $\delta_{\mathrm{bs}}=0$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=350~\mathrm{GeV}$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $\delta_{\mathrm{bs}}=0$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=350~\mathrm{GeV}$. The coupling values are shown at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid.

Observed exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $\delta_{\mathrm{bs}}=0$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=500~\mathrm{GeV}$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Expected exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $\delta_{\mathrm{bs}}=0$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=500~\mathrm{GeV}$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $\delta_{\mathrm{bs}}=0$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=500~\mathrm{GeV}$. The coupling values are shown at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid.

Observed exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $\delta_{\mathrm{bs}}=0$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=700~\mathrm{GeV}$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Expected exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $\delta_{\mathrm{bs}}=0$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=700~\mathrm{GeV}$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $\delta_{\mathrm{bs}}=0$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=700~\mathrm{GeV}$. The coupling values are shown at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid.

Observed exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $\delta_{\mathrm{bs}}=0$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=1~\mathrm{TeV}$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Expected exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $\delta_{\mathrm{bs}}=0$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=1~\mathrm{TeV}$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $\delta_{\mathrm{bs}}=0$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=1~\mathrm{TeV}$. The coupling values are shown at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid.

Observed exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $\delta_{\mathrm{bs}}=0$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=1.5~\mathrm{TeV}$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Expected exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $\delta_{\mathrm{bs}}=0$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=1.5~\mathrm{TeV}$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $\delta_{\mathrm{bs}}=0$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=1.5~\mathrm{TeV}$. The coupling values are shown at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid.

Observed exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $\delta_{\mathrm{bs}}=0$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=2~\mathrm{TeV}$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Expected exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $\delta_{\mathrm{bs}}=0$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=2~\mathrm{TeV}$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $\delta_{\mathrm{bs}}=0$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=2~\mathrm{TeV}$. The coupling values are shown at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid.

Observed (solid) and median expected (dashed) exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $|\delta_{\mathrm{bs}}|=0.25$ and $|g_{\nu}|=|g_{\ell}|$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution, marked by the dotted curves. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Observed exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $|\delta_{\mathrm{bs}}|=0.25$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=350~\mathrm{GeV}$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Expected exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $|\delta_{\mathrm{bs}}|=0.25$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=350~\mathrm{GeV}$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $|\delta_{\mathrm{bs}}|=0.25$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=350~\mathrm{GeV}$. The coupling values are shown at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid.

Observed exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $|\delta_{\mathrm{bs}}|=0.25$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=500~\mathrm{GeV}$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Expected exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $|\delta_{\mathrm{bs}}|=0.25$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=500~\mathrm{GeV}$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $|\delta_{\mathrm{bs}}|=0.25$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=500~\mathrm{GeV}$. The coupling values are shown at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid.

Observed exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $|\delta_{\mathrm{bs}}|=0.25$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=700~\mathrm{GeV}$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Expected exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $|\delta_{\mathrm{bs}}|=0.25$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=700~\mathrm{GeV}$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $|\delta_{\mathrm{bs}}|=0.25$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=700~\mathrm{GeV}$. The coupling values are shown at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid.

Observed exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $|\delta_{\mathrm{bs}}|=0.25$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=1~\mathrm{TeV}$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Expected exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $|\delta_{\mathrm{bs}}|=0.25$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=1~\mathrm{TeV}$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $|\delta_{\mathrm{bs}}|=0.25$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=1~\mathrm{TeV}$. The coupling values are shown at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid.

Observed exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $|\delta_{\mathrm{bs}}|=0.25$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=1.5~\mathrm{TeV}$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Expected exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $|\delta_{\mathrm{bs}}|=0.25$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=1.5~\mathrm{TeV}$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $|\delta_{\mathrm{bs}}|=0.25$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=1.5~\mathrm{TeV}$. The coupling values are shown at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid.

Observed exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $|\delta_{\mathrm{bs}}|=0.25$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=2~\mathrm{TeV}$. The exclusion limits are given up to coupling values at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid. The enclosed regions are excluded.

Exclusion limits at $95\%$ CL in the $|g_{\mathrm{b}}|$--$|g_{\ell}|$ plane for the LFU model, with $|\delta_{\mathrm{bs}}|=0.25$ and $|g_{\nu}|=|g_{\ell}|$, for $m_{\mathrm{Z'}}=2~\mathrm{TeV}$. The coupling values are shown at which the $\mathrm{Z'}$ width is equal to half of the $\mu\mu$ invariant mass resolution. Beyond these coupling values, the narrow width approximation intrinsic to the search strategy is not considered valid.

Exclusion limits at $95\%$ CL in the $|\theta_{23}|$--$|g_{\mathrm{Z'}}|$ plane for the $B_{3}\!-\!L_{2}$ model from JHEP 04 (2023) 033, for $m_{\mathrm{Z'}}=500~\mathrm{GeV}$. The solid black (dashed red) curves represent the observed (median expected) exclusions. The dotted curves denote the coupling values at which the $\mathrm{Z'}$ width equals one half of the $\mu\mu$ invariant mass resolution. For larger values of the couplings, the narrow width approximation intrinsic to the search strategy is not considered valid. The region enclosed between the solid black (dashed red) and dotted curves is (expected to be) excluded. The dotted curve for $m_{\mathrm{Z'}}=500~\mathrm{GeV}$ lies beyond the displayed $|g_{\mathrm{Z'}}|$ range and is, therefore, not shown. The shaded blue area represents the region preferred from the global fit in JHEP 04 (2023) 033 at $95\%$ CL. The region above the green dash-dotted curve is incompatible at $95\%$ CL with the measurement of the mass difference between the mass eigenstates of the neutral $\mathrm{B}_\mathrm{s}$ mesons.

Observed exclusion limits at $95\%$ CL in the $|\theta_{23}|$--$|g_{\mathrm{Z'}}|$ plane for the $B_{3}\!-\!L_{2}$ model from JHEP 04 (2023) 033, for $m_{\mathrm{Z'}}=500~\mathrm{GeV}$.

Expected exclusion limits at $95\%$ CL in the $|\theta_{23}|$--$|g_{\mathrm{Z'}}|$ plane for the $B_{3}\!-\!L_{2}$ model from JHEP 04 (2023) 033, for $m_{\mathrm{Z'}}=500~\mathrm{GeV}$.

Exclusion limits at $95\%$ CL in the $|\theta_{23}|$--$|g_{\mathrm{Z'}}|$ plane for the $B_{3}\!-\!L_{2}$ model from JHEP 04 (2023) 033, for $m_{\mathrm{Z'}}=1~\mathrm{TeV}$. The solid black (dashed red) curves represent the observed (median expected) exclusions. The dotted curves denote the coupling values at which the $\mathrm{Z'}$ width equals one half of the $\mu\mu$ invariant mass resolution. For larger values of the couplings, the narrow width approximation intrinsic to the search strategy is not considered valid. The region enclosed between the solid black (dashed red) and dotted curves is (expected to be) excluded. The shaded blue area represents the region preferred from the global fit in JHEP 04 (2023) 033 at $95\%$ CL. The region above the green dash-dotted curve is incompatible at $95\%$ CL with the measurement of the mass difference between the mass eigenstates of the neutral $\mathrm{B}_\mathrm{s}$ mesons.

Observed exclusion limits at $95\%$ CL in the $|\theta_{23}|$--$|g_{\mathrm{Z'}}|$ plane for the $B_{3}\!-\!L_{2}$ model from JHEP 04 (2023) 033, for $m_{\mathrm{Z'}}=1~\mathrm{TeV}$.

Expected exclusion limits at $95\%$ CL in the $|\theta_{23}|$--$|g_{\mathrm{Z'}}|$ plane for the $B_{3}\!-\!L_{2}$ model from JHEP 04 (2023) 033, for $m_{\mathrm{Z'}}=1~\mathrm{TeV}$.

Exclusion limits at $95\%$ CL in the $|\theta_{23}|$--$|g_{\mathrm{Z'}}|$ plane for the $B_{3}\!-\!L_{2}$ model from JHEP 04 (2023) 033, for $m_{\mathrm{Z'}}=1~\mathrm{TeV}$. The coupling values are shown at which the $\mathrm{Z'}$ width equals one half of the $\mu\mu$ invariant mass resolution. For larger values of the couplings, the narrow width approximation intrinsic to the search strategy is not considered valid.

Exclusion limits at $95\%$ CL in the $|\theta_{23}|$--$|g_{\mathrm{Z'}}|$ plane for the $B_{3}\!-\!L_{2}$ model from JHEP 04 (2023) 033, for $m_{\mathrm{Z'}}=1.5~\mathrm{TeV}$. The solid black (dashed red) curves represent the observed (median expected) exclusions. The dotted curves denote the coupling values at which the $\mathrm{Z'}$ width equals one half of the $\mu\mu$ invariant mass resolution. For larger values of the couplings, the narrow width approximation intrinsic to the search strategy is not considered valid. The region enclosed between the solid black (dashed red) and dotted curves is (expected to be) excluded. The shaded blue area represents the region preferred from the global fit in JHEP 04 (2023) 033 at $95\%$ CL. The region above the green dash-dotted curve is incompatible at $95\%$ CL with the measurement of the mass difference between the mass eigenstates of the neutral $\mathrm{B}_\mathrm{s}$ mesons.

Observed exclusion limits at $95\%$ CL in the $|\theta_{23}|$--$|g_{\mathrm{Z'}}|$ plane for the $B_{3}\!-\!L_{2}$ model from JHEP 04 (2023) 033, for $m_{\mathrm{Z'}}=1.5~\mathrm{TeV}$.

Expected exclusion limits at $95\%$ CL in the $|\theta_{23}|$--$|g_{\mathrm{Z'}}|$ plane for the $B_{3}\!-\!L_{2}$ model from JHEP 04 (2023) 033, for $m_{\mathrm{Z'}}=1.5~\mathrm{TeV}$.

Exclusion limits at $95\%$ CL in the $|\theta_{23}|$--$|g_{\mathrm{Z'}}|$ plane for the $B_{3}\!-\!L_{2}$ model from JHEP 04 (2023) 033, for $m_{\mathrm{Z'}}=1.5~\mathrm{TeV}$. The coupling values are shown at which the $\mathrm{Z'}$ width equals one half of the $\mu\mu$ invariant mass resolution. For larger values of the couplings, the narrow width approximation intrinsic to the search strategy is not considered valid.

Exclusion limits at $95\%$ CL in the $|\theta_{23}|$--$|g_{\mathrm{Z'}}|$ plane for the $B_{3}\!-\!L_{2}$ model from JHEP 04 (2023) 033, for $m_{\mathrm{Z'}}=2~\mathrm{TeV}$. The solid black (dashed red) curves represent the observed (median expected) exclusions. The dotted curves denote the coupling values at which the $\mathrm{Z'}$ width equals one half of the $\mu\mu$ invariant mass resolution. For larger values of the couplings, the narrow width approximation intrinsic to the search strategy is not considered valid. The region enclosed between the solid black (dashed red) and dotted curves is (expected to be) excluded. The shaded blue area represents the region preferred from the global fit in JHEP 04 (2023) 033 at $95\%$ CL. The region above the green dash-dotted curve is incompatible at $95\%$ CL with the measurement of the mass difference between the mass eigenstates of the neutral $\mathrm{B}_\mathrm{s}$ mesons.

Observed exclusion limits at $95\%$ CL in the $|\theta_{23}|$--$|g_{\mathrm{Z'}}|$ plane for the $B_{3}\!-\!L_{2}$ model from JHEP 04 (2023) 033, for $m_{\mathrm{Z'}}=2~\mathrm{TeV}$.

Expected exclusion limits at $95\%$ CL in the $|\theta_{23}|$--$|g_{\mathrm{Z'}}|$ plane for the $B_{3}\!-\!L_{2}$ model from JHEP 04 (2023) 033, for $m_{\mathrm{Z'}}=2~\mathrm{TeV}$.

Exclusion limits at $95\%$ CL in the $|\theta_{23}|$--$|g_{\mathrm{Z'}}|$ plane for the $B_{3}\!-\!L_{2}$ model from JHEP 04 (2023) 033, for $m_{\mathrm{Z'}}=2~\mathrm{TeV}$. The coupling values are shown at which the $\mathrm{Z'}$ width equals one half of the $\mu\mu$ invariant mass resolution. For larger values of the couplings, the narrow width approximation intrinsic to the search strategy is not considered valid.

Exclusion limits at $95\%$ CL in the $|g_{\mathrm{Z'}}|$--$m_{\mathrm{Z'}}$ plane for the $B_{3}\!-\!L_{2}$ model from JHEP 04 (2023) 033, for a fixed value of $\theta_{23}=0$. The solid black (dashed red) curve represents the observed (median expected) exclusion. The dotted curve denotes the coupling values at which the $\mathrm{Z'}$ width equals one half of the $\mu\mu$ invariant mass resolution. For larger values of the couplings, the narrow width approximation intrinsic to the search strategy is not considered valid. The region enclosed between the solid black (dashed red) and the dotted curves is (expected to be) excluded. The shaded blue area represents the $|g_{\mathrm{Z'}}|$ range preferred from a global fit in JHEP 04 (2023) 033 at $95\%$ CL.

Observed exclusion limits at $95\%$ CL in the $|g_{\mathrm{Z'}}|$--$m_{\mathrm{Z'}}$ plane for the $B_{3}\!-\!L_{2}$ model from JHEP 04 (2023) 033, for a fixed value of $\theta_{23}=0$.

Expected exclusion limits at $95\%$ CL in the $|g_{\mathrm{Z'}}|$--$m_{\mathrm{Z'}}$ plane for the $B_{3}\!-\!L_{2}$ model from JHEP 04 (2023) 033, for a fixed value of $\theta_{23}=0$.

Exclusion limits at $95\%$ CL in the $|g_{\mathrm{Z'}}|$--$m_{\mathrm{Z'}}$ plane for the $B_{3}\!-\!L_{2}$ model from JHEP 04 (2023) 033, for a fixed value of $\theta_{23}=0$. The coupling values are shown at which the $\mathrm{Z'}$ width equals one half of the $\mu\mu$ invariant mass resolution. For larger values of the couplings, the narrow width approximation intrinsic to the search strategy is not considered valid.

Reconstructed mass of the Z' candidate in CR1, which consists of flavor sidebands of SR1 (upper), SR2 (middle), and SR3 (lower) regions. Pre-fit (post-fit) results are shown on the left (right). The fitting procedure is described in Section 7.

Reconstructed mass of the Z' candidate in CR1, which consists of flavor sidebands of SR1 (upper), SR2 (middle), and SR3 (lower) regions. Pre-fit (post-fit) results are shown on the left (right). The fitting procedure is described in Section 7.

Reconstructed mass of the Z' candidate in CR1, which consists of flavor sidebands of SR1 (upper), SR2 (middle), and SR3 (lower) regions. Pre-fit (post-fit) results are shown on the left (right). The fitting procedure is described in Section 7.

Reconstructed mass of the Z' candidate in CR2, which consists of the dilepton mass sidebands of SR1 (upper), SR2 (middle), and SR3 (lower) regions. Post-fit dielectron (dimuon) channel results are shown on the left (right). The fitting procedure is described in Section 7.

Reconstructed mass of the Z' candidate in CR2, which consists of the dilepton mass sidebands of SR1 (upper), SR2 (middle), and SR3 (lower) regions. Post-fit dielectron (dimuon) channel results are shown on the left (right). The fitting procedure is described in Section 7.

Reconstructed mass of the Z' candidate in CR2, which consists of the dilepton mass sidebands of SR1 (upper), SR2 (middle), and SR3 (lower) regions. Post-fit dielectron (dimuon) channel results are shown on the left (right). The fitting procedure is described in Section 7.

Reconstructed mass of the Z' candidate in CR2, which consists of the dilepton mass sidebands of SR1 (upper), SR2 (middle), and SR3 (lower) regions. Post-fit dielectron (dimuon) channel results are shown on the left (right). The fitting procedure is described in Section 7.

Reconstructed mass of the Z' candidate in CR2, which consists of the dilepton mass sidebands of SR1 (upper), SR2 (middle), and SR3 (lower) regions. Post-fit dielectron (dimuon) channel results are shown on the left (right). The fitting procedure is described in Section 7.

Reconstructed mass of the Z' candidate in CR2, which consists of the dilepton mass sidebands of SR1 (upper), SR2 (middle), and SR3 (lower) regions. Post-fit dielectron (dimuon) channel results are shown on the left (right). The fitting procedure is described in Section 7.

Distributions of the reconstructed Z' candidate mass in SR1 (upper row), SR2 (middle row) and SR3 (lower row). Left (right) column corresponds to the dielectron (dimuon) channel. Signal samples with ($m_{Z'}$, $m_{N}$) = (4000 GeV, 200 GeV)$ and ($m_{Z'}$, $m_{N}$) = (4000 GeV, 1200 GeV)$ are plotted together with a cross section times branching fraction of 1 fb

Distributions of the reconstructed Z' candidate mass in SR1 (upper row), SR2 (middle row) and SR3 (lower row). Left (right) column corresponds to the dielectron (dimuon) channel. Signal samples with ($m_{Z'}$, $m_{N}$) = (4000 GeV, 200 GeV)$ and ($m_{Z'}$, $m_{N}$) = (4000 GeV, 1200 GeV)$ are plotted together with a cross section times branching fraction of 1 fb

Distributions of the reconstructed Z' candidate mass in SR1 (upper row), SR2 (middle row) and SR3 (lower row). Left (right) column corresponds to the dielectron (dimuon) channel. Signal samples with ($m_{Z'}$, $m_{N}$) = (4000 GeV, 200 GeV)$ and ($m_{Z'}$, $m_{N}$) = (4000 GeV, 1200 GeV)$ are plotted together with a cross section times branching fraction of 1 fb

Distributions of the reconstructed Z' candidate mass in SR1 (upper row), SR2 (middle row) and SR3 (lower row). Left (right) column corresponds to the dielectron (dimuon) channel. Signal samples with ($m_{Z'}$, $m_{N}$) = (4000 GeV, 200 GeV)$ and ($m_{Z'}$, $m_{N}$) = (4000 GeV, 1200 GeV)$ are plotted together with a cross section times branching fraction of 1 fb

Distributions of the reconstructed Z' candidate mass in SR1 (upper row), SR2 (middle row) and SR3 (lower row). Left (right) column corresponds to the dielectron (dimuon) channel. Signal samples with ($m_{Z'}$, $m_{N}$) = (4000 GeV, 200 GeV)$ and ($m_{Z'}$, $m_{N}$) = (4000 GeV, 1200 GeV)$ are plotted together with a cross section times branching fraction of 1 fb

Distributions of the reconstructed Z' candidate mass in SR1 (upper row), SR2 (middle row) and SR3 (lower row). Left (right) column corresponds to the dielectron (dimuon) channel. Signal samples with ($m_{Z'}$, $m_{N}$) = (4000 GeV, 200 GeV)$ and ($m_{Z'}$, $m_{N}$) = (4000 GeV, 1200 GeV)$ are plotted together with a cross section times branching fraction of 1 fb

The observed and expected 95\% CL upper limits on the product of \Zp boson cross section times branching fraction are shown for the case of ${m}_{N}$ = ${m}_{Z'}/4$ (upper row) and ${m}_{N}$ = 100 GeV (lower row) for dielectron (left column) and dimuon (right column) channels. The green and yellow bands indicate the 68\% and 95\% CL regions around the expected limit.

The observed and expected 95\% CL upper limits on the product of \Zp boson cross section times branching fraction are shown for the case of ${m}_{N}$ = ${m}_{Z'}/4$ (upper row) and ${m}_{N}$ = 100 GeV (lower row) for dielectron (left column) and dimuon (right column) channels. The green and yellow bands indicate the 68\% and 95\% CL regions around the expected limit.

The observed and expected 95\% CL upper limits on the product of \Zp boson cross section times branching fraction are shown for the case of ${m}_{N}$ = ${m}_{Z'}/4$ (upper row) and ${m}_{N}$ = 100 GeV (lower row) for dielectron (left column) and dimuon (right column) channels. The green and yellow bands indicate the 68\% and 95\% CL regions around the expected limit.

The observed and expected 95\% CL upper limits on the product of \Zp boson cross section times branching fraction are shown for the case of ${m}_{N}$ = ${m}_{Z'}/4$ (upper row) and ${m}_{N}$ = 100 GeV (lower row) for dielectron (left column) and dimuon (right column) channels. The green and yellow bands indicate the 68\% and 95\% CL regions around the expected limit.

Observed and expected exclusion regions at 95% CL in the 2D phase space of ${m}_{Z'}$ vs. ${m}_{N}$ for dielectron (left) and dimuon (right) channels. One standard deviation (s.d.) limits are also shown. Both opposite- and same-sign (OS and SS) dileptons from decays of heavy neutrino pairs are considered.

Observed and expected exclusion regions at 95% CL in the 2D phase space of ${m}_{Z'}$ vs. ${m}_{N}$ for dielectron (left) and dimuon (right) channels. One standard deviation (s.d.) limits are also shown. Both opposite- and same-sign (OS and SS) dileptons from decays of heavy neutrino pairs are considered.

Differential cross section of J/psi mesons from b hadrons as a function of dimuon pT in pp and PbPb collisions. The PbPb cross sections are normalised by TAA for direct comparison. Global uncertainties arise from the integrated luminosity uncertainty in pp collisions, and the number of minimum bias events and TAA uncertainties for PbPb collisions.

Differential cross section of prompt J/psi mesons as a function of dimuon rapidty in pp and PbPb collisions. The PbPb cross sections are normalised by TAA for direct comparison. Global uncertainties arise from the integrated luminosity uncertainty in pp collisions, and the number of minimum bias events and TAA uncertainties for PbPb collisions.

Differential cross section of J/psi mesons from b hadrons as a function of dimuon rapidty in pp and PbPb collisions. The PbPb cross sections are normalised by TAA for direct comparison. Global uncertainties arise from the integrated luminosity uncertainty in pp collisions, and the number of minimum bias events and TAA uncertainties for PbPb collisions.

Nuclear modification factor of prompt J/psi mesons as a function of dimuon rapidity. Global uncertainties arise from the integrated luminosity uncertainty of the pp data, and the number of minimum bias events and TAA uncertainties of the PbPb data.

Nuclear modification factor of prompt J/psi mesons as a function of collision centrality. Global uncertainties arise from the full pp statistical and systematic uncertainties (including integrated luminosity uncertainty), and the number of minimum bias events uncertainty of the PbPb data.

Nuclear modification factor of prompt J/psi mesons as a function of dimuon pT. Global uncertainties arise from the integrated luminosity uncertainty of the pp data, and the number of minimum bias events and TAA uncertainties of the PbPb data.

Nuclear modification factor of prompt J/psi mesons as a function of dimuon pT in the mid-rapidity interval. Global uncertainties arise from the integrated luminosity uncertainty of the pp data, and the number of minimum bias events and TAA uncertainties of the PbPb data.

Nuclear modification factor of prompt J/psi mesons as a function of dimuon pT in the most forward rapidity interval. Global uncertainties arise from the integrated luminosity uncertainty of the pp data, and the number of minimum bias events and TAA uncertainties of the PbPb data.

Nuclear modification factor of prompt J/psi mesons as a function of collision centrality in the mid- and most forward rapidity intervals. Global uncertainties arise from the full pp statistical and systematic uncertainties (including integrated luminosity uncertainty), and the number of minimum bias events uncertainty of the PbPb data.

Nuclear modification factor of prompt J/psi mesons as a function of pT in three centrality bins. Global uncertainties arise from the integrated luminosity uncertainty of the pp data, and the number of minimum bias events and TAA uncertainties of the PbPb data.

Nuclear modification factor of prompt J/psi mesons as a function of collision centrality in the most forward rapidity range at moderate and high pT. Global uncertainties arise from the full pp statistical and systematic uncertainties (including integrated luminosity uncertainty), and the number of minimum bias events uncertainty of the PbPb data.

Nuclear modification factor of prompt J/psi mesons as a function of collision centrality in the mid-rapidity range. Global uncertainties arise from the full pp statistical and systematic uncertainties (including integrated luminosity uncertainty), and the number of minimum bias events uncertainty of the PbPb data.

Nuclear modification factor of prompt psi(2S) mesons as a function of collision centrality in the mid-rapidity range. Global uncertainties arise from the full pp statistical and systematic uncertainties (including integrated luminosity uncertainty), and the number of minimum bias events uncertainty of the PbPb data.

95% CL intervals on the nuclear modification factor of prompt psi(2S) mesons as a function of collision centrality in the mid-rapidity range. Global uncertainties arise from the full pp statistical and systematic uncertainties (including integrated luminosity uncertainty), and the number of minimum bias events uncertainty of the PbPb data.

Nuclear modification factor of prompt J/psi and psi(2S) mesons as a function of dimuon pT in the mid-rapidity range. Global uncertainties arise from the integrated luminosity uncertainty of the pp data, and the number of minimum bias events and TAA uncertainties of the PbPb data.

Nuclear modification factor of prompt J/psi mesons as a function of collision centrality in the forward rapidity range. Global uncertainties arise from the full pp statistical and systematic uncertainties (including integrated luminosity uncertainty), and the number of minimum bias events uncertainty of the PbPb data.

Nuclear modification factor of prompt psi(2S) mesons as a function of collision centrality in the forward rapidity range. Global uncertainties arise from the full pp statistical and systematic uncertainties (including integrated luminosity uncertainty), and the number of minimum bias events uncertainty of the PbPb data.

95% CL intervals on the nuclear modification factor of prompt psi(2S) mesons as a function of collision centrality in the forward rapidity range. Global uncertainties arise from the full pp statistical and systematic uncertainties (including integrated luminosity uncertainty), and the number of minimum bias events uncertainty of the PbPb data.

Nuclear modification factor of prompt J/psi mesons as a function of dimuon pT in the forward rapidity range. Global uncertainties arise from the integrated luminosity uncertainty of the pp data, and the number of minimum bias events and TAA uncertainties of the PbPb data.

Nuclear modification factor of prompt psi(2S) mesons as a function of dimuon pT in the forward rapidity range. Global uncertainties arise from the integrated luminosity uncertainty of the pp data, and the number of minimum bias events and TAA uncertainties of the PbPb data.

95% CL intervals on the nuclear modification factor of prompt psi(2S) mesons as a function of dimuon pT in the forward rapidity range. Global uncertainties arise from the integrated luminosity uncertainty of the pp data, and the number of minimum bias events and TAA uncertainties of the PbPb data.

Nuclear modification factor of nonprompt J/psi mesons as a function of dimuon rapidity. Global uncertainties arise from the integrated luminosity uncertainty of the pp data, and the number of minimum bias events and TAA uncertainties of the PbPb data.

Nuclear modification factor of nonprompt J/psi mesons as a function of collision centrality. Global uncertainties arise from the full pp statistical and systematic uncertainties (including integrated luminosity uncertainty), and the number of minimum bias events uncertainty of the PbPb data.

Nuclear modification factor of nonprompt J/psi mesons as a function of dimuon pT. Global uncertainties arise from the integrated luminosity uncertainty of the pp data, and the number of minimum bias events and TAA uncertainties of the PbPb data.

Nuclear modification factor of nonprompt J/psi mesons as a function of dimuon pT in the mid-rapidity interval. Global uncertainties arise from the integrated luminosity uncertainty of the pp data, and the number of minimum bias events and TAA uncertainties of the PbPb data.

Nuclear modification factor of nonprompt J/psi mesons as a function of dimuon pT in the most forward rapidity interval. Global uncertainties arise from the integrated luminosity uncertainty of the pp data, and the number of minimum bias events and TAA uncertainties of the PbPb data.

Nuclear modification factor of nonprompt J/psi mesons as a function of collision centrality in the mid- and most forward rapidity intervals. Global uncertainties arise from the full pp statistical and systematic uncertainties (including integrated luminosity uncertainty), and the number of minimum bias events uncertainty of the PbPb data.

Nuclear modification factor of nonprompt J/psi mesons as a function of pT in three centrality bins. Global uncertainties arise from the integrated luminosity uncertainty of the pp data, and the number of minimum bias events and TAA uncertainties of the PbPb data.

Nuclear modification factor of nonprompt J/psi mesons as a function of collision centrality in the most forward rapidity range at moderate and high pT. Global uncertainties arise from the full pp statistical and systematic uncertainties (including integrated luminosity uncertainty), and the number of minimum bias events uncertainty of the PbPb data.