Hadron physics experiments at J PARC · 2014. 8. 22. · • Experiment at J‐PARC II – Meson properties in nucleus 2014/8/22 K. Ozawa, CNS Summer School 2. Hadronand Hadron Physics

Hadron physics experiments at J‐PARC

K. Ozawa (KEK)

2014/8/22 K. Ozawa, CNS Summer School 1

Contents• Introduction

– What is hadron physics?– What is J‐PARC?

• Experiment at J‐PARC I – Charmed Baryon Spectroscopy

• Experiment at J‐PARC II– Meson properties in nucleus


Hadron and Hadron Physics• Hadron is a particle which have a “strong interaction”– Baryons, such as protons, neutrons– Mesons, such as mesons, mesons, … – Naively speaking, particles which consist of “quark”s

• So many hadrons are observed by now

• Hadron physics is a natural extension of nuclear physics to study following topics– Internal structure of baryons and mesons– Origin of interactions between hadrons– Nucleus as a nuclear matter


Quarks


Proton

Currently, observed quarks

u

u d

up charm top

down strange beauty

• There are three generations. The second and third generations have the same role, but heavier masses.

• Using heavier quarks, nucleus and hadron interactions can be studied using a different way.

Charge +2/3

Charge ‐1/3

1Generation 2 3

Light Heavy

Our world consists of up and down quarks

Example: Strangeness Nuclear Physics

• Let’s think about baryons which contain a strange quark.

• Such baryons can avoid a “Pauli‐blocking” and we can put it deep inside a nucleus.

• Such baryons have a similar energy state with a nucleon and we can study nucleon state levels in nucleus directly.

• At KEK‐PS, an experiment is performed to study baryon states in nucleus.


PRC 64 (2001) 044302

‐> U = ‐ 28 MeV(c.f. UN ~ ‐50 MeV)

Strange baryon () states measured at KEK_PS

Energy States are clearly seen.Binding Energy is different

It is important as a basic information for a neutron star

Requirements for experiments• To perform such experiments, we need

– Relatively high energy beam • Pair production of strange quarks ~ 1000 MeV• Charm quark ~ 3000 MeV

– High intensity • To cope with small cross section

– Several beam species• meson, Strange meson (K meson), Anti‐proton, muon

• To achieve such requirements, we construct an accelerator complex– Japan Proton Accelerator Research Complex (J‐PARC) provides a high intensity proton beam and generate several secondary beams


J-PARC (Japan Proton Accelerator Research Complex)

J-PARC (Japan Proton Accelerator Research Complex)

Tokai, JapanTokai, Japan

50 (30) GeV Synchrotron (15 A)

400 MeV Linac (350m)

3 GeV Synchrotron (333 A)

Material and Biological Science Facility

World-highest beam intensity : ~ 1MW x10 of BNL-AGS, x100 of KEK-PS

Neutrino Facility

Hadron Hall60m x 56m

2014/8/22 7K. Ozawa, CNS Summer School

30 GeV Accelerator & Hadron Experimental Facility


Branch Point from Acc. to Hadron

Transfer Line from Acc. to Hadron

Hadron Experimental Facility

Current Production target for secondary beams

New Beamline (under construction)

K. Ozawa, CNS Summer School 9

Hadron Experimental Facility

K1.8BR

KL

K1.8

K1.1High-p

COMET

Name Species Energy IntensityK1.8 ±, K±

KL

North side

South side

SKS

K1.8BR


New Beam Line is under construction

Construction of New Beam Line is on‐going. Multi Purpose beam line for following beams

Primary Proton Beam (30GeV), 1010‐12 per spillHigh Momentum un‐separated secondary beam (20GeV/c), 108 per spillPrimary Proton Beam (8GeV) for COMET

PhysicsHadrons in nucleusHadron spectroscopy mu‐e conversion (COMET)

2014/8/22 11K. Ozawa, CNS Summer School

In this lecture, I will introduce new experiments using a new beam line.

Experiments @ new beam line

• Internal Structure of Hadron– Charmed baryon spectroscopy can provide essential information, especially for Di‐quark correlations

• Hadrons in nucleus– Hadron mass is dynamically generated and strongly related with nuclear medium properties.

– Experimental information of hadron mass in nucleus


INTERNAL STRUCTURE OF HADRON (PROTON, PION, … )


Structure of proton and meson• Several experimental data

support existence of quarks in proton and meson– Electron‐proton scatterings

show internal structures• R.W. McAllister and R.

Hofstadter, Phys rev. 102(1956), 851

• M. Breidenbach et al., Phys. Rev. Let. 23(1969), 935

• “Quark model” including strange quark explains existing baryons and mesons very well – Proton and baryons contain

three quarks– Mesons contain quark – anti‐

quark


Spin 0

Baryon

Spin 1/2

Meson

Spin 3/23 3 3

3 3

Properties of interaction btw quarks• Measurements of excitation states are always a good method to study a structure.

• Especially, meson is a two‐body system and excitation states can be measured as excited resonances.– Measurements of charmonium (charm – anti‐charm mesons)


Observed charmonium states

A potential btw anti‐quark and quark is evaluated as a/r+b*r (a,b const.).

Baryons• Quark‐quark interactions and inside structure of baryons are also studied using excited states.


Summary table in S. Capstick, N. Isgur, PRD34 (1986) 2809• However, it is difficult to

extract detailed properties of quark interactions – A Baryon contain three

quarks and it should have many body effects

– Large width due to strong coupling to meson

• Naïve quark model can’t explain the current experimental data– Additional effects should

be consideredColored: Observed stateBars: Model Prediction

Di‐quark correlation• One of possible strong effects is a quark‐quark (Di‐quark)

correlationColor‐Magnetic Interaction of two quarks

VCMI～[s/(mimj)]*(ij)(ij)

“Good Diquark”: Strong Attraction

VCMI(1S0, ͞3c) = 1/2*VCMI(1S0, 1c)[qq] [͞qq]

• Diquarks are emerged due to the color magnetic interaction between two quarks.

• The so‐called “good diquark” has a color anti‐symmetric 3bar and spin singlet configuration. It’s strong enough.

• One expects that a “qood diquark” may be formed in a baryon.


Emergent DiquarksBaryons as well as Mesons seem to be well described by a

Rotating String Configuration with a universal string tension.

M2~LA distance of [qq]‐q/ ͞q‐q increases as L increases.

q

͞q


qq

q

L L

Emergent Diquarks

0

1

2

3

4

5

6

7

8

9

10

0 1 2 3 4 5 6 7

NDeltaLambdaSigmaXi

0

1

2

3

4

5

6

7

8

9

10

0 1 2 3 4 5 6 7

rho/aomega/fphi/fK*

Baryons Mesons

LL

M2(GeV

2 ) M2∝1.1L M2∝1.1L

Baryons as well as Mesons seem to be well described by a Rotating String Configuration with a universal string tension.

2014/8/22 19

Emergent DiquarksBaryons as well as Mesons seem to be well described by a

Rotating String Configuration with a universal string tension.

“diquark”in low‐lying modes


qq

qA diquark-quark picture of baryons seems valid in low-lying modesHowever, it is difficult to study strength of a di-quark correlation only using light quarks, because all combination of qq contribute and interfere.

Charmed Baryon

Q

qq

Weak Color Magnetic Interactionwith a heavy Quark

• [qq] is well Isolated and developed

• Level structure of Yc* provides diquark properties• “diquark mass”

VCMI～[s/(mimj)]*(ij)(ij)


Level Structure and motion• When single quark picture is

still a good picture, excited states are degenerated.

• If Cqq (q=u,d) system is considered as C and di‐quark correlations, orbital motion of is lowered due to the collectivity of the di‐quark motion.

• Spin correlations between light quarks give additional level separations.

2014/8/22 22

: orbital motion: di‐quark correlation

K. Ozawa, CNS Summer School

Measurements of all levels are important

Level pattern tell us:Mass of di‐quark Strength of di‐quark correlationSpin dependent correlation between light quarks

c 1/2+

c(2455) 1/2+c(2520) 3/2+

c(2800) ??

c(2595) 1/2‐

c(2625) 3/2‐

c(2880) 5/2+

c(2940) ??

DN

c

(GeV/c2)

D*N

2.3

2.4

2.7

2.9

2.6c

Limited # of Charmed Baryons have yet been observed.

mode

mode


New Experiment:Charmed Baryon Spectroscopy

Using Missing Mass Techniques

D0(Yc’)

p

Inclusive p(‐,D*‐) Yc*+

p(‐,D*‐p)D0

Yc*+( p(‐,D*‐)Yc’ ) (Target)

Charmed baryons are observed in the missing mass spectrum using p(‐,D*‐) Yc*+ reaction.In addition, the decay mode can be identified


What we will measure

• Production Rate: reflect quark configurationHeavy quark + light diquark

• Spectrum identified by productions Basic modes of diquark motions (λ/ρmodes) Spin (Heavy Quark) multiplets

• Decay propertiesM(Qqbar) + N(qqq) / m(qqbar) + Yc(Qqq)


Production

p Yc*

L

D*

D*, D

One‐step, t‐channel dominant

λmodes are excited by a simple mechanism• HQ spin doublet• Spin/Parity from Production Ratio

Note: Production Cross Section does not go down at higher L due to large effective momentum transfer

arXiv: 1405.3445


2014/8/22 K. Ozawa, CNS Summer School 27SU(3) limit Heavy Quark (HQ)

• • •

• • •

MQ mq MQ mqSU(3) limit Heavy Quark (HQ)

L = 1

L = 2

L = 1

L = 2

isotope shift ‐dep. int.

5/2+3/2+

3/2‐1/2‐

L = 01/2+

A heavy quark differentiates diquarkmotions = modes and modes are distinct ~ isotope shift

HQ doublet

HQ doubletIn the heavy quark limit, the heavy quark spin decouples to the others.

HQ doublet HQ doublet

L = 1 L = 2L = 0

1/2‐ 3/2‐ 5/2+ 3/2+1/2+

1 : 2 3 : 2

c c(2595)

c(2800)

cc*

c(2625)

c(2880)

c(2940)


Decay Properties

qq

qqQ

qqq

Qq

mode (qq) mode [qq]c ) > pD) c ) < pD)


Dispersive Focal Point（DP)p/p~0.1%

Collimator (IF)

15kW Loss Target

Exp. TGT（FF)

SpectrometerT1

QQQQD

QQD D

D D DQ

QQSS S

DD QQD

DQQ

Magnet:D : DipoleQ : QuadrupoleS : Sextupole

High‐res., High‐mom. Pion Beam• High‐intensity secondary Pion beam can be delivered.

– 2 msr・%、1.0 x 107 Hz @ 15GeV/c • High‐resolution beam: p/p~0.1%

– Momentum dispersion and eliminate 2nd order aberrations


Charmed Baryon Spectrometer

Large acceptance ~ 60% (for D*), ~85% (for decay +) Good resolution: p/p~0.2% at ~5 GeV/c

LH2‐target

Ring ImageCherenkovCounter

Internal DC

FM magnet s

Fiber tracker

Beam GC

Internal TOF

Internal TOFDC

TOF wall

2m

Decay p()

20 GeV/cBeam


32

Summary for charmed baryon• Charmed Baryon Spectroscopy via the (,D*‐) reactions– Shed light on “diquark”: colored object in hadrons– Clarify a Level Structure of the charmed baryons

• From the ground state to highly excited states of Ex~1 GeV• Independent of decay final states

– Decay Branching Ratios (Partial Widths)• Suppressions of [qqbar]‐[qqQ] decays if “Good diquark” in Yc*• Possible assignment of spins

• A New Project of Hadron Physics at J‐PARCHigh‐res., High‐intensity 2ndary Beam– Large Acceptance, Multi‐Particle Spectrometer

2014/8/22 K. Ozawa, CNS Summer School

Documents

Hadron physics experiments at J PARC · 2014. 8. 22. · • Experiment at J‐PARC II – Meson properties in nucleus 2014/8/22 K. Ozawa, CNS Summer School 2. Hadronand Hadron Physics