Sitting in the Interphase: Connecting Experiment and Theory in Nuclear and Hadronic Physics

Transcription

1 Sitting in the Interphase: Connecting Experiment and Theory in Nuclear and Hadronic Physics César Fernández-Ramírez Nuclear Physics Group, Universidad Complutense de Madrid Indiana-JLab Interview, 11th January 213

2 Biographical Presentation

3 Biography (I) Born in Madrid, Spain on March 13, Licenciado (5yr) in Physics (Theoretical) Universidad Complutense de Madrid (UCM) MSc in Atomic and Nuclear Physics UCM 23 Fellow of the Marie Curie Training program on Nuclear Structure at ECT* (Trento) PhD Structure of Matter Institute (Spanish Council for Scientific Research) defended at UCM Title: Electormagnetic Production of Light Mesons Supervisors: Prof. E. Moya de Guerra and Prof. J.M. Udías

4 Biography (II) 27 Researcher associated to a project Nuclear Physics Group, UCM Electron scattering and kinematics calculations for planned experiments at FAIR/GSI (ELISe and EXL collaborations) with Prof. J.M. Udías Spanish Ministry of Science and Technology Postdoctoral Fellow CTP and LNS, MIT with Prof. T.W. Donnelly and Prof. A.M. Bernstein working on near-threshold pion photoproduction and HBChPT Postdoc Research Associate ECT* (Director: Prof. Achim Richter) Independent researcher, pion photoproduction and hadron spectroscopy 211-? Spanish Government Juan de la Cierva Research Fellow Nuclear Physics Group, UCM Independent researcher, pion photoproduction and hadron spectroscopy

5 Teaching Experience UCM, Master Erasmus Mundus in Nuclear Fusion Science and Engineering Physics: Computational Physics: 1/11, 11/12, & 12/13 UCM, Degree in Physics: Physics Lab: 1/11, 11/12 Nuclear and Particle Physics: 4/5 UCM, Degree in Chemistry: General Physics: 12/13 UCM, One Master thesis supervised within the Inter- University Nuclear Physics Master Program. Chaos in Hadrons 11/12

6 Research

7 Research Pion photoproduction from the Nucleon in the Resonance Region Pion Production from Nuclei Near-Threshold Pion Photoproduction Quantum Chaos in Hadrons Experimental Physics

8 3/2 Re[M 1+ ] (mf) p Re[E + ] (mf) /2 Im[M 1+ ] (mf) E (GeV) p Im[E + ] (mf) E (GeV) Pion Photoproduction from the Nucleon in the Resonance Region

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10 Pion Photoproduction Model in the Resonance Region PhD thesis Up to 1.8 GeV of invariant mass Effective Lagrangian Approach 8 Resonances, Spin 1/2 and 3/2 Consistent Spin-3/2 treatment Crossing symmetric Straightforward extension to nuclei Full model published in Ann. Phys. (N.Y.) 321 (26)

11 p E + (mf) Real part Imaginary part Pion Photoproduction from the Nucleon 4 p M 1- (mf) /2 M 1+ (mf) /2 E 1+ (mf) E (GeV) Examples of the isospin-3/2 and Isospin-1/2 proton channels

12 Highlights Development of Lagrangians for D 33, D 13 and P 13 resonances [Ann. Phys. (NY) 321 (26) 148] Study of the Δ(1232) electromagnetic deformation within a consistent spin-3/2 framework [Phys. Rev. C 73 (26) 4221(R), Eur. Phys. J. A 31 (27) 572] Impact of crossing symmetry in phenomenological models [Phys. Lett. B 66 (28) 188] Reliability of resonance inclusion and parameter assessment employing novel fitting techniques (genetic algorithms) [Phys. Rev. C 77 (28) 65212] Testing SU(3) chiral symmetry through pseudovectorpseudoscalar mixing in eta photoproduction [Phys. Lett. B 651 (27) 369]

13 Electromagnetic probe Ejected pion Nucleons Nucleus Pion Production from Nuclei

14 16 O(γ,π - p) Reaction in the Δ region: Previous Analysis Pion photoproduction model SAID: Factorization Nuclear model: Harmonic oscillator Conclusion: Medium modifications

15 16 O(γ,π - p) Reaction in the Δ region: Improved Analysis Pion photoproduction model: Effective Lagrangian No Factorization and consistent Δ =36 o =44 o =52 o =6 o =68 o =76 o.6 Nuclear model: Relativistic Mean Field =84 o =92 o =1 o.2 Conclusion: No medium modifications needed for this observable =18 o =132 o =116 o =14 o =124 o p (deg) p (deg) p (deg) 75 9 [Phys. Lett. B 664 (28) 57]

16 Currently working on Reaction Model for Primakoff Effect 28 Pb(γ,π ) and 12 C(γ,π ) High-energy pion photoproduction Forward angle Full pion rescattering Lagrangian approach No factorization Nuclear transitions (arbitrary nuclear model)

17 Why? Pion lifetime Chiral symmetry breaking Very important to count with a reliable and accurate reaction model Once the model is built, adapt to other processes is straightforward d /d (!b/rad) E =5.2 GeV, 12 C, elastic (deg) I. Sick 1s 1/2 1p 3/2 1s 1/2 +1p 3/2

18 Why Nuclear Physics Matters Although the photon energy is high......the momentum exchange is low And nuclear effects show up through: Ground state (elastic channel) Excited states (inelastic channels)

19 3 Bernard et al. 2 a - (GeV -4 ) 1 SP x 9% -1 7% SPD a + (GeV -4 ) Near-Threshold Pion Photoproduction

20 Why Near-Threshold Pion Photoproduction? Chiral Symmetry in the Baryon sector Unitarity (testing against Compton and Pion-Nucleon Scattering) Chiral Perturbation Theory Important research programs at MAMI and JLab (electroproduction)

21 partial waves In most of hadronic processes First S wave contributes Then P waves and the rest of partial waves add up orderly Neutral pion photoproduction S wave is very weak P waves are strong due to Δ(1232) appearance D waves contribute due to the weakness of the S wave

22 D waves Impact in CHPT No impact in P waves extraction Up to a 2% impact at the cusp in the S wave extraction Besides, the S wave is the most interesting partial wave regarding chiral symmetry breaking

23 D waves Impact in CHPT No impact in P waves extraction 3 Bernard et al. 2 Up to a 2% impact at the cusp in the S wave extraction a - (GeV -4 ) 1 SP x 9% Besides, the S wave is the most interesting partial wave regarding chiral symmetry breaking % SPD a + (GeV -4 )

24 D waves Impact in CHPT No impact in P waves extraction Up to a 2% impact at the cusp in the S wave extraction Besides, the S wave is the most interesting partial wave regarding chiral symmetry breaking Re E + (1-3 /M +) E (GeV)

25 D waves Impact in CHPT No impact in P waves extraction Up to a 2% impact at the cusp in the S wave extraction Besides, the S wave is the most interesting partial wave regarding chiral symmetry breaking SPD/SP (%) E (GeV)

26 Full analysis We provided a full analysis of the observables structure in the near-threshold region and the impact of D waves within different theoretical approaches We studied what could be measured and suggested new observables to measure [Phys. Rev. C 8 (29) 6521] We also proved that you could ignore partial waves higher than D

27 Working with the A2 Collaboration at Mainz Energy dependence of the photon asymmetry in the near-threshold region was measured for the first time, providing an unprecedented insight on chiral symmetry Dr. L. Tiator and I made the energyindependent PWA I made the energy-dependent PWA employing empirical approach and HBChPT

28 Observable expansion σ T (W, θ) q π k γ W T (W, θ) Σ (W, θ) W S (W, θ) W T (W, θ) W T (W, θ) T (W )+T 1 (W ) P 1 (θ)+t 2 (W ) P 2 (θ)+t 3 (W ) P 3 (θ)+t 4 (W ) P 4 (θ) W S (W, θ) [S (W )+S 1 (W ) P 1 (θ)+ S 2 (W ) P 2 (θ)]sin 2 θ

29 Extracting t, t1, t2, s, s1 T (1-6 /M 2 + ) (a) T 1 (1-6 /M 2 + ) T 2 (1-6 /M 2 + ) E (MeV) (b) (c) S (1-6 /M 2 + ) E (MeV) S 1 (1-6 /M 2 + ) (d) (e) E (MeV) Restricts us to 4 single-energy partial waves Re E +, Re E 1+, Re M 1+, Re M 1- (Re E +, Re P 1, Re P 2, Re P 3 )

30 Multipole Description Empirical F-R, Bernstein, Donnelly, PRC8, 6521 (212) HBChPT Bernard, Kaiser, Meiβner, Z. Phys. C7, 483 (1996); EPJA11, 29 (21) Unitary HBChPT F-R, Bernstein, submitted, arxiv: [nucl-th] BChPT Hilt, Scherer, Tiator, to be submitted (213)

31 Fits Empirical HBChPT U-HBChPT BChPT 2 /dof E max (MeV) Amount of experimental data

32 Results Successfully extracted S an P waves Chiral Perturbation Theory without Δ works up to 17 MeV (Both Relativistic and Heavy Baryon) While empirical fits work up to 185 MeV Re P Re P Re P Re E + (1-3 1 /q (1-3 /m 2 +) 2 /q (1-3 /m 2 /m +) +) 3 /q (1-3 /m 2 +) -.2 (a) (b) (c) (d) E (MeV)

33 Ongoing research New MAMI data on pion photoproduction data in the delta region New MAMI data for the F and T asymmetries both in the near-threshold and delta regions Involved in both PWA

34 P(s) Data D Wigner D Poisson D Berry Robnik s Quantum Chaos in Hadrons

35 Quantum Chaos in Hadrons In 23 V. Pascalutsa studied the experimental hadron spectrum and found traces of chaotic behavior Started this research line in 26 by combining hadronic physics with spectral-statistics analyses inherited from Quantum Chaos Very low statistics, so new techniques had to be developed (distorted distributions) 1st publication PRL 98, 621 (27)

36 1 First Results P(s) Log 1 F(x) x (a) Experimental values from PDG (set EXP). s 1 Baryon spectrum is Wigner-like Constituent quark models for baryons are Poisson-like CQMs for baryons are incompatible with experiment P(s) Log 1 F(x) s 1 2 (b) Model by Capstick and Isgur (set CI). (c) P(s) Model by Loring P(s) Log 1 F(x) s et al. (set L1). Log 1 F(x) x 1 2 x 1 2 x (d) Model by Loring et al. s (set L2).

37 Ongoing Research We have improved the statistical techniques Now, we have very robust techniques Expanded the analysis to the meson sector (which is also Wigner-like) [Phys. Lett. B 71 (212) 139] Long paper on the hadron spectrum and the techniques is in the works

38 Mesons Experimental spectrum is closer to a Wigner distribution Quark model by Vijande et al. is the only one that is close to experiment P(s) s Lattice is closer to a Poisson distribution P(s) s s

39 What for? Agreement between theory and experiment Problem of missing states Insight on the properties of the strong interaction in the low-energy regime Help to guide effective interactions Collaborating with quark-model researchers in order to assess which interactions rise right properties Vijande et al. 25 Poisson 211 (almost) Wigner The difference is the confinement interaction

40 Experimental Physics

41 Physics at FAIR/GSI Member of the ELISe and EXL collaborations Listed in the EXL technical report [M. Chartier et al. (25)] For the ELISe collaboration, co-author in the conceptual design study: [Nucl. Inst. Meth. A 637 (211) 6] So far, provided kinematical analysis input for the experiments

42 Physics at JLab Member of the Hall A collaboration since 25 Involved in theoretical support to experiments and in actual experiments [Phys. Rev. Lett. 15 (21) 26232] E2-13, Neutron form factor measurement E4-7, π electroproduction as a test of chiral symmetry E5-11, Coulomb Sum Rule E6-7, Impulse approximation in Lead

43 And That s It, so Far César Fernández-Ramírez Nuclear Physics Group, Universidad Complutense de Madrid Indiana-JLab Interview, 11th January 213

44 Backup

45 / 2 min (1232) A 1/2 (GeV -1/2 ) (GeV -1/2 ) A 1/ / 2 min A 3/2 (GeV -1/2 ) A 3/2 (GeV -1/2 ) Assessing the Δ(1232) parameters with a genetic algorithm

46 multipoles T n (s) = ij S n (s) = ij Re{M i (s) T ij n M j (s) } Re{M i (s) S ij n M j (s) } M j (s) =E +,E 1+,E 2+,E 2,M 1+,M 1,M 2+,M 2.

47 multipole structure T =S S + P P + D D + F F +... T 1 =S P + P D + D F + F G +... T 2 =S D + P P + D D + P F +... T 3 =P D +... T 4 =D D +... S =P P + S D +... S 1 =P D +... S 2 =D D +...

48 Example: t1 T 1 E+ E1+ E2+ E2 M1+ M1 E M2+ M2 E /5 3/5 9/5 9/5 E 2+ 72/5 E 2 3/5 1 1 M /5 3/5 M M 2+ 9/5 27/5 M 2 9/5 3/5 3

49 Single-Energy Multipoles Single-energy extraction Almost model independent Im E + fixed through unitarity (next slides) Im P i = D waves = Born Terms Re P Re P Re P Re E + (1-3 1 /q (1-3 /m 2 +) 2 /q (1-3 /m 2 /m +) +) 3 /q (1-3 /m 2 +) -.2 (a) (b) (c) (d) E (MeV)

50 Unitary Cusp E + =e iδ [A + iβq + /m π +];W>W thr (π + n) E + =e iδ [A β q + /m π +];W<W thr (π + n) β = E + (γp π + n) a(π + n π p) ReE + (γp π + n) = (28.6 ±.27 ±.45) 1 3 /m π + a(π p π n)= (.122 ±.2)/m π + a(π + n π p)= a(π p π n) a(π + p π p)= (.1195 ±.16)/m π +

51 Unitarity Im E + (W )=β q π + (W ) m π HBCHPT BCHPT UNITARY Im E + (1-3 /M +) 2 β =(3.44 ±.8) 1 3 /m π + Unitary IS β =(3.35 ±.8) 1 3 /m π + Unitary ISB β = /m π + HBChPT β = /m π + BChPT E (MeV) BChPT: Hilt, Scherer, Tiator, private communication

52 empirical Fit Taylor expansion in the partial waves + S wave cusp Unitarity is respected in the S wave 8 parameters (2 per partial wave) P waves are real D waves: Born terms E + = E () + + E(1) + P i /q = P () i m π + + P (1) i ω m π m π + + iβ q π + m π + ω m π m 2 π + ; i =1, 2, 3

53 empirical Fit Chiral symmetry is not incorporated in this approach v.g. exact chiral symmetry in the S wave E + = E () + + E(1) + ω m π m π + + iβ q π + m π + + = β qthr π + E () m π +

54 LECs (HBChPT) (a) 3 25 (b) a + (GeV -4 ) a - (GeV -4 ) E max (MeV) E max (MeV) 1 (adimensional) (c) 2 (adimensional) (d) b p (GeV -3 ) (e) E max (MeV) E max (MeV) E max (MeV)