(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

so i'm doing some proof-of-concept data analysis this summer and i've never taken a relativistic mechanics class and i'm a bit stuck. i need to figure out if there was a rho^{0}decay to pi^{+}/pi^{-}in some hypothetical 900GeV collision data. If there is, there should be a spike on the histogram i make right around its invariant mass (all the technical stuff and programmy bits i know i've done right).

the information i have:

- momentum of particles

- charge of particles

2. Relevant equations

M_{inv}^{2}= E^{2}-p^{2}

3. The attempt at a solution

i was told to calculate the energy sqrt(m^{2}+p^{2}) for all particles assuming they had the mass of a pion.

then i calculated the invariant mass: M^{2}=(E_{pi+}+ E_{pi-})^{2}- (p_{pi+}+p_{pi-})^{2}

i should get a spike in my histogram at the mass of the rho (about 770 MeV). But i get the spike roughly from 1500-3500MeV.

it seems when looking at my formulas there is some circular derivation going on, but i'm not sure.

if anyone could give me some advice that would be great

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Basic invariant mass calculation

**Physics Forums | Science Articles, Homework Help, Discussion**