JPHYSICS::JDIS::JDIS_t Class Reference

Auxiliary helper class for kinematics of deep-inelastic muon-nucleon scattering at fixed muon energy. More...

#include <JDIS.hh>

Public Member Functions
	JDIS_t (const double E)
	Constructor. More...
double	getP (const double v) const
	Get probability of given energy fraction. More...
double	getE () const
	Get shower energy. More...

Public Attributes
const double	E
	actual energy [GeV] More...
const double	E2
	maximal energy [GeV] More...

Static Public Attributes
static constexpr double	E0 = 0.144
	minimal energy [GeV] More...
static constexpr double	E1 = 0.35
	breakpoint [GeV] More...
static constexpr double	p0 = 2.0
	spectral index upto breakpoint More...
static constexpr double	p1 = -1.11
	spectral index from breakpoint More...

Private Member Functions
double	getA (const double v, const bool option=true) const
	Integral upto breakpoint. More...
double	getB (const double v, const bool option=true) const
	Integral from breakpoint. More...
double	getb (const double v) const
	Integral from breakpoint without suppression factor. More...

Private Attributes
double	k1
	normalisation constant upto breakpoint More...
double	k2
	normalisation constant from breakpoint More...

Detailed Description

Auxiliary helper class for kinematics of deep-inelastic muon-nucleon scattering at fixed muon energy.

Definition at line 119 of file JDIS.hh.

Constructor & Destructor Documentation

JPHYSICS::JDIS::JDIS_t::JDIS_t ( const double  E )

inline

Constructor.

Parameters

E	muon energy [GeV]

Definition at line 126 of file JDIS.hh.

                             :
        E (E),
        E2(E - MASS_MUON)
      {
        k2 = pow(E1, p0 - p1) / pow(1.0 - E1/E, 2);

        const double A = getA(E1/E, false) - getA(E0/E, false);
        const double B = getB(E2/E, false) - getB(E1/E, false);

        k1 = 1.0 / (A + k2 * B);
      }

Member Function Documentation

double JPHYSICS::JDIS::JDIS_t::getP ( const double  v ) const

inline

Get probability of given energy fraction.

Parameters

v	energy fraction

Returns

probability

Definition at line 145 of file JDIS.hh.

      {
        const double x = E*v;
        const double u = 1.0 - v; 

        if      (x > E2)
          return 0.0;
        else if (x > E1)
          return k1 * k2 * pow(x, p1) * u*u;
        else if (x > E0)
          return k1 *      pow(x, p0);
        else
          return 0.0;
      }

double JPHYSICS::JDIS::JDIS_t::getE ( ) const

inline

Get shower energy.

Returns

shower energy [GeV]

Definition at line 166 of file JDIS.hh.

      {
        const double A = getA(E1/E) - getA(E0/E);
        const double B = getB(E2/E) - getB(E1/E);

        for ( ; ; ) {

          double y = gRandom->Rndm() * (A + B);

          if (y <= A) {

            y += getA(E0/E);
            y /= k1 * pow(E,p0) / (p0 + 1);

            const double v = pow(y, 1.0 / (p0 + 1));

            return E * v;

          } else {

            y -= A;
            y *= (getb(E2/E) - getb(E1/E)) / B;
            y +=  getb(E1/E);
            y /= k1 * k2 * pow(E,p1) / (p1 + 1);
          
            const double v = pow(y, 1.0 / (p1 + 1));
            const double u = 1.0 - v; 

            if (gRandom->Rndm() < u*u) {
              return E * v;
            }
          }
        }
      }

double JPHYSICS::JDIS::JDIS_t::getA ( const double  v, const bool  option = true  ) const

inlineprivate

Integral upto breakpoint.

Parameters

v	energy fraction
option	option (if false, suppress normalisation constant)

Returns

integral

Definition at line 218 of file JDIS.hh.

      {
        return (option ? k1 : 1.0)      * pow(E, p0) * pow(v, p0 + 1) * (1.0 / (p0 + 1));
      }

double JPHYSICS::JDIS::JDIS_t::getB ( const double  v, const bool  option = true  ) const

inlineprivate

Integral from breakpoint.

Parameters

v	energy fraction
option	option (if false, suppress normalisation constant)

Returns

integral

Definition at line 231 of file JDIS.hh.

      {
        return (option ? k1 * k2 : 1.0) * pow(E, p1) * pow(v, p1 + 1) * (1.0 / (p1 + 1)  -
                                                                         2*v / (p1 + 2)  +
                                                                         v*v / (p1 + 3));
      }

double JPHYSICS::JDIS::JDIS_t::getb ( const double  v ) const

inlineprivate

Integral from breakpoint without suppression factor.

Parameters

v	energy fraction

Returns

integral

Definition at line 245 of file JDIS.hh.

      {
        return k1 * k2 * pow(E, p1) * pow(v, p1 + 1) / (p1 + 1);
      }

Member Data Documentation

const double JPHYSICS::JDIS::JDIS_t::E

actual energy [GeV]

Definition at line 201 of file JDIS.hh.

const double JPHYSICS::JDIS::JDIS_t::E2

maximal energy [GeV]

Definition at line 202 of file JDIS.hh.

constexpr double JPHYSICS::JDIS::JDIS_t::E0 = 0.144

static

minimal energy [GeV]

Definition at line 204 of file JDIS.hh.

constexpr double JPHYSICS::JDIS::JDIS_t::E1 = 0.35

static

breakpoint [GeV]

Definition at line 205 of file JDIS.hh.

constexpr double JPHYSICS::JDIS::JDIS_t::p0 = 2.0

static

spectral index upto breakpoint

Definition at line 207 of file JDIS.hh.

constexpr double JPHYSICS::JDIS::JDIS_t::p1 = -1.11

static

spectral index from breakpoint

Definition at line 208 of file JDIS.hh.

double JPHYSICS::JDIS::JDIS_t::k1

private

normalisation constant upto breakpoint

Definition at line 250 of file JDIS.hh.

double JPHYSICS::JDIS::JDIS_t::k2

private

normalisation constant from breakpoint

Definition at line 251 of file JDIS.hh.

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

• JDIS.hh