sum in the same line as a fraction

Question

I'm sorry if this has been asked. I'm new to this and to Latex. I have this piece of code:

\[
  e^{-\xi_1 Y_1^N} = \exp\left(-\frac{\xi_1}{N}\ \sum_{n\geq1}{}V_n^1
  e^{-s_n}\1_{\{ s_n \leq T_1\}}\right)
\]

And when compiling the line of fraction gets placed at the height of the middle of the sigma symbol of the \sum. I would like to place it at the height of the Base of the sigma symbol.

Thank you in advance!

Answer 1

The first equation below features the frational term shifted down so that the fraction bar is at the same height as the lower horizontal stroke of the summation symbol. The second equation features a more standard look.

Speaking for myself, I'd go with the look of the second equation.

\documentclass{article}
\usepackage{amsmath,amsfonts}
\DeclareMathOperator{\1}{\mathbf{1}} % educated guess...
\newcommand\e{\mathrm{e}}
\begin{document}

fractional term shifted down:
\[ 
\e^{-\xi_1^{} Y_1^N} 
= \exp\biggl(- \lower1.6ex\hbox{$\dfrac{\xi_1}{N}$} 
     \sum_{n\geq1}{}V_n^1 
     \e^{-s_n} \1_{\{ s_n \leq T_1\}}\biggr) 
\]

\bigskip
normal look:
\[ 
\e^{-\xi_1^{} Y_1^N} 
= \exp\biggl(- \frac{\xi_1}{N} 
     \sum_{n\geq1}{}V_n^1 
     \e^{-s_n} \1_{\{ s_n \leq T_1\}}\biggr) 
\]

\end{document}

---

Addendum: Judging by the comment the OP left, it may be that the following look -- placing the limit of the summation to the side rather than below the summation symbol -- is really what is supposed to be achieved.

\documentclass{article}
\usepackage{amsmath}
\DeclareMathOperator{\1}{\mathbf{1}} 
\newcommand\e{\mathrm{e}}
\begin{document}
\[ 
\e^{-\xi_1^{} Y_1^N} 
= \exp\Bigl(- \frac{\xi_1}{N} 
     \sum\nolimits_{n\geq1}V_n^1 
     \e^{-s_n} \1_{\{ s_n \leq T_1\}}\Bigr) 
\]
\end{document}