The nucleon magnetic form factors in the unphysical region, i.e., for time-like Q2 but below the NN̄ threshold, have been obtained by means of dispersion relations in a model-independent way, without any bias towards expected resonances. Space-like and time-like data have been employed, along with a regularization unfolding method to solve the integral equation. Remarkably, resonance structures with peaks for the ρ(770) and ρ′(1600) and a structure near the NN̄ threshold are automatically generated. The obtained ρ has a much larger width, whose significance is explored. No evidence is found for a peak at the Φ mass, in spite of the expectation that such a peak exists when there is a sizeable polarized ss̄ content in the vector current of the nucleon.
Nucleon time-like form factors below the NN̄ threshold
Pacetti S.
Membro del Collaboration Group
;Srivastava Y.
1999
Abstract
The nucleon magnetic form factors in the unphysical region, i.e., for time-like Q2 but below the NN̄ threshold, have been obtained by means of dispersion relations in a model-independent way, without any bias towards expected resonances. Space-like and time-like data have been employed, along with a regularization unfolding method to solve the integral equation. Remarkably, resonance structures with peaks for the ρ(770) and ρ′(1600) and a structure near the NN̄ threshold are automatically generated. The obtained ρ has a much larger width, whose significance is explored. No evidence is found for a peak at the Φ mass, in spite of the expectation that such a peak exists when there is a sizeable polarized ss̄ content in the vector current of the nucleon.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
