Midrapidity hyperon production in pp and pA collisions from low to LHC energies

The experimental data on p, Lambda, Xi-, Omega-, baryons and the corresponding antibaryons spectra obtained by different collaborations are compared with the results of the calculations performed into the frame of the Quark-Gluon String Model. The contribution of String Junction diffusion and the inelastic screening corrections are accounted for in the theoretical calculations. The predictions of the Quark-Gluon String Model both for pp and pA collisions are extended up to the LHC energies.Comment: 23 pages, 12 figures, and 3 tables. arXiv admin note: substantial text overlap with arXiv:1305.0388; text overlap with arXiv:1307.3442 by other author

Effects of forage supplements on milk production and chemical properties, in vivo digestibility, rumen fermentation and N excretion in dairy cows offered red clover silage and corn silage or dry ground corn

peer-reviewedThis study concerned the effects of partial substitution of clover silage with high starch forages on milk production and chemical composition, in vivo digestibility, rumen fermentation pattern and nitrogen excretion of dairy cows. Sixteen dairy cows were separated into two groups and were assigned to treatments in a two-period crossover design. Two forage supplements were used: corn silage (CS) and dry ground corn (DG). All animals received 4.5 kg of concentrate dry matter per day. Results showed no significant difference between the forage supplements for milk production, while significant differences (P<0.01) were observed for milk fat, milk protein and nitrogen utilisation efficiency (42 v. 4.0 g/kg, 3.5 v. 3.3 g/kg and 222 v. 188 g/kg, respectively, for DG and CS). Faecal N excretion did not differ between forage supplements, but urinary N excretion was higher for CS (P<0.05). No significant differences were observed between treatments for rumen fluid pH or for rumen fluid concentrations of ammonium nitrogen or of acetic, propionic or butyric acids. Dry matter intake and the in vivo digestibility of dry matter, organic matter, acid detergent fibre and neutral detergent fibre were all higher for CS compared with DG.The authors are grateful to the Environmental Office of the Cantabrian Government for funding the project 05-640.02-2174

Complementary views on electron spectra: From Fluctuation Diagnostics to real space correlations

We study the relation between the microscopic properties of a many-body system and the electron spectra, experimentally accessible by photoemission. In a recent paper [Phys. Rev. Lett. 114, 236402 (2015)], we introduced the "fluctuation diagnostics" approach, to extract the dominant wave vector dependent bosonic fluctuations from the electronic self-energy. Here, we first reformulate the theory in terms of fermionic modes, to render its connection with resonance valence bond (RVB) fluctuations more transparent. Secondly, by using a large-U expansion, where U is the Coulomb interaction, we relate the fluctuations to real space correlations. Therefore, it becomes possible to study how electron spectra are related to charge, spin, superconductivity and RVB-like real space correlations, broadening the analysis of an earlier work [Phys. Rev. B 89, 245130 (2014)]. This formalism is applied to the pseudogap physics of the two-dimensional Hubbard model, studied in the dynamical cluster approximation. We perform calculations for embedded clusters with up to 32 sites, having three inequivalent K-points at the Fermi surface. We find that as U is increased, correlation functions gradually attain values consistent with an RVB state. This first happens for correlation functions involving the antinodal point and gradually spreads to the nodal point along the Fermi surface. Simultaneously a pseudogap opens up along the Fermi surface. We relate this to a crossover from a Kondo-like state to an RVB-like localized cluster state and to the presence of RVB and spin fluctuations. These changes are caused by a strong momentum dependence in the cluster bath-couplings along the Fermi surface. We also show, from a more algorithmic perspective, how the time-consuming calculations in fluctuation diagnostics can be drastically simplified.Comment: 19 pages, 8 figure

Parquet decomposition calculations of the electronic self-energy

The parquet decomposition of the self-energy into classes of diagrams, those associated with specific scattering processes, can be exploited for different scopes. In this work, the parquet decomposition is used to unravel the underlying physics of non-perturbative numerical calculations. We show the specific example of dynamical mean field theory (DMFT) and its cluster extensions (DCA) applied to the Hubbard model at half-filling and with hole doping: These techniques allow for a simultaneous determination of two-particle vertex functions and self-energies, and hence, for an essentially "exact" parquet decomposition at the single-site or at the cluster level. Our calculations show that the self-energies in the underdoped regime are dominated by spin scattering processes, consistent with the conclusions obtained by means of the fluctuation diagnostics approach [Phys. Rev. Lett. 114, 236402 (2015)]. However, differently from the latter approach, the parquet procedure displays important changes with increasing interaction: Even for relatively moderate couplings, well before the Mott transition, singularities appear in different terms, with the notable exception of the predominant spin-channel. We explain precisely how these singularities, which partly limit the utility of the parquet decomposition, and - more generally - of parquet-based algorithms, are never found in the fluctuation diagnostics procedure. Finally, by a more refined analysis, we link the occurrence of the parquet singularities in our calculations to a progressive suppression of charge fluctuations and the formation of an RVB state, which are typical hallmarks of a pseudogap state in DCA.Comment: 19 pages, 16 figure

Hadroproduction of neutral Kstar-mesons up to LHC energies

We consider the experimental data on neutral Kstar-meson production on nucleon and nuclear targets. The Quark-Gluon String Model quantitatively describes the inclusive density in the midrapidity region, as well as the initial energy and A dependences of the produced Kstar-mesons.Comment: 19 pages, 8 figures, and 4 tables. arXiv admin note: text overlap with arXiv:1610.0603