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Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories1
Stefano BiancoLaboratori Nazionali di Frascati dell’INFN
Frascati, January 19th, 2006
Flavour Physics at-c Factories
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories2
CONTENTS
1. Past , Present and Foreseeable Future for TauC factories2. Flavour (Charm) Physics(see Antonio’s talk for onium)3. A List Of Open Questions and A Few Answers
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories3
1.
Past , Present and Foreseeable Future for TauC factories
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories4
Charm discoveryK.Niu, E. Mikumo, Y. Maeda Prog. Theor. Phys. 46 (1971) 1644
D+ K+
First observation of D mesons at accelerators
I.Peruzzi et al., Phys. Rev. Lett. 37(1976) 569.
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories5
Charm quark detectors over the years
R704E760E835
NA14
ARGUS
MARK IIII
E691CLEO2CLEO-C
PANDA
NOW
BABAR,BELLE
CDF,D0
BES
NA1BNL
SPEARADONE
COMPASS
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories6
• √s =3.770GeV ’’ coherent production of D meson pair
ee(3770)DD WHY ?
• Large , low multiplicity
• Pure initial state: no fragmentation
• Double tag measurements: no background
• Clean neutrino reconstruction
• Coherent initial state
• Large , low multiplicity
• Pure initial state: no fragmentation
• Double tag measurements: no background
• Clean neutrino reconstruction
• Coherent initial state
CLEO-c
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories7
Tau-charm Factories proposed in the past
• 1987 proposed at CERN• 1989 proposed at SLAC• 1990 proposed in Spain• 1992 proposed in ITEP • 1994 proposed at Argonne• 1996 micro-workshop at Frascati (G.Capon
Convener)• …• 2005 a study in Frascati
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories8
THE CHARMING COMPETITION
• CLEO-c tau-charm factory, running. goal=3fb-1 DD– started Sep 2003, as of April 2005 265 pb-1 integrated at ’’. Luminosity below
project goal=3 1032cm-2s-1. End in 2008.
• Beijing tau-charm factory BEPC-II, design 1033cm-2s-1, commissioning in 2006
• BABAR (end in 2008)• BELLESBELLE ???• Frascati tau-charm Study (2005):
– 2x108 reconstructed DD events– L=1034cm-2s-1– 100fb-1/y– start in 2011– 30x CLEO-c– 2x BEPC-II after 1 y– ~10x BABAR/SBELLE withmuch better systematics
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories9
Detector(CLEOIII –like)VERYCHALLENGINGAND AMBITIOUS
• tracker• RICH• ECAL• solenoid• ermetic 4
geometry• potent DAQ• open trigger
1.5 T now,... 1.0T later
93% of 4p/p = 0.35%
@1GeVdE/dx: 5.7%
@minI
93% of 4E/E = 2% @1GeV
= 4% @100MeV
83% of 4% Kaon ID with
0.2% fake @0.9GeV
85% of 4For p>1 GeV
Trigger: Tracks & ShowersPipelinedLatency = 2.5s
Data Acquisition:Event size = 25kBThruput < 6MB/s
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories10
2. Flavour Physics
at a tau-C Factory
(see Antonio’s talk for onium)
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories11
High-impact Physics & Engineering Database
b
t
sd
u c
CPV, mixing and rare decays in
Charm sector are a probe for New Physics
Why (only) 3 families ?
Quark c is the only HQup-type probe
In the charm sector, SM contributions to CPV, mixing
and rare decays are small (GIM)
But how small?CPV asimm 10-3
D0D0bar mixing 10-3—10-10Rare decays 10-9 – 10-19
Higgs ?
HI ENERGY
SM
FSI corrections are important
Quantitative predictions via
1/mQ expansions are possible
Quark c is the lightest heavy quark
Studying the c-quark provides sensitivity and discovery potential for New Physics. After the
discovery (?) of Higgs @ LHC, New Physics manifestationsin c-quark (and in b-quark) important to
distinguish among models.
FSI corrections are important
QCD LO ENERGY
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories12
• √s =3.770GeV ’’ coherent production of D meson pairs• L~1034cm-2s-1, 100 fb-1/y• 2x108 DD pairs detected (30% eff*acc, extrap. from CLEO-c) , in uniquely
clean environment, per year.• Search for New Physics:
1. Direct CP Violation in SCSD asymmetries, and directly in integrated rates. Sensitivity 10-4, SM PREDICTION 10-3.
2. Search for direct CPV in CFD and/or DCSD, where SM PREDICTS NO CPV
3. Mixing exploiting coherence, unique feature of threshold production. Cannot study mixing in time evolution of rates, but only in integrated rates. In most channels, DCSD concurrent process does not exist thanks to Bose-Einstein statistics (coherent C=-1 quantum state). By comparing semilept and hadronic, measure strong phaseshift
4. Rare decays: FCNC D+ h l+l-, D0l+l-, SM PREDICTION 10-9 Sensitivity 10Sensitivity 10-7-7 - 10 - 10-8-8
ee(3770)DD “NEW PHYSICS” PROGRAMME
Bibliography:1. SB, Fabbri, Benson, Bigi Riv.Nuovo Cim. 26,7-8, 2003 hep-ex/0309021. 2. I.Bigi and A.Sanda CP Violation, Cambridge, 2000.3. CLEO-c proposal (2001).4. Burdman Shipsey Annu. Rev. Nucl. Part. Sci. 2003. 53:431–995. Frascati Futuro report (Antonelli, SB, Bloise, Bossi, Miscetti et al.)
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories13
Also, tau physicsee’’
• √s =3.770GeV ’’ production of tau lepton pairs, ~3nb.• L~1034cm-2s-1, 100 fb-1/y• LNV decay sensitive to SUSY, (109 events) / (three
years). BABAR best limit 7x10-8 (90%cl) dominated by systematics, background Running at threshold reduces systematics.
• Robust Standard Model physics programme:– precise measurement of mass– weak couplings (purely leptonic and semileptonic decays)– test of CVC rule, and implications on anom. magn. moment of
muon.– etc (see Gino Isidori’s talk April 2005 Frascati, and Futuro
report Sect.5.5)
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories14
CPV ASYMMETRIES
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories15
For a two-amplitude decay
ii = strong phase
CP asymmetry:
2 different weak amplitudes strong phase-shift
AAtottot = g1M1ei1 + g2M2ei2
CP conjugate
AAtottot = g1M1ei1 + g2M2ei2
** **
aaCPCP==2Im(2Im(gg2 2 gg11**) sin() sin(11--
22)M)M11MM22|g|g11||22MM11
22+|g+|g22||22MM2222+2Re(+2Re(gg2 2 gg11**)cos()cos(11--22)M)M11MM22
|Atot|2-|Atot|2
|Atot|2+|Atot|2==
CP VIOLATING INTEGRATED ASYMMETRIES
are needed for CPV asymmetry Single Cabibbo-suppressed decaysIn DSCD and CFD only one weak amplitude NO CPV WITHIN SM
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories16
In plain words…
• SM predicts CPV at the 10-3 level in SCSD observation would be a *** result
• SM predicts ZERO CPV in CFD and DCSD observation of CPV in those decays is a ***** discovery of New Physics
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories17
Search for CP violation via Dalitz plot analysis of Singly-Cabibbo-suppressed Decays
• Use full decay info, not only BR must determine amplitude coefficients and phases
• Final state results from the interference of all intermediate states
• Differences between amplitude and/or phases patterns in a Dalitz analysis betw conjugate states (i.e., D+ vs D-), would be evidence of CP violation (ref. I.Bigi,A.Sanda “CP Violation”)
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories18
Ds , D+ KK
Ds+ K+ K+
D+ K+ K+
D sD
2Km
2KKm 2
KKm
2Km
KKm
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories19
+ -2
K Km
- +2
K πm
K+ Kprojection
K projection
Yield D± = 7106 92
S/N D± = 8.62
Decay Fraction and phases
K*(892) = 20.7 1.0 % (0 fixed)
(1020) = 27.8 0.7 % (243.1 5.2)°
K*(1410) = 10.7 1.9 % (-47.4 4.9)°
K* (1430) = 66.5 6.0 % (61.8
3.8)°
f0(1370) = 7.0 1.1 % (60.0 5.3) °
a0(980) = 27.0 4.8 % (145.6 4.3)°
f2(1270) = 0.8 0.2 % (11.6 7.0) °
(1680) = 1.6 0.4 % (-74.3 7.5) °
Preliminary
D± KK
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories20
Coefficients: D±,, DD++,, DD--
Phases: DD±±,, DD++,, DD--
D+/D- split sample analysis Preliminary!
No evidence of CPV
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories21
D0D0 MIXING
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories22
0
0
2221
12
0
011
P
P
HH
HH
P
P
ti
2/jkjkjk imH
Processes which allow mixing appear in H12 and H21.
00 PP
The time evolution of flavour eigenstates is given by the Schrödinger equation
00 , PP
If are not mass eigenstates. Mass eigenstates are(assuming CP conservation)
002,1 2/1 PPP
012 H 021 H 00 , PP,
)cos(21)( 2
200 1 mteeetPP
ttt
and mixing amplitude is
mx
2y
Mass and width differences are parametrizedby
Formalism of P0-P0 mixing 1x 1y
mixing can be described by the ratio r
2)(
)( 22
0
00 yx
fP
fPPr
|x|>0 mixing is caused by
genuine
transitions(f=2)
x splits masses
|y|>0 mixing is caused by the
short-lived component
disappearing rapidly, leaving behind the long-
lived component,
made of and
y splits lifetimes
0P 0P
00 PP
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories23
2
,,2
222
bcsW
dq
mm
mm
SHORT DISTANCE
KK,
0D0K
0D0K
LONG DISTANCE
q SD/LD x=m/ y=)
c SD~LD 0.48 100%
s SD<<LD <5% <1%
t SD>>LD 0.75 ?
t SD>>LD >22 ?
)(0 sdK
)(0 bdBd
)(0 ucD
)(0 bsBs
K0, D0, B0 _ Where’s The Difference ?
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories24
Theoretical “guidance”
From compilation of H.N.Nelson hep-ex/9908021
Triangles are SM x Squares are SM
y
Circles are NSM x
“D0D0 mixing is a window on New
Physics”
_
310, SM
yx
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories25
2
_
Measure yCP, the y parameter for CP
eigenstates
Measure r
2)(
)( 22
0
00 yx
fD
fDDr
mixedKCP
KKCP
KKKKCP
SS
HADRONIC DECAYS
SEMILEPTONIC DECAYS
Kf Kf
(1 +2)/2
TECHNIQUES FOR STUDYING D0D0 MIXING (I)
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories26
_
Measure r 2)(
)( 22
0
00 yx
fD
fDDr
HADRONIC DECAYS
Kf
0* DD
D* tags D0
flavour
KDD 00
mixing
Cabibbo-Favoured Decay
tryt
rrefD
fDr DCSDCS
tWS 2)(
)( 2
0
0
KD0
Double Cabibbo-Suppressed Decay
Strong phase between CFD and
DCSD mixes x and y
sincos
sincos
yxx
xyy
0D Ku
s
s
u
c sd
u
c
csV
udV
c
u ud
u
sK
cdVusV
0D
via
TECHNIQUES FOR STUDYING D0D0 MIXING (II)
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories27
_
Measure r 2)(
)( 22
0
00 yx
fD
fDDr
0* DD
D* tags D0
flavour
mixing
Cabibbo-Favoured Decay
SEMILEPTONIC DECAYS
Kf
KDD 00
0DKu
s
s
u
c s
c
csV
rfD
fDrWS
)(
)(0
0
via
TECHNIQUES FOR STUDYING D0D0 MIXING (III)
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories28
• Direct measurement of yCP requires good lifetime resolution • Measuring rws in hadronic decays requires to disuntangle rDCS from r; and the knowledge of
• Measuring rws in semileptonic decays provides the r parameter, but it is experimentally more difficult•MEASURING rws at tau-C PROVIDES THE r PARAMETER, SINCE QUANTUM CORRELATIONS FORBID DECAY TO IDENTICAL FINAL STATES (NO DCSD POLLUTION).
TECHNIQUES FOR STUDYING D0D0 MIXING (Concl.)
_
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories29
STATUS OFD0D0
MIXINGAS OF SPRING 2004
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories30
• √s =3.770GeV ’’ coherent production of D meson pairs, L~1034cm-2s-1, 100 fb-1/y• 2x108 DD pairs detected (30% eff*acc, extrap. from CLEO-c) , in uniquely clean
environment, per year.• Standard Model physics programme: Absolute branching ratios; Vcd, Vcs from
semileptonic decays; SL Form Factors; Charm decay constants fD from Dlight quarks in Dalitz plots; etc.
ee(3770)DD
STANDARD MODEL FLAVOUR PHYSICS
Ref: SB, Fabbri, Benson, Bigi Riv.Nuovo Cim. 26,7-8, 2003 hep-ex/0309021. I.Bigi and A.Sanda CP Violation, Cambridge, 2000.
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories31
• Charmonium spectroscopy• QCD• Hybrids, glueballs
eeJ/X
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories32
QUESTIONS, AND MY VERY FEW ANSWERS
• Physics– Is the cF a significant help to disentangle among non-SM models after the discovery of
SUSY ?– Are the SM measurements significant in the field of b and c physics ?– Is the SM programme of a cF strong enough to allow success even is SUSY is not
discovered at LHC ?• Detector
– must be all-purpose detector !– Can we start design ?– Impact on Frascati infrastructure ? VERY BIG, INTERNATIONAL ENTERPRISE– Cost ?
• Machine– Impact on Frascati infrastructure ? VERY BIG, INTERNATIONAL ENTERPRISE– symmetric/asymmetric ?– Fits DAFNE building ? NO– Cost 100MEuro ? MORE
• Competition– Is a 2011 Frascati tcF going to be competitive and timely wrt CLEO-c and BES ?– Is a tcF really necessary after BABAR and, expecially, BELLE/SBELLE ?
• Sociology– Is the Frascati community interested in working hard on a onsite world-class project ? YES !– Is the whole INFN community interested ?– Is the world community interested ?– This is a Big Science project, Isn’t Big Science HEP over ?
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories33
http://w
ww.lnf.in
fn.it/conference/dif0
6/
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories34
CONCLUSIONS
• The Physics programme at a tau-C factory is very large and robust:
1. BSM: CPV, Mixing, Rare decays, tau rare decays2. SM: absolute branching ratios, meson decay constants, CKM elements from semileptonic decays, charmonium spectroscopywith some items unique or superior wrt B-factories (underlined above). Is this uniqueness sufficient to justify it ?
• Machine and detector are likely to be costly and challenging, expertise does exist in Frascati but has to be an international enterprise.
• Timing is the critical issue against competition
•Flavour physics is necessary in the LHC era if “Beyond the SM Physics” is discovered
Frascati Jan 19th, 2006 SB - Flavour physics at tau-charm Factories35
QUESTIONS SLIDES
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