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B. Golob, Ljubljana Univ. Charm Physics 1 BaBar School, SLAC, Oct 2009
Boštjan Golob
University of Ljubljana, Jožef Stefan Institute & Belle Collaboration
Charm Physics at
B-factories University
of Ljubljana
“Jožef Stefan”
Institute
BaBar Physics School,
SLAC, October 25-30, 2009
B. Golob, Ljubljana Univ. Charm Physics 2 BaBar School, SLAC, Oct 2009
Outline
1. Generalities on charm of beauty
2. D0 Mixing
decays to CP states
WS hadronic decays
t-dependent Dalitz
CPV
3. Rare decays D0 l+l-
4. Ds leptonic decays
Ds mn
5. Spectroscopy
exotic states, Z+(4430)
6. Summary
7. Bonus material
B. Golob, Ljubljana Univ. Charm Physics 3 BaBar School, SLAC, Oct 2009
Introduction
Dual role of charm physics
- experimental tests of theor. predictions (most notably of (L)QCD);
improve precision of CKM measurements (B physics);
example: leptonic decays of D mesons → decay constants,
tests of LQCD; Dr. Jeckyll
- standalone field of SM tests and search for new phenomena
(SM and/or NP);
example: mixing and CPV in D0 system Mr. Hyde
B. Golob, Ljubljana Univ. Charm Physics 4 BaBar School, SLAC, Oct 2009
Introduction
Experiments
s(c c) 1.3 nb (~1.2x109 XcYc pairs)
continuum production * c
c
on resonance production
e+e- → U(4S) → B0B0, B+B-
s(BB) 1.1 nb (~109 BB pairs)
e+e- → y(3770) → D0D0, D+D-
(coherent C=-1 state);
~800 pb-1 of data
available at y(3770);
2.8x106 D0D0
(+ ~600 pb-1
at ECM=4170 MeV);
5.7 fb-1 on tape
s(D0; pt>5.5 GeV,|y|<1)≈
≈13 mb
75x109 D0’s
very diverse exp. conditions
We all live with the
objective of being happy;
our lives are all different
and yet the same.
Anne Frank (1929 -1945)
B-factory=charm factory
B. Golob, Ljubljana Univ. Charm Physics 5 BaBar School, SLAC, Oct 2009
2
000
2
)(tDf
yix
p
qDfe
dt
fDdN t
D0 mixing
Time evolution flavor states ≠ Heff eigenstates:
(defined flavor) (defined m1,2 and 1,2)
00
2,1 DqDpD
)0()( 2,12,12,1
tDetD
ti
;2
; 2121
y
mmx
ttmi
etyix
Dp
qt
yixDtD 2000
2sinh
2cosh)(
|x|, |y| << 1
q2
P0 = K0, Bd0, Bs
0 and D0
SM: |x|, |y| O(10-2)
D0 only P0 system with uplike quarks;
D0 mixing FCNC of uplike quarks
Decay time distribution of experimentally accessible states D0, D0
sensitive to mixing parameters x and y, depending on final state
P0 q1
P0 q2
q1
B. Golob, Ljubljana Univ. Charm Physics 6 BaBar School, SLAC, Oct 2009
D0 mixing
if mi = mj due to CKM unitarity:
no mixing
Phenomenology P0-P0 transition → box diagram at quark level
P0: any pseudo-scalar meson;
specific example of D0
c
u
u
c
d, s, b
d, s, b
W+ W- D0 D0
c
u
u
c
d, s, b d, s, b
W+
W-
D0 D0
Vci
Vcj
Vuj*
Vui* j
bsdji
iujcjciuiwk mmVVVVDHD
,,,
**00
|VcbVub*|<< |VcsVus*|, |VcdVud*|
assuming unitarity in 2 generations
0
55
0
2
222**
2
2020 |)1()1(|
)(
4DcucuD
m
mmVVVV
GDHD
c
dsusudcdcs
FC
w
m
m
G. Burdman, I. Shipsey,
Ann.Rev.Nucl.Sci. 53, 431 (2003) DCS SU(3) breaking
homework: estimate leading contrib. to box diagram for K0 and Bd,s
0 mixing
O. Nachmtann, Elem. Part. Phys., Springer-Verlag
B. Golob, Ljubljana Univ. Charm Physics 7 BaBar School, SLAC, Oct 2009
n nD
C
w
C
w
D
C
w
D
ijD
D
jeffi
ij
iEM
DHnnHD
M
DHDM
M
M
DHDiM
0110
020
2
1
2
1
2
||)
2(
D0 mixing
Phenomenology
2nd order in pert. th.::
short distance:
|x| ~ O(10-5)
c
u
u
c
D0 D0 NP
common statement: mixing
with large x sign of NP;
Dn
nDnD
MEiEM
PViEM
11
long distance: contributes to y and x; y is affected by sum over
real intermediate states;
x also affected by
sum over off-shell states;
|x|, |y| ≤ O(10-2) I.I. Bigi, N. Uraltsev, Nucl. Phys. B592, 92 (2001);
A.F. Falk et al., PRD69, 114021 (2004)
D0 D0
K+
K-
D0 mixing is a rare process
B. Golob, Ljubljana Univ. Charm Physics 8 BaBar School, SLAC, Oct 2009
D0 mixing
Bs Bd D0
P(P0 P0)
P(P0 P0)
x=26, y=0.15 x=0.8, y=0
x=0.01, y=0.01
Phenomenology
B. Spinoza (1632 -1677)
All things excellent are as difficult
as they are rare.
B. Golob, Ljubljana Univ. Charm Physics 9 BaBar School, SLAC, Oct 2009
D0 mixing
Common exp. features
D*+ →D0s+
charge of s flavor of D0;
M=M(D0s)-M(D0)
(or q=M-m)
background reduction
D0 decay products vertex;
D0 momentum & int. region;
p*(D*) > 2.5 GeV/c
eliminates D0 from b → c
20
2
)(1tA
yix
p
qA
dt
fDd
efft
B. Golob, Ljubljana Univ. Charm Physics 10 BaBar School, SLAC, Oct 2009
K+K- K-+ +-
Nsig 111x103 1.22x106 49x103
P 98% 99% 92%
D0 mixing Decays to CP eigenstates
CP even final state;
if no CPV:
CP|D1> = |D1> t=1/1;
K-+: mixture of CP states
t=f(1/1,1/2)
D0 → K+K- / +-
AM, : CPV in mixing and interference
(addressed later)
yxA
y
KK
Ky
CPVno
M
CP
t
t
sin2
cos
1)(
)(
S. Bergman et al., PLB486, 418 (2000)
Reconstruction Belle, PRL 98, 211803 (2007), 540fb-1
M(K+K- ) ,
q=M(K+K- s)- M(K+K- )- M(),
st, selection optimized on MC
B. Golob, Ljubljana Univ. Charm Physics 11 BaBar School, SLAC, Oct 2009
D0 mixing Belle, PRL 98, 211803 (2007), 540fb-1
Decays to CP eigenstates
c2/ndf=
1.084
(ndf=289)
simultaneous binned likelihood fit to decay-t, common free yCP
B. Golob, Ljubljana Univ. Charm Physics 12 BaBar School, SLAC, Oct 2009
D0 mixing Belle, PRL 98, 211803 (2007), 540fb-1
Decays to CP eigenstates
K+K-/+-
and K-+ratio evidence
for D0 mixing (regardless of
possible CPV)
3.2 s
(4.1 s
stat. only)
+ )%25.032.0
31.1(
CPy
simultaneous binned likelihood fit to decay-t, common free yCP
B. Golob, Ljubljana Univ. Charm Physics 13 BaBar School, SLAC, Oct 2009
D0 mixing Belle, PRL 98, 211803 (2007), 540fb-1
yCP=(1.24±
0.39±0.13)%
Decays to CP eigenstates
K+K-/+-
and K-+ratio evidence
for D0 mixing (regardless of
possible CPV)
3.2 s
(4.1 s
stat. only)
+ )%25.032.0
31.1(
CPy
BaBar, PRD78, 011105 (2008), 384fb-1
yCP currently
most precisely
measured param.
simultaneous binned likelihood fit to decay-t, common free yCP
B. Golob, Ljubljana Univ. Charm Physics 14 BaBar School, SLAC, Oct 2009
D0 mixing
WS decays (non-CP)
D*+ → D0 slow+ D0 → D0 → K+ -
DCS decays interference;
sincos'
sincos'
xyy
yxx
t-dependence to separate DCS/mixed
BaBar, PRL 98, 211802 (2007), 384fb-1
: unknown strong phase DCS/CF
t
mixinterf
D
DCS
D etyx
tyRR
tDK
2
22
.
20
4
'''
)(
reconstruction
NWS=4030±90;
fit
R: sum of 3 Gaussians;
RS sample: t=(410.3±0.6) fs
WS
sample
DCS
B. Golob, Ljubljana Univ. Charm Physics 15 BaBar School, SLAC, Oct 2009
1s
2s
3s
4s
5s
likelihood
contours
3.9s
D0 mixing
WS decays (non-CP)
Result
x’2, y’ region
BaBar, PRL 98, 211802 (2007), 384fb-1
evidence
for D0 mixing
Belle, PRL 96, 151801 (2006), 400fb-1
95% C.L. (x’2, y’) contour
frequentist, FC ordering
RD = (3.03 ± 0.16±0.10 ) ·10-3
x’2 = (-0.22 ±0.33±0.21) · 10-3
y’ = (9.7 ±4.4±3.1) · 10-3
RD = (3.64 ± 0.17 ) ·10-3
x’2 = (0.18 ± 0.210.23) · 10-3
y’ = (0.6 ± 4.03.9) · 10-3
uncertainty includes syst. error
in y’=ycos-xsin,....
at Cleo-c
B. Golob, Ljubljana Univ. Charm Physics 16 BaBar School, SLAC, Oct 2009
D0 mixing
t-dependent Dalitz analyses different types of interm. states;
CF: D0 → K*-+
DCS: D0 → K*+-
CP: D0 → r0 KS
if f = f populate same Dalitz plot;
relative phases determined
(unlike D0 → K+-);
D0 →KS +-
B. Golob, Ljubljana Univ. Charm Physics 17 BaBar School, SLAC, Oct 2009
D0 mixing
t-dependent Dalitz analyses different types of interm. states;
CF: D0 → K*-+
DCS: D0 → K*+-
CP: D0 → r0 KS
if f = f populate same Dalitz plot;
relative phases determined
(unlike D0 → K+-);
t-dependence:
regions of Dalitz plane →
specific t dependence f(x, y);
titi
titi
S
eemmp
q
eemm
tDKtmm
21
21
),(2
1
),(2
1
)(),,(
22
22
022
A
A
M
sum of intermediate states:
1,2=f(x,y);
n.b.: K+-:x’2, y’ m±
2 = m2(KS±),
NRr i
NR
i
r eammBeamm
),(),( 2222A
t
access directly x, y
D0→f
D0→f
B. Golob, Ljubljana Univ. Charm Physics 18 BaBar School, SLAC, Oct 2009
D0 mixing
t-dependent Dalitz analyses
Nsig= (534.4±0.8)x103
P 95%
Dalitz fit projections;
decay-t fit projection;
K*(892)+
K*X(1400)+
K*(892)- r/w
t [fs]
t = (409.9±0.9) fs
Belle, PRL 99, 131803 (2007), 540fb-1
)%24.033.0(
)%29.080.0(
14.010.0
16.013.0
y
x
most sensitive
meas. of x 95% C.L.
region of
(x,y)
B. Golob, Ljubljana Univ. Charm Physics 19 BaBar School, SLAC, Oct 2009
D0 mixing
D0: first two quark generations;
CKM elements ≈ real;
using CKM unitarity:
bellow current exp. sensitivity;
signals New Physics
CP violation Vcs
Vus*
D0 K-
K+
)(VV
VV
Df
Df-
uscs
ubcb 3
*
*
0
0
10~arg O
)(
0
0
0
0
0
0
2/1
)2/1(
),2
1(,2
1
,
fi
D
DM
MD
D
eA
RA
Df
Df
p
q
A
p
qA
Df
Df
RDf
Df
parameterization:
RD ≠1: Cabbibo suppression
AD ≠0: CPV in decay
AM ≠0: CPV in mixing
≠0 : CPV in interference
B. Golob, Ljubljana Univ. Charm Physics 20 BaBar School, SLAC, Oct 2009
D0 mixing
)%08.036.026.0( A
CP violation
Decays to CP states
0sincos2
)()(
)()(
)()(
)()(
00
00
00
00
CPVno
M
intmix
f
dec
f
CP
xyA
KKDKKD
KKDKKDA
aaa
fDfD
fDfDA
tt
tt
with adec<<1:
)%15.030.001.0( A
Belle, PLB670, 190 (2008), 540fb-1
BaBar, PRD78, 011105 (2008), 384fb-1
t-integrated
ACPmeas =A
+ AFB + ACPf
A : comparison of tagged/untagged
(D*+ →D0+),D0 →K-+
AFB: asymmetric f(cosqCMS)
t-dependent
)%13.034.000.0( KK
CPA
)%11.030.043.0( KK
CPA
Belle, PRL 98,
211803 (2007), 540fb-1
ACPKK ACP
AFBKK AFB
|cosqCMS| |cosqCMS|
|cosqCMS| |cosqCMS|
BaBar, PRL 100,
061803 (2007),
386fb-1
B. Golob, Ljubljana Univ. Charm Physics 21 BaBar School, SLAC, Oct 2009
D0 mixing
CP violation
WS decays (non-CP)
separate D0 and D0 tags;
fit (x’2,y’,RD) → (x’±2, y’±,RD±);
DD
DDD
RR
RRA
AD = (23 ± 47) ·10-3
AM = (670 ± 1200) ·10-3
MM
MMMM
RR
RRA
yxR
2
22
BaBar, PRL 98, 211802 (2007), 384fb-1
Belle, PRL 96, 151801 (2006), 400fb-1
consistent
consistent
consistent with 0
x10-3
t-dependent Dalitz analyses
additional free param, |q/p|, ;
rad
pq
)09.030.028.0
24.0(
09.010.0
29.030.0
86.0/
Belle, PRL 99, 131803 (2007), 540fb-1
B. Golob, Ljubljana Univ. Charm Physics 22 BaBar School, SLAC, Oct 2009
D0 mixing
Average of results K+K-
K+-
KS-+ RM
c2 fit including correlations
among measured quantities
c2/n.d.f.=
26.3/18
http://www.slac.stanford.edu/xorg/hfag/charm/
(x,y)≠(0,0): 10 s;
CP even state heavier and
shorter lived;
no CPV within 1s
CP
V
uncertainty
Don't keep mixing in these
other things. It only confuses.
K. Kinski (1926 - 1991)
n.b.: x(D0) ≈0.01; x(K0) ≈1; x(Bd) ≈ 0.8; x(Bs) ≈ 25;
x (0.98 +0.24 −0.26 )%
(26.4 +9.6 −9.9 )°
y (0.83 ± 0.16)%
Kππ (14.8 +20.2 −22.1 )°
RD (0.337 ± 0.009)%
AD (−2.2 ± 2.4)%
|q/p| 0.87 +0.17 −0.15
(−8.5 +7.4 −7.0 )°
B. Golob, Ljubljana Univ. Charm Physics 23 BaBar School, SLAC, Oct 2009
constraints from mixing
21 NP models considered →17 with useful constraints;
improved existing constraints;
examples:
D0 mixing
E. Golowich et al., PRD76, 095009 (2007)
D0 D0
iLlkRd
~
iLlkRd
~
R couplings
kRdm~
[GeV]
R SUSY:
xD=1.00%±0.25%
constraint
4th generation fermion
mb’
[GeV]
|Vub’Vcb’|
xD=1.00%±0.25%
constraint
Prediction is very difficult,
especially of the future.
N. Bohr (1885 - 1962)
B. Golob, Ljubljana Univ. Charm Physics 24 BaBar School, SLAC, Oct 2009
constraints from mixing
21 NP models considered →17 with useful constraints;
improved existing constraints;
examples:
D0 mixing
E. Golowich et al., PRD76, 095009 (2007)
D0 D0
iLlkRd
~
iLlkRd
~
R couplings
kRdm~
[GeV]
R SUSY:
xD=1.00%±0.25%
constraint
4th generation fermion
mb’
[GeV]
|Vub’Vcb’|
xD=1.00%±0.25%
constraint
xD=1.00%±0.08%
constraint (50 ab-1)
xD=1.00%±0.08%
constraint (50 ab-1)
Prediction is very difficult,
especially of the future.
N. Bohr (1885 - 1962)
B. Golob, Ljubljana Univ. Charm Physics 25 BaBar School, SLAC, Oct 2009
D0 l+l-
another FCNC;
BrSM(D0 m+m-) ~ 10-13
(including long distance contrib.)
(helicity supp., e+e- Br lower)
R SUSY:
Br(D0 m+m-) O(10-8)
Leptoquarks:
explanation of fDs discrepancy (see next slides)
Br(D0 m+m-) ~ 8x10-7
D0 rare decays homework: plot (short dist.) Feynman diagrams
for D0 l+l-
(hint: two amplitudes, one similar to (short dist.)
D0 mixing, other involves )
G. Burdman et al., PRD66, 014009 (2002)
D0 D0 i
l kd~
i2k
i2k i1k
i1k
kd~ i
lc
u
c
u
c
u kd
~ m
m
22k
21k
D0
relation to mixing
(if i=2, i.e. m contrib. in
mixing dominates)
E. Golowich et al., PRD79, 114030 (2009)
I. Dorsner et al., arXiv:0906.5585
B. Golob, Ljubljana Univ. Charm Physics 26 BaBar School, SLAC, Oct 2009
D0 l+l-
absolute Xc Br’s measurement
difficult @ B-factories
(normalization – scc; fragmentation)
relative measurement (D0 +-)
D0 rare decays
D0 +-
D0 m+m-
D0 e+e-
D0 e+m-
signal
region
# signal events,
, Br(D0 +-)
E. Won, EPS09,
http://belle.kek.jp/belle/talks/EPS09/won.pdf
B. Golob, Ljubljana Univ. Charm Physics 27 BaBar School, SLAC, Oct 2009
D0 l+l-
systematic uncertainties
(, misidentification, fit,...) negligible;
L = 1 ab-1 (Belle) + 0.5 ab-1 (BaBar)
BrUL
exp = BrUL L0 / L
> O(100 GeV)
D0 rare decays
dm~
homework: Statistics: when and why does the U.L. scale
with integrated luminosity and when with L ?
B. Golob, Ljubljana Univ. Charm Physics 28 BaBar School, SLAC, Oct 2009
Ds leptonic decays
Ds →mn
Q
q
P+
l+
n
fP
VQq
2
222
22
18
)(
P
PPQqF
SM
m
mmmfV
G
P
n
W+
(H+)
(Ds+ → tn): (Ds
+ → mn): (Ds+ → e+n)=
1:4x10-3:10-7
strategies:
fP |VQq|→ fP from LQCD |VQq|
fP |VQq|→ |VQq| from UT fit fP
H± contrib.;
...
Possible NP:
Exp. difficulties:
n in final state;
(absolute) measurement of Ds Br;
22
2
2
)tan1()()( nnH
PSM
m
mPP ll
B. Golob, Ljubljana Univ. Charm Physics 29 BaBar School, SLAC, Oct 2009
Ds leptonic decays
D
e+ e-
n
Ds
µ
Ds*
tag signal
K
K
additional
particles
Kprim
full recon.
Ds →mn check of LQCD (fP) ?
Method:
inverse (recoil) reconstruction
D → Kn, n=1,3
relative charge (Kprim, D)/Ds*
right-, wrong-sign
inclusive Ds signal
(no m requirement)
efficiency depends on # primary particles:
nX = 3 (DDs*Kprim) + N
differences data/MC
M(Ds)=Mrec(DKprimX) recon. in recoil
M2(n)=M2rec(DKprimXm)
Ds → mn signal
Belle, PRL 100, 241801 (2008), 548fb-1
B. Golob, Ljubljana Univ. Charm Physics 30 BaBar School, SLAC, Oct 2009
Ds leptonic decays Ds →mn Method fit data M(Ds) distr. with MC signal
in bins of nXrec;
bkg. from Wrong-sign
inclusive Ds normalization;
Method fully reconstruct tag side Ds,D
+,D0,D*+;
m,;
pn from pmiss with m(n,m)mDs;
signal in
M=M(mn)-M(mn) (~ mDs*-mDs);
exact Ds production in cc not known
normalization: Ds→
3
8
3
,
10)87.010.32(
i
iMC
Ds
Ds
i
rec
Ds NwN
Ds* →Ds
Ds → N=209399
D
e+ e-
n Ds
µ Ds* tag
Belle, PRL100, 241801 (2008), 548fb-1
BaBar, PRL98, 141801 (2007), 230fb-1
B. Golob, Ljubljana Univ. Charm Physics 31 BaBar School, SLAC, Oct 2009
Ds leptonic decays Ds →mn Signal fit data M(n) distribution with MC signal
in bins of nXrec; bkg. from Ds → en
Belle, PRL100, 241801 (2008), 548fb-1
BaBar, PRL98, 141801 (2007), 230fb-1
Ds* →Ds
Ds → mn N=48955
816169
8
3
,
i
iMC
i
rec NwN m nm n
m nrec
Ds
rec
sN
NDBr
m n
m n
mn )(
Br(Ds → mn) =
(6.44 ± 0.76 ± 0.56) x10-3
Br(Ds →mn) =
(6.74 ± 0.83 ± 0.26 0.66) x10-3
dependence reduced (single track (m) recon.)
last uncertainty Br(Ds →)
fDs = (275 ± 16 ± 12) MeV
using |Vcs| = 0.9730 ± 0.0002 from overall
fit including unitarity (PDG)
fDs = (283 ± 17 ± 7 ± 14) MeV
Belle, PRL100, 241801 (2008), 548fb-1
BaBar, PRL98, 141801 (2007), 230fb-1
B. Golob, Ljubljana Univ. Charm Physics 32 BaBar School, SLAC, Oct 2009
Ds leptonic decays Ds →mn Average of absolute
meas.;
fDs:
huge improvement in LQCD accuracy;
2.1 s difference;
agreement for fD+:
LQCD: 208 ± 4 MeV
exp.: 223 ±17 MeV
(but exp. error larger than for fDs)
HPQCD, UKQCD,
PRL100, 062002 (2008) LQCD
HFAG; http://www.slac.stanford.edu/xorg/hfag/charm/
to do list:
confirm LQCD uncertainty;
reduce exp. uncertainty;
with L=1.5 ab-1
s(Br)/Br 9%
B-factories L=1.5 ab-1
B. Golob, Ljubljana Univ. Charm Physics 33 BaBar School, SLAC, Oct 2009
Spectroscopy
Production
@ B-factories open and hidden
charm;
clean exp. environment;
various methods related
to different prod.
mechanisms;
rich harvest of previously
unknown states at
B-factories;
only one (“exotic”)
example discussed;
spectroscopy:
tests of QCD, bounding
q’s and g’s in hadrons
Vcb
Vcs* B
b c
q
c
s
q
Vcb
Vq1q2*
B
b c
q
q1
q2
q
c
c c
c
* e+
e-
* e+
e- X
e+
e- X
e-
e+
open charm
(Ds**, D**,...) colour suppressed;
hidden charm
(cc, charmonium-like...)
continuum
(double cc)
initial state radiation
(1-- states) two photon processes
B. Golob, Ljubljana Univ. Charm Physics 34 BaBar School, SLAC, Oct 2009
Spectroscopy
Exotic states states other than q1q2, q1q2q3
not forbidden in SM;
exotic JPC (e.g. 0+-, 1-+, 2+-,...
forbidden for qq);
exotic decay modes (not possible
from qq);
strange properties (widths,...);
pentaquarks:
q1q2q3q4q5;
hybrids:
cc + g’s;
tetraquarks:
diquark-antidiquark, [cq][cq]
molecules:
M(cq)M(cq), loosely bound
mesons
...Life is like a box of chocolates, you never know...:
Forrest Gump (1994)
B. Golob, Ljubljana Univ. Charm Physics 35 BaBar School, SLAC, Oct 2009
Spectroscopy
Z+(4430) B →(y’+)K;
y’ →ll, J/y;
Dalitz plot;
fit with Z+
& set of K*’s
M(y’+);
Z+(4430) signif.:
6.4 s
Belle, PRL100, 142001 (2008), 605 fb-1
Vcb
Vcs* B-
b c
u
c
s
u
d
d
d K0
[cu][cd] Z-
s
K*’s only
K*’s & Z+
MeVZ
MeVZM
)107()(
)4443()(
5674
14386
1319
1215
B. Golob, Ljubljana Univ. Charm Physics 36 BaBar School, SLAC, Oct 2009
Spectroscopy
Z+(4430) B →(y’+)K;
detailed study by BaBar; angular distribution
of K vs. mK → description of mY (reflections);
satisfactory description (no need for Z+)
fit with K background and single resonance;
no stat. significant signal;
Belle/BaBar data not inconsistent run:
const int N_Bfact= 2; bool Found_It[N_Bfact]; string Balle=“BaBar Belle”; string::const_iterator ci; int i; for(ci=Balle.begin(); ci!=Balle.end(); ci++) { if(ci.findZ().fullL()) { cout<< “Z found in” << ci << endl; Found_It[i] = true; i++; } } if{Found_It[1] && Found_It[2]} cout<< “new form of matter found”;
residuals
ho
me
wo
rk:
Com
pile
the c
ode
B. Golob, Ljubljana Univ. Charm Physics 37 BaBar School, SLAC, Oct 2009
Summary
Main experimental issues
Mixing and CPV
CP eigenstates
good S/N (tagged decays)
precise modelling of decay-t
resolution needed
WS hadronic decays
signif. background in WS;
accurate resol. f. param.;
stat. issues for x’2<0;
t-dependent Dalitz
model system.;
direct meas. x, y;
any f = f: sensitivity to x depending on
apriori unknow strong phase variation
CPV:
accurate estimate of detector
induced asymmetries
D0 l+l-
accurate description of reflection
statistically limited
Ds mn
method to perform absolute Br
measurement
with further work on syst. uncertainties
a measurement competitive to Cleo-c
possible
Spectroscopy
large number of “exotic” signals,
various methods
Dalitz analyses
Charm is... a way of getting the
answer yes without having asked
any clear question. A. Camus (1913 - 1960)
B. Golob, Ljubljana Univ. Charm Physics 38 BaBar School, SLAC, Oct 2009
Summary
• D mixing and CPV, as well as some rare decays,
are a unique handle to test FCNC of u-like quarks
• Leptonic D(s) decays: tests show hints of discrepancy
(Dr. Jeckyll/Mr. Hyde)
• Important constraints on NP models from existing results
(yet to be fully confronted with other experimental constraints)
• Spectroscopy...may need extensions
• B-factories have not yet spoken the final word
(only part of possible measurements done)
• Super-B factory is clearly motivated also by charm physics
e.g. s(x,y) 5x10-4, s(ACP ~ x sin, AM y cos) 5x10-4
(possible evidence for NP)
B. Golob, Ljubljana Univ. Charm Physics 39 BaBar School, SLAC, Oct 2009
Summary
there may be hidden treasures in charm physics....
B. Golob, Ljubljana Univ. Charm Physics 40 BaBar School, SLAC, Oct 2009
Summary
there may be hidden treasures in charm physics....
B. Golob, Ljubljana Univ. Charm Physics 41 BaBar School, SLAC, Oct 2009
Bonus material
B. Golob, Ljubljana Univ. Charm Physics 42 BaBar School, SLAC, Oct 2009
D0 mixing
History observation of K0:
1950 (Caletch)
mixing in K0:
1956 (Columbia)
observation of Bd0:
1983 (CESR)
mixing in Bd0:
1987 (Desy)
observation of Bs0:
1992 (LEP)
mixing in Bs0:
2006 (Fermilab)
observation of D0:
1976 (SLAC)
mixing in D0:
2007 (KEK, SLAC)
(evidence of)
6
years
4
years
14
years
31
years
c quark
mass
t quark
mass
????
????
B. Golob, Ljubljana Univ. Charm Physics 43 BaBar School, SLAC, Oct 2009
D0 mixing more
Time evolution
diagonal elem.: P0 P0
(including decays)
non-diagonal elem.: P0 P0
P0
q2 q1
P0
P0 = K0, Bd0, Bs
0 and D0
flavour states ≠ Heff eigenstates:
(defined flavour) (defined m1,2 and 1,2)
00
2,1 PqPpP
eigenvalues:
q
p
q
p
iMiM
iMiM
2,1*
12*
12
1212
22
22
),(2
1212
2,1
2,12,1
Mfim
)(4
2||4
2*
1212
2
122
12
2
2
Mm
Mm2121 , mmm
q1 q2
B. Golob, Ljubljana Univ. Charm Physics 44 BaBar School, SLAC, Oct 2009
D0 mixing
Phenomenology only P0 system with down-quarks in loop;
D0 mixing FCNC of uplike quarks
|VcbVub*|<< |VcsVus*|, |VcdVud*|
assuming unitarity in 2 generations
222**
00
)( dsudcdcsus
wk
mmVVVV
DHD
0
55
0
2
222**
2
2020 |)1()1(|
)(
4DcucuD
m
mmVVVV
GDHD
c
dsusudcdcs
FC
w
m
m
more precisely:
G. Burdman, I. Shipsey,
Ann.Rev.Nucl.Sci. 53, 431 (2003) DCS SU(3) breaking
;)2
(1
2;)
2(
2 1212
211212
21
iM
p
qyiM
p
qmmx
mixing parameters:
B. Golob, Ljubljana Univ. Charm Physics 45 BaBar School, SLAC, Oct 2009
D0 mixing
Phenomenology
if mi = mj due to CKM unitarity:
no mixing
P0-P0 transition → box diagram at quark level
),,( 2
,,,
22**
00
j
tcuji
iWujcjciui
wk
mmmVVVV
DHD
F
loop int., CKM unitarity
P0: any pseudo-scalar meson;
specific example of D0
c
u
u
c
d, s, b
d, s, b
W+ W- D0 D0
c
u
u
c
d, s, b d, s, b
W+
W-
D0 D0
Vci
Vcj
Vuj*
Vui*
j
bsdji
iujcjciuiwk mmVVVVDHD
,,,
**00
)(),,( 23
22
21
20
222 WjijiWjiW mOmmfmfmfmfmmmF
simplified treatment based on dimension:
O. Nachmtann, Elem. Part. Phys., Springer-Verlag
A.J. Buras et al., Nucl.Phys.B245, 369 (1984) for serious treatment see e.g.:
B. Golob, Ljubljana Univ. Charm Physics 46 BaBar School, SLAC, Oct 2009
D0 mixing more
Time evolution
)sin(2)sinh(2
)cos()cosh(
)(1
**
22
22
0
xtAAp
qytAA
p
q
xtAp
qAytA
p
qA
dt
fPd
e
ffff
ffff
t
;2
; 2121
y
mmx
for easier notation:
t → t
decay rates:
Decay time distribution of experimentally accessible states P0, P0
sensitive to mixing parameters x and y,
P1,2 evolve in time according to m1,2 and 1,2: )0()( 2,12,12,1
tPetP
ti
00
2,1 PqPpP |P0(t)>, |P0(t)>
D. Kirkby, Y. Nir, CPV in Meson Decays, in RPP
B. Golob, Ljubljana Univ. Charm Physics 47 BaBar School, SLAC, Oct 2009
D0 mixing more
CPV parameterization three types of CPV
iM
i
D
D
f
fiDD
f
f
iDD
f
fi
D
D
f
f
D
f
f
D
f
f
D
f
f
eA
p
q
eA
R
A
Ae
AR
A
A
eA
RA
Ae
A
R
A
A
A
A
A
RA
AR
A
A
)2
1(
21
;)2
1(
)2
1(;
21
21
;
*
*
*
*
RD ≠1 Cabbibo supp.
AD≠ 0direct CPV
AM≠ 0CPV in mixing
≠ 0CPV in interf.
- sign due
to relative sign of
Vus and Vcd;
22
2
22
*
*
)1(
)1)(1(
csud
uscd
f
f
VV
VV
A
A
B. Golob, Ljubljana Univ. Charm Physics 48 BaBar School, SLAC, Oct 2009
D0 mixing more
Decays to CP eigenstates D0 → K+K- / +-
222
22
2
20
222
2
22
20
4)1(
1cossin
)1)(1(
1
)1(
1)(
4)1(
)1(cossin
1
11
)(
1;;;
tyx
Atyx
AAAA
e
tPf
tyx
A
Atyx
A
AA
e
tPf
AA
AAAAAff
MMDD
ft
D
M
D
Mft
D
f
f
ffff
tyxAAAAe
tPf
tyxAAAe
tPf
MDDft
DMft
cossin)1(21)(
)cossin)(1(1)(
2
20
2
20
to linear order:
B. Golob, Ljubljana Univ. Charm Physics 49 BaBar School, SLAC, Oct 2009
D0 mixing more Decays to CP eigenstates
D0 → K+K- / +-
since AD<<1
tytyt
CP
t
CPfMftt
CPCP eeetyetPftPf
tyAtxAyAe
tPf
e
tPf
)1(2
02
0
22
20
20
)1()()(
]1[)sincos(1)()(
txAyAAAe
tPf
e
tPf
MDDftt sincos)1(1
)()( 2
20
20
if same procedure applied separately to D0 and D0 lifetime:
1/tf=t/(1+yCP); yCP=(t/tf)-1=y cos-Amx sin
tt
tt
tttt
sincossin)1(cos
)cossin)(1(1,)cossin)(1(1
xyAxAyAA
yxAAyxAA
MDM
ff
ff
DMfDMf
B. Golob, Ljubljana Univ. Charm Physics 50 BaBar School, SLAC, Oct 2009
D0 mixing Decays to CP eigenstates
D0 → K+K- / +-
back
Fit
simultaneous binned likelihood fit to
K+K- /K-+/+- decay-t, common free yCP
)(')'(/' tBdttteN
dt
dN t Rt
t
R : ideally each si Gaussian resol. term
with fraction fi;
: described by 3 Gaussians
N
i k
ikki tsttGwftt1
3
1
0 ),,'()'( sR
t = 408.7±0.6 fs
event-by-event st
parameters of R depend slightly
on data taking conditions
trec-tgen/st
K-+
Belle, PRL 98, 211803 (2007), 540fb-1
B. Golob, Ljubljana Univ. Charm Physics 51 BaBar School, SLAC, Oct 2009
D0 mixing more
CP eigenstates CPV t-integrated CPV in D0 → K+K- / +-
A from comparison Auntag/Atag
=0
(strong int.) =0
(same for D0, D0)
BaBar, PRL 100, 061803 (2007), 386fb-1
method of
B. Golob, Ljubljana Univ. Charm Physics 52 BaBar School, SLAC, Oct 2009
D0 mixing more
CP eigenstates CPV t-integrated CPV in D0 → K+K- / +-
A (p,cosq)
Belle, PLB670, 190 (2008), 540fb-1
B. Golob, Ljubljana Univ. Charm Physics 53 BaBar School, SLAC, Oct 2009
D0 mixing more t-dependent Dalitz analyses
Dalitz model;
Belle, PRL 99, 131803 (2007), 540fb-1
M signal
rnd slow
combin.
13 BW resonances, non-resonant contr.;
comb. bkg.: from M sideband
NRr i
NR
i
r eammBeamm
),(),( 2222A
test of S-wave contr. (f0, s1,2):
K-matrix formalism
Results (fit fractions, phases) in
agreement with
(measurement of 3)
Belle, PRD73, 112009 (2006)
B. Golob, Ljubljana Univ. Charm Physics 54 BaBar School, SLAC, Oct 2009
D0 mixing more
t-dependent Dalitz systematics Belle, PRL 99, 131803 (2007), 540fb-1
Largest
systematics
model dependence [10-4]:
x y
-10.3 +0.1 K*0(1430) DCS/CF -15%
+ 6.9 -2.5 K*2(1430) DCS/CF -30%
-1.6 -0.9 K*(1410) DCS & CF -20%
-5.1 -4.1 (q2) const.
---------------------------------
+10 +6 Total model dep.
-14 -8
experimental:
x y
+7.6 -7.8 p* variation
-5.6 -5.7 Dalitz pdf for bkg. from
different t bins
-----------------------
+9 +8 Total experimental
-7 -12
ob
se
rve
d d
iscre
pa
ncy
from
inp
ut in
MC
statistical
uncertainty:
s(x)=29x10-4
s(y)=24x10-4
B. Golob, Ljubljana Univ. Charm Physics 55 BaBar School, SLAC, Oct 2009
D0 mixing more
t-dependent Dalitz analyses
Belle, PRL 99, 131803 (2007), 540fb-1
efficiency and resol. in M(
rnd s bkg.:
Prnd [(1-fw) M(m-2,m+
2,t) +fw M(m+2,m-
2,t)] R(t)
fw from fit to Q side band: fw= 0.452 ± 0.005
diff. w.r.t. fw=0.5 in systematic error
comb. bkg.:
Pcmb B(m-2,m+
2) * ([ (t) + Exp(t) ]R’(t)
parameters from fit to Dalitz and t distrib. of M(KS +- ) sideband
(systematics: Dalitz distrib. in different t intervals)
B. Golob, Ljubljana Univ. Charm Physics 56 BaBar School, SLAC, Oct 2009
D0 mixing Constraints on NP
SuperB, L = 5 ab-1
E. Golowich et al., PRD76, 095009 (2007)
x
x=2%
’12k’11k
GeVdmkR 300)
~(
TeVdmkR 1)
~(
D0 D0
iLl~
iLl~kRd
kRd
D0 D0
iLlkRd
~
iLlkRd
~
uncertain SM predictions for x, y;
measured values can impose constraints
on NP models parameter space;
e.g. R-parity violating SUSY;
existing constraints largely improved for
many NP models
R-parity violating
coupling const.
Approximate sensitivity
s(x) s(y) s(|q/p|) s()
0.1% 0.1% 0.1 0.1
LHCb, L = 10 fb-1
s(x’2) s(y’)
6x10-5 0.1%
x, y accuracy ~3x better than current WA;
sensitivity to CPV would cover range of
SM predictions
Prediction is very difficult,
especially of the future.
N. Bohr (1885 - 1962)
B. Golob, Ljubljana Univ. Charm Physics 57 BaBar School, SLAC, Oct 2009
D0 mixing from CLEO-c
y(3770) →D0D0
at threshold D0D0 in C=-1 state
effective Br’s depending on
mixing param.:
y, RM=(x2+y2)/2, RDcos
S±: CP eigenstates
e-: Xen
fit to set of single and double Br’s
Br(D0D0 →fi/fj)
Br(D0 →fi)Br(D0 →fj)
Br(D0D0 →fiX)
Br(D0 →fi)
single D0
reconstr.
both D0
reconstr. )1(
)1(
)(
)(),(
2
2
221
yBrBry
eDBr
eDBreDSDBr
eSS
S
measured from ST rates
uncorrelated
production
uncorrelated
production
Cleo-c, PRD78, 012001 (2008), 281pb-1
(RWS=(K+-)/(K-+))
B. Golob, Ljubljana Univ. Charm Physics 58 BaBar School, SLAC, Oct 2009
D0 mixing from CLEO-c
0 1 2 3 4 5 [rad]
y’=
yco
s-x
sin
[%
] 1.0
0.5
0
-0.5
-1.0
y’ measured
m
easure
d
y(3770) →D0D0
constraints
average
direct meas.
(fit w/o external input)
0 1 2 3 4 5 [rad]
cos
1
0
-1
B. Golob, Ljubljana Univ. Charm Physics 59 BaBar School, SLAC, Oct 2009
Ds leptonic decays more Ds →mn projection
B factories with 2 ab-1
~4% uncertainty on fDs;
Charm-factory: syst. on Ds tags?
combined: test of LQCD to ~2-3%;
possible NP effects:
Cleo-c
Ds tags, 2.5%
L / fb-1 0.5 1.0 1.5 2.0
Cleo-c, PRD 76, 072002 (2007)
%5.1/
%1.7)(
0
LLf
f
Ds
Dss
Belle, PRL100,
241801 (2008), 548fb-1
M: NP mass
B.A. Dobrescu, A.S. Kronfeld,,
PRL100, 241802 (2008)
B. Golob, Ljubljana Univ. Charm Physics 60 BaBar School, SLAC, Oct 2009
Spectroscopy
X(3872)
observed in B decays,
B →(J/y)K; charmonium-like;
well established state;
Vcb
Vcs* B
b c
q
c
s
q
K
Belle, PRL 91,
262001 (2003), 140fb-1
Mbc in 5 MeV bins
of M(+-J/y)
Belle,
hep-ex/0505038,
250fb-1 MeV
MeVMMM
MeVM
DDX
X
3.2
6.06.0
5.02.3871
00*)3872(
)3872(
B. Golob, Ljubljana Univ. Charm Physics 61 BaBar School, SLAC, Oct 2009
MD+MD*
c’
J/y
c
cc0
cc1
cc2
y’ y”
hc
c”
hc’
cc1’
c2
y2 y3
Spectroscopy
X(3872)
properties
C=+1;
M() distrib., r-like;
(cc) →J/yr isospin breaking;
4-quark states:
c’’: ang. distr., M, ;
cc0’: ang. distr., DD;
cc1’: J/y
c2: c dominant, DD*;
cc2’: DD*;
no obvious cc candidate;
05.014.0)/(
)/(
y
y
JXBr
JXBr
102
1
)(2
1)(
2
1
2
1
II
dduudduucc
uucccc2’
CDF, PRL96, 1
02002 (2006), 360pb-1
Belle, hep-ex/0505037, 250fb-1
Belle,
hep-ex/0505038,
250fb-1
ang. distrib.:
JPC= 1++, 2-+ favoured;
more
isospin breaking
B. Golob, Ljubljana Univ. Charm Physics 62 BaBar School, SLAC, Oct 2009
Spectroscopy
X(3872)
other possibilities
DD* molecule:
isospin breaking;
JPC=1++;
J/y favoured over DD;
exp. ratio ~ 0.1
E. Braten, M. Lu, PRD77, 014029 (2008);
see also E.S. Swanson, Phys. Rept. 429, 243 (2006)
for review
B+→ X(D0D00)K+
B+→ X(D*0D0)K+
MeVM X )9.07.04.3875(7.14.0
)3872(
MeVM X )5.01.3875(5.07.0
)3872(
last uncertainty: mD0;
main syst.: 0 calibration and signal shape
Belle, PRL97, 162002 (2006), 414 fb-1
BaBar, PRD77, 111102 (2008), 347 fb-1 410)/(
)( 000
y
JXBr
DDXBrR
Belle, PRL97, 162002 (2006), 414 fb-1
Belle, hep-ex/0505037, 250fb-1
J=2 decays to DD*
suppressed by (p*)2L+1
with L=1,2;
1++ state favoured
more
B. Golob, Ljubljana Univ. Charm Physics 63 BaBar School, SLAC, Oct 2009
Spectroscopy
X(3872)
other possibilities
DD* molecule:
prod. from B0 suppressed
compared to B+
(depending on model parameters);
tetraquarks: two mixed states,
[cu][cu], [cd][cd];
one produced mainly in B0,
other in B+ decays mass
difference;
also charged X+ [cu][cd],
no evidence so far;
Belle,
BELLE-CONF-0711,
605 fb-1
BaBar,
PRD77, 111101 (2008),
413 fb-1
M(J/y)
for B →XK K+
Ks
Ks
K+
MeVXBMXBM
XKBBr
XKBBr
)27.090.022.0()()(
10.024.094.0)(
)(
0
00
MeVXBMXBM
XKBBr
XKBBr
)4.06.17.2()()(
05.024.041.0)(
)(
0
00
L. Maiani et al., PRD71, 014028 (2005)
It is characteristic of wisdom
not to do desperate things.
H.D. Thoreau (1817 - 1862)
B. Golob, Ljubljana Univ. Charm Physics 64 BaBar School, SLAC, Oct 2009
Spectroscopy more
X(3872)
B →KX (J/y):
B →Kcc1(J/y) calibration;
B →KX (J/y):
B →Ky2S calibration;
B →KX (J/y0):
13.6±4.4 evts.(4s)
no. of B’s in bins of M(J/y)
Belle, hep-ex/0505037, 250fb-1
Belle,
BELLE-CONF-0711,
605 fb-1 no. of B’s in bins of M(0)
13.1±4.2 evts.(6.4s)
M(+-0)>750 MeV
3.04.00.1)/(
)/( 0
y
y
JXBr
JXBr
Belle, hep-ex/0505037, 250fb-1
B. Golob, Ljubljana Univ. Charm Physics 65 BaBar School, SLAC, Oct 2009
Spectroscopy more
X(3872)
tetraquarks:
predicted spectrum;
mass difference;
q: mixing angle
DD* molecule:
wave function fractions
MeVXMXM lhcos
27)()(
L. Maiani et al., PRD71, 014028 (2005)
back
410)/(
)( 000
y
JXBr
DDXBrR
E.S.Swanson, PLB588, 189 (2004)
Zi
binding energy
B. Golob, Ljubljana Univ. Charm Physics 66 BaBar School, SLAC, Oct 2009
Spectroscopy
Z+(4430)
B →(y’+)K;
y’ →ll, J/y;
Dalitz plot;
K* veto;
M(y’+);
fit: BW + phase space;
signal stable in subsamples,
w.r.t. K* veto, etc.;
known S-, P- and D-wave K
resonances tried, cannot
reproduce the peak;
first charged charmonium-like
resonance;
Belle, PRL100, 142001 (2008), 605 fb-1
MeVZ
MeVZM
)45()(
)244433()(
1330
1318
N=121 ± 30
6.5 s
possibilities:
tetraquark, radial excitation of X+(3872)
(JP=1+; neutral partner?);
D*D1(2420) threshold effect;
D*D1(2420) molecule
(JP=0-,1-,2-;decays to D*D*?)
L.Maiani et al., arxiv:0708.3997
J. Rosner, PRD74, 114002 (2007)
C. Meng et al., arxiv:0708.4222
B. Golob, Ljubljana Univ. Charm Physics 67 BaBar School, SLAC, Oct 2009
Spectroscopy more
Z+(4430)
S-, P-, D-wave interference: y’
K
q
16 GeV2
22 GeV2
M2(
y’)
+1.0
-1.0
co
sq
0.25 (4.43)2
GeV2
inte
rfere
nce
incoherent
cannot produce
a single peak
at cosq ~ 0.25
Belle, PRL100, 142001 (2008), 605 fb-1
B. Golob, Ljubljana Univ. Charm Physics 68 BaBar School, SLAC, Oct 2009
SuperB more
back
energy frontier sesnitivity frontier
not to underestimate power of
precision measurements
Two approaches
Competitiveness
A. Roodman, JPS/DPF meeting, Hawaii 06
B. Golob, Ljubljana Univ. Charm Physics 69 BaBar School, SLAC, Oct 2009
SuperB more 2
tree dominated
2
penguin dominated
NP
NP
Some physics motivation
different models for NP;
precise meas. of various
observables test
specifically for this mode:
SM expect. for sin21: 0 ± 2%
current sens.: 6% (b →sqq)
current lum.: 1.2 ab-1
needed: >10 ab-1
50ab-1 ΔS=0.23
B0→J/ψK0
B0→ K0
B. Golob, Ljubljana Univ. Charm Physics 70 BaBar School, SLAC, Oct 2009
SuperB more Sensitivity
preliminary/
under construction !
B. Golob, Ljubljana Univ. Charm Physics 71 BaBar School, SLAC, Oct 2009
SuperB more Sensitivity
preliminary/
under construction !
B. Golob, Ljubljana Univ. Charm Physics 72 BaBar School, SLAC, Oct 2009
SuperB more
More examples of physics
motivation
Complementarity
Super KEKB Physics
working group
B. Golob, Ljubljana Univ. Charm Physics 73 BaBar School, SLAC, Oct 2009
SuperB more Proposed luminosity
Much smaller βy*
6.5(LER)/5.9(HER) → 0.21/0.37
Slightly increase beam currents
1.8A(LER)/1.45A(HER) → 3.6A/2.1A
Keep ξy
0.1(LER)/0.06(HER) → 0.09/0.09
LoI for SuperKEKB (2004)
Slightly smaller βy*
6.5(LER)/5.9(HER) → 3.0/6.0
Significantly increase beam currents
1.8A(LER)/1.45A(HER) → 9.4A/4.1A
Increase ξy
0.1(LER)/0.06(HER) → 0.3 or more
Proposed by P. Raimondi et al.
Decision expected in 2009
Target luminosity: 8×1035/cm2/s;
Continuous injection (succesful
experience of KEKB operation);
Options:
- High current
- Nano-beam
B. Golob, Ljubljana Univ. Charm Physics 74 BaBar School, SLAC, Oct 2009
SuperB more Proposed luminosity
KEKB
design
KEKB achieved
(with crab)
SuperKEKB
High-Current
SuperKEKB
Nano-Beam
y* (mm) 10 / 10
6.5 / 5.9
(5.9 / 5.9) 3 / 6 0.26 / 0.26
x (nm) 18 / 18 18(15) / 24 24 / 18 2.8 / 2.0
sy(mm) 1.9 1.1 0.85 / 0.73 0.084 / 0.072
xy 0.052 0.108 / 0.056
(0.101 / 0.096) 0.3 / 0.51 0.08 / 0.08
sz (mm) 4 ~ 7 5 / 3 5 / 5
Ibeam (A) 2.6 / 1.1 1.8 / 1.45
(1.62 / 1.15) 9.4 / 4.1 3.6 / 2.1
Nbunches 5000 ~ 1500 5000 ~ 2000
Luminosity
(1034 cm-2 s-1) 1
1.76
(2.08) 53 80
B. Golob, Ljubljana Univ. Charm Physics 75 BaBar School, SLAC, Oct 2009
SuperB more Proposed luminosity
Redesign the HER arcs to
reduce the emitance.
Two separate focusing
quads/each 2 beams
closer to IP;
Superconducting /
permanent magnets
New positron target /
capture section
Replace long dipoles
with shorter ones in HER.
Low emittance positrons
HER e+ 3.7 A
Low emittance gun
More RF /
modify RF systems.
Belle II
LER e– 2.1 A
B. Golob, Ljubljana Univ. Charm Physics 76 BaBar School, SLAC, Oct 2009
Belle 2 more Higher background
radiation damage and occupancies
fake hits and pile-up noise in the ECL Improve performance
try better PID options
low p μ identification for b → sμμ efficiency
hermeticity → missing E “reconstruction”
Higher event rate
higher rate trigger, DAQ and computing
BELLE
BELLE-II
SC solenoid
1.5T
New DAQ and
computing
systems
CsI(Tl) 16X0
→ pure CsI (endcap)
Aerogel Cherenkov counter + TOF counter → “TOP” + Aerogel RICH
Si vtx. det. 4 lyr. DSSD → 2 DEPFET pixel lyrs. + 4 lyr. DSSD
CDC: Tracking + dE/dx → small cell + He/C2H6
remove inner lyrs.
m/KL detection
14/15 lyr. RPC+Fe
→ scintillator (endcap)
B. Golob, Ljubljana Univ. Charm Physics 77 BaBar School, SLAC, Oct 2009
SuperB more A. Suzuki, KEK Director General, Inaugural meeting of Super Belle