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Let $G$ be a finite group of even order which has only one non-principal irreducible character $\chi$ of degree $d$, $d\in \mathbb{N}$, with the following property (we name it $(*_d)$):

$(*_d)$: There exist $x,y\in G$ such that $o(x)=o(y)=2$ and $\chi(x)\neq \chi(y)$.

I know that $A_n$ ($n\geq 8$) has the property $(*_{n-1})$ and $S_n$ ($n\geq 4$) has the property $(*_1)$.

Now, for a suitable $d\in \mathbb{N}$, I have a question:

Is there any other solvable example of groups $G$ with the property $(*_d)$?

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    $\begingroup$ Any group with a unique normal subgroup $N$ of index 2, such that $|N|$ is even and there exist elements of order 2 outside of $N$ will have $(*_1)$. There are many such solvable examples. $\endgroup$
    – Derek Holt
    Nov 26, 2013 at 21:36
  • $\begingroup$ @DerekHolt. Thanks. Is there any alternative answer to this question? $\endgroup$ Nov 27, 2013 at 9:08
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    $\begingroup$ You should do a computer search with GAP. For example $S_4$ has $(*_2)$ and there are seven groups of order 32 with $(*_4)$. $\endgroup$
    – Derek Holt
    Nov 27, 2013 at 9:52
  • $\begingroup$ Would you please give an answer based on mathematical facts, other than the examples given by the computer software (GAP)? $\endgroup$ Nov 29, 2013 at 18:39
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    $\begingroup$ I have been unsuccessful in trying to find a solvable group G and an ODD integer d such that G has a unique irreducible character chi of degree d, and in addition, chi is not constant on the set of involutions. I wonder if this can happen. I have found examples where there is more than one class of involutions, but chi always seems to have the same value on all of the involutions. $\endgroup$ Dec 4, 2013 at 19:24

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I have found an example of a solvable group that has exactly one irreducible character of degree $27$, and that character takes on two different values on involutions. The group, which has order $2^6 3^3$, can be constructed as a semidirect product of an elementary abelian $2$-group $V$ of order $2^6$ acted on by a nonabelian $3$-group $T$ with order $3^3$ and exponent $3$.

To construct the group, observe that $T$ has an irreducible module $V$ of dimension $3$ over the field of order $4$. View $V$ as an elementary abelian $2$-group and construct the semidirect product. I checked that this works by building the group using the Magma software, and then asking Magma for the character table.

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