108,461 research outputs found
Breaking Electroweak Symmetry Strongly
The problem of electroweak symmetry breaking is reviewed with discussion of
future relevant experimentation at LHC and linear colliders. The
possibility of strong electroweak symmetry breaking is examined in more detail,
using the BESS (Breaking Electroweak Symmetry Strongly) model as a basis for
the discussion. The formal constructions are briefly presented and the possible
expectations at future colliders are summarized.Comment: 20 pages, LaTeX, UGVA-DPT 1994/04-846. To appear in the Memorial
Volume for Professor Robert Marshak, edited by E.C.G. Sudarshan, World
Scientific Publishing Compan
Anti-transpirant effects on vine physiology, berry and wine composition of cv. Aglianico (Vitis vinifera L.) Grown in South Italy
In viticulture, global warming requires reconsideration of current production models. At the base of this need there are some emerging phenomena: modification of phenological phases; acceleration of the maturation process of grapes, with significant increases in the concentration of sugar musts; decoupling between technological grape maturity and phenolic maturity. The aim of our study was to evaluate the effect of a natural anti-transpirant on grapevine physiology, berry, and wine composition of Aglianico cultivar. For two years, Aglianico vines were treated at veraison with the anti-transpirant Vapor Gard and compared with a control sprayed with only water. A bunch thinning was also applied to both treatments. The effectiveness of Vapor Gard were assessed through measurements of net photosynthesis and transpiration and analyzing the vegetative, productive and qualitative parameters. The results demonstrate that the application of antitranspirant reduced assimilation and transpiration rate, stomatal conductance, berry sugar accumulation, and wine alcohol content. No significant differences between treatments were observed for other berry and wine compositional parameters. This method may be a useful tool to reduce berry sugar content and to produce wines with a lower alcohol content
Stochasticity effects in quantum radiation reaction
When an ultrarelativistic electron beam collides with a sufficiently intense
laser pulse, radiation-reaction effects can strongly alter the beam dynamics.
In the realm of classical electrodynamics, radiation reaction has a beneficial
effect on the electron beam as it tends to reduce its energy spread. Here, we
show that when quantum effects become important, radiation reaction induces the
opposite effect, i.e., the electron beam spreads out after interacting with the
laser pulse. We identify the physical origin of this opposite tendency in the
intrinsic stochasticity of photon emission, which becomes substantial in the
full quantum regime. Our numerical simulations indicated that the predicted
effects of the stochasticity can be measured already with presently available
lasers and electron accelerators.Comment: 5 pages, 2 figure
Complete treatment of single-photon emission in planar channeling
Approximate solutions of the Dirac equation are found for ultrarelativistic
particles moving in a periodic potential, which depends only on one coordinate,
transverse to the largest component of the momentum of the incoming particle.
As an example we employ these solutions to calculate the radiation emission of
positrons and electrons trapped in the planar potential found between the (110)
planes in Silicon. This allows us to compare with the semi-classical method of
Baier, Katkov and Strakhovenko, which includes the effect of spin and photon
recoil, but neglects the quantization of the transverse motion. For high-energy
electrons, the high-energy part of the angularly integrated photon energy
spectrum calculated with the found wave functions differs from the
corresponding one calculated with the semi-classical method. However, for lower
particle energies it is found that the angularly integrated emission energy
spectra obtained via the semi-classical method is in fairly good agreement with
the full quantum calculation except that the positions of the harmonic peaks in
photon energy and the photon emission angles are shifted
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