| 1 |
sixie |
1.1 |
/*****************************************************************************
|
| 2 |
|
|
* Project: CMS detector at the CERN
|
| 3 |
|
|
*
|
| 4 |
|
|
* Package: PhysicsTools/TagAndProbe/RooCMSShape
|
| 5 |
|
|
*
|
| 6 |
|
|
*
|
| 7 |
|
|
* Authors:
|
| 8 |
|
|
* Nadia Adam, Princeton - neadam@princeton.edu
|
| 9 |
|
|
* Adam Hunt, Princeton - ahunt@princeton.edu
|
| 10 |
|
|
* Kalanand Mishra, Fermilab - kalanand@fnal.gov
|
| 11 |
|
|
*
|
| 12 |
|
|
* Description:
|
| 13 |
|
|
* Defines a probability density function which has exponential decay
|
| 14 |
|
|
* distribution at high mass beyond the pole position (say, Z peak)
|
| 15 |
|
|
* but turns over (i.e., error function) at low mass due to threshold
|
| 16 |
|
|
* effect. We use this to model the background shape in Z->ll invariant
|
| 17 |
|
|
* mass.
|
| 18 |
|
|
* History:
|
| 19 |
|
|
*
|
| 20 |
|
|
*
|
| 21 |
|
|
* Copyright (C) 2008 FNAL
|
| 22 |
|
|
*****************************************************************************/
|
| 23 |
|
|
|
| 24 |
|
|
#include "RooCMSShape.h"
|
| 25 |
|
|
|
| 26 |
|
|
ClassImp(RooCMSShape)
|
| 27 |
|
|
|
| 28 |
|
|
RooCMSShape::RooCMSShape(const char *name, const char *title,
|
| 29 |
|
|
RooAbsReal& _x,
|
| 30 |
|
|
RooAbsReal& _alpha,
|
| 31 |
|
|
RooAbsReal& _beta,
|
| 32 |
|
|
RooAbsReal& _gamma,
|
| 33 |
|
|
RooAbsReal& _peak) :
|
| 34 |
|
|
RooAbsPdf(name,title),
|
| 35 |
|
|
x("x","x",this,_x),
|
| 36 |
|
|
alpha("alpha","alpha",this,_alpha),
|
| 37 |
|
|
beta("beta","beta",this,_beta),
|
| 38 |
|
|
gamma("gamma","gamma",this,_gamma),
|
| 39 |
|
|
peak("peak","peak",this,_peak)
|
| 40 |
|
|
{ }
|
| 41 |
|
|
|
| 42 |
|
|
|
| 43 |
|
|
RooCMSShape::RooCMSShape(const RooCMSShape& other, const char* name):
|
| 44 |
|
|
RooAbsPdf(other,name),
|
| 45 |
|
|
x("x",this,other.x),
|
| 46 |
|
|
alpha("alpha",this,other.alpha),
|
| 47 |
|
|
beta("beta",this,other.beta),
|
| 48 |
|
|
gamma("gamma",this,other.gamma),
|
| 49 |
|
|
peak("peak",this,other.peak)
|
| 50 |
|
|
{ }
|
| 51 |
|
|
|
| 52 |
|
|
|
| 53 |
|
|
|
| 54 |
|
|
Double_t RooCMSShape::evaluate() const
|
| 55 |
|
|
{
|
| 56 |
|
|
// ENTER EXPRESSION IN TERMS OF VARIABLE ARGUMENTS HERE
|
| 57 |
|
|
|
| 58 |
|
|
//Double_t erf = TMath::Erfc((alpha - x) * beta);
|
| 59 |
|
|
Double_t erf = RooMath::erfc((alpha - x) * beta);
|
| 60 |
|
|
Double_t u = (x - peak)*gamma;
|
| 61 |
|
|
|
| 62 |
|
|
if(u < -70) u = 1e20;
|
| 63 |
|
|
else if( u>70 ) u = 0;
|
| 64 |
|
|
else u = exp(-u); //exponential decay
|
| 65 |
|
|
return erf*u;
|
| 66 |
|
|
}
|
