scholarly journals The proton charge radius extracted from the initial-state radiation experiment at MAMI

2021 ◽  
Vol 57 (3) ◽  
Author(s):  
M. Mihovilovič ◽  
P. Achenbach ◽  
T. Beranek ◽  
J. Beričič ◽  
J. C. Bernauer ◽  
...  
Keyword(s):  
Cross Sections ◽  
Charge Radius ◽  
Finite Size ◽  
Initial State Radiation ◽  
Initial State ◽  
External Energy ◽  
Section Data ◽  
Proton Charge ◽  
Proton Charge Radius ◽  
State Radiation

AbstractWe report on a comprehensive reinterpretation of the existing cross-section data for elastic electron-proton scattering obtained by the initial-state radiation technique, resulting in a significantly improved accuracy of the extracted proton charge radius. By refining the external energy corrections we have achieved an outstanding description of the radiative tail, essential for a detailed investigation of the proton finite-size effects on the measured cross sections. This development, together with a novel framework for determining the radius, based on a regression analysis of the cross sections employing a polynomial model for the form factor, led us to a new value for the charge radius, which is $$(0.878 \pm 0.011_\mathrm {stat.}\pm 0.031_\mathrm {sys.}\pm 0.002_\mathrm {mod.})\,\mathrm {fm}$$ ( 0.878 ± 0 . 011 stat . ± 0 . 031 sys . ± 0 . 002 mod . ) fm

scholarly journals e+e−→K+K−π+π−,K+K−π0π0andK+K−K+K−cross sections measured with initial-state radiation

2007 ◽  
Vol 76 (1) ◽  
Author(s):  
B. Aubert ◽  
M. Bona ◽  
D. Boutigny ◽  
Y. Karyotakis ◽  
J. P. Lees ◽  
...  
Keyword(s):  
Cross Sections ◽  
Initial State Radiation ◽  
Initial State ◽  
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.

scholarly journals Measurement of the e+e−→Ks0K±π∓π0 and Ks0K±π∓η cross sections using initial-state radiation

2017 ◽  
Vol 95 (9) ◽  
Author(s):  
J. P. Lees ◽  
V. Poireau ◽  
V. Tisserand ◽  
E. Grauges ◽  
A. Palano ◽  
...  
Keyword(s):  
Cross Sections ◽  
Initial State Radiation ◽  
Initial State ◽  
State Radiation

The Lamb shift in muonic hydrogenThis paper was presented at the International Conference on Precision Physics of Simple Atomic Systems, held at École de Physique, les Houches, France, 30 May – 4 June, 2010.

2011 ◽  
Vol 89 (1) ◽  
pp. 37-45 ◽  
Author(s):  
Randolf Pohl ◽  
Aldo Antognini ◽  
François Nez ◽  
Fernando D. Amaro ◽  
François Biraben ◽  
...  
Keyword(s):  
Charge Radius ◽  
Lamb Shift ◽  
Finite Size ◽  
Muonic Hydrogen ◽  
Energy Splitting ◽  
Atomic Systems ◽  
Proton Charge ◽  
Proton Charge Radius ◽  
Rydberg Constant ◽  
Better Than

The long quest for a measurement of the Lamb shift in muonic hydrogen is over. Last year we measured the 2S 1/2F=1 –2P 3/2F=2 energy splitting (Pohl et al., Nature, 466, 213 (2010)) in μp with an experimental accuracy of 15 ppm, twice better than our proposed goal. Using current QED calculations of the fine, hyperfine, QED, and finite size contributions, we obtain a root-mean-square proton charge radius of rp = 0.841 84 (67) fm. This value is 10 times more precise, but 5 standard deviations smaller, than the 2006 CODATA value of rp. The origin of this discrepancy is not known. Our measurement, together with precise measurements of the 1S–2S transition in regular hydrogen and deuterium, gives improved values of the Rydberg constant, R∞ = 10 973 731.568 160 (16) m–1 and the rms charge radius of the deuteron rd = 2.128 09 (31) fm.

scholarly journals Angular analysis of the e+e- → D(*)D* process near the open-charm threshold using initial-state radiation

2019 ◽  
Vol 202 ◽  
pp. 06008
Author(s):  
Valentina Zhukova
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Center Of Mass ◽  
Initial State Radiation ◽  
Initial State ◽  
Center Of Mass Energy ◽  
Belle Detector ◽  
Section Measurement ◽  
Angular Analysis ◽  
State Radiation

We report new measurement of the exclusive e+e- → D(*)±D*∓ cross sections as a function of center-of-mass energy from the D(∗)±D∗∓ threshold up to $ \sqrt s $ = 6.0 GeV with initial state radiation. The analysis is based on a data sample collected by the Belle detector with an integrated luminosity of 951 fb−1. The accuracy of the cross section measurement is increased by a factor of 2 in comparison with the first Belle study. We have performed the first angular analysis of the e+e- → D∗±D∗∓ process and decomposed this exclusive cross section into three components corresponding to the different D∗ helicities.

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