New Particles at BELLE Beauty 2005 Assisi Spectroscopy and new Particles F. Mandl There is an impressive list of new particles in the charm sector discovered

New Particles at BELLE

Beauty 2005 Assisi Spectroscopy and new Particles F. Mandl

There is an impressive list of new particles in the charm sector discovered by BELLE in the last few years:

This talk covers only Not included in this talk

X(3872) c(3753) Phys. Rev. Lett. 89 (2002)

X(3940) (2308)

Y(3940) Phys. Rev. Lett. 94 (2005) D1(2427) c(2800) Phys. Rev. Lett. 94 (2005)

Phys. Rev. D 69 (2004)

D0*




Discovery of X(3872) J/

History

Discovery by BELLE :

narrow J mass peak

in excl. B K J decays Phys. Rev. Lett. 91, 262001 (2003)

has been confirmed by CDF II, D0, BaBar

m, not compatible with charmonium state

m peaks near upper kinematic limit as expected for

but : charmonium decaying to J/ violates isospin suppressed


X(3872) observation


Theoretical Explanation for X(3872)

What could it be?

Mx = (3871.9 ± 0.5) MeV is within error equal to the threshold (3871.3 ± 1) MeV

Speculation: X might be a molecule - like bound state

Tornquist: JPC = 0-+, 1++ C = +1

J via 0J/ intermediate state m concentrated at high masses

Swanson: dynamical model for X as a hadronic resonance

JPC = 1++ strongly favoured

+ appreciable admixture of J/ + small J/

Decay X(3872) J/ observation would unambiguously establish C = 1 for X

D0D *0

D0D *0

D0D *0

D0D *0


Study of X(3872) J/

Study B K J/

256 fb-1 data sample (275 M )

Selection: J/, K0 or K, Ptab > 40 MeV

to reduce continuum events (e+e- qb)

R2 < 0.4 (normalized Fox-Wolfram moment)

|cosB| < 0.8 B polar angle of B in cms

B KJ/ are identified by

E EBcms Ebeam

cms

Mcb (Ebeamcms )2 (PB

cms )2

BB

qq


Evidence for X(3872) J/

Constraint: Signal Region:

Mbc > 5.20 GeV 5.2745 < Mbc < 5.2855 GeV

|E| < 0.2 GeV |E| < 0.035 GeV

Prominent peak near 3510 MeV in M(J/) is used for calibration

The only significant B-meson signal is in the 3872 MeV bin (also for E-distribution)

Simultaneous fit of Mbc and E and background (ARGUS function for Mbc and first order

polynominal for E):

Signal yield: 13.6 ± 4.4 events,

Significance: 4.0

(from B Kc1, c1 J /)



4


Evidence for X(3872) J/

X J/ similar selection as above

slightly different signal region

only significant B-meson signal in 3872 MeV bin (not shown)

Mbc distribution for various inv. mass bins:

only significant B meson signal for M() > 750 MeV bin

the same for E

Fit: 12.4 ± 4.1 events Significance: 4.3

possible background B K J/ fit: 0.75 ± 0.14 events

B K J/ non res., use left and right side bound region

1.3 ± 1.0 events

0 , fit : 2 6, p0

cms 180MeV

|M ( J /) m((2S)) | 3

Br(X 0J /)

Br(X J /)1.0 0.4 0.3




X(3

872)

+

J/

A ~ J/xprelp waves

Lint

1-p = 4%, 0.01%

Transversity analysis useful for decays to V + V

triple scalar product

rest frame

J/

in rest frame


X(3

872)

+

J/

A ~ J/Lint

1-p = 0.3%, 5x10-6 %

common rest frame

of J/ and0

(relativ momentum maybe neglected)


X(3

872)

+

J/

A ~ xJ/

pJ /* p

* 0

Lint

1-p = 75%, 16%

triple scalar product

in X rest frame

(D = 0)

neglecting rel.mom.

between J/ and 0 :

all are in same CMS


X(3

872)

+

J/

centrifugal

barrier !


3 pseudoscalars require D-wave


I-violating

hadr.trans.:

(2S) J/


X(3940)

Further analysis of the processes

History: first observation of such processes by BELLE

Phys. Rev. Lett. 89, 142001 (2002)

Theoretical calculation:

various speculations: glueball contribution ? etc.

For the first time seen:

X(3940) new charmonium state

Look for recoil to J/and (2S) etc.

ee J / c (1S) (Xc0,c (2S),X )

ee (2S)(cc ) res

ee J /c ~ 2fb measurement

Mrecoil (J /) (Ecm EJ /* )2 pJ /

*

double charmonium


Study of the decay of reconstructed (2S) J/

search for

look for recoil spectra

3 significant signals seen:

(BaBar gets consistent results)

ee (2S)(cc )res

e+e- J/X


Using higher statistics (287 fb)

extend analysis of recoil masses against J/ above DD threshold

find new significant peak at M ~ 3.940 GeV/c2 “X(3940)”

Fit: c, co, c(2S), X(3940) + background

MX = (3.937 ± 0.012) GeV/c2

compatible with 0 (< 95 MeV/c2) 90% CL <~ resolution (=32 MeV)

no signal of X(3872)



≠ X(3940)


Charmed baryon spectroscopy

light diquark in the environment of a heavy quark test for theoretical models

PDG 2004: 4 excited charmed baryons observed

c(2455) ground state c(2520)

Aim : find excitations of c

Analysis: uses data sample 253 fb-1 at (4S),

signal window around : ± 8 MeV/c2

xp > 0.5 for candidates

yield: (516 ± 2) x 1013 S/B = 2.3

combine with xp > 0.7 cosdec > -0.4

dec = angle between ( in rest frame of ) and boost direction of the

system in cms

c

c

c

are reconstructed via pK

m(c )

c

xp p *

pmax*

c

pmax* Ebeam

*2 M 2

c

c


(0) (+) (++)


Charmed baryon spectroscopy

c(2800)0 c(2800)+ c(2800)++ Isotriplet

Enhancement at M ~ 0.43 GeV for M( ) and M( +)

feed-down from decay c(2880)+ + observed by CLEO

next: study +: clear peaks of c(2800)+ and c(2765)+ seen

consistent with observation of CLEO

Fit: Isotriplet + feed-down + combinatorial background

(e+e- c(2800)X) x Br(c(2800) ) 2.04 (0), 2.6 (+), 2.36 (++) pb

Theoretical models

c2 doublet with Jp = 3/2- and 5/2- c2 mainly in D wave

M = 500 MeV/c2 as measured ~ 15 MeV smaller as measured

c2(JP = 3/2-) can mix with c1(JP = 3/2-) and would produce a wider physical state

c

c

c

c

c

c


Summary

c(2800) triplet established

X(3940) new charmonium state

tentative identification: c2, JP = 3/2-; c1, JP = 3/2- admixture

ee (2S)(cc ) res seen for the first time (now also BaBar)


SPARES

Continuum Suppression

e+

e-

e+

e-

qq

Signal B

Other B

Unwanted Background for B-Decays:

Continuum

Jet-like

BB

spheric

e+e qq “continuum” (~3x BB)

To suppress: use event shape variables

continuum

Y (4S)


Continuum Suppression

To separate spherical BB events from jet-like continuum events, topological variables are used:

1) Second Fox-Wolfram moment2) Super Fox-Wolfram (six modified Fox-Wolfram

moments, Fisher discriminant)3) Angle between B meson and beam axis direction4) Angle between thrusts of selected B meson particles and

all other particles in event

Likelihood ratio includes all info.








JPC possibilities for X(3872)

• J ≤ 2• DD allowed & P-violating unlikely

• signal for X γJ/ψ

C=-1 ruled out• check of angular distributions

rules out 1±-,0±+,2-- • fits of Mππ

2-+ unlikely • X(3872) = χc1‘?

unlikely, since mass and BR ratio way off theo. expect.

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New Particles at BELLE Beauty 2005 Assisi Spectroscopy and new Particles F. Mandl There is an impressive list of new particles in the charm sector discovered