Comments and questions

email 9oct2017

1.) charged particle multiplicities: we use events under the condition that one and only one positively charged particle and one and only one negatively charged particle and one and only one proton was present, right? and thats not even asking whether the charged pair is pions or electrons. this is ok if we show that higher charged particle multiplicities are negligible. or, even better, we produce a skim that keeps all charged particles.

2.) track efficiency: my understanding is the following: the track efficiency has been evaluated using the momenta after kinematic fit and looping over the tagger photons (?). we should use the new fit (please a reminder, for me, where to find it) because there the pulls are improved, right? and then use the updated track efficiency (please also here reminder where to find).

3.) comparison with simulation: comes after track efficiency. the comparison always has to be looked at for the basic variables, momenta and angles, plus for g12 the z component of the vertex(?). there is no way that this comparison can be ignored or skipped. it already tells you whether you need to modify the event generator. that is the reason why you have to make sure you are looking at signal events from the data. of course one can also look at the comparison on the level of the final result variables but that is additional. typically, one rather shows the reconstruction efficiency as a function of the variables.

4.) efficiency: if you modify the phase space event generator by using a model then you are using a model-dependent efficiency. alternatively, you can modify it in iterations, without using a model. either way, the procedure causes a systematic uncertainty which is what Daniel wanted to investigate.

Regards, Su.