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Re: updated talk for PID
Hall D PID Mail List:
Hi Eugene,
Yes, so Curtis could for example present a summary of these results in
addition to something from Matt in his overview document to help
quantify the need for supplemental PID. (As is there is a
contradiction between your talk and Curtis' doc.)
I agree that 1/5 S/B is not good for a search for new states using
amplitude analysis.
-Matt
On Mar 19, 2008, at 6:23 PM, Eugene Chudakov wrote:
> Hi,
>
> well, my conclusion given in the talk is that without an additional
> PID
> we can not identify strange events with a reasonable purity, at
> least in one
> reaction I tried. The final signal/background I could get is about
> 1/5,
> which I guess is poor for a search for new phenomena.
>
> On the other hand, an additional factor of 20 must be sufficient.
> Such a factor is provided by typical threshold Cherenkov detectors.
>
> Regards,
> 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, 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/
>>
>>
>