LCFI Physics Studies Meeting, 18 th October 2005Sonja Hillertp. 0 Using event display for improving Q vtx reconstruction  event display might help to identify possibilities for improving vertex charge reconstruction  wrote routine that puts out events in the xml format needed for the Bristol event display, to be called only for events, in which vertex charge reconstruction gives wrong result  some of the cuts applied in the Bristol event output have been dropped: no track quality cuts all MC vertices are included (there can be more than one ‘tertiary’ in some cases)  with present display, can clearly see jets, tracks and vertices, can rotate and zoom;  however, to identify reconstruction problems, extended functionality is needed: zoom limited and sometimes insufficient directions of axes, and a scale would help would be good to be able to switch to R  and z view

LCFI Physics Studies Meeting, 18 th October 2005Sonja Hillertp. 1 Some ‘features’ (bugs?) of the current display  sometimes switching on/off MC vertices can cause a MC tracks to appear/disappear or ‘flip’ (be drawn at a different angle) – so far only noticed for ‘unseen’ tracks  seems that only two MC vertices are drawn per event, even if more are contained in the input file – might be the same for the reconstructed (but these are harder to find, because they are drawn as ellipsoids that are sometimes very much stretched in one direction)  navigation is sometimes difficult: event seems to rotate very easily, but shifting it in the window is Impossible or difficult to achieve  already at 100 GeV jet energy, jets are so narrow that it is hard to see the details around particle decay points one is interested in – ideally it would be good if one could ‘compress’ the event along the thrust axis to make these features better visible

LCFI Physics Studies Meeting, 18 th October 2005Sonja Hillertp. 2 Suggestions for extensions  would be good, if one could switch on/off tracks from each jet independently, (without restriction to two jets, since for multijet events, this might be needed even more)  only from looking at tracks there is no way to tell, which have been assigned to the B decay chain and which ones have not – a colour code for track assignment is needed; suggest a new tag ‘QvtxAssignment’ with four possible values corresponding to tracks correctly assigned to the B decay chain tracks correctly assigned to the background (IP + other) missed tracks added tracks, each represented by a different colour  Question to Dave B: could one have some optional tags for the above in the XML file? (since the above requests are rather specific, some users might not want to provide this information in their input files)