Measurement of the Formation Rate of Muonic Hydrogen Molecules
MuCap Collaboration, V. A. Andreev, T. I. Banks, R. M. Carey, T. A. Case, S. M. Clayton, K. M. Crowe, J. Deutsch, J. Egger, S. J. Freedman, V. A. Ganzha, T. Gor… 展开作者
MuCap Collaboration, V. A. Andreev, T. I. Banks, R. M. Carey, T. A. Case, S. M. Clayton, K. M. Crowe, J. Deutsch, J. Egger, S. J. Freedman, V. A. Ganzha, T. Gorringe, F. E. Gray, D. W. Hertzog, M. Hildebrandt, P. Kammel, B. Kiburg, S. Knaack, P. A. Kravtsov, A. G. Krivshich, B. Lauss, K. R. Lynch, E. M. Maev, O. E. Maev, F. Mulhauser, C. Petitjean, G. E. Petrov, R. Prieels, G. N. Schapkin, G. G. Semenchuk, M. A. Soroka, V. Tishchenko, A. A. Vasilyev, A. A. Vorobyov, M. E. Vznuzdaev, P. Winter
备注：
12 pages, 6 figures, to be submitted to Phys. Rev. C
Background: The rate λ_ppμ characterizes the formation of ppμ molecules in collisions of muonic pμ atoms with hydrogen. In measurements of the basic weak muon capture reaction on the proton to determine the pseudoscalar coupling g_P, capture occurs from both atomic and molecular states. Thus knowledge of λ_ppμ is required for a correct interpretation of these experiments.
Purpose: Recently the MuCap experiment has measured the capture rate Λ_S from the singlet pμ atom, employing a low density active target to suppress ppμ formation (PRL 110, 12504 (2013)). Nevertheless, given the unprecedented precision of this experiment, the existing experimental knowledge in λ_ppμ had to be improved.
Method: The MuCap experiment derived the weak capture rate from the muon disappearance rate in ultra-pure hydrogen. By doping the hydrogen with 20 ppm of argon, a competing process to ppμ formation was introduced, which allowed the extraction of λ_ppμ from the observed time distribution of decay electrons.
Results: The ppμ formation rate was measured as λ_ppμ= (2.01 +- 0.06(stat) +- 0.03(sys)) 10^6 s^-1. This result updates the λ_ppμ value used in the above mentioned MuCap publication.
Conclusions: The 2.5x higher precision compared to earlier experiments and the fact that the measurement was performed at nearly identical conditions to the main data taking, reduces the uncertainty induced by λ_ppμ to a minor contribution to the overall uncertainty of Λ_S and g_P, as determined in MuCap. Our final value for λ_ppμ shifts Λ_S and g_P by less than one tenth of their respective uncertainties compared to our results published earlier.
Non-Perturbative Relativistic Calculation of the Muonic Hydrogen Spectrum
通过精确的、非微扰的数值解，考虑了有限尺寸的库仑力和真空极化，研究了μ子氢2 P ^{F=2}_{3/2}到2S^{F=1}_{1/2}的跃迁.结果与早期的微扰计算（主要）Borie，Martynenko，和Pachucki;和实验结果最近提出的Pohl等人，其中这种比较被解释为需要从电子散射和电子氢分析中获得的质子电荷半径进行修改。我们发现微扰和非微扰计算之间没有显着的差异，并提出我们的结果作为微扰方法的确认。
