VECTOR _ _ _ _ _ _ _ _ _ _ _ _ declaration
The vector declaration declares that its arguments are of type vect or.
vector<identifier>{,<identifier>}*
<identifier> must be a valid REDUCE identifier. It may have already been used for a matrix, array, operator or scalar variable. After an identifier has been declared to be a vector, it may not be used as a scalar variable.
Vectors are special entities for high-energy physics calculations. You cannot put values into their coordinates; they do not have coordinates. They are legal arguments for the high-energy physics operators eps, g and . (dot). Vector variables are used to represent gamma matrices and gamma matrices contracted with Lorentz 4-vectors, since there are no Dirac variables per se in the system. Vectors do follow the usual vector rules for arithmetic operations: + and - operate upon two or more vectors, producing a vector; * and / cannot be used between vectors; the scalar product is represented by the . operator; and the product of a scalar and vector expression is well defined, and is a vector.
You can represent components of vectors by including representations of unit vectors in your system. For instance, letting E0 represent the unit vector (1,0,0,0), the command
V1.E0 := 0;would set up the substitution of zero for the first componen t of the vector V1.
Identifiers that are declared by the index and mass declaratio ns are automatically declared to be vectors.
The following errors can occur in calculations using the high energy physics package:
A represents only gamma5 in vector expressionsYou have tried to use A i n some way other than gamma5 in a high-energy physics expression.
Gamma5 not allowed unless vecdim is 4You have used gamma_5 in a high-en ergy physics computation involving a vector dimension other than 4.
<ID> has no mass
One of the arguments to mshell has had no mass assigned to it, in high-energy physics calculations.
Missing arguments for G operatorA line symbol is missing in a gamma mat rix expression in high-energy physics calculations.
Unmatched index<list>
The parser has found unmatched indices during the evaluation of a gamma matrix expression in high-energy physics calculations.