Weekly Minutes 2008-03-21
From PrimExWiki
Primex Meeting Friday March 21, 2008
present in person or phone: Mark, Ashot, Liping, Dustin, Rory, Dan, Lyang, Ilia, Mahbub, Aron.
Started with a discussion of HallD/Gluex meeting Liping, Ashot, and Jose gave Primex related presentations. Liping mentioned the usefulness of a high energy beam with a precision photon detector. Some examples are eta-> pi0 + 2 gamma, a higher order chiral process and eta-> 2 pi0 which is CP violating. Ashot discussed the strict Hall D schedule. They are closing in on a final design and if Primex wants to influence the specifications for high resolution small angle detection and beam line design. There is an important May meeting. Ashot will write a draft memorandum about this and circulate them. Aron raised the issue of our finishing the pi0 lifetime analysis by the April 4 collaboration meeting and the APS meeting the next week.
An important Hall B meeting will be held with Volker et al. on March 28 to discuss the running schedule for the remainder of the 6 GeV running time. It is important for Primex to get into the schedule with high priority. There is a lot of work to do for Primex to run.
Dustin gave his a presentation of his current results based on the recent report by him and Aron. They noted that there was a clerical error in Table 4 which gives the current results for the width. They are planning to send out a corrected version as soon as it is checked. Dustin reviewed his methodology and the new results in the report. There were several heated discussions. One had to do with the results for the phase angle and the fact that the empirical values for Pb and C were very different. Ashot, quoting Sergey, stated that it was expected that these phases should be close, not equal. Aron said that he was not convinced that this should be the case since the form factors of C and Pb differed by a great deal due to their different sizes and the large difference in the final state nteractions of the outgoing pi0. Ilya noted that the shapes of the omega -> pi0 incoherent and interference contributions are similar. Aron wondered if this might be one reason that the empirical value of phi in C and Pb are different. Ilya also pointed out that Sergey has told him that if the theoretical phases are used for the nuclear coherent form factors, that an empirical phase still has to be added.
Another "hot" issue was the question of the model error in C due to the different shapes of the incoherent calculations being used by Dustin. It was agreed that these need to be brought up to date by use of the latest calculations, and Dustin agreed to make this his first priority. It remains to be seen if the model dependence in C still will persist with the latest calculations, and whether the present insensitivity to the models will remain in Pb.
Finally we decided to have the collaboration meeting April 4 and possibly April 5. At that time we need to have short reports from all of the independent analysis efforts so that we can combine them to a result that we believe is within one sigma of the final result, which we should submit for publication within ~ 3 months (July). Ashot will send the details to the collaboration. Aron suggested that it would be good if the principals make every effort to attend in person since this is a critical meeting.
