Search results for "RULE"
showing 10 items of 1403 documents
Test of the heavy quark-light diquark approximation for baryons with a heavy quark
2008
We check a commonly used approximation in which a baryon with a heavy quark is described as a heavy quark-light diquark system. The heavy quark influences the diquark internal motion reducing the average distance between the two light quarks. Besides, we show how the average distance between the heavy quark and any of the light quarks, and that between the heavy quark and the center of mass of the light diquark, are smaller than the distance between the two light quarks, which seems to contradict the heavy quark-light diquark picture. This latter result is in agreement with expectations from QCD sum rules and lattice QCD calculations. Our results also show that the diquark approximations pr…
B and B-s decay constants from QCD duality at three loops
2004
Using special linear combinations of finite energy sum rules which minimize the contribution of the unknown continuum spectral function, we compute the decay constants of the pseudoscalar mesons B and B_s. In the computation, we employ the recent three loop calculation of the pseudoscalar two-point function expanded in powers of the running bottom quark mass. The sum rules show remarkable stability over a wide range of the upper limit of the finite energy integration. We obtain the following results for the pseudoscalar decay constants: f_B=178 \pm 14 MeV and f_{B_s}=200 \pm 14 MeV. The results are somewhat lower than recent predictions based on Borel transform, lattice computations or HQET…
πB8B8andσB8B8couplings from a chiral quark potential model
2008
From an SU(2)$\ensuremath{\bigotimes}$SU(2) chiral quark potential model incorporating spontaneous chiral symmetry breaking the asymptotic $\ensuremath{\pi}$ and $\ensuremath{\sigma}$ exchange pieces of the $\mathit{NN}$ potential are generated. From them the $\ensuremath{\pi}\mathit{NN}$ and $\ensuremath{\sigma}\mathit{NN}$ coupling constants can be extracted. The generalization to SU(3)$\ensuremath{\bigotimes}$SU(3) allows for a determination of $\ensuremath{\pi}{B}_{8}{B}_{8}$ and $\ensuremath{\sigma}{B}_{8}{B}_{8}$ coupling constants according to exact SU(3) hadron symmetry. The implementation of the values of the couplings at ${Q}^{2}=0$ provided by QCD sum rules and/or phenomenology m…
Detailed quantum-chromodynamic predictions for high-pTprocesses
1978
High-${p}_{T}$ single-particle inclusive cross section calculations are presented for the CERN ISR and ISABELLE energy ranges, taking into account all lowest-order hard-scattering subprocesses required by quantum chromodynamics (QCD). The input quark and gluon distribution and fragmentation functions were determined from analyses of deep-inelastic lepton data and were subject to various theoretical constraints such as sum rules and SU(3) symmetry. We thoroughly discuss the effects of the individual contributions from fermionic and gluonic subprocesses, as well as those effects stemming from QCD scaling violations in parton distributions and/or fragmentation functions. In particular, the inc…
A QCD calculation of the pion-nucleon sigma-term
1988
We present the results of a QCD sum rule calculation of the pion-nucleon sigma-term. Depending on the uncertain value of the four quark condensate we obtain σ=10...40 MeV.
Light quark masses from scalar sum rules
2001
7 páginas, 2 figuras, 1 tabla.-- arXiv:hep-ph/0110194v2
ESTIMATION OF PRIVATE AND SOCIAL RATES OF RETURN TO INVESTMENTS IN EDUCATION IN LATVIA
2013
The main aim of the paper is to evaluate the rates of return to investments in education at individual and society level as well. The task of the paper is to provide detailed analysis and estimation of the variables which impact the private and social rates of return. It is based on Professor Angel de la Fuente methodology complemented by Mincer earnings function and non-parametric DEA (Data Envelopment Analysis) method to estimate world technological frontier and the technological gap. For this purpose the authors build the matrix with respective years of schooling depending from level of schooling and birth of year taking into account the differences in schooling system since 1940ties. Th…
A Dynamic Reasoning Architecture for Computer Network Management
2005
This paper focuses on improving network management and monitoring by the adoption of Artificial Intelli- gence techniques. In order to allow automated reasoning on networking concepts, we defined an accurate ontologi- cal model capable of describing as better as possible the networking domain. The thorough representation of the do- main knowledge is used by a Logical Reasoner, which is an expert system capable of performing high-level manage- ment tasks.
Energy-weighted M1 sum rule with explicit δ degrees of freedom
1985
Abstract The influence of Δ degrees of freedom on the energy-weighted M1 sum rule is investigated and applied to 2 H and 4 He. Using π- and ρ-exchange potentials a reduction of the potential contribution of the order of 50% is obtained. The absolute value of the sum rule is strongly dependent on the short-range behaviour of the nuclear wave function. Furthermore, the contribution of c.m. effects is evaluated and found to be of the order of 5–10%.
THE THEORIES AND PRACTICES OF LOPE AND MORATÍN: THE NEW THEATRE AND 'THE NEW PLAY'
2021
En este artículo, por primera vez, se ponen en relación las teorías teatrales de dos dramaturgos españoles que crearon escuela: Lope de Vega y Leandro Fernández de Moratín. Dos siglos separan sus creaciones, pero ambos pretendieron renovar la escena con sus poéticas, ambos pretendieron una «nueva comedia» que rompiera con las tradiciones teatrales inmediatamente anteriores. Las obras dramáticas de uno y otro autor, en realidad se sitúan en polos opuestos en cuanto a su extensión; la de Lope abarca más de cuatrocientos títulos, mientras que Moratín apenas tiene en su haber media decena de piezas. El más fecundo e internacional poeta dramático español y el más comedido de entre los dramaturgo…