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.

Manohar, A., Nason, P., Salam, G., Zanderighi, G. (2016). How Bright is the Proton? A Precise Determination of the Photon Parton Distribution Function. PHYSICAL REVIEW LETTERS, 117(24) [10.1103/PhysRevLett.117.242002].

How Bright is the Proton? A Precise Determination of the Photon Parton Distribution Function

NASON, PAOLO;ZANDERIGHI, GIULIA
2016

Abstract

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.
Articolo in rivista - Articolo scientifico
INELASTIC STRUCTURE FUNCTIONS; 3-LOOP SPLITTING FUNCTIONS; QED; CORRECTIONS; NNLO EVOLUTION; PDF; PARTICLES; QCD; SCATTERING; COLLISIONS; IMPACT
English
2016
117
24
242002
none
Manohar, A., Nason, P., Salam, G., Zanderighi, G. (2016). How Bright is the Proton? A Precise Determination of the Photon Parton Distribution Function. PHYSICAL REVIEW LETTERS, 117(24) [10.1103/PhysRevLett.117.242002].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/217866
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