2,945 research outputs found
Two-loop planar master integrals for the production of off-shell vector bosons in hadron collisions
We describe the calculation of all planar master integrals that are needed
for the computation of NNLO QCD corrections to the production of two off-shell
vector bosons in hadron collisions. The most complicated representatives of
integrals in this class are the two-loop four-point functions where two
external lines are on the light-cone and two other external lines have
different invariant masses. We compute these and other relevant integrals
analytically using differential equations in external kinematic variables and
express our results in terms of Goncharov polylogarithms. The case of two equal
off-shellnesses, recently considered in Ref. [1], appears as a particular case
of our general solution.Comment: 28 pages, many figures; ancillary files included with arXiv
submissio
Polypyrrole Coated PET Fabrics for Thermal Applications
Polypyrrole can be chemically synthesized on PET fabrics, giving rise to textiles with high electric conductivity. These textiles are suitable for several applications from antistatic films to electromagnetic interference shielding devices. Here we discuss the thermal-electric performance and the heat generation of polypyrrole coated PET fabric samples, previously studied because of their electric conductivity and electromagnetic interference shielding effectiveness. The measured Seebeck effect is comparable with that of metallic thermocouples. Since polypyrrole shows extremely low thermal diffusivities regardless of the electrical conductivity, the low thermal conductivity gives significant advantage to the thermoelectric figure-of-merit ZT, comparable with that of some traditional inorganic thermoelectric materials. The heat generation is also investigated for possible heating textile devices. The results confirm polypyrrole as a prom- ising material for thermal electric applications due to its easy preparation in low cost processin
Evaluating single-scale and/or non-planar diagrams by differential equations
We apply a recently suggested new strategy to solve differential equations
for Feynman integrals. We develop this method further by analyzing asymptotic
expansions of the integrals. We argue that this allows the systematic
application of the differential equations to single-scale Feynman integrals.
Moreover, the information about singular limits significantly simplifies
finding boundary constants for the differential equations. To illustrate these
points we consider two families of three-loop integrals. The first are
form-factor integrals with two external legs on the light cone. We introduce
one more scale by taking one more leg off-shell, . We analytically
solve the differential equations for the master integrals in a Laurent
expansion in dimensional regularization with . Then we show
how to obtain analytic results for the corresponding one-scale integrals in an
algebraic way. An essential ingredient of our method is to match solutions of
the differential equations in the limit of small to our results at
and to identify various terms in these solutions according to
expansion by regions. The second family consists of four-point non-planar
integrals with all four legs on the light cone. We evaluate, by differential
equations, all the master integrals for the so-called graph consisting of
four external vertices which are connected with each other by six lines. We
show how the boundary constants can be fixed with the help of the knowledge of
the singular limits. We present results in terms of harmonic polylogarithms for
the corresponding seven master integrals with six propagators in a Laurent
expansion in up to weight six.Comment: 27 pages, 2 figure
Dopamine: A Marker of Psychosis and Final Common Driver of Schizophrenia Psychosis
Our attempt to understand schizophrenia in neurochemical terms began with the landmark studies of Carlsson and Lindqvist (1) in the 1960s. The results of these studies, based on the action of chlorpromazine, were strengthened by the binding studies carried out in both Seeman's (2) and Synder's (3) laboratories, which showed that antipsychotic potency was correlated with dopamine D2 receptor binding. The one major exception to this correlation is clozapine, which appears to be the most effective available drug for treating schizophrenia symptoms. The most recent version of the resulting dopamine hypothesis suggests that genetic, environmental, and developmental variables play major etiological roles in schizophrenia, but that striatal dopamine presynaptic overactivity remains the final trigger resulting in psychosis.....
A planar four-loop form factor and cusp anomalous dimension in QCD
We compute the fermionic contribution to the photon-quark form factor to
four-loop order in QCD in the planar limit in analytic form. From the divergent
part of the latter the cusp and collinear anomalous dimensions are extracted.
Results are also presented for the finite contribution. We briefly describe our
method to compute all planar master integrals at four-loop order.Comment: 19 pages, 3 figures, v2: typo in (2.3) fixed and coefficients in
(2.6) corrected; references added and correcte
Optimizing Max Camber Points Along Thin Triangular Airfoils for Higher Lift/Drag Ratios
The purpose of this report is to expand knowledge on the lift and drag properties of thin triangular airfoils, and determine whether or not they are a viable option for low-Reynolds number applications. Thin triangular airfoils were thought to be more efficient than standard NACA airfoils under specific conditions. This experiment was performed through the wind tunnel testing of a NACA 2412 and nine thin triangular airfoils with varying max camber points. Between the Reynolds numbers of 30-42,000, lift and drag values were collected at varying angles of attack. Overall, it was found that the thin triangular airfoils proved to have unique lift and drag characteristics when compared to the standard NACA 2412
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