Energy resolution of LHC Electromagnetic Calorimeter

So I am trying to get an estimate of the electromagnetic calorimeter resolution at LHCb, and I have found this online:

But I have no idea of what it means.

Can anyone explain what the last part represents?

My signal is a $B_d$ mass with rest mass $m = 5,279.53$ $MeV/c^2$

• BTW -- the tag [accelerator-physics] is for the physics of accelerators, not physics done by taking the beams. Nov 22 '14 at 21:44

The uncertainty in any particular measurement is $\sigma_E$. Resolution for these devices is almost always stated in relative terms as here, but take it like this because it depends on the energy measured.
So just multiply by the energy. That is, express your signal in $\mathrm{GeV}$ and then find \begin{align} \sigma_E = \left(\frac{0.1}{\sqrt{E}} \oplus 0.01\right) E \end{align}
I've not seen this notation before (I'm not a colider guy) but I suspect that the $\oplus$ mean "add in quadrature", so \begin{align} \sigma_E = \sqrt{ \left(\frac{0.1}{\sqrt{E}}\right)^2 + (0.01)^2} E \end{align}
• So would the $E$ here be my signal? The rest energy of the heavy meson? Nov 23 '14 at 15:19
• When you look at a (segmented) calorimeter, you do apply some process to select a bunch of hits which you are treating as belonging together. Then you add up the energy those hits represent and that sum is your $E$. The selection process is important and for a calorimeter in a colider experiment it is unlikely to be "just take it all" the way it might be in a low rate experiment. Nov 23 '14 at 16:31