Physics at Large Rapidities in γ∗γ∗→\gamma^*\gamma^* \to Hadrons at LEP2

We compute the order-\as corrections to the total cross section and to jet rates in $\gamma^* \gamma^* \to$ hadrons for the process \epem\to\epem + hadrons. We use a NLO order general-purpose partonic Monte Carlo event generator that allows the computation of a rate differential in the produced leptons and hadrons. We compare our results with the experimental data for \epem\to\epem + hadrons at LEP2.Comment: 5 pages, 1 figure, presented at the LEPTRE meeting, Roma 200

Kinematical Limits on Higgs Boson Production via Gluon Fusion in Association with Jets

In this paper, we analyze the high-energy limits for Higgs boson plus two jet production. We consider two high-energy limits, corresponding to two different kinematic regions: a) the Higgs boson is centrally located in rapidity between the two jets, and very far from either jet; b) the Higgs boson is close to one jet in rapidity, and both of these are very far from the other jet. In both cases the amplitudes factorize into impact factors or coefficient functions connected by gluons exchanged in the t channel. Accordingly, we compute the coefficient function for the production of a Higgs boson from two off-shell gluons, and the impact factors for the production of a Higgs boson in association with a gluon or a quark jet. We include the full top quark mass dependence and compare this with the result obtained in the large top-mass limit.Comment: 35 pages, 6 figure

Editorial: Regulation of pollen tube growth, volume II

The pollen tube is an extension produced by the pollen grain when conditions are favorable; thus, the pollen tube is important in seed plant reproduction because it transports male gametes. However, it is also an excellent system for studying various plant cell processes that are common to sink organs or tissues (Kroeger and Geitmann, 2012). The pollen tube has been used to study a variety of processes, including vesicular transport, cytoskeletal organization, cell wall deposition, ion gradients, intracellular signaling. Since the pollen tube grows by contacting and signaling to pistil cells, it is also a model for studying cell-cell communication (Broz and Bedinger, 2021). Moreover, the pollen tube is involved in self-incompatibility (SI) processes that regulate reproduction and thus promote hybridization and genetic variability (Mandrone et al., 2019). SI is regulated by several factors, and in some cases, such as citrus, it is an important tool for producing seedless mandarins (Gentile et al., 2012). Pollen tube and pollen can also be targets of environmental stresses (Ledesma and Sugiyama, 2019), which can impair plant reproductive success, resulting in lower productivity of agronomically important plants and increasing allergenicity (pollinosis) (Armentia et al., 2019; Singh and Mathur, 2021)

Editorial: Regulation of Pollen Tube Growth

In angiosperms, the pollen tube is a simple system composed of the vegetative cell and the two sperm cells which, nevertheless, accomplishes a very important process, essential for the life of flowering plants on Earth, i.e., sexual reproduction. In its simplicity, the pollen tube allowed plants to reproduce on land, even in the absence of water. Therefore, it is a very critical evolutionary factor. In the last 30 years, the pollen tube has been the object of study for many researchers around the world because of a number of reasons; apart from its biological importance, the pollen tube is a highly valuable cell model by which to analyze many aspects of plant cell biology (except for photosynthesis). The time course of cell wall deposition, the role of calcium ions in driving the apical growth of pollen tube, the action of signal transduction intermediates, the cell-cell communication, the mechanism of cell shape control by exocytosis/endocytosis are just some of the aspects on which it is possible to find articles in the scientific literature dealing with the pollen tube. Not to forget that the study of pollen tubes also has practical implications because the control of the reproductive process of plants also involves the study of genes, proteins and metabolites that promote or prevent the growth of pollen tubes. Therefore, controlling pollen tube growth can impact seed and fruit yields. Due to all these considerations, the Research Topic “Regulation of pollen tube growth” was meant to highlight some of the above aspects with updated considerations and special focus. These include contributions related to human health, pollen-pistil interaction, the growth of pollen tubes by exocytosis/endocytosis, and the rejection of the pollen tube in self-incompatibility processe

Dijet Production at Hadron--Hadron Colliders in the BFKL Approach

The production in high-energy hadron collisions of a pair of jets with large rapidity separation is studied in an improved BFKL formalism. By recasting the analytic solution of the BFKL equation as an explicit order-by-order sum over emitted gluons, the effects of phase space constraints and the running coupling are studied. Particular attention is paid to the azimuthal angle decorrelation of the jet pair. The inclusion of sub-leading effects significantly improves the agreement between the theoretical predictions and recent preliminary measurements from the Dzero collaboration.Comment: 19 pages LaTeX; one figure corrected; conclusions unchange

Forward jets and forward WW-boson production at hadron colliders

In this talk we give a short review of forward jets and forward $W$-boson production at hadron colliders, in view of the extraction of footprints of BFKL physics. We argue that at Tevatron energies, dijet production at large rapidity intervals is still subasymptotic with respect to the BFKL regime, thus the cross section is strongly dependent on the various cuts applied in the experimental setup. In addition, the choice of equal transverse momentum cuts on the tagging jets makes the cross section dependent on large logarithms of non-BFKL origin, and thus may spoil the BFKL analysis. For vector boson production in association with two jets, we argue that the configurations that are kinematically favoured tend to have the vector boson forward in rapidity. Thus $W + 2$ jet production lends itself naturally to extensions to the high-energy limit.Comment: LaTeX, JHEP style, 10 pages, 3 figures. Based on a talk at EPS2001, Budapest, Hungar

Hopf algebras, coproducts and symbols: an application to Higgs boson amplitudes

We show how the Hopf algebra structure of multiple polylogarithms can be used to simplify complicated expressions for multi-loop amplitudes in perturbative quantum field theory and we argue that, unlike the recently popularized symbol-based approach, the coproduct incorporates information about the zeta values. We illustrate our approach by rewriting the two-loop helicity amplitudes for a Higgs boson plus three gluons in a simplified and compact form involving only classical polylogarithms.Comment: 46 page

Virtual Next-to-Leading Corrections to the Lipatov Vertex

We compute the virtual next-to-leading corrections to the Lipatov vertex in the helicity-amplitude formalism. These agree with previous results by Fadin and collaborators, in the conventional dimensional-regularization scheme. We discuss the choice of reggeization scale in order to minimize its impact on the next-to-leading-logarithmic corrections to the BFKL equation.Comment: Latex, 20 pages, no figures; One minor typo fixed. References added. To be published in Phys. Rev.

QCD radiative corrections to γ∗γ∗→\gamma^*\gamma^* \to hadrons

We compute the order-\as corrections to the total cross section and to jet rates for the process \epem\to\epem + hadrons, where the hadrons are produced through crossed-channel quark exchange in the hard scattering of two off-shell photons originating from the incoming leptons. We use a next-to-leading order general-purpose partonic Monte Carlo event generator that allows the computation of a rate differential in the produced leptons and hadrons. We compare our results with the available experimental data for \epem\to\epem + hadrons at LEP2.Comment: 25 pages Latex; 1 style file and 14 figures include

Small Grains in Cropping Systems to the Brazilian Southern Regions

Winter cereals genotypes (oats, wheat, rye, barley, and triticale) were evaluated for forage and grain yield at the experimental area of the Wheat National Research Center (EMBRAPA/CNPT) and Agronomy College of the Universidade de Passo Fundo (UPF/FA), in Passo Fundo, RS state, southern Brazil, during the years 1992-94. Three cutting frequencies were applied: no cutting, one and two cuttings. A completely random block design with split-plots and three replicates was used. The crops were established under conventional tillage. The fertilization was 200- 300 kg/ha 5-25-25 , plus 22.5-30.0 kg/ha of N (urea) during tiller period (before 45 days after planting date). The cereals were planted on May 3-17, by hand, using 60-100 seeds/m in rows spaced 0.2m apart. The forage was cut by hand when the plants had approximately 30 cm of height at 7 cm of the soil level. Dry matter yield, grain yield, crude protein yield, and crude protein content were determined. The rye BR 1 showed the best performance for forage, and crude protein yield. Hectoliter weight, density, and emergence-flowering period were determined. The rye BR 1 showed the best performance for forage and crude protein yield, whereas oats UPF 15 was outstanding for grain yield. In addition, triticale BR 4, wheat IPF 55204, and PF 87451, and oats UPF 13, UPF 14, CTC 2, and UFRGS 12 were promising for double purpose, early grazing and harvest