How to use hepunits - 10 common examples

def test_width_lifetime_conversions():
    assert lifetime_to_width(1.5*ps)/GeV == approx(4.388079676311604e-13)
    assert 1.5*ps * lifetime_to_width(1.5*ps) == hbar
    assert width_to_lifetime(hbar) == 1 * MeV
    #
    with pytest.raises(ValueError):
        lifetime_to_width(-1)
    with pytest.raises(ValueError):
        width_to_lifetime(-1)

def test_width_lifetime_conversions():
    assert lifetime_to_width(1.5*ps)/GeV == approx(4.388079676311604e-13)
    assert 1.5*ps * lifetime_to_width(1.5*ps) == hbar
    assert width_to_lifetime(hbar) == 1 * MeV
    #
    with pytest.raises(ValueError):
        lifetime_to_width(-1)
    with pytest.raises(ValueError):
        width_to_lifetime(-1)

def test_valid_width_lifetime_conversions():
    assert lifetime_to_width(1.5 * ps) / GeV == approx(4.388079676311604e-13)
    assert 1.5 * ps * lifetime_to_width(1.5 * ps) == hbar
    assert width_to_lifetime(hbar) == 1 * MeV

def test_valid_width_lifetime_conversions():
    assert lifetime_to_width(1.5 * ps) / GeV == approx(4.388079676311604e-13)
    assert 1.5 * ps * lifetime_to_width(1.5 * ps) == hbar
    assert width_to_lifetime(hbar) == 1 * MeV

def test_width_lifetime_conversions():
    assert lifetime_to_width(1.5*ps)/GeV == approx(4.388079676311604e-13)
    assert 1.5*ps * lifetime_to_width(1.5*ps) == hbar
    assert width_to_lifetime(hbar) == 1 * MeV
    #
    with pytest.raises(ValueError):
        lifetime_to_width(-1)
    with pytest.raises(ValueError):
        width_to_lifetime(-1)

def test_valid_width_lifetime_conversions():
    assert lifetime_to_width(1.5 * ps) / GeV == approx(4.388079676311604e-13)
    assert 1.5 * ps * lifetime_to_width(1.5 * ps) == hbar
    assert width_to_lifetime(hbar) == 1 * MeV

filter_fn=lambda p: p.pdgid.is_meson
        and p.pdgid.has_strange
        and p.ctau > 1 * meter,
        exclusive_fields=["pdgid", "name"],

    assert 2212 in Particle.findall(lifetime=lambda x: x > 1 * second)

4.33e-10
    >>>
    >>> lifetime_to_width(1.520119980246514*ps)   # result again returned in MeV
    4.33e-10
    >>>
    >>> lifetime_to_width(1.520119980246514*ps)/eV   # result converted to eV
    0.000433
    """

    if tau < 0:
        raise ValueError("Input provided, {0} <= 0!".format(tau))
    elif tau == 0:
        return float("inf")

    # Just need to first make sure that the lifetime is in the standard unit ns
    return hbar / float(tau / ns)

Parameters
    ----------
    Gamma : float > 0
        Particle decay width, typically in MeV (any HEP energy unit is OK).

    Returns
    -------
    Particle lifetime, in the HEP standard time unit ns.
    """

    if Gamma <= 0.:
        raise ValueError( 'Input provided, %s <= 0!'.format(Gamma) )

    # Just need to first make sure that the width is in the standard unit MeV
    return hbar / float(Gamma / MeV)