reduce-historical/r38/packages/hephys/physop.rlg

Tue Feb 10 12:26:52 2004 run on Linux
COMMENT
        test file for the PHYSOP package;

% load_package physop;  % Load a compiled version of the physop package.
% showtime;
linelength(72)$


% Example 1: Quantum Mechanics of a Dirac particle in an external
%                      electromagnetic field
VECOP P,A,K;


SCALOP M;


NONCOM P,A;


PHYSINDEX J,L;


oporder M,K,A,P;



% we have to set off allfac here since otherwise there appear
% spurious negative powers in the printed output
 off allfac;


FOR ALL J,L LET COMM(P(J),A(L))=K(J)*A(L);


H:= COMMUTE(P**2/(2*M),E/(4*M**2)*(P DOT A));


            -1    -1    -1
h := (2*e*(m  )*(m  )*(m  )*k(idx1)*a(idx2)*p(idx1)*p(idx2)

             -1    -1    -1
       + e*(m  )*(m  )*(m  )*k(idx1)*k(idx1)*a(idx2)*p(idx2)

             -1    -1    -1
       + e*(m  )*(m  )*(m  )*k(idx1)*k(idx1)*k(idx2)*a(idx2)

               -1    -1    -1
       + 2*e*(m  )*(m  )*(m  )*k(idx1)*k(idx2)*a(idx2)*p(idx1))/8

% showtime;
%assign the corresponding value to the adjoint of H
H!+ := adj H;


  +                +          +          +          +      -1      -1
(h ) := (e*(a(idx2) )*(k(idx1) )*(k(idx1) )*(k(idx2) )*(m!+  )*(m!+  )

              -1                +          +          +          +
         *(m!+  ) + 2*e*(p(idx1) )*(a(idx2) )*(k(idx1) )*(k(idx2) )

              -1      -1      -1                +          +          +
         *(m!+  )*(m!+  )*(m!+  ) + 2*e*(p(idx1) )*(p(idx2) )*(a(idx2) )

                  +      -1      -1      -1              +          +
         *(k(idx1) )*(m!+  )*(m!+  )*(m!+  ) + e*(p(idx2) )*(a(idx2) )

                  +          +      -1      -1      -1
         *(k(idx1) )*(k(idx1) )*(m!+  )*(m!+  )*(m!+  ))/8

% showtime;
% note the ordering of operators in the result!
% enhance the readability of the output
 on allfac;


ON CONTRACT;


H;


       3
(e*m!-1

                                            2            2
 *(2*a dot p*k dot p + 2*k dot a*k dot p + k *a dot p + k *k dot a))/8

% showtime;
% Example 2: Virasoro Algebra from Conformal Field Theory


operator  del;

  % this is just a definition of a delta function
for all n such that numberp n let del(n) =
     if n=0 then 1
     else 0;



scalop l;


noncom l,l;


state bra,ket;


% commutation relation of the operator l;
for all n,m let comm(l(n),l(m)) =
      (m-n)*l(n+m)+c/12*(m**3-m)*del(n+m)*unit;

 %modified 1.1

for all n let l!+(n) = l(-n);




% relation for the states
for all h let bra!+(h) = ket(h);


for all p,q let bra(q) | ket(p) = del(p-q);



for all r,h such that r < 0 or (r <2 and h=0) let
             l(r) | ket(h) = 0;



for all r,h such that r > 0 or (r  > -2 and h = 0) let
             bra(h) | l(r) = 0;



% define a procedure to calculate V.E.V.
procedure Vak(X);
bra(0) | X | ket(0);


vak


% and now some calculations;
MA:= adj(l(3)*l(5))*l(3)*l(5);


ma := 2*l(8)*l(-3)*l(-5) + 4*l(8)*l(-8) + l(5)*l(3)*l(-3)*l(-5)

       + 2*l(5)*l(3)*l(-8) + 6*l(5)*l(0)*l(-5) + 8*l(5)*l(-2)*l(-3)

       + 60*l(5)*l(-5) + 8*l(3)*l(2)*l(-5) + 10*l(3)*l(0)*l(-3)

                                                 2
       + 112*l(3)*l(-3) + 64*l(2)*l(-2) + 60*l(0)  + 556*l(0)

             2
       + 20*c *unit + 2*c*l(5)*l(-5) + 10*c*l(3)*l(-3) + 80*c*l(0)

       + 332*c*unit
  %modified 1.1
% showtime;

% here is the VEV of m
vak(Ma);


4*c*(5*c + 83)

% showtime;
% and now calculate another matrix element

matel := bra(1) | ma  | ket(1);

        *************** WARNING: ***************
Evaluation incomplete due to missing elementary relations

matel := bra(1) | (l(0) | 556*ket(1)) + bra(1) | (l(0) | 80*c*ket(1))

                                                   2
          + bra(1) | (l(0)*l(0) | 60*ket(1)) + 20*c  + 332*c
  %modified 1.1
% showtime;
% this evaluation is incomplete so supply the missing relation
for all h let l(0) | ket(h) = h*ket(h);


% and reevaluate matel
matel := matel;


               2
matel := 4*(5*c  + 103*c + 154)

% showtime;


% Example 4: some manipulations with gamma matrices to demonstrate
%            the use of commutators and anticommutators


off allfac;


vecop gamma,q;


tensop sigma(2);


antisymmetric sigma;


noncom gamma,gamma;


noncom sigma,gamma;


physindex mu,nu;


operator delta;


for all mu,nu let anticomm(gamma(mu),gamma(nu))=2*delta(mu,nu)*unit,
                  comm(gamma(mu),gamma(nu))=2*I*sigma(mu,nu);



oporder p,q,gamma,sigma;


off allfac;


on anticom;


(gamma dot p)*(gamma dot q);


p(idx4)*q(idx5)*gamma(idx4)*gamma(idx5)

% showtime;

off anticom;


(gamma dot p)*(gamma dot q);


p(idx6)*q(idx7)*gamma(idx6)*gamma(idx7)

% showtime;

commute((gamma dot p),(gamma dot q));


2*i*p(idx8)*q(idx9)*sigma(idx8,idx9)

% showtime;
anticommute((gamma dot p),(gamma dot q));


2*p(idx10)*q(idx11)*gamma(idx10)*gamma(idx11)

 - 2*i*p(idx10)*q(idx11)*sigma(idx10,idx11)

on anticom;


anticommute((gamma dot p),(gamma dot q));


2*delta(idx13,idx12)*p(idx12)*q(idx13)

% showtime;

end;


Time for test: 30 ms