Meson Clouds and Dressed Constituent Quarks in the Complete Rg-Improvement Approach

Keshavarzian, K.; Mirjalili, A.; Yazdanpanah, M. M.

doi:10.1142/s0217751x08042900

Cited by 10 publications

(13 citation statements)

References 39 publications

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“…Mellin transformation from Eq. (36), will yield the moment distributions for valons [14]. The moments of quark and gluon distributions at any energy scale inside the meson are obtained by multiplying the valon moments with the appropriate moments of singlet, non-singlet and gluon sectors.…”

Section: Valon Modelmentioning

confidence: 99%

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LowQ²proton structure function, using gluon and pseudoscalar meson clouds in the constituent quark framework

Mirjalili

Yazdanpanah

Taghavi-Shahri

et al. 2010

J. Phys. G: Nucl. Part. Phys.

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Abstract. The idea of the meson cloud approach in the chiral quark model has been extended to include gluon cloud in order to achieve the parton densities in the nucleon, based on the constitute quark framework. The splitting function of the quark to the quark-meson and quark-gluon at low Q 2 value are used to obtain parton densities in the constituent quark. The phenomenological constituent model is employed to extract the parton distributions in the proton at low Q 2 value. Since we have access to the parton densities at low Q 2 , we are able to obtain F 2 (x, Q 2 ) structure function at low Q 2 value. The result is in good agreement with available experimental data and some theoretical models. To confirm the validity of our calculations, the fraction of total momentum of proton which is carried by gluon at high Q 2 and also the Gottfried sum rule are computed. The results are in good agreement with what are expected.

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Section: Valon Modelmentioning

confidence: 99%

“…As should be noticed, the main ingredients of this paper are two subjects. In continuation of our previous work [14] we add the gluon cloud to the χQM while we use an effective lagrangian at low Q 2 values. We resort to a constituent quark model to extract parton densities inside the proton.…”

Section: Introductionmentioning

confidence: 99%

LowQ²proton structure function, using gluon and pseudoscalar meson clouds in the constituent quark framework

Mirjalili

Yazdanpanah

Taghavi-Shahri

et al. 2010

J. Phys. G: Nucl. Part. Phys.

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“…The left hand side of Eq. (50) can be calculated, based on the Valon framework [15], while its right hand side comes from χQM [17,22]. As a result we consider an additional coefficient to fill this gap between the two models and write E u = E d = E s = N .…”

Section: Non-degenerate Statementioning

confidence: 99%

“…In our calculations below we choose the former value. The cut-off parameter is Λ and is usually determined phenomenologically [1,2,20,22]. We use its previously determined value, Λ = 1.4 GeV [2].…”

Section: Unpolarized Chiral Quark Modelmentioning

confidence: 99%

Meson polarized distribution function and mass dependence of the nucleon parton densities

Mirjalili¹,

Keshavarzian²

2014

Chinese Phys. C

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The polarized distribution functions of mesons, including pion, kaon and eta, using the proton structure function, are calculated. We are looking for a relationship between the polarized distribution of mesons and the polarized structure of nucleons. We show that the meson polarized parton distributions leads to zero total spin for mesons, considering the orbital angular momentum of quarks and gluons inside the meson. Two separate Monte Carlo algorithms are applied to compute the polarized parton distributions of the kaon. Via the mass dependence of quark distributions, the distribution function of the eta meson is obtained. A new method by which the polarized sea quark distributions of protons are evolved separately -which cannot be performed easily using the standard solution of DGLAP equations -is introduced. The mass dependence of these distributions is obtained, using the renormalization group equation which makes their evolutions more precise. Comparison between the evolved distributions and the available experimental data validates the suggested solutions for separate evolutions.In Part 1, we calculate the bare quark distributions using the proton polarized structure function g p 1 (x), using data from [10]. Then we compute the ratio of the polarized valence data of kaons to that of pions, δq K val /δq π val , using the data for their unpolarized ratio, q K val /q π val [11], based on two separate Monte Carlo algorithms. We also calculate the polarized valence ratio of eta mesons to pions, δq η val /δq π val , using the mass dependence of the valence quark distribution inside the meson. Substituting these ratios into the chiral quark model (χQM) equations and fitting with experimental data (or any reasonable phenomenological model), the polarized distribution functions in pion, kaon and eta mesons at low energy scales will be obtained. Following that, the evolution of the PDFs, employing the DGLAP equations, can be done straightforwardly [12][13][14][15]. Using these evolved PDFs, we can extract the values of the orbital angular momentum of quarks and gluons inside mesons [6].In Part 2, the PPDFs of the proton, using the distributions extracted for mesons, are calculated. The valence PPDF of the proton can be evolved easily using the non-singlet moment δM NS . Since the DGLAP equations can thoroughly evolve only the sea quark distribution, however, the evolution of the separated sea quarks is more complicated. There are reasonable methods to separate the evolution of sea quarks [16] but in this work we use the running mass and renormalization equation to make the sea quark distribution functions depend on the quark masses. Thereby, the eigenvalues of the evolution operator become non-degenerate. The sea quark distributions at low scale Q 2 0 , arising from χQM , are unsymmetrized. The different eigenvalues of the evolution operator, which are obtained as a result of the new method introduced in this paper, makes the evolution of sea quark densities more distinctive than what we obtained in [17]. Two bounda...

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“…In continuation of our previous work [4] we add a gluon cloud to the χQM whilst we use an effective lagrangian at low Q 2 values. We resort to a constituent quark model to extract parton densities inside the proton.…”

Section: Introductionmentioning

confidence: 99%

Gluon parton density in the chiral quark model

Mirjalili

Yazdanpanah

Ghorbani

et al. 2010

Nuclear Physics B - Proceedings Supplements

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Meson Clouds and Dressed Constituent Quarks in the Complete Rg-Improvement Approach

Cited by 10 publications

References 39 publications

LowQ²proton structure function, using gluon and pseudoscalar meson clouds in the constituent quark framework

LowQ²proton structure function, using gluon and pseudoscalar meson clouds in the constituent quark framework

Meson polarized distribution function and mass dependence of the nucleon parton densities

Gluon parton density in the chiral quark model

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Meson Clouds and Dressed Constituent Quarks in the Complete Rg-Improvement Approach

Cited by 10 publications

References 39 publications

LowQ2proton structure function, using gluon and pseudoscalar meson clouds in the constituent quark framework

LowQ2proton structure function, using gluon and pseudoscalar meson clouds in the constituent quark framework

Meson polarized distribution function and mass dependence of the nucleon parton densities

Gluon parton density in the chiral quark model

Contact Info

Product

Resources

About

LowQ²proton structure function, using gluon and pseudoscalar meson clouds in the constituent quark framework

LowQ²proton structure function, using gluon and pseudoscalar meson clouds in the constituent quark framework