[Clas12_verystrange] Omega-

[Derek Glazier]

Hi Mike,
   My analysis of the same final state gives quite different results. 
Basically I just weight the number of generated events by the cross 
sections of total hadronic events (130,000nb) to Omega- (0.5nb). i.e I 
use 260,000 times more generated events for the total hadronic 
background, than for Omega-. I simulated 200M pythia events and get a 
signal to background ratio of around 1:10. I attach the plot. I generate 
events tagged by the forward tagger with e- energy range 0.5-6GeV. I do 
not use any PID scheme as such, just assume the particles are identified 
correctly. I also cut on the K0 mass and pi-pi+ coming from the same 
vertex, but I do not care if it is detached from the K+ vertex or not.
   I also attach a similar plot for also detecting the K- where the 
situation is improved and in particular, if a vertex cut is used the 
background is zero.
   I prefer your results however, so will try and see if I can track 
down a bug.
Cheers
Derek


On 02/24/12 17:12, Michael Dugger wrote:
> I have the cross section for the Omega- set to
> (1/10)*crossSection(neutral cascade).
>
> -Michael
>
> On Fri, 24 Feb 2012, andrei afanasev wrote:
>
>> Mike,
>> The signal looks very good. What was the value you used for the production cross section for Omega? Since it is unknown, it makes sense to vary it within realistic estimates that we put in the Omega LOI before.
>> -Andrei
>> -----Original Message-----
>> From: Michael Dugger<dugger at jlab.org>
>> Sender: clas12_verystrange-bounces at jlab.org
>> Date: Fri, 24 Feb 2012 11:32:26
>> To:<clas12_verystrange at jlab.org>
>> Reply-To: clas12_verystrange at jlab.org
>> Subject: [Clas12_verystrange] Omega-
>>
>>
>> Hi,
>>
>> I have generated ~100 million background events and blended them with an
>> Omega- signal, and want to see if the plot I get seems reasonable.
>>
>> The plot OmegaMbranch.gif is attached and shows the relative amount of
>> background to be expected when a K+ K+ and K0 is seen (the K0 is
>> reconstructed from a pi+ pi- pair). I have put in a PID scheme, but do not
>> approximate the Cerenkov counter response. The PID is only from beta and
>> momentum information.
>>
>> Thanks for your time.
>>
>> Take care,
>> Michael
>>
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