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Dear Vladyslav,

I am doing the non-relativistic expansion (1/mN, mN is nucleon mass) of one-loop integral with the help of FeynCalc 9.2 and FeynHelpers (on Mathematica 10.4).

I found that the expanded result from PaXSeries is not the same as the result from Series, which is right for sure. I did something wrong when using PaXSeries or a possible bug?

In order to see the details, the code is given below,

(* Diagrams * )

ltdia = FCI[

SpinorUBarD[p, mN,

1].(GSD[k].(GSD[p] - GSD[k] - mN).GSD[k]).SpinorUD[p, mN,

1] FAD[{k, m\[Pi]}, {p - k, mN}]]

(* Do Integration *)

ltintOS =

1/(2 mN) Collect2[

TID[ltdia, k, UsePaVeBasis -> True, ToPaVe -> True,

PaVeAutoReduce -> True], Spinor] // DiracSimplify;

(* 1: Using the PaXSeires[mN, infinity, 0] in PaXEvaluate *)

IntHBPCB = (PaXEvaluate[

ltintOS /. {Pair[Momentum[p, D], Momentum[p, D]] -> mN^2},

PaXImplicitPrefactor -> 1/(2 \[Pi])^D, PaXAnalytic -> True,

PaXSeries -> {{mN, \[Infinity], 0}}] // Normal //

FCHideEpsilon) /. {SMP["Delta"] -> 0} // Simplify //

FullSimplify

(* 2: Using the Seires[mN, infinity, 0] after PaXEvaluate *)

IntHBPCB2 = (Series[

PaXEvaluate[

ltintOS /. {Pair[Momentum[p, D], Momentum[p, D]] -> mN^2},

PaXImplicitPrefactor -> 1/(2 \[Pi])^D, PaXAnalytic -> True] //

FCHideEpsilon, {mN, \[Infinity], 0}] //

Normal) /. {SMP["Delta"] -> 0} // Simplify

(* They are different. While, IntHBPCB2 is right.*)

IntHBPCB2 - IntHBPCB // Expand // FullSimplify

I am looking forward to your reply.

Thank you in advance.

Best regards,

Xiu-Lei

**Next message:**V. Shtabovenko: "Re: A possible bug: PaXSeries (FeynHelpers)"**Previous message:**V. Shtabovenko: "Re: Lagrangian of Randall-Sundrum Model"**Next in thread:**V. Shtabovenko: "Re: A possible bug: PaXSeries (FeynHelpers)"**Reply:**V. Shtabovenko: "Re: A possible bug: PaXSeries (FeynHelpers)"**Maybe reply:**X.-L. Ren: "Re: A possible bug: PaXSeries (FeynHelpers)"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ]**Mail actions:**[ respond to this message ] [ mail a new topic ]

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