Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

A Modular Forms: Non-holomorphic Eisenstein Series E2 identity

  1. Nov 7, 2016 #1
    Hi,

    As part of showing that ##E^*_{2}(-1/t)=t^{2}E^*_{2}(t)##

    where ##E^*_{2}(t)= - \frac{3}{\pi Im (t) } + E_{2}(t) ##

    And since I have that ##t^{-2}E_{2}(-1/t)=E_{2}(t)+\frac{12}{2\pi i t} ##

    I conclude that I need to show that ##\frac{-1}{Im(-1/t)}+\frac{2t}{i} = \frac{-t^{2}}{Im(t)} ## [1]

    where ##t## inside the upper half plane
    Im=imaginary

    I also have the identification ##Im(\gamma.t)=\frac{Im(t)}{|ct+d | ^{2}}## [2],

    where ##\gamma## is inside ##SL_{2}(Z)##, the modular group of 2x2 matrices with integer numbers and determinant 1, (apologies I'm unsure how you do a matrix in latex), with components ##\gamma_{11}=a,\gamma_{12}=b, \gamma_{21}=c, \gamma_{22}=d ## .

    So this is part of a question where I am showing that ## E_{2}(t)^*## is weakly modular via showing that for the generators ##T## and ##S## the relevant identifications hold,##S## and ##T## inside ##SL_{2}(Z)##, so here, the one for ##S## being that :

    ##f(-1/t)=t^{k}f(t)##, ##S## is the matrix with components ##a=0,b=-1,c=1,d=0##

    Now I am looking at [2] and, using ##S## as ##\gamma## that
    ##Im(S.t)=\frac{Im(t)}{t^{2}}##, but we also know ##S.t=-1/t## and therefore I have ##Im(-1/t)=\frac{Im(t)}{t^{2}}##, and so I have no idea how I'm going to get a ##\frac{-2t}{i}## term in [1]

    Many thanks in advance.
     
  2. jcsd
  3. Nov 8, 2016 #2
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Modular Forms: Non-holomorphic Eisenstein Series E2 identity
  1. Eisenstein Series. (Replies: 3)

Loading...