The production cross sections of D0 and Λ+c hadrons originating from beauty-hadron decays (i.e., nonprompt) were measured for the first time at midrapidity (|y|<0.5) by the ALICE Collaboration in ...proton-proton collisions at a center-of-mass energy √s=13 TeV. They are described within uncertainties by perturbative QCD calculations employing the fragmentation fractions of beauty quarks to baryons measured at forward rapidity by the LHCb Collaboration. The b¯b production cross section per unit of rapidity at midrapidity, estimated from these measurements, is dσb¯b/dy||y|<0.5=83.1±3.5(stat)±5.4(syst)+12.3−3.2(extrap) μb. The baryon-to-meson ratios are computed to investigate the hadronization mechanism of beauty quarks. The nonprompt Λ+c/D0 production ratio has a similar trend to the one measured for the promptly produced charmed particles and to the p/π+ and Λ/K0S ratios, suggesting a similar baryon-formation mechanism among light, strange, charm, and beauty hadrons. The pT -integrated nonprompt Λ+c/D0 ratio is found to be significantly higher than the one measured in e+e− collisions.
Understanding the role of parton mass and Casimir color factors in the quantum chromodynamics parton shower represents an important step in characterizing the emission properties of heavy quarks. ...Recent experimental advances in jet substructure techniques have provided the opportunity to isolate and characterize gluon emissions from heavy quarks. In this Letter, the first direct experimental constraint on the charm-quark splitting function is presented, obtained via the measurement of the groomed shared momentum fraction of the first splitting in charm jets, tagged by a reconstructed D 0 meson. The measurement is made in proton-proton collisions at s=13 TeV , in the low jet transverse-momentum interval of 15≤pTjet ch<30 GeV/c where the emission properties are sensitive to parton mass effects. In addition, the opening angle of the first perturbative emission of the charm quark, as well as the number of perturbative emissions it undergoes, is reported. Comparisons to measurements of an inclusive-jet sample show a steeper splitting function for charm quarks compared with gluons and light quarks. Charm quarks also undergo fewer perturbative emissions in the parton shower, with a reduced probability of large-angle emissions.
The most precise measurements to date of the H Λ 3 lifetime τ and Λ separation energy B Λ are obtained using the data sample of Pb-Pb collisions at sNN=5.02 TeV collected by ALICE at the LHC. The H ...Λ 3 is reconstructed via its charged two-body mesonic decay channel ( H Λ 3 → He3+π- and the charge-conjugate process). The measured values τ= 253±11 ( stat ) ±6 ( syst ) ps and B Λ = 102±63 ( stat ) ±67 ( syst ) keV are compatible with predictions from effective field theories and confirm that the H Λ 3 structure is consistent with a weakly bound system.
Measurement of the Λ hyperon lifetime Aglieri Rinella, G.; Al-Turany, M.; Aleksandrov, D. ...
Physical review. D,
08/2023, Volume:
108, Issue:
3
Journal Article
Peer reviewed
Open access
A new, more precise measurement of the Λ hyperon lifetime is performed using a large data sample of Pb-Pb collisions at $\sqrt{s_{NN}}$=5.02 TeV with ALICE. The Λ and $\bar{Λ}$ hyperons are ...reconstructed at midrapidity using their two-body weak decay channel Λ→p+π- and $\bar{Λ}$→$\bar{p}$+π+. The measured value of the Λ lifetime is τΛ=261.07±0.37(stat.)±0.72(syst.) ps. The relative difference between the lifetime of Λ and $\bar{Λ}$, which represents an important test of CPT invariance in the strangeness sector, is also measured. The obtained value (τΛ-τ$\bar{Λ}$)/τΛ=0.0013±0.0028(stat.)±0.0021(syst.) is consistent with zero within the uncertainties. Both measurements of the Λ hyperon lifetime and of the relative difference between τΛ and τ$\bar{Λ}$ are in agreement with the corresponding world averages of the Particle Data Group and about a factor of three more precise.
The pseudorapidity density of charged particles with minimum transverse momentum (pT) thresholds of 0.15, 0.5, 1, and 2 GeV/c is measured in pp collisions at the center of mass energies of √s=5.02 ...and 13 TeV with the ALICE detector. The study is carried out for inelastic collisions with at least one primary charged particle having a pseudorapidity (η) within ±0.8 and pT larger than the corresponding threshold. In addition, measurements without pT-thresholds are performed for inelastic and nonsingle-diffractive events as well as for inelastic events with at least one charged particle having |η|<1 in pp collisions at √s=5.02 TeV for the first time at the LHC. These measurements are compared to the pythia 6, pythia 8, and epos-lhc models. In general, the models describe the η dependence of particle production well. However, discrepancies are observed for the highest transverse momentum threshold (pT>2 GeV/c), highlighting the importance of such measurements for tuning event generators. The new measurements agree within uncertainties with results from the ATLAS and CMS experiments obtained at √s=13 TeV.
Economic weights (EW) for the Slovak dairy production system were calculated in Holstein, Slovak Simmental, and Slovak Pinzgau breeds under a direct support regime using a bio-economic approach. EW ...were calculated for three scenarios as follows: A: without agricultural subsidies; B: agricultural subsidies included in revenues and C: agricultural subsidies included in feeding costs. Quota-free milk production was assumed in all scenarios. The base price of milk was corrected according to real fat, protein and somatic cell content. Under the given economic and production conditions, only the Holstein system in scenario A was economically profitable. All simulated systems were profit-making when agricultural subsidies were taken into account (B and C). No influence of subsidies on EW of traits in scenario B was found. Most of the evaluated traits (especially milk and functional traits) showed higher marginal economic weights when subsidies were considered in feeding costs (C). Regardless of the scenarios, milk components were of higher relative economic importance for Holstein cattle than for Slovak Simmental and Slovak Pinzgau cattle. The relative EW of mature weight of cows and daily gain of calves mostly declined in scenario C. A meaningful effect of direct subsidy and milk production level on the economic efficiency of Slovak Simmental and Slovak Pinzgau cattle was found. Handling direct subsidy in scenario C seems to be a suitable methodology to avoid the underestimation of EW for milk and functional traits.
The aim of this prospective study on fungemia in children with cancer compared with adults with cancer appearing during the last 10 years in a pediatric hospital and in national cancer institutions ...was to investigate risk factors, etiology, therapy, complications and outcome. Univariate analysis showed significant differences in 35 children with cancer and fungemia in comparison with 130 cases of fungemias in adults with cancer. It was found that (1) therapy with corticosteroids (40 vs 18.5%, P<0.03), (2) breakthrough fungemia during ketoconazole prophylaxis (20 vs 7.7%, P<0.025), and (3) meningitis as a complication of fungemia (11.4 vs 0.8%, P< 0.001) occurred more frequently in the pediatric subgroup with fungemia. Candida albicans was more common as the causative agent of fungemia among adults (58.5 vs 37.1, P<0.02) than in children. However, mortality was similar in children with cancer and in adults with cancer and fungemia (31.4 vs 23.1%, NS). Comparison of risk factors revealed no differences between adults and children with cancer and fungemia except in etiology, breakthrough fungemia during prophylaxis with ketoconazole, prior therapy with corticosteroids and meningitis as a complication. The outcome was also similar in pediatric and adult cancer patients with fungal bloodstream infection.
PDF
