1,702 research outputs found
NLO Higgs boson production via gluon fusion matched with shower in POWHEG
We present a next-to-leading order calculation of Higgs boson production via
gluon fusion interfaced to shower Monte Carlo programs, implemented according
to the POWHEG method. A detailed comparison with MC@NLO and PYTHIA is carried
out for several observables, for the Tevatron and LHC colliders. Comparisons
with next-to-next-to-leading order results and with resummed ones are also
presented.Comment: Version accepted for publication by JHEP. One more figure added to
Sec 4.1.2 and two more explanatory figures and comments added to Sec 4.3 on
p_T distribution
A Positive-Weight Next-to-Leading-Order Monte Carlo for Heavy Flavour Hadroproduction
We present a next-to-leading order calculation of heavy flavour production in
hadronic collisions that can be interfaced to shower Monte Carlo programs. The
calculation is performed in the context of the POWHEG method. It is suitable
for the computation of charm, bottom and top hadroproduction. In the case of
top production, spin correlations in the decay products are taken into account.Comment: 18 pages, 12 figures. Few misprints corrected, references updated,
final remarks adde
Heavy Flavour Production
We review the status of heavy flavour production in QCD. Comparison of
experimental and theoretical results for top and bottom production are given.
Selected topics in charm production are also discussed.Comment: 18 pages, Latex, epsfig, 12 tar-gzip-uuencoded figures. Invited talk
given at the XV International conference "Physics in Collisions", Cracow,
Poland, June 8-10, 199
The p_T Spectrum in Heavy-Flavour Photoproduction
We consider the transverse-momentum distribution of heavy flavours in
photon-hadron collisions. We present a formalism in which large
transverse-momentum logarithms are resummed to the next-to-leading level, and
mass effects are included exactly up to order alpha_em alpha_s^2, so as to
retain predictivity at both small and large transverse momenta.
Phenomenological applications relevant to charm photoproduction at HERA are
given.Comment: 26 pages, Latex, epsfig, 15 figures. Submitted to JHE
The \pt spectrum of heavy quarks in photoproduction
We illustrate a formalism that allows to match the next-to-leading order
cross section for the photoproduction of heavy quarks to the cross section
obtained by resumming logarithms of \pt/m to the next-to-leading accuracy,
thus giving a sensible prediction for any value of \pt. We present a
comparison between our predictions and H1 and ZEUS data.Comment: 4 pages Latex; 3 figures included. Talk given at DIS01, 27 April - 1
May 2001, Bologna, Ital
Is There a Significant Excess in Bottom Hadroproduction at the Tevatron?
We discuss the excess in the hadroproduction of B mesons at the Tevatron. We
show that an accurate use of up-to-date information on the B fragmentation
function reduces the observed excess to an acceptable level. Possible
implications for experimental results reporting bottom quark cross sections,
also showing an excess with respect to next-to-leading order theoretical
predictions, are discussed.Comment: 5 pages, Latex, 4 figures. Submitted to Phys. Rev. Let
QCD in e+e- collisions at 2 TeV
We discuss some topics in QCD studies at 2 TeV. Particular emphasis is given
to the separation of pure QCD events from the WW and the t-tbar backgroundsComment: 10 pages, Latex, epsfig, 7 figures To appear in the Proceedings of
the 1995 "Workshop on Physics with e+e- Linear Colliders", Annecy-Gran
Sasso-DES
A Positive-Weight Next-to-Leading-Order Monte Carlo for e+e- Annihilation to Hadrons
We apply the positive-weight Monte Carlo method of Nason for simulating QCD
processes accurate to Next-To-Leading Order to the case of e+e- annihilation to
hadrons. The method entails the generation of the hardest gluon emission first
and then subsequently adding a `truncated' shower before the emission. We have
interfaced our result to the Herwig++ shower Monte Carlo program and obtained
better results than those obtained with Herwig++ at leading order with a matrix
element correction.Comment: 21 pages, 11 figures, 2 tables Reason for replacement: minor
corrections, typos and 1 changed referenc
The Resummation of Soft Gluon in Hadronic Collisions
We compute the effects of soft gluon resummation for the production of high
mass systems in hadronic collisions. We carefully analyse the growth of the
perturbative expansion coefficients of the resummation formula. We propose an
expression consistent with the known leading and next-to-leading resummation
results, in which the coefficients grow much less than factorially. We apply
our formula to Drell--Yan pair production, heavy flavour production, and the
production of high invariant mass jet pairs in hadronic collisions. We find
that, with our formula, resummation effects become important only fairly close
to the threshold region. In the case of heavy flavour production we find that
resummation effects are small in the experimental configurations of practical
interest.Comment: 45 pages, Latex, epsfig, 10 figures. Minor corrections to text,
notation and references. The previously quoted HERAb NLO bottom production
cross section was wrong, and it has been fixed. Accepted for Publication on
Nucl. Phys.
Matching matrix elements and shower evolution for top-quark production in hadronic collisions
We study the matching of multijet matrix elements and shower evolution in the
case of top production in hadronic collisions at the Tevatron and at the LHC.
We present the results of the matching algorithm implemented in the ALPGEN
Monte Carlo generator, and compare them with results obtained at the parton
level, and with the predictions of the MC@NLO approach. We highlight the
consistency of the matching algorithm when applied to these final states, and
the excellent agreement obtained with MC@NLO for most inclusive quantities. We
nevertheless identify also a remarkable difference in the rapidity spectrum of
the leading jet accompanying the top quark pair, and comment on the likely
origin of this discrepancy.Comment: 22 pages, 13 figures, 5 tables. JHEP styl
- …