1,991 research outputs found
WW scattering at the CERN LHC
A detailed study is presented of elastic WW scattering in the scenario that there are no new particles discovered prior to the commissioning of the CERN LHC. We work within the framework of the electroweak chiral Lagrangian and two different unitarization protocols are investigated. Signals and backgrounds are simulated to the final-state-particle level. A new technique for identifying the hadronically decaying W is developed, which is more generally applicable to massive particles which decay to jets where the separation of the jets is small. The effect of different assumptions about the underlying event is also studied. We conclude that the channel WW-->jj+lν may contain scalar and/or vector resonances which could be measurable after 100 fb-1 of LHC data
Partial Degree Formulae for Plane Offset Curves
In this paper we present several formulae for computing the partial degrees
of the defining polynomial of the offset curve to an irreducible affine plane
curve given implicitly, and we see how these formulae particularize to the case
of rational curves. In addition, we present a formula for computing the degree
w.r.t the distance variable.Comment: 24 pages, no figure
Conchoidal transform of two plane curves
The conchoid of a plane curve is constructed using a fixed circle in
the affine plane. We generalize the classical definition so that we obtain a
conchoid from any pair of curves and in the projective plane. We
present two definitions, one purely algebraic through resultants and a more
geometric one using an incidence correspondence in \PP^2 \times \PP^2. We
prove, among other things, that the conchoid of a generic curve of fixed degree
is irreducible, we determine its singularities and give a formula for its
degree and genus. In the final section we return to the classical case: for any
given curve we give a criterion for its conchoid to be irreducible and we
give a procedure to determine when a curve is the conchoid of another.Comment: 18 pages Revised version: slight title change, improved exposition,
fixed proof of Theorem 5.3 Accepted for publication in Appl. Algebra Eng.,
Commun. Comput
Diffractive Dijet Production
We explore the diffractive interaction of a proton with an anti-proton which
results in centrally produced dijets. This process has been recently studied at
the Tevatron. We make predictions within an Ingelman-Schlein approach and
compare them to the recent data presented by the CDF collaboration. Earlier
calculations resulted in theoretical cross-sections which are much larger than
those observed by CDF. We find that, after consideration of hadronisation
effects and the parton shower, and using parton density functions extracted
from diffractive deep inelastic scattering at HERA, it is possible to explain
the CDF data. We need to assume a gap survival probability of around 10% and
this is in good agreement with the value predicted by theory. We also find that
the non-diffractive contribution to the process is probably significant in the
kinematical region probed by the Tevatron.Comment: 12 pages, 6 figures, 3 table
Encoding points on hyperelliptic curves over finite fields in deterministic polynomial time
We present families of (hyper)elliptic curve which admit an efficient
deterministic encoding function
Application of density functional theory in the synthesis of electroactive polymers
A wide range of conjugated organic compounds undergo anodic electropolymerisation to produce polymers of high conductivity. However, electrooxidation does not always result in the formation of electroactive materials, since some reactions produce insulating films or soluble oligomers. Density functional theory (DFT) has been used to predict the outcome of electropolymerisation reactions by calculating the unpaired electron π-spin density distribution of monomeric radical cations, in order to determine coupling positions in the resultant polymers. π-Spin densities calculated for pyrrole, thiophene and (E)-stilbene are found to be in good agreement with experimental values. DFT has been used to investigate the low conductivity and redox inactivity of poly[(E)-3-styrylthiophenes] and poly[(E)-2-styrylheterocycles]. High positive spin densities at the alkene spacer linkage in the corresponding monomeric radical cations were found, suggesting crosslinking of the polymers via the double bond. In contrast, electroactive polymers of improved conductivity are formed from the electropolymerisation of some (Z)-2-α,β-diarylacrylonitriles. For these monomers, DFT calculations show the positions of highest spin density to be located at the α-positions of the heterocyclic rings, suggesting the presence of α,α′-linked monomeric couplings necessary for electroactivity
Double Diffraction Dissociation at High t
Diffractive scattering in the presence of a large momentum transfer is an
ideal place to study the short distance rapidity gap producing mechanism.
Previous studies (experimental and theoretical) in this area have focussed on
gaps between jets and on high- vector meson production. We propose the
measurement of double dissociation at high-. We examine the numerous
advantages to studying this more inclusive process and conclude that it is an
ideal place to study short distance diffraction.Comment: 12 pages, 8 figure
Diffractive upsilon production at the LHC
We compute the rate for diffractive upsilon meson production at the Tevatron
and the LHC. The upsilon is produced diffractively via the subprocess gamma + p
-> upsilon + p where the initial photon is radiated off an incoming proton (or
antiproton). We consider the possibility to use low angle proton detectors to
make a measurement of the gamma p cross-section and conclude that a measurement
of the cross-section at a centre of mass energy in excess of 1 TeV is possible
at the LHC. This is in the region where saturation effects are likely to reveal
themselves.Comment: 14 page
Cryptic photosynthesis, Extrasolar planetary oxygen without a surface biological signature
On the Earth, photosynthetic organisms are responsible for the production of
virtually all of the oxygen in the atmosphere. On the land, vegetation reflects
in the visible, leading to a red edge that developed about 450 Myr ago and has
been proposed as a biosignature for life on extrasolar planets. However, in
many regions of the Earth, and particularly where surface conditions are
extreme, for example in hot and cold deserts, photosynthetic organisms can be
driven into and under substrates where light is still sufficient for
photosynthesis. These communities exhibit no detectable surface spectral
signature to indicate life. The same is true of the assemblages of
photosynthetic organisms at more than a few metres depth in water bodies. These
communities are widespread and dominate local photosynthetic productivity. We
review known cryptic photosynthetic communities and their productivity. We link
geomicrobiology with observational astronomy by calculating the disk-averaged
spectra of cryptic habitats and identifying detectable features on an exoplanet
dominated by such a biota. The hypothetical cryptic photosynthesis worlds
discussed here are Earth-analogs that show detectable atmospheric biomarkers
like our own planet, but do not exhibit a discernable biological surface
feature in the disc-averaged spectrum.Comment: 23 pages, 2 figures, Astrobiology (TBP) - updated Table 1, typo in
detectable O2 correcte
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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