HepMC3 event record library
FourVector Class Reference

Detailed Description

Generic 4-vector.

Interpretation of its content depends on accessors used: it's much simpler to do this than to distinguish between space and momentum vectors via the type system (especially given the need for backward compatibility with HepMC2). Be sensible and don't call energy functions on spatial vectors! To avoid duplication, most definitions are only implemented on the spatial function names, with the energy-momentum functions as aliases.

This is not intended to be a fully featured 4-vector, but does contain the majority of common non-boosting functionality, as well as a few support operations on 4-vectors.

The implementations in this class are fully inlined.

Examples
basic_tree.cc.

Definition at line 36 of file FourVector.h.

#include <FourVector.h>

Public Member Functions

 FourVector ()
 Default constructor.
 
 FourVector (double xx, double yy, double zz, double ee)
 Sets all FourVector fields.
 
 FourVector (const FourVector &)=default
 Copy constructor.
 
 FourVector (FourVector &&)=default
 Move constructor.
 
FourVectoroperator= (const FourVector &)=default
 =
 
FourVectoroperator= (FourVector &&)=default
 =
 
Component accessors
void set (double x1, double x2, double x3, double x4)
 Set all FourVector fields, in order x,y,z,t.
 
void set_component (const int i, const double x)
 set component of position/displacement
 
double get_component (const int i) const
 get component of position/displacement
 
double x () const
 x-component of position/displacement
 
void set_x (double xx)
 Set x-component of position/displacement.
 
void setX (double xx)
 
double y () const
 y-component of position/displacement
 
void set_y (double yy)
 Set y-component of position/displacement.
 
void setY (double yy)
 
double z () const
 z-component of position/displacement
 
void set_z (double zz)
 Set z-component of position/displacement.
 
void setZ (double zz)
 
double t () const
 Time component of position/displacement.
 
void set_t (double tt)
 Set time component of position/displacement.
 
void setT (double tt)
 
double px () const
 x-component of momentum
 
void set_px (double pxx)
 Set x-component of momentum.
 
void setPx (double pxx)
 
double py () const
 y-component of momentum
 
void set_py (double pyy)
 Set y-component of momentum.
 
void setPy (double pyy)
 
double pz () const
 z-component of momentum
 
void set_pz (double pzz)
 Set z-component of momentum.
 
void setPz (double pzz)
 
double e () const
 Energy component of momentum.
 
void set_e (double ee)
 Set energy component of momentum.
 
void setE (double ee)
 
Computed properties
double length2 () const
 Squared magnitude of (x, y, z) 3-vector.
 
double length () const
 Magnitude of spatial (x, y, z) 3-vector.
 
double rho () const
 Magnitude of spatial (x, y, z) 3-vector, for HepMC2 compatibility.
 
double perp2 () const
 Squared magnitude of (x, y) vector.
 
double perp () const
 Magnitude of (x, y) vector.
 
double interval () const
 Spacetime invariant interval s^2 = t^2 - x^2 - y^2 - z^2.
 
double p3mod2 () const
 Squared magnitude of p3 = (px, py, pz) vector.
 
double p3mod () const
 Magnitude of p3 = (px, py, pz) vector.
 
double pt2 () const
 Squared transverse momentum px^2 + py^2.
 
double pt () const
 Transverse momentum.
 
double m2 () const
 Squared invariant mass m^2 = E^2 - px^2 - py^2 - pz^2.
 
double m () const
 Invariant mass. Returns -sqrt(-m) if e^2 - P^2 is negative.
 
double phi () const
 Azimuthal angle.
 
double theta () const
 Polar angle w.r.t. z direction.
 
double eta () const
 Pseudorapidity.
 
double rap () const
 Rapidity.
 
double abs_eta () const
 Absolute pseudorapidity.
 
double abs_rap () const
 Absolute rapidity.
 
double pseudoRapidity () const
 
Comparisons to another FourVector
bool is_zero () const
 Check if the length of this vertex is zero.
 
double delta_phi (const FourVector &v) const
 Signed azimuthal angle separation in [-pi, pi].
 
double delta_eta (const FourVector &v) const
 Pseudorapidity separation.
 
double delta_rap (const FourVector &v) const
 Rapidity separation.
 
double delta_r2_eta (const FourVector &v) const
 R_eta^2-distance separation dR^2 = dphi^2 + deta^2.
 
double delta_r_eta (const FourVector &v) const
 R_eta-distance separation dR = sqrt(dphi^2 + deta^2)
 
double delta_r2_rap (const FourVector &v) const
 R_rap^2-distance separation dR^2 = dphi^2 + drap^2.
 
double delta_r_rap (const FourVector &v) const
 R-rap-distance separation dR = sqrt(dphi^2 + drap^2)
 
Operators
bool operator== (const FourVector &rhs) const
 Equality.
 
bool operator!= (const FourVector &rhs) const
 Inequality.
 
FourVector operator+ (const FourVector &rhs) const
 Arithmetic operator +.
 
FourVector operator- (const FourVector &rhs) const
 Arithmetic operator -.
 
FourVector operator* (const double rhs) const
 Arithmetic operator * by scalar.
 
FourVector operator/ (const double rhs) const
 Arithmetic operator / by scalar.
 
void operator+= (const FourVector &rhs)
 Arithmetic operator +=.
 
void operator-= (const FourVector &rhs)
 Arithmetic operator -=.
 
void operator*= (const double rhs)
 Arithmetic operator *= by scalar.
 
void operator/= (const double rhs)
 Arithmetic operator /= by scalar.
 

Static Public Member Functions

static const FourVectorZERO_VECTOR ()
 Static null FourVector = (0,0,0,0)
 

Private Attributes

double m_v1
 px or x. Interpretation depends on accessors used
 
double m_v2
 py or y. Interpretation depends on accessors used
 
double m_v3
 pz or z. Interpretation depends on accessors used
 
double m_v4
 e or t. Interpretation depends on accessors used
 

Constructor & Destructor Documentation

◆ FourVector() [1/4]

FourVector ( )
inline

Default constructor.

Definition at line 40 of file FourVector.h.

References m_v1, m_v2, m_v3, and m_v4.

◆ FourVector() [2/4]

FourVector ( double xx,
double yy,
double zz,
double ee )
inline

Sets all FourVector fields.

Definition at line 43 of file FourVector.h.

References m_v1, m_v2, m_v3, and m_v4.

◆ FourVector() [3/4]

FourVector ( const FourVector & )
default

Copy constructor.

References FourVector().

◆ FourVector() [4/4]

FourVector ( FourVector && )
default

Move constructor.

References FourVector().

Member Function Documentation

◆ abs_eta()

double abs_eta ( ) const
inline

Absolute pseudorapidity.

Definition at line 190 of file FourVector.h.

References eta().

◆ abs_rap()

double abs_rap ( ) const
inline

Absolute rapidity.

Definition at line 192 of file FourVector.h.

References rap().

◆ delta_eta()

double delta_eta ( const FourVector & v) const
inline

Pseudorapidity separation.

Definition at line 218 of file FourVector.h.

References eta(), and FourVector().

◆ delta_phi()

double delta_phi ( const FourVector & v) const
inline

Signed azimuthal angle separation in [-pi, pi].

Definition at line 209 of file FourVector.h.

References FourVector(), M_PI, and phi().

◆ delta_r2_eta()

double delta_r2_eta ( const FourVector & v) const
inline

R_eta^2-distance separation dR^2 = dphi^2 + deta^2.

Definition at line 224 of file FourVector.h.

References delta_eta(), delta_phi(), and FourVector().

◆ delta_r2_rap()

double delta_r2_rap ( const FourVector & v) const
inline

R_rap^2-distance separation dR^2 = dphi^2 + drap^2.

Definition at line 234 of file FourVector.h.

References delta_phi(), delta_rap(), and FourVector().

◆ delta_r_eta()

double delta_r_eta ( const FourVector & v) const
inline

R_eta-distance separation dR = sqrt(dphi^2 + deta^2)

Definition at line 229 of file FourVector.h.

References delta_r2_eta(), and FourVector().

◆ delta_r_rap()

double delta_r_rap ( const FourVector & v) const
inline

R-rap-distance separation dR = sqrt(dphi^2 + drap^2)

Definition at line 239 of file FourVector.h.

References delta_r2_rap(), and FourVector().

◆ delta_rap()

double delta_rap ( const FourVector & v) const
inline

Rapidity separation.

Definition at line 221 of file FourVector.h.

References FourVector(), and rap().

◆ e()

double e ( ) const
inline

Energy component of momentum.

Definition at line 135 of file FourVector.h.

References t().

◆ eta()

double eta ( ) const
inline

Pseudorapidity.

Definition at line 178 of file FourVector.h.

References p3mod(), and pz().

◆ get_component()

double get_component ( const int i) const
inline

get component of position/displacement

Definition at line 74 of file FourVector.h.

References m_v1, m_v2, m_v3, and m_v4.

◆ interval()

double interval ( ) const
inline

Spacetime invariant interval s^2 = t^2 - x^2 - y^2 - z^2.

Definition at line 158 of file FourVector.h.

References length2(), and t().

◆ is_zero()

bool is_zero ( ) const
inline

Check if the length of this vertex is zero.

Definition at line 206 of file FourVector.h.

References t(), x(), y(), and z().

◆ length()

double length ( ) const
inline

Magnitude of spatial (x, y, z) 3-vector.

Definition at line 150 of file FourVector.h.

References length2().

◆ length2()

double length2 ( ) const
inline

Squared magnitude of (x, y, z) 3-vector.

Definition at line 148 of file FourVector.h.

References x(), y(), and z().

◆ m()

double m ( ) const
inline

Invariant mass. Returns -sqrt(-m) if e^2 - P^2 is negative.

Definition at line 171 of file FourVector.h.

References m2().

◆ m2()

double m2 ( ) const
inline

Squared invariant mass m^2 = E^2 - px^2 - py^2 - pz^2.

Definition at line 169 of file FourVector.h.

References interval().

◆ operator!=()

bool operator!= ( const FourVector & rhs) const
inline

Inequality.

Definition at line 254 of file FourVector.h.

References FourVector().

◆ operator*()

FourVector operator* ( const double rhs) const
inline

Arithmetic operator * by scalar.

Definition at line 265 of file FourVector.h.

References FourVector(), t(), x(), y(), and z().

◆ operator*=()

void operator*= ( const double rhs)
inline

Arithmetic operator *= by scalar.

Definition at line 288 of file FourVector.h.

References setT(), setX(), setY(), setZ(), t(), x(), y(), and z().

◆ operator+()

FourVector operator+ ( const FourVector & rhs) const
inline

Arithmetic operator +.

Definition at line 257 of file FourVector.h.

References FourVector(), t(), x(), y(), and z().

◆ operator+=()

void operator+= ( const FourVector & rhs)
inline

Arithmetic operator +=.

Definition at line 274 of file FourVector.h.

References FourVector(), setT(), setX(), setY(), setZ(), t(), x(), y(), and z().

◆ operator-()

FourVector operator- ( const FourVector & rhs) const
inline

Arithmetic operator -.

Definition at line 261 of file FourVector.h.

References FourVector(), t(), x(), y(), and z().

◆ operator-=()

void operator-= ( const FourVector & rhs)
inline

Arithmetic operator -=.

Definition at line 281 of file FourVector.h.

References FourVector(), setT(), setX(), setY(), setZ(), t(), x(), y(), and z().

◆ operator/()

FourVector operator/ ( const double rhs) const
inline

Arithmetic operator / by scalar.

Definition at line 269 of file FourVector.h.

References FourVector(), t(), x(), y(), and z().

◆ operator/=()

void operator/= ( const double rhs)
inline

Arithmetic operator /= by scalar.

Definition at line 295 of file FourVector.h.

References setT(), setX(), setY(), setZ(), t(), x(), y(), and z().

◆ operator=() [1/2]

FourVector & operator= ( const FourVector & )
default

=

References FourVector().

◆ operator=() [2/2]

FourVector & operator= ( FourVector && )
default

=

References FourVector().

◆ operator==()

bool operator== ( const FourVector & rhs) const
inline

Equality.

Definition at line 250 of file FourVector.h.

References FourVector(), t(), x(), y(), and z().

◆ p3mod()

double p3mod ( ) const
inline

Magnitude of p3 = (px, py, pz) vector.

Definition at line 163 of file FourVector.h.

References length().

◆ p3mod2()

double p3mod2 ( ) const
inline

Squared magnitude of p3 = (px, py, pz) vector.

Definition at line 161 of file FourVector.h.

References length2().

◆ perp()

double perp ( ) const
inline

Magnitude of (x, y) vector.

Definition at line 156 of file FourVector.h.

References perp2().

◆ perp2()

double perp2 ( ) const
inline

Squared magnitude of (x, y) vector.

Definition at line 154 of file FourVector.h.

References x(), and y().

◆ phi()

double phi ( ) const
inline

Azimuthal angle.

Definition at line 174 of file FourVector.h.

References x(), and y().

◆ pseudoRapidity()

double pseudoRapidity ( ) const
inline

Same as eta()

Deprecated
Prefer 'only one way to do it', and we don't have equivalent long names for e.g. pid, phi or eta

Definition at line 197 of file FourVector.h.

References eta().

◆ pt()

double pt ( ) const
inline

Transverse momentum.

Definition at line 167 of file FourVector.h.

References perp().

◆ pt2()

double pt2 ( ) const
inline

Squared transverse momentum px^2 + py^2.

Definition at line 165 of file FourVector.h.

References perp2().

◆ px()

double px ( ) const
inline

x-component of momentum

Definition at line 114 of file FourVector.h.

References x().

◆ py()

double py ( ) const
inline

y-component of momentum

Definition at line 121 of file FourVector.h.

References y().

◆ pz()

double pz ( ) const
inline

z-component of momentum

Definition at line 128 of file FourVector.h.

References z().

◆ rap()

double rap ( ) const
inline

Rapidity.

Definition at line 184 of file FourVector.h.

References e(), and pz().

◆ rho()

double rho ( ) const
inline

Magnitude of spatial (x, y, z) 3-vector, for HepMC2 compatibility.

Definition at line 152 of file FourVector.h.

References length().

◆ set()

void set ( double x1,
double x2,
double x3,
double x4 )
inline

Set all FourVector fields, in order x,y,z,t.

Definition at line 58 of file FourVector.h.

References m_v1, m_v2, m_v3, and m_v4.

◆ set_component()

void set_component ( const int i,
const double x )
inline

set component of position/displacement

Definition at line 66 of file FourVector.h.

References m_v1, m_v2, m_v3, m_v4, and x().

◆ set_e()

void set_e ( double ee)
inline

Set energy component of momentum.

Definition at line 137 of file FourVector.h.

References set_t().

◆ set_px()

void set_px ( double pxx)
inline

Set x-component of momentum.

Definition at line 116 of file FourVector.h.

References set_x().

◆ set_py()

void set_py ( double pyy)
inline

Set y-component of momentum.

Definition at line 123 of file FourVector.h.

References set_y().

◆ set_pz()

void set_pz ( double pzz)
inline

Set z-component of momentum.

Definition at line 130 of file FourVector.h.

References set_z().

◆ set_t()

void set_t ( double tt)
inline

Set time component of position/displacement.

Definition at line 108 of file FourVector.h.

References m_v4.

◆ set_x()

void set_x ( double xx)
inline

Set x-component of position/displacement.

Definition at line 87 of file FourVector.h.

References m_v1.

◆ set_y()

void set_y ( double yy)
inline

Set y-component of position/displacement.

Definition at line 94 of file FourVector.h.

References m_v2.

◆ set_z()

void set_z ( double zz)
inline

Set z-component of position/displacement.

Definition at line 101 of file FourVector.h.

References m_v3.

◆ setE()

void setE ( double ee)
inline
Deprecated
Prefer the HepMC-style set_y() function

Definition at line 139 of file FourVector.h.

References set_e().

◆ setPx()

void setPx ( double pxx)
inline
Deprecated
Prefer the HepMC-style set_px() function

Definition at line 118 of file FourVector.h.

References set_px().

◆ setPy()

void setPy ( double pyy)
inline
Deprecated
Prefer the HepMC-style set_py() function

Definition at line 125 of file FourVector.h.

References set_py().

◆ setPz()

void setPz ( double pzz)
inline
Deprecated
Prefer the HepMC-style set_pz() function

Definition at line 132 of file FourVector.h.

References set_pz().

◆ setT()

void setT ( double tt)
inline
Deprecated
Prefer the HepMC-style set_t() function

Definition at line 110 of file FourVector.h.

References set_t().

◆ setX()

void setX ( double xx)
inline
Deprecated
Prefer the HepMC-style set_x() function

Definition at line 89 of file FourVector.h.

References set_x().

◆ setY()

void setY ( double yy)
inline
Deprecated
Prefer the HepMC-style set_y() function

Definition at line 96 of file FourVector.h.

References set_y().

◆ setZ()

void setZ ( double zz)
inline
Deprecated
Prefer the HepMC-style set_z() function

Definition at line 103 of file FourVector.h.

References set_z().

◆ t()

double t ( ) const
inline

Time component of position/displacement.

Definition at line 106 of file FourVector.h.

References m_v4.

◆ theta()

double theta ( ) const
inline

Polar angle w.r.t. z direction.

Definition at line 176 of file FourVector.h.

References perp(), and z().

◆ x()

double x ( ) const
inline

x-component of position/displacement

Definition at line 85 of file FourVector.h.

References m_v1.

◆ y()

double y ( ) const
inline

y-component of position/displacement

Definition at line 92 of file FourVector.h.

References m_v2.

◆ z()

double z ( ) const
inline

z-component of position/displacement

Definition at line 99 of file FourVector.h.

References m_v3.

◆ ZERO_VECTOR()

static const FourVector & ZERO_VECTOR ( )
inlinestatic

Static null FourVector = (0,0,0,0)

Definition at line 306 of file FourVector.h.

References FourVector().

Field Documentation

◆ m_v1

double m_v1
private

px or x. Interpretation depends on accessors used

Definition at line 314 of file FourVector.h.

◆ m_v2

double m_v2
private

py or y. Interpretation depends on accessors used

Definition at line 315 of file FourVector.h.

◆ m_v3

double m_v3
private

pz or z. Interpretation depends on accessors used

Definition at line 316 of file FourVector.h.

◆ m_v4

double m_v4
private

e or t. Interpretation depends on accessors used

Definition at line 317 of file FourVector.h.


The documentation for this class was generated from the following file: