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Singlet structure function F1 in double-logarithmic approximation
Monday 03 December 2018, 04:30pm - 05:30pm
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Description: The conventional ways to calculate the perturbative component of the DIS singlet structure function F1 involve approaches based on BFKL which account for the single-logarithmic contributions accompanying the Born factor 1 / x. In contrast, we account for the double-logarithmic (DL) contriutions unrelated to 1 / x and because of that they were disregarded as negligibly small. We calculate the singlet F1 in the double-logarithmic approximation (DLA) and account at the same time for the running ?? effects. We start with a total resummation of both quark and gluon DL contributions and obtain the explicit expression for ?1 in DLA. Then, applying the saddle-point method, we calculate the small-x asymptotics of ?1 , which proves to be of the Regge form with the leading singularity ?0=1.066 . Its large value compensates for the lack of the factor 1 / x in the DLA contributions. Therefore, this Reggeon can be identified as a new Pomeron, which can be quite important for the description of all QCD processes involving the vacuum (Pomeron) exchanges at very high energies. We prove that the expression for the small-x asymptotics of ?1 scales: it depends on a single variable ?2/?2 only instead of x and ?2 separately. Finally, we show that the small-x asymptotics reliably represent ?1 at ?≤10−6 .
Location Dipertimento di Fisica, M.S. Angelo 2N22