- Attention
 TLorentzVector is a legacy class. It is slower and worse for serialization than the recommended superior alternative ROOT::Math::LorentzVector. ROOT provides specialisations of the ROOT::Math::LorentzVector template which offer superior runtime performance, i.e.:
- ROOT::Math::PtEtaPhiMVector based on pt (rho),eta,phi and M (t) coordinates in double precision
 
- ROOT::Math::PtEtaPhiEVector based on pt (rho),eta,phi and E (t) coordinates in double precision
 
- ROOT::Math::PxPyPzMVector based on px,py,pz and M (mass) coordinates in double precision
 
- ROOT::Math::PxPyPzEVector based on px,py,pz and E (energy) coordinates in double precision
 
- ROOT::Math::XYZTVector based on x,y,z,t coordinates (cartesian) in double precision (same as PxPyPzEVector)
 
- ROOT::Math::XYZTVectorF based on x,y,z,t coordinates (cartesian) in float precision (same as PxPyPzEVector but float)
 
More details can be found in the documentation of the Physics Vectors package. 
Description
TLorentzVector is a general four-vector class, which can be used either for the description of position and time (x,y,z,t) or momentum and energy (px,py,pz,E).
Declaration
TLorentzVector has been implemented as a set a TVector3 and a Double_t variable. By default all components are initialized by zero.
For backward compatibility there are two constructors from an Double_t and Float_t C array.
Access to the components
There are two sets of access functions to the components of a LorentzVector: X(), Y(), Z(), T() and Px(), Py(), Pz() and E(). Both sets return the same values but the first set is more relevant for use where TLorentzVector describes a combination of position and time and the second set is more relevant where TLorentzVector describes momentum and energy:
The components of TLorentzVector can also accessed by index:
You can use the Vect() member function to get the vector component of TLorentzVector:
winID h TVirtualViewer3D TVirtualGLPainter p
 
 For setting components also two sets of member functions can be used:
v.SetX(1.);        
or    v.SetPx(1.);
 
...                               ...
To set more the one component by one call you can use the SetVect() function for the TVector3 part or SetXYZT(), SetPxPyPzE(). For convenience there is
also a SetXYZM():
v.SetPxPyPzE(px,py,pz,
e);
 
 
Vector components in non-cartesian coordinate systems
There are a couple of member functions to get and set the TVector3 part of the parameters in spherical coordinate systems:
 
ROOT::Detail::TRangeCast< T, true > TRangeDynCast
TRangeDynCast is an adapter class that allows the typed iteration through a TCollection.
 
 or get information about the r-coordinate in cylindrical systems:
for convenience there are two more set functions SetPtEtaPhiE(pt,eta,phi,e); and SetPtEtaPhiM(pt,eta,phi,m);
Arithmetic and comparison operators
The TLorentzVector class provides operators to add, subtract or compare four-vectors:
Magnitude/Invariant mass, beta, gamma, scalar product
The scalar product of two four-vectors is calculated with the (-,-,-,+) metric,
i.e. s = v1*v2 = t1*t2-x1*x2-y1*y2-z1*z2 The magnitude squared mag2 of a four-vector is therefore:
 It mag2 is negative mag = -Sqrt(-mag*mag). The member functions are:
Since in case of momentum and energy the magnitude has the meaning of invariant mass TLorentzVector provides the more meaningful aliases M2() and M(); The member functions Beta() and Gamma() returns beta and gamma = 1/Sqrt(1-beta*beta). 
Lorentz boost
A boost in a general direction can be parameterised with three parameters which can be taken as the components of a three vector b = (bx,by,bz). With x = (x,y,z) and gamma = 1/Sqrt(1-beta*beta) (beta being the module of vector b), an arbitrary active Lorentz boost transformation (from the rod frame to the original frame) can be written as:
x = 
x' + (gamma-1)/(beta*beta) * (b*x') * 
b + gamma * t
' * b 
The member function Boost() performs a boost transformation from the rod frame to the original frame. BoostVector() returns a TVector3 of the spatial components divided by the time component:
Rotations
There are four sets of functions to rotate the TVector3 component of a TLorentzVector:
rotation around axes
rotation around an arbitrary axis
v.Rotate(TMath::Pi()/4., v1); // rotation around v1
transformation from rotated frame
Option_t Option_t TPoint TPoint const char GetTextMagnitude GetFillStyle GetLineColor GetLineWidth GetMarkerStyle GetTextAlign GetTextColor GetTextSize void char Point_t Rectangle_t WindowAttributes_t Float_t r
 
<div class="legacybox"><h2>Legacy Code</h2> TRotation is a legacy interface: there will be no bug fix...
 
 
Misc
Angle between two vectors
Light-cone components
Member functions Plus() and Minus() return the positive and negative light-cone components:
CAVEAT: The values returned are T{+,-}Z. It is known that some authors find it easier to define these components as (T{+,-}Z)/sqrt(2). Thus check what definition is used in the physics you're working in and adapt your code accordingly.
A general Lorentz transformation see class TLorentzRotation can be used by the Transform() member function, the *= or operator of the TLorentzRotation class:
<div class="legacybox"><h2>Legacy Code</h2> TLorentzRotation is a legacy interface: there will be no ...
 
  
Definition at line 31 of file TLorentzVector.h.
 | 
|   | TLorentzVector () | 
|   | 
|   | TLorentzVector (const Double_t *carray) | 
|   | 
|   | TLorentzVector (const Float_t *carray) | 
|   | 
|   | TLorentzVector (const TLorentzVector &lorentzvector) | 
|   | 
|   | TLorentzVector (const TVector3 &vector3, Double_t t) | 
|   | 
|   | TLorentzVector (Double_t x, Double_t y, Double_t z, Double_t t) | 
|   | 
|   | ~TLorentzVector () override | 
|   | 
| Double_t  | Angle (const TVector3 &v) const | 
|   | 
| Double_t  | Beta () const | 
|   | 
| void  | Boost (const TVector3 &) | 
|   | 
| void  | Boost (Double_t, Double_t, Double_t) | 
|   | 
| TVector3  | BoostVector () const | 
|   | 
| Double_t  | CosTheta () const | 
|   | 
| Double_t  | DeltaPhi (const TLorentzVector &) const | 
|   | 
| Double_t  | DeltaR (const TLorentzVector &, Bool_t useRapidity=kFALSE) const | 
|   | 
| Double_t  | Dot (const TLorentzVector &) const | 
|   | 
| Double_t  | DrEtaPhi (const TLorentzVector &) const | 
|   | 
| Double_t  | DrRapidityPhi (const TLorentzVector &) const | 
|   | 
| Double_t  | E () const | 
|   | 
| Double_t  | Energy () const | 
|   | 
| Double_t  | Et () const | 
|   | 
| Double_t  | Et (const TVector3 &) const | 
|   | 
| Double_t  | Et2 () const | 
|   | 
| Double_t  | Et2 (const TVector3 &) const | 
|   | 
| Double_t  | Eta () const | 
|   | 
| TVector2  | EtaPhiVector () | 
|   | 
| Double_t  | Gamma () const | 
|   | 
| void  | GetXYZT (Double_t *carray) const | 
|   | 
| void  | GetXYZT (Float_t *carray) const | 
|   | 
| TClass *  | IsA () const override | 
|   | 
| Double_t  | M () const | 
|   | 
| Double_t  | M2 () const | 
|   | 
| Double_t  | Mag () const | 
|   | 
| Double_t  | Mag2 () const | 
|   | 
| Double_t  | Minus () const | 
|   | 
| Double_t  | Mt () const | 
|   | 
| Double_t  | Mt2 () const | 
|   | 
|   | operator ROOT::Math::PxPyPzEVector () const | 
|   | 
| Bool_t  | operator!= (const TLorentzVector &) const | 
|   | 
| Double_t &  | operator() (int i) | 
|   | 
| Double_t  | operator() (int i) const | 
|   | 
| Double_t  | operator* (const TLorentzVector &) const | 
|   | 
| TLorentzVector  | operator* (Double_t a) const | 
|   | 
| TLorentzVector &  | operator*= (const TLorentzRotation &) | 
|   | 
| TLorentzVector &  | operator*= (const TRotation &) | 
|   | 
| TLorentzVector &  | operator*= (Double_t a) | 
|   | 
| TLorentzVector  | operator+ (const TLorentzVector &) const | 
|   | 
| TLorentzVector &  | operator+= (const TLorentzVector &) | 
|   | 
| TLorentzVector  | operator- () const | 
|   | 
| TLorentzVector  | operator- (const TLorentzVector &) const | 
|   | 
| TLorentzVector &  | operator-= (const TLorentzVector &) | 
|   | 
| TLorentzVector &  | operator= (const TLorentzVector &) | 
|   | 
| Bool_t  | operator== (const TLorentzVector &) const | 
|   | 
| Double_t &  | operator[] (int i) | 
|   | 
| Double_t  | operator[] (int i) const | 
|   | 
| Double_t  | P () const | 
|   | 
| Double_t  | Perp () const | 
|   | 
| Double_t  | Perp (const TVector3 &v) const | 
|   | 
| Double_t  | Perp2 () const | 
|   | 
| Double_t  | Perp2 (const TVector3 &v) const | 
|   | 
| Double_t  | Phi () const | 
|   | 
| Double_t  | Plus () const | 
|   | 
| void  | Print (Option_t *option="") const override | 
|   | Print the TLorentz vector components as (x,y,z,t) and (P,eta,phi,E) representations.  
  | 
|   | 
| Double_t  | PseudoRapidity () const | 
|   | 
| Double_t  | Pt () const | 
|   | 
| Double_t  | Pt (const TVector3 &v) const | 
|   | 
| Double_t  | Px () const | 
|   | 
| Double_t  | Py () const | 
|   | 
| Double_t  | Pz () const | 
|   | 
| Double_t  | Rapidity () const | 
|   | 
| Double_t  | Rho () const | 
|   | 
| void  | Rotate (Double_t, const TVector3 &) | 
|   | 
| void  | RotateUz (const TVector3 &newUzVector) | 
|   | 
| void  | RotateX (Double_t angle) | 
|   | 
| void  | RotateY (Double_t angle) | 
|   | 
| void  | RotateZ (Double_t angle) | 
|   | 
| void  | SetE (Double_t a) | 
|   | 
| void  | SetPerp (Double_t) | 
|   | 
| void  | SetPhi (Double_t phi) | 
|   | 
| void  | SetPtEtaPhiE (Double_t pt, Double_t eta, Double_t phi, Double_t e) | 
|   | 
| void  | SetPtEtaPhiM (Double_t pt, Double_t eta, Double_t phi, Double_t m) | 
|   | 
| void  | SetPx (Double_t a) | 
|   | 
| void  | SetPxPyPzE (Double_t px, Double_t py, Double_t pz, Double_t e) | 
|   | 
| void  | SetPy (Double_t a) | 
|   | 
| void  | SetPz (Double_t a) | 
|   | 
| void  | SetRho (Double_t rho) | 
|   | 
| void  | SetT (Double_t a) | 
|   | 
| void  | SetTheta (Double_t theta) | 
|   | 
| void  | SetVect (const TVector3 &vect3) | 
|   | 
| void  | SetVectM (const TVector3 &spatial, Double_t mass) | 
|   | 
| void  | SetVectMag (const TVector3 &spatial, Double_t magnitude) | 
|   | 
| void  | SetX (Double_t a) | 
|   | 
| void  | SetXYZM (Double_t x, Double_t y, Double_t z, Double_t m) | 
|   | 
| void  | SetXYZT (Double_t x, Double_t y, Double_t z, Double_t t) | 
|   | 
| void  | SetY (Double_t a) | 
|   | 
| void  | SetZ (Double_t a) | 
|   | 
| void  | Streamer (TBuffer &) override | 
|   | Stream an object of class TObject.  
  | 
|   | 
| void  | StreamerNVirtual (TBuffer &ClassDef_StreamerNVirtual_b) | 
|   | 
| Double_t  | T () const | 
|   | 
| Double_t  | Theta () const | 
|   | 
| TLorentzVector &  | Transform (const TLorentzRotation &) | 
|   | 
| TLorentzVector &  | Transform (const TRotation &) | 
|   | 
| TVector3  | Vect () const | 
|   | 
| Double_t  | X () const | 
|   | 
| Double_t  | Y () const | 
|   | 
| Double_t  | Z () const | 
|   | 
|   | TObject () | 
|   | TObject constructor.  
  | 
|   | 
|   | TObject (const TObject &object) | 
|   | TObject copy ctor.  
  | 
|   | 
| virtual  | ~TObject () | 
|   | TObject destructor.  
  | 
|   | 
| void  | AbstractMethod (const char *method) const | 
|   | Use this method to implement an "abstract" method that you don't want to leave purely abstract.  
  | 
|   | 
| virtual void  | AppendPad (Option_t *option="") | 
|   | Append graphics object to current pad.  
  | 
|   | 
| virtual void  | Browse (TBrowser *b) | 
|   | Browse object. May be overridden for another default action.  
  | 
|   | 
| ULong_t  | CheckedHash () | 
|   | Check and record whether this class has a consistent Hash/RecursiveRemove setup (*) and then return the regular Hash value for this object.  
  | 
|   | 
| virtual const char *  | ClassName () const | 
|   | Returns name of class to which the object belongs.  
  | 
|   | 
| virtual void  | Clear (Option_t *="") | 
|   | 
| virtual TObject *  | Clone (const char *newname="") const | 
|   | Make a clone of an object using the Streamer facility.  
  | 
|   | 
| virtual Int_t  | Compare (const TObject *obj) const | 
|   | Compare abstract method.  
  | 
|   | 
| virtual void  | Copy (TObject &object) const | 
|   | Copy this to obj.  
  | 
|   | 
| virtual void  | Delete (Option_t *option="") | 
|   | Delete this object.  
  | 
|   | 
| virtual Int_t  | DistancetoPrimitive (Int_t px, Int_t py) | 
|   | Computes distance from point (px,py) to the object.  
  | 
|   | 
| virtual void  | Draw (Option_t *option="") | 
|   | Default Draw method for all objects.  
  | 
|   | 
| virtual void  | DrawClass () const | 
|   | Draw class inheritance tree of the class to which this object belongs.  
  | 
|   | 
| virtual TObject *  | DrawClone (Option_t *option="") const | 
|   | Draw a clone of this object in the current selected pad with: gROOT->SetSelectedPad(c1).  
  | 
|   | 
| virtual void  | Dump () const | 
|   | Dump contents of object on stdout.  
  | 
|   | 
| virtual void  | Error (const char *method, const char *msgfmt,...) const | 
|   | Issue error message.  
  | 
|   | 
| virtual void  | Execute (const char *method, const char *params, Int_t *error=nullptr) | 
|   | Execute method on this object with the given parameter string, e.g.  
  | 
|   | 
| virtual void  | Execute (TMethod *method, TObjArray *params, Int_t *error=nullptr) | 
|   | Execute method on this object with parameters stored in the TObjArray.  
  | 
|   | 
| virtual void  | ExecuteEvent (Int_t event, Int_t px, Int_t py) | 
|   | Execute action corresponding to an event at (px,py).  
  | 
|   | 
| virtual void  | Fatal (const char *method, const char *msgfmt,...) const | 
|   | Issue fatal error message.  
  | 
|   | 
| virtual TObject *  | FindObject (const char *name) const | 
|   | Must be redefined in derived classes.  
  | 
|   | 
| virtual TObject *  | FindObject (const TObject *obj) const | 
|   | Must be redefined in derived classes.  
  | 
|   | 
| virtual Option_t *  | GetDrawOption () const | 
|   | Get option used by the graphics system to draw this object.  
  | 
|   | 
| virtual const char *  | GetIconName () const | 
|   | Returns mime type name of object.  
  | 
|   | 
| virtual const char *  | GetName () const | 
|   | Returns name of object.  
  | 
|   | 
| virtual char *  | GetObjectInfo (Int_t px, Int_t py) const | 
|   | Returns string containing info about the object at position (px,py).  
  | 
|   | 
| virtual Option_t *  | GetOption () const | 
|   | 
| virtual const char *  | GetTitle () const | 
|   | Returns title of object.  
  | 
|   | 
| virtual UInt_t  | GetUniqueID () const | 
|   | Return the unique object id.  
  | 
|   | 
| virtual Bool_t  | HandleTimer (TTimer *timer) | 
|   | Execute action in response of a timer timing out.  
  | 
|   | 
| virtual ULong_t  | Hash () const | 
|   | Return hash value for this object.  
  | 
|   | 
| Bool_t  | HasInconsistentHash () const | 
|   | Return true is the type of this object is known to have an inconsistent setup for Hash and RecursiveRemove (i.e.  
  | 
|   | 
| virtual void  | Info (const char *method, const char *msgfmt,...) const | 
|   | Issue info message.  
  | 
|   | 
| virtual Bool_t  | InheritsFrom (const char *classname) const | 
|   | Returns kTRUE if object inherits from class "classname".  
  | 
|   | 
| virtual Bool_t  | InheritsFrom (const TClass *cl) const | 
|   | Returns kTRUE if object inherits from TClass cl.  
  | 
|   | 
| virtual void  | Inspect () const | 
|   | Dump contents of this object in a graphics canvas.  
  | 
|   | 
| void  | InvertBit (UInt_t f) | 
|   | 
| Bool_t  | IsDestructed () const | 
|   | IsDestructed.  
  | 
|   | 
| virtual Bool_t  | IsEqual (const TObject *obj) const | 
|   | Default equal comparison (objects are equal if they have the same address in memory).  
  | 
|   | 
| virtual Bool_t  | IsFolder () const | 
|   | Returns kTRUE in case object contains browsable objects (like containers or lists of other objects).  
  | 
|   | 
| R__ALWAYS_INLINE Bool_t  | IsOnHeap () const | 
|   | 
| virtual Bool_t  | IsSortable () const | 
|   | 
| R__ALWAYS_INLINE Bool_t  | IsZombie () const | 
|   | 
| virtual void  | ls (Option_t *option="") const | 
|   | The ls function lists the contents of a class on stdout.  
  | 
|   | 
| void  | MayNotUse (const char *method) const | 
|   | Use this method to signal that a method (defined in a base class) may not be called in a derived class (in principle against good design since a child class should not provide less functionality than its parent, however, sometimes it is necessary).  
  | 
|   | 
| virtual Bool_t  | Notify () | 
|   | This method must be overridden to handle object notification (the base implementation is no-op).  
  | 
|   | 
| void  | Obsolete (const char *method, const char *asOfVers, const char *removedFromVers) const | 
|   | Use this method to declare a method obsolete.  
  | 
|   | 
| void  | operator delete (void *, size_t) | 
|   | Operator delete for sized deallocation.  
  | 
|   | 
| void  | operator delete (void *ptr) | 
|   | Operator delete.  
  | 
|   | 
| void  | operator delete (void *ptr, void *vp) | 
|   | Only called by placement new when throwing an exception.  
  | 
|   | 
| void  | operator delete[] (void *, size_t) | 
|   | Operator delete [] for sized deallocation.  
  | 
|   | 
| void  | operator delete[] (void *ptr) | 
|   | Operator delete [].  
  | 
|   | 
| void  | operator delete[] (void *ptr, void *vp) | 
|   | Only called by placement new[] when throwing an exception.  
  | 
|   | 
| void *  | operator new (size_t sz) | 
|   | 
| void *  | operator new (size_t sz, void *vp) | 
|   | 
| void *  | operator new[] (size_t sz) | 
|   | 
| void *  | operator new[] (size_t sz, void *vp) | 
|   | 
| TObject &  | operator= (const TObject &rhs) | 
|   | TObject assignment operator.  
  | 
|   | 
| virtual void  | Paint (Option_t *option="") | 
|   | This method must be overridden if a class wants to paint itself.  
  | 
|   | 
| virtual void  | Pop () | 
|   | Pop on object drawn in a pad to the top of the display list.  
  | 
|   | 
| virtual Int_t  | Read (const char *name) | 
|   | Read contents of object with specified name from the current directory.  
  | 
|   | 
| virtual void  | RecursiveRemove (TObject *obj) | 
|   | Recursively remove this object from a list.  
  | 
|   | 
| void  | ResetBit (UInt_t f) | 
|   | 
| virtual void  | SaveAs (const char *filename="", Option_t *option="") const | 
|   | Save this object in the file specified by filename.  
  | 
|   | 
| virtual void  | SavePrimitive (std::ostream &out, Option_t *option="") | 
|   | Save a primitive as a C++ statement(s) on output stream "out".  
  | 
|   | 
| void  | SetBit (UInt_t f) | 
|   | 
| void  | SetBit (UInt_t f, Bool_t set) | 
|   | Set or unset the user status bits as specified in f.  
  | 
|   | 
| virtual void  | SetDrawOption (Option_t *option="") | 
|   | Set drawing option for object.  
  | 
|   | 
| virtual void  | SetUniqueID (UInt_t uid) | 
|   | Set the unique object id.  
  | 
|   | 
| void  | StreamerNVirtual (TBuffer &ClassDef_StreamerNVirtual_b) | 
|   | 
| virtual void  | SysError (const char *method, const char *msgfmt,...) const | 
|   | Issue system error message.  
  | 
|   | 
| R__ALWAYS_INLINE Bool_t  | TestBit (UInt_t f) const | 
|   | 
| Int_t  | TestBits (UInt_t f) const | 
|   | 
| virtual void  | UseCurrentStyle () | 
|   | Set current style settings in this object This function is called when either TCanvas::UseCurrentStyle or TROOT::ForceStyle have been invoked.  
  | 
|   | 
| virtual void  | Warning (const char *method, const char *msgfmt,...) const | 
|   | Issue warning message.  
  | 
|   | 
| virtual Int_t  | Write (const char *name=nullptr, Int_t option=0, Int_t bufsize=0) | 
|   | Write this object to the current directory.  
  | 
|   | 
| virtual Int_t  | Write (const char *name=nullptr, Int_t option=0, Int_t bufsize=0) const | 
|   | Write this object to the current directory.  
  | 
|   |