TITLE: A stupid question on automorphic l-function
QUESTION [7 upvotes]: This may be a silly question for experts in this area. But I am really suffering for not being able to compute local-L function of some automorphic representation.
So, I post it hoping some benevolent one shed me a light.
Let $\pi$ be a local component of some global irr.cusp.unitary automorphic representation of $U(2)$ at split finite place.(i.e. $\pi$ is $GL(2)$ reps)
Then, there are three possible candidates for $\pi$ except for supercuspidal;
1)$B(\chi_{1} , \chi_{2})$ for $\chi_{1} \cdot \chi_{2}^{-1}=1$
2)$B(\chi_{1} , \chi_{2})$ for $\chi_{1} \cdot \chi_{2}^{-1} \ne 1$
3)irreducible quotient of $B(\chi\left\vert \cdot \right\vert^{\frac{1}{2}},\chi\left\vert \cdot \right\vert^{-\frac{1}{2}})$ for unitary character $\chi$.
(here, all $\chi, \chi_{1} , \chi_{2}$ are character of $GL(1)$ )
Then, for any character $\gamma$ of $GL(1)$, 
what is $L(s,\pi \otimes \gamma)$ for the above three each $\pi$?
(here, L-function is local L-function and we consider $\gamma$ as $GL(2)$ character through determinant map)
Since my main concern lies in computing the order of zero or pole of the above $L$-function at $s=0$, if it is hard to write explicitly in ramified case, would you just inform me the result for each cases? Then, I am very grateful for your kindness.
(For beginner in this area, getting used to L-function calculation is quite difficult.)

REPLY [4 votes]: Since I was just asking a similar case, I can give you a partial answer. In 
http://www.math.ou.edu/~kmartin/autreps/ch3.pdf   in Definition 3.1.16
you can find the $p$-adic result, which generalize to the non-archimedean, zero-characterictic cases in the obviuous manner. References are Bump or Goldfeld-Hundley.
For the tensoring by $\gamma \circ \det$ (I think that's what you are asking about), note that
$$ \gamma \circ \det \otimes B(\chi_1, \chi_2) = B(\chi_1\gamma, \chi_2 \gamma),$$
and for the Steinberg/special rep $St(\chi) \otimes \gamma \circ \det = St(\chi\gamma)$ as well. The $L$-function of a supercuspidal representation is a constant (usually chosen to be one).
The computation at the real places can be found as Lemma 5.15.1, and the complex case on page 118 ff. in Jacquet-Langlands (both with computation).