Beyond SM Physics at a CLEO Charm Factory (some food for thought) Mats Selen, UIUC, May/5/2001
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Transcript of Beyond SM Physics at a CLEO Charm Factory (some food for thought) Mats Selen, UIUC, May/5/2001
CLEO-c Workshop 1
• Data Assumptions• Tagging• Rare decays• D mixing• CP violation• Off The Wall
Beyond SM Physics at a CLEO Charm Factory
(some food for thought)Mats Selen, UIUC, May/5/2001
CLEO-c Workshop 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.
CLEO-c Workshop 3
Big Advantage: Tagging:
– 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)
e+ e
0D
0D
K+
e+
e-Two important benefits:• Flavor ID • Unambiguous Reconstruction
CLEO-c Workshop 4
• In 32290 generic D0 decays:– 1098 D0 K tags (B=3.4%)– 1543 D0 K tags (B=4.8%)
e+ e
0D
0D
K+
e+
e-
Tag using:D0 K (B = 3.83%)D0 K (B = 13.9%)
With just these two modes, Btag=8.2%
Working Group: What is the tradeoff: efficiency vs cleanliness
Example Study: D0 ee
(C=1 Weak Neutral Current)
Rare Decays
CLEO-c Workshop 5
ee x Btag= 1.5%
Tagged events
~ 500 evt
…if we don’t properly exclude tagged tracks
Ability to get rid of this stuff is a keyadvantage!
Notag
CLEO-c Workshop 6
Suppose ee.Btag= 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
Simple spreadsheetanalysis tool available for working group.
For example…
CLEO-c B-fact
CLEO-c Workshop 8
Some interesting examples:
1) B(D0 - 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) D0 / D0 (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
CLEO-II
CLEO-II
CLEO-c Workshop 9
Mixing Phenomenology:
x = /(virtual)
RiAeDK 0
= R–W (important to measure)
r = A /A
D0
K
DCS
CF
In hadronic decays:
MIXD0
y = /2(real)
D0 D0
K
K
W WD0 D0
WiAeDK 0
CLEO-c Workshop 10
D0-D0 Mixing: At the Y(4S)
• Lots of data• Time evolution handle
Pro
• Ultimately limited by Backgrounds & Systematics
Con
CLEO K3 analysis CLEO K*l analysis
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 ”(3770)
• No Time evolution handle: D0’s produced ~at rest
• Can’t measure directly using lifetime differences.
Con
• Tagging ! - Flavor known - All tracks accounted for • Quantum Correlations - opens up new avenues of search:
Pro
e+ e
0D
0D
K+
K+
CLEO-c Workshop 13
See hep-ph/0103110Gronau, Grossman & Rosner(and also working group tomorrow)e+ e
0D
0D
K+
K+
p̂Dp̂D p̂Dp̂D2
1ψ 0000 INITIAL
• The D0 and D0 are produced coherently in a JPC = 1 state.
(assumes CP conserved)
22
2
22
2
21 1
1
1
1
2
1
1
1
1
1
2
1),(
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 likeDD
CLEO-c Workshop 14
Interesting Case 1:0D
0D
K-
K-
0D
0D
K+
K-
terms smaller
22
2
1
),(
),(yx
KK
KK
Useful for probing x & y
Ratio of Rates:
CLEO-c Workshop 15
Asymmetry =
Interesting Case 2:
0D
0D
K+
K+
CP+ eigenstate
0D
0D
K+
KS
CP- eigenstate
There are several other interesting cases to study:See Jon Rosner’s & Alexey Petrof’s talks in beyond SM working group
0D
0D
K+
K+
CP+ eigenstate
0D
0D
K+
KS
CP- eigenstate
Useful for probing r & = 2 r cos
CLEO-c Workshop 16
Another Example: D0 K0Dalitz Plot Analysis to extract mixing parameters:
c
u
u
d
d
s
d
u
KD0
K
CF: D0 K +
Mix or DCS: D0 K Fit for these in Dalitzplot…
…along with other good stuff: other K*’s, K2, , , f0, f2…
CLEO-c Workshop 17
In CLEO II.V:Sensitivity to x & ywill be about 3%
See David Asner’s talk in beyond SM working group
See “wrong sign”decays at 5 level.
CLEO-c Workshop 18
Also accessible from the D0 Interference !
Yet another Example: D0 Dalitz Plot Analysis:
D0 +
cu u
dd
u
D0
D0 +
cu u
dd
u
D0
D0 0 c d
du
u u
D0 0 c s
du
u u
D0 D0
CLEO-c Workshop 19
At CLEO-c we will have 5-10x more events with no background
CLEO-II.V D0 Dalitz Plot Analysis (preliminary):
MD*-MD +
0
KS
CLEO-c Workshop 20
Direct CP violation:
Need two paths frominitial D to final state f.
D
f
22
ieA11
ieA
D
f
2*2
ieA1*1
ieA
Compare D f to D f
21 *2
*1
iif
eAeAA
2121
iif eAeAA
CLEO-c Workshop 21
Direct CP violation:
)cos()Re(2
)sin()Im(2
212*1
2
2
2
1
212*1
22
22
AAAA
AA
AA
AAA
ff
ff
CPFind:
Good News: We know large strong phase differences () 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 ”(3770)
e+ e
0D
0D
+
K+
e+e ” 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 + 0
CLEO-c Workshop 24
Fit D0 and D0 Dalitz Plots separately and look for asymmetries:
Find ACP = 0.031 0.086
DPd
DD
DD
22
22
00
00
MM
MMACP
D0 - D0 “Difference” Plot
Better sensitivity to new physics expected in CS modes. Some are under investigation: D0 K+ 0 and D0 + 0
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
Q: Are structural differences that integrate to zero interesting?
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/ + (h,) may be sensitive to the compactification scale MS:
Look for
graviton or dilaton (undetected)
photon
J/
h,
q
q
Rn ~ MP2MS
-(n+2)The size R of the extra dimension is given bywhere MP is the 4-dimensional Planck scale.
CLEO-c Workshop 27
If BR( J/ + (h,) ) < 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: