CLEO-c Workshop 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
CLEO-c Workshop 2
Data Assumptions
• Assume we will accumulate 3 fb-1 on the ψ”(3770)– 10 nb signal, 12 nb “other hadronic”:– About 3x107 DD pairs
• Assume BaBar & Belle will (each) have 400 fb-1 on the Υ(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.
CLEO-c Workshop 3
Big Advantage: Tagging:
Two important benefits:• Flavor ID • Unambiguous Reconstruction
– 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)
0D
0D
K+
e-
e+
e−e+
π−
CLEO-c Workshop 4
Rare Decays
e+ e−
0D
0D
K+
π−
π0
e+
e-
Example Study: D0 → π0 e+e−
(∆C=1 Weak Neutral Current)
• In 32290 generic D0 decays:– 1098 D0 → K−π+ tags (εB=3.4%)– 1543 D0 → K−π+ π0 tags (εB=4.8%)
Tag using:D0 → K−π+ (B = 3.83%)D0 → K−π+π0 (B = 13.9%)
With just these two modes, εBtag=8.2%
Working Group: What is the tradeoff: efficiency vs cleanliness
CLEO-c Workshop 5
Tagged events …if we don’t properlyexclude tagged tracks
Ability to get rid of this stuff is a keyadvantage!
επee x εBtag= 1.5%
~ 500 evtNotag
CLEO-c Workshop 6
Suppose επee.εBtag= 1.5 %
Suppose we have 3 fb-1 (~1.5x107 D0D0 pairs)Suppose we see 0 events
90% CL upper limit is ~5 x 10-6
About a factor of 100 improvement over PDGin most cases.
Most modes studied were in the 10-6 → 10-5 range
Its hard to imagine BaBar/Belle would not be in the same ballpark,although based on simple scaling I think we have the edge inclean modes where they are background limited. See Excel Table
See Bruce Yabsley’s talk in beyond SM working group
CLEO-c Workshop 7
CLEO-c B-fact
Simple spreadsheetanalysis tool available for working group.
For example…
CLEO-c Workshop 8
Some interesting examples:
1) B(D0 → γγ) - 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) Γ(D0 → ργ) / Γ(D0 → ωγ) (Fajfer et. al. hep-ph/0006054)- Individual BR’s small: ~10-6
- Long distance effects cancel in ratio.- Ratio should be ~1 (30% deviation means new physics)
See Will Johns’talk in beyond SM working group
Presently:90% CL Upper Limits < 2.4x10-4
For both modes
ργCLEO-II
ωγCLEO-II
CLEO-c Workshop 9
Mixing Phenomenology:
RiAeDK δ+− ≡π 0
D0
K−π+
DCS
CF
In hadronic decays:
MIXD0
WiAeDK δ+− ≡π 0
y = ∆Γ/2Γ (real)
D0 D0
K−
K+
W WD0 D0
x = ∆Μ/Γ (virtual)δ = δR–δW (important to measure)
r = A /A
CLEO-c Workshop 10
D0-D0 Mixing: At the Y(4S)
• Ultimately limited by Backgrounds & Systematics
Con
CLEO K3π analysis CLEO K*lν analysis
Pro
• Lots of data• Time evolution handle
CLEO-c Workshop 11
Experimental Situation (May/2001)
x0 0.1 0.2
0
-0.1
0.1
y
CLEO-c Workshop 12
D0-D0 Mixing: At the ψ”(3770)
• Tagging !- Flavor known- All tracks accounted for
• Quantum Correlations- opens up new avenues of
search:
Pro
e+ e−
0D
0D
π−
K+
K+
π−
Con• No Time evolution handle:
D0’s produced ~at rest
• Can’t measure ∆Γ directly usinglifetime differences.
CLEO-c Workshop 13
e+ e−
0D
0D
π−
K+
K+
π−
See hep-ph/0103110Gronau, Grossman & Rosner(and also working group tomorrow)
( ) ( ) ( ) ( )[ ]p̂Dp̂D p̂Dp̂D2
1ψ 0000 −−−=INITIAL
• The D0 and D0 are produced coherently in a JPC = 1−− state.
(assumes CP conserved)
+
−−
+
+
+−
=Γ 222
222
21 11
11
21
11
11
21),(
xyB
xyAff
02
01
02
01 DfDfDfDfA −=
02
01
02
01 DfDfDfDfB −=
• Time integrated decay rate to final state f1,f2: Looks slightlydifferent for C +initial states likeDDγ
CLEO-c Workshop 14
0D
0D
π+
K-
K-
π+Interesting Case 1:
Ratio of Rates:
0D
0D
π−
K+
K-
π+
( ) terms smaller ++=ππΓππΓ
−++−
+−+−22
21
),(),( yx
KKKK
Useful for probing x & y
CLEO-c Workshop 15
Interesting Case 2:
Asymmetry =
0D
0D
π−
K+
K+
Κ−CP+ eigenstate
0D
0D
π−
K+
KS
ρ0CP- eigenstate
0D
0D
π−
K+
K+
Κ−CP+ eigenstate
0D
0D
π−
K+
KS
ρ0CP- eigenstate
Useful for probing r & δ= 2 r cos δ
There are several other interesting cases to study:See Jon Rosner’s & Alexey Petrof’s talks in beyond SM working group
CLEO-c Workshop 16
Another Example: D0 →K0π+π− Dalitz Plot Analysis to extract mixing parameters:
c
u
u
d
d
sdu
K0D0
π+
π−
K∗−
CF: D0 → K∗− π+
Mix or DCS: D0 → K∗+ π−Fit for these in Dalitzplot…
…along with other good stuff: other K*’s, K2, ρ, ω, f0, f2…
CLEO-c Workshop 17
In CLEO II.V:Sensitivity to x & ywill be about 3%
See “wrong sign”decays at 5σ level.
See David Asner’s talk in beyond SM working group
CLEO-c Workshop 18
Yet another Example: D0 →π+π−π0 Dalitz Plot Analysis:
Also accessible from the D0 Interference !
D0 → π− ρ+
cu u
ddu
D0
ρ+
π−
D0 → ρ− π+
cu u
ddu
D0
π+
ρ−
D0 → π0 ρ0
c ddu ρ0
π0
u u
D0 → Κ0 π0
c sdu
Κ0
π0u u
D0 D0
CLEO-c Workshop 19
CLEO-II.V D0 →π+π−π0 Dalitz Plot Analysis (preliminary):
MD*-MD ρ+
ρ−
ρ0
KS
At CLEO-c we will have 5-10x more events with no background
CLEO-c Workshop 20
Direct CP violation:
D
f
22
δieA11
δieANeed two paths frominitial D to final state f.
D
f
2*2
δieA1*1
δieA
Compare D → f to D → f
21 *2
*1
δδ += iif eAeAA
2121
δδ += iif eAeAA
CLEO-c Workshop 21
Direct CP violation:
)cos()Re(2)sin()Im(2
212*1
22
21
212*1
22
22
δ−δ++
δ−δ=
+
−=
AAAAAA
AA
AAA
ff
ffCPFind:
Good News: We know large strong phase differences (δ1− δ2) are not uncommon in charm decays!This is an important ingredient.
Good/Bad News: Expect small weak phase differencesin Standard Model. SM ACP may be as big as 10-3
for some decay modes
Definitely a hunting ground for new physics.
CLEO-c Workshop 22
Observing this is evidence of CP
At the ψ”(3770)
e+ e−
0D
0D
π−
π+
K+
Κ−
e+e− → ψ” → D0D0
JPC = 1−−
i.e. CP+
Suppose both D0’s decay to CP eigestates f1 and f2: These can NOT have the same CP :
CP(f1 f2) = CP(f1) CP(f2) (-1)l = CP−
+ − (since l = 1)
CLEO-c Workshop 23
CP violation in Dalitz Plots:
Example Search: D0 → K− π+ π0
CLEO-c Workshop 24
Fit D0 and D0 Dalitz Plots separately and look for asymmetries:
Find ACP = 0.031 ± 0.086
DPdDD
DD∫+
−= 22
22
00
00
MM
MMACP
D0 - D0 “Difference” Plot
Q: Are structural differences that integrate to zero interesting?
Better sensitivity to new physics expected in CS modes. Some are under investigation: D0 → K−Κ+ π0 and D0 → π− π+ π0
This will be easier to do at a charm factorythan at Y(4S) due to backgrounds.
See Daniele Pedrini’stalk in beyond SM working group
CLEO-c Workshop 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..
CLEO-c Workshop 26
If time, end with something just for fun:Sensitivity to Large Extra Dimensions:
From Bijnens & Maul hep-ph/0006042
If there are n large extra dimensions the decay J/ψ → γ + (h,φ) may be sensitive to the compactification scale MS:
Rn ~ MP2MS
-(n+2)The size R of the extra dimension is given bywhere MP is the 4-dimensional Planck scale.
Look for
graviton or dilaton (undetected)
photonγ
J/ψ
h,φ
q
q
CLEO-c Workshop 27
If BR( J/ψ → γ + (h,φ) ) < 10-5
we can set these lower boundson MS (as a function of n).
Predicted photon spectrum
CLEO-c Workshop 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:
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