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Comparing UserCode/MitHzz4l/Angles/src/Angles.cc (file contents):
Revision 1.1 by khahn, Thu Sep 8 13:33:18 2011 UTC vs.
Revision 1.7 by dkralph, Tue Jan 15 09:40:10 2013 UTC

#	Line 1 | Line 0
1	–	#include "Angles.h"
2	–	#include <iostream>
3	–
4	–	void getAngles( LabVectors &l,
5	–	Angles &a ) {
6	–
7	–	//
8	–	// define the frames
9	–	// --------------------------------------------------------------------------------------------------
10	–	TVector3 Xframe  = l.vec4l.BoostVector();
11	–	TVector3 Z1frame = l.vecz1.BoostVector();
12	–	TVector3 Z2frame = l.vecz2.BoostVector();
13	–
14	–	//
15	–	// costheta(l1m,X) in Z1 frame
16	–	// --------------------------------------------------------------------------------------------------
17	–	TLorentzVector vecl1m_in_Z1frame( l.vecl1m ); // make a copies of the vectors
18	–	TLorentzVector vec4l_in_Z1frame( l.vec4l );   //
19	–	vecl1m_in_Z1frame.Boost( -1*Z1frame );        // now go to the Z1 rest frame
20	–	vec4l_in_Z1frame.Boost( -1*Z1frame );         //
21	–	a.costheta1
22	–	= vecl1m_in_Z1frame.Vect().Dot(-1*vec4l_in_Z1frame.Vect()) /
23	–	(vecl1m_in_Z1frame.Vect().Mag()*vec4l_in_Z1frame.Vect().Mag());
24	–
25	–	//
26	–	// costheta(l3,X) in Z2 frame
27	–	// --------------------------------------------------------------------------------------------------
28	–	TLorentzVector vecl2m_in_Z2frame( l.vecl2m ); // make copies of the vectors
29	–	TLorentzVector vec4l_in_Z2frame( l.vec4l );   //
30	–	vecl2m_in_Z2frame.Boost( -1*Z2frame );        // now go to the Z2 rest frame
31	–	vec4l_in_Z2frame.Boost( -1*Z2frame );
32	–	a.costheta2 =
33	–	vecl2m_in_Z2frame.Vect().Dot(-1*vec4l_in_Z2frame.Vect()) /
34	–	(vecl2m_in_Z2frame.Vect().Mag()*vec4l_in_Z2frame.Vect().Mag());
35	–
36	–
37	–	//
38	–	// Phi(Z1,Z2) in X frame
39	–	// --------------------------------------------------------------------------------------------------
40	–
41	–	// this is essentially what they do and it reproduces their numbers,
42	–	// it's the angle between l1 and the z2 decay plane in the Z1 frame
43	–	TLorentzVector vecz2_in_Z1frame( l.vecz2 );      //
44	–	TLorentzVector vecl2m_in_Z1frame( l.vecl2m );    //
45	–	TLorentzVector vecl2p_in_Z1frame( l.vecl2p );    //
46	–	vecz2_in_Z1frame.Boost( -1*Z1frame );            //
47	–	vecl2m_in_Z1frame.Boost( -1*Z1frame );           //
48	–	vecl2p_in_Z1frame.Boost( -1*Z1frame );           //
49	–
50	–	//
51	–	// define the Z2 coordinate system in the Z1 frame
52	–	// x : opposite the Z2 dir, lies in the Z2 decay plane
53	–	// z : orthogonal to the Z2 decay plane
54	–	// y : orthogonal to x&z, lies in the Z2 decay plane
55	–	TVector3 nnewX = ( -1*vecz2_in_Z1frame.Vect()).Unit();
56	–	TVector3 nnewZ = (vecl2m_in_Z1frame.Vect().Cross(vecl2p_in_Z1frame.Vect())).Unit();
57	–	TVector3 nnewY = nnewZ.Cross(nnewX).Unit();
58	–	TRotation rotation2;
59	–	rotation2 = (rotation2.RotateAxes( nnewX, nnewY, nnewZ )).Inverse();
60	–	TVector3 vecl1m_in_Z2coords_Z1frame  = vecl1m_in_Z1frame.Vect().Transform(rotation2);
61	–
62	–	//
63	–	// axes are redfined so that Phi is the angle between the Z1 orthogonal
64	–	// and the Z2 decay plane as given by y
65	–	//
66	–	TRotation rotation3;
67	–	TVector3 nnnewX( 0,1,0 );
68	–	TVector3 nnnewY( 0,0,1 );
69	–	TVector3 nnnewZ( 1,0,0 );
70	–	rotation3 = (rotation3.RotateAxes( nnnewX, nnnewY, nnnewZ )).Inverse();
71	–	TVector3 vecl1m_in_Z2coords_redefined_Z1frame = vecl1m_in_Z2coords_Z1frame.Transform(rotation3);
72	–	a.Phi = vecl1m_in_Z2coords_redefined_Z1frame.Phi();
73	–
74	–
75	–	//
76	–	// rather, I'd expect something like this ...
77	–	//
78	–	TLorentzVector vecl1p_in_Xframe( l.vecl1p ); // make a copies of the vectors
79	–	TLorentzVector vecl1m_in_Xframe( l.vecl1m ); //
80	–	TLorentzVector vecl2p_in_Xframe( l.vecl2p ); //
81	–	TLorentzVector vecl2m_in_Xframe( l.vecl2m ); //
82	–
83	–	vecl1p_in_Xframe.Boost( -1*Xframe );         // go to the X rest frame
84	–	vecl1m_in_Xframe.Boost( -1*Xframe );         //
85	–	vecl2p_in_Xframe.Boost( -1*Xframe );         //
86	–	vecl2m_in_Xframe.Boost( -1*Xframe );         //
87	–
88	–	/*
89	–	// sanity check ...
90	–	TLorentzVector z1inX = vecl1p_in_Xframe+vecl1m_in_Xframe;
91	–	TLorentzVector z2inX = vecl2p_in_Xframe+vecl2m_in_Xframe;
92	–	float dotz1z2 = z1inX.Vect().Dot(z2inX.Vect()) / (z1inX.Vect().Mag()*z2inX.Vect().Mag());
93	–	std::cout << "dotz1z2: " << dotz1z2 << std::endl;
94	–	*/
95	–
96	–	TVector3 Z1ortho_in_Xframe =                                         // define the decay planes via the orthogonals
97	–	vecl1m_in_Xframe.Vect().Cross(vecl1p_in_Xframe.Vect());
98	–	TVector3 Z2ortho_in_Xframe =
99	–	vecl2m_in_Xframe.Vect().Cross(vecl2p_in_Xframe.Vect());
100	–
101	–	/*
102	–	// sanity check  ... why are these small but not exactly zero ???
103	–	float z1odot = Z1ortho_in_Xframe.Dot(z1inX.Vect())/(Z1ortho_in_Xframe.Mag()*z1inX.Vect().Mag());
104	–	float z2odot = Z2ortho_in_Xframe.Dot(z2inX.Vect())/(Z2ortho_in_Xframe.Mag()*z2inX.Vect().Mag());
105	–	float l1podot = Z1ortho_in_Xframe.Dot(vecl1p_in_Xframe.Vect())/(Z1ortho_in_Xframe.Mag()*vecl1p_in_Xframe.Vect().Mag());
106	–	float l1modot = Z1ortho_in_Xframe.Dot(vecl1m_in_Xframe.Vect())/(Z1ortho_in_Xframe.Mag()*vecl1m_in_Xframe.Vect().Mag());
107	–	std::cout << "Z1ortho_in_Xframe.Dot(z1inX): " << z1odot << "\t"
108	–	<< "Z2ortho_in_Xframe.Dot(z2inX): " << z2odot << "\t"
109	–	<< "Z1ortho_in_Xframe.Dot(veclp1_in_Xframe) : " << l1podot << "\t"
110	–	<< "Z1ortho_in_Xframe.Dot(veclm1_in_Xframe) : " << l1modot << "\t"
111	–	<< std::endl;
112	–	*/
113	–
114	–
115	–	//  a.Phi =   Z1ortho_in_Xframe.DeltaPhi(Z2ortho_in_Xframe);
116	–	//a.Phi =   Z1ortho_in_Xframe.Angle(Z2ortho_in_Xframe);
117	–
118	–
119	–
120	–	//
121	–	// costheta*(Z1,pp) in X frame
122	–	// --------------------------------------------------------------------------------------------------
123	–	TLorentzVector vecz1_in_Xframe( l.vecz1 );        // make a copies of the vectors
124	–	TLorentzVector vecpp_in_Xframe( 0., 0., 1., 0. ); // define pp axis
125	–
126	–	vecz1_in_Xframe.Boost( -1*Xframe );         // go to the X rest frame
127	–	vecpp_in_Xframe.Boost( -1*Xframe );         //
128	–
129	–	a.costhetastar =
130	–	vecz1_in_Xframe.Vect().Dot(vecpp_in_Xframe.Vect()) /
131	–	(vecz1_in_Xframe.Vect().Mag()*vecpp_in_Xframe.Vect().Mag());
132	–
133	–
134	–	//
135	–	// Phi1(Z1,pp) in X frame
136	–	// --------------------------------------------------------------------------------------------------
137	–
138	–	// define the Z1 decay plane in the Xframe
139	–	// y: orthogonal to the Z1 decay plane
140	–	// x: lies in the Z1 decay plane, but orthogonal to Z1
141	–	// z: z1 in Xframe
142	–	TVector3 newY = (vecl1p_in_Xframe.Vect().Unit().Cross(vecl1m_in_Xframe.Vect().Unit())).Unit();
143	–	TVector3 newX = (newY.Cross(vecz1_in_Xframe.Vect().Unit())).Unit();
144	–	TVector3 newZ( (vecz1_in_Xframe.Vect()).Unit() );
145	–
146	–	TRotation rotation;
147	–	rotation = (rotation.RotateAxes( newX, newY, newZ )).Inverse();
148	–	TVector3 vecpp( 0., 0., 1. );
149	–	TVector3 vecpp_in_Z1coords_Xframe  = vecpp.Transform(rotation);
150	–	a.Phi1 = vecpp_in_Z1coords_Xframe.Phi();
151	–
152	–	a.mz1 = (l.vecl1m+l.vecl1p).M();
153	–	a.mz2 = (l.vecl2m+l.vecl2p).M();
154	–	a.m4l = (l.vec4l).M();
155	–
156	–	};
157	–
158	–

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