**thermodynamic temperature**$\, T \sf{(K)} \,$ is defined by

$T \sf{(K)} \ \equiv \ \mathit{T} \sf{(ºC)} + \mathrm{273.15}$

where $\, T \sf{(ºC)} \,$ is the Celsius temperature. In the following discussion, the symbol $T$ refers to the thermodynamic temperature, in units called *kelvins*, noted by (K).

Quarks are indestructible but compound quarks may decay. Their stability is characterized by a number called the *mean-life*. Let particle P be described by its thermodynamic temperature $T$. Definition: The **mean life** of P is

$\tau \equiv k_{\tau} e^{ -T}$

where $e$ is the exponential function and the constant $k_{\tau} = \sf{ 2.6 x 10 }^{\sf{56}}$ seconds. Customarily, if $\sf{P}$ is an atom of hydrogen in its ground-state, then $T=0 \ \sf{(K)}$ and $e^{ 0} = 1$, so this constant $k_{\tau}$ is called the*mean-life of hydrogen*.

^{1}A particle with a negative temperature supposedly has a longer mean-life than hydrogen. But for WikiMechanics, the only particles like this are some quarks and field quanta that are not assigned positions. All models of observed nuclear particles have a positive thermodynamic temperature. Particle stability is also characterized by a number called the

**full width**which is noted by $\varGamma$ and defined as

$\begin{align} \varGamma \equiv \frac{h}{2 \pi \tau} \end{align}$

The total number of any specific type of quark does not vary if ordinary-quarks are swapped with anti-quarks of the same type. And with the assumption of conjugate symmetry, ordinary-quarks and anti-quarks both have the same temperature. So

$\tau ( \sf{P} ) = \tau ( \overline{\sf{P}} ) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \sf{\text{and}} \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \varGamma ( \sf{P} ) = \varGamma ( \overline{\sf{P}} )$

Particles and their associated anti-particles have the same mean-life and full-width.

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Lifetime |

Summary |

Adjective | Definition | |

Thermodynamic Temperature | $T \sf{(K)} \ \equiv \ \mathit{T} \sf{(ºC)} + \mathrm{273.15}$ | 8-4 |

Adjective | Definition | |

Mean Life | $\tau \equiv k_{\tau} e^{ -T}$ | 8-5 |

Adjective | Definition | |

Full Width | $\begin{align} \varGamma \equiv \frac{h}{2 \pi \tau} \end{align}$ | 8-6 |