TestMuonDecay.cpp

Go to the documentation of this file.

#include "Physics/MuonDecay.h"
#include "Physics/Physics.h"
#include "gtest/gtest.h"
 
#include <cmath>
 
namespace {
 
    TEST(MuonDecayTest, MaxElectronEnergyIsHalfMuonMass) {
        EXPECT_DOUBLE_EQ(Physics::MuonDecay::maxElectronEnergy(), Physics::m_mu / 2.0);
    }
 
    TEST(MuonDecayTest, MinElectronXIsPositiveAndSmall) {
        const double xMin = Physics::MuonDecay::minElectronX();
        EXPECT_GT(xMin, 0.0);
        EXPECT_LT(xMin, 0.02);  // m_e / (m_mu/2) ~ 0.0097
    }
 
    TEST(MuonDecayTest, MichelSpectrumIsNonNegativeInRange) {
        const double xMin      = Physics::MuonDecay::minElectronX();
        constexpr int nSamples = 1000;
        for (int i = 0; i <= nSamples; ++i) {
            const double x = xMin + (1.0 - xMin) * static_cast<double>(i) / nSamples;
            EXPECT_GE(Physics::MuonDecay::michelSpectrum(x), 0.0);
        }
    }
 
    TEST(MuonDecayTest, MichelSpectrumPeaksAtXEqualsOne) {
        const double fPeak = Physics::MuonDecay::michelSpectrum(1.0);
        EXPECT_NEAR(fPeak, Physics::MuonDecay::michelUpperBound(), 1.0e-14);
    }
 
    TEST(MuonDecayTest, MichelSpectrumBelowUpperBound) {
        const double xMin      = Physics::MuonDecay::minElectronX();
        const double upper     = Physics::MuonDecay::michelUpperBound();
        constexpr int nSamples = 10000;
        for (int i = 0; i <= nSamples; ++i) {
            const double x = xMin + (1.0 - xMin) * static_cast<double>(i) / nSamples;
            EXPECT_LE(Physics::MuonDecay::michelSpectrum(x), upper + 1.0e-14);
        }
    }
 
    TEST(MuonDecayTest, MichelSpectrumEndpoints) {
        // f(0) = 0
        EXPECT_DOUBLE_EQ(Physics::MuonDecay::michelSpectrum(0.0), 0.0);
        // f(1) = 2*1*1*(3-2) = 2
        EXPECT_DOUBLE_EQ(Physics::MuonDecay::michelSpectrum(1.0), 2.0);
    }
 
    TEST(MuonDecayTest, MichelUpperBoundIs2) {
        EXPECT_DOUBLE_EQ(Physics::MuonDecay::michelUpperBound(), 2.0);
    }
 
}  // namespace