Support Routines

A collection of small functions are available. Most of the routines come in two versions, one that takes a vector and one that takes an array of vectors and an index as arguments.

• vcopy (A,I,B,J) copies the i'th vector of array A to the j'th vector of array B.
• vadd(A,I,B,J,IRECOM) adds the j'th vector in array B to the i'th vector in array A. The available recombination schemes are :

  IRECOM=1

  E/JADE : $\bf p$ : = $\bf p_a$ + $\bf p_b.$

  IRECOM=2

  E0 : E : = E_a + E_b,$\vec{p}\,$ : = ${\vert\vec p\vert\over E}$($\vec{p}_{a}^{}$ + $\vec{p}_{b}^{}$) (momentum rescaling)

  IRECOM=3

  P : $\vec{p}\,$ : = ($\vec{p}_{a}^{}$ + $\vec{p}_{b}^{}$), E = |$\vec{p}\,$| (energy rescaling)

  IRECOM=4

  Snowmass : p_t = p_{t, a} + p_{t, b},$\eta$ = ${1\over p_t}$($\eta_{a}^{}$p_{t, a} + $\eta_{b}^{}$p_{t, b}),$\varphi$ = ${1\over p_t}$($\varphi_{a}^{}$p_{t, a} + $\varphi_{b}^{}$p_{t, b}), E = |$\vec{p}\,$|

• P = ATH (A,I) calculates the theta angle (in radian) of the i'th vector of array A wrt. the + z-axis.
• P = VP2 (V) and P = AP2(A,I) returns the momentum squared of the particle V and A(i), respectively.
• P = VMASS2 (V) and P = AMASS2(A,I) returns the invariant mass squared of the particle V and A(i), respectively.

In the above functions and subroutines the variables are defined as follows :

      DOUBLE PRECISION A(4,*), B(4,*)
      DOUBLE PRECISION V(4)
      DOUBLE PRECISION P
      INTEGER          I,J,IRECOM