b. golob, belletopics in charm hadron studies at belle 1particle physics seminar, ucl b. golob...
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B. Golob, Belle Topics in charm hadron studies at Belle 1 Particle Physics Seminar, UCL
B. GolobUniversity of Ljubljana
Belle Collaboration
Outline1. Introduction B-factory = charm-factory
2. New spectroscopy Exotic/non-exotic?
3. D0-D0 mixing Last man standing
4. Outlook
Topics in charm hadron studies at Belle
3.5 GeV e +
8 GeV
e-
Belle
Continuous injection, peak luminosity: L = 16.5 nb-1 s-1
Integrated luminosity: Ldt 700 fb-1
~1 km in diameter
Mt. Tsukuba
KEKBBelle
Mar. 2003 Oct. 2006
Introduction
B. Golob, Belle Topics in charm hadron studies at Belle 2 Particle Physics Seminar, UCL
Introduction conted
B. Golob, Belle Topics in charm hadron studies at Belle 3 Particle Physics Seminar, UCL
√s = M((4S))c2
(4s)
B (bu, bd)
B (bu, bd)
(b b) 1.1 nb (~750·106 BB pairs)
B B at rest in CMS system;asymmetric collider → measurabledecay dist.;numerous measurements in field of CPV in B system
* c
cLast years renewed efforts
in charm studies
(c c) 1.3 nb (~850·106 XcYc pairs)
+ light qq production
distinct kinematics and topology w.r.t. B Bjets of hadrons
continuum production
BB pair production
Charm is... a way of getting the answer yes without having asked any clear question. A. Camus (1913 - 1960)
3(4) layerSi det.
Central Drift Chamber
AerogelCherenkov(n=1.015- 1.030)
1.5T SC solenoid
e-
8 GeV
e+
3.5 GeV
EM calorimeterCsI (16X0)
and KL
Counter(14/15 layersRPC+Fe)
tracking (pt)/pt= 0.2% √(pt2+2.5)
PID (K±) ~ 85% (±→K±) 10% for p < 3.5 GeV/c
Introduction conted
B. Golob, Belle Topics in charm hadron studies at Belle 4 Particle Physics Seminar, UCL
J=3/2 J=1/2L=0
New spectroscopy non-exotic states
B. Golob, Belle Topics in charm hadron studies at Belle 5 Particle Physics Seminar, UCL
baryons: q1q2q3
qi=u,d,s,c
I3 (u: +1/2; d: -1/2)
S (s: -1)
C (c: +1)
s
E
EM
need to use non-perturbative QCD
experimental results on baryons testing ground for QCD models
baryons with C>1 not yet observed, except ofsingle exp. claim
New spectroscopy non-exotic states, conted
B. Golob, Belle Topics in charm hadron studies at Belle 6 Particle Physics Seminar, UCL
c
c
d
u
d
u
u
d
c
+
K-s
cc+
c+ K-
p
+
Selex, PRL89, 112001 (2002)
Minv(c+ K- +)
%20)(
)()(
X
KBrX
c
ccccc
Belle measurement with higher stat. (and bkg.)
)(
)()(
4
5.2)*(
LC
X
KBrX
GeVpc
ccccc
c
PRL97, 162001 (2006) 460 fb-1
p*(c+)>2.5 GeV
(c from continuum)
fit with bkg.+possible signal
production mechanism?
M=3519±1 MeV/c2
New spectroscopy non-exotic states, conted
Topics in charm hadron studies at Belle 7 Particle Physics Seminar, UCL
...Life is like a box of chocolates, you never know...:
Right sign charge comb.: c+ K- + Wrong sign charge comb.: c
+ K+ -
possible reflections from c*+ → c+ + -
with misidentified as K would appear here
PRL97, 162001 (2006) 460 fb-1
most plausible interpretation:
B. Golob, Belle
s s
c+
u
c
d
d
c
u
u
+
K-
u
c+ K-
p
+
strong decay of excited (L>0) c+
c+ isospin dublet c
0 (ddc)?
405 ± 50 evtssigificance 5.7
326 ± 40 evtssigificance 9.2
Forrest Gump (1994)
New spectroscopy non-exotic states, conted
B. Golob, Belle Topics in charm hadron studies at Belle 8 Particle Physics Seminar, UCL
Right sign charge comb.: c+ KS -
67 ± 20 evtssigificance 4.4
p*(c+)>3.5 GeV
(higher bkg.)
State Mass [MeV/c2] Width [MeV/c2]
c(2980)+ 2978.5±2.1±2.0 43.5±7.5±7.0
c(3077)+ 3076.7±0.9±0.5 6.2±1.2±0.8
c(2980)0 3082.8±1.8±1.5 5.2±3.1±1.8
confirmed by BaBar
questions: M, of c(2980)+ (2-3 difference with BaBar)
JP assignments
BaBar, hep-ex/0607042
first observation of two isodublets of excited (L>0) c
+
systematics from differentbkg. and signal parameterization
Neutral state
PRL97, 162001 (2006) 460 fb-1
New spectroscopy exotic states
B. Golob, Belle Topics in charm hadron studies at Belle 9 Particle Physics Seminar, UCL
PRL91, 262001 (2003) 152M BB
should be “exotic ?”; nature not known (yet)
X(3872) most prominent
observed by Belle B± → K± +-J/
22 )()2( iCMbc pEM
Reconstruction of B decays e+
ECM/2
e-
ECM/2
(4s)
B
B
∑ pi, ∑ Ei
signalsignal
2CMi EEE
(2S)If you search deep enough you can find rare exotic treasures. Christina Aguilera (b. 1980)
New spectroscopy exotic states conted
B. Golob, Belle Topics in charm hadron studies at Belle 10 Particle Physics Seminar, UCL
b c
c
s
u, du, d
(2S)
BK
X(3872) prod. and decay similar to cc
c’
J/c
c0c1
c2’
’”
hc
cc spectrum
MD+MD*
Mass M=3871.9±0.5 MeV/c2 (average)
intriguing: M - M(D0) - M(D*0) = 0.6 ± 0.9 MeV/c2
PRL91, 262001 (2003) 152M BB
M(+-J/)
hep-ex/0505038 275M BB
New spectroscopy exotic states conted
B. Golob, Belle Topics in charm hadron studies at Belle 11 Particle Physics Seminar, UCL
hep-ex/0505037, 275M BB
Possible JPC
C parity B±,0 → K±,0 X (→ J/)
no. of B’s (Mbc, E) in bins of M(J/)
13.6 ± 4.4 evts.(4)
C(X(3872))=+1
05.014.0)/(
)/(
JXBr
JXBr
B±,0 → K±,0 X (→ (+-) J/)
L=0, 2/ndf=43/39
L=1, 2/ndf=71/39
P=+1 (L=0) favoured
E side band
New spectroscopy exotic states conted
B. Golob, Belle Topics in charm hadron studies at Belle 12 Particle Physics Seminar, UCL
hep-ex/0505038, 275M BB
Angular distributions
B±,0 → K±,0 X (→ +- J/)examples shown
-l+ l-
X(J/)+
|cos()|
2/ndf=31/9 JPC=0++
JPC=1++
|cos()|
-
+K B
X(J/)
2/ndf=5/9
all J=0, 1, 2 disfavouredexceptJ=1++, 2++
also 2-+?, detailed study of M():
X→ D0D00 ?1++ →DD*: L=02++ →DD*: L=2,suppressed by (q*)2L+1
cc JPC
CDF, PRL96, 102002 (2006)
New spectroscopy exotic states conted
B. Golob, Belle Topics in charm hadron studies at Belle 13 Particle Physics Seminar, UCL
B±,0 → K±,0 X (→ D0 D0 0)
D0 D*0 and D0 D00
indistinguishable
PRL97, 162021 (2006) 455M BB
several D0 decay modes2-d (Q, E) unbinned lnL fit
Nsig=23.4±5.6
6.4 M=(3875.2±0.7±0.3
1.6±0.8) MeV/c2
0 reconstr.
EQ
if X(3872):
1.36.3
000
8.8)/(
)(
JXBr
DDXBr
hard to accommodate by 2++ state
JPC=1++
New spectroscopy exotic states conted
B. Golob, Belle Topics in charm hadron studies at Belle 14 Particle Physics Seminar, UCL
Remaining states
05.014.0)/(
)/(
JXBr
JXBr
~O(102)lower than prediction
almost all properties in agreement with DD* molecule model but...
cc 2-+ not quiteexcluded
E.S.Swanson,PLB588,189(2004)
cc 1++ c1’
Molecule model
1.36.3
000
8.8)/(
)(
JXBr
DDXBr
..should be.. ~0.08
further theoretical wisdom: large mixing between c1’ and X(3872)
It is characteristic of wisdom not to do desperate things. H.D. Thoreau (1817 - 1862)
New spectroscopy conted
B. Golob, Belle Topics in charm hadron studies at Belle 15 Particle Physics Seminar, UCL
c(2800) c(2980) c(3077)c(2880)
hep-ex/0608043 PRL97, 162001
PRL97, 162001PRL94, 122002
DsJ(2715)
hep-ex/0608031
X(3872)
X(3940)
Y(3940)
Z(3930)
Y(4260)
hep-ex/0505037
hep-ex/0505038
PRL91, 262001
PRL97, 162021
hep-ex/0507019
PRL94, 182002
PRL96, 082003 hep-ex/0612006
Other charm related spectroscopic results
Phenomena
D0-D0 Mixing
c
u
u
c
d, s, b
d, s, b
W+ W-D0 D0
neutral meson can change into antiparticle;box Feynman diagram
History
),( 2
,,,
2**00j
bsdjiiujcjuiciwk mmVVVVDHD
F
if mi = mj due to CKM unitarity: no D0 D0 mixing
|Vcb*Vub|<< |Vcs*Vus|, |Vcd*Vud|
mainly d,s contrib.; md ~ ms
mixing small
K0’sBd
0’sBs
0’s
mixing exp.verified
CDF, hep-ex/0609040
D0 casethe only system with down q’s in loop
the only system with unobserved mixing up to date
c
u
u
c
d, s, b d, s, b
W+
W-
D0 D0
Vci*
Vcj
Vuj*
Vui
B. Golob, Belle Topics in charm hadron studies at Belle 16 Particle Physics Seminar, UCL
D0-D0 Mixing conted
1|||,|
;;;)(
2sinh
2cosh)(
;2
;;
000
)2
1(0
1212002,1
ytxt
DfADfAD
tt
tyix
Ap
qtyix
AetDf
ymm
xDqDpD
ffdec
ff
tmi
Phenomenology
two mass eigenstates, linear superpos. of weak eigenstates
B. Golob, Belle Topics in charm hadron studies at Belle 17 Particle Physics Seminar, UCL
SM predictions x,y 10-3 - 10-2
rare process, appropriate for NP search;caveat: SM contribution not well known
Don't keep mixing in these other things. It only confuses. K. Kinski (1926 - 1991)
Wrong charge combinations (WS):D*+ → D0 slow
+ D0 → D0 → K(*)+ e- flavour tag at prod.
no “DCS” decays NWS/NRS = RM (x2+y2)/2
Observable:M = M(Keslow) - M(Ke)good resol., bkg. rejection
Reconstruct :pmiss = pCMS – pKe – prest
M(Keslow) M(D*+), M2() 0
PRD72, 071101 (2005), 253 fb-1
M from pmiss
M from pmiss
with constraints
right sign (RS)
NRS = (229.45 ± 0.69) ·103
Semileptonic decays
tetyx
tDK 2
2220
4)(
FWHM55→7 MeV
B. Golob, Belle Topics in charm hadron studies at Belle 18 Particle Physics Seminar, UCL
Reduce bkg., increase sensitivity:
<t >(bkg., RS) < <t >(mix. signal)
6 bins in 1 < t < 10
PRD72, 071101 (2005), 253 fb-1
iWS
iRS
iRS
iWSiM N
NR
,
,
,
,,
RM = (0.20 ± 0.47 ± 0.14) ·10-3
RM < 1.2 · 10-3 95% C.L.
dominating systematics from limited bkg. statistics (embedded slow)
)(
)(
)(
)(0
0
0
0
Dp
DL
Dc
DMt
Semileptonic decays conted
B. Golob, Belle Topics in charm hadron studies at Belle 19 Particle Physics Seminar, UCL
PRL96, 151801 (2006), 400 fb-1
Hadronic decays K+-
D*+ → D0 slow+ D0 → D0 → K+ -
DCS decays interference
tDD et
yxtyRRtDK
2
220
4
''')(
Wrong charge combinations (WS):
Observables:M= M(K)
Q = M(K slow) - M(K) - M()
2D M-Q fit:
NWS = 4024 ± 88
3 Q interval
3 M interval
WS
WSrateCF
rateDCSR
xyyyxx
D
sincos'sincos'
B. Golob, Belle Topics in charm hadron studies at Belle 20 Particle Physics Seminar, UCL
PRL96, 151801 (2006), 400 fb-1
Hadronic decays K+- conted
M, Q, t depent signal fractions used in decay time fit (WS):
)(4
'''),,( 2
22
tRetyx
tyRRQMf resolt
DDtsig
(RS decay time)
largest bkg. random slow
same resol. f. as signal
(D0) = 409.9 ± 0.7 fs
x’2, y’, RD free parameters
toy MC: no bias
B. Golob, Belle Topics in charm hadron studies at Belle 21 Particle Physics Seminar, UCL
PRL96, 151801 (2006), 400 fb-1
Hadronic decays K+- conted
RD = (3.64 ± 0.17 ) ·10-3
x’2 = (0.18 ± 0.210.23) · 10-3
y’ = (0.6 ± 4.03.9) · 10-3
AD = (23 ± 47) ·10-3
AM = (670 ± 1200) ·10-3
Results:
no CPV
CPV
CPV allowed:separate D0 and D0 tags(x’2,y’,RD) → (x’±2, y’±,RD
±)
MM
MMM
DD
DDD RR
RRA
RR
RRA
95% C.L. (x’2, y’) contourfrequentist, FC ordering
(0,0) lies on 96.1% C.L. contour
x’2 < 0.72 ·10-3
-0.99% < y’ < 0.68%no signif. CPV
largest syst. due to p*(D*) selection
B. Golob, Belle Topics in charm hadron studies at Belle 22 Particle Physics Seminar, UCL
PRL96, 151801 (2006), 400 fb-1
Hadronic decays K+- conted
(x, y) plane: 0o ± 70o
x [10-2]
y [10-2]
21
1
2Cleo-c, hep-ex/0607078, 281pb-1
RM 0.4·10-3
@ 95% C.L.
B. Golob, Belle Topics in charm hadron studies at Belle 23 Particle Physics Seminar, UCL
For my part I know nothing with any certainty, but the sight of the stars makes me dream.
V. van Gogh (1853 - 1890)
Outlook
Mixing and CPV searches:no evidence so farsemil. decays: RM < 1.2 · 10-3 95% C.L.
decays to K+-: RM < 0.4 · 10-3 95% C.L.most stringent limits on mixing paramers to date
decays to K+ n: precise WS rate measent
PRD72, 071101 (2005), 253 fb-1
PRL96, 151801 (2006), 400 fb-1
PRL95, 231801 (2005), 280 fb-1
A. Petrov, hep-ph/0311371
B. Golob, Belle Topics in charm hadron studies at Belle 24 Particle Physics Seminar, UCL
y[10-2]
x[10-2]
2
Outlook
1
BaBar+Belle 2 ab-1, charm fact. 20 fb-1
allowed excluded ~95% C.L.
0o ± 25o
K+- meas.KS t-dependent
Dalitz & K+K-/+-
y[10-2] 2
1
x[10-2]
New measurements under way:
B. Golob, Belle Topics in charm hadron studies at Belle 25 Particle Physics Seminar, UCL
1
Summary
B. Golob, Belle Topics in charm hadron studies at Belle 26 Particle Physics Seminar, UCL
B factories are producing charm hadrons in abundance; in many aspects competitive and complementary to charm factories (Cleo-c, BES)
Increased interest in charm physics in recent years
Several new (expected - understood/unexpected - non-understood) states observed; can serve as testing ground for better understanding of QCD
Rare processes - mixing - are exploited to search for unknown phenomena (NP); need better theoretical understanding, but first need to be observed
Prediction is very difficult, especially of the future.
N. Bohr (1885 - 1962)