Abstract base class that represents a two-two scattering reaction. More...

#include <Reaction.hh>

Inheritance diagram for marley::Reaction:

Public Types
enum	ProcessType { NeutrinoCC = 0 , AntiNeutrinoCC = 1 , NC = 2 , NuElectronElastic = 3 }
	Enumerated type describing the kind of scattering process represented by a Reaction. More...

Public Member Functions
virtual marley::TargetAtom	atomic_target () const =0
	Returns the target atom involved in this reaction. More...

virtual marley::Event	create_event (int pdg_a, double KEa, marley::Generator &gen) const =0
	Create an event object for this reaction. More...

virtual double	diff_xs (int pdg_a, double KEa, double cos_theta_c_cm) const =0
	Differential cross section \(d\sigma/d\cos\theta_{c}^{\mathrm{CM}}\) (MeV^-2) More...

const std::string &	get_description () const
	Get a string that contains the formula for this reaction.

int	pdg_a () const
	Get the projectile PDG code.

int	pdg_b () const
	Get the target PDG code.

ProcessType	process_type () const
	Get the process type for this reaction.

virtual double	threshold_kinetic_energy () const =0
	Get the minimum lab-frame kinetic energy (MeV) of the projectile that allows this reaction to proceed via a transition to the residue's ground state.

virtual double	total_xs (int pdg_a, double KEa) const =0
	Compute the reaction's total cross section (MeV^-2) More...

Static Public Member Functions
static int	get_ejectile_pdg (int pdg_a, ProcessType proc_type)

static std::vector< std::unique_ptr< Reaction > >	load_from_file (const std::string &filename, marley::StructureDatabase &db)

static std::string	proc_type_to_string (const ProcessType &pt)

Protected Member Functions
virtual marley::Event	make_event_object (double KEa, double pc_cm, double cos_theta_c_cm, double phi_c_cm, double Ec_cm, double Ed_cm, double E_level, int twoJ, const marley::Parity &P) const
	Helper function that makes an event object. More...

void	two_two_scatter (double KEa, double &s, double &Ec_cm, double &pc_cm, double &Ed_cm) const
	Helper function that handles CM frame kinematics for the reaction. More...

Static Protected Member Functions
static const std::vector< int > &	get_projectiles (ProcessType proc_type)

Protected Attributes
std::string	description_
	String that contains a formula describing the reaction.

double	ma_
	Projectile mass (MeV)

double	mb_
	Target mass (MeV)

double	mc_
	Ejectile mass (MeV)

double	md_
	Residue mass (MeV)

int	pdg_a_
	PDG code for the projectile.

int	pdg_b_
	PDG code for the target.

int	pdg_c_
	PDG code for the ejectile.

int	pdg_d_
	PDG code for the residue.

ProcessType	process_type_
	Type of scattering process (CC, NC) represented by this reaction.

Detailed Description

Abstract base class that represents a two-two scattering reaction.

This class models a reaction of the form a + b → c + d. The projectile (particle a) is taken to have lab-frame kinetic energy KEa and to be traveling toward the target along the positive z direction. The target (particle b) is taken to be at rest in the lab frame.

Todo:: Add check that projectile kinetic energy KEa >= 0. for all relevant member functions of Reaction and NuclearReaction

Member Enumeration Documentation

◆ ProcessType

enum marley::Reaction::ProcessType

Enumerated type describing the kind of scattering process represented by a Reaction.

Enumerator
NeutrinoCC	Nuclear matrix elements contain \( t_{-} \).
AntiNeutrinoCC	Nuclear matrix elements contain \( t_{+} \).
NC	Nuclear matrix elements contain \( t_{3} \).
NuElectronElastic	Neutrino-electron elastic scattering.

Member Function Documentation

◆ atomic_target()

virtual marley::TargetAtom marley::Reaction::atomic_target ( ) const

pure virtual

Returns the target atom involved in this reaction.

For nuclear reactions, this is identical to the pdg_b_ member variable. For electron reactions, it is distinct (since particle b is the initial struck electron).

Implemented in marley::NuclearReaction, and marley::ElectronReaction.

◆ create_event()

virtual marley::Event marley::Reaction::create_event	(	int	pdg_a,
		double	KEa,
		marley::Generator &	gen
	)		const

pure virtual

Create an event object for this reaction.

Parameters

pdg_a	PDG code for the incident projectile
KEa	Lab-frame kinetic energy of the projectile
gen	Reference to the Generator to use for random sampling

Note: Functions that override create_event() should throw an Error if pdg_a != pdg_a_.

Implemented in marley::NuclearReaction, and marley::ElectronReaction.

◆ diff_xs()

virtual double marley::Reaction::diff_xs	(	int	pdg_a,
		double	KEa,
		double	cos_theta_c_cm
	)		const

pure virtual

Differential cross section \(d\sigma/d\cos\theta_{c}^{\mathrm{CM}}\) (MeV^-2)

Parameters

pdg_a	PDG code for the projectile
KEa	Lab-frame kinetic energy (MeV) of the projectile
cos_theta_c_cm	CM frame scattering cosine of the ejectile

Note: Functions that override diff_xs() should always return zero if pdg_a != pdg_a_.

Implemented in marley::NuclearReaction, and marley::ElectronReaction.

◆ get_ejectile_pdg()

int marley::Reaction::get_ejectile_pdg	(	int	pdg_a,
		ProcessType	proc_type
	)

static

Function that returns the ejectile PDG code given the projectile PDG code and the ProcessType

◆ get_projectiles()

const std::vector< int > & marley::Reaction::get_projectiles ( ProcessType proc_type )

staticprotected

Returns a vector of PDG codes for projectiles that participate in a particular ProcessType

◆ load_from_file()

std::vector< std::unique_ptr< marley::Reaction > > marley::Reaction::load_from_file	(	const std::string &	filename,
		marley::StructureDatabase &	db
	)

static

Factory method called by JSONConfig to build Reaction objects given a file with matrix element data

Todo:: Add error handling for parsing problems

Todo:: This can be done more cleanly via iss = std::istringstream( line ); However, GCC 4 does not include the move constructor for string streams. This was fixed for GCC 5. Change this line after MARLEY drops support for GCC < 5. See https://stackoverflow.com/a/27152585 and https://stackoverflow.com/q/7623650 for more details.

Todo:: Consider implementing a sorting procedure rather than strictly enforcing that energies must be given in ascending order.

◆ make_event_object()

marley::Event marley::Reaction::make_event_object	(	double	KEa,
		double	pc_cm,
		double	cos_theta_c_cm,
		double	phi_c_cm,
		double	Ec_cm,
		double	Ed_cm,
		double	E_level,
		int	twoJ,
		const marley::Parity &	P
	)		const

protectedvirtual

Helper function that makes an event object.

This function should be called by marley::Reaction::create_event() after CM frame scattering angles have been sampled for the ejectile. For reactions where the residue may be left in an excited state, the excitation energy should be recorded by supplying it as the final argument.

Parameters

KEa	Lab-frame kinetic energy (MeV) of the projectile
pc_cm	Ejectile 3-momentum magnitude (MeV) in the CM frame
cos_theta_c_cm	Cosine of ejectile's CM frame polar angle
phi_c_cm	Ejectile's CM frame azimuthal angle (radians)
Ec_cm	Ejectile total energy (MeV) in the CM frame
Ed_cm	Residue total energy (MeV) in the CM frame
E_level	Residue excitation energy (MeV)
twoJ	Two times the residue spin
P	Intrinsic parity of the residue

Reimplemented in marley::NuclearReaction.

◆ total_xs()

virtual double marley::Reaction::total_xs	(	int	pdg_a,
		double	KEa
	)		const

pure virtual

Compute the reaction's total cross section (MeV^-2)

Parameters

pdg_a	Projectile's PDG code
KEa	Lab-frame kinetic energy of the incident projectile

Returns: Reaction total cross section (MeV^-2)

Note: Functions that override total_xs() should always return zero if pdg_a != pdg_a_.

Implemented in marley::NuclearReaction, and marley::ElectronReaction.

◆ two_two_scatter()

void marley::Reaction::two_two_scatter	(	double	KEa,
		double &	s,
		double &	Ec_cm,
		double &	pc_cm,
		double &	Ed_cm
	)		const

protected

Helper function that handles CM frame kinematics for the reaction.

Parameters

	KEa	Lab-frame kinetic energy (MeV) of the projectile
[out]	s	Mandelstam s (MeV²)
[out]	Ec_cm	Ejectile total energy (MeV) in the CM frame
[out]	pc_cm	Ejectile 3-momentum magnitude (MeV) in the CM frame
[out]	Ed_cm	Residue total energy (MeV) in the CM frame

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

/Users/gardiner/marley/include/marley/Reaction.hh
/Users/gardiner/marley/src/Reaction.cc

Public Types

Public Member Functions

Static Public Member Functions

Protected Member Functions

Static Protected Member Functions

Protected Attributes

Detailed Description

Member Enumeration Documentation

◆ ProcessType

Member Function Documentation

◆ atomic_target()

◆ create_event()

◆ diff_xs()

◆ get_ejectile_pdg()

◆ get_projectiles()

◆ load_from_file()

◆ make_event_object()

◆ total_xs()

◆ two_two_scatter()