Introduction

Message on HyperNews by Werner

The beam energy shift centers the D0->KPi MBC peak at 1.8645 GeV.  The
real value of the D0 mass is 0.3 MeV higher (according to Amiran's new
measurement).  This means the reported center-of-mass energy is 0.6 MeV
low compared to the "true" value.  Therefore, to get the correct
interaction between the psi(3770) lineshape and the reported Ecm, the
value of M[psi(3770)] used in our lineshape must be 0.6 MeV higher than
the true mass.  In other words, since we take M[psi(3770)]=3774.0 MeV in
our fits, we think the true value is really 3773.4 MeV, which is 1.0 MeV,
or 2 sigma, from the new BES value of 3772.4 +- 0.5 MeV
[hep-ex/0612056].

Another one:

Ha!  That was a test to see if I could trick anyone into believing my
flawed logic....

I think I got it backwards.  If we use M[psi(3770)] = 3774.0 MeV with the
reported Ecm, that's equivalent to using M[psi(3770)] = 3774.6 MeV with
the true Ecm = reported + 0.6 MeV.  This moves us *away* from the BES
value; 4.4 sigma away.

Process

We fit the psi(3770) with mass 3.7724 GeV and width 28.6 MeV1. Compare with our regular fits which has mass of 3.774 GeV and width 27.5 GeV. Since we use the same lineshape parameter for both signal MC and generic MC, the difference arises only in the data. The "diff(%)" is calculated by2:


     /   Yields( test  )         \
    |  --------------------  - 1  |  X 100
     \   Yields(regular)         /
Mode data diff(%)
D0 &rarr K- &pi+ 0.54
D 0&rarr K+ &pi- 0.52
D0 &rarr K- &pi+ &pi0 0.80
D 0&rarr K+ &pi- &pi0 0.83
D0 &rarr K- &pi+ &pi- &pi+ 0.83
D 0&rarr K+ &pi- &pi+ &pi- 0.83
D+ &rarr K- &pi+ &pi+ 0.50
D- &rarr K+ &pi- &pi- 0.51
D+ &rarr K- &pi+ &pi+ &pi0 0.81
D- &rarr K+ &pi- &pi- &pi0 0.80
D+ &rarr KS0 &pi+ 0.65
D- &rarr KS0&pi- 0.59
D+ &rarr KS0 &pi+ &pi0 0.78
D- &rarr KS0&pi- &pi0 0.75
D+ &rarr KS0 &pi+ &pi+ &pi- 0.98
D- &rarr KS0&pi- &pi- &pi+ 1.02
D+ &rarr K+ K- &pi+ 0.92
D- &rarr K- K+ &pi- 0.93

Conclusion

The difference is small, negligible?

1. Fitting plots can be found here.

2. More about this table see here.

[ Front | MyDHad-process | Index ] Updated February 19, 2007