5,123 research outputs found
Using Two-jet Events to Understand Hadronization
While the hard phase of the strong interaction is well described by
perturbative QCD, the soft hadronization phase is less understood. Benefiting
from the high statistics from e+e- experiments at the Z0 resonance, it is
possible to impose strong two-jet cuts on the data without loosing the
statistical significance. In these events perturbative activity is suppressed
and hadronization effects can be more prominent. We show that after proper
event cuts a set of observables are sensitive to differences in the
hadronization models. These observables can thus be important tools for a more
detailed study of the hadronization mechanism.Comment: 18 pages, 6 ps figure
Effects of different closures for thickness diffusivity
The effects of spatial variations of the thickness diffusivity (K) appropriate to the parameterisation of [Gent, P.R. and McWilliams, J.C., 1990. Isopycnal mixing in ocean circulation models. J. Phys. Oceanogr., 20, 150–155.] are assessed in a coarse resolution global ocean general circulation model. Simulations using three closures yielding different lateral and/or vertical variations in K are compared with a simulation using a constant value. Although the effects of changing K are in general small and all simulations remain biased compared to observations, we find systematic local sensitivities of the simulated circulation on K. In particular, increasing K near the surface in the tropical ocean lifts the depth of the equatorial thermocline, the strength of the Antarctic Circumpolar Current decreases while the subpolar and subtropical gyre transports in the North Atlantic increase by increasing K locally. We also find that the lateral and vertical structure of K given by a recently proposed closure reduces the negative temperature biases in the western North Atlantic by adjusting the pathways of the Gulf Stream and the North Atlantic Current to a more realistic position
Lasing characteristics of gas mixtures involving UFG: Application to nuclear pumping of lasers
Intense blue-green fluorescence from a structured band centered at lambda approximately 484 nm was observed from Ar, CF3I and NF3 gas mixtures excited by an electron beam. This emission was tentatively assigned to the E yields A transition of the iodine monofluoride (IF) molecule. The fluorescence efficiency of the IF(E yields A) band and the IF (E) state radiative lifetime were estimated to be approximately 6% and 15 ns, respectively. The emission band structure, the short IF(E) radiative lifetime and the Franck-Condon shift between the E and A states suggest that IF is an attractive candidate for a blue-green laser
Four-point correlators of BPS operators in N=4 SYM at order g^4
We study the large N degeneracy in the structure of the four-point amplitudes
of 1/2-BPS operators of arbitrary weight k in perturbative N=4 SYM theory. At
one loop (order g^2) this degeneracy manifests itself in a smaller number of
independent conformal invariant functions describing the amplitude, compared to
AdS_5 supergravity results. To study this phenomenon at the two-loop level
(order g^4) we consider a particular N=2 hypermultiplet projection of the
general N=4 amplitude. Using the formalism of N=2 harmonic superspace we then
explicitly compute this four-point correlator at two loops and identify the
corresponding conformal invariant functions. In the cases of 1/2-BPS operators
of weight k=3 and k=4 the one-loop large N degeneracy is lifted by the two-loop
corrections. However, for weight k > 4 the degeneracy is still there at the
two-loop level. This behavior suggests that for a given weight k the degeneracy
will be removed if perturbative corrections of sufficiently high order are
taken into account. These results are in accord with the AdS/CFT duality
conjecture.Comment: 45 pages, latex, 14 figure
The Impact of Fiscal Restraint on Budgetary Allocations for Women's Programs
How did the fiscal restraints exercised during the time of fiscal difficulties in 1997-2003 affect the gender/women-targeted programs of the Philippine government? What does a close scrutiny of the government budget reveal regarding the implicit gender implications of such restraints? Manasan and Villanueva disclose some of their findings.budget analysis, gender analysis, women's programs
Looking Closely on Who Benefits from Public Subsidies in Health Care: a Gender Perspective
Do men benefit more than women from government expenditures in health care? Or do women have the upper hand? Using a sex-differentiated incidence analysis of the various Department of Health program expenditures, this Notes' authors assess who indeed benefits from such expenditures in terms of gender. And why.gender, benefit incidence analysis, gender analysis, public spending in health, sex-differentiated incidence analysis
Exceptional non-renormalization properties and OPE analysis of chiral four-point functions in N=4 SYM_4
We show that certain classes of apparently unprotected operators in N=4 SYM_4
do not receive quantum corrections as a consequence of a partial
non-renormalization theorem for the 4-point function of chiral primary
operators. We develop techniques yielding the asymptotic expansion of the
4-point function of CPOs up to order O(\lambda^2) and we perform a detailed OPE
analysis. Our results reveal the existence of new non-renormalized operators of
approximate dimension 6.Comment: an error in Sect. 4 corrected; references adde
Local integrands for the five-point amplitude in planar N=4 SYM up to five loops
Integrands for colour ordered scattering amplitudes in planar N=4 SYM are
dual to those of correlation functions of the energy-momentum multiplet of the
theory. The construction can relate amplitudes with different numbers of legs.
By graph theory methods the integrand of the four-point function of
energy-momentum multiplets has been constructed up to six loops in previous
work. In this article we extend this analysis to seven loops and use it to
construct the full integrand of the five-point amplitude up to five loops, and
in the parity even sector to six loops.
All results, both parity even and parity odd, are obtained in a concise local
form in dual momentum space and can be displayed efficiently through graphs. We
have verified agreement with other local formulae both in terms of
supertwistors and scalar momentum integrals as well as BCJ forms where those
exist in the literature, i.e. up to three loops.
Finally we note that the four-point correlation function can be extracted
directly from the four-point amplitude and so this uncovers a direct link from
four- to five-point amplitudes.Comment: 29 pages LaTeX, 8 figure
Exploring the S-Matrix of Massless Particles
We use the recently proposed generalised on-shell representation for
scattering amplitudes and a consistency test to explore the space of tree-level
consistent couplings in four-dimensional Minkowski spacetime. The extension of
the constructible notion implied by the generalised on-shell representation,
i.e. the possibility to reconstruct at tree level all the scattering amplitudes
from the three-particle ones, together with the imposition of the consistency
conditions at four-particle level, allow to rediscover all the known theories
and their algebra structure, if any. Interestingly, this analysis seems to
leave room for high-spin couplings, provided that at least the requirement of
locality is weakened. We do not claim to have found tree-level consistent
high-spin theories, but rather that our methods show signatures of them and
very likely, with a suitable modification, they can be a good framework to
perform a systematic search.Comment: 44 pages, 1 figur
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