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Search for the radiative $${\Xi}_b^{-}$$ → Ξ−γ decay
A bstract The first search for the rare radiative decay $${\Xi}_b^{-}$$ Ξ b − → Ξ − γ is performed using data collected by the LHCb experiment in proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 fb − 1 . The $${\Xi}_b^{-}$$ Ξ b − → Ξ − J/ψ channel is used as normalization. No $${\Xi}_b^{-}$$ Ξ b − → Ξ − γ signal is found and an upper limit of $$\mathcal{B}$$ B ( $${\Xi}_b^{-}$$ Ξ b − → Ξ − γ ) < 1 . 3 × 10 − 4 at 95% confidence level is obtained.
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Award ID(s):
Publication Date:
NSF-PAR ID:
10343952
Journal Name:
Journal of High Energy Physics
Volume:
2022
Issue:
1
ISSN:
1029-8479
1. 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 »
2. A bstract Using a data sample of 980 fb − 1 collected with the Belle detector at the KEKB asymmetric-energy e + e − collider, we study the processes of $${\Xi}_c^0\to \Lambda {\overline{K}}^{\ast 0}$$ Ξ c 0 → Λ K ¯ ∗ 0 , $${\Xi}_c^0\to {\Sigma}^0{\overline{K}}^{\ast 0}$$ Ξ c 0 → Σ 0 K ¯ ∗ 0 , and $${\Xi}_c^0\to {\Sigma}^{+}{K}^{\ast -}$$ Ξ c 0 → Σ + K ∗ − for the first time. The relative branching ratios to the normalization mode of $${\Xi}_c^0\to {\Xi}^{-}{\pi}^{+}$$ Ξ c 0 → Ξ − π + are measured to be $${\displaystyle \begin{array}{c}\mathcal{B}\left({\Xi}_c^0\to \Lambda {\overline{K}}^{\ast 0}\right)/\mathcal{B}\left({\Xi}_c^0\to {\Xi}^{-}{\pi}^{+}\right)=0.18\pm 0.02\left(\mathrm{stat}.\right)\pm 0.01\left(\mathrm{syst}.\right),\\ {}\mathcal{B}\left({\Xi}_c^0\to {\Sigma}^0{\overline{K}}^{\ast 0}\right)/\mathcal{B}\left({\Xi}_c^0\to {\Xi}^{-}{\pi}^{+}\right)=0.69\pm 0.03\left(\mathrm{stat}.\right)\pm 0.03\left(\mathrm{syst}.\right),\\ {}\mathcal{B}\left({\Xi}_c^0\to {\Sigma}^{+}{K}^{\ast -}\right)/\mathcal{B}\left({\Xi}_c^0\to {\Xi}^{-}{\pi}^{+}\right)=0.34\pm 0.06\left(\mathrm{stat}.\right)\pm 0.02\left(\mathrm{syst}.\right),\end{array}}$$ B Ξ c 0 → Λ K ¯ ∗ 0 / B Ξ c 0 → Ξ − π + = 0.18 ± 0.02 stat . ± 0.01 syst . , B Ξ c 0 → Σ 0 K ¯ ∗ 0 / B Ξ c 0 → Ξ − π + = 0.69 ± 0.03 stat . ± 0.03 syst . , B Ξ c 0 → Σ + K ∗more »
3. Abstract A search for the doubly charmed baryon Ω cc + with the decay mode Ω cc + → Ξ c + K − π + is performed using proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the LHCb experiment from 2016 to 2018, corresponding to an integrated luminosity of 5.4 fb −1 . No significant signal is observed within the invariant mass range of 3.6 to 4.0GeV/ c 2 . Upper limits are set on the ratio R of the production cross-section times the total branching fraction of the Ω cc + → Ξ c + K − π + decay with respect to the $$\Xi _{cc}^{ + + } \to \Lambda _c^ + {K^ - }{\pi ^ + }{\pi ^ + }$$ Ξ c c + + → Λ c + K − π + π + decay. Upper limits at 95% credibility level for R in the range 0.005 to 0.11 are obtained for different hypotheses on the Ω cc + mass and lifetime in the rapidity range from 2.0 to 4.5 and transverse momentum range from 4 to 15 GeV/ c .
4. A bstract The $${\varXi}_{cc}^{++}\to {\varXi}_c^{\prime +}{\pi}^{+}$$ Ξ cc + + → Ξ c ′ + π + decay is observed using proton-proton collisions collected by the LHCb experiment at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5 . 4 fb − 1. The $${\varXi}_{cc}^{++}\to {\varXi}_c^{\prime +}{\pi}^{+}$$ Ξ cc + + → Ξ c ′ + π + decay is reconstructed partially, where the photon from the $${\varXi}_c^{\prime +}\to {\varXi}_c^{+}\gamma$$ Ξ c ′ + → Ξ c + γ decay is not reconstructed and the pK − π + final state of the $${\varXi}_c^{+}$$ Ξ c + baryon is employed. The $${\varXi}_{cc}^{++}\to {\varXi}_c^{\prime +}{\pi}^{+}$$ Ξ cc + + → Ξ c ′ + π + branching fraction relative to that of the $${\varXi}_{cc}^{++}\to {\varXi}_c^{+}{\pi}^{+}$$ Ξ cc + + → Ξ c + π + decay is measured to be 1 . 41 ± 0 . 17 ± 0 . 10, where the first uncertainty is statistical and the second systematic.
5. A bstract This article presents differential measurements of the asymmetry between $${\varLambda}_b^0$$ Λ b 0 and $${\overline{\varLambda}}_b^0$$ Λ ¯ b 0 baryon production rates in proton-proton collisions at centre-of-mass energies of $$\sqrt{s}$$ s = 7 and 8 TeV collected with the LHCb experiment, corresponding to an integrated luminosity of 3 fb − 1 . The $${\varLambda}_b^0$$ Λ b 0 baryons are reconstructed through the inclusive semileptonic decay $${\varLambda}_b^0$$ Λ b 0 → $${\varLambda}_c^{+}$$ Λ c + μ − $$\overline{\nu}$$ ν ¯ μ X . The production asymmetry is measured both in intervals of rapidity in the range 2 . 15 < y < 4 . 10 and transverse momentum in 2 < p T < 27 GeV/ c . The results are found to be incompatible with symmetric production with a significance of 5.8 standard deviations for both $$\sqrt{s}$$ s = 7 and 8 TeV data, assuming no CP violation in the decay. There is evidence for a trend as a function of rapidity with a significance of 4 standard deviations. Comparisons to predictions from hadronisation models in P ythia and heavy-quark recombination aremore »