Properties

Label 448.a.448.2
Conductor 448
Discriminant -448
Mordell-Weil group \(\Z/{12}\Z\)
Sato-Tate group $N(G_{1,3})$
\(\End(J_{\overline{\Q}}) \otimes \R\) \(\C \times \R\)
\(\End(J_{\overline{\Q}}) \otimes \Q\) \(\mathrm{CM} \times \Q\)
\(\overline{\Q}\)-simple no
\(\mathrm{GL}_2\)-type yes

Related objects

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Show commands for: Magma / SageMath

Minimal equation

Minimal equation

Simplified equation

$y^2 + (x^3 + x)y = -2x^4 + 7$ (homogenize, simplify)
$y^2 + (x^3 + xz^2)y = -2x^4z^2 + 7z^6$ (dehomogenize, simplify)
$y^2 = x^6 - 6x^4 + x^2 + 28$ (minimize, homogenize)

magma: R<x> := PolynomialRing(Rationals()); C := HyperellipticCurve(R![7, 0, 0, 0, -2], R![0, 1, 0, 1]);
 
sage: R.<x> = PolynomialRing(QQ); C = HyperellipticCurve(R([7, 0, 0, 0, -2]), R([0, 1, 0, 1]));
 
magma: X,pi:= SimplifiedModel(C);
 
sage: X = HyperellipticCurve(R([28, 0, 1, 0, -6, 0, 1]))
 

Invariants

Conductor: \( N \)  =  \(448\) = \( 2^{6} \cdot 7 \)
magma: Conductor(LSeries(C)); Factorization($1);
 
Discriminant: \( \Delta \)  =  \(-448\) = \( - 2^{6} \cdot 7 \)
magma: Discriminant(C); Factorization(Integers()!$1);
 

Igusa-Clebsch invariants

Igusa invariants

G2 invariants

\( I_2 \)  = \(-6624\) =  \( - 2^{5} \cdot 3^{2} \cdot 23 \)
\( I_4 \)  = \(1064640\) =  \( 2^{6} \cdot 3 \cdot 5 \cdot 1109 \)
\( I_6 \)  = \(-2717927424\) =  \( - 2^{11} \cdot 3^{2} \cdot 147457 \)
\( I_{10} \)  = \(-1835008\) =  \( - 2^{18} \cdot 7 \)
\( J_2 \)  = \(-828\) =  \( - 2^{2} \cdot 3^{2} \cdot 23 \)
\( J_4 \)  = \(17476\) =  \( 2^{2} \cdot 17 \cdot 257 \)
\( J_6 \)  = \(853888\) =  \( 2^{7} \cdot 7 \cdot 953 \)
\( J_8 \)  = \(-253107460\) =  \( - 2^{2} \cdot 5 \cdot 43 \cdot 294311 \)
\( J_{10} \)  = \(-448\) =  \( - 2^{6} \cdot 7 \)
\( g_1 \)  = \(6080953884912/7\)
\( g_2 \)  = \(155007628668/7\)
\( g_3 \)  = \(-1306723104\)

magma: IgusaClebschInvariants(C); IgusaInvariants(C); G2Invariants(C);
 
sage: C.igusa_clebsch_invariants(); [factor(a) for a in _]
 

Automorphism group

\(\mathrm{Aut}(X)\)\(\simeq\) $C_2^2$
magma: AutomorphismGroup(C); IdentifyGroup($1);
 
\(\mathrm{Aut}(X_{\overline{\Q}})\)\(\simeq\) $C_2^2$
magma: AutomorphismGroup(ChangeRing(C,AlgebraicClosure(Rationals()))); IdentifyGroup($1);
 

Rational points

All points: \((1 : 0 : 0),\, (1 : -1 : 0),\, (-2 : 5 : 1),\, (2 : -5 : 1)\)

magma: [C![-2,5,1],C![1,-1,0],C![1,0,0],C![2,-5,1]];
 

Number of rational Weierstrass points: \(2\)

magma: #Roots(HyperellipticPolynomials(SimplifiedModel(C)));
 

This curve is locally solvable everywhere.

magma: f,h:=HyperellipticPolynomials(C); g:=4*f+h^2; HasPointsEverywhereLocally(g,2) and (#Roots(ChangeRing(g,RealField())) gt 0 or LeadingCoefficient(g) gt 0);
 

Mordell-Weil group of the Jacobian:

Group structure: \(\Z/{12}\Z\)

magma: MordellWeilGroupGenus2(Jacobian(C));
 

Generator $D_0$ Height Order
\((2 : -5 : 1) - (1 : 0 : 0)\) \(z (x - 2z)\) \(=\) \(0,\) \(y\) \(=\) \(-x^3 + 3z^3\) \(0\) \(12\)

2-torsion field: 4.0.1568.1

BSD invariants

Hasse-Weil conjecture: verified
Analytic rank: \(0\)
Mordell-Weil rank: \(0\)
2-Selmer rank:\(1\)
Regulator: \( 1 \)
Real period: \( 31.17115 \)
Tamagawa product: \( 1 \)
Torsion order:\( 12 \)
Leading coefficient: \( 0.216466 \)
Analytic order of Ш: \( 1 \)   (rounded)
Order of Ш:square

Local invariants

Prime ord(\(N\)) ord(\(\Delta\)) Tamagawa L-factor
\(2\) \(6\) \(6\) \(1\) \(1 + T\)
\(7\) \(1\) \(1\) \(1\) \(( 1 - T )( 1 + 7 T^{2} )\)

Sato-Tate group

\(\mathrm{ST}\)\(\simeq\) $N(G_{1,3})$
\(\mathrm{ST}^0\)\(\simeq\) \(\mathrm{U}(1)\times\mathrm{SU}(2)\)

Decomposition of the Jacobian

Splits over \(\Q\)

Decomposes up to isogeny as the product of the non-isogenous elliptic curves:
  Elliptic curve 14.a4
  Elliptic curve 32.a2

Endomorphisms of the Jacobian

Of \(\GL_2\)-type over \(\Q\)

Endomorphism ring over \(\Q\):

\(\End (J_{})\)\(\simeq\)an order of index \(2\) in \(\Z \times \Z\)
\(\End (J_{}) \otimes \Q \)\(\simeq\)\(\Q\) \(\times\) \(\Q\)
\(\End (J_{}) \otimes \R\)\(\simeq\) \(\R \times \R\)

Smallest field over which all endomorphisms are defined:
Galois number field \(K = \Q (a) \simeq \) \(\Q(\sqrt{-1}) \) with defining polynomial \(x^{2} + 1\)

Not of \(\GL_2\)-type over \(\overline{\Q}\)

Endomorphism ring over \(\overline{\Q}\):

\(\End (J_{\overline{\Q}})\)\(\simeq\)an order of index \(8\) in \(\Z \times \Z [\sqrt{-1}]\)
\(\End (J_{\overline{\Q}}) \otimes \Q \)\(\simeq\)\(\Q\) \(\times\) \(\Q(\sqrt{-1}) \)
\(\End (J_{\overline{\Q}}) \otimes \R\)\(\simeq\) \(\R \times \C\)