include/apfel/gammak.h

0001 //
0002 // APFEL++ 2017
0003 //
0004 // Author: Valerio Bertone: valerio.bertone@cern.ch
0005 //
0006
0007 #pragma once
0008
0009 namespace apfel
0010 {
0011   /**
0012    * @name Cusp anomalous dimension.
0013    * Coefficients of the &gamma;<SUB>K</SUB> anomalous dimension. The
0014    * expressions up to O(&alpha;<SUB>s</SUB><SUP>3</SUP>) are taken
0015    * from eq. (59) https://arxiv.org/pdf/1705.07167.pdf. While the
0016    * expressions at O(&alpha;<SUB>s</SUB><SUP>4</SUP>) are taken from
0017    * Eq. (6.3) of https://arxiv.org/pdf/1911.10174.pdf or Eq. (6) of
0018    * https://arxiv.org/pdf/2002.04617v2.pdf
0019    * @note All the expressions do not include an overall factor
0020    * C<SUB>F</SUB> or C<SUB>A</SUB>.
0021    */
0022   ///@{
0023   /// &alpha;<SUB>s</SUB> term
0024   double gammaK0();
0025
0026   /// &alpha;<SUB>s</SUB><SUP>2</SUP> term
0027   double gammaK1(int const& nf);
0028
0029   /// &alpha;<SUB>s</SUB><SUP>3</SUP> term
0030   double gammaK2(int const& nf);
0031
0032   /// &alpha;<SUB>s</SUB><SUP>4</SUP> term
0033   double gammaK3(int const& nf);
0034
0035   /// &alpha;<SUB>s</SUB><SUP>4</SUP> correction to the quark
0036   /// anonalous dimension needed to obtain the gluon anomalous
0037   /// dimension (neglected for now).
0038   double gammaK3gmq(int const& nf);
0039   ///@}
0040 }