The last* CLEO-c double tag event

March 7, 2008

lastdt-edit.png

(* last = last confidently-identified fully-reconstructed Ds Ds* event)

CLEO-c stopped taking data earlier this week.  We looked in the last data run (7:38 am to 8 am) of just over 61 thousand events for collisions that produced Ds mesons, and we actually found one.  Even better, we found an event where you could see both the Ds+ and Ds-, and where the photon from the Ds*+ → γ Ds+ transition was visible.  Above, you can see the event display, with all the tracks labeled; the event is consistent with the following sequence of events:

  • e+ e- → γ → Ds*+ Ds-
    • Ds*+ → γ Ds+
      • Ds+K- K+ π+ π+ π-
    • Ds-KS K-
      • KSπ+ π-

It was actually unlikely that we’d find such a nice event.  For the amount of data in the last run, we would expect roughly 75 Ds* Ds events.  Our full reconstruction efficiency (getting both Ds candidates) is somewhat less than 1%, so we had a good chance of winding up with zero events like this.  It’s nice to be lucky though.

About these ads

One Response to “The last* CLEO-c double tag event”

  1. carlbrannen Says:

    I was about to comment that one of the pi particles had the wrong charge. On my monitor, both the blue pis look like they’re marked “pi-” because the vertical bar distinguishing + from – is hard to see. Sure enough, the + particles are going counter clockwise and the – particles the other way.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s