What is the Conversion for Units in Particle Physics?

[ylem]

Hello!

I was wondering if someone could help me with a problem of units!

I'm currently deriving probability equations for neutrino oscillations and I'm stuck with units!

I have: [(mass)^2 * time]/[4*energy] and I want to write it as [1.27 * (mass)^2 * distance]/[Energy] with distance in metres, energy in MeV and the mass in eV^2. I get that I can use the relativist approximation to get from time to distance (taking c and hbar to be 1).

I'm just wondering how you get the 1.27 that allows you to use this conversion? I assume it is [1eV^2 * 1 metre in MeV * (1/MeV)] but I don't know what 1 metre is in MeV. Can someone explain to how determine it?

Also, if anyone could explain how to get seconds in inverse MeV that would be great!

Thanks a lot, Sam

 

[Meir Achuz]

There is a conversion 1=197 MeV-fm.
(you get that from 1=hbar*c.)
Then use 1=3X10^8 m/s.

 

[sir-pinski]

The conversion for units in particle physics can be quite complex, as it often involves combining different physical quantities and constants. In your specific case, the conversion factor of 1.27 comes from the fact that the speed of light in a vacuum, c, can be expressed as 1 meter per inverse second (m/s), and the Planck constant, h, can be expressed as 1 joule second (J*s). Therefore, the conversion factor between time and distance is 1 meter per inverse joule (m/J).

To convert from time to distance, you can use the relativistic approximation, as you mentioned, which states that time and distance are related by the speed of light. In this case, you can use the conversion factor of 1 meter per inverse second (m/s) to convert from time to distance.

For the conversion from seconds to inverse MeV, you can use the fact that 1 eV (electron-volt) is equal to 1.6022 * 10^-19 joules. Therefore, 1 MeV (mega-electron-volt) is equal to 1.6022 * 10^-13 joules. Using this conversion, you can then convert seconds to inverse MeV by dividing by the energy in MeV.

I hope this helps with your unit conversion and good luck with your neutrino oscillation equations!