# Properties

 Label 1311.a.814131.1 Conductor 1311 Discriminant -814131 Sato-Tate group $\mathrm{USp}(4)$ $$\End(J_{\overline{\Q}}) \otimes \R$$ $$\R$$ $$\End(J_{\overline{\Q}}) \otimes \Q$$ $$\Q$$ $$\overline{\Q}$$-simple yes $$\mathrm{GL}_2$$-type no

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Show commands for: Magma / SageMath

## Minimal equation

magma: R<x> := PolynomialRing(Rationals()); C := HyperellipticCurve(R![0, 1, 4, 5, 5, 1], R![0, 1]);
sage: R.<x> = PolynomialRing(QQ); C = HyperellipticCurve(R([0, 1, 4, 5, 5, 1]), R([0, 1]))

$y^2 + xy = x^5 + 5x^4 + 5x^3 + 4x^2 + x$

## Invariants

 magma: Conductor(LSeries(C)); Factorization($1); $$N$$ = $$1311$$ = $$3 \cdot 19 \cdot 23$$ magma: Discriminant(C); Factorization(Integers()!$1); $$\Delta$$ = $$-814131$$ = $$-1 \cdot 3^{4} \cdot 19 \cdot 23^{2}$$

### G2 invariants

magma: G2Invariants(C);

 $$I_2$$ = $$-2400$$ = $$-1 \cdot 2^{5} \cdot 3 \cdot 5^{2}$$ $$I_4$$ = $$32640$$ = $$2^{7} \cdot 3 \cdot 5 \cdot 17$$ $$I_6$$ = $$-55062336$$ = $$-1 \cdot 2^{6} \cdot 3 \cdot 7 \cdot 53 \cdot 773$$ $$I_{10}$$ = $$-3334680576$$ = $$-1 \cdot 2^{12} \cdot 3^{4} \cdot 19 \cdot 23^{2}$$ $$J_2$$ = $$-300$$ = $$-1 \cdot 2^{2} \cdot 3 \cdot 5^{2}$$ $$J_4$$ = $$3410$$ = $$2 \cdot 5 \cdot 11 \cdot 31$$ $$J_6$$ = $$4761$$ = $$3^{2} \cdot 23^{2}$$ $$J_8$$ = $$-3264100$$ = $$-1 \cdot 2^{2} \cdot 5^{2} \cdot 7 \cdot 4663$$ $$J_{10}$$ = $$-814131$$ = $$-1 \cdot 3^{4} \cdot 19 \cdot 23^{2}$$ $$g_1$$ = $$30000000000/10051$$ $$g_2$$ = $$3410000000/30153$$ $$g_3$$ = $$-10000/19$$
Alternative geometric invariants: G2

## Automorphism group

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

## Rational points

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);

This curve is locally solvable everywhere.

magma: [C![-4,2,1],C![-1,-1,1],C![-1,2,1],C![0,0,1],C![1,0,0]];

All rational points: (-4 : 2 : 1), (-1 : -1 : 1), (-1 : 2 : 1), (0 : 0 : 1), (1 : 0 : 0)

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

Number of rational Weierstrass points: $$3$$

## Invariants of the Jacobian:

Analytic rank: $$0$$

magma: TwoSelmerGroup(Jacobian(C)); NumberOfGenerators($1); 2-Selmer rank: $$2$$ magma: HasSquareSha(Jacobian(C)); Order of Ш*: square Tamagawa numbers: 4 (p = 3), 1 (p = 19), 2 (p = 23) magma: TorsionSubgroup(Jacobian(SimplifiedModel(C))); AbelianInvariants($1);

Torsion: $$\Z/{2}\Z \times \Z/{8}\Z$$

### Sato-Tate group

 $$\mathrm{ST}$$ $$\simeq$$ $\mathrm{USp}(4)$ $$\mathrm{ST}^0$$ $$\simeq$$ $$\mathrm{USp}(4)$$

### Decomposition

Simple over $$\overline{\Q}$$

### Endomorphisms

Not of $$\GL_2$$-type over $$\Q$$

Endomorphism ring over $$\Q$$:
 $$\End (J_{})$$ $$\simeq$$ $$\Z$$ $$\End (J_{}) \otimes \Q$$ $$\simeq$$ $$\Q$$ $$\End (J_{}) \otimes \R$$ $$\simeq$$ $$\R$$

All $$\overline{\Q}$$-endomorphisms of the Jacobian are defined over $$\Q$$.