**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 generic symbol $T$ always 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 precise positions or motions. 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 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.

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 |