source: trunk/SISCone/momentum.h@ 23

Last change on this file since 23 was 20, checked in by Pavel Demin, 16 years ago

add SISCone library

File size: 5.5 KB
Line 
1// -*- C++ -*-
2///////////////////////////////////////////////////////////////////////////////
3// File: momentum.h //
4// Description: header file for 4-momentum class Cmomentum //
5// This file is part of the SISCone project. //
6// For more details, see http://projects.hepforge.org/siscone //
7// //
8// Copyright (c) 2006 Gavin Salam and Gregory Soyez //
9// //
10// This program is free software; you can redistribute it and/or modify //
11// it under the terms of the GNU General Public License as published by //
12// the Free Software Foundation; either version 2 of the License, or //
13// (at your option) any later version. //
14// //
15// This program is distributed in the hope that it will be useful, //
16// but WITHOUT ANY WARRANTY; without even the implied warranty of //
17// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
18// GNU General Public License for more details. //
19// //
20// You should have received a copy of the GNU General Public License //
21// along with this program; if not, write to the Free Software //
22// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA //
23// //
24// $Revision: 1.1 $//
25// $Date: 2008-10-02 15:20:26 $//
26///////////////////////////////////////////////////////////////////////////////
27
28#ifndef __VECTOR_H__
29#define __VECTOR_H__
30
31#include <vector>
32#include <math.h>
33#include "reference.h"
34#include "geom_2d.h"
35#include "defines.h"
36
37namespace siscone{
38
39/**
40 * \class Cmomentum
41 * \brief base class for dynamic coordinates management
42 *
43 * This class contains the information for particle or group of
44 * particles management.
45 * It includes all Lorentz properties as well as tools for summing them.
46 * Note: 'sums' over phi angles are indeed averages. This allows to
47 * deal with periodicity at each step
48 */
49class Cmomentum{
50 public:
51 /// default ctor
52 Cmomentum();
53
54 /// ctor with initialisation
55 Cmomentum(double _px, double _py, double _pz, double _E);
56
57 /// ctor with detailed initialisation
58 Cmomentum(double _eta, double _phi, Creference _ref);
59
60 /// default dtor
61 ~Cmomentum();
62
63 /// computes pT
64 inline double perp() const {return sqrt(perp2());}
65
66 /// computes pT^2
67 inline double perp2() const {return px*px+py*py;}
68
69 /// computes m
70 inline double mass() const {return sqrt(mass2());}
71
72 /// computes m^2
73 inline double mass2() const {return perpmass2()-perp2();}
74
75 /// transverse mass, mt = sqrt(pt^2+m^2) = sqrt(E^2 - pz^2)
76 inline double perpmass() const {return sqrt((E-pz)*(E+pz));}
77
78 /// transverse mass squared, mt^2 = pt^2+m^2 = E^2 - pz^2
79 inline double perpmass2() const {return (E-pz)*(E+pz);}
80
81 /// computes transverse energy
82 inline double Et() const {return E/sqrt(1.0+pz*pz/perp2());}
83
84 /// computes transverse energy (squared)
85 inline double Et2() const {return E*E/(1.0+pz*pz/perp2());}
86
87 /// assignment of vectors
88 Cmomentum& operator = (const Cmomentum &v);
89
90 /// addition of vectors
91 /// !!! WARNING !!! no updating of eta and phi !!!
92 const Cmomentum operator + (const Cmomentum &v);
93
94 /// incrementation of vectors
95 /// !!! WARNING !!! no updating of eta and phi !!!
96 Cmomentum& operator += (const Cmomentum &v);
97
98 /// decrementation of vectors
99 /// !!! WARNING !!! no updating of eta and phi !!!
100 Cmomentum& operator -= (const Cmomentum &v);
101
102 /// build eta-phi from 4-momentum info
103 /// !!! WARNING !!!
104 /// !!! computing eta and phi is time-consuming !!!
105 /// !!! use this whenever you need eta or phi !!!
106 /// !!! automatically called for single-particle !!!
107 void build_etaphi();
108
109 double px; ///< x-momentum
110 double py; ///< y-momentum
111 double pz; ///< z-momentum
112 double E; ///< energy
113
114 double eta; ///< particle pseudo-rapidity
115 double phi; ///< particle azimuthal angle
116 int parent_index; ///< particle number in the parent list
117 int index; ///< internal particle number
118
119 //////////////////////////////////////////////
120 // the following part is used for checksums //
121 //////////////////////////////////////////////
122 Creference ref; ///< reference number for the vector
123};
124
125/// ordering of two vectors
126/// this is by default done w.r.t. their references
127bool operator < (const Cmomentum &v1, const Cmomentum &v2);
128
129/// ordering of vectors in eta (e.g. used in collinear tests)
130bool momentum_eta_less(const Cmomentum &v1, const Cmomentum &v2);
131
132/// ordering of vectors in pt
133bool momentum_pt_less(const Cmomentum &v1, const Cmomentum &v2);
134
135
136//////////////////////////
137// some handy utilities //
138//////////////////////////
139
140/// get distance between to eta-phi points
141/// \param eta eta coordinate of first point
142/// \param phi phi coordinate of first point
143/// \param v vector defining the second point
144inline double get_distance(double eta, double phi, Cmomentum *v){
145 double dx, dy;
146
147 dx = eta - v->eta;
148 dy = fabs(phi - v->phi);
149 if (dy>M_PI)
150 dy -= twopi;
151
152 return dx*dx+dy*dy;
153}
154
155}
156
157#endif
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