Angular correlations between unidentified charged trigger particles and various species of charged associated particles (unidentified particles, pions, kaons, protons and antiprotons) are measured by ...the ALICE detector in p–Pb collisions at a nucleon–nucleon centre-of-mass energy of 5.02 TeV in the transverse-momentum range 0.3<pT<4 GeV/c. The correlations expressed as associated yield per trigger particle are obtained in the pseudorapidity range |ηlab|<0.8. Fourier coefficients are extracted from the long-range correlations projected onto the azimuthal angle difference and studied as a function of pT and in intervals of event multiplicity. In high-multiplicity events, the second-order coefficient for protons, v2p, is observed to be smaller than that for pions, v2π, up to about pT=2 GeV/c. To reduce correlations due to jets, the per-trigger yield measured in low-multiplicity events is subtracted from that in high-multiplicity events. A two-ridge structure is obtained for all particle species. The Fourier decomposition of this structure shows that the second-order coefficients for pions and kaons are similar. The v2p is found to be smaller at low pT and larger at higher pT than v2π, with a crossing occurring at about 2 GeV/c. This is qualitatively similar to the elliptic-flow pattern observed in heavy-ion collisions. A mass ordering effect at low transverse momenta is consistent with expectations from hydrodynamic model calculations assuming a collectively expanding system.
Exclusive ρ0-meson electroproduction is studied by the HERMES experiment, using the 27.6 GeV longitudinally polarized electron/positron beam of HERA and a transversely polarized hydrogen target, in ...the kinematic region 1.0 GeV2<Q2< 7.0 GeV2, 3.0 GeV <W< 6.3 GeV, and -t′< 0.4 GeV2. Using an unbinned maximum-likelihood method, 25 parameters are extracted. These determine the real and imaginary parts of the ratios of several helicity amplitudes describing ρ0-meson production by a virtual photon. The denominator of those ratios is the dominant amplitude, the nucleon-helicity-non-flip amplitude F012012, which describes the production of a longitudinal ρ0-meson by a longitudinal virtual photon. The ratios of nucleon-helicity-non-flip amplitudes are found to be in good agreement with those from the previous HERMES analysis. The transverse target polarization allows for the first time the extraction of ratios of a number of nucleon-helicity-flip amplitudes to F012012. Results obtained in a handbag approach based on generalized parton distributions taking into account the contribution from pion exchange are found to be in good agreement with these ratios. Within the model, the data favor a positive sign for the π-ρ transition form factor. By also exploiting the longitudinal beam polarization, a total of 71 ρ0 spin-density matrix elements is determined from the extracted 25 parameters, in contrast to only 53 elements as directly determined in earlier analyses.
Abstract Exclusive $$\rho ^0$$ ρ 0 -meson electroproduction is studied by the HERMES experiment, using the 27.6 GeV longitudinally polarized electron/positron beam of HERA and a transversely ...polarized hydrogen target, in the kinematic region 1.0 GeV $$^2<Q^2<$$ 2 < Q 2 < 7.0 GeV $$^2$$ 2 , 3.0 GeV $$<W<$$ < W < 6.3 GeV, and $$-t^\prime <$$ - t ′ < 0.4 GeV $$^2$$ 2 . Using an unbinned maximum-likelihood method, 25 parameters are extracted. These determine the real and imaginary parts of the ratios of several helicity amplitudes describing $$\rho ^{0}$$ ρ 0 -meson production by a virtual photon. The denominator of those ratios is the dominant amplitude, the nucleon-helicity-non-flip amplitude $$F_{0\frac{1}{2}0\frac{1}{2}}$$ F 0 1 2 0 1 2 , which describes the production of a longitudinal $$\rho ^{0}$$ ρ 0 -meson by a longitudinal virtual photon. The ratios of nucleon-helicity-non-flip amplitudes are found to be in good agreement with those from the previous HERMES analysis. The transverse target polarization allows for the first time the extraction of ratios of a number of nucleon-helicity-flip amplitudes to $$F_{0\frac{1}{2}0\frac{1}{2}}$$ F 0 1 2 0 1 2 . Results obtained in a handbag approach based on generalized parton distributions taking into account the contribution from pion exchange are found to be in good agreement with these ratios. Within the model, the data favor a positive sign for the $$\pi -\rho $$ π - ρ transition form factor. By also exploiting the longitudinal beam polarization, a total of 71 $$\rho ^0$$ ρ 0 spin-density matrix elements is determined from the extracted 25 parameters, in contrast to only 53 elements as directly determined in earlier analyses.
A measurement of beam-helicity asymmetries for single-hadron production in deep-inelastic scattering is presented. Data from the scattering of 27.6 GeV electrons and positrons off gaseous hydrogen ...and deuterium targets were collected by the HERMES experiment. The asymmetries are presented separately as a function of the Bjorken scaling variable, the hadron transverse momentum, and the fractional energy for charged pions and kaons as well as for protons and anti-protons. These asymmetries are also presented as a function of the three aforementioned kinematic variables simultaneously.
The inclusive transverse momentum (pT) distributions of primary charged particles are measured in the pseudo-rapidity range |η|<0.8 as a function of event centrality in Pb–Pb collisions at ...sNN=2.76 TeV with ALICE at the LHC. The data are presented in the pT range 0.15<pT<50 GeV/c for nine centrality intervals from 70–80% to 0–5%. The results in Pb–Pb are presented in terms of the nuclear modification factor RAA using a pp reference spectrum measured at the same collision energy. We observe that the suppression of high-pT particles strongly depends on event centrality. The yield is most suppressed in central collisions (0–5%) with RAA≈0.13 at pT=6–7 GeV/c. Above pT=7 GeV/c, there is a significant rise in the nuclear modification factor, which reaches RAA≈0.4 for pT>30 GeV/c. In peripheral collisions (70–80%), only moderate suppression (RAA=0.6–0.7) and a weak pT dependence is observed. The measured nuclear modification factors are compared to other measurements and model calculations.
Inclusive transverse momentum spectra of primary charged particles in Pb–Pb collisions at sNN=2.76 TeV have been measured by the ALICE Collaboration at the LHC. The data are presented for central and ...peripheral collisions, corresponding to 0–5% and 70–80% of the hadronic Pb–Pb cross section. The measured charged particle spectra in |η|<0.8 and 0.3<pT<20 GeV/c are compared to the expectation in pp collisions at the same sNN, scaled by the number of underlying nucleon–nucleon collisions. The comparison is expressed in terms of the nuclear modification factor RAA. The result indicates only weak medium effects (RAA≈0.7) in peripheral collisions. In central collisions, RAA reaches a minimum of about 0.14 at pT=6–7 GeV/c and increases significantly at larger pT. The measured suppression of high-pT particles is stronger than that observed at lower collision energies, indicating that a very dense medium is formed in central Pb–Pb collisions at the LHC.
Introduction
Three
in vitro
experiments were conducted to evaluate the effects of increasing levels of Enterococcus faecium and Saccharomyces cerevisiae (DFM1) and increasing levels of Bacillus ...licheniformis and Bacillus subtilis (DFM2) on
in vitro
ruminal fermentation parameters in three different dietary scenarios.
Methods
For Exp. 1, the basal diet consisted of 25:75 roughage:concentrate ratio (R:C) and was composed by 5 treatments: control (no additive), 2 levels of DFM1 (1X = 1.9 mg and 5X = 9.0 mg), and 2 levels of DFM2 (1X = 3.8 mg and 5X = 19 mg). The Exp. 2 consisted of a 41:59 R:C diet and was composed by 5 treatments: control (no additive) and 2 levels of DFM1 (1X = 3.8 mg and 5 X = 19 mg) and 2 levels of DFM2 (1X = 5.6 mg and 5X = 28 mg). The Exp. 3 consisted of a 100:0 R:C diet Brachiaria (syn. Urochloa brizantha) and was composed by the same treatments described in Exp. 1. The DFM1 contained 3.5 × 109 CFU per g of Enterococccus faecium and Saccharomyces cerevisiae, whereas the DFM2 contained Bacillus licheniformis and Bacillus subtilis at 3.2 × 109 CFU per g. In each Exp., an
in vitro
gas production (GP) system with 43-bottles (AnkomRF) was used in four consecutive 48 or 72-h fermentation batches to evaluate total GP (TGP), kinetics and fermentation profiles, methane (CH4), and carbon dioxide (CO2).
Results
For Exp 1, DFM1 increased quadratically TGP at 24 and 48-h, which reflected in a greater
in vitro
organic matter digestibility (IVOMD). The concentrations of ammonia-N, CH4, and CO2 (mmol/g of IVOMD) reduced quadratically as DFM1 increased. For Exp. 2, DFM1 inclusion reduced butyrate concentration and acetate to propionate ratio. Regarding GHG emissions, DFM1 and DFM2 quadratically reduced CH4 and CO2 emission per IVOMD (mmol/g of IVOMD). For Exp. 3, DFM1 increased quadratically TGP at 48h with no impact on IVOMD. Otherwise, DFM2 increased linearly TGP at 24 and 48h which reflected in a greater IVOMD. The inclusion of DFM1 increased linearly iso-valerate and branched-chain volatile fatty acids (BCVFA) concentration and DFM2 addition increased BCVFA quadratically.
Discussion
Overall, addition of DFM1 Enterococccus faecium (5 × 109 CFU per g) + Saccharomyces cerevisiae (5 × 109 CFU per g) or DFM2 Bacillus licheniformis + Bacillus subtilis (3.2 × 109 CFU per g) might enhance the fermentation process in the rumen and decrease greenhouse gas emissions in a dose-dependent manner, though the results are contingent on the specific type of diet.
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