Determination of flavor asymmetry for Σ± by the Drell-Yan process

Alberg, Mary; Henley, Ernest M.; Ji, Xiangdong; Thomas, A. W.

doi:10.1016/s0370-2693(96)01272-5

Cited by 27 publications

(33 citation statements)

References 35 publications

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“…This behavior is very different from that obtained in the chiral quark model A( [23], and the octet model [24]. The values for the chiral quark model and the balance model were taken from [25].…”

Section: Flavor Contentmentioning

confidence: 62%

“…The values for the chiral quark model and the balance model were taken from [25]. [24] In order to distinguish between the predictions of the different models and to obtain a better understanding of the non-perturbative structure of QCD, new experiments are needed to measure the flavor asymmetry of hyperons. In particular, the flavor asymmetry of charged Σ hyperons can obtained from Drell-Yan experiments using charged hyperon beams on the proton [24] or by means of backward K ± electroproduction [26].…”

Section: Flavor Contentmentioning

confidence: 99%

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Spin and flavor content of octet baryons

Bijker

Santopinto

2011

J. Phys.: Conf. Ser.

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Abstract. We discuss the spin and flavor content of the proton in an unquenched quark model. It is shown that the inclusion of hadron loops leads automatically to an excess ofd over u and introduces a sizeable contribution of orbital angular momentum to the spin of the proton. Whereas the flavor asymmetry and the orbital angular momentum are dominated by pion loops, the contribution of the sea quark spins to the proton spin arises almost entirely from (excited) vector meson loops. IntroductionIn the constituent quark model (CQM) hadrons are described in terms of system of constituent (or valence) quarks and antiquarks, qqq for baryons and qq for mesons. Despite the success of the quark model there is strong evidence for the existence of exotic degrees of freedom (other than valence quarks) in hadrons, in particular for the need to include the effects of quark-antiquark pairs (hadron loops). The importance of these quark-antiquark configurations (or higher Fock components in baryon wave functions) is evident from measurements of thed/ū asymmetry in the nucleon sea [1], parity-violating electron scattering experiments [2,3], the proton spin crisis [4], as well as from analysis of helicity amplitudes [5] and strong couplings of baryon resonances [6,7].The aim of this contribution is to study the spin and flavor content of the proton in an unquenched quark model in which the effects of quark-antiquark pair creation (uū, dd and ss) are taken into account in an explicit form via a 3 P 0 coupling mechanism [8,9,10]. The numerical results for the flavor asymmetry [9] and the proton spin [8] are analyzed by means of a simple exactly solvable meson-cloud model. Finally, we show some predictions for other octet baryons as well.

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Section: Flavor Contentmentioning

confidence: 62%

Section: Flavor Contentmentioning

confidence: 99%

Spin and flavor content of octet baryons

Bijker

Santopinto

2011

J. Phys.: Conf. Ser.

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“…This behavior is very different from that obtained in the chiral quark model [29], and the octet model A (p) > |A (Ξ 0 )| > A (Σ + ) [30]. The values for the chiral quark model and the balance model were taken from [31].…”

Section: Flavor Asymmetrymentioning

confidence: 80%

“…In particular, the flavor asymmetry of charged Σ hyperons can obtained from Drell-Yan experiments using charged hyperon beams on the proton [30] or by means of backward K ± electroproduction [32].…”

Section: Flavor Asymmetrymentioning

confidence: 99%

The Unquenching of the Quark Model

Santopinto¹,

Bijker²

2011

AIP Conference Proceedings

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“…In order to distinguish between the predictions of the different models and to obtain a better understanding of non-perturbative structure of QCD new experiments are needed to measure the flavor asymmetry of hyperons. In particular, the flavor asymmetry of charged Σ hyperons can obtained from Drell-Yan experiments using charged hyperon beams on the proton [22].…”

Section: Flavor Asymmetrymentioning

confidence: 99%

Structure of the nucleon in the unquenched quark model

Bijker

Santopinto

2010

J. Phys.: Conf. Ser.

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Abstract. We discuss the flavor asymmetry of the nucleon sea and the spin content of the proton in an unquenched quark model. It is shown that the inclusion of hadron loops leads automatically to an excess ofd overū and introduces a sizeable contribution of orbital angular momentum to the spin of the proton and the Λ hyperon. Special attention is paid to the symmetries of the unquenched quark model. IntroductionOne of the challenges of hadronic physics is to understand the structure of the nucleon and its excited states in terms of effective degrees of freedom and, at a more fundamental level, the emergence of these effective degrees of freedom from QCD, the underlying theory of quarks and gluons [1]. The constituent quark model (CQM) is an effective model that has been very successful in explaining hadron properties in terms of system of constituent quarks and antiquarks, qqq for baryons and qq for mesons. Nevertheless, there is compelling evidence for the existence of exotic degrees of freedom (other than valence quarks) in hadrons, in particular for the need to include the effects of quark-antiquark pair creation. The importance of quarkantiquark configurations (or higher Fock components in baryon wave functions) is evident from measurements of thed/ū asymmetry in the nucleon sea [2], parity-violating electron scattering experiments [3,4], the proton spin crisis [5], as well as analysis of helicity amplitudes [6] and strong couplings of baryon resonances [7,8].The aim of this contribution is to study the flavor asymmetry and the spin of the proton in an unquenched quark model in which the effects of quark-antiquark pair creation (uū, dd and ss) are taken into account in an explicit form via a 3 P 0 coupling mechanism [9]. In addition, we show some predictions for the other octet baryons.

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Determination of flavor asymmetry for Σ± by the Drell-Yan process

Abstract: We propose a flavor asymmetry in the light quark sea of Σ ± , which can be measured in Drell-Yan experiments using charged hyperon beams on proton and deuteron targets. Such a measurement would help to reinforce the presence of pseudoscalar mesons in a quark model of baryons.

Cited by 27 publications

References 35 publications

Spin and flavor content of octet baryons

Spin and flavor content of octet baryons

The Unquenching of the Quark Model

Structure of the nucleon in the unquenched quark model

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