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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. 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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3. Probing light scalars and vector-like quarks at the high-luminosity LHC

   https://doi.org/10.1140/epjc/s10052-025-14085-1  

   Qureshi, U S; Gurrola, A; Flórez, A; Rodriguez, C (April 2025, The European Physical Journal C)

   Abstract A model based on a$$U(1)_{T^3_R}$$ $U{\left(1\right)}_{T_R^3}$ extension of the Standard Model can address the mass hierarchy between generations of fermions, explain thermal dark matter abundance, and the muon$$g - 2$$ $g-2$ ,$$R_{(D)}$$ $R_{\left(D\right)}$ , and$$R_{(D^*)}$$ $R_{\left(D^{\ast }\right)}$ anomalies. The model contains a light scalar boson$$\phi '$$ ${\varphi }^{\prime }$ and a heavy vector-like quark$$\chi _\textrm{u}$$ ${\chi }_{\text{u}}$ that can be probed at CERN’s large hadron collider (LHC). We perform a phenomenology study on the production of$$\phi '$$ ${\varphi }^{\prime }$ and$${\chi }_u$$ ${\chi }_u$ particles from proton–proton$$(\textrm{pp})$$ $\left(\text{pp}\right)$ collisions at the LHC at$$\sqrt{s}=13.6$$ $\sqrt{s}=13.6$ TeV, primarily through$$g{-g}$$ $g-g$ and$$t{-\chi _\textrm{u}}$$ $t-{\chi }_{\text{u}}$ fusion. We work under a simplified model approach and directly take the$$\chi _\textrm{u}$$ ${\chi }_{\text{u}}$ and$$\phi '$$ ${\varphi }^{\prime }$ masses as free parameters. We perform a phenomenological analysis considering$$\chi _\textrm{u}$$ ${\chi }_{\text{u}}$ final states to b-quarks, muons, and neutrinos, and$$\phi '$$ ${\varphi }^{\prime }$ decays to$$\mu ^+\mu ^-$$ ${\mu }^{+}{\mu }^{-}$ . A machine learning algorithm is used to maximize the signal sensitivity, considering an integrated luminosity of 3000$$\text {fb}^{-1}$$ ${\text{fb}}^{-1}$ . The proposed methodology can be a key mode for discovery over a large mass range, including low masses, traditionally considered difficult due to experimental constraints. 

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4. Light-flavor particle production in high-multiplicity pp collisions at $$ \sqrt{\textrm{s}} $$ = 13 TeV as a function of transverse spherocity

   https://doi.org/10.1007/JHEP05(2024)184  

   Acharya, S; Adamová, D; Aglieri_Rinella, G; Agnello, M; Agrawal, N; Ahammed, Z; Ahmad, S; Ahn, S U; Ahuja, I; Akindinov, A; et al (May 2024, Journal of High Energy Physics)

   A<sc>bstract</sc> Results on the transverse spherocity dependence of light-flavor particle production (π, K, p,ϕ, K^*0,$$ {\textrm{K}}_{\textrm{S}}^0 $$ $K_S^0$ , Λ, Ξ) at midrapidity in high-multiplicity pp collisions at$$ \sqrt{s} $$ $\sqrt{s}$ = 13 TeV were obtained with the ALICE apparatus. The transverse spherocity estimator$$ \left({S}_{\textrm{O}}^{p_{\textrm{T}}=1}\right) $$ $\left(S_O^{p_T=1}\right)$ categorizes events by their azimuthal topology. Utilizing narrow selections on$$ {S}_{\textrm{O}}^{p_{\textrm{T}}=1} $$ $S_O^{p_T=1}$ , it is possible to contrast particle production in collisions dominated by many soft initial interactions with that observed in collisions dominated by one or more hard scatterings. Results are reported for two multiplicity estimators covering different pseudorapidity regions. The$$ {S}_{\textrm{O}}^{p_{\textrm{T}}=1} $$ $S_O^{p_T=1}$ estimator is found to effectively constrain the hardness of the events when the midrapidity (|η| < 0.8) estimator is used. The production rates of strange particles are found to be slightly higher for soft isotropic topologies, and severely suppressed in hard jet-like topologies. These effects are more pronounced for hadrons with larger mass and strangeness content, and observed when the topological selection is done within a narrow multiplicity interval. This demonstrates that an important aspect of the universal scaling of strangeness enhancement with final-state multiplicity is that high-multiplicity collisions are dominated by soft, isotropic processes. On the contrary, strangeness production in events with jet-like processes is significantly reduced. The results presented in this article are compared with several QCD-inspired Monte Carlo event generators. Models that incorporate a two-component phenomenology, either through mechanisms accounting for string density, or thermal production, are able to describe the observed strangeness enhancement as a function of$$ {S}_{\textrm{O}}^{p_{\textrm{T}}=1} $$ $S_O^{p_T=1}$ . 

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5. Measurement of the branching fractions of $$ \overline{B} $$ → D(*)K−$$ {K}_{(S)}^{\left(\ast \right)0} $$ and $$ \overline{B} $$ → D(*)$$ {D}_s^{-} $$ decays at Belle II

   https://doi.org/10.1007/JHEP08(2024)206  

   Adachi, I; Aggarwal, L; Aihara, H; Akopov, N; Aloisio, A; Althubiti, N; Anh_Ky, N; Asner, D M; Atmacan, H; Aushev, T; et al (August 2024, Journal of High Energy Physics)

   Abstract We present measurements of the branching fractions of eight$$ {\overline{B}}^0 $$ ${\overline{B}}^0$ →D^(*)+K⁻$$ {K}_{(S)}^{\left(\ast \right)0} $$ $K_{\left(S\right)}^{\left(\ast \right)0}$ ,B⁻→D^(*)0K⁻$$ {K}_{(S)}^{\left(\ast \right)0} $$ $K_{\left(S\right)}^{\left(\ast \right)0}$ decay channels. The results are based on data from SuperKEKB electron-positron collisions at the Υ(4S) resonance collected with the Belle II detector, corresponding to an integrated luminosity of 362 fb⁻¹. The event yields are extracted from fits to the distributions of the difference between expected and observedBmeson energy, and are efficiency-corrected as a function ofm(K⁻$$ {K}_{(S)}^{\left(\ast \right)0} $$ $K_{\left(S\right)}^{\left(\ast \right)0}$ ) andm(D^(*)$$ {K}_{(S)}^{\left(\ast \right)0} $$ $K_{\left(S\right)}^{\left(\ast \right)0}$ ) in order to avoid dependence on the decay model. These results include the first observation of$$ {\overline{B}}^0 $$ ${\overline{B}}^0$ →D⁺K⁻$$ {K}_S^0 $$ $K_S^0$ ,B⁻→D*⁰K⁻$$ {K}_S^0 $$ $K_S^0$ , and$$ {\overline{B}}^0 $$ ${\overline{B}}^0$ →D*⁺K⁻$$ {K}_S^0 $$ $K_S^0$ decays and a significant improvement in the precision of the other channels compared to previous measurements. The helicity-angle distributions and the invariant mass distributions of theK⁻$$ {K}_{(S)}^{\left(\ast \right)0} $$ $K_{\left(S\right)}^{\left(\ast \right)0}$ systems are compatible with quasi-two-body decays via a resonant transition with spin-parityJ^P= 1⁻for theK⁻$$ {K}_S^0 $$ $K_S^0$ systems andJ^P= 1⁺for theK⁻K*⁰systems. We also present measurements of the branching fractions of four$$ {\overline{B}}^0 $$ ${\overline{B}}^0$ →D^(*)+$$ {D}_s^{-} $$ $D_s^{-}$ ,B⁻→D^(*)0$$ {D}_s^{-} $$ $D_s^{-}$ decay channels with a precision compatible to the current world averages. 

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