error when running HyperTests.mpl

[Christoph Dlapa]

Hi,

I get the following error when running HyperTests.mpl from the command line:

################################################################################################################################
# Feynman Integrals
################################################################################################################################
> printf("Testing Feynman integrals\n"):
Testing Feynman integrals

> forgetAll():
> _hyper_splitting_field := {}:
> _hyper_algebraic_roots := true:

# Renormalized bubble-chain graphs
> bubbleRational := proc (n)
> local res, vars, S, p;
>   vars := {seq(x[i], i = 1 .. n)}:
>   # Assemble integrand
>   p := mul(x, `in`(x, vars)):
>   res := [[(-1)^(n+1)/p, []]]:
>   for S in combinat[powerset](vars) do
>       if S = {} or S = vars then next end if:
>       res := [op(res), eval([(-1)^nops(S)/(p*z), [[-1-z]]], z = add(x, `in`(x, `minus`(vars, S)))/add(x, `in`(x, S)))]:
>   end do:
>   # Integrate
>   newIntegration():
>   simplify(fibrationBasis(hyperInt(res, [seq(x[i], i = 2 .. n)]), [x[1]])):
> end proc:

> for n from 2 to 5 do 
>   Test(bubbleRational(n), n!/x[1], cat("Bubble chains with rational momentum flow, n=", n)): 
> end do:
Error, (in integrationStep) Divergence at x[2] = infinity of type x[2]
> quit

‌

Tested with maple2019 and maple2020 on two different machines.

Best regards,

Christoph

[Erik Panzer]

Dear Christoph,

‌

thank you for reporting!

Could you please check if the fix that I just submitted solves the problem?

It seems that Maple 2020 or already 2019 has introduced changes in the language that screwed up some of the tests.

‌

Best,

Erik

[Christoph Dlapa]

Dear Erik,

thank you for your quick response!

The tests now run through without an error. However, there is still one example in the Manual that I cannot run:

In “Two-loop box with diagonal, two different masses and two off-shell momenta”, when regularizing the integral, the line

F := factor(dimregPartial(F, {x[3], x[4], x[5]}, -varepsilon));
findDivergences(F, Kinematics);

fails to find a convergent representation.

‌

Now, since all tests pass, it is of course possible that I am doing something incorrectly.

Could you have a look if this example works without problems for you?

‌

Best,

Christoph

[Christoph Dlapa]

It seems that the issue comes from a mix of epsilon and varepsilon, which was probably also introduced or changed in one of the new maple versions.

Being consistent in the used variant of epsilon resolves the problem.

Thanks for your help! The thread can be closed.

Best,

Christoph

[Erik Panzer]

Thank you Christoph for reporting and investigating this!

Indeed the manual worksheet has not been overhauled ever and could do with some updates. I am however reluctant to change it, from fear that editing it with my current version might make it unreadable for earlier Maple versions. I’ll pin it as a separate issue.

Please keep reporting if you find any other problems!

With best wishes,

Erik