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

[Lei Guo]

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
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>
>
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> <Background4KConsLam.eps><ConstrianLam.eps>

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      /   ___  ___  Lei Guo _______________________
     L_O_/ ____ Florida International University____/_/
         \   |             Physics Dept., CP  
212                       /  /
      /    \ |             Miami, FL  
33199        /                       /  /
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L 
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