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Abstract:

A search for the decay B0→ ϕϕ is made using pp collision data collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of 9 fb−1. No significant signal is observed, and an upper limit on the branching fraction of 1.3 (1.4) × 10−8 at 90 (95)% confidence level is set. This result supersedes the previous LHCb study and improves the upper limit by a factor of two.

Abstract:

A bstract A search for the decay B 0 → ϕϕ is made using pp collision data collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of 9 fb − 1 . No significant signal is observed, and an upper limit on the branching fraction of 1 . 3 (1 . 4) × 10 − 8 at 90 (95)% confidence level is set. This result supersedes the previous LHCb study and improves the upper limit by a factor of two.

Abstract:

The transverse polarization of $\mathrm{Âì}$ and $\stackrel{¯}{\mathrm{Âì}}$ hyperons is measured in $p\mathrm{Pb}$ collisions collected by the LHCb experiment at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The polarization is averaged over hyperon transverse momentum in the range $0.15<p_{\mathrm{T}}<6.00\mathrm{GeV}/c$ , and Feynman- $x$ in the ranges $0.005<x_{\mathrm{F}}<0.040$ (forward region) and $−0.10<x_{\mathrm{F}}<−0.01$ (backward region) defined relative to the proton beam direction. The transverse polarization is found to be compatible with zero for both $\mathrm{Âì}$ and $\stackrel{¯}{\mathrm{Âì}}$ hyperons. The results are also measured as a function of $p_{\mathrm{T}}$ and $x_{\mathrm{F}}$ with no significant dependence on these variables observed. The results are compared with previous experimental measurements at different center-of-mass energies and collision environments.

Abstract:

The study of a wide peaking structure in the $B_c^{+}\mathrm{γ}$ mass spectrum is reported using a data sample of proton-proton collisions collected by the LHCb detector at center-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of $9{\mathrm{fb}}^{−1}$ . The observed structure is consistent with the lowest excited $P$ -wave $B_c^{+}$ states and exhibits a statistical significance exceeding 7 standard deviations relative to the background-only hypothesis. A two-peak model serves as an effective description of the data, with various theory-constrained models further explored to provide physical interpretation. Based on the predictions for the $B_c(1P{)}^{+}$ spectrum, the relative production cross section of the overall $B_c(1P{)}^{+}$ states with respect to the $B_c^{+}$ ground state with the transverse momentum $p_{\mathrm{T}}$ and rapidity $y$ of $B_c^{+}$ mesons in the regions $p_{\mathrm{T}}<20\mathrm{GeV}/c$ and $2.0<y<4.5$ at $\sqrt{s}=13\mathrm{TeV}$ is measured to be $0.20Â\pm 0.03Â\pm 0.02Â\pm 0.03$ , where the uncertainty terms represent statistical, systematic, and uncertainties related to the choice of theoretical models, respectively. The results provide a test of theoretical models and deepen our understanding of quantum chromodynamics.

Abstract:

A study of the difference in the CP asymmetries between Âì b 0 → J / ψ p Ï€ - and Âì b 0 → J / ψ pK - decays, Δ A CP , is performed using proton-proton collision data collected by the LHCb experiment in the years 2015–2018, corresponding to an integrated luminosity of 6 fb - 1 . This quantity is measured to be Δ A CP = ( 4.03 ± 1.18 ± 0.23 ) % , where the first uncertainty is statistical and the second is systematic. When combined with the previous LHCb result, a value of Δ A CP = ( 4.31 ± 1.06 ± 0.28 ) % is obtained, corresponding to a significance of 3.9 σ against the CP symmetry hypothesis. Studies of triple-product asymmetries, which provide an additional probe of CP violation, show no significant deviation from CP symmetry.