[Clas_cascades] pentaquark search with pK0Km skim

Thu Feb 18 17:46:01 EST 2010

Hi Zhiwen,

On Thu, 18 Feb 2010 14:28:03 -0500, Zhiwen Zhao <zwzhao at jlab.org> wrote:

> Hi,Igor
> 
> Yes, Limiting the missing momentum will not cut all FSI away, but by 
>comparing to simulation, the cut should eliminate a major portion of it.

No way, there is a component which you cannot measure, you have to calculate
There is a chance that this component is small but nobody knows that in 
advance

> For Lambda1520 study, my goal is cross section, so I think the cut may be 
> good enough.

Sorry, I am not sure (see above).  This FSI factor has energy and angular
dependence

> However for theta+ search, the cut may not even be needed because FSI may 
> enhance the theta+ production. my impression is that LEPS didn't correct FSI 
> either as they couldn't do that with two missing particle (PHYSICAL REVIEW C 
> 79, 025210 (2009))

Yes, LEPS calculated nothing and they made some evaluation of the Fermi
which is a fraction of FSI

> Please let me know once you have a Lambda1520 talk or note available.

Please be patient.  I will let you know when it will come

Igor

> Thank you very much.
> 
> Zhiwen
> 
> On 2/18/2010 1:30 PM, Igor Strakovsky wrote:
>> Hi Zhiwen,
>>
>> Unfortunately, your analysis will not allow to accomplish FSI study. It
>> requires theor calculations. They may be small but nobody knows how large
>> they are.
>>
>> Two more small questions for your slides - I did not see your colleniarity
>> cuts. Your #10 shown a selection for M(pi+pi-) only. Then your #24 said
>> about \phi and L(1520) interference but no details
>>
>> Hall A data have been published recently Y. Qiang et al. (JLab Hall A
>> Collaboration), Phys. Rev. C 75, 055208 (2007); arXiv:hep-ex/0609025 and
>> we made analysis addressed to the determination of the L(1520) parameters
>>
>> Igor
>>
>>
>> On Thu, 18 Feb 2010 12:07:19 -0500, Zhiwen Zhao <zwzhao at jlab.org> wrote:
>>
>>> hi, Igor
>>>
>>> The statistics won't allow me to study FSI, so I plan to cut on quasi
>>> free reaction by limiting missing momentum later on.
>>> I didn't know you are doing Lambda1502 in HallA. That's GREAT news.
>>> Can you show me some notes or talks you already have?
>>>
>>> Thank you
>>>
>>> Zhiwen
>>>
>>> On 2/17/2010 9:04 PM, Igor Strakovsky wrote:
>>>> Hi Zhiwen,
>>>>
>>>> On Wed, 17 Feb 2010 16:56:21 -0500, Zhiwen Zhao <zwzhao at jlab.org> wrote:
>>>>
>>>>> Hi,Igor
>>>>>
>>>>> On 2/14/2010 12:45 PM, Igor Strakovsky wrote:
>>>>>> Hi Zhiwen,
>>>>>>
>>>>>> Thank you for your prompt reaction. I would afraid to make a claim
>>>>>> until
>>>>>> to get strong arguments. It sounds that you do not have them yet
>>>>> Exactly, I am not making any claim
>>>>>>
>>>>>> A little bit more below
>>>>>>
>>>>>> On Sat, 13 Feb 2010 22:28:40 -0500, Zhiwen Zhao <zwzhao at jlab.org>
>>>>>> wrote:
>>>>>>
>>>>>>> Hi, Igor
>>>>>>>
>>>>>>> No, I am not sure at this point as the result is just a first look
>>>>>>> into the data, not even qualified as preliminary.
>>>>>>> However these cuts I showed are supposed either to enhance the theta+
>>>>>>> signal or to match LEPS condition.
>>>>>>
>>>>>> As your slides shown that you did not do exact LEPS condition
>>>>> For angle, LEPS has horizontal 20 degree and vertical 10 degree
>>>>> coverage. So far I require theta < 20 degree and it's only for Km, not
>>>>> for all charged particles like LEPS. I will test more cuts.
>>>>> For photon energy, my cut matches their condition 2-2.4GeV
>>>>
>>>> Well, as I said your condition does not fit LEPS configuration well;)
>>>>
>>>>>>> I have looked their Anti-cuts also, no sign of theta+ either.
>>>>>>> Some cuts I didn't show such as photon selection,PID, fiducial,
>>>>>>> vertex, sc dad counter etc, are mostly standard and similar to what
>>>>>>> Hovanes used in his
>>>>>>
>>>>>> As far as you probably know, CLAS has so many standards. It is good to
>>>>>> clarify them
>>>>> Some cuts you can see from Hovanes's analysis note
>>>>> http://clasweb.jlab.org/rungroups/eg3/wiki/index.php/Analysis_review_by_Hadron_Spectroscopy_Working_Group
>>>>>
>>>>>
>>>>> I am in the process of writing Lambda1520 note also.
>>>>>>
>>>>>>> eg3 pentaquark Phi-- upper limit analysis which is currently under
>>>>>>> review.
>>>>>>> The same PK0Km channel is used for Lambda1520 study which is my
>>>>>>> thesis
>>>>>>> topic, I have preliminary cross section now.
>>>>>>
>>>>>> Sorry, I know nothing about your theses and would love to see your
>>>>>> Lambda(1520). Unfortunately, the size of your figures do not allow
>>>>>> to see details
>>>>> Here's a talk I gave for Lambda1520
>>>>> http://clasweb.jlab.org/rungroups/eg3/wiki/images
>>>>> /5/52/ApsApril2010_zwzhao_Lambda1520.pdf
>>>>> I apologize for the figures, I will update them with better ones.
>>>>
>>>> Thank you for your figures, I missed them. It seems to me that our
>>>> coming
>>>> paper addressed to the analysis of the Hall A Lambda(1520)
>>>> electroproduction
>>>> data at small Q2 may be interesting for you. I hope we will submit it in
>>>> 2-3 weeks.
>>>>
>>>> To be honest, your analysis of the neutron data is a big problem for me
>>>> because you did not take into account FSI
>>>>
>>>>>>> I have MC for the Lambda1520 production, but not PK0Km yet.
>>>>>>
>>>>>> Can you show them, please? What did you use as the generator
>>>>> will do.
>>>>> I use fsgen which is a phase space generator with t-slope=2 as input
>>>>> for my Lambda1520 channel.
>>>>
>>>> OK, thanks. Igor
>>>>
>>>>>>> I will add more stuff on the wiki when the analysis proceeds.
>>>>>>> Any comment from you is greatly appreciated.
>>>>>>
>>>>>> Thanks, I look forward to learn more details from you
>>>>>> Igor
>>>>>>
>>>>>>> Zhiwen
>>>>>>>
>>>>>>>
>>>>>>> On 2/12/2010 1:14 AM, Igor Strakovsky wrote:
>>>>>>>> Hi Zhiwen,
>>>>>>>>
>>>>>>>> How are so sure? You made so many cuts... Can you explain all of
>>>>>>>> them?
>>>>>>>> Can you show any well known resonances? Do you have MC?
>>>>>>>>
>>>>>>>> Igor
>>>>>>>>
>>>>>>>> On Fri, 12 Feb 2010 01:04:37 -0500, Zhiwen Zhao <zwzhao at jlab.org>
>>>>>>>> wrote:
>>>>>>>>
>>>>>>>>> hi, Eg3er
>>>>>>>>>
>>>>>>>>> Here is some updates of the pentaquark search with pK0Km skim
>>>>>>>>> http://clasweb.jlab.org/rungroups/eg3/wiki/index.php/PrtK0Km_theta1530
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> So far, there's no sign of pentaquark.
>>>>>>>>> Any commend is appreciated.
>>>>>>>>>
>>>>>>>>> Zhiwen