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Re: updated talk for PID
Hall D PID Mail List:
To Eugene -
since you did not actually do a kinematic fit, you should probably
remove that statement from your talk, it might be a bit misleading
as I do talk about fitting in the overview document.
Cheers - Curtis
On Wed March 19 2008, Matthew Shepherd wrote:
> Hall D PID Mail List:
>
>
> Hi Curtis,
>
> I strongly agree with backing off those numbers in the document.
>
> My concern is that you are presenting only the good part of the full
> story. We wouldn't want to give the impression that additional PID is
> unnecessary because we've already solved the problem with kinematic
> fitting. There is not enough time to fully understand the rest of the
> story regarding which backgrounds leak in. I think this means you
> should avoid such quantitative statements in the text.
>
> Perhaps there are less provocative aspects of Matt's work that could
> be presented to demonstrate it is something we are hard at work it?
> Showing nearly perfect signal purity with 50% efficiency in the "key
> channel for strangeonium hybrids" would be great ammo for shooting
> down any claim we need supplementary PID.
>
> -Matt
>
>
> On Mar 19, 2008, at 5:47 PM, Curtis A. Meyer wrote:
>
> > Hi Matt (Shepherd),
> >
> > yes, they do seem to imply that with kinematic fitting and
> > strangeness
> > conservation, we are done. I do not believe this. I suspect that if we
> > were to include channels that had hyperons (Lambda, Sigma), and a
> > single kaon, we would have more problems. I would guess that if we
> > had a missing neutron (or proton), the 1-C fits would not be nearly
> > so powerful.
> >
> > What I take from these is that kinematic fitting will help us a lot
> > (every experiment I have done has seen this), but even though I
> > put the numbers in the document, I think I want to back off on this
> > at the moment until we have a better understanding, or at least
> > recast Matt Bellis's work as a hypothical??
> >
> > Opionions anyone?
> >
> > thanks -- Curtis
> > On Wed March 19 2008, Matthew Shepherd wrote:
> >> Hall D PID Mail List:
> >>
> >>
> >> Hi Eugene and Matt,
> >>
> >> I was also struck by this passage in the document and the studies
> >> that
> >> Matt did. I don't doubt the power of kinematic fitting, but these
> >> results are quite surprising. In fact, taken at face value, they
> >> would say forget any other PID -- we don't need it. For some of the
> >> high multiplicity all neutral channels we were happy with S:B of
> >> about
> >> 5:1 and 10% efficiency. You have strange channels with S:B =
> >> infinity
> >> and ~50% efficiency -- that's quite good.
> >>
> >> I can't help but wonder what the background will be from broken
> >> events. For example, if you have an event where miss a pion you can
> >> make another one or two pions in the event a kaon to recover some of
> >> the lost four momentum.
> >>
> >> Matt
> >>
> >> On Mar 19, 2008, at 5:25 PM, Eugene Chudakov wrote:
> >>
> >>> Hall D PID Mail List:
> >>>
> >>> Matt,
> >>>
> >>> thanks for sending me your talk on the event fitting.
> >>> For my current studies I (in fact) did not use any fitting. I just
> >>> selected particle combinations, balancing the initial and final 3-
> >>> momentum and
> >>> the energy. Again, it was very simple: I selected the same absolute
> >>> cuts
> >>> in GeV for all events, without calculating the individual
> >>> covariances for each event.
> >>> Therefore, there must be a room for improvement.
> >>> I am sure you have already perfected this method.
> >>>
> >>> If I did any new step with this study, it is considering the minimum
> >>> bias
> >>> background from PYTHIA.
> >>> The pion suppression is only a factor of 0.4-0.6 for a kaon
> >>> candidate,
> >>> the overall suppression is about 0.2. The proton PID gives another
> >>> factor of 4.
> >>> Indeed, a factor of 3 comes from combinatorics, while some events
> >>> may have
> >>> no proton as well.
> >>>
> >>> Eugene
> >>>
> >>> ------------------------------------------------------
> >>> Eugene Chudakov
> >>> http://www.jlab.org/~gen
> >>> phone (757) 269 6959 fax (757) 269 5703
> >>> Thomas Jefferson National Accelerator Facility
> >>> 12000 Jefferson Ave, Newport News, VA 23606 USA
> >>>
> >>> On Wed, 19 Mar 2008, Matt wrote:
> >>>
> >>>> Hi Eugene,
> >>>>
> >>>> The kinematic fit mentioned in your talk, is that the fitter
> >>>> that I
> >>>> checked into the repository under $HALLD_HOME/src/libraries/PID?
> >>>> Or a
> >>>> different one? I see you're doing a different study than what I
> >>>> did, but I
> >>>> found that using time-of-flight info from the BCAL and forward TOF
> >>>> got you
> >>>> quite far in trying to do kaon physics, though I had a simpler
> >>>> physics
> >>>> background than the full pythia spectrum.
> >>>>
> >>>> Matt
> >>>>
> >>>>
> >>>> On Wed, Mar 19, 2008 at 3:54 PM, Eugene Chudakov gen <gen@jlab.org>
> >>>> wrote:
> >>>>
> >>>>> Hall D PID Mail List:
> >>>>>
> >>>>>
> >>>>> I updated the slides, including new pictures and adding more info.
> >>>>>
> >>>>> It can be found at:
> >>>>> http://www.jlab.org/~gen/gluex/talk_pid_rev.pdf<http://www.jlab.org/%7Egen/gluex/talk_pid_rev.pdf
> >>>>>>
> >>>>>
> >>>>> The talk source is located at
> >>>>> jlabl1:/home/gen/tex/GLUEX/talk_pid_march_2008.tex
> >>>>> The pictures are stored at
> >>>>> jlabl1:/home/gen/tex/GLUEX/pictures/plot_glx_*.pdf
> >>>>> For each picture there are also .epsi and .ps files.
> >>>>>
> >>>>> Eugene
> >>>>>
> >>>>> ----------------------------
> >>>>> Eugene Chudakov
> >>>>> JLab
> >>>>>
> >>>>>
> >>>>
> >>>>
> >>>> --
> >>>> --
> >>>> ----------------------------
> >>>> Matt Bellis
> >>>> Carnegie Mellon University
> >>>> (office) 412-268-6949
> >>>> (cell) 412-310-4586
> >>>> ----------------------------
> >>>>
> >>>
> >>
> >
> >
> >
> > --
> > Professor Curtis A. Meyer Department of Physics
> > Phone: (412) 268-2745 Carnegie Mellon University
> > Fax: (412) 681-0648 Pittsburgh PA 15213-3890
> > cmeyer@ernest.phys.cmu.edu http://www.curtismeyer.com/
>
--
Professor Curtis A. Meyer Department of Physics
Phone: (412) 268-2745 Carnegie Mellon University
Fax: (412) 681-0648 Pittsburgh PA 15213-3890
cmeyer@ernest.phys.cmu.edu http://www.curtismeyer.com/