Proton Form Factors and Related Processes in BaBar by ISR

BaBar has measured with unprecedented accuracy [Formula: see text] from the threshold up to [Formula: see text], finding out an unexpected cross section, with plateaux and drops. In particular it is well established a sharp drop near threshold, where evidence for structures in multihadronic channels has also been found. Other unexpected and spectacular features of the Nucleon form factors are reminded, the behaviour of space-like [Formula: see text] and the neutron time-like form factors.

Download Full-text

Time-Like Proton Form Factors in Initial State Radiation Process

10.20944/preprints202112.0030.v1 ◽

2021 ◽

Author(s):

Dexu Lin ◽

Alaa Dbeyssi ◽

Frank Maas

Keyword(s):

Cross Section ◽

Experimental Studies ◽

Form Factors ◽

Initial State Radiation ◽

Initial State ◽

Radiation Process ◽

Proton Form ◽

Born Cross Section ◽

State Radiation ◽

Proton Form Factors

The measurements of the proton electromagnetic form factors in the time-like region using the initial state radiation technique are reviewed. Recent experimental studies have shown that initial state radiation processes at high luminosity electron-positron colliders can be effectively used to probe the electromagnetic structure of hadrons. The BABAR experiment at the B-factory PEP-II in Stanford and the BESIII experiment at the $\tau$-charm factory BEPC-II in Beijing have measured the time-like form factors of the proton using the initial state radiation process $e^{+}e^{-}\to pbar{p}\gamma$. The two kinematical regions where the photon is emitted from the initial state at small and large polar angles have been investigated. In the first case the photon is in the region not covered by the detector acceptance and is not detected. The Born cross section and the proton effective form factor have been measured over a wide and continuous range of the the momentum transfer squared $q^2$ from threshold up to ~42 (GeV/c)$^2$. The ratio of electric and magnetic form factors of the proton has been also determined. In this report, the theoretical aspect and the experimental studies of the initial state radiation process $e^{+}e^{-}\to p\bar{p}\gamma$ are described. The measurements of the Born cross section and the proton form factors obtained in these analyses near the threshold region and in the relatively large $q^2$ region are examined. The experimental results are compared to the predictions from theory and models. Their impact on our understanding of the nucleon structure is discussed.

Download Full-text

THEORETICAL AND EXPERIMENTAL REVIEW ON PROTON FORM FACTORS

International Journal of Modern Physics Conference Series ◽

10.1142/s2010194514604232 ◽

2014 ◽

Vol 35 ◽

pp. 1460423

Author(s):

RINALDO BALDINI FERROLI ◽

SIMONE PACETTI

Keyword(s):

Golden Age ◽

Form Factors ◽

Point Of View ◽

The Other ◽

Theoretical Point ◽

Jefferson Lab ◽

Proton Form ◽

Other Hand ◽

Nucleon Form Factors ◽

Proton Form Factors

During the last three lustra nucleon form factors experiments have lived a golden age, full of interesting results, that likely will continue and culminate when new data will come from BESIII, SND, CMD3 and PANDA, in the time-like region and, Jefferson Lab and A1 in the space-like region. On the other hand, from theoretical point of view, mainly concerning the possibility of descriptions in all kinematical regions, no great breakthrough has been made.

Download Full-text