How Bright is the Proton? A Precise Determination of the Photon Parton Distribution Function.
How Bright is the Proton? A Precise Determination of the Photon Parton Distribution Function.
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DOI：
10.1103/physrevlett.117.242002
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发表时间：
2016-07
影响因子：
8.6
通讯作者：
A. Manohar;P. Nason;G. Salam;G. Zanderighi
中科院分区：
文献类型：
--
作者：
A. Manohar;P. Nason;G. Salam;G. Zanderighi
近年来，很明显，对质子中光子分布的准确了解是很重要的，特别是对于大型强子对撞机的一系列物理研究。我们展示了光子部分子分布函数（PDF）如何以模型无关的方式确定，使用电子-质子（ep）散射数据，有效地将ep→e+X过程视为电子散射质子的光子场。为此，我们考虑一个假想的，超越标准模型的过程，具有一个味道变化的光子轻子顶点。我们用两种方法来写它的横截面：一种是用质子结构函数，另一种是用光子分布。要求它们的等价性产生光子分布作为质子结构函数的积分。由于ep数据的良好精度，我们在很宽的动量分数范围内将光子PDF限制在1%-2%的水平。
It has become apparent in recent years that it is important, notably for a range of physics studies at the Large Hadron Collider, to have accurate knowledge on the distribution of photons in the proton. We show how the photon parton distribution function (PDF) can be determined in a model-independent manner, using electron-proton (ep) scattering data, in effect viewing the ep→e+X process as an electron scattering off the photon field of the proton. To this end, we consider an imaginary, beyond the Standard Model process with a flavor changing photon-lepton vertex. We write its cross section in two ways: one in terms of proton structure functions, the other in terms of a photon distribution. Requiring their equivalence yields the photon distribution as an integral over proton structure functions. As a result of the good precision of ep data, we constrain the photon PDF at the level of 1%-2% over a wide range of momentum fractions.