Testing the meson cloud in the nucleon in Drell-Yan processes

Abstract

We discuss the present status of the u d asymmetry in the nucleon and analize the quantities which are best suited to verify the asymmetry. W e nd that the Drell-Yan asymmetry is the quantity insensitive to the valence quark distributions and very sensitive to the avour asymmetry of the sea. We compare the prediction of the meson cloud model with di erent experimental data including the Fermilab E772 data and recent data of the NA51 Collaboration at CERN and make predictions for the planned Drell-Yan experiments. 25.30.Pt, 13.85.Hi Typeset using REVT E X 1

Measurement of the Light Antiquark Flavor Asymmetry in the Nucleon Sea

“…CTEQ, MRS) simply assume a shape ford−ū that accommodates the NMC and NA51 results. It has been suggested [17,18] that including the effects of virtual mesons can account for the observed asymmetry and this appears [19][20][21][22] to be at least qualitatively correct.…”

Mesonic Contributions to the Spin and Flavor Structure of the Nucleon

“…Ito et al, suggested to analyze the logarithmic derivative of the rapidity distribution. Shown is the lit of the K-factor for various quark distributions to the experimental data [86]. ) parametrization [86].…”

“…Shown is the lit of the K-factor for various quark distributions to the experimental data [86]. ) parametrization [86]. Data are taken from Ref.…”

Intrinsic strange distributions in the nucleon from the light-cone models

“…Unlike the five-quark models that lead to an equal distribution for strange and antistrange, this more dynamical model can lead to the s−s asymmetry in the nucleon sea. Although the original meson-baryon model is rather complicated computationally [5,9,11,14,20], we can consider a simple configuration as has been used in Ref. [4].…”

“…For example, in addition to the BHPS result for the intrinsic charm (IC) distributions in the nucleon, there have been some other theoretical calculations using the scalar fivequark and meson-baryon models performed by Pumplin [4] and Hobbs et al [5] in recent years. In the case of intrinsic light quark distributions, some calculations have been performed by Chang and Pang [6] using the BHPS model and there are also a wide range of results from * Electronic address: Maral.Salajegheh@gmail.com the meson cloud model (MCM) [7][8][9][10][11][12][13][14][15][16][17][18][19][20] and chiral quark model (CQM) [21][22][23][24][25][26][27][28] for either polarized or unpolarized distributions. For the extraction of the probabilities of the intrinsic charm quark in the nucleon, we can point to the analyses performed by BHPS [2] using diffractive production of charmed hadrons; by Harris et al [29] using the EMC charm production data [30]; and also some global analyses of parton distribution functions (PDFs) performed so far, including the intrinsic charm contributions in the nucleon [31][32][33].…”