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hiro98 2020-06-10 13:59:32 +02:00
parent fe41dae00b
commit 6853669e3a
4 changed files with 23 additions and 24 deletions

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@ -60,7 +60,7 @@ results and figures can be found under
\url{https://github.com/vale981/bachelor_thesis/} and more
specifically in the subdirectory \texttt{prog/python/qqgg}.
The file \texttt{monte\_carlo.py} implements all the monte-carlo
The file \texttt{monte\_carlo.py} implements all the Monte Carlo
algorithm related functionality as a module. The file
\texttt{analytical\_xs.org} contains a literate computation notebook
that generates all the results of \cref{chap:mc}. The file

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@ -20,7 +20,7 @@ variable through integration over the remaining variables and then,
keeping the first variable fixed, sampling the other variables in a
likewise manner.
Consider a function \(f\colon x\in\Omega\mapsto\mathbb{R}_{\geq 0}\)
Consider a function \(f\colon x\in\Omega\mapsto\mathbb{R}_{>0}\)
where \(\Omega = [0, 1]\) without loss of generality. Such a function
is proportional to a probability density \(\tilde{f}\). When \(X\) is
a uniformly distributed random variable on~\([0, 1]\) (which can be
@ -84,8 +84,8 @@ efficiency \(\mathfrak{e}\), is given by \cref{eq:impsampeff}.
\int_0^1\frac{g(x)}{B}\cdot\frac{f(x)}{g(x)}\dd{x} = \int_0^1\frac{f(x)}{B}\dd{x} = \frac{A}{B} = \mathfrak{e}\leq 1
\end{equation}
%
The closer the volumes enclosed by \(g\) and \(f\) are to each other,
higher is \(\mathfrak{e}\).
The closer the sizes of volumes enclosed by \(g\) and \(f\) are to
each other, the higher is \(\mathfrak{e}\).
Choosing \(g\) like \cref{eq:primitiveg} and looking back at
\cref{eq:solutionsamp} yields \(y = x\cdot A\), so that the sampling
@ -142,7 +142,7 @@ way is an alternative method of performing \emph{importance sampling}.
\end{equation}
%
The optimal transformation would be the solution of \(y = F(x)\)
(\(F\) being the antiderivative), so that
(\(F\) being the antiderivative of \(f\)), so that
\(f(x(y)) \cdot \dv{x(y)}{y} = 1\). But transforming \(f\) in this way
is the same as solving \cref{eq:takesample} which is a problem that
has been addressed in \cref{sec:hitmiss}. The difference here is, that
@ -243,14 +243,14 @@ distribution \(f\) is required.
Yet another approach is to subdivide the sampling volume \(\Omega\)
into \(K\) sub-volumes \(\Omega_i\subset\Omega\) and then take a
number of samples from each volume proportional to the integral of the
function \(f\) in that volume. This is a method of stratified
function \(f\) in that volume. This is a variant of
\emph{stratified sampling}, with the advantage that it is now possible
to optimize the sampling in each sub-volume independently.
Let \(N\) be the total sample count (\(N\gg 1\)),
\(A_i = \int_{\Omega_i}f(x)\dd{x}\) and \(A=\sum_iA_i\).
Then we can calculate the total efficiency of taking \(N_i=A_i/A \cdot N\)
samples in each is then given by \cref{eq:rstrateff}.
\(A_i = \int_{\Omega_i}f(x)\dd{x}\) and \(A=\sum_iA_i\). The total
efficiency when taking \(N_i=A_i/A \cdot N\) samples in each hypercube
is then given by \cref{eq:rstrateff}.
%
\begin{equation}
\label{eq:rstrateff}
@ -300,12 +300,12 @@ Jacobian.
Using the distribution \cref{eq:distcos} for the variable
\(\cos\theta\) and choosing the polar angle \(\varphi\) uniformly
random, a sample of 4-momenta can be generated and histograms
random, a sample of 4-momenta can be generated and histograms of
observables can be drawn.
The observables considered here are the transverse momentum \(\pt\)
and the pseudo rapidity \(\eta\) which can be computed from 4-momentum
as described in \cref{eq:observables}.
and the pseudo rapidity \(\eta\) which can be computed from the
4-momentum as described in \cref{eq:observables}.
%
\begin{align}
\label{eq:observables}
@ -358,12 +358,11 @@ is a singularity at \(\pt = \ecm\), due to a term
determinant. This singularity will vanish once considering a more
realistic process (see \cref{chap:pdf}).
The compatibility of histograms is tested as discussed in
\cref{sec:comphist} and the respective \(P\) and \(T\) values are
being included in the ratio plots. The histograms
\cref{fig:histeta,fig:histpt} are (see \cref{sec:comphist}) tested for
consistency with their \rivet-generated counterparts. They have a
\(P\)-value greater than \(.6\) and are therefore considered valid.
The compatibility of the histograms and their \rivet-generated
counterparts is tested as is discussed in \cref{sec:comphist} and the
respective \(P\) and \(T\) values are being included in the ratio
plots. The histograms have a \(P\)-value greater than \(0.6\) and are
therefore considered valid.
%%% Local Variables:
%%% mode: latex

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@ -7,11 +7,11 @@ scattering of hadrons to obtain experimentally verifiable
results. Hadrons are usually modeled as consisting of multiple
\emph{partons} (i.e. quarks and gluons) using Parton Density Functions
(PDFs). By using a leading order PDF, the cross section for the
process \(\ppgg\) on the matrix-element~\cite[14]{buckley:2011ge}
level\footnote{Neglecting the remnants and other processes like parton
showers, primordial transverse momentum and multiple interactions.}
and event samples of that process are obtained. These results are
being compared with results from \sherpa.
process \(\ppgg\) on the matrix-element level\footnote{Neglecting the
remnants and other processes like parton showers, primordial
transverse momentum and multiple interactions.} and event samples
of that process are obtained~\cite[14]{buckley:2011ge}. These results
are being compared with results from \sherpa.
%%% Local Variables:
%%% mode: latex

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@ -33,7 +33,7 @@
\clearpage
\thispagestyle{empty}
\null\vfill
{\large Eingreicht: \@date}
{\large Eingereicht: \@date}
\begin{tabular*}{.5\linewidth}[h]{ll}
1. Gutachter: & Dr. Frank Siegert \\