pion and kaon photoproduction - jefferson lab€¦ · pion and kaon photoproduction césar...

Pion and Kaon PhotoproductionCésar Fernández-RamírezTheory Center, Jefferson Lab

1Theory Jamboree

Info

• Academic and professional experience

• 2001, Licentiate, Universidad Complutense de Madrid (Spain)

• 2003, MSc, Universidad Complutense de Madrid

• 2002-2006, PhD, Structure of Matter Institute (Spanish Council for Scientific Research) and Universidad Complutense de Madrid

• 2007, Research Assistant, Universidad Complutense de Madrid

• 2007-2009, Postdoc, CTP & LNS, MIT (USA)

• 2009-2011, Postdoc, ECT* (Trento, Italy)

• 2011-2013, “Juan de la Cierva” Research Fellow, Universidad Complutense de Madrid

• 2013-today, Postdoc, JPAC, Theory Center, Jefferson Lab.

• Research interests

• Hadron Spectroscopy

• Regge physics

• Effective Theories of QCD

• Chiral Symmetry Breaking

2

Contents

• Neutral Pion Photoproduction in the Near-Threshold Region

• Two Kaon Photoproduction

3

Neutral Pion PhotoproductionIn collaboration withA.M. Bernstein (MIT ),D. Hornidge (Mt. Allison U),M.Hilt, L. Tiator (Mainz),A2/CB-TAPS Collaborations (Mainz)

4

What for?

• ChPT is the effective field theory of QCD in the low-energy regime

• Testing ChPT we test hadron dynamics in the low-energy regime

• Spontaneous chiral symmetry breaking• i.e. Chiral Symmetry predicts:

• Soft S wave in neutral pion photoproduction. Vanishes in the chiral limit so that its value at threshold is explicitly chiral symmetry breaking

• Unknowns which have to be set from outside the Theory: LECs• Lattice• Experiment

5

Questions Arise

• It is an effective theory, so...

What’s the energy range of application?

Are we including all the right degrees of freedom?

6

Neutral Pion Photoproduction

• A2 and CB-TAPS collaborations at MAMI

• In the near-threshold region

• High accuracy

• Polarized photons

• LH2 target

• First measurements of photon asymmetry depending on the energy

γp → π0p

σ = dσ/dΩ

Σ ≡σ⊥ − σ

/σ⊥ + σ

Fig. ripped off from Zehr et al. Eur. Phys. J. A 48 (2012) 98

7

How Data Look Like

0.12

0.14

0.16

0.18

0.2

0.22

0.24

0.26

0.28

0.3

0 0.5 1 1.5 2 2.5 3

d/d

(!b/

sr)

(rad)

E =163.44 MeV

-0.04

-0.02

0

0.02

0.04

0.06

0.08

0.1

0.12

0 0.5 1 1.5 2 2.5 3 (rad)

E =163.44 MeV

8

Multipoles

• Single Energy

• Model independent extraction of S and P waves energy bin by energy bin

• D waves fixed to Born terms

• Empirical

• Taylor expansion in the partial waves + S wave cusp (unitarity)

• Provides consistency test for single energy extraction

• Chiral symmetry is not incorporated in this approach

• HBChPT

• Bernard, Kaiser, Meiβner, Z. Phys. C 70 (1996) 483Bernard, Kaiser, Meiβner, Eur. Phys. J. A 11 (2001) 209F-R, Bernstein, Donnelly, Phys. Lett. B 679 (2009) 41 F-R, Bernstein, Phys. Lett. B 724 (2013) 253

• RBChPT

• Hilt, Scherer, Tiator, Phys. Rev. C 87 (2013) 045204Hilt, Lehnhart, Scherer, Tiator, Phys. Rev. C 88 (2013) 055207

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Multipoles

-1.4

-1

-0.6

-0.2

Re

E 0+

(10-3

/m+ )

-0.35

-0.25

-0.15

Re

E 1+/

q (1

0-3/m

2 + )

6.67.07.47.88.28.6

Re

M1+

/q (1

0-3/m

2 + )

-3.8

-3.4

-3.0

-2.6

-2.2

140 150 160 170 180 190

Re

M1-

/q (1

0-3/m

2 + )

E (MeV)

EmpiricHBChPTRBChPT

10

Multipoles

-1.4

-1

-0.6

-0.2

Re

E 0+

(10-3

/m+ )

-0.35

-0.25

-0.15

Re

E 1+/

q (1

0-3/m

2 + )

6.67.07.47.88.28.6

Re

M1+

/q (1

0-3/m

2 + )

-3.8

-3.4

-3.0

-2.6

-2.2

140 150 160 170 180 190

Re

M1-

/q (1

0-3/m

2 + )

E (MeV)

EmpiricHBChPTRBChPT

D-wave uncertainty

10

Multipoles

-1.4

-1

-0.6

-0.2

Re

E 0+

(10-3

/m+ )

-0.35

-0.25

-0.15

Re

E 1+/

q (1

0-3/m

2 + )

6.67.07.47.88.28.6

Re

M1+

/q (1

0-3/m

2 + )

-3.8

-3.4

-3.0

-2.6

-2.2

140 150 160 170 180 190

Re

M1-

/q (1

0-3/m

2 + )

E (MeV)

EmpiricHBChPTRBChPT

D-wave uncertainty

First model-independent extraction of the S and P waves

Hornidge et al., Phys. Rev. Lett. 111 (2013) 062004

10

Multipoles

-1.4

-1

-0.6

-0.2

Re

E 0+

(10-3

/m+ )

-0.35

-0.25

-0.15

Re

E 1+/

q (1

0-3/m

2 + )

6.67.07.47.88.28.6

Re

M1+

/q (1

0-3/m

2 + )

-3.8

-3.4

-3.0

-2.6

-2.2

140 150 160 170 180 190

Re

M1-

/q (1

0-3/m

2 + )

E (MeV)

EmpiricHBChPTRBChPT

D-wave uncertainty

First model-independent extraction of the S and P waves

Hornidge et al., Phys. Rev. Lett. 111 (2013) 062004

10

Electroproduction, JLab Hall A, E04-007

χ2/dof depending on max energy/amount of data

1

1.5

2

2.5

3

3.5

4

155 160 165 170 175 180 185 190 195Emax (MeV)

2/dof

EmpiricalHBChPT

U-HBChPTBChPT

100127

154181

208237

266297

328359

390421

452483

514

Amount of experimental data11

χ2/dof depending on max energy/amount of data

1

1.5

2

2.5

3

3.5

4

155 160 165 170 175 180 185 190 195Emax (MeV)

2/dof

EmpiricalHBChPT

U-HBChPTBChPT

100127

154181

208237

266297

328359

390421

452483

514

Amount of experimental data

Δ?

11

More on Δ• πN has a big improvement if Δ is incorporated in relativistic ChPT

• Large Nc limit

• Δ is necessary to get a consistent scheme

• Fine interconnection between Δ and nucleons in loops

• Impact in peripheral charge density and magnetization

• Needed to get consistent connection with LQCD computations of gA

• Vector mesons in neutral pion photoproduction?

Alarcón, Martín Camalich, Oller, Ann. Phys. 336 (2013) 413

Edwards et al. (LHPC Collaboration), Phys. Rev. Lett. 96 (2006) 052001Bratt et al. (LHPC Collaboration), Phys. Rev. D 82 (2010) 094502

Granados, Weiss, arXiv:1308.1634 [hep-ph]Calle Cordón, Goity, Phys. Rev. D 87 (2013) 016019

Flores-Mendieta, Hofmann, Jenkins, Manohar, Phys. Rev. D 62 (2000) 034001Jenkins, Phys. Rev. D 53 (1996) 2625

Working on vector mesons for form factors, ChPT with large Nc, Flores-Mendieta, F-R, Goity

12

Two Kaon PhotoproductionA JPac effort V. Mathieu (IU), M. Shi (JLab & Peking U.), A. Szczepaniak (IU & JLab)R. Workman (GWU)

13

Motivation: SpectroscopyRemember Raúl’s talk

500

1000

1500

2000

2500

3000

i.e. AlekSejevs et al. (GlueX Collaboration), PR-13-003, PAC40 Approved

Fig. from Dudek et al. (HS Collaboration), arXiv:1309.2608 [hep-lat]

14

Dalitz Plot

Fig. taken from Peng’s talk

mpippi020.08 0.1 0.12 0.14 0.16 0.18

mpi

ppim

2

0.08

0.1

0.12

0.14

0.16

0.18

0.2

mpippim2:mpippi02 mpippim2>0&&mpippi02>0.06

sπ+π0

sπ+π−

15

Dalitz Plot

mpippi020.08 0.1 0.12 0.14 0.16 0.18

mpi

ppim

2

0.08

0.1

0.12

0.14

0.16

0.18

0.2

mpippim2:mpippi02 mpippim2>0&&mpippi02>0.06

Disclaimer: Not fully accurate comparison 15

K+K-p Dalitz PlotArtistic(?) Representation

sK+K−

sK−p

sK+K−

sK−pfixed s

γp → K+K−p16


sK+K−

sK−p

sK+K−

sK−pfixed s

Baryon

γp → K+K−p16


sK+K−

sK−p

sK+K−

sK−pfixed s

BaryonMeson

γp → K+K−p16


sK+K−

sK−p

sK+K−

sK−pfixed s

Double Regge

BaryonMeson

γp → K+K−p16


sK+K−

sK−p

sK+K−

sK−pfixed s

Double Regge

BaryonMeson

γp → K+K−p

At JLab we will be able to disentangle these three limits

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sK+K−

sK−p

sK+K−

sK−pfixed s

Double Regge

BaryonMeson

γp → K+K−p16


Double Regge

Meson

Regge phenomenologyPomeronBFKL:

Check out Andrey’s talk

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Under Construction

• We are building the pieces and putting them together

• Stay tuned

CEBAF construction© Jefferson Lab.

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pion and kaon photoproduction - jefferson lab€¦ · pion and kaon photoproduction césar...

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