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Recent results from the E852 data analysis. Motivation, E852 vs GlueX PWA basics p 0 p 0 production hp and h ’ p spectra : have we seen exotics yet ? Computational challenge Outlook. Why mesons ?. ‘Simplest’ QCD states Lab for fundamental symmetry tests

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Recent results from the E852 data analysis

  • Motivation, E852 vs GlueX

  • PWA basics

  • p0p0 production

  • hp and h’p spectra : have we seen exotics yet ?

  • Computational challenge

  • Outlook


Why mesons ?

‘Simplest’ QCD states

Lab for fundamental symmetry tests

Heavy QQ are non-relativistic

Light meson are chiral eigenstates

Beyond the quark model : glueballs, exotics

Bridge between QCD and the S-matrix theory

DcSB

quark model

JPC = 0--,0+-,1-+,2+-, L


Meson spectroscopy : open issues

over O(100) light mesons listed in the PDG

~ O(10) in the summary tables

~ O(1) properly described


a

M2x = (pa + pb)2

p-, g

b

S = (pg + pp)2

p

t=(p’N – pp)2

N’

s » 40 GeV2 , Ep, LAB =18 GeV

s . 20 GeV2 , Eg, LAB =8-9 GeV

t < 1 GeV2

t < 1 GeV2

Mx. 3 GeV

Mx. 2.5 GeV

Kinematics of peripheral production

t/s << 1

GlueX

E852


… the less you know the more ambiguous the answer …

0 physics input

“maximal’ ambiguity

some physics input

“moderate” ambiguities

know everything

no ambiguities

You do it in all possible way

to study systematics


a

c

a

c

t=sac

s=sab

a

b

d

b

d

Dynamics of peripheral production I

s/t !1

T(s,t)

x(t)b(t) sa(t)

L = Rea(t)

Resonance (or bound state Ima=0)


Quasi-two body reactions

p-(18GeV) p  a2 p  h p0 n

t

E852

p-

a2

s

dN/dt

p

n

Natural exchange (r)

Unnatural exchange (b1)


t1

p0

p-

M

p0

s

s1

p-

p0

p

a1

t

_

p0

n

a

II Multiple particle production

p- p !p0p0 n

Regge + particle 4 point function

s/t,s/t1,s/M2!1

t,a

M2 ~ s

M2<<s

~FESR~


p- p !p0p0 n

(J. Gunter et al.) 2001

f2(1270)

s(400-1200)

p0p0 spectrum



O(p2p/f2p)

p

p

=

Low order c expansion

p

p

+

Higher order c expansion

+ unitarization

Interplay between “elementary” (CDD) and “dynamical” resonances


pp (S=I=0)

pp

2 Resonaces @ ~1.3, 1.5 GeV

pp+KK

pp only

(no KK, no resonances)


“Global features” of the hp0, hp-, h’p- production

hp0

Mass dependence

t-dependence

Relevant partial waves :

S D0 D- Po P- (unnatural)

D+ P+ (natural)


p- p !hp0 n

(M.Swat, Ph.D thesis) 2003

(A.Dzierba et al.) 2003

a0 and a2 resonances


hp0 vs hp-

C is a good quantum number

ao and a2 are produced (helps with ambiguities)


Work in progress on full hp- sample O(100K) events !

very low t<0.1 GeV2

a0(980)

not seen before

r exchange


P-wave results from the hp0 data

p1(900 – 5GeV) emerges

No consistent B-W description of the

P-wave fund when all helicity amplitudes

where taken into account

Intensity in the weak P-waves is strongly

affected by the a2(1320), strong wave

due to acceptance corrections


1 BW resonance in P+

2 BW resonances

in D+

a2(1800) = ?

a2(1320)

E852 h’p- analysis


What is the origin of the P-wave in the hp, h’p

… combine Regge description with chiral constraints

M

s>>t,M

Chiral

Regge

t

vs quasi-two body

(resonance)

rescattering (dual) to diffraction


p- p !hp- p

Results of coupled channel analysis of

p- p !h’p- p

D

D

P

S

P

P-wave comes entirely from background : no resonances needed


1-+ exotic : current status

hp- : p1(1400) G > 350 MeV

h’p- : p1(1600) G > 350 MeV

hp0 : p1(1400) G > 350 MeV

Can be explained in terms of

hp - h’p rescattering

Constrained by the standard

SU(3)L£ SUR(3) £ UA(1)

effective lagrangian

Currently is being reanalyzed

Using 150M (full) event sample

(compared to 250K)

rp : p1(1600), G < 200 MeV


An exotic signal in 3 p
An Exotic Signal in 3p

Correlation of

Phase

&

Intensity

Leakage

From

Non-exotic Wave

due to imperfectly

understood acceptance

Exotic

Signal


p- p !p-p+p- p

E852 2003

Full sample

CERN ca. 1970

BNL (E852) ca 1985

Software/Hardware from

past century is obsolete


gp vs pp data

Compare statistics and shapes

Adams ’93 (E852) p- p -> p+ p-p+ p @ 18 GeV

Condo’93 g p -> p+ p-p+ n @ 19.3 GeV

a2

SLAC

28

p1 ?

Events/50 MeV/c2

p2

a1

SLAC

BNL

4

1.0

1.5

2.0

2.5


1-+ exotic : S=1, L=1

g --> r(JPC=1--) --> p1(JPC=1-+)

VMD

“pluck” the string (S=1,LQQ=0->Lg=1)

Photo production enhances exotic mesons

Condo’93

OPE


p- p -> X0 n

g p -> X+ n

18GeV

a2

10%

p1

5 GeV

a2

In photoproduction

p1

~ 50% - 100%

a2

p1

8 GeV

M.Swat, AS


Computational challenge
Computational challenge

p- p !p-p+p- p

Step 1 - Reconstruction and Monte Carlo

50M

25M

M.C. data (150M)

Reconstruction

and

Kinematic

Fitting

More

Filters

16M

9M

Data (78M)

This involves several hours of M.C.generation and staging of about 1TB ofdata to disk and processing Time required: about a weekPerhaps re-done 2 or 3 times

Multiplepasses tounderstandcuts


p- p !p-p+p- p

Step 2 - Preparing Data and Fits

p-

Current model

resonance region

p-

a2,a1,p2L

p+

with the existing software

design this can take up to 1 week !

on 100 processors(40 x 80 x 10 = 32000 files)

r,f2,f0,L

p-

a

n

p

This is the inputto the fitter.

Each time a changeis made to the modelthe inputs must beregenerated

For each eventcompute massesand angles andall invariants and

waves thatdepend on massesand angles

Typical # ofamplitudes: 40 or so

150M

240 GB

This is being redesignedin current version this step takes

< 1h !

25M

40 GB

15 GB

9M


MANTRID

Modern amplitude analysis

AVIDD cluster

(Analysis and Visualization of Instrument-Driven Data)

2x208 2.4 GHz Pentium

(IUB + IUPUI)

Original E852rp exotic based on0.5M events

Now processing 10M

36-processor cluster with 1.6Tb of storage


Preliminary results from full E852 sample

p2(1670)

a2(1320)

Chew’s zero ?

Interference between

elementary particle (p2)

Or the CDD pole with the

unitarity cut


Inelastic diffraction : is p(1800) a hybrid ?

ds/dt = Ae10t


Why Hall D can resolve issues in meson spectrum

  • Several orders of magnitude increase in statistics

  • “Unlimited” computational resources

  • New developments in theory, LGT, c EFT

  • High energy, intensity, polarized photon beams


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