Hi Adam,
although there are uncertainties given in Friedrich/Walcher's paper
(=diagonal elements of the covariance matrix), one can expect that there
are correlations between the parameters (off-diagonal elements) leading
to correlated errors for the parameterization.
In order to really understand what's going here I think it is unavoidable
to take the effort and reproduce the fits, parameters, and their errors
on our own.
Regards,
Michael
On Thu, 31 Aug 2006, Adam Jon DeGrush wrote:
> Hi,
>
> Attached is a plot of what I showed in yesterday's meeting with the Friedrich
> and Walcher curve corrected. Since part of our discussion centered around the
> sizable error in the term corresponding to the location of the bump in GEp, I
> added/subtracted this error to generate two addtional curves. The curve with
> a positive uGEp/GMp ratio in the region ~0.3 GeV^2 is from is with it error
> added, the one that continuously falls off is from the error subtracted.
>
> Regards,
> Adam
>
>
>
>
> On Wed, 30 Aug 2006, Michael Kohl wrote:
>
>> Hi,
>>
>> below are the minutes of today's analysis meeting.
>> The next meeting will be on Wednesday September 6, 2006 at 13:30 at Bates.
>>
>> Minutes:
>>
>> -Status ffr paper
>> +Text has been reviewed.
>> +Figures still being updated, asymmetry plot has been updated.
>> +Chris showing plots of GE and GM. World data should really be
>> original published values for GE and GM from experiments that have
>> really performed Rosenbluth separation on actual measurements (not
>> global fit of other data)
>> +Some authors combine their cross section measurements with existing
>> measurements to perform Rosenbluth separation. For this letter,
>> really only experiments from which a single-expperiment extraction is
>> possible should be plotted.
>> +Yet another discussion on how to extract the form factors GE and GM
>> from the BLAST ratio measurement combined with previous cross
>> section data. Fit versus equation solving. Discussion about nature
>> of cross section error when using parameterization, statistical
>> versus systematic. Although the error of the cross section has
>> a statistical and systematic component, for the purpose of using it
>> with the the BLAST ratio measurement to deduce the separate form
>> factors from solving the equations, the character of the total cross
>> section error becomes systematic (no fitting involved). However, in a
>> fit method where GE and GM result from a fit to the ratio and the cross
>> section values, it only works if the cross section error is treated as
>> point-by-point statistically independent and statistical in its nature.
>> And this exactly causes problems here when using a parametrization
>> because the statistical fluctuation is replaced by an error band.
>> +Will sort things out in offline phone meeting tomorrow at 4pm. Will
>> use the Bates conference line +1-866-867-8301, passcode 4073393
>>
>> -d(e,e'p)
>> +hPz still Q2 dependent (~10% from lowest to highest bin). Possible
>> origins: Diluted data sample (->check cuts); Resolution effects
>> (->study effect of convoluting angles and momenta with finite
>> resolution on asymmetry by varying resolution); or polarization
>> profile along z corresponding to Q2 profile through correlation of
>> z and Q2 (unlikely)
>> +need to compare asymmetries and hPz vs z with MC with and without
>> accounting for spin angle profile. Remaining variation of hPz with z
>> could be due to polarization profile.
>> +proton ff ratio from quasielastic d(e,e'p) at low pmiss (see plot in
>> meeting directory) from super ratio. Ratio data from deuterium
>> slightly below hydrogen data.
>> +Friedrich/Walcher parameterization showing bump even for the ratio,
>> in fact parameter Q_b for the location of bump is much smaller for GEp
>> (0.07) than for GMp (0.35), therefore bumps in GEp and GMp seem not to
>> cancel. However, Fig.3 in F.-W.'s paper shows bump at 0.2-0.3 GeV for
>> all form factors. Something wrong in the Friedrich/Walcher paper? One
>> should verify the fit to the data, like Chris did for Arrington's
>> parameterization.
>>
>> -Comparison of MC for different radiative generators
>> +3 radiative generators available: Mascarad-dgen (Vitaliy), pionmc
>> (Aki) and ElRadGen (Tavi+Sasha)
>> +still bugs in implementation of ElRadGen, need more time
>> +ElRadGen still unpolarize only
>> +need to compare W spectra at generator level
>>
>>
>> Best regards,
>>
>> Michael
>>
>>
>>
>> +-------------------------------------+--------------------------+
>> | Office: | Home: |
>> |-------------------------------------|--------------------------|
>> | Dr. Michael Kohl | Michael Kohl |
>> | Laboratory for Nuclear Science | 5 Ibbetson Street |
>> | MIT-Bates Linear Accelerator Center | Somerville, MA 02143 |
>> | Middleton, MA 01949 | U.S.A. |
>> | U.S.A. | |
>> | - - - - - - - - - - - - | - - - - - - - - -|
>> | Email: kohlm@mit.edu | K.Michael.Kohl@gmx.de |
>> | Work: +1-617-253-9207 | Home: +1-617-629-3147 |
>> | Fax: +1-617-253-9599 | Mobile: +1-978-580-4190 |
>> | http://blast.lns.mit.edu | |
>> +-------------------------------------+--------------------------+
>>
>
+-------------------------------------+--------------------------+
| Office: | Home: |
|-------------------------------------|--------------------------|
| Dr. Michael Kohl | Michael Kohl |
| Laboratory for Nuclear Science | 5 Ibbetson Street |
| MIT-Bates Linear Accelerator Center | Somerville, MA 02143 |
| Middleton, MA 01949 | U.S.A. |
| U.S.A. | |
| - - - - - - - - - - - - | - - - - - - - - -|
| Email: kohlm@mit.edu | K.Michael.Kohl@gmx.de |
| Work: +1-617-253-9207 | Home: +1-617-629-3147 |
| Fax: +1-617-253-9599 | Mobile: +1-978-580-4190 |
| http://blast.lns.mit.edu | |
+-------------------------------------+--------------------------+
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