Measurement of CP observables in B± → D(*)K± and B± → D(*)π± decays using two-body D final states
A bstract Measurements of CP observables in B ± → D (*) K ± and B ± → D (*) π ± decays are presented, where D (∗) indicates a neutral D or D ∗ meson that is an admixture of meson and anti-meson states. Decays of the D (∗) meson to the Dπ 0 and Dγ final states are partially reconstructed without inclusion of the neutral pion or photon. Decays of the D meson are reconstructed in the K ± π ∓ , K + K − , and π + π − final states. The analysis uses a sample of charged B mesons produced in proton-proton collisions and collected with the LHCb experiment, corresponding to integrated luminosities of 2.0, 1.0, and 5.7 fb − 1 taken at centre-of-mass energies of 7, 8, and 13 TeV, respectively. The measurements of partially reconstructed B ± → D (*) K ± and B ± → D (∗) π ± with D → K ∓ π ± decays are the first of their kind, and a first observation of the B ± → $${\left(D{\pi}^0\right)}_{D^{\ast }}{\pi}^{\pm }$$ D π 0 D ∗ π ± decay is made with a significance of more »
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Award ID(s):
Publication Date:
NSF-PAR ID:
10349078
Journal Name:
Journal of High Energy Physics
Volume:
2021
Issue:
4
ISSN:
1029-8479
1. A bstract Searches for CP violation in the two-body decays $${D}_{(s)}^{+}\to {h}^{+}{\pi}^0$$ D s + → h + π 0 and $${D}_{(s)}^{+}\to {h}^{+}\eta$$ D s + → h + η (where h + denotes a π + or K + meson) are performed using pp collision data collected by the LHCb experiment corresponding to either 9 fb − 1 or 6 fb − 1 of integrated luminosity. The π 0 and η mesons are reconstructed using the e + e − γ final state, which can proceed as three-body decays π 0 → e + e − γ and η → e + e − γ , or via the two-body decays π 0 → γγ and η → γγ followed by a photon conversion. The measurements are made relative to the control modes $${D}_{(s)}^{+}\to {K}_{\mathrm{S}}^0{h}^{+}$$ D s + → K S 0 h + to cancel the production and detection asymmetries. The CP asymmetries are measured to be $${\displaystyle \begin{array}{c}{\mathcal{A}}_{CP}\left({D}^{+}\to {\pi}^{+}{\pi}^0\right)=\left(-1.3\pm 0.9\pm 0.6\right)\%,\\ {}{\mathcal{A}}_{CP}\left({D}^{+}\to {K}^{+}{\pi}^0\right)=\left(-3.2\pm 4.7\pm 2.1\right)\%,\\ {}\begin{array}{c}{\mathcal{A}}_{CP}\left({D}^{+}\to {\pi}^{+}\eta \right)=\left(-0.2\pm 0.8\pm 0.4\right)\%,\\ {}{\mathcal{A}}_{CP}\left({D}^{+}\to {K}^{+}\eta \right)=\left(-6\pm 10\pm 4\right)\%,\\ {}\begin{array}{c}{\mathcal{A}}_{CP}\left({D}_s^{+}\to {K}^{+}{\pi}^0\right)=\left(-0.8\pm 3.9\pm 1.2\right)\%,\\ {}\begin{array}{c}{\mathcal{A}}_{CP}\left({D}_s^{+}\to {\pi}^{+}\eta \right)=\left(0.8\pm 0.7\pm 0.5\right)\%,\\ {}{\mathcal{A}}_{CP}\left({D}_s^{+}\to {K}^{+}\eta \right)=\left(0.9\pm 3.7\pm 1.1\right)\%,\end{array}\end{array}\end{array}\end{array}}$$more »
2. A bstract A data set corresponding to an integrated luminosity of 9 fb − 1 of proton-proton collisions collected by the LHCb experiment has been analysed to search for $${B}_c^{+}\to {D}_{(s)}^{\left(\ast \right)+}{\genfrac{}{}{0pt}{}{\left(\hbox{---} \right)}{D}}^{\left(\ast \right)0}$$ B c + → D s ∗ + — D ∗ 0 decays. The decays are fully or partially reconstructed, where one or two missing neutral pions or photons from the decay of an excited charm meson are allowed. Upper limits for the branching fractions, normalised to B + decays to final states with similar topologies, are obtained for sixteen $${B}_c^{+}$$ B c + decay modes. For the decay $${B}_c^{+}\to {D}_s^{+}{\overline{D}}^0$$ B c + → D s + D ¯ 0 , an excess with a significance of 3.4 standard deviations is found.
3. A bstract The first full angular analysis of the $${B}^0\to {D}^{\ast -}{D}_s^{\ast +}$$ B 0 → D ∗ − D s ∗ + decay is performed using 6 fb − 1 of pp collision data collected with the LHCb experiment at a centre-of-mass energy of 13 TeV. The $${D}_s^{\ast +}\to {D}_s^{+}\gamma$$ D s ∗ + → D s + γ and D * − → $${\overline{D}}^0{\pi}^{-}$$ D ¯ 0 π − vector meson decays are used with the subsequent $${D}_s^{+}$$ D s + → K + K − π + and $${\overline{D}}^0$$ D ¯ 0 → K + π − decays. All helicity amplitudes and phases are measured, and the longitudinal polarisation fraction is determined to be f L = 0 . 578 ± 0 . 010 ± 0 . 011 with world-best precision, where the first uncertainty is statistical and the second is systematic. The pattern of helicity amplitude magnitudes is found to align with expectations from quark-helicity conservation in B decays. The ratio of branching fractions [ℬ( $${B}^0\to {D}^{\ast -}{D}_s^{\ast +}$$ B 0 → D ∗ − D s ∗ + ) × ℬ( $${D}_s^{\astmore » 4. Abstract The multihadron decays$$ {\Lambda}_b^0 $$Λ b 0 → D + pπ−π− and$$ {\Lambda}_b^0 $$Λ b 0 → D * + pπ−π− are observed in data corresponding to an integrated luminosity of 3 fb − 1 , collected in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV by the LHCb detector. Using the decay$$ {\Lambda}_b^0 $$Λ b 0 →$$ {\Lambda}_c^{+} $$Λ c + π + π − π − as a normalisation channel, the ratio of branching fractions is measured to be$$ \frac{\mathcal{B}\left({\Lambda}_b^0\to {D}^{+}p{\pi}^{-}{\pi}^{-}\right)}{\mathcal{B}\left({\Lambda}_b^0\to {\Lambda}_c^0{\pi}^{+}{\pi}^{-}{\pi}^{-}\right)}\times \frac{\mathcal{B}\left({D}^{+}\to {K}^{-}{\pi}^{+}{\pi}^{+}\right)}{\mathcal{B}\left({\Lambda}_c^0\to {pK}^{-}{\pi}^{-}\right)}=\left(5.35\pm 0.21\pm 0.16\right)\%, $$B Λ b 0 → D + p π − π − B Λ b 0 → Λ c 0 π + π − π − × B D + → K − π + π + B Λ c 0 → pK − π − = 5.35 ± 0.21 ± 0.16 % , where the first uncertainty is statistical and the second systematic. The ratio of branching fractions for the$$ {\Lambda}_b^0 $$Λ b 0 → D *+ pπ − π − and$$ {\Lambda}_b^0 $$Λ b 0 → D + pπ − π −more » 5. A bstract The p T -differential production cross sections of prompt and non-prompt (produced in beauty-hadron decays) D mesons were measured by the ALICE experiment at midrapidity ( | y | < 0 . 5) in proton-proton collisions at$$ \sqrt{s} $$s = 5 . 02 TeV. The data sample used in the analysis corresponds to an integrated luminosity of (19 . 3 ± 0 . 4) nb − 1 . D mesons were reconstructed from their decays D 0 → K − π + , D + → K − π + π + , and$$ {\mathrm{D}}_{\mathrm{s}}^{+}\to \upphi {\uppi}^{+}\to {\mathrm{K}}^{-}{\mathrm{K}}^{+}{\uppi}^{+} $$D s + → ϕ π + → K − K + π + and their charge conjugates. Compared to previous measurements in the same rapidity region, the cross sections of prompt D + and$$ {\mathrm{D}}_{\mathrm{s}}^{+}  D s + mesons have an extended p T coverage and total uncertainties reduced by a factor ranging from 1.05 to 1.6, depending on p T , allowing for a more precise determination of their p T -integrated cross sections. The results are well described by perturbative QCD calculations. The fragmentation fraction of heavy quarks to strange mesonsmore »