1,164 research outputs found
PROSPINO: A Program for the Production of Supersymmetric Particles in Next-to-leading Order QCD
A Fortran-program for the production cross-sections of squarks and gluinos at
hadron colliders is described. It includes full next-to-leading order SUSY-QCD
corrections to all possible final states (\squark\squarkbar, \gluino\gluino,
\squark\gluino, \squark\squark). The program allows to calculate total
cross-sections as well as differential distributions in the transverse momentum
p_t and the rapidity y of one of the outgoing particles. In addition cuts in
p_t and y can easily be implemented.Comment: 12 pages, latex, no figures, Complete postscript file and FORTRAN
source codes available from http://wwwcn.cern.ch/~mspira/prospino
SUSY Particle Production at the Tevatron
The calculation of the next-to-leading order SUSY-QCD corrections to the
production of squarks, gluinos and gauginos at the Tevatron is reviewed. The
NLO corrections stabilize the theoretical predictions of the various production
cross sections significantly and lead to sizeable enhancements of the most
relevant cross sections for scales near the average mass of the produced
massive particles. We discuss the phenomenological consequences of the results
on present and future experimental analyses.Comment: 13 pages, latex, 9 figures, further extended versio
A Note on W Production at HERA
We discuss W boson production at HERA including NLO QCD corrections.Comment: 2 pages, latex, 2 figures, Contribution to the 3rd UK Phenomenology
Workshop on HERA Physics, Durham, 20-25 Sep. 199
Squark and Gluino Production at Hadron Colliders
We have determined the theoretical predictions for the cross-sections of
squark and gluino production at \ppb and colliders (Tevatron and LHC) in
next-to-leading order of supersymmetric QCD. By reducing the dependence on the
renormalization/factorization scale considerably, the theoretically predicted
values for the cross-sections are much more stable if these higher-order
corrections are implemented. If squarks and gluinos are discovered, this
improved stability translates into a reduced error on the masses, as extracted
experimentally from the size of the production cross-sections. The
cross-sections increase significantly if the next-to-leading order corrections
are included at a renormalization/factorization scale near the average mass of
the produced massive particles. This rise results in improved lower bounds on
squark and gluino masses. By contrast, the shape of the transverse-momentum and
rapidity distributions remains nearly unchanged when the next-to-leading order
corrections are included.Comment: 60 pages, Latex2e, 24 figures (uses epsfig.sty
Lepton flavour violating stau decays versus seesaw parameters: correlations and expected number of events for both seesaw type-I and II
In minimal supergravity (mSugra), the neutrino sector is related to the
slepton sector by means of the renormalization group equations. This opens a
door to indirectly test the neutrino sector via measurements at the LHC.
Concretely, for the simplest seesaw type-I, we present the correlations between
seesaw parameters and ratio of stau lepton flavour violating (LFV) branching
ratios. We find some simple, extreme scenarios for the unknown right-handed
parameters, where ratios of LFV rates correlate with neutrino oscillation
parameters. On the other hand, we scan the mSugra parameter space, for both
seesaw type-I and II, to find regions where LFV stau decays can be maximized,
while respecting low-energy experimental bounds. We estimate the expected
number of events at the LHC for a sample luminosity of L = 100 fb^{-1}.Comment: 10 pages, 6 figures, 1 table, to appear in the proceedings of
DISCRETE'08 Symposium on Prospects in the Physics of Discrete Symmetries,
11-16 December 2008, Valencia, Spain; some comments adde
QCD Corrections to SUSY Higgs Production: The Role of Squark Loops
We calculate the two-loop QCD corrections to the production of the neutral
supersymmetric Higgs bosons via the gluon fusion mechanism at hadron colliders,
including the contributions of squark loops. To a good approximation, these
additional contributions lead to the same QCD corrections as in the case where
only top and bottom quark loops are taken into account. The QCD corrections are
large and increase the Higgs production cross sections significantly.Comment: 5 pages, latex, 2 figure
Production of Charginos/Neutralinos and Sleptons at Hadron Colliders
We analyse the production of charginos/neutralinos and sleptons at the hadron colliders Tevatron and LHC in the direct channels: p\bar{p}/pp \to \tilde{\chi}_i \tilde{\chi}_j + X\tilde{\ell} \bar{\tilde{\ell}'} +X$. The cross sections for these reactions are given in next-to-leading order SUSY QCD. By including the higher-order corrections, the predictions become theoretically stable, being nearly independent of the factorization and renormalization scales. Since the corrections increase the cross sections, the discovery range for these particles is extended in the refined analysis
NLO QCD corrections to t anti-t H production in hadron collisions
The Higgs boson H of the Standard Model can be searched for in the channels p
pbar / pp -> t tbar H + X at the Tevatron and the LHC. The cross sections for
these processes and the final-state distributions of the Higgs boson and top
quarks are presented at next-to-leading order QCD. To calculate these QCD
corrections, a special calculational technique for pentagon diagrams has been
developed and the dipole subtraction formalism has been adopted for massive
particles. The impact of the corrections on the total cross sections is
characterized by K factors, the ratios of the cross sections in next-to-leading
order over leading order QCD. At the central scale mu_0 = (2 m_t + M_H)/2 the K
factors are found to be slightly below unity for the Tevatron (K \sim 0.8) and
slightly above unity for the LHC (K \sim 1.2). Including the corrections
significantly stabilizes the theoretical predictions for total cross sections
and for the distributions in rapidity and transverse momentum of the Higgs
boson and top quarks.Comment: 50 pages, LaTeX, 17 figure
Top quark associated production of topcolor pions at hadron colliders
We investigate the associated production of a neutral physical pion with top
quarks in the context of topcolor assisted technicolor. We find that single-top
associated production does not yield viable rates at either the Tevatron or
LHC. tt-associated production at the Tevatron is suppressed relative to
Standard Model ttH, but at the LHC is strongly enhanced and would allow for
easy observation of the main decay channels to bottom quarks, and possible
observation of the decay to gluons.Comment: 13 pages, 4 figures, submitted to PR
Neutral Higgs-Boson Pair Production at Hadron Colliders: QCD Corrections
Neutral Higgs-boson pair production provides the possibility of studying the
trilinear Higgs couplings at future high-energy colliders. We present the QCD
corrections to the gluon-initiated processes in the limit of a heavy top quark
in the loops and the Drell-Yan-like pair production of scalar and pseudoscalar
Higgs particles. The pp cross sections are discussed for LHC energies within
the Standard Model and its minimal supersymmetric extension. The QCD
corrections are large, enhancing the total cross sections significantly.Comment: 26 pages, latex, 9 ps figure
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