CLEO-c Workshop 1

1
Beyond SM Physics at a CLEO Charm Factory(some
food for thought)Mats Selen, UIUC, May/5/2001

• Data Assumptions
• Tagging
• Rare decays
• D mixing
• CP violation
• Off The Wall

2
Data Assumptions

• Assume we will accumulate 3 fb-1 on the ?(3770)
• 10 nb signal, 12 nb other hadronic
• About 3x107 DD pairs
• Assume BaBar Belle will (each) have 400 fb-1 on
  the ?(4S)
• 1.3 nb signal, 3 nb other hadronic
• About 5x108 cc pairs each
• Our competition will have 17 times more charm
  on 33 times more other hadronic background.

3
Big Advantage Tagging

• Two important benefits
• Flavor ID
• Unambiguous Reconstruction

e-
e
e-
e
p-
K

• Suppose efficiency x BR (all tags) 10 (more on
  this..)
• Will have 106 each tagged D0 and D per 1 fb-1
• Limits of order 10-6 possible from 3 fb-1 data
  (still pretty good)

4
Example Study D0 ? p0 ee-
Rare Decays
(DC1 Weak Neutral Current)

• In 32290 generic D0 decays
• 1098 D0 ? K-p tags (eB3.4)
• 1543 D0 ? K-p p0 tags (eB4.8)

Tag using D0 ? K-p (B 3.83) D0 ?
K-pp0 (B 13.9)
With just these two modes, eBtag8.2
Working Group What is the tradeoff efficiency
vs cleanliness
5
Tagged events
epee x eBtag 1.5
Notag
500 evt
6
(No Transcript)
7
CLEO-c
B-fact
Simple spreadsheetanalysis tool available for
working group.
8
Some interesting examples

• 1) B(D0 ? gg) - SM small 10-8 (Singer et. al.
  hep-ph/0104236)
• - good hunting for
  physics beyond SM.
• - no present limit,
  CLEO-c sensitivity 10-6

• 2) G(D0 ? rg) / G(D0 ? wg) (Fajfer et. al.
  hep-ph/0006054)
• - Individual BRs small 10-6
• Long distance effects cancel in ratio.
• - Ratio should be 1 (30 deviation means new
  physics)

See Will Johnstalk in beyond SM working group
9
Mixing Phenomenology
10
Pro

• Lots of data
• Time evolution handle

11
Experimental Situation (May/2001)
12
Con

• No Time evolution handle D0s produced at
  rest
• Cant measure DG directly using lifetime
  differences.

13
See hep-ph/0103110Gronau, Grossman Rosner (and
also working group tomorrow)
Looks slightlydifferent for C initial states
likeDDg
14

• Interesting Case 1

Ratio of Rates
15

• Interesting Case 2

CP eigenstate
Asymmetry
CP eigenstate
There are several other interesting cases to
study See Jon Rosners Alexey Petrofs talks
in beyond SM working group
16
Another Example D0 ?K0pp- Dalitz Plot Analysis
to extract mixing parameters
along with other good stuff other Ks, K2, r,
w, f0, f2
17
In CLEO II.V Sensitivity to x ywill be about
3
See wrong signdecays at 5s level.
See David Asners talk in beyond SM working group
18
Yet another Example D0 ?pp-p0 Dalitz Plot
Analysis
D0 ? K0 p0
K0
d
D0
D0
u
p0
19
CLEO-II.V D0 ?pp-p0 Dalitz Plot Analysis
(preliminary)
At CLEO-c we will have 5-10x more events with no
background
20
Direct CP violation
Need two paths frominitial D to final state f.
21
Direct CP violation
Good News We know large strong phase differences
(d1- d2) are not uncommon in charm decays! This
is an important ingredient.
Good/Bad News Expect small weak phase
differences in Standard Model. SM ACP may be as
big as 10-3 for some decay modes
Definitely a hunting ground for new physics.
22
At the ?(3770)
ee- ? ? ? D0D0
JPC 1--
i.e. CP
Suppose both D0s decay to CP eigestates f1 and
f2 These can NOT have the same CP
23
CP violation in Dalitz Plots
Example Search D0 ? K- p p0
24
Q Are structural differences that
integrate to zero interesting?
25
General Observation
High statistics background free DalitzPlot
analyses will be a great place to lookfor
interesting physics at CLEO-c
Not only Beyond SM, also QCD etc..
26
If time, end with something just for
funSensitivity to Large Extra Dimensions
From Bijnens Maul hep-ph/0006042
If there are n large extra dimensions the decay
J/? ? g (h,f) may be sensitive to the
compactification scale MS
27
If BR( J/? ? g (h,f) ) lt 10-5 we can set
these lower boundson MS (as a function of n).
Predicted photon spectrum
28
There is lots of interesting physics Beyond the
Standard Model that will be explored with
CLEO-c Find out more at tomorrows working group