Relativistic effects on the neutron charge form factor in the constituent quark model

Abstract

The neutron charge form factor GEn(Q**2) is investigated within a constituent quark model formulated on the light-front. It is shown that, if the quark initial motion is neglected in the Melosh rotations, the Dirac neutron form factor F1n(Q**2)$receivesarelativisticcorrectionwhichcancelsexactlyagainsttheFoldyterminGEn(Q\ast \ast 2),asithasbeenrecentlyarguedbyIsgur.Moreover,atthesamelevelofapproximationtheratiooftheprotontoneutronmagneticformfactorsGMp(Q\ast \ast 2)/GMn(Q\ast \ast 2)isstillgivenbythenaiveSU(6)-symmetryexpectation,-3/2.However,itisalsoshownthatthefullMeloshrotationsbreakSU(6)symmetry,givingrisetoGEn(Q\ast \ast 2)=/0andGMp(Q\ast \ast 2)/GMn(Q\ast \ast 2)=/-3/2evenwhenaSU(6)-symmetriccanonicalwavefunctionisassumed.ItturnsoutthatrelativisticeffectsalonecannotexplainsimultaneouslytheexperimentaldataonGEn(Q\ast \ast 2)$ and GMp(Q**2)/GMn(Q**2).

arXiv commentfinal version with one minor correction and updated references; to appear in Physics Letters B

References in corpus (2)

• Interpreting the Neutron's Electric Form Factor: Rest Frame Charge Distribution or Foldy Term?
• Isgur-Wise form factors of heavy baryons within a light-front constituent quark model

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