Hadron Spectroscopy Alessandro Pilloni Hadronic Physics with Lepton - - PowerPoint PPT Presentation
JPAC program for Hadron Spectroscopy Alessandro Pilloni Hadronic Physics with Lepton and Hadron Beams, JLab, September 5 th , 2017 Hadron Spectroscopy Hybrids Tetraquark Meson Baryon Glueball / Hadroquarkonium
Hadronic Physics with Lepton and Hadron Beams, JLab, September 5th, 2017
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Molecule Tetraquark Hybrids
π²/π π π π
Hadroquarkonium Glueball Meson Baryon
Data Fundamental properties, Model building
Interpretations on the spectrum leads to understanding fundamental laws of nature
Experiment Lattice QCD
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Data Fundamental properties, Model building
XYZ states Esposito, AP, Polosa, Phys. Rept. 668
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Data Fundamental properties, Model building
XYZ states Esposito, AP, Polosa, Phys. Rept. 668
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Data
Improvement needed! With great statistics comes great responsibility!
Fundamental properties, Model building
XYZ states Esposito, AP, Polosa, Phys. Rept. 668
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the best use of the next generation of very precise data taken at JLab and in the world
Effective Field Theories Analyticity+Unitarity Dispersion Relations Regge Theory Fundamental parameters Resonances, exotic states
Insight on QCD dynamics
Experiments CLAS, GlueX, BESIII, COMPASS, LHCb, BaBar, Belle II, KLOE, MAMI Lattice
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(IU), E. Passemar, A. Szczepaniak (IU/JLab)
Students, Postdocs, Faculties
(Krakow)
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documented on interactive portals
physics, conventions, formalism, etc.
codes with detailed explanation how to use them. Users can run codes online, change parameters, display results. http://www.indiana.edu/~jpac/
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These are constraints the amplitudes have to satisfy, but do not fix the dynamics Resonances (QCD states) are poles in the unphysical Riemann sheets
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Hu, Mai, Doring, AP, Szczepaniak, EPJA, arXiv:1707.06118 See M. Doringβs talk at 11:30am The full implementation of three-body unitarity is a major step for understanding the states appearing in such final states
e.g. π1 1260 + β π+πβπ+, π1 1400 + β π+πβπ+, π 3872 β πΈ0πΈ0π0
We completed the proof of the Amado model, based on the isobar approximation and a Bethe-Salpeter ansatz for the amplitude
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I sheet II sheet
Bound states on the real axis 1st sheet Not-so-bound (virtual) states on the real axis 2nd sheet
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More complicated structure when more thresholds arise: two sheets for each new threshold
III sheet: usual resonances IV sheet: cusps (virtual states) I sheet II sheet Bound state Virtual state Resonance
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One can test different parametrizations of the amplitude, which correspond to different singularities β different natures
Szczepaniak, PLB747, 410 π πΈ1 π πΈβ π πΎ/π πΈ
Triangle rescattering, logarithmic branching point (anti)bound state, II/IV sheet pole (Β«moleculeΒ») Resonance, III sheet pole (Β«compact stateΒ»)
Tornqvist, Z.Phys. C61, 525 Swanson, Phys.Rept. 429 Hanhart et al. PRL111, 132003 Maiani et al., PRD71, 014028 Faccini et al., PRD87, 111102 Esposito et al., Phys.Rept. 668
AP et al. (JPAC), PLB772, 200
ππ 3900 ? πΈ1(2420) π£: πΈ0(2400) π£: ππ 3900 ? "π, π
0(980)"
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resonant behavior, only in very special kinematical conditions (Coleman and Norton, Nuovo Cim. 38, 438)
(Schmid, Phys.Rev. 154, 1363)
you might still see peaks in other channels!
π(4260) πΈ1 π πΈβ π πΎ/π πΈ
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The scattering matrix is parametrized as π’β1 ππ = πΏππ β π ππ πππ Four different scenarios considered:
ππ ππ π2βπ‘, this generates a pole in the closest unphysical sheet
the rescattering integral is set to zero
are not normalized anyway β but not the position of singularities. This also limits the number of free parameters
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Triangle IV sheet pole Triangle III sheet pole Triangle no pole Different lineshapes according to different singularities III+tr. IV+tr. tr.
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III+tr. IV+tr. III tr. Naive loglikelihood ratio test give a βΌ 4π significance of the scenario III+tr. over IV+tr., looking at plots it looks too much β better using some more solid test
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III+tr. IV+tr. III Not conclusive at this stage
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To exclude any rescattering mechanism, we propose to search the π
π(4450) state in
photoproduction We use the (few) existing data and VMD + pomeron inspired bkg to estimate the cross section Hiller Blin, AP et al. (JPAC), PRD94, 034002 πΎπ = 3/2 β
GlueX data coming soon!
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Reggeons are poles in π for fixed π‘ dominate high energy region Resonances are poles in π‘ for fixed π dominate low energy region π΅π βΌ π1π2 π‘π β π‘ π΅ βΌ β π‘π βΌ πΎ π’ π‘π½(π’)
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See J. Nys talk at 12pm
PWA in the low energy region Resonance extraction Regge exchanges at high energy
Analytically connected
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β² show up
Resonant content The denominator πΈ(π‘) contains all the Final State Interactions constrained by unitarity β universal The numerator π(π‘) depends on the exchanges β process-dependent, smooth
Precise determination
Smooth Β«backgroundΒ»
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to estimate the systematic dependence on coupled-channel effects
variation of the number of terms in π(π‘), and in the barrier factor radius π‘π
as well as the extention to the GlueX production mechanism and kinematics
Thank you
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to make the best use of the next generation of very precise data taken at JLab and in the world
first principles of QFT (unitarity, analyticity, crossing symmetry, low and high energy constraints,β¦) to extract the physics out of the data
for high energy observables), with a particular attention to producing complete reaction models for the golden channels in exotic meson searches
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FESR
arXiv:1708.07779 π π β π π π
arXiv:1707.02848 πΏ π β π π vs. β πβ² π
arXiv:1704.07684 ππ(3900)
PLB772, 200 πΏ π β π π
PRD95, 034014 πΏ π β πΎ/π π
PRD94, 034002 πΏ π β πΏ π
PRD93, 034029; PRD93, 074015 πΏ π β π0 π
PRD92, 074013 π π β π π
PRD92, 074004 π β π+ πβ π0
PRD92, 054016; PLB771, 497 π, π β π+ πβ π0
PRD91, 094029 πΏ π β πΏ+ πΏβ π
PRD91, 034007
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ππ 3900 ? πΈ1(2420) π£: πΈ0(2400) π£: ππ 3900 ? "π, π
0(980)"
Khuri-Treiman
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AP et al. (JPAC), arXiv:1612.06490
β we are not able to give the absolute normalization of the amplitudes
independent parameters
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AP et al. (JPAC), PLB772, 200
except the peaking background in πΈ0πΈβ0, πΈβ0πΈ0 (subtracted)
not constraining enough β we do not include in the fit
couplings, which are not normalized anyway β but not the position of singularities. This also limits the number of free parameters
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Toy experiments according to the different hypotheses, to estimate the relative rejection of various scenarios Not conclusive at this stage
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We start from 2β +, long standing puzzle about π2 1670 β π2(1880) interplay
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We start from 2β +, long standing puzzle about π2 1670 β π2(1880) interplay
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Test factorization on the simplest cases
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Mathieu et al. (JPAC), PRD92, 074013
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Mathieu (JPAC), in progress
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Coupled-channel K matrix model (up to 13 channels per partial wave), analyticity in angular momentum enforced, fit to KSU partial waves One of the Ξ(1405) poles is out of the trajectory β non 3-q state Fernandez-Ramirez et al. (JPAC), PRD93, 034029 Fernandez-Ramirez et al. (JPAC), PRD93, 074015
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Szczepaniak and Pennington, PLB737, 283