共查询到20条相似文献,搜索用时 15 毫秒
1.
Standard SU(2) Heavy Baryon Chiral Perturbation Theory is extended in order to include the case of small or even vanishing quark condensate.
The effective lagrangian is given to in its most general form and to in the scalar sector. A method is developed to efficiently construct the relativistic baryonic effective lagrangian for chiral
SU(2) to all orders in the chiral expansion. As a first application, mass- and wave-function renormalization as well as the
scalar form factor of the nucleon is calculated to . The result is compared to a dispersive analysis of the nucleon scalar form factor adopted to the case of a small quark condensate.
In this latter analysis, the shift of the scalar form factor between the Cheng-Dashen point and zero momentum transfer is
found to be enhanced over the result assuming strong quark condensation by up to a factor of two, with substantial deviations
starting to be visible for .
Received: 22 July 1998 / Revised version: 2 September 1998 / Published online: 2 November 1998 相似文献
2.
M. Diehl A. Manashov A. Schäfer 《The European Physical Journal A - Hadrons and Nuclei》2007,31(3):335-355
We complete the analysis of twist-two generalized parton distributions of the nucleon in one-loop order of heavy-baryon chiral
perturbation theory. Extending our previous study of the chiral-even isosinglet sector, we give results for chiral-even isotriplet
distributions and for the chiral-odd sector. We also calculate the one-loop corrections for the chiral-odd generalized parton
distributions of the pion. 相似文献
3.
We present the first heavy-baryon chiral perturbation theory calculation at order Omicron(p(4)) for the spin-dependent amplitudes for virtual Compton scattering off the nucleon and extract the Omicron(p(4)) results for the generalized spin polarizabilities of the nucleon. 相似文献
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Ulf-G Meißner 《The European Physical Journal A - Hadrons and Nuclei》2003,18(2-3):487-490
I present and discuss recent results on elastic pion-nucleon scattering and near-threshold neutral-pion electroproduction off deuterium obtained in the framework of chiral perturbation theory.Received: 30 September 2002, Published online: 22 October 2003PACS:
13.75.Gx Pion-baryon interactions - 25.30.Rw Electroproduction reactions - 12.39.Fe Chiral Lagrangians 相似文献
6.
B. Borasoy 《The European Physical Journal C - Particles and Fields》1999,8(1):121-130
The -terms are calculated at next-to-leading order in heavy baryon chiral perturbation theory by employing a cutoff regularization.
The results do not depend on the cutoff value to the order we are working . The baryon masses and are used to perform a least-squares fit to the three appearing low-energy constants and predictions for the two KN
-terms and the strange contribution to the nucleon mass are made. The lack of convergence in the chiral expansions of these
quantities when regularized dimensionally is overcome in the cutoff scheme. The -term shifts to the pertinent Cheng-Dashen points are calculated. We also include the spin-3/2 decuplet in the effective theory.
Received: 21 July 1998 / Revised version: 31 August 1998 / Published online: 25 January 1999 相似文献
7.
We consider a symmetry-preserving approach to the nucleon-nucleon scattering problem in the framework of the higher-derivative formulation of baryon chiral perturbation theory. Within this framework the leading-order amplitude is calculated by solving renormalizable equations and corrections are taken into account perturbatively. 相似文献
8.
We analyze the amplitude for radiative charged pion photoproduction within the framework of heavy baryon chiral perturbation
theory and discuss the best experimental setup for the extraction of the pion polarizabilities from the differential cross
section.
Correspondence: C.-W. Kao, Department of Physics, Chung Yuan Christian University, Chung-Li 320, Taiwan 相似文献
9.
《Physics letters. [Part B]》1997,410(2-4):266-274
We establish exact relations between relativistic form factors and amplitudes for single-baryon processes and the corresponding quantities calculated in the framework of heavy baryon chiral perturbation theory. A crucial ingredient for the proper matching is the first complete treatment of baryon wave function renormalization in heavy baryon chiral perturbation theory. 相似文献
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We consider a new approach to the nucleon-nucleon scattering problem in the framework of the higher-derivative formulation of baryon chiral perturbation theory. Starting with a Lorentz-invariant form of the effective Lagrangian we work out a new symmetry-preserving framework where the leading-order amplitude is calculated by solving renormalizable equations and corrections are taken into account perturbatively. Analogously to the KSW approach, the (leading) renormalization scale dependence to any finite order is absorbed in the redefinition of a finite number of parameters of the effective potential at given order. On the other hand, analogously to Weinberg’s power counting, the one-pion-exchange potential is of leading order and is treated non-perturbatively. 相似文献
12.
D. Djukanovic J. Gegelia S. Scherer 《The European Physical Journal A - Hadrons and Nuclei》2006,29(3):337-342
Using the examples of pion-nucleon scattering and the nucleon mass we analyze the convergence of perturbative series in the
framework of baryon chiral perturbation theory. For both cases we sum up sets of an infinite number of diagrams by solving
equations exactly and compare the solutions with the perturbative contributions. 相似文献
13.
《Nuclear Physics A》1999,660(1):57-68
Generalized nucleon polarizabilities for virtual photons can be defined in terms of electroproduction cross sections as function of the 4-momentum transfer Q2. In particular, the sum of the generalized electric and magnetic polarizabilities Σ=α+β and the spin polarizability γ can be expressed by virtual photon absorption cross sections integrated over the excitation energy. These quantities have been calculated within the framework of the recently developed unitary isobar model for pion photo- and electroproduction on the proton, which describes the available experimental data up to an excitation energy of about 1 GeV. Our results have been compared to the predictions of chiral perturbation theory. 相似文献
14.
《Physics letters. [Part B]》1999,461(3):167-174
Considerable confusion in the literature about heavy baryon chiral perturbation theory, its convergence properties, and appropriate calculational techniques, make it timely to discuss the nonleptonic p-wave decays of the octet of baryons. We present model independent results. 相似文献
15.
《Nuclear Physics A》1999,646(3):343-363
We develop a method for constructing the heavy baryon chiral perturbation theory (HBChPT) Lagrangian, to a given chiral order, within HBChPT. We work within SU(2) theory, with only the pion field interacting with the nucleon. The main difficulties, which are solved, are to develop techniques for implementing charge conjugation invariance, and for taking the nucleon on shell, both within the non-relativistic formalism. We obtain complete lists of independent terms in LHBChPT through O(q3) for off-shell nucleons. Then, eliminating equation-of-motion (e.o.m.) terms at the relativistic and non-relativistic level (both within HBChPT), we obtain LHBChPT for on-shell nucleons, through O(q3). The extension of the method (to obtain on-shell LHBChPT within HBChPT) to higher orders is also discussed. 相似文献
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Li-Sheng Geng 《Frontiers of Physics》2013,8(3):328-348
Baryon chiral perturbation theory (BChPT), as an effective field theory of low-energy quantum chromodynamics (QCD), has played and is still playing an important role in our understanding of non-perturbative strong-interaction phenomena. In the past two decades, inspired by the rapid progress in lattice QCD simulations and the new experimental campaign to study the strangeness sector of low-energy QCD, many efforts have been made to develop a fully covariant BChPT and to test its validity in all scenarios. These new endeavours have not only deepened our understanding of some long-standing problems, such as the power-counting-breaking problem and the convergence problem, but also resulted in theoretical tools that can be confidently applied to make robust predictions. Particularly, the manifestly covariant BChPT supplemented with the extended-on-mass-shell (EOMS) renormalization scheme has been shown to satisfy all analyticity and symmetry constraints and converge relatively faster compared to its non-relativistic and infrared counterparts. In this article, we provide a brief review of the fully covariant BChPT and its latest applications in the u, d, and s three-flavor sector. 相似文献
20.
The generalized polarizabilities of the nucleon have been calculated in the one-loop approximation of the linear sigma model in the limit of infinite sigma mass. In particular, we have investigated the spin-independent amplitude of virtual Compton scattering off the nucleon. The dependence of the polarizabilities on the momentum transferQ has been compared with two recent model calculations. It has been shown in the linear sigma model that only two of the three scalar polarizabilities are independent quantities. Particular attention has been paid to the real photon point (Q 2=0), where the results of the relativisitc chiral perturbation theory have been recovered. 相似文献