# Asymmetry in muon energies of public CMS dimuon event data

CMS published for educational purposes (caveat) 100.000 dimuon events:

https://cms-docdb.cern.ch/cgi-bin/PublicDocDB//ShowDocument?docid=11583

As one easily sees, column 4 shows the first muon's energy, column 12 the second's. Although the first energy is not higher in general (the data are not ordered),the distribution of energies is asymmetric. The first muons energy is higher on average, as one can easily see with the following Mathematica code: (download the first file dimuon.csv to your working directory)

SetDirectory["c:\\yourworkingdirectory\"];
qwe = Import["dimuon.csv", "CSV"];

wer = Drop[qwe, 1];    (* select the events labelled "GG"*)

rty = Select[wer, ((#[[1]] == "GG")) &]; ert = Transpose[rty];

energy1 = ert[[4]]; energy2 = ert[[12]];
relationOfEnergies = energy1/(energy1 + energy2);

bcEnergies = BinCounts[relationOfEnergies, {0, 1, .01}];

BarChart[bcEnergies, Ticks -> {Table[i, {i, 0, 100, 10}], Automatic}];


Here is the result ("GG" events oly), the first energy as a fraction of both muon's energies:

Could have a trivial reason, just curiosity...