Newspace parameters
comment: Compute space of new eigenforms
[N,k,chi] = [381,2,Mod(20,381)]
mf = mfinit([N,k,chi],0)
lf = mfeigenbasis(mf)
from sage.modular.dirichlet import DirichletCharacter
H = DirichletGroup(381, base_ring=CyclotomicField(6))
chi = DirichletCharacter(H, H._module([3, 5]))
N = Newforms(chi, 2, names="a")
//Please install CHIMP (https://github.com/edgarcosta/CHIMP) if you want to run this code
chi := DirichletCharacter("381.20");
S:= CuspForms(chi, 2);
N := Newforms(S);
| Level: | \( N \) | \(=\) | \( 381 = 3 \cdot 127 \) |
| Weight: | \( k \) | \(=\) | \( 2 \) |
| Character orbit: | \([\chi]\) | \(=\) | 381.g (of order \(6\), degree \(2\), minimal) |
Newform invariants
comment: select newform
sage: f = N[0] # Warning: the index may be different
gp: f = lf[1] \\ Warning: the index may be different
| Self dual: | no |
| Analytic conductor: | \(3.04230031701\) |
| Analytic rank: | \(0\) |
| Dimension: | \(4\) |
| Relative dimension: | \(2\) over \(\Q(\zeta_{6})\) |
| Coefficient field: | \(\Q(\sqrt{-3}, \sqrt{-11})\) |
|
comment: defining polynomial
gp: f.mod \\ as an extension of the character field
|
|
| Defining polynomial: |
\( x^{4} - x^{3} - 2x^{2} - 3x + 9 \)
|
| Coefficient ring: | \(\Z[a_1, \ldots, a_{7}]\) |
| Coefficient ring index: | \( 1 \) |
| Twist minimal: | yes |
| Sato-Tate group: | $\mathrm{SU}(2)[C_{6}]$ |
$q$-expansion
comment: q-expansion
sage: f.q_expansion() # note that sage often uses an isomorphic number field
gp: mfcoefs(f, 20)
Coefficients of the \(q\)-expansion are expressed in terms of a basis \(1,\beta_1,\beta_2,\beta_3\) for the coefficient ring described below. We also show the integral \(q\)-expansion of the trace form.
Basis of coefficient ring in terms of a root \(\nu\) of
\( x^{4} - x^{3} - 2x^{2} - 3x + 9 \)
:
| \(\beta_{1}\) | \(=\) |
\( \nu \)
|
| \(\beta_{2}\) | \(=\) |
\( ( \nu^{3} + 2\nu^{2} - 2\nu - 3 ) / 6 \)
|
| \(\beta_{3}\) | \(=\) |
\( ( -\nu^{3} + 2\nu + 3 ) / 2 \)
|
| \(\nu\) | \(=\) |
\( \beta_1 \)
|
| \(\nu^{2}\) | \(=\) |
\( \beta_{3} + 3\beta_{2} \)
|
| \(\nu^{3}\) | \(=\) |
\( -2\beta_{3} + 2\beta _1 + 3 \)
|
Character values
We give the values of \(\chi\) on generators for \(\left(\mathbb{Z}/381\mathbb{Z}\right)^\times\).
| \(n\) | \(128\) | \(130\) |
| \(\chi(n)\) | \(-1\) | \(1 - \beta_{2}\) |
Embeddings
For each embedding \(\iota_m\) of the coefficient field, the values \(\iota_m(a_n)\) are shown below.
For more information on an embedded modular form you can click on its label.
comment: embeddings in the coefficient field
gp: mfembed(f)
| Label | \(\iota_m(\nu)\) | \( a_{2} \) | \( a_{3} \) | \( a_{4} \) | \( a_{5} \) | \( a_{6} \) | \( a_{7} \) | \( a_{8} \) | \( a_{9} \) | \( a_{10} \) | ||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 20.1 |
|
1.73205i | −0.500000 | − | 1.65831i | −1.00000 | −2.00000 | 2.87228 | − | 0.866025i | 0.686141 | − | 0.396143i | 1.73205i | −2.50000 | + | 1.65831i | − | 3.46410i | |||||||||||||||||||||
| 20.2 | 1.73205i | −0.500000 | + | 1.65831i | −1.00000 | −2.00000 | −2.87228 | − | 0.866025i | −2.18614 | + | 1.26217i | 1.73205i | −2.50000 | − | 1.65831i | − | 3.46410i | ||||||||||||||||||||||
| 362.1 | − | 1.73205i | −0.500000 | − | 1.65831i | −1.00000 | −2.00000 | −2.87228 | + | 0.866025i | −2.18614 | − | 1.26217i | − | 1.73205i | −2.50000 | + | 1.65831i | 3.46410i | |||||||||||||||||||||
| 362.2 | − | 1.73205i | −0.500000 | + | 1.65831i | −1.00000 | −2.00000 | 2.87228 | + | 0.866025i | 0.686141 | + | 0.396143i | − | 1.73205i | −2.50000 | − | 1.65831i | 3.46410i | |||||||||||||||||||||
Inner twists
| Char | Parity | Ord | Mult | Type |
|---|---|---|---|---|
| 1.a | even | 1 | 1 | trivial |
| 381.g | even | 6 | 1 | inner |
Twists
| By twisting character orbit | |||||||
|---|---|---|---|---|---|---|---|
| Char | Parity | Ord | Mult | Type | Twist | Min | Dim |
| 1.a | even | 1 | 1 | trivial | 381.2.g.a | ✓ | 4 |
| 3.b | odd | 2 | 1 | 381.2.g.b | yes | 4 | |
| 127.d | odd | 6 | 1 | 381.2.g.b | yes | 4 | |
| 381.g | even | 6 | 1 | inner | 381.2.g.a | ✓ | 4 |
| By twisted newform orbit | |||||||
|---|---|---|---|---|---|---|---|
| Twist | Min | Dim | Char | Parity | Ord | Mult | Type |
| 381.2.g.a | ✓ | 4 | 1.a | even | 1 | 1 | trivial |
| 381.2.g.a | ✓ | 4 | 381.g | even | 6 | 1 | inner |
| 381.2.g.b | yes | 4 | 3.b | odd | 2 | 1 | |
| 381.2.g.b | yes | 4 | 127.d | odd | 6 | 1 | |
Hecke kernels
This newform subspace can be constructed as the intersection of the kernels of the following linear operators acting on \(S_{2}^{\mathrm{new}}(381, [\chi])\):
|
\( T_{2}^{2} + 3 \)
|
|
\( T_{5} + 2 \)
|
Hecke characteristic polynomials
| $p$ | $F_p(T)$ |
|---|---|
| $2$ |
\( (T^{2} + 3)^{2} \)
|
| $3$ |
\( (T^{2} + T + 3)^{2} \)
|
| $5$ |
\( (T + 2)^{4} \)
|
| $7$ |
\( T^{4} + 3 T^{3} + \cdots + 4 \)
|
| $11$ |
\( T^{4} - 15 T^{3} + \cdots + 256 \)
|
| $13$ |
\( T^{4} + 33T^{2} + 1089 \)
|
| $17$ |
\( T^{4} - 9 T^{3} + \cdots + 16 \)
|
| $19$ |
\( (T^{2} - 7 T + 4)^{2} \)
|
| $23$ |
\( T^{4} + 3 T^{3} + \cdots + 36 \)
|
| $29$ |
\( T^{4} + 11 T^{3} + \cdots + 484 \)
|
| $31$ |
\( T^{4} - 4 T^{3} + \cdots + 841 \)
|
| $37$ |
\( (T^{2} - T + 1)^{2} \)
|
| $41$ |
\( T^{4} - 3 T^{3} + \cdots + 4 \)
|
| $43$ |
\( T^{4} + 21 T^{3} + \cdots + 1156 \)
|
| $47$ |
\( T^{4} + 28T^{2} + 64 \)
|
| $53$ |
\( T^{4} + 5 T^{3} + \cdots + 4624 \)
|
| $59$ |
\( T^{4} - 3 T^{3} + \cdots + 36 \)
|
| $61$ |
\( (T^{2} + 9 T - 54)^{2} \)
|
| $67$ |
\( T^{4} - 18 T^{3} + \cdots + 289 \)
|
| $71$ |
\( T^{4} + 3 T^{3} + \cdots + 4624 \)
|
| $73$ |
\( (T^{2} - 5 T - 2)^{2} \)
|
| $79$ |
\( (T^{2} - 13 T + 169)^{2} \)
|
| $83$ |
\( T^{4} + 21 T^{3} + \cdots + 10404 \)
|
| $89$ |
\( (T - 2)^{4} \)
|
| $97$ |
\( T^{4} - 39 T^{3} + \cdots + 15376 \)
|
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