scholarly journals MEASUREMENT OF THE PROTON ELECTROMAGNETIC FORM FACTORS AT BABAR

2014 ◽  
Vol 35 ◽  
pp. 1460425
Author(s):  
V. P. DRUZHININ ◽  
Keyword(s):  
Center Of Mass ◽  
Form Factors ◽  
Mass Range ◽  
Initial State Radiation ◽  
Electromagnetic Form Factors ◽  
Initial State ◽  
State Radiation ◽  
Radiation Technique ◽  
Babar Detector ◽  
Integrated Luminosity

The process [Formula: see text] has been studied in the [Formula: see text] mass range from threshold to 6.5 GeV/c2 using the initial-state-radiation technique with both detected and undetected photon. The analysis is based on 469 fb-1 of integrated luminosity collected with the BABAR detector at the PEP-II collider at e+e- center-of-mass energies near 10.6 GeV.

scholarly journals BESIII results on time-like baryon form factors

2019 ◽  
Vol 218 ◽  
pp. 04002
Author(s):  
Alaa Dbeyssi
Keyword(s):  
Form Factor ◽  
Center Of Mass ◽  
Form Factors ◽  
Initial State Radiation ◽  
Proton Form Factor ◽  
Electromagnetic Form Factors ◽  
Initial State ◽  
Data Set ◽  
Preliminary Results ◽  
State Radiation

This contribution reports on the recent measurements of baryon electromagnetic form factors at the BESIII experiment in Beijing. The Beijing e+e − collider BEPCII is a double-ring symmetric collider running at $ \sqrt s $ between 2.0 and 4.6 GeV. Baryon electromagnetic form factors can be measured at BESIII in direct e+e−-annihilation and in initial state radiation processes. Based on the data collected by the BESIII detector at 12 center of mass energies between 2.23 and 3.67 GeV, the measured $ \mathop e\nolimits^ + \mathop e\nolimits^ - \to \mathop p\limits^ - p $ cross section and the time-like proton form factor are presented. Preliminary results from the analysis of the initial state radiation process $ \mathop e\nolimits^ + \mathop e\nolimits^ - \to \mathop p\limits^ - p\gamma $ using a data set of 7.408 fb−1 collected at center of mass energies between 3.773 and 4.6 GeV, are also shown. The cross sections for $ \mathop e\nolimits^ + \mathop e\nolimits^ - \to \mathop {\mathop \Lambda \nolimits_c^ - }\limits^ - \mathop \Lambda \nolimits_c^ + $ and $ \mathop e\nolimits^ + \mathop e\nolimits^ - \to \mathop \Lambda \limits^ - \Lambda $ are measured near threshold with unprecedented precision. Preliminary results on the first measurement of the ^c form factor ratio |GE|/|GM| are also given. Ongoing analysis based on the high luminosity energy scan from 2015 and from radiative return at different $ \sqrt s $ are also described.

scholarly journals Time-like Proton Form Factors with Initial State Radiation Technique

Symmetry ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 91
Author(s):  
Dexu Lin ◽  
Alaa Dbeyssi ◽  
Frank Maas
Keyword(s):  
Experimental Studies ◽  
Form Factors ◽  
Initial State Radiation ◽  
Initial State ◽  
Radiation Process ◽  
Electron Positron ◽  
Born Cross Section ◽  
State Radiation ◽  
Radiation Technique ◽  
Proton Form Factors

Electromagnetic form factors are fundamental quantities describing the internal structure of hadrons. They can be measured with scattering processes in the space-like region and annihilation processes in the time-like region. The two regions are connected by crossing symmetry. 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 BEPCII (an electron positron collider in the τ-charm mass region) in Beijing have measured the time-like form factors of the proton using the initial state radiation process e+e−→pp¯γ. 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 q2 from the 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−→pp¯γ 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 q2 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.

scholarly journals Hadron Form Factors at BESIII

2018 ◽  
Vol 46 ◽  
pp. 1860027
Author(s):  
Zhaoxia Meng
Keyword(s):  
Cross Section ◽  
Center Of Mass ◽  
Polar Angle ◽  
Form Factors ◽  
Angle Distribution ◽  
Initial State ◽  
Fundamental Information ◽  
Born Cross Section ◽  
Effective Form ◽  
State Radiation

Form factors of hadron provide fundamental information about its structure and dynamics. They constitute a rigorous test of non-perturbative QCD as well as of phenomenological models. Based on data samples collected with BESIII detector at BEPCII collider, born cross section of [Formula: see text] and proton effective form factors are measured at 12 center-of-mass energies between 2.2324 and 3.671 GeV. The ratio [Formula: see text]s are extracted by fitting polar angle distribution of proton for data samples with large statistics. For data between 3.773 and 4.6 GeV, we use initial state radiation (ISR) method to study [Formula: see text] by tagged or un-tagged ISR photon, where the pair cross section, effective form factors and [Formula: see text]s are obtained from proton pair threshold to about 3 GeV. For [Formula: see text] and [Formula: see text], the pair cross section and [Formula: see text] form factors are measured near threshold. With data scanned in 2015 from 2-3.08 GeV, charged Kaon pair cross section and form factors are measured at 21 center-of-mass energies.

scholarly journals J/ψproduction via initial state radiation ine+e−→μ+μ−γat ane+e−center-of-mass energy near 10.6 GeV

2004 ◽  
Vol 69 (1) ◽  
Author(s):  
B. Aubert ◽  
R. Barate ◽  
D. Boutigny ◽  
J.-M. Gaillard ◽  
A. Hicheur ◽  
...  
Keyword(s):  
Center Of Mass ◽  
Initial State Radiation ◽  
Mass Energy ◽  
Initial State ◽  
Center Of Mass Energy ◽  
State Radiation

scholarly journals Dark initial state radiation and the kinetic mixing portal

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Thomas G. Rizzo
Keyword(s):  
Cross Sections ◽  
Gauge Coupling ◽  
Mass Range ◽  
Initial State Radiation ◽  
Microwave Background ◽  
Initial State ◽  
Complex Scalar ◽  
Dark Photon ◽  
State Radiation ◽  
Relic Density

Abstract Data from Planck measurements of the cosmic microwave background (CMB) place important constraints on models with light dark matter (DM) and light mediators especially when both lie in the mass range below ∼ 1 GeV. In models involving kinetic mixing where the dark photon acts as the mediator, these constraints are easily satisfied and the appropriate DM relic density achievable if the DM is, e.g., a complex scalar, where p-wave annihilation occurs, or is the lighter component of a split pseudo-Dirac state where co-annihilation dominates. In both of these cases, although higher order in the dark gauge coupling, gD, the corresponding annihilation processes including dark photon initial state radiation (ISR) will be dominantly s-wave with essentially temperature independent cross sections. The rates for these dark ISR associated processes, though not yielding cross sections large enough to contribute to the relic density, can still run into possible conflicts with the bounds arising from the CMB. In this paper we perform a preliminary study of the present and potential future constraints that the CMB imposes on the parameter spaces for both of these scenarios due to the existence of this dark ISR. Further analyses of the effects of dark ISR in DM annihilation is clearly warranted.

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