Study of the B−→Λc+Λˉc−K−B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-} decay

The decay $B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-}$ is studied in proton-proton collisions at a center-of-mass energy of $\sqrt{s}=13$ TeV using data corresponding to an integrated luminosity of 5 $\mathrm{fb}^{-1}$ collected by the LHCb experiment. In the $\Lambda_{c}^+ K^{-}$ system, the $\Xi_{c}(2930)^{0}$ state observed at the BaBar and Belle experiments is resolved into two narrower states, $\Xi_{c}(2923)^{0}$ and $\Xi_{c}(2939)^{0}$, whose masses and widths are measured to be $$m(\Xi_{c}(2923)^{0}) = 2924.5 \pm 0.4 \pm 1.1 \,\mathrm{MeV}, \\ m(\Xi_{c}(2939)^{0}) = 2938.5 \pm 0.9 \pm 2.3 \,\mathrm{MeV}, \\ \Gamma(\Xi_{c}(2923)^{0}) = \phantom{000}4.8 \pm 0.9 \pm 1.5 \,\mathrm{MeV},\\ \Gamma(\Xi_{c}(2939)^{0}) = \phantom{00}11.0 \pm 1.9 \pm 7.5 \,\mathrm{MeV},$$ where the first uncertainties are statistical and the second systematic. The results are consistent with a previous LHCb measurement using a prompt $\Lambda_{c}^{+} K^{-}$ sample. Evidence of a new $\Xi_{c}(2880)^{0}$ state is found with a local significance of $3.8\,\sigma$, whose mass and width are measured to be $2881.8 \pm 3.1 \pm 8.5\,\mathrm{MeV}$ and $12.4 \pm 5.3 \pm 5.8 \,\mathrm{MeV}$, respectively. In addition, evidence of a new decay mode $\Xi_{c}(2790)^{0} \to \Lambda_{c}^{+} K^{-}$ is found with a significance of $3.7\,\sigma$. The relative branching fraction of $B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-}$ with respect to the $B^{-} \to D^{+} D^{-} K^{-}$ decay is measured to be $2.36 \pm 0.11 \pm 0.22 \pm 0.25$, where the first uncertainty is statistical, the second systematic and the third originates from the branching fractions of charm hadron decays.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-028.html (LHCb public pages

Multidifferential study of identified charged hadron distributions in ZZ-tagged jets in proton-proton collisions at s=\sqrt{s}=13 TeV

Jet fragmentation functions are measured for the first time in proton-proton collisions for charged pions, kaons, and protons within jets recoiling against a $Z$ boson. The charged-hadron distributions are studied longitudinally and transversely to the jet direction for jets with transverse momentum 20 $< p_{\textrm{T}} < 100$ GeV and in the pseudorapidity range $2.5 < \eta < 4$. The data sample was collected with the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.64 fb$^{-1}$. Triple differential distributions as a function of the hadron longitudinal momentum fraction, hadron transverse momentum, and jet transverse momentum are also measured for the first time. This helps constrain transverse-momentum-dependent fragmentation functions. Differences in the shapes and magnitudes of the measured distributions for the different hadron species provide insights into the hadronization process for jets predominantly initiated by light quarks.Comment: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-013.html (LHCb public pages

Measurement of the ratios of branching fractions R(D∗)\mathcal{R}(D^{*}) and R(D0)\mathcal{R}(D^{0})

The ratios of branching fractions $\mathcal{R}(D^{*})\equiv\mathcal{B}(\bar{B}\to D^{*}\tau^{-}\bar{\nu}_{\tau})/\mathcal{B}(\bar{B}\to D^{*}\mu^{-}\bar{\nu}_{\mu})$ and $\mathcal{R}(D^{0})\equiv\mathcal{B}(B^{-}\to D^{0}\tau^{-}\bar{\nu}_{\tau})/\mathcal{B}(B^{-}\to D^{0}\mu^{-}\bar{\nu}_{\mu})$ are measured, assuming isospin symmetry, using a sample of proton-proton collision data corresponding to 3.0 fb${ }^{-1}$ of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode $\tau^{-}\to\mu^{-}\nu_{\tau}\bar{\nu}_{\mu}$. The measured values are $\mathcal{R}(D^{*})=0.281\pm0.018\pm0.024$ and $\mathcal{R}(D^{0})=0.441\pm0.060\pm0.066$, where the first uncertainty is statistical and the second is systematic. The correlation between these measurements is $\rho=-0.43$. Results are consistent with the current average of these quantities and are at a combined 1.9 standard deviations from the predictions based on lepton flavor universality in the Standard Model.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-039.html (LHCb public pages

First observation of the Λ0 b → Λ+ c D− s K+K− decay and search for pentaquarks in the Λ+ c D− s system

The Λ0 b → Λþ c D− s KþK− decay is observed for the first time using the data sample from proton-proton collisions recorded at a center-of-mass energy of 13 TeV with the LHCb detector, corresponding to an integrated luminosity of 6 fb−1. The ratio of branching fraction to that of Λ0 b → Λþ c D− s decays is measured as 0.0141 0.0019 0.0012, where the first uncertainty is statistical and the second systematic. A search for hidden-charm pentaquarks with strangeness is performed in the Λþ c D− s system. No evidence is found, and upper limits on the production ratio of Pccs¯ ð4338Þ0 and Pccs¯ ð4459Þ0 pentaquarks relative to the Λþ c D− s final state are set at the 95% confidence level as 0.12 and 0.20, respectively

Underestimated diversity: A new species of the genus Cuneopsis (Bivalvia, Unionidae, Unioninae) from Henan, China

The global decline of freshwater mussels and their crucial ecological services highlights the necessity and urgency of developing and guiding conservation efforts for this group. Accurately delineating species and understanding their phylogeny are crucial to the core of species conservation. Here, we integrate shell morphology, soft-body anatomy, and molecular systematics to describe a new species of freshwater mussel from the Shi River in Xinyang City, Henan Province, China, i.e., Cuneopsis celtiosimilis sp. nov. Morphologically, this new species resembles its congeneric species C. kiangsiensis and C. celtiformis in shell size, shape, and sculpture. However, this new species can be distinguished from closely related congeners by the pseudocardinal teeth. For the new species, two pseudocardinal teeth of the left valve join together to form a continuous strip; the single pseudocardinal tooth on the right valve is more squashed and lower; the papillae of the incurrent aperture are shorter, forming a pyramidal shape and arranged in two rows. Molecularly, based on the mitochondrial barcoding gene cytochrome c oxidase subunit I (COI), the minimum genetic distance between the new species and other known congeners is 4.6% (C. celtiosimilis sp. nov. vs. C. kiangsiensis). Additionally, the complete mitogenome of C. celtiosimilis sp. nov. was also assembled and annotated. Based on the mitochondrial phylogenomic analyses, the results clarify the phylogenetic position of the new species and establish the most comprehensive phylogenetic relationship of the genus Cuneopsis to date, as follows: ((((C. demangei + C. heudei) + C. szechenyii) + ((C. kiangsiensis + C. celtiosimilis sp. nov.) + C. celtiformis)) + C. rufescens). The discovery of this new taxon contributes to the existing knowledge on freshwater mussels in China, and a key to all known species of Cuneopsis is provided to aid the identification of species in this understudied genus

Revisiting the genus Nodularia (Bivalvia, Unionidae): Mitochondrial phylogenomics and the description of a new species

The genus Nodularia poses a significant challenge to traditional species classification and identification due to its highly convergent and variable shells, rendering it one of the most intricate groups within the family Unionidae. Fortunately, significant progress has been made by researchers in recent years regarding the species validity and the phylogeny of this group based on molecular data. However, the inadequate exploration of regional constraints and inherent limitations in research methodologies remains a crucial factor contributing to the underestimation of species diversity. In this study, a new species of freshwater mussel from the Qingshui River in Nanning City, Guangxi Province, China, Nodularia guiensis sp. nov., is described based on shell morphology, anatomical characters, and molecular phylogenetics. Mitochondrial phylogenomic analyses reveal the following phylogenetic relationships: (((Nodularia hanensis + Nodularia micheloti) + Nodularia dorri) + (Nodularia breviconcha + (Nodularia huana + (Nodularia fusiformans + (Nodularia guiensis sp. nov. + ((Nodularia nuxpersicae + Nodularia nipponensis) + (Nodularia dualobtusus + Nodularia douglasiae))))))). The discovery of this new taxon further enhances the diversity level within the genus Nodularia in China and also highlights the necessity for comprehensive surveys of unexplored regions in order to potentially unveil additional new taxa in the future

Addition to the known diversity of Chinese freshwater mussels: integrative description of a new species of Postolata Dai et al., 2023 (Bivalvia, Unionidae, Gonideinae)

In this study, we present a new species of freshwater mussel in the genus Postolata Dai et al., 2023, from Guangxi Province, China, by integrating morphological, anatomical, and molecular data. Postolata longjiangensis Liu & Wu, sp. nov. is distinguished from its congener (i.e., Postolata guangxiensis) by its shell shape, beak position, surface sculpture, nacre color, and hinge structure. Molecular species delimitation results based on the mitochondrial COI gene support the separation of Postolata longjiangensis Liu & Wu, sp. nov. from its congener. The multi-locus (COI + 16S rRNA + 28S rRNA) phylogeny reveals that this species forms the sister lineage to Postolata guangxiensis in the tribe Gonideini