Refine
Document Type
- Article (2)
Language
- English (2)
Has Fulltext
- yes (2)
Is part of the Bibliography
- no (2)
Keywords
Institute
The population size and distribution of Phaethon aethereus on Raso Islet was studied from August to December 2016. In total, 42 biometric measures were collected from 38 adults and four juveniles. No recapture was identified although some individuals were ringed in 2014. The means of biometrics variables obtained for the different body segments and eggs were within the ranges of P. aethereus mesonauta from tropical North Atlantic. The two largest agglomerations of P. aethereus identified on Raso were overlapping colonies of brown boobies Sula leucogaster which allowed the maximum direct count of only 90 individuals. The inaccessibility of some breeding areas conditioned the identification and monitoring of just 117 nests. Thus, we estimate the population by the number of nests in more than 100 pairs. However, without an annual census, it is difficult to estimate the population size of this species. So, annual studies are recommended to better understand the population dynamics of P. aethereus on Raso.
The ALICE experiment at the LHC has studied J/psi production at mid-rapidity in pp collisions at sqrt{s}=7 TeV through its electron pair decay on a data sample corresponding to an integrated luminosity L_int = 5.6nb-1. The fraction of J/psi from the decay of long-lived beauty hadrons was determined for J/psi candidates with transverse momentum p_t>1.3 GeV/c and rapidity |y|<0.9. The cross section for prompt J/psi mesons, i.e. directly produced J/psi and prompt decays of heavier charmonium states such as the Psi(2S) and Csi_c resonances, is sigma_prompt-J/psi(pt > 1.3 GeV/c, |y| < 0.9) = 8.3 +- 0.8(stat.) +- 1.1(syst.) + 1.5 - 1.4(syst. pol.) micro barn. The cross section for the production of b-hadrons decaying to J/psi with p_t>1.3 GeV/c and |y|<0.9 is sigma_{J/psi<-h_B} = 1.46 +- 0.38(stat.) + 0.26 -0.32(syst.) micro barn. The results are compared to QCD model predictions. The shape of the p_t and y distributions of b-quarks predicted by perturbative QCD model calculations are used to extrapolate the measured cross section to derive the b-bbar pair total cross section and dsigma/dy at mid-rapidity.