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Y. Sumino (Tohoku Univ.) Basics of potential-NRQCD and Quarkonium Spectroscopy
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Heavy Quarkonium: ? For, bound-state theory based on pert. QCD is valid. gluons with decouples Appropriate EFT NRQCD potential NRQCD (pNRQCD) velocity NRQCD (vNRQCD) Caswell, Lepage Pineda, Soto Manohar, Stewart
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Virtue of EFT Principle sym. & small parameter Constrain possible interactions Systematic expansion Matching to full theory OPE (separating pert. vs non-pert. effects) Wilson coeffs.Matrix elements of operators cf. Chiral PT
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Relevant d.o.f. and interacting via potential(s) + IR gluons (ultrasoft gluons) To undestand systematic expansion, consider hydrogen-like atom (pNRQED) Bohr radius Bound-stateIR photon All other (short-dist.) modes are “integrated out” Effects incorporated into Wilson coefficients=“potentials”. Expansion parameters:
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Lagrangian where should be expanded in. Field redefinition gauge singlet Expansion parameters:
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Lagrangian gauge inv. at each order of -expansion : electric field at LO Lagrangian dipole interaction … US photon e.g. Lamb shift with Propagator of hydrogen-like atom in QM:
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Systematic expansion in “Potential”=Wilson coeff.: function of Non-Local in Local in Integrating out
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Potential-NRQCD and OPE of QCD potential QCD potential: as : OPE: expansion in Brambilla, Pineda, Soto, Vairo IR contr.UV contr. singlet octet singlet US gluon
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OPE: expansion in Brambilla, Pineda, Soto, Vairo IR contr.UV contr. singlet octet singlet US gluon
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OPE: expansion in Brambilla, Pineda, Soto, Vairo IR contr.UV contr. singlet octet singlet US gluon : Wilson coeff.,, perturbative : non-pert. matrix element + Potential NRQCD is valid below cut-off scale, where. prediction of OPE and pert. QCD non-pert. matrix element Folklore: pert., non-pert. Wrong at r < 0.5 fm !
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Y.S. Accuracy of perturbative prediction of improved drastically around 1998, due to discovery of renormalon cancellation in. Hoang, Smith, Steltzer, Willenbrock; Beneke
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Application to quarkonium spectroscopy and determination of. Global level structure of bottomonium is reproduced. Brambilla, Sumino, Vairo Determination of bottom and charm quark MS masses: Brambilla, Sumino, Vairo Fine and hyperfine splittings of charmonium/bottomonium reproduced. In particular, mass of is predicted correctly. Recksiegel, Y.S. However, mass of disagrees: Relation between lattice and MS is accurately measured (quenched approx.) Y.S. Recksiegel, Y.S (prediction) (exp.09)
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D.o.f. that are integrated out in pNRQCD: hard (, + gluon): soft (, + gluon): potential (gluon): No other scales are known to play roles in Coulombic bound-states. Beneke, Smirnov potential (, ): ultrasoft (gluon): Dynamical d.o.f. in pNRQCD:
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3. QCD Potential: OPE Analysis at §
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QCD Potential: Pert. QCD
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Lattice QCD: Determination of
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OPE of Wilson coeff. non-pert. contr. cancel
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