Spin and flavor strange quark content of the nucleon

Abstract

Several spin and flavor dependent parameters characterizing the strangeness content of the nucleon have been calculated in the chiral constituent quark model with configuration mixing (χCQM config ) which is known to provide a satisfactory explanation of the "proton spin crisis" and related issues. In particular, we have calculated the strange spin polarization ∆s, the strangeness contribution to the weak axial vector couplings ∆ 8 etc., strangeness contribution to the magnetic moments µ(p) s etc., the strange quark flavor fraction f s , the strangeness dependent quark flavor whereas a recent phenomenology study with lattice inputs [7] also predicts a very small value for the strange magnetic moment, µ(p) s = −0.046 ± 0.19µ N . In the naive constituent quark model (CQM) [8,9,10], µ(p) s is predicted to be zero. The broader question of contribution of strangeness in the nucleon has also been discussed by several authors recently [11]. It is widely recognized that a knowledge about the strangeness content of the nucleon would undoubtedly provide vital clues to the non-perturbative aspects of QCD.The existence of strangeness in the nucleon has been indicated in the context of low energy experiments [12,13] whereas it has been observed in the deep inelastic scattering (DIS) experiments [14,15,16,17]. In the context of DIS, the strange spin polarization of the nucleon [18] looks to be well established through the measurements of polarized structure functions of the nucleon [15,16,17]. Apart from the observations of DIS data regarding strangeness dependent spin polarization functions, several interesting facts have also been revealed regarding the quark flavor distribution functions in the DIS experiments.In particular, the NuSea Collaboration −0.053 . In the context of low energy experiments, the large pion-nucleon sigma term value [13] indicating non zero strange quark flavor fraction f s is also indicative of the presence of strange quarks in the nucleon although there is no consensus regarding the various mechanisms which can contribute to f s [20]. Therefore, the indications of the strange quark degree of freedom in DIS as well as low energy experiments provide a strong motivation to examine the strangeness 2 contribution to the nucleon thereby giving vital clues to the non-perturbative effects of QCD.One may think that the strangeness content of the nucleon perhaps can be obtained through the generation of "quark sea" perturbatively from the quark-pair production by gluons. However, this kind of "sea" is symmetric w.r.t.ū andd [21], negated by the observed value ofū −d asymmetry [19]. Therefore, one has to consider the "quark sea" produced by the non-perturbative mechanism. One such model which can yield an adequate description of the "quark sea" generation through the chiral fluctuations is the chiral constituent quark model (χCQM) [22] which is not only successful in giving a satisfactory explanation of "proton spin crisis" [23] but is also able to account for the violation of Gottfried Sum Rule [21,2...

Nucleon form factors, generalized parton distributions and quark angular momentum

“…Results obtained before 2000 are typically an order of magnitude larger than the lattice results (23), whereas more recent calculations, e.g. in [72,73,74], provide results in fair agreement with them.…”

Masses and magnetic moments of triple heavy flavour baryons in hypercentral model

“…Though considerable amount of data on the properties of the single heavy baryons [6,9,10], and on the light heavy flavour baryons [11][12][13] are available in literature, only sparse attention has been paid to the spectroscopy of double and triple heavy flavour baryons, perhaps mainly due to the lack of experimental incentives [5].…”

Electromagnetic and axial-vector form factors of the quarks and nucleon

“…where qq ′ + q ′ constitute the sea quarks [91][92][93][94][95][98][99][100][101][102][103][104][105][106][107][108]. The GB field can be expressed in terms of the GBs and their transition probabilities as…”