Properties

Label 28.4.d.a
Level $28$
Weight $4$
Character orbit 28.d
Analytic conductor $1.652$
Analytic rank $0$
Dimension $2$
CM discriminant -7
Inner twists $4$

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Newspace parameters

Copy content comment:Compute space of new eigenforms
 
Copy content gp:[N,k,chi] = [28,4,Mod(27,28)] mf = mfinit([N,k,chi],0) lf = mfeigenbasis(mf)
 
Copy content magma://Please install CHIMP (https://github.com/edgarcosta/CHIMP) if you want to run this code chi := DirichletCharacter("28.27"); S:= CuspForms(chi, 4); N := Newforms(S);
 
Copy content sage:from sage.modular.dirichlet import DirichletCharacter H = DirichletGroup(28, base_ring=CyclotomicField(2)) chi = DirichletCharacter(H, H._module([1, 1])) N = Newforms(chi, 4, names="a")
 
Level: \( N \) \(=\) \( 28 = 2^{2} \cdot 7 \)
Weight: \( k \) \(=\) \( 4 \)
Character orbit: \([\chi]\) \(=\) 28.d (of order \(2\), degree \(1\), minimal)

Newform invariants

Copy content comment:select newform
 
Copy content sage:traces = [2] f = next(g for g in N if [g.coefficient(i+1).trace() for i in range(1)] == traces)
 
Copy content gp:f = lf[1] \\ Warning: the index may be different
 
Self dual: no
Analytic conductor: \(1.65205348016\)
Analytic rank: \(0\)
Dimension: \(2\)
Coefficient field: \(\Q(\sqrt{-7}) \)
Copy content comment:defining polynomial
 
Copy content gp:f.mod \\ as an extension of the character field
 
Defining polynomial: \( x^{2} - x + 2 \) Copy content Toggle raw display
Coefficient ring: \(\Z[a_1, a_2]\)
Coefficient ring index: \( 1 \)
Twist minimal: yes
Sato-Tate group: $\mathrm{U}(1)[D_{2}]$

$q$-expansion

Copy content comment:q-expansion
 
Copy content sage:f.q_expansion() # note that sage often uses an isomorphic number field
 
Copy content gp:mfcoefs(f, 20)
 

Coefficients of the \(q\)-expansion are expressed in terms of \(\beta = \frac{1}{2}(1 + \sqrt{-7})\). We also show the integral \(q\)-expansion of the trace form.

\(f(q)\) \(=\) \( q + ( - \beta + 3) q^{2} + ( - 5 \beta + 7) q^{4} + (14 \beta - 7) q^{7} + ( - 17 \beta + 11) q^{8} - 27 q^{9} + (20 \beta - 10) q^{11} + (35 \beta + 7) q^{14} + ( - 45 \beta - 1) q^{16} + (27 \beta - 81) q^{18}+ \cdots + ( - 540 \beta + 270) q^{99}+O(q^{100}) \) Copy content Toggle raw display
\(\operatorname{Tr}(f)(q)\) \(=\) \( 2 q + 5 q^{2} + 9 q^{4} + 5 q^{8} - 54 q^{9} + 49 q^{14} - 47 q^{16} - 135 q^{18} + 70 q^{22} + 250 q^{25} + 245 q^{28} + 332 q^{29} - 275 q^{32} - 243 q^{36} - 900 q^{37} + 350 q^{44} - 574 q^{46} - 686 q^{49}+ \cdots - 1715 q^{98}+O(q^{100}) \) Copy content Toggle raw display

Character values

We give the values of \(\chi\) on generators for \(\left(\mathbb{Z}/28\mathbb{Z}\right)^\times\).

\(n\) \(15\) \(17\)
\(\chi(n)\) \(-1\) \(-1\)

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.

Copy content comment:embeddings in the coefficient field
 
Copy content gp:mfembed(f)
 
Label   \(\iota_m(\nu)\) \( a_{2} \) \( a_{3} \) \( a_{4} \) \( a_{5} \) \( a_{6} \) \( a_{7} \) \( a_{8} \) \( a_{9} \) \( a_{10} \)
27.1
0.500000 + 1.32288i
0.500000 1.32288i
2.50000 1.32288i 0 4.50000 6.61438i 0 0 18.5203i 2.50000 22.4889i −27.0000 0
27.2 2.50000 + 1.32288i 0 4.50000 + 6.61438i 0 0 18.5203i 2.50000 + 22.4889i −27.0000 0
\(n\): e.g. 2-40 or 990-1000
Significant digits:
Format:

Inner twists

Char Parity Ord Mult Type
1.a even 1 1 trivial
7.b odd 2 1 CM by \(\Q(\sqrt{-7}) \)
4.b odd 2 1 inner
28.d even 2 1 inner

Twists

       By twisting character orbit
Char Parity Ord Mult Type Twist Min Dim
1.a even 1 1 trivial 28.4.d.a 2
3.b odd 2 1 252.4.b.a 2
4.b odd 2 1 inner 28.4.d.a 2
7.b odd 2 1 CM 28.4.d.a 2
7.c even 3 2 196.4.f.a 4
7.d odd 6 2 196.4.f.a 4
8.b even 2 1 448.4.f.a 2
8.d odd 2 1 448.4.f.a 2
12.b even 2 1 252.4.b.a 2
21.c even 2 1 252.4.b.a 2
28.d even 2 1 inner 28.4.d.a 2
28.f even 6 2 196.4.f.a 4
28.g odd 6 2 196.4.f.a 4
56.e even 2 1 448.4.f.a 2
56.h odd 2 1 448.4.f.a 2
84.h odd 2 1 252.4.b.a 2
    
        By twisted newform orbit
Twist Min Dim Char Parity Ord Mult Type
28.4.d.a 2 1.a even 1 1 trivial
28.4.d.a 2 4.b odd 2 1 inner
28.4.d.a 2 7.b odd 2 1 CM
28.4.d.a 2 28.d even 2 1 inner
196.4.f.a 4 7.c even 3 2
196.4.f.a 4 7.d odd 6 2
196.4.f.a 4 28.f even 6 2
196.4.f.a 4 28.g odd 6 2
252.4.b.a 2 3.b odd 2 1
252.4.b.a 2 12.b even 2 1
252.4.b.a 2 21.c even 2 1
252.4.b.a 2 84.h odd 2 1
448.4.f.a 2 8.b even 2 1
448.4.f.a 2 8.d odd 2 1
448.4.f.a 2 56.e even 2 1
448.4.f.a 2 56.h odd 2 1

Hecke kernels

This newform subspace can be constructed as the kernel of the linear operator \( T_{3} \) acting on \(S_{4}^{\mathrm{new}}(28, [\chi])\). Copy content Toggle raw display

Hecke characteristic polynomials

$p$ $F_p(T)$
$2$ \( T^{2} - 5T + 8 \) Copy content Toggle raw display
$3$ \( T^{2} \) Copy content Toggle raw display
$5$ \( T^{2} \) Copy content Toggle raw display
$7$ \( T^{2} + 343 \) Copy content Toggle raw display
$11$ \( T^{2} + 700 \) Copy content Toggle raw display
$13$ \( T^{2} \) Copy content Toggle raw display
$17$ \( T^{2} \) Copy content Toggle raw display
$19$ \( T^{2} \) Copy content Toggle raw display
$23$ \( T^{2} + 47068 \) Copy content Toggle raw display
$29$ \( (T - 166)^{2} \) Copy content Toggle raw display
$31$ \( T^{2} \) Copy content Toggle raw display
$37$ \( (T + 450)^{2} \) Copy content Toggle raw display
$41$ \( T^{2} \) Copy content Toggle raw display
$43$ \( T^{2} + 285628 \) Copy content Toggle raw display
$47$ \( T^{2} \) Copy content Toggle raw display
$53$ \( (T - 590)^{2} \) Copy content Toggle raw display
$59$ \( T^{2} \) Copy content Toggle raw display
$61$ \( T^{2} \) Copy content Toggle raw display
$67$ \( T^{2} + 655452 \) Copy content Toggle raw display
$71$ \( T^{2} + 958300 \) Copy content Toggle raw display
$73$ \( T^{2} \) Copy content Toggle raw display
$79$ \( T^{2} + 56700 \) Copy content Toggle raw display
$83$ \( T^{2} \) Copy content Toggle raw display
$89$ \( T^{2} \) Copy content Toggle raw display
$97$ \( T^{2} \) Copy content Toggle raw display
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