Newspace parameters
comment: Compute space of new eigenforms
[N,k,chi] = [20,5,Mod(19,20)]
mf = mfinit([N,k,chi],0)
lf = mfeigenbasis(mf)
from sage.modular.dirichlet import DirichletCharacter
H = DirichletGroup(20, base_ring=CyclotomicField(2))
chi = DirichletCharacter(H, H._module([1, 1]))
N = Newforms(chi, 5, names="a")
//Please install CHIMP (https://github.com/edgarcosta/CHIMP) if you want to run this code
chi := DirichletCharacter("20.19");
S:= CuspForms(chi, 5);
N := Newforms(S);
| Level: | \( N \) | \(=\) | \( 20 = 2^{2} \cdot 5 \) |
| Weight: | \( k \) | \(=\) | \( 5 \) |
| Character orbit: | \([\chi]\) | \(=\) | 20.d (of order \(2\), degree \(1\), 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: | yes |
| Analytic conductor: | \(2.06739926168\) |
| Analytic rank: | \(0\) |
| Dimension: | \(1\) |
| Coefficient field: | \(\mathbb{Q}\) |
| Coefficient ring: | \(\mathbb{Z}\) |
| Coefficient ring index: | \( 1 \) |
| Twist minimal: | yes |
| Sato-Tate group: | $\mathrm{U}(1)[D_{2}]$ |
$q$-expansion
comment: q-expansion
sage: f.q_expansion() # note that sage often uses an isomorphic number field
gp: mfcoefs(f, 20)
Character values
We give the values of \(\chi\) on generators for \(\left(\mathbb{Z}/20\mathbb{Z}\right)^\times\).
| \(n\) | \(11\) | \(17\) |
| \(\chi(n)\) | \(-1\) | \(-1\) |
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 | \(\iota_m(\nu)\) | \( a_{2} \) | \( a_{3} \) | \( a_{4} \) | \( a_{5} \) | \( a_{6} \) | \( a_{7} \) | \( a_{8} \) | \( a_{9} \) | \( a_{10} \) | |||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 19.1 |
|
4.00000 | −2.00000 | 16.0000 | 25.0000 | −8.00000 | −82.0000 | 64.0000 | −77.0000 | 100.000 | |||||||||||||||||||||
Inner twists
| Char | Parity | Ord | Mult | Type |
|---|---|---|---|---|
| 1.a | even | 1 | 1 | trivial |
| 20.d | odd | 2 | 1 | CM by \(\Q(\sqrt{-5}) \) |
Twists
| By twisting character orbit | |||||||
|---|---|---|---|---|---|---|---|
| Char | Parity | Ord | Mult | Type | Twist | Min | Dim |
| 1.a | even | 1 | 1 | trivial | 20.5.d.b | yes | 1 |
| 3.b | odd | 2 | 1 | 180.5.f.a | 1 | ||
| 4.b | odd | 2 | 1 | 20.5.d.a | ✓ | 1 | |
| 5.b | even | 2 | 1 | 20.5.d.a | ✓ | 1 | |
| 5.c | odd | 4 | 2 | 100.5.b.b | 2 | ||
| 8.b | even | 2 | 1 | 320.5.h.b | 1 | ||
| 8.d | odd | 2 | 1 | 320.5.h.a | 1 | ||
| 12.b | even | 2 | 1 | 180.5.f.b | 1 | ||
| 15.d | odd | 2 | 1 | 180.5.f.b | 1 | ||
| 20.d | odd | 2 | 1 | CM | 20.5.d.b | yes | 1 |
| 20.e | even | 4 | 2 | 100.5.b.b | 2 | ||
| 40.e | odd | 2 | 1 | 320.5.h.b | 1 | ||
| 40.f | even | 2 | 1 | 320.5.h.a | 1 | ||
| 60.h | even | 2 | 1 | 180.5.f.a | 1 | ||
| By twisted newform orbit | |||||||
|---|---|---|---|---|---|---|---|
| Twist | Min | Dim | Char | Parity | Ord | Mult | Type |
| 20.5.d.a | ✓ | 1 | 4.b | odd | 2 | 1 | |
| 20.5.d.a | ✓ | 1 | 5.b | even | 2 | 1 | |
| 20.5.d.b | yes | 1 | 1.a | even | 1 | 1 | trivial |
| 20.5.d.b | yes | 1 | 20.d | odd | 2 | 1 | CM |
| 100.5.b.b | 2 | 5.c | odd | 4 | 2 | ||
| 100.5.b.b | 2 | 20.e | even | 4 | 2 | ||
| 180.5.f.a | 1 | 3.b | odd | 2 | 1 | ||
| 180.5.f.a | 1 | 60.h | even | 2 | 1 | ||
| 180.5.f.b | 1 | 12.b | even | 2 | 1 | ||
| 180.5.f.b | 1 | 15.d | odd | 2 | 1 | ||
| 320.5.h.a | 1 | 8.d | odd | 2 | 1 | ||
| 320.5.h.a | 1 | 40.f | even | 2 | 1 | ||
| 320.5.h.b | 1 | 8.b | even | 2 | 1 | ||
| 320.5.h.b | 1 | 40.e | odd | 2 | 1 | ||
Hecke kernels
This newform subspace can be constructed as the kernel of the linear operator
\( T_{3} + 2 \)
acting on \(S_{5}^{\mathrm{new}}(20, [\chi])\).
Hecke characteristic polynomials
| $p$ | $F_p(T)$ |
|---|---|
| $2$ |
\( T - 4 \)
|
| $3$ |
\( T + 2 \)
|
| $5$ |
\( T - 25 \)
|
| $7$ |
\( T + 82 \)
|
| $11$ |
\( T \)
|
| $13$ |
\( T \)
|
| $17$ |
\( T \)
|
| $19$ |
\( T \)
|
| $23$ |
\( T - 878 \)
|
| $29$ |
\( T + 1198 \)
|
| $31$ |
\( T \)
|
| $37$ |
\( T \)
|
| $41$ |
\( T - 482 \)
|
| $43$ |
\( T - 2078 \)
|
| $47$ |
\( T + 4402 \)
|
| $53$ |
\( T \)
|
| $59$ |
\( T \)
|
| $61$ |
\( T + 4078 \)
|
| $67$ |
\( T - 4478 \)
|
| $71$ |
\( T \)
|
| $73$ |
\( T \)
|
| $79$ |
\( T \)
|
| $83$ |
\( T + 8002 \)
|
| $89$ |
\( T - 4322 \)
|
| $97$ |
\( T \)
|
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