864 research outputs found
Physics at Large Rapidities in Hadrons at LEP2
We compute the order-\as corrections to the total cross section and to jet
rates in 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
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 -boson production at hadron colliders
In this talk we give a short review of forward jets and forward -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 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 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
NLO Higgs boson production plus one and two jets using the POWHEG BOX, MadGraph4 and MCFM
We present a next-to-leading order calculation of Higgs boson production plus
one and two jets via gluon fusion interfaced to shower Monte Carlo programs,
implemented according to the POWHEG method. For this implementation we have
used a new interface of the POWHEG BOX with MadGraph4, that generates the codes
for generic Born and real processes automatically. The virtual corrections have
been taken from the MCFM code. We carry out a simple phenomenological study of
our generators, comparing them among each other and with fixed next-to-leading
order results.Comment: 27 pages, 21 figure
Soft gluons in Higgs plus two jet production
We investigate the effects of an all order QCD resummation of soft gluon
emissions for Higgs boson production in association with two hard jets. We
consider both the gluon-gluon fusion and weak boson fusion processes and show
how to resum a large part of the leading logarithms in the jet veto scale. Our
resummation improves on previous analyses which also aim to include the effects
of multiple soft gluon radiation. In addition we calculate the interference
between weak boson fusion and gluon-gluon fusion and find that it is small.Comment: 15 pages and 5 figure
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