[Clas_cascades] Minutes 11/3/2010

[Zhiwen Zhao]

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
>
> 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?
>
> 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