[Frost] meeting tomorrow

[Eugene Pasyuk]

It might be also effect of different phase space for protons from these 
two reactions.
Anyhow, it looks like pi0 mass is consistently high in all analyses.
We need to take another look at eloss. May be we still missing something 
there.

-Eugene

Michael Dugger wrote, On 07/23/10 15:29:
>
> Sungkyun,
>
> You might be seeing a "pre-selection" effect. When you define the reaction
> as being "gamma p ->  p pi+ pi-" you have to make some sort of cut. This
> means that only those events that you pre-select as candidates are further
> processed in determining the "missing" mass values for pi+ and pi-.
>
> -Michael
>
> On Fri, 23 Jul 2010, Sungkyun Park wrote:
>
>> Hi Eugene,
>>
>>    I have found the missing mass of pi0 in topology gamma p ->  p X and butanol target.
>>    The pi0 mass 162 MeV
>>
>>     Michael Dugger ->  pi0 (no momentum restriction) = 163 MeV
>>                                 pi0 ( momentum>  600 MeV) = 157 MeV
>>     Hideko Iwamoto ->  pi0 ~ 168 MeV
>>     Jo McAndew     ->  pi0 ~ 176 MeV
>>
>> I also tried to find out the missing mass of pi+ and pi- in topology  gamma p ->  p pi+ pi-
>> The pi+ mass I found is 144 MeV and the pi- mass is 142 MeV.
>> It is very strange why pi0 mass has a big difference with real particle and pi+ and pi- has a very similar value in the same code.
>>
>> Best Wishes
>>
>> Sungkyun Park
>> Florida State University
>>
>>
>>
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