Re: Joint FVTX/VTX discussion on blind analysis today

["Barbara Jacak" <jacak@skipper.physics.sunysb.edu>]

Dear all,
       I would like to, once again, concur and amplify this request from
Jamie. It is a very important proof-of-principle and first step to quantify
our c/b separation capabilities in p+p collisions using PYTHIA events.
When we last had an email exchange about this, there were technical
difficulties in handling and analyzing the events that precluded addressing
this question. Are those now under control? If so, then this analysis
could take place in parallel with generation of HIJING background
events for Au+Au performance studies. If not, what is still missing?

best regards,
Barbara

On 1/14/09, jamie.nagle@colorado.edu <jamie.nagle@colorado.edu> wrote:
> Hello Sasha and Other Blind-ers,
>
> I had made the suggestion many months ago, but think given the time
> schedule, it might be worth re-visiting.  The suggestion was that the
> blind analysis should start with the proton-proton 200 GeV case.  One can
> just run PYTHIA events and adjust the charm and beauty cross sections (and
> perhaps a slight change in the ratio of different D/B states).  This will
> lead to a much shorter time schedule for a result - since one does not
> need lots of HIJING events with full response, disk space, recon. time,
> etc.
>
> At the time, the assertion was that separating c and b in the
> proton-proton case was easy, and not necessary to test.  I believe there
> are enough concerns that this should be done, and done first - to have a
> result sooner, which then builds confidence.  After that, the full Au-Au
> case can be done. I would appreciate it if this can be discussed and
> decided on.
>
> Also, Bill was explaining how there is often a mis-conception that because
> the D has a c\tau that is ~x3 different than the B c\tau, the DCA
> distributions will be very different.  The problem is that the distance
> the meson travels before decaying is \gamma c \tau.  Thus, if one selects
> a fixed momentum electron or muon (and assume it carries the same momentum
> fraction from the parent), the \gamma is ~x1/3 for the B meson.  Thus the
> \gamma c \tau is quite similiar.  Everything is in the decay kinematics.
>
> I was reading Analysis Note 727 (Eric Vazquez, David Winter), and was
> wondering if someone can post or point to the DCA distributions for
> electrons within |\eta| < 0.35 as a function of pT of the electron from D
> mesons and B mesons (separately).  What I would like to see is the DCA
> assuming an absolutely perfect detector - basically just the distributions
> straight out of PYTHIA for example (no detector response at all).  I make
> the same request for the same distributions for the pseudorapidity
> coverage of the muon arms (fVTX).  It would be good for the electron and
> muon cases to see these plots in fine bins in pT going from pT = 0.0 -
> 10.0 GeV/c.  Presumably at some high enough momentum, the decay product is
> mostly co-linear with the parent.
>
> I realize there are much more advanced studies already under way (and I
> have seen some sub-sample of the plots mentioned above), but believe it
> would help me and others in PHENIX to see the basic kinematics of the
> problem over the full range of momentum.
>
> Sincerely,
>
> Jamie
>
> +--------------------------------------------------------------------------------+
> || James L. Nagle                      EMAIL:  jamie.nagle@colorado.edu
>     ||
> || Associate Professor of Physics      PHONE:  (303) 735 - 3560 (OFFICE)
>     ||
> || University of Colorado at Boulder   PHONE:  (303) 735 - 2996 (LAB)
>     ||
> ||                                     FAX:    (303) 492 - 3352
>     ||
> ||                                     MAIL:   Department of Physics
>     ||
> ||                                             University of Colorado at
> Boulder ||
> ||                                             390 UCB
>     ||
> ||                                             Boulder, CO 80309-0390
>     ||
> ||                                     WEB:
> http://spot.colorado.edu/~naglej  ||
> +---------------------------------------------------------------------------------+
>
>
> On Tue, 13 Jan 2009, Alexandre Lebedev wrote:
>
>> Hi all,
>>
>> As we agreed at today's meeting, I've created a wiki page for
>> the blind analysis challenge in order to collect all relevant information.
>> The page is:
>>
>> https://www.phenix.bnl.gov/WWW/offline/wikioffline/index.php/Blind_Analysis_Challenge_for_FVTX/VTX_Detector_Upgrades
>>
>> You can also access it from the main Phenix offline wiki page (at the
>> very bottom).
>>
>> I would like to encourage everyone to contribute to this web page. Doing
>> this is very easy, and the more information we have there, the easier it
>> will
>> be for everyone to work. I already put some stuff there, and created some
>> headings, but everyone is welcome to modify and add to this web page.
>>
>> Sasha.
>>
>> ------------------------------------------------------------------------
>> Dr. Alexandre Lebedev                 phone: (515)-294-8699
>> Department of Physics and Astronomy,  fax: (515)-294-6027
>> Iowa State University,
>> http://www.public.iastate.edu/~lebedev
>> Ames, IA 50011-3160                   lebedev@iastate.edu
>> ------------------------------------------------------------------------
>>
>>
>>
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>>
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