How Do the Riemann Zeta and Dirichlet Eta Functions Interact?

arivero
Gold Member
Messages
3,481
Reaction score
187
Consider the separation of the Riemann Zeta function in two terms

\begin{flalign*}<br /> \zeta(s) &amp;= 1^{-s} + 2^{-s} + 3^{-s} + 4^{-s} + 5^{-s} + 6^{-s} + ... = &amp; \\<br /> &amp;=(1^{-s} + 3^{-s} + 5^{-s} + 7^{-s} + 9^{-s}+ ... ) + <br /> ( 2^{-s} + 4^{-s} + 6^{-s} + 8^{-s} + ...)&amp;=&amp; \\<br /> &amp;= (1 - 2^{-s}) \zeta(s) + 2^{-s} \zeta (s) &amp;=&amp; \zeta (s) &amp;<br /> \end{flalign*}

which is pretty tautological, and now the same play with the Dirichlet Eta function,

\begin{flalign*} <br /> \eta(s) &amp;= 1^{-s} - 2^{-s} + 3^{-s} - 4^{-s} + 5^{-s} - 6^{-s} + ... = \\<br /> &amp;=(1^{-s} + 3^{-s} + 5^{-s} + 7^{-s} + 9^{-s}+ ... ) <br /> - ( 2^{-s} + 4^{-s} + 6^{-s} + 8^{-s} + ...) &amp;=&amp; \\<br /> &amp;= (1 - 2^{-s}) \zeta(s) - 2^{-s} \zeta (s) &amp;=&amp; (1 - 2^{1-s}) \zeta (s) <br /> \end{flalign*}

The pair of functions J_\mp \equiv \frac 12 (\zeta(s) \pm \eta(s)) smells to susy quantum mechanics, doesn't it? Note how the pole (in s=1) of the Zeta function is canceled by substracting both functions, and that the difference between J_+ and J_- amounts to a zero in s=0.

Is this formalism used in number theory? Have the functions J\pm some specific name?
 
Last edited:
Physics news on Phys.org
Last edited:
We have for the Dirichlet Eta

eta(s) = (1 - 1/(2**(s - 1))*zeta(s)

(cf Derbyshire, Prime obsession, p 148)
 
RamaWolf said:
(cf Derbyshire, Prime obsession, p 148)

Also "Gamma", by Julian Havil. And I am a bit puzzled that the canonical text on the subject of Riemann Zeta Function, the one of H. M. Edwards, does not seem to find any use for this function.
 
##\textbf{Exercise 10}:## I came across the following solution online: Questions: 1. When the author states in "that ring (not sure if he is referring to ##R## or ##R/\mathfrak{p}##, but I am guessing the later) ##x_n x_{n+1}=0## for all odd $n$ and ##x_{n+1}## is invertible, so that ##x_n=0##" 2. How does ##x_nx_{n+1}=0## implies that ##x_{n+1}## is invertible and ##x_n=0##. I mean if the quotient ring ##R/\mathfrak{p}## is an integral domain, and ##x_{n+1}## is invertible then...
The following are taken from the two sources, 1) from this online page and the book An Introduction to Module Theory by: Ibrahim Assem, Flavio U. Coelho. In the Abelian Categories chapter in the module theory text on page 157, right after presenting IV.2.21 Definition, the authors states "Image and coimage may or may not exist, but if they do, then they are unique up to isomorphism (because so are kernels and cokernels). Also in the reference url page above, the authors present two...
When decomposing a representation ##\rho## of a finite group ##G## into irreducible representations, we can find the number of times the representation contains a particular irrep ##\rho_0## through the character inner product $$ \langle \chi, \chi_0\rangle = \frac{1}{|G|} \sum_{g\in G} \chi(g) \chi_0(g)^*$$ where ##\chi## and ##\chi_0## are the characters of ##\rho## and ##\rho_0##, respectively. Since all group elements in the same conjugacy class have the same characters, this may be...
Back
Top