B. Golob, BelleTopics in charm hadron studies at Belle 1Particle Physics Seminar, UCL B. Golob University of Ljubljana Belle Collaboration Outline 1.Introduction.

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


http://kekb.jp/

Introduction conted


√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


J=3/2 J=1/2L=0

New spectroscopy non-exotic states


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


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.)

..%[email protected]

)(

)()(

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


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


Forrest Gump (1994)



Right sign charge comb.: c+ KS -


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


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 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



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



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)



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++



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


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


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


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


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


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'


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


PRL96, 151801 (2006), 400 fb-1


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


PRL96, 151801 (2006), 400 fb-1


(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.


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


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:


1

Summary


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)

B. Golob, BelleTopics in charm hadron studies at Belle 1Particle Physics Seminar, UCL B. Golob University of Ljubljana Belle Collaboration Outline 1.Introduction.

Documents

charm studies c c

ucl b c c s u

belle s s c

ucl c c d u d u u d

u c d d c u u

belle b

x c y c pairs

belle slide