168 research outputs found
New results in the deformed N=4 SYM theory
We investigate various perturbative properties of the deformed N=4 SYM
theory. We carry out a three-loops calculation of the chiral matter superfield
propagator and derive the condition on the couplings for maintaining finiteness
at this order. We compute the 2-, 3- and 4-point functions of composite
operators of dimension 2 at two loops. We identify all the scalar operators
(chiral and non-chiral) of bare dimension 4 with vanishing one-loop anomalous
dimension. We compute some 2- and 3-point functions of these operators at two
loops and argue that the observed finite corrections cannot be absorbed by a
finite renormalization of the operators.Comment: LaTeX, 16 pages, 1 figure; references added; typos corrected; final
version to appear in Nucl. Phys.
Exact results in planar N=1 superconformal Yang-Mills theory
In the \beta-deformed N=4 supersymmetric SU(N) Yang-Mills theory we study the
class of operators O_J = Tr(\Phi_i^J \Phi_k), i\neq k and compute their exact
anomalous dimensions for N,J\to\infty. This leads to a prediction for the
masses of the corresponding states in the dual string theory sector. We test
the exact formula perturbatively up to two loops. The consistency of the
perturbative calculation with the exact result indicates that in the planar
limit the one--loop condition g^2=h\bar{h} for superconformal invariance is
indeed sufficient to insure the {\em exact} superconformal invariance of the
theory. We present a direct proof of this point in perturbation theory. The O_J
sector of this theory shares many similarities with the BMN sector of the N=4
theory in the large R--charge limit.Comment: LaTex, 14 pages, 3 figures; v2: minor corrections and one reference
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Is weak temperature dependence of electron dephasing possible?
The first-principle theory of electron dephasing by disorder-induced two
state fluctuators is developed. There exist two mechanisms of dephasing. First,
dephasing occurs due to direct transitions between the defect levels caused by
inelastic electron-defect scattering. The second mechanism is due to violation
of the time reversal symmetry caused by time-dependent fluctuations of the
scattering potential. These fluctuations originate from an interaction between
the dynamic defects and conduction electrons forming a thermal bath. The first
contribution to the dephasing rate saturates as temperature decreases. The
second contribution does not saturate, although its temperature dependence is
rather weak, . The quantitative estimates based on the
experimental data show that these mechanisms considered can explain the weak
temperature dependence of the dephasing rate in some temperature interval.
However, below some temperature dependent on the model of dynamic defects the
dephasing rate tends rapidly to zero. The relation to earlier studies of the
dephasing caused by the dynamical defects is discussed.Comment: 14 pages, 6 figures, submitted to PR
Rotating Strings with Two Unequal Spins in Lunin-Maldacena Background
We study a string motion in the Lunin-Maldacena background, that is, the
\beta-deformed AdS_5 \times \tilde{S}^5 background dual to a \beta-deformation
of \mathcal{N} = 4 super Yang-Mills theory. For real \beta we construct a
rotating and wound string solution which has two unequal spins in \tilde{S}^5.
The string energy is expressed in terms of the spins, the winding numbers and
the deformation parameter. In the expansion of \lambda/J^2 with the total spin
J and the string tension \sqrt{\lambda} we present ``one-loop" and ``two-loop"
energy corrections. The ``one-loop" one agrees with the one-loop anomalous
dimension of the corresponding gauge-theory scalar operators obtained in
hep-th/0503192 from the \beta-deformed Bethe equation as well as the
anisotropic Landau-Lifshitz equation.Comment: 13 pages, LaTeX, no figure
Wound-healing evaluation of ointment from Stryphnodendron adstringens (barbatimão) in rat skin
Temporal variability of soil water content under different surface conditions in the semiarid region of the Pernambuco state
Evidence for a mixed mass composition at the `ankle' in the cosmic-ray spectrum
We report a first measurement for ultra-high energy cosmic rays of the
correlation between the depth of shower maximum and the signal in the water
Cherenkov stations of air-showers registered simultaneously by the fluorescence
and the surface detectors of the Pierre Auger Observatory. Such a correlation
measurement is a unique feature of a hybrid air-shower observatory with
sensitivity to both the electromagnetic and muonic components. It allows an
accurate determination of the spread of primary masses in the cosmic-ray flux.
Up till now, constraints on the spread of primary masses have been dominated by
systematic uncertainties. The present correlation measurement is not affected
by systematics in the measurement of the depth of shower maximum or the signal
in the water Cherenkov stations. The analysis relies on general characteristics
of air showers and is thus robust also with respect to uncertainties in
hadronic event generators. The observed correlation in the energy range around
the `ankle' at differs significantly from
expectations for pure primary cosmic-ray compositions. A light composition made
up of proton and helium only is equally inconsistent with observations. The
data are explained well by a mixed composition including nuclei with mass . Scenarios such as the proton dip model, with almost pure compositions, are
thus disfavoured as the sole explanation of the ultrahigh-energy cosmic-ray
flux at Earth.Comment: Published version. Added journal reference and DOI. Added Report
Numbe
Influence of diameter measuring height on the adjustment of volume and biomass equations of cerrado in minas gerais
Anastrepha aczeli Blanchard and Anastrepha similis Greene (Diptera: Tephritidae) in Minas Gerais, Brazil
Pressão de preconsolidação e intervalo hídrico ótimo como indicadores de alterações estruturais de um latossolo e de um cambissolo sob cana-de-açúcar
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