[Clas_cascades] Minutes 11/3/2010

[Igor Strakovsky]

On Fri, 05 Nov 2010 17:06:58 -0400, Zhiwen Zhao <zwzhao at jlab.org> wrote:

> On 11/05/2010 04:33 PM, Igor Strakovsky wrote:
>> Dear Zhiwen,
>>
>> Thanks that is exactly what I looked for. Can I ask you one more
>> question and to ask to do two more plots?
> sure
>>
>> 3rd column plots are confused me somehow. Theoretically, there is
>> no difference between MM and InvM. So if you plot MM vs. InvM,
>> you have to have a straight line. If you are plotting one vs.
>> different^2, I can expect a parable, not a straight line.
>
> you are right, but with a small range and large width, I think it's hard to 
> tell from straight and parable lines. I can do them in MM vs InvM if 
> necessary

That was my guess

>> Can you please show how 1st column plots depend on collinear cut?

> ok

>> Can you please make two more plots for both K0KM and KPKM say
>> 0.95 and say 0.9 ? what are those numbers?

I would like to compare MM pictures for different cuts on collinearity.
For example, it would be interesting to see such MM distributions
      1) at cos(theta)>0.9
and  2) at cos(theta)>0.95.

It would be also interesting to see how the collinearity cuts
influence the pictures (InvM)vs(MM).

Thanks, Igor

> thanks
> 
> Zhiwen
>>
>> On Fri, 05 Nov 2010 00:02:33 -0400, Zhiwen Zhao <zwzhao at jlab.org> wrote:
>>
>>> The attached files shows the nucleon MM of K0 in PrtK0Km channel and
>>> Kp in PrtKpKm channel.
>>> The MM is in the first column, the InvM of pkm is second, and the
>>> third shows one versus the other
>>> The top row is after nucleon missing mass cut, the bottom row is after
>>> further cut on nucleon missing momentum at 200MeV.
>>> Overall the MM plot has much worse resolution than the InvM plot
>>> around Lambda1520 and the xk0 has worse resolution than xkp
>>>
>>> Those MM plots have no "fermi correction" as I showed in the meeting
>>> because I think the method I used is not good.
>>>
>>> Zhiwen
>>>
>>> On 11/04/2010 01:49 PM, Elton Smith wrote:
>>>>
>>>> resent: Elton, Hovanes, Zhiwen, Stepan
>>>> On the phone: Ralf, Kijun<br>
>>>> Notes by Elton.
>>>>
>>>> == Announcements==
>>>> # No meeting next week due to the collaboration meeting.
>>>>
>>>> == Draft of Phi-- Paper (Hovanes) ==
>>>> # Hovanes uploaded a new version a couple of days ago.
>>>> # Stepan has provided comments. Elton made suggestions to the section on
>>>> upper limits.
>>>> # Kijun has some comments he will send in. Ralf will try to finish
>>>> reading
>>>> the draft today.
>>>> # Ralf: Abstract mentions the Lambda pipi mass spectrum, but it is
>>>> not in
>>>> the paper. We discussed this and concluded that it should be taken
>>>> out of
>>>> the abstract but nevertheless the figure should be added to the
>>>> paper. It
>>>> will make it easier to explain the steps to obtaining Fig. 10.
>>>> # Hovanes suggested changing the title to "upper limits for
>>>> photoproduction cross section of Phi--". No strong opinions were
>>>> offered.
>>>> # Generally, we all need to review the title, abstract and conclusion
>>>> section once the paper is close to final.
>>>>
>>>> == Analysis note for Lambda(1520) (Zhiwen) ==
>>>> # Recoil spectra of MM(K), requested by Igor were shown for both
>>>> MM(K0) in
>>>> gn(p)->pK-K0(p) and also for MM(K+) in gp(n)->pK-K+(n). In both cases
>>>> the
>>>> Fermi momentum blurrs the Lambda peak. The invariant mass of pK- has
>>>> much
>>>> better resolution. In both cases a correction for the Fermi momentum is
>>>> obtained by MM of all three detected particles.
>>>> # Ralf: The Fermi momentum distribution is fairly accurately reproduced,
>>>> so it is surprising that the resolution of the pK- invariant mass is not
>>>> mostly recovered. This was discussed without final conclusion, except
>>>> that
>>>> it is likely that the resolution in missing momentum is poor compared to
>>>> that required for computing the invariant mass. Ralf suggested that the
>>>> generated Fermi momentum be smeared with expected detector resolution to
>>>> see how much it changes the distribution.
>>>> # [http://www.jlab.org/~zwzhao/totalXsection_high.gif Total cross
>>>> section
>>>> for Lambda(1520)] plotted vs energy, shows a large discrepancy in the
>>>> lowers energy point (1.75-2GeV). The estimated cross section is about
>>>> 3+/-1 micro b cross section oompared to about 0.8 microb from other
>>>> data.
>>>> No systematic errors are included, and no bin-centering corrections.
>>>> # Suggestions on what to look for are: check the kinematic cover of the
>>>> bins at high -t. Check bin-centering corrections. Consider
>>>> differences of
>>>> cross section measure with/without phi cut as a measure of the sytematic
>>>> uncertainty.
>>>>
>>>>
>>>> == Next Meeting Nov 18, 8:00 am ==
>>>> # Phi-- Draft of paper (Hovanes)
>>>> # Lambda(1520) update (Zhiwen)
>>>>
>>>>
>>>> Elton Smith
>>>> Jefferson Lab MS 12H5
>>>> 12000 Jefferson Ave
>>>> Suite # 16
>>>> Newport News, VA 23606
>>>> elton at jlab.org
>>>> (757) 269-7625
>>>> (757) 269-6331 fax

Igor Strakovsky, SAID CNS The George Washington University
Tel: 703-726-8344(NV),202-994-4742(FB),Skype: igors1945_2
Fax: 202-994-3001(FB),Emails: igor at va.gwu.edu, igor at jlab.org