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### 16.75 XCOLOR: Color factor in some fieldtheories

This package calculates the color factor in non-abelian gauge field theories using an algorithm due to Cvitanovich.

Documentation for this package is in plain text.

Author: A. Kryukov.

Program "xCOLOR" is intended for calculation the colour factor in non-abelian gauge field theories. It is realized Cvitanovich algorithm [1]. In comparision with "COLOR" program [2] it was made many improvements. The package was writen by symbolic mode. This version is faster then [2] more then 10 times.

After load the program by the following command load xcolor;
user can be able to use the next additional commands and operators.

#### Command SUdim.

Format: SUdim <any expression>;

Set the order of SU group.

The default value is 3, i.e. SU(3).

#### Command SpTT.

Format: SpTT <any expression>;

Set the normalization coefficient A: Sp(TiTj) = A*Delta(i,j). Default value is 1/2.

#### Operator QG.

Format: QG(inQuark,outQuark,Gluon)

Describe the quark-gluon vertex. Parameters may be any identifiers. First and second of then must be in- and out- quarks correspondently. Third one is a gluon.

#### Operator G3.

Format: G3(Gluon1,Gluon2,Gluon3)

Describe the three-gluon vertex. Parameters may be any identifiers. The order of gluons must be clock.

In terms of QG and G3 operators you input diagram in "color" space as a product of these operators. For example.

Diagram:                       REDUCE expression:

e1

---->---
/        \
|    e2    |
v1*..........*v2  <===>  QG(e3,e1,e2)*QG(e1,e3,e2)
|          |
\   e3   /
----<---

Here: --->--- quark

....... gluon

More detail see [2].

References.

[1] P.Cvitanovic, Phys. Rev. D14(1976), p.1536.

[2] A.Kryukov & A.Rodionov, Comp. Phys. Comm., 48(1988), pp.327-334.

Please send any remarks to my address above!

Good luck!

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