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1. Measurement of CP violation in B0 → D+D− and $$ {\textrm{B}}_{\textrm{s}}^0 $$ → $$ {\textrm{D}}_{\textrm{s}}^{+}{\textrm{D}}_{\textrm{s}}^{-} $$ decays

   https://doi.org/10.1007/JHEP01(2025)061  

   Aaij, R; Abdelmotteleb, A_S W; Abellan_Beteta, C; Abudinén, F; Ackernley, T; Adefisoye, A A; Adeva, B; Adinolfi, M; Adlarson, P; Agapopoulou, C; et al (January 2025, Journal of High Energy Physics)

   A<sc>bstract</sc> A time-dependent, flavour-tagged measurement ofCPviolation is performed withB⁰→ D⁺D⁻and$$ {B}_s^0 $$ $B_s^0$ →$$ {D}_s^{+}{D}_s^{-} $$ $D_s^{+}{D}_s^{-}$ decays, using data collected by the LHCb detector in proton-proton collisions at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of 6 fb⁻¹. InB⁰→ D⁺D⁻decays theCP-violation parameters are measured to be$$ {\displaystyle \begin{array}{c}{S}_{D^{+}{D}^{-}}=-0.552\pm 0.100\left(\textrm{stat}\right)\pm 0.010\left(\textrm{syst}\right),\\ {}{C}_{D^{+}{D}^{-}}=0.128\pm 0.103\left(\textrm{stat}\right)\pm 0.010\left(\textrm{syst}\right).\end{array}} $$ $\begin{array}{c}{S}_{D^{+}{D}^{-}}=-0.552\pm 0.100\left(\text{stat}\right)\pm 0.010\left(\text{syst}\right),\\ C_{D^{+}{D}^{-}}=0.128\pm 0.103\left(\text{stat}\right)\pm 0.010\left(\text{syst}\right).\end{array}$ In$$ {B}_s^0 $$ $B_s^0$ →$$ {D}_s^{+}{D}_s^{-} $$ $D_s^{+}{D}_s^{-}$ decays theCP-violating parameter formulation in terms ofϕ_sand|λ|results in$$ {\displaystyle \begin{array}{c}{\phi}_s=-0.086\pm 0.106\left(\textrm{stat}\right)\pm 0.028\left(\textrm{syst}\right)\textrm{rad},\\ {}\mid {\lambda}_{D_s^{+}{D}_s^{-}}\mid =1.145\pm 0.126\left(\textrm{stat}\right)\pm 0.031\left(\textrm{syst}\right).\end{array}} $$ $\begin{array}{c}{\varphi }_s=-0.086\pm 0.106\left(\text{stat}\right)\pm 0.028\left(\text{syst}\right)\mathrm{rad},\\ \mid {\lambda }_{D_s^{+}{D}_s^{-}}\mid =1.145\pm 0.126\left(\text{stat}\right)\pm 0.031\left(\text{syst}\right).\end{array}$ These results represent the most precise single measurement of theCP-violation parameters in their respective channels. For the first time in a single measurement,CPsymmetry is observed to be violated inB⁰→ D⁺D⁻decays with a significance exceeding six standard deviations. 

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2. Measurement of the $$ {\varOmega}_c^0 $$ and $$ {\Xi}_c^0 $$ baryon lifetimes using hadronic b-baryon decays

   https://doi.org/10.1007/JHEP09(2025)157  

   Aaij, R; Abdelmotteleb, A_S W; Abellan_Beteta, C; Abudinén, F; Ackernley, T; Adefisoye, A A; Adeva, B; Adinolfi, M; Adlarson, P; Agapopoulou, C; et al (September 2025, Journal of High Energy Physics)

   A<sc>bstract</sc> The lifetimes of the$$ {\varOmega}_c^0 $$ ${\Omega }_c^0$ and$$ {\Xi}_c^0 $$ ${\Xi }_c^0$ baryons are measured using appcollision dataset collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb⁻¹. The charm baryons are produced in the fully reconstructed decay chains$$ {\varOmega}_b^{-}\to {\varOmega}_c^0\left(\to p{K}^{-}{K}^{-}{\pi}^{+}\right){\pi}^{-} $$ ${\Omega }_b^{-}\to {\Omega }_c^0\left(\to p{K}^{-}{K}^{-}{\pi }^{+}\right){\pi }^{-}$ and$$ {\Xi}_b^{-}\to {\Xi}_c^0\left(\to p{K}^{-}{K}^{-}{\pi}^{+}\right){\pi}^{-} $$ ${\Xi }_b^{-}\to {\Xi }_c^0\left(\to p{K}^{-}{K}^{-}{\pi }^{+}\right){\pi }^{-}$ . The measurement uses topologically and kinematically similarB⁻→D⁰(→K⁻K⁺π⁻π⁺)π⁻decays for normalisation. The measured lifetimes are$$ {\displaystyle \begin{array}{c}{\tau}_{\varOmega_c^0}=276.3\pm 19.4\left(\textrm{stat}\right)\pm 1.8\left(\textrm{syst}\right)\pm 0.7\left({\tau}_{D^0}\right)\textrm{fs},\\ {}{\tau}_{\Xi_c^0}=149.2\pm 2.5\left(\textrm{stat}\right)\pm 0.9\left(\textrm{syst}\right)\pm 0.4\ \left({\tau}_{D^0}\right)\textrm{fs},\end{array}} $$ $\begin{array}{c}{\tau }_{{\Omega }_c^0}=276.3\pm 19.4\left(\text{stat}\right)\pm 1.8\left(\text{syst}\right)\pm 0.7\left({\tau }_{D^0}\right)\mathrm{fs},\\ {\tau }_{{\Xi }_c^0}=149.2\pm 2.5\left(\text{stat}\right)\pm 0.9\left(\text{syst}\right)\pm 0.4\left({\tau }_{D^0}\right)\mathrm{fs},\end{array}$ where the first uncertainty is statistical, the second systematic and the third due to the uncertainty of theD⁰lifetime. These results are consistent with previous measurements performed by the LHCb experiment. 

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3. Search for the $$ {B}_s^0 $$ → μ+μ−γ decay

   https://doi.org/10.1007/JHEP07(2024)101  

   Aaij, R; Abdelmotteleb, A_S W; Abellan_Beteta, C; Abudinén, F; Ackernley, T; Adefisoye, A A; Adeva, B; Adinolfi, M; Adlarson, P; Agapopoulou, C; et al (July 2024, Journal of High Energy Physics)

   A<sc>bstract</sc> A search for the fully reconstructed$$ {B}_s^0 $$ $B_s^0$ → μ⁺μ⁻γdecay is performed at the LHCb experiment using proton-proton collisions at$$ \sqrt{s} $$ $\sqrt{s}$ = 13 TeV corresponding to an integrated luminosity of 5.4 fb⁻¹. No significant signal is found and upper limits on the branching fraction in intervals of the dimuon mass are set$$ {\displaystyle \begin{array}{cc}\mathcal{B}\left({B}_s^0\to {\mu}^{+}{\mu}^{-}\gamma \right)<4.2\times {10}^{-8},& m\left({\mu}^{+}{\mu}^{-}\right)\in \left[2{m}_{\mu },1.70\right]\textrm{GeV}/{c}^2,\\ {}\mathcal{B}\left({B}_s^0\to {\mu}^{+}{\mu}^{-}\gamma \right)<7.7\times {10}^{-8},&\ m\left({\mu}^{+}{\mu}^{-}\right)\in \left[\textrm{1.70,2.88}\right]\textrm{GeV}/{c}^2,\\ {}\mathcal{B}\left({B}_s^0\to {\mu}^{+}{\mu}^{-}\gamma \right)<4.2\times {10}^{-8},& m\left({\mu}^{+}{\mu}^{-}\right)\in \left[3.92,{m}_{B_s^0}\right]\textrm{GeV}/{c}^2,\end{array}} $$ $\begin{array}{cc}B\left(B_s^0\to {\mu }^{+}{\mu }^{-}\gamma \right)<4.2\times {10}^{-8},& m\left({\mu }^{+}{\mu }^{-}\right)\in \left(2m_{\mu },1.70\right)\mathrm{GeV}/c^2,\\ B\left(B_s^0\to {\mu }^{+}{\mu }^{-}\gamma \right)<7.7\times {10}^{-8},& m\left({\mu }^{+}{\mu }^{-}\right)\in \left(\mathrm{1.70,\; 2.88}\right)\mathrm{GeV}/c^2,\\ B\left(B_s^0\to {\mu }^{+}{\mu }^{-}\gamma \right)<4.2\times {10}^{-8},& m\left({\mu }^{+}{\mu }^{-}\right)\in \left(3.92,m_{B_s^0}\right)\mathrm{GeV}/c^2,\end{array}$ at 95% confidence level. Additionally, upper limits are set on the branching fraction in the [2m_μ,1.70] GeV/c²dimuon mass region excluding the contribution from the intermediateϕ(1020) meson, and in the region combining all dimuon-mass intervals. 

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4. Measurement of the W → μν cross-sections as a function of the muon transverse momentum in pp collisions at 5.02 TeV

   https://doi.org/10.1007/JHEP03(2026)148  

   Aaij, R; Abdelmotteleb, A_S W; Abellan_Beteta, C; Abudinén, F; Ackernley, T; Adefisoye, A A; Adeva, B; Adinolfi, M; Adlarson, P; Agapopoulou, C; et al (March 2026, Journal of High Energy Physics)

   A<sc>bstract</sc> Thepp→W^±(→μ^±ν_μ)Xcross-sections are measured at a proton-proton centre-of-mass energy$$ \sqrt{s}=5.02 $$ $\sqrt{s}=5.02$ TeV using a dataset corresponding to an integrated luminosity of 100 pb⁻¹recorded by the LHCb experiment. Considering muons in the pseudorapidity range 2.2< η <4.4, the cross-sections are measured differentially in twelve intervals of muon transverse momentum between 28< p_T<52 GeV. Integrated overp_T, the measured cross-sections are$$ {\displaystyle \begin{array}{c}{\sigma}_{W^{+}\to {\mu}^{+}{\nu}_{\mu }}=300.9\pm 2.4\pm 3.8\pm 6.0\ \textrm{pb},\\ {}{\sigma}_{W^{-}\to {\mu}^{-}{\overline{\nu}}_{\mu }}=236.9\pm 2.1\pm 2.7\pm 4.7\ \textrm{pb},\end{array}} $$ $\begin{array}{c}{\sigma }_{W^{+}\to {\mu }^{+}{\nu }_{\mu }}=300.9\pm 2.4\pm 3.8\pm 6.0\mathrm{pb},\\ {\sigma }_{W^{-}\to {\mu }^{-}{\overline{\nu }}_{\mu }}=236.9\pm 2.1\pm 2.7\pm 4.7\mathrm{pb},\end{array}$ where the first uncertainties are statistical, the second are systematic, and the third are associated with the luminosity calibration. These integrated results are consistent with theoretical predictions. This analysis introduces a new method to determine theW-boson mass using the measured differential cross-sections corrected for detector effects. The measurement is performed on this statistically limited dataset as a proof of principle and yields$$ {m}_W=80369\pm 130\pm 33\ \textrm{MeV}, $$ $m_W=80369\pm 130\pm 33\mathrm{MeV},$ where the first uncertainty is experimental and the second is theoretical. 

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5. Improved measurement of η/η′ mixing in $$ {B}_{(s)}^0\to J/\psi {\eta}^{\left(\prime \right)} $$ decays

   https://doi.org/10.1007/JHEP10(2025)113  

   Aaij, R; Abdelmotteleb, A_S W; Abellan_Beteta, C; Abudinén, F; Ackernley, T; Adefisoye, A A; Adeva, B; Adinolfi, M; Adlarson, P; Agapopoulou, C; et al (October 2025, Journal of High Energy Physics)

   A<sc>bstract</sc> Branching fraction ratios between the decays$$ {B}_{(s)}^0\to J/\psi {\eta}^{\left(\prime \right)} $$ $B_{\left(s\right)}^0\to J/\psi {\eta }^{\left(\prime \right)}$ are measured using proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of 9 fb⁻¹. The measured ratios of these branching fractions are$$ {\displaystyle \begin{array}{c}\frac{\mathcal{B}\left({B}^0\to J/{\psi \eta}^{\prime}\right)}{\mathcal{B}\left({B}^0\to J/\psi \eta \right)}=0.48\pm 0.06\pm 0.02\pm 0.01,\\ {}\frac{\mathcal{B}\left({B}_s^0\to J/{\psi \eta}^{\prime}\right)}{\mathcal{B}\left({B}_s^0\to J/\psi \eta \right)}=0.80\pm 0.02\pm 0.02\pm 0.01,\end{array}} $$ $\begin{array}{c}\frac{B\left(B^0\to J/{\mathrm{\psi \eta }}^{\prime }\right)}{B\left(B^0\to J/\mathrm{\psi \eta }\right)}=0.48\pm 0.06\pm 0.02\pm 0.01,\\ \frac{B\left(B_s^0\to J/{\mathrm{\psi \eta }}^{\prime }\right)}{B\left(B_s^0\to J/\mathrm{\psi \eta }\right)}=0.80\pm 0.02\pm 0.02\pm 0.01,\end{array}$ where the uncertainties are statistical, systematic and related to the precision of theη^(′)branching fractions, respectively. They are used to constrain theη/η′ mixing angle,ϕ_P, and to probe the presence of a possible glueball component in theη′ meson, described by the gluonic mixing angleϕ_G. The obtained results are $$ {\displaystyle \begin{array}{c}{\phi}_{\textrm{P}}={\left({41.6}_{-1.2}^{+1.0}\right)}^{\circ },\\ {}{\phi}_{\textrm{G}}={\left({28.1}_{-4.0}^{+3.9}\right)}^{\circ },\end{array}} $$ $\begin{array}{c}{\varphi }_P={\left({41.6}_{-1.2}^{+1.0}\right)}^{\circ },\\ {\varphi }_G={\left({28.1}_{-4.0}^{+3.9}\right)}^{\circ },\end{array}$ where the uncertainties are statistically dominated. While the value ofϕ_Pis compatible with existing experimental determinations and theoretical calculations, the angleϕ_Gdiffers from zero by more than four standard deviations, which points to a substantial glueball component in theη′ meson and/or unexpectedly large contributions from gluon-mediated processes in these decays. The absolute branching fractions are also measured relative to that of the well-established$$ {B}_s^0\to J/\psi \phi $$ $B_s^0\to J/\mathrm{\psi \varphi }$ decay, which serves as the normalisation channel. These results supersede the previous LHCb measurements and are the most precise to date. 

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