Neutron Decay: Questions & Answers

[Dalor]

Hi, I have questions on the neutron decay

What prevent the neutron to decay in udc or udt except mass/energy consideration ?

If we do the assumption that (udc) and (udt) have the same mass than the proton (yes I know, this doesn't make sense) the three decay (p, udc, udt) woulld have the same probability ?

Also this is only energy consideration that prevent the $W$ to decay in $q \bar q$ too?

Thank you

 

[mathman]

A neutron is udd. Your question is confusing.

 

[mfb]

If the heavier quarks would be much lighter we would see them in everyday life, too.

As extreme case: If they would have the same mass we wouldn't consider them as different particle types.

If we do the assumption that (udc) and (udt) have the same mass than the proton (yes I know, this doesn't make sense) the three decay (p, udc, udt) woulld have the same probability ?

No, there is still the CKM matrix. d->u has a higher amplitude than d->c or d->t.

 

[Orodruin]

Also this is only energy consideration that prevent the WWW to decay in q¯qqq¯q \bar q too?

The W does decay to $q\bar q$. However, the final state cannot be a single meson due to energy conservation and the quarks therefore quickly hadronize. Most of the time W decays hadronically.

 

[Dalor]

Oh I was definitely not paying attention !

No, there is still the CKM matrix. d->u has a higher amplitude than d->c or d->t.

Of course my mistake.
(Yes, they would be same particle, it was only for the "thought experiment".)

The W does decay to $q\bar q$. However, the final state cannot be a single meson due to energy conservation and the quarks therefore quickly hadronize. Most of the time W decays hadronically.

Yep I meant the hadronic decay $u \bar d$, $u \bar s$ and so on.

My question came from the $\Lambda^0$, the leptonic decay is suppressed by several order of magnitude. I don't understand why since BR between leptonique and hadronic decay is not so low and it seems a big difference considering only phase space factor, no ? And the other hand in neutron decay there is only the leptonic decay, that was why I ask the kind of meaningless question about "the neutron decay if quark add same mass".

Thank you.