\topheading{Native PDF sets}
\label{olderPDFs}

MCFM contains a native implementation of a number of PDF sets, such that
the use of LHAPDF is not required.  In this mode, one can choose from 
collection of parton distribution functions that are included with
MCFM.  The most recent distributions, together with their associated $\alpha_s(M_Z)$
values, are given in \ref{pdlabelrecent}.
Note that,  due to the memory requirements for
using the NNPDF sets, in OpenMP operation it is usually necessary to increase
the value of the environment variable {\tt OMP\_STACKSIZE} to avoid
segmentation faults.
%
\begin{table}[h]
\begin{center}
\begin{tabular}{|c|c|c|c|}
\hline
{\tt pdlabel}  & $\alpha_s(M_Z)$ & order & reference \\
\hline
{\tt mstw8lo}  & 0.1394 & 1     & \cite{Martin:2009iq} \\
{\tt mstw8nl}  & 0.1202 & 2     & \cite{Martin:2009iq} \\
{\tt mstw8nn}  & 0.1171 & 3     & \cite{Martin:2009iq} \\
{\tt MMHT\_lo}  & 0.135  & 1     & \cite{Harland-Lang:2014zoa} \\
{\tt MMHT\_nl}  & 0.120  & 2     & \cite{Harland-Lang:2014zoa} \\
{\tt MMHT\_nn}  & 0.118  & 3     & \cite{Harland-Lang:2014zoa} \\
\hline
{\tt CT10.00}  & 0.118  & 2     & \cite{Lai:2010vv} \\
{\tt CT14.LL}  & 0.130  & 1     & \cite{Dulat:2015mca} \\
{\tt CT14.NL}  & 0.118  & 2     & \cite{Dulat:2015mca} \\
{\tt CT14.NN}  & 0.118  & 3     & \cite{Dulat:2015mca} \\
{\tt CT14qed}  & 0.118  & 2     & \cite{Schmidt:2015zda} \\
\hline
{\tt NN2.3NL}  & 0.118  & 2     & \cite{Ball:2012cx} \\
{\tt NN2.3NN}  & 0.118  & 3     & \cite{Ball:2012cx} \\
{\tt NN3.0LO}  & 0.118  & 1     & \cite{Ball:2014uwa} \\
{\tt NN3.0NL}  & 0.118  & 2     & \cite{Ball:2014uwa} \\
{\tt NN3.0NN}  & 0.118  & 3     & \cite{Ball:2014uwa} \\
\hline
\end{tabular}
\end{center}
\caption{Modern PDF sets that are available in the code,
their corresponding values of $\alpha_s(M_Z)$ and order of running,
and a reference to the paper
that describes their origin.  Further sets, of a more historical nature, are listed in \ref{olderPDFs}.
\label{pdlabelrecent}}
\end{table}

The availability of a number of historical PDF sets is retained in the code.  These should
typically not be used in modern analyses, but they may be helpful for comparison with
older codes or in specialized cases.
These distributions, together with their associated $\alpha_S(M_Z)$
values, are given in Tables~\ref{pdlabelmrs} and~\ref{pdlabelcteq}. 
For the older distributions, where the
coupling was specified by $\Lambda$ this requires 
some calculation and/or guesswork.

\begin{table}[h]
\begin{center}
\begin{tabular}{|c|c|c||c|c|c|}
\hline
{\tt mrstqed}  & 0.1205       & hep-ph/0411040 &
{\tt mrs02nl}  & 0.1197       & \mrstohtwo \\
{\tt mrs02nn}  & 0.1154       & \mrstohtwo &
{\tt mrs4nf3}  & 0.1083       & \mrstff \\
{\tt mrs4lf3}  & 0.1186       & \mrstff &
{\tt mrs4nf4}  & 0.1153       & \mrstff \\
{\tt mrs4lf4}  & 0.1251       & \mrstff &
{\tt mrs0119}  & 0.119        & \mrstohone \\
{\tt mrs0117}  & 0.117        & \mrstohone &
{\tt mrs0121}  & 0.121        & \mrstohone \\
{\tt mrs01\_j} & 0.121        & \mrstohone &
{\tt mrs01lo}  & 0.130        & \mrstohtwofirst \\ 
{\tt mrs99\_1} & 0.1175       & \mrsninenine &
{\tt mrs99\_2} & 0.1175       & \mrsninenine \\
{\tt mrs99\_3} & 0.1175       & \mrsninenine &
{\tt mrs99\_4} & 0.1125       & \mrsninenine \\    
{\tt mrs99\_5} & 0.1225       & \mrsninenine &
{\tt mrs99\_6} & 0.1178       & \mrsninenine \\    
{\tt mrs99\_7} & 0.1171       & \mrsninenine &
{\tt mrs99\_8} & 0.1175       & \mrsninenine \\    
{\tt mrs99\_9} & 0.1175       & \mrsninenine &
{\tt mrs9910}  & 0.1175       & \mrsninenine \\    
{\tt mrs9911}  & 0.1175       & \mrsninenine &
{\tt mrs9912}  & 0.1175       & \mrsninenine \\    
{\tt mrs98z1}  &  0.1175      & \mrsnineeight &  
{\tt mrs98z2}  &  0.1175      & \mrsnineeight \\ 
{\tt mrs98z3}  &  0.1175      & \mrsnineeight &  
{\tt mrs98z4}  &  0.1125      & \mrsnineeight \\  
{\tt mtungb1}  &  0.109       & \mrsnineeight &
{\tt mrs98z5}  &  0.1225      & \mrsnineeight \\   
{\tt mrs96r1}  &  0.113       & \mrsninesix &    
{\tt mrs96r2}  &  0.120       & \mrsninesix \\  
{\tt mrs96r3}  &  0.113       & \mrsninesix &   
{\tt mrs96r4}  &  0.120       & \mrsninesix \\   
{\tt mrs95ap}  &  0.1127      & \mrsninefive &
{\tt mrs95\_g} &  0.1148      & \mrsninefive \\
{\tt hmrs90e}  &  0.09838     & \hmrs & 
{\tt hmrs90b}  &  0.10796     & \hmrs \\
\hline
\end{tabular}
\end{center}
\caption{Historical MRS-type pdf sets, their corresponding values of
$\alpha_S(M_Z)$ and a reference to the paper or preprint that
describes their origin.
\label{pdlabelmrs}}
\end{table}
\begin{table}[h]
\begin{center}
\begin{tabular}{|c|c|c||c|c|c|}
\hline
               &              & &
{\tt cteq66m}  &  0.118       & \cteqsixsixm \\
{\tt cteq61m}  &  0.118       & \cteqsixonem &
{\tt cteq6\_m} &  0.118       & \cteqsix \\
{\tt cteq6\_d} &  0.118       & \cteqsix &
{\tt cteq6\_l} &  0.118       & \cteqsix \\
{\tt cteq6l1}  &  0.130       & \cteqsix &
{\tt cteq5hq}  &  0.118       & \cteqfive \\
{\tt cteq5f3}  &  0.106       & \cteqfive &
{\tt cteq5f4}  &  0.112       & \cteqfive \\
{\tt cteq5\_m} &  0.118       & \cteqfive &
{\tt cteq5\_d} &  0.118       & \cteqfive \\
{\tt cteq5\_l} &  0.127       & \cteqfive & 
{\tt cteq5l1}  &  0.127       & \cteqfive \\
{\tt cteq5hj}  &  0.118       & \cteqfive &
{\tt cteq5m1}  &  0.118       & \cteqfive \\
{\tt ctq5hq1}  &  0.118       & \cteqfive &
{\tt cteq4a5}  &  0.122       & \cteqfour \\
{\tt cteq4hj}  &  0.116       & \cteqfour &
{\tt cteq4lq}  &  0.114       & \cteqfour \\
{\tt cteq4\_m} &  0.116       & \cteqfour &
{\tt cteq4\_d} &  0.116       & \cteqfour \\
{\tt cteq4\_l} &  0.132       & \cteqfour &
{\tt cteq4a1}  &  0.110       & \cteqfour \\
{\tt cteq4a2}  &  0.113       & \cteqfour &
{\tt cteq4a3}  &  0.116       & \cteqfour \\
{\tt cteq4a4}  &  0.119       & \cteqfour &
{\tt cteq3\_m} &  0.112       & \cteqthree \\
{\tt cteq3\_l} &  0.112       & \cteqthree &
{\tt cteq3\_d} &  0.112       & \cteqthree \\
\hline
\end{tabular}
\end{center}
\caption{Historical CTEQ-type pdf sets, their corresponding values of
$\alpha_S(M_Z)$ and a reference to the paper or preprint that
describes their origin.
\label{pdlabelcteq}}
\end{table}
