[Clas_cascades] Minutes 11/3/2010

[Alex Kubarovsky]

Dear Zhiwen,

On your plots there is prominent near 1.85 GeV, is it Lamda(1820) or other
Lambda with the mass in this region?

Thanx, Alex.

On Fri, Nov 5, 2010 at 12:02 AM, 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
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>
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