Transcript Das BELLE Experiment • Das Experiment B-Physik • Überblick über neueste Resultate

Das BELLE Experiment
Gerhard LEDER
Hephy ÖAW-Wien
Mt. Tsukuba
KEKB
Belle
KEK 高エネルギ
Tokyo 東京
~1 km in diameter
• Das Experiment
• B-Physik
• Überblick über neueste Resultate
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
KEKB Collider
Lpeak=1.4 x1034cm-2sec-1
design=1034cm-2sec
BB
threshold
e8GeV
e+
3.5GeV
bg = 0.425
B-Factory
(on the 4s resonance)
BB
threshold
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
Kontinuierliche Injection
Kein Grund, Run zu unterbrechen [CERN courier Jan/Feb 2004]
Immer bei ~max. Strömen, Luminosität both KEKB & PEP-II
~30% more  L dt
normal injection (old)
continuous injection (new)
HER current
LER current
Luminosity
0
~1 fb-1/day !
6 BB)
(~1x10
12
24
Time
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
Der BELLE Detektor
SVD
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
Unterschied SVD1.6 und SVD2.0
Rbeampipe
Rbeampipe
15 mm
20 mm
Rlayer 1
20 mm
Rlayer 1
30 mm
Routside
88 mm
Routside
60 mm
8+10+14=32
Ladders
6+12+18+18=54
SVD1
SVD2
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
Ladders
Wiener R/O & Trigger Elektronik
R-Z Trigger
R-PHI Trigger
2 x 18 FADCTF
24 input
OR and
analog signal
input from
VATA
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
B Zerfälle und das Standard Modell
Quark level
Electro-weak
Vud Vub*  (a)
2
3(g)
1(b)
*
Vcd Vcb
Hadrons
Final state
Vtd Vtb*
QCD/Lattice
New Resonances
b-quark: Heavy  variety of decay modes
Reiches Feld für fundamentale SM Parameter
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
B Zerfälle und “Neue” Physik
Experimental
measurements
agree?
SM predictions
Yes
Deeper understanding
No
New Physics ?
Key point: ANP ~ ASM (small/forbidden)
Penguin
b
W
t
s,d
g,g,Z
+
b
x
s,d
New particle, Phase
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
Prozedur, um B Signal zu extrahieren
Verwende spezielle Kinematik des Y(4S)
Two almost independent variables MB and
DE can be used to select B meson signal:
MB =
* )2 – (S Pi)2
(Ebeam
DE = SEi - Ebeam
*
Methods to extract B signal yield:
1) Cut on MB and fit to DE
2) Cut on DE and fit to MB
3) Double dimensional fit to
MB and DE distribution
4) If B->P1P2P3: cut DE and MB
box and look at resonant
structures in M(P1P2) mass
distribution.
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
Continuums Unterdrückung
Dominanter Untergrund für seltene Zerfälle:
e+e-  qq “continuum”
(~3x BB)
Continuum
Jet-like
qq
e-
e+
To suppress:
use event shape variables
Other
B
continuum
Y (4S)
-
BB
e+
BB
sphärisch
Signal
B
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
e-
Continuums Unterdrückung
To separate spherical BB events
from jet-like continuum
events, topological variables
are used:
1) Second Fox-Wolfram moment
2) Super Fox-Wolfram
(six modified Fox-Wolfram
moments, Fisher discriminant)
3) Angle between B meson and
beam axis direction
4) Angle between thrusts of
selected B meson particles and
all other particles in event
Likelihood ratio includes all info.
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
Die Standard Modell Physik bei BELLE
CKM-Matrix
d
u
c
t
Vud
Vcd
Vtd
s
Vus
Vcs
Vts
{i=1,k=3}: Vub*Vud+Vcb*Vcd+Vtb*Vtd =
b
0
Vub*Vud + 1 + Vtb*Vtd = 0

Vcb*Vcd
Vcb*Vcd
Vub
Vcb
Vtb
-(rih)
-(1-r-ih)
selbstkonsistent falls SM korrekt
B0->ππ
B0->rπ
B0->
D*π
B0->D*r
B->DCPK
rih
rih Unitaritäts Dreieck
Vub*Vud
Vcb*Vcd
0
3(g)
2
Vtb*Vtd
Vcb*Vcd
(a)
1
(b)
1
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
B0->J/Ks
B0->Ks
B0->D(*) D(*)
Direkte CP-Verletzung:B  Kp/pp

Vus/d
b
B
0
d
d
_ _
s/d
W
u
Vub
u
d
K/p+
p-
b
B 0d
Vtb
W
t

Vts/d
g
s/d
+
K/p
u
u
d
d
p-
Tree
Penguin
• Simplest charmless rare decay modes
• Tree - Penguin interference  Direct CP Violation
_ _
Key prediction of
Kobayashi-Maskawa model
Understanding of Penguin
G(B f ) - G(B f )
_ _
ACP =
G(B f )  G(B f )
Anomaly (New Physics)
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
ACP(B0  Kp-)
275M BB
Neu
_
B0 K-p
B0 Kp-
Signal:
2139 53
[submitted to PRL]
ACP = -0.101  0.025  0.005
3.9s significance
[PID efficiency bias correction: dA = -0.01  0.004]
Evidenz für DCPV bei Belle auch bei [A(pp-) 3.2s]
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
Time-Dependent CP Asymmetry
•The CP violation manifests itself in proper-time
difference distributions of two B meson decays.
•The time-dependent CP asymmetry ACP is:
ACP (t ) 
G
G
0
B  fCP
0
B  fCP
(t ) - G B0  f (t )
CP
(t )  G B0  f (t )
S
2Im( )
2
 1
CP
 S sin Dmd t  A cos Dmd t
•Standard Model prediction:
 e
2
, A
-2iM
 -1
2
 1
A( B 
A( B 
Sccs = sin21,
Ssss = sin21,
( -C)
fCP )
fCP )
Accs = 0
Asss = small
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
Prinzip der Messung
e-: 8.0 GeV e
e: 3.5 GeV
(4S)
bg ~ 0.425
Flavor tag
•
•
•
•
BCP
e
fCP (J/K0)
Dz  cbgtB ~ 200 m m
Btag
Dz
Dz
c( bg ) 
Rekonstruiere B  J/K0 Zerfälle
Messe Eigenzeit Differenz: Dt
Bestimme flavor von Btag
Berechne CP Asymmetry aus beiden Dt Verteilungen
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
Dt
Prinzip der 1-Messung mit B  J/ Ks
Flavor-tag decay
(B0 or B0 ?)
J/
e
fCP
e-
t=0
B-B
B+B
KS
Dz
more B’s
more B’s
t  Dz/(cβγ)
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
sin21 mit 152106 BB Paaren
K. Abe et al. [Belle collaboration], BELLE-CONF-0436.
4347 signal events @ 152106 BB
sin 21  0.728  0.056  0.023
poor flavor tag
  1.007  0.041  0.033
consistent with no direct CPV
good flavor tag
Decay modes used:
• J/KS(pp-), J/KS(2p0), (2S)KS,
cc1KS, hcKS
• J/K*(KSp0)
• J/KL
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
Lebensdauer und Mixing mit
Parameter fit results
(with new detector only)
neuem Detektor
Belle preliminary
t B0
t B
Voriger Detektor
(152106 BB)
t B0
[ps]
t B
[ps]
Dmd
[ps-1]
Dmd
Neuer Detektor
(122106 BB)
1.534  0.008  0.010 1.518  0.012
1.635  0.011  0.011
1.652  0.014
0.511  0.005  0.006 0.516  0.007
Previous data sets and fitting function for them are unchanged.
New detector resolution is well understood.
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
•Indirect CP Violation : Mixing und/oder
•Tree - Penguin interference
sin2 (bgsqq) = 0.41  0.07
1
sin21(bgccs) = 0.726  0.037
B0
Vc
b
J/

KS
2
V*
td
B0 V*
td
V
tb
CP violation “same” as J/Ks
within the Standard Model (SM)
Penguin~O(2), Tree~O(4)
deviation = O(1)%
Vtb
V*
td
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
B0Vc
J/
b
KS
B0   K0
[hep-ex/0409049]
275M BB
KS
Nsig=139 14
purity 0.63
KL
Nsig= 36 15
purity 0.17
pB*
includes Ks  p0po
(Nsig=13 5)
Similar to J/KL recon.
+ sophisticated continuum
suppression
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
[hep-ex/0409049]
B → K0 CPV Resultat
S = 0.736
fit
Poor tags
Good tags
KS + KL : S (K0) = +0.06 ±0.33 ±0.09
A (K0) = +0.08 ±0.22 ±0.09
“sin21” ~2.2s away from SM
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
275M BB
BABAR Resultate für B0  K0
BABAR
227M BB pairs
K S0
114  12 events
B   K S 0  0.29  0.31
K
0
0
S
S
B 0   K L0
K L0
98  18 events
S K 0  -1.05  0.51
L
-
-hCP  S K 0  0.50  0.25 0.07
-0.04
C K 0  0.00  0.23  0.05
BABAR-CONF 04/033
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
B0 → wKS & f0(980)KS
wKS Nsig=31 7
f0(980)KS
Nsig=102 18
purity 0.58
purity 0.56
Raw Asymmetry
S = 0.736
fit
Good tags
(~0s @SM)
S = +0.75 0.64  0.13
0.16
A = 0.26 0.48 0.15
New modes !
“sin21”
Good tags
(~2.9s @SM)
-S = -0.47 0.41 0.08
A = -0.39 0.27 0.08
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
sin21 from bgs penguins at FPCP04
sin21(bgsqq) = 0.41  0.07
sin21(bgccs) = 0.726  0.037 CL = 0.00012 (3.8s)
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
„Neue“ Physik bei B   K0 ?
• B   Ks theoretisch verstanden
• A = 0.08 ± 0.22 ± 0.09
•  sin21eff = 0.06 ± 0.22 ±0.09
• 2,2 s Abweichung von „SM“
sin21(bgsqq) = 0.41  0.07
sin21(bgccs) = 0.726  0.037
CL = 0.00012 (3.8s)
SM predicts same CPV
in b  ccs and sqq.
SM penguin
New physics may deviate
CPV in b  ccs from sqq
New process with different CP
phase
+
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004

Zukünftige Untersuchungen:
Radiative and EW Penguins
b→sg, sl+l- decays proceed via FCNC
Box and penguin diagrams
b→sg
• Br(b→sg) ≈ 3.5×10-4
• Br(b→sl+l-) ≈ aem×Br(b→sg) ≈ 106
• New particle (via loops) may make
appreciable contribution to decay
rates and/or asymmetries.
• Good testing ground of
SM and beyond SM.
b→sl+l-
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
X(3872) Produktion in B Zerfällen
Recently, Belle observed the X(3872) in B+->X(3872) K+ decay,
with X(3872)->J/Y p+p- (confirmed by CDF, D0 and BaBar).
Br(B-K-X3872) Br(X3872pp-J/)
Br(B-K-’) Br(’pp-J/) = 0.063 ± 0.012 ± 0.007
Y’
35±7 events
M=3872.0±0.8 MeV
G<2.3MeV (90%)
M(J/Y p+p-)
X(3872)
M(J/Y p+p-) – M(J/Y)
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
Charmonium Spektroskopie
cc1’
hc’’
hc’
hc2 Y2 Y3
< 1 MeV/c2
X(3872)
MD*+MD
c
Y’
cc0 c1
hc
J/Y
hc
2MD
cc2
Decay to J/Y p+pIsospin 0++
allowed
Isospin 1-violating
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
Studie der X(3872) Produktion in B Zerfällen
 Search for B gX(3872)K decay,
with X(3872)gcc2g. 152x106 BB pairs
DE
MB
G (Xgcc2g)
= 0.42 ± 0.45 ± 0.23 <1.1 (90%CL)
G(XgJ/Ypp-)
 Search for B gX(3872)K decay,
with X(3872)gJ/Y g.
G (XgJ/Y g)
G(XgJ/Ypp-)
MB
DE
MX
=
0.22 ± 0.12 ± 0.06 <0.40 (90%CL)
|cos q|
 Helicity angle: if Jp=1+- (hc’),
sin2q angular distribution is
expected.
g ruled out by data.
X
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
Studie vom B+  X(3872) K+ Zerfall, X(3872) J/Y p+p-p0
274x106 BB pairs
Events within B signal region and
mass interval:
| M(J/Y p+p-p0) – 3872. | < 12 MeV/c2
Assuming events with M(3p) > 0.75 as J/Yw :
G (XgJ/Yw)
G(XgJ/Ypp-)= 0.8 ± 0.3 (stat) ± 0.1(syst)
It provides support for DD* molecular
interpretation of X(3872).
events with M(3p)>0.75 GeV
These events are
almost pure signal
Nevt=10.0 ± 3.6
S/N = 5/1
Signif = 5.8s
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
Welcher Zustand ist X(3872)?
_
Keine guten cc Kandidaten für X(3872):
hc”
M too low and G too small
hc’
angular dist’n rules out 1-
cc1’
G(gJ/) way too small
2
G(gcc1) too small; (PRL 93, 2003)
hc2
3
pp hc should dominate ppJ/
G( gcc2 & DD) too small
- Isospin violating decays to J/Y p+pNeue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
Neue Charmonium Resonanz ?
Interpretation:
• Masse gerade an der D0D*0 Schwelle
• lose gebundenes “molecular charmonium”, oder ein Y(13D2) Zustand?
Ersteres in der Literatur diskutiert seit 1975:
– ausgelöst durch komplizierte Struktur von s(e+e- ->hadrons) bei SPEAR
•
•
•
M. Bander, G.L. Shaw, P. Thomas, PRL 36, 695 (1976)
M.B. Voloshin, L.B. Okun JETP Lett. 23, (1976), Pisma Zh.Eksp.Teor.Fiz.23, 369 (1976)
A.De Rujula, H.Georgi, S.L.Glashow, PRL 38 (1977)
– WW beschrieben durch p-Austausch gibt attraktive Kraft für DD*, BB*
D0D*0
Molekül
•
N.A. Tornqvist, PRL 67, 556 (1991), Z.Phys. C61, 525(1994)
•
A.V. Manohar, M.B. Wise,Nucl.Phys. B339, 17(1993)
q
Ältere Ideen:
q
Q
Q
Lose Bindung
Decays to (QQ)+(light mesons) via quark
rearrangement which suppresses the width.
q
q
Q
Q
Stärkere Bindung
Diquark Model
(Qq) are colored
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
Zusammenfassung (1)
SM bisher überraschend selbst in Details erfüllt!
Bestimmung der CKM-Matrix-Elemente im SM
Indirekte CP-Verletzung A(t) bestimmt mit hoher Präzision
sin21(bgccs) = 0.726  0.037
Grosse Anstrengung auch die beiden anderen Winkel zu messen
(2 und 3)
Außerdem „Seitenlängen“ des Dreiecks: Dmd und Dms, sowie
Vub/Vcb etc.
Bedeutet anderer Wert sin21(bgsqq) = 0.41  0.07
(3.8 s) schon „neue Physik“ oder
„nur“ Penguin-Beitrag ?
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004
Zusammenfassung (2)
Beträchtliche Direkte CP-Verletzung (3.9 s )
ACP (B0  K+p -) = -0.101  0.025  0.005
Asymmetrie Materie-Antimaterie im Universum ?
Molekül D*0D0 = 4 Quarkzustand
oder konventionelle Erklärung?
Neues Gebiet: Ds- Spektroskopie
etc.
BELLE ist bei vielen Gebieten an vorderster Front:
 SUPERBELLE mit höherer Luminosität
Neue Resultate vom BELLE Experiment
Mainz G.Leder 17.November 2004