https://indico.ihep.ac.cn//event/8183/

First,Amit introduced Observation of the Z → ψl+l− Decay in pp Collisions. Next, he answered other’s questions.

Kai: This paper only shown the invariant mass distributions for the psi muon pairs and psi lepton pairs, but they do not show plots for the other leptons. how to get the conclusion that the other leptons from Z, not from other intermediate states from Z?

Answer: Because of the short life-time of the tau particle, it promptly decays once produced. Hence, it is very difficult to construct Z boson decay with tau lepton than other leptons such as electrons and muons.

Yuzhen: Why the author can get sin2(ϴ23) and ∆(m32)2 from the observed number of e neutrino and anti-e neutrino?

Answer: “Fits to determine either one or two of the oscillation parameters are performed, while the other parameters are marginalized”.Sinθ13 is fixed for this fitting, though I could clearly confirm that the δCP is fixed, (or less effect ?)

Xin: Based on the Fig.1 Feynman diagram, how to derive the gamma *–V transition strength from the measured V → l+l− electromagnetic decays?

Answer: It’s a theoretical question and I can’t give this answer for now. I will have to read more about this.

Yuhang: The probability density function (pdf) of signal is a sum of four terms, each of which is a yield parameter multiplying a component pdf. How to use the four terms account for four different backgrounds?

Answer: The four terms account for the z->psil+l- signal and the backgrounds from Z->l+l- accompanied by nonresonant mu+mu-, nonresonant Jpsil+l-, abd nonresonant mu+mu-l+l-. I didn’t understand too?

Shan: In this sentence: the experimental efficiencies to reconstruct events within the fiducial phase space are determined from simulation; combined with the trigger efficiencies given above they are 81%,80%,81%. Why thest efficiencies are so high?

Answer: As far as I think for these high efficiencies because they have a seperate muon chamber in CMS. Like in BESIII we have muan detection chamber at the outer surface of the detector. So, muons can be detected at both the places.

Suyu: Why is J/psi required from psi(2S)?

Answer: Maybe we can’t distinguish between J/psi and psi(2S).

Ryuta: How we can interpret the obtained value R (=0.67+-0.18+- 0.05) itself ?

Answer: I can not say you more about these limits for the branching fractions as I need to know more about these techniques.

Next,Ryuta introduced the topic around plasma acceleration. The main content contained gradient of RF cavity、advanced WAKEfield Experiment、steps toward the electron acceleration and the comment.

Finally, Xin introduced the motivation about next JC paper.