Pion form factor in QCD at intermediate momentum transfers

被引:137
作者
Braun, VM [1 ]
Khodjamirian, A
Maul, M
机构
[1] Univ Regensburg, Inst Theoret Phys, D-93040 Regensburg, Germany
[2] Univ Wurzburg, Inst Theoret Phys, D-97074 Wurzburg, Germany
[3] NORDITA, DK-2100 Copenhagen O, Denmark
来源
PHYSICAL REVIEW D | 2000年 / 61卷 / 07期
关键词
D O I
10.1103/PhysRevD.61.073004
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present a quantitative analysis of the electromagnetic pion form factor in the light-cone sum rule approach, including radiative corrections and higher-twist effects. The comparison to the existing data favors the asymptotic profile of the pion distribution amplitude and allows us to estimate the deviation: [integral dulu phi(pi)(u)]/[integral dulu phi(pi)(as)(u)] = 1.1+/- 0.1 at the scale of 1 GeV. Special attention is paid to the precise definition and interplay of soft and hard contributions at intermediate momentum transfer, and to the matching of the sum rule to the perturbative QCD prediction. We observe a strong numerical cancellation between the soft (end-point) contribution and power-suppressed hard contributions of higher twist, so that the total nonperturbative correction to the usual PQCD result turns out to be of the order of 30% for Q(2) similar to 1 GeV2.
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页数:19
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