13,829 research outputs found
Introduction to supergeometry
These notes are based on a series of lectures given by the first author at
the school of `Poisson 2010', held at IMPA, Rio de Janeiro. They contain an
exposition of the theory of super- and graded manifolds, cohomological vector
fields, graded symplectic structures, reduction and the AKSZ-formalism.Comment: Lecture notes of a course held at the school Poisson 2010 at IMPA,
July 2010; 21 pages; references improve
Resurrection of the genus Staphisagria J. Hill, sister to all the other Delphinieae (Ranunculaceae)
Molecular sequence data show that the three species of Delphinium subg. Staphisagria (J. Hill) Peterm. form the sister clade to Aconitum L., Aconitella Spach, Consolida (DC.) S.F. Gray, and all remaining species of Delphinium L. To account for this finding we resurrect Staphisagria J. Hill (1756). Names in Staphisagria are available for two of the species. We here make the required new combination for the third species, Staphisagria picta (Willd.) F. Jabbour, provide a key to the species, and illustrate one of them
On Kaon production in e+e- and Semi-inclusive DIS reactions
We consider semi-inclusive unpolarized DIS for the production of charged
kaons and the different possibilities to test the conventionally used
assumptions s-\bar=0 and D_d^{K^+-K^-}=0. The considered tests have the
advantage that they do not require any knowledge of the fragmentation
functions. We also show that measurements of both charged and neutral kaons
would allow the determination of the kaon FFs D_q^{K^++K^-} solely from SIDIS
measurements, and discuss the comparison of (D_u-D_d)^{K^+-K^-} obtained
independently in SIDIS and e+e- reactions. All analysis are performed in LO and
NLO in QCD. The feasibility of the tests to HERMES SIDIS data is considered.Comment: 7 pages, NLO analysis for all presented tests and feasibility to
HERMES data adde
Sea quark polarization and semi-inclusive DIS data
We investigate the potential impact of forthcoming Jefferson Lab
semi-inclusive polarized deep inelastic scattering proton measurements in the
determination of the sea quark polarization in the nucleon by means of a next
to leading order global QCD analysis. Specifically, we estimate the resulting
improvement in the constraints on polarized parton densities for the different
flavors, which is found to be significant for up and strange quarks, and the
correlation between remaining uncertainty ranges for each of the parton
species.Comment: 7 pages, 4 figures. Version to be published in the European Physical
Journal
Universality of non-leading logarithmic contributions in transverse-momentum distributions
We consider the resummation of the logarithmic contributions to the region of
small transverse momenta in the distributions of high-mass systems (lepton
pairs, vector bosons, Higgs particles, ....) produced in hadron collisions. We
point out that the resummation formulae that are usually used to compute the
distributions in perturbative QCD involve process-dependent form factors and
coefficient functions. We present a new universal form of the resummed
distribution, in which the dependence on the process is embodied in a single
perturbative factor. The new form simplifies the calculation of non-leading
logarithms at higher perturbative orders. It can also be useful to
systematically implement process-independent non-perturbative effects in
transverse-momentum distributions. We also comment on the dependence of these
distributions on the factorization and renormalization scales.Comment: misprints corrected in Eqs. (6), (7) and (12), results unchange
Direct Higgs production and jet veto at hadron colliders
We consider Higgs boson production through gluon--gluon fusion in hadron
collisions, when a veto is applied on the transverse momenta of the
accompanying hard jets. We compute the QCD corrections to this process at NLO
and NNLO, and present numerical results at the Tevatron and the LHC.Comment: 5 pages, 4 ps figures, presented at the XXXVIIth Rencontres de
Moriond, QCD and Hadronic interactions, Les Arc1800, Franc
Higgs production in hadron collisions: soft and virtual QCD corrections at NNLO
We consider QCD corrections to Higgs boson production through gluon-gluon
fusion in hadron collisions. Using the recently evaluated two-loop amplitude
for this process and the corresponding factorization formulae for soft-gluon
bremsstrahlung at O(alpha_s^2), we compute the soft and virtual contributions
to the NNLO cross section. We also discuss soft-gluon resummation at
next-to-next-to-leading logarithmic accuracy. Numerical results for Higgs boson
production at the LHC are presented.Comment: 17 pages, 4 figures included. One note and one reference adde
Higgs production at hadron colliders in (almost) NNLO QCD
We compute the soft and virtual NNLO QCD corrections to Higgs production
through gluon-gluon fusion at hadron colliders. We present numerical results
obtained at the LHC and at the Tevatron Run II.Comment: latex, 5 pages, presented at the XXXVIth Rencontres de Moriond, QCD
and Hadronic interactions, Les Arc1800, France and at the 9th International
Workshop on Deep Inelastic Scattering DIS2001, Bologna, Ital
Graph Saturation in Multipartite Graphs
Let be a fixed graph and let be a family of graphs. A
subgraph of is -saturated if no member of
is a subgraph of , but for any edge in , some element of
is a subgraph of . We let and
denote the maximum and minimum size of an
-saturated subgraph of , respectively. If no element of
is a subgraph of , then .
In this paper, for and we determine
, where is the complete balanced -partite
graph with partite sets of size . We also give several families of
constructions of -saturated subgraphs of for . Our results
and constructions provide an informative contrast to recent results on the
edge-density version of from [A. Bondy, J. Shen, S.
Thomass\'e, and C. Thomassen, Density conditions for triangles in multipartite
graphs, Combinatorica 26 (2006), 121--131] and [F. Pfender, Complete subgraphs
in multipartite graphs, Combinatorica 32 (2012), no. 4, 483--495].Comment: 16 pages, 4 figure
Quantum nondemolition measurement of mechanical motion quanta
The fields of opto- and electromechanics have facilitated numerous advances
in the areas of precision measurement and sensing, ultimately driving the
studies of mechanical systems into the quantum regime. To date, however, the
quantization of the mechanical motion and the associated quantum jumps between
phonon states remains elusive. For optomechanical systems, the coupling to the
environment was shown to preclude the detection of the mechanical mode
occupation, unless strong single photon optomechanical coupling is achieved.
Here, we propose and analyse an electromechanical setup, which allows to
overcome this limitation and resolve the energy levels of a mechanical
oscillator. We find that the heating of the membrane, caused by the interaction
with the environment and unwanted couplings, can be suppressed for carefully
designed electromechanical systems. The results suggest that phonon number
measurement is within reach for modern electromechanical setups.Comment: 8 pages, 5 figures plus 24 pages, 11 figures supplemental materia
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