[Clas12_verystrange] confusion about the resolution of Xi's and Omega's and FT

[Derek Glazier]

Hi Lei,
   Yes the resolution was in. I attach a plot showing the spectra with 
and without FT resolution, the width is 17 MeV without realistic FT 
resolution, compared to 30 MeV with.  Iguess as the momenta of the 
measured particles will be less in the Omega case, the absolute missing 
mass resolution can be smaller.
Cheers
Derek

On 05/15/12 18:13, Lei Guo wrote:
> Hi, Derek,
>
> We have a bit of confusion about the resolution. Was the tagger 
> resolution in your simulation for Omega- (MM(K+K+K0) with a sigma of 
> 30MeV. Michael showed that without the FT resolution in it, the 
> resolution for Xi- (MM of K+K+) and Xi0 (MM of K+Ks) is already on par 
> withe 30MeV. We're hoping that you can clarify that a bit.
>
> Lei
> On Apr 12, 2012, at 11:27 AM, Derek Glazier wrote:
>
>> Hi Lei,
>>
>>  With respect to the comparison with GlueX I guess the big advantage 
>> is Kaon identification. However it may be with the detached vertices 
>> they can get rid of misidentified pions. Probably no one has looked 
>> into it in detail for them yet though and it is probably save to say 
>> their kaon id is not up to it.
>> I attach plots with the Lambda mass constrained. One showing the 
>> comparison between constrained and unconstrained, the width improves 
>> by a factor 6. The other showing the comparison with the Pythia 
>> background. Note I have removed the demand for a detached vertex so 
>> there is some background to compare. It looks promising, although it 
>> looks like more of the background moves under the Omega peak also. 
>> Probably need much higher statistics to say the real effect on the 
>> S/B ratio. Of course with the vertex demand the background is zero 
>> anyway, apart from the 3K detection where kinematic fitting cannot be 
>> used, so I am not sure how much it will really help our already clean 
>> signal.
>> I did not see any real improvement with constraining the K0 mass.
>> I hope this helps.
>> Cheers
>> Derek
>>
>>
>>
>> On 04/10/12 21:32, Lei Guo wrote:
>>> HI, Derek,
>>>
>>> We missed you at the meeting today! :)
>>> Anyway, since we will most likely be asked about this question, and 
>>> the comparison with GLUEX, could you check the change of the Omega- 
>>> resolution if you constrain the four vectors of Lambda (and K0), and 
>>> use the K-Lambda instead for the Omega- mass, in order to see the 
>>> possible improvement in resolution (and s/b ratio) once we have 
>>> kinematic fitting in the experiment?
>>>
>>> Thanks!
>>>
>>> Lei
>>> **************************************
>>>       @
>>>      /    *
>>>     /   ___  ___  Lei Guo _______________________
>>>    L_O_/ ____ Florida International University____/_/
>>>        \   |             Physics Dept., CP 212                       
>>> /  /
>>>     /    \ |             Miami, FL 33199        
>>> /                       /  /
>>>    /  I_/ \  ____ USA _____ /______/__________/  /
>>>   /   /     L                /              /              
>>> /                       /  /
>>>  /   /                       /              /              
>>> /                       /  /
>>> /_/__________/______/______/__________/_/
>>> /_/__________/______/______/__________/_/
>>> 305-348-0234(o)
>>>
>>> **************************************
>>>
>>>
>>>
>>>
>>>
>>
>>
>> -- 
>> The University of Edinburgh is a charitable body, registered in
>> Scotland, with registration number SC005336.
>>
>> <Background4KConsLam.eps><ConstrianLam.eps>
>
> **************************************
>        @
>       /    *
>      /   ___  ___  Lei Guo _______________________
>     L_O_/ ____ Florida International University____/_/
>         \   |             Physics Dept., CP 212                       
> /  /
>      /    \ |             Miami, FL 33199        
> /                       /  /
>     /  I_/ \  ____ USA _____ /______/__________/  /
>    /   /     L                /              /              
> /                       /  /
>   /   /                       /              /              
> /                       /  /
>  /_/__________/______/______/__________/_/
> /_/__________/______/______/__________/_/
> 305-348-0234(o)
>
> **************************************
>
>
>
>
>


-- 
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.

-------------- next part --------------
A non-text attachment was scrubbed...
Name: FTresolution.gif
Type: image/gif
Size: 6650 bytes
Desc: not available
URL: <https://mailman.jlab.org/pipermail/clas12_verystrange/attachments/20120516/5c36578c/attachment-0002.gif>