QCD phase structure from the functional RG

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1 QCD phase structure from the functional RG Mario Mitter Ruprecht-Karls-Universität Heidelberg Dubna, November 216 M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

2 fqcd collaboration - QCD (phase diagram) with frg: J. Braun, L. Corell, A. K. Cyrol, L. Fister, W. J. Fu, M. Leonhardt, MM, J. M. Pawlowski, M. Pospiech, F. Rennecke, N. Strodthoff, N. Wink... Temperature early universe LHC quark gluon plasma RHIC SPS <ψψ> crossover FAIR/NICA <ψψ> = / vacuum hadronic fluid n B= n B> AGS SIS nuclear matter µ quark matter crossover superfluid/superconducting 2SC phases? <ψψ> = / CFL neutron star cores M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

3 fqcd collaboration - QCD (phase diagram) with frg: J. Braun, L. Corell, A. K. Cyrol, L. Fister, W. J. Fu, M. Leonhardt, MM, J. M. Pawlowski, M. Pospiech, F. Rennecke, N. Strodthoff, N. Wink... Temperature early universe LHC quark gluon plasma RHIC SPS <ψψ> crossover FAIR/NICA <ψψ> = / vacuum hadronic fluid n B= n B> AGS SIS nuclear matter µ quark matter crossover superfluid/superconducting 2SC phases? <ψψ> = / CFL neutron star cores large part of this effort: vacuum YM-theory and QCD - why? M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

4 QCD with the frg Wetterich equation with initial condition S[Φ] = Γ Λ [Φ] [Wetterich 93] k Γ k = effective action Γ[Φ] = lim k Γ k [Φ] M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

5 QCD with the frg Wetterich equation with initial condition S[Φ] = Γ Λ [Φ] [Wetterich 93] k Γ k = effective action Γ[Φ] = lim k Γ k [Φ] k : integration of momentum shells controlled by regulator full field-dependent equation with (Γ (2) [Φ]) 1 on rhs gauge-fixed approach (Landau gauge): ghosts appear mesons due to bosonization of four-fermi interaction M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

6 Low-energy effective description (PQM model) low enough momentum-scales k Λ QM : glue sector decouples remainder: quarks and mesons Γ k ΛQM [Φ] [ Z q,k q / q + h k (σ + iγ 5 τ π) q ] + [ Z σ,k σ ( 2 + mσ) 2 σ + Z π,k π ( 2 + mπ 2 ) π + Uk (σ, π) + U(Φ, Φ ) ] M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

7 Low-energy effective description (PQM model) low enough momentum-scales k Λ QM : glue sector decouples remainder: quarks and mesons Γ k ΛQM [Φ] [ Z q,k q / q + h k (σ + iγ 5 τ π) q ] + [ Z σ,k σ ( 2 + mσ) 2 σ + Z π,k π ( 2 + mπ 2 ) π + Uk (σ, π) + U(Φ, Φ ) ] additional approximations necessary: LPA: Zq,k = Z σ,k = Z π,k 1 cf. talk B.-J. Schaefer LPA : h k h [Helmboldt, Pawlowski, Strodthoff, 214] LPA +Y: all shown(!) operators run [Rennecke, Pawlowski, 214] M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

8 Low-energy effective description (PQM model) low enough momentum-scales k Λ QM : glue sector decouples remainder: quarks and mesons Γ k ΛQM [Φ] [ Z q,k q / q + h k (σ + iγ 5 τ π) q ] + [ Z σ,k σ ( 2 + mσ) 2 σ + Z π,k π ( 2 + mπ 2 ) π + Uk (σ, π) + U(Φ, Φ ) ] additional approximations necessary: LPA: Zq,k = Z σ,k = Z π,k 1 cf. talk B.-J. Schaefer LPA : h k h [Helmboldt, Pawlowski, Strodthoff, 214] LPA +Y: all shown(!) operators run [Rennecke, Pawlowski, 214] external information: Polyakov-loop potential U(Φ, Φ ) from lattice input initial h ΛQM, U ΛQM, m σ,λqm and m π,λqm from vacuum observables M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

9 Low-energy effective description (PQM model) low enough momentum-scales k Λ QM : glue sector decouples remainder: quarks and mesons Γ k ΛQM [Φ] [ Z q,k q / q + h k (σ + iγ 5 τ π) q ] + [ Z σ,k σ ( 2 + mσ) 2 σ + Z π,k π ( 2 + mπ 2 ) π + Uk (σ, π) + U(Φ, Φ ) ] additional approximations necessary: LPA: Zq,k = Z σ,k = Z π,k 1 cf. talk B.-J. Schaefer LPA : h k h [Helmboldt, Pawlowski, Strodthoff, 214] LPA +Y: all shown(!) operators run [Rennecke, Pawlowski, 214] external information: Polyakov-loop potential U(Φ, Φ ) from lattice input initial h ΛQM, U ΛQM, m σ,λqm and m π,λqm from vacuum observables usual applications Λ QM.7 1 GeV - justified? M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

10 Equation of state (EOS) pressure t = T Tc T c interactions measure correct dofs below t.2 P/T Wuppertal-Budapest, 21 PQM FRG PQM emf PQM MF (ε - 3P)/T Wuppertal-Budapest, 21 HotQCD N t =8, 212 HotQCD N t =12, 212 PQM FRG PQM emf PQM MF t t [Herbst, MM, Pawlowski, Schaefer, Stiele, 213] [Herbst, MM, Pawlowski, Schaefer, Stiele, 216] M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

11 Kurtosis [Fu, Pawlowski, 215,216], [Fu, Pawlowski, Schaefer, 216] χ B n = n p (µ B /T ) n T 4 µ( s) from freeze-out curve fluctuations in finite volume: cf. talk B.-J. Schaefer M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

12 η -meson (screening) mass at chiral crossover drop in η mass at chiral crossover? [Csörgo et al., 21] M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

13 η -meson (screening) mass at chiral crossover drop in η mass at chiral crossover? [Csörgo et al., 21] t Hooft determinant [MeV] -2.6 λ (S-P) k/[mev] RG-scale dependence from QCD [MM, Pawlowski, Strodthoff, 214] temperature dependence k(t ): λ (S P)+,QCD(k) λ (S P)+,PQM(T ) M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

14 η -meson (screening) mass at chiral crossover drop in η mass at chiral crossover? [Csörgo et al., 21] t Hooft determinant [MeV] -2.6 λ (S-P) k/[mev] RG-scale dependence from QCD [MM, Pawlowski, Strodthoff, 214] temperature dependence k(t ): λ (S P)+,QCD(k) λ (S P)+,PQM(T ) 1 screening masses 8 m/[mev] m η m ηpqm m σpqm m πpqm T/[MeV] [Heller, MM, 215] M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

15 η -meson (screening) mass at chiral crossover drop in η mass at chiral crossover? [Csörgo et al., 21] t Hooft determinant [MeV] -2.6 λ (S-P) k/[mev] RG-scale dependence from QCD [MM, Pawlowski, Strodthoff, 214] temperature dependence k(t ): λ (S P)+,QCD(k) λ (S P)+,PQM(T ) 1 8 screening masses N f = 2 + 1: [MM, Schaefer, 213] m/[mev] m η m ηpqm m σpqm m πpqm T/[MeV] [Heller, MM, 215] masses [MeV] 12 π σ a η η T [MeV] M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

16 Spectral functions [Pawlowski, Strodthoff, 215] (O(N)-model, T = ).1 pion ε=.1 sigma ε=.1 spectral function ρ[1/mev 2 ].1 1e-6 1e-8 1e-1 ρ(ω, p) = ImΓ (2) R (ω, p), ImΓ (2) R (ω, p)2 +ReΓ (2) Γ(2) R (ω, p)2 R ext. frequency ω[mev] (ω, p) = lim ɛ Γ(2) E direct calculation, no numerical analytical continuation O(4)-symmetric regularization ( i (ω + iɛ), p) M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

17 Phase structure with functional methods works well at µ = : agreement with lattice (ε - 3P)/T Wuppertal-Budapest, 21 HotQCD N t =8, 212 HotQCD N t =12, 212 PQM FRG PQM emf PQM MF t [Herbst, MM, Pawlowski, Schaefer, Stiele, 13] 1.8 Lattice set A set B l,s (T) / l,s (T=) T [MeV] [Luecker, Fischer, Welzbacher, 214] [Luecker, Fischer, Fister, Pawlowski, 13] M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

18 Phase structure with functional methods works well at µ = : agreement with lattice different results at large µ (possibly already at small µ) T [MeV] FRG emf MF µ [MeV] [MM, Schaefer, 213] 2 15 µ B /T=2 µ B /T=3 T [MeV] 1 5 Lattice: curvature range κ= DSE: chiral crossover DSE: critical end point DSE: deconfinement crossover µ q [MeV] [Luecker, Fischer, Fister, Pawlowski, 13] M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

19 Phase structure with functional methods works well at µ = : agreement with lattice different results at large µ (possibly already at small µ) calculations need model input: Polyakov-quark-meson model with frg: inital values at Λ O(Λ QCD ) input for Polyakov loop potential quark propagator DSE: IR quark-gluon vertex T [MeV] µ [MeV] FRG emf MF [MM, Schaefer, 213] µ B /T=2 µ B /T=3 T [MeV] 1 5 Lattice: curvature range κ= DSE: chiral crossover DSE: critical end point DSE: deconfinement crossover µ q [MeV] [Luecker, Fischer, Fister, Pawlowski, 13] M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

20 Phase structure with functional methods works well at µ = : agreement with lattice different results at large µ (possibly already at small µ) calculations need model input: Polyakov-quark-meson model with frg: inital values at Λ O(Λ QCD ) input for Polyakov loop potential quark propagator DSE: IR quark-gluon vertex possible explanations for disagreement: µ : relative importance of diagrams changes summed contributions vs. individual contributions µ-dependent initial values necessary in PQM/PNJL approaches T [MeV] T [MeV] µ [MeV] FRG emf MF [MM, Schaefer, 213] Lattice: curvature range κ= DSE: chiral crossover DSE: critical end point µ B /T=2 DSE: deconfinement crossover µ B /T= µ q [MeV] [Luecker, Fischer, Fister, Pawlowski, 13] M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

21 QCD with the frg... again use only perturbative QCD input α S (Λ = O(1) GeV) m q (Λ = O(1) GeV) M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

22 QCD with the frg... again use only perturbative QCD input α S (Λ = O(1) GeV) m q (Λ = O(1) GeV) Wetterich equation with initial condition S[Φ] = Γ Λ [Φ] k Γ k [A, c, c, q, q] = 1 2 effective action Γ[Φ] = lim k Γ k [Φ] M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

23 QCD with the frg... again use only perturbative QCD input α S (Λ = O(1) GeV) m q (Λ = O(1) GeV) Wetterich equation with initial condition S[Φ] = Γ Λ [Φ] k Γ k [A, c, c, q, q] = 1 2 effective action Γ[Φ] = lim k Γ k [Φ] k : integration of momentum shells controlled by regulator full field-dependent equation with (Γ (2) [Φ]) 1 on rhs gauge-fixed approach (Landau gauge): ghosts appear M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

24 Vertex expansion approximation necessary - vertex expansion Γ[Φ] = n p 1,...,p n 1 Γ (n) Φ 1 Φ n (p 1,..., p n 1 )Φ 1 (p 1 ) Φ n ( p 1 p n 1 ) M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

25 Vertex expansion approximation necessary - vertex expansion Γ[Φ] = n p 1,...,p n 1 Γ (n) Φ 1 Φ n (p 1,..., p n 1 )Φ 1 (p 1 ) Φ n ( p 1 p n 1 ) functional derivatives with respect to Φ i = A, c, c, q, q: equations for 1PI n-point functions, e.g. gluon propagator: t 1 = M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

26 Vertex expansion approximation necessary - vertex expansion Γ[Φ] = n p 1,...,p n 1 Γ (n) Φ 1 Φ n (p 1,..., p n 1 )Φ 1 (p 1 ) Φ n ( p 1 p n 1 ) functional derivatives with respect to Φ i = A, c, c, q, q: equations for 1PI n-point functions, e.g. gluon propagator: t 1 = want apparent convergence of Γ[Φ] = lim k Γ k [Φ] M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

27 Landau gauge QCD two crucial phenomena: SχSB and confinement similar scales - hard to disentangle see e.g. [Williams, Fischer, Heupel, 215] quenched QCD: allows separate investigation: M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

28 Landau gauge QCD two crucial phenomena: SχSB and confinement similar scales - hard to disentangle see e.g. [Williams, Fischer, Heupel, 215] quenched QCD: allows separate investigation: quenched matter part [MM, Strodthoff, Pawlowski, 214] outlook: unquenching [Cyrol, MM, Strodthoff, Pawlowski, in preparation] pure YM-theory (cf. talk Anton Cyrol) [Cyrol, Fister, MM, Pawlowski, Strodthoff, 216] M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

29 Chiral symmetry breaking χsb resonance in 4-Fermi interaction λ (pion pole): M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

30 Chiral symmetry breaking χsb resonance in 4-Fermi interaction λ (pion pole): resonance singularity without momentum dependency t λ = a λ 2 + b λ α + c α 2, b >, a, c t = t λ g = g =, T > g = g cr λ g > g cr [Braun, 211] M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

31 (transverse) running couplings [Cyrol, MM, Pawlowski, Strodthoff, in preparation] running couplings α X qaq cac,prop cr p [GeV] agreement in perturbative regime required by gauge symmetry non-degenerate in nonperturbative regime: reflects gluon mass gap α qaq > α cr : necessary for chiral symmetry breaking area above α cr very sensitive to errors M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

32 4-Fermi vertex via dynamical hadronization [Gies, Wetterich, 22] change of variables: particular 4-Fermi channels meson exchange efficient inclusion of momentum dependence no singularities M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

33 4-Fermi vertex via dynamical hadronization [Gies, Wetterich, 22] change of variables: particular 4-Fermi channels meson exchange efficient inclusion of momentum dependence no singularities identification of Λ QM/NJL 3 MeV k Γ k = (bosonized) 4-fermi-interaction h 2 π /(2 m2 π ) λ π RG-scale k [GeV] Yukawa interaction h π RG-scale k [GeV] [MM, Strodthoff, Pawlowski, 214] [Braun, Fister, Haas, Pawlowski, Rennecke, 214] [MM, Strodthoff, Pawlowski, 214] M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

34 Flow equations (FormTracer: cf. talk A. K. Cyrol, [Cyrol, MM, Strodthoff, 216]) [MM, Strodthoff, Pawlowski, 214], [Cyrol, Fister, MM, Strodthoff, Pawlowski, 216] 1 t = t = perm. t = 2 + perm. M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

35 Flow equations (FormTracer: cf. talk A. K. Cyrol, [Cyrol, MM, Strodthoff, 216]) [MM, Strodthoff, Pawlowski, 214], t 1 = + [Cyrol, Fister, MM, Strodthoff, Pawlowski, 216] t 1 = t = t = + perm. t = 1 2 t = perm perm. t = perm. t = 2 + perm. M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

36 Flow equations (FormTracer: cf. talk A. K. Cyrol, [Cyrol, MM, Strodthoff, 216]) [MM, Strodthoff, Pawlowski, 214], t 1 = + [Cyrol, Fister, MM, Strodthoff, Pawlowski, 216] t 1 = t = t = + perm. t = 1 2 t = perm perm. t = perm. t = 2 1 t = perm. t = perm. M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

37 YM theory [Cyrol, Fister, MM, Pawlowski, Strodthoff, 216] Γ (2) AA (p) Z A(p) p 2 ( δ µν p µ p ν /p 2) running couplings gluon propagator dressing FRG, scaling FRG, decoupling Sternbeck et al. running couplings α Acc α A 3 α A p [GeV] p [GeV] more details Talk Anton K. Cyrol lattice data: A. Sternbeck, E. M. Ilgenfritz, M. Muller-Preussker, A. Schiller, and I. L. Bogolubsky, PoS LAT26, 76. M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

38 Quark propagator [MM, Pawlowski, Strodthoff, 214] Γ (2) qq (p) Z q(p) (/p + M(p)) quark propagator dressings Bowman et al., 5 1/Z q M q p [GeV] frg vs. lattice: bare mass, quenched, scale set via gluon propagator agreement not sufficient: need apparent convergence at µ lattice data: Bowman, Heller, Leinweber, Parappilly, Williams, Zhang, Phys. Rev. D71, 5457 (25). M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

39 Outlook: unquenching extended truncation: [Cyrol, MM, Pawlowski, Strodthoff, in prep.] Γ (2) AA (p) Γ(2) cc (p) Γ (3) A cc (psym) Γ (3) (psym) A 3 Γ (4) (psym) A 4 classical tensor classical tensor Γ(2) Γ (3) qq (p) A qq (p, q) Γ(4) Γ (5) Γ (4) AA qq (psym) (psym) A3 qq q qqq(p, p, p) q /D n q complete, n 3 mom. ind. tensors φ1 φn Γ(2) φφ (p) φ {σ, π} Γ (3) qqφ (p, p) Γ (4) qqφφ (psym) Γ(5) qqφ 3 (psym) n {3,..., 12} Γ(n) φ n () classical tensor classical tensor classical tensor systematics of improving the truncation? M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

40 Outlook: unquenching extended truncation: [Cyrol, MM, Pawlowski, Strodthoff, in prep.] Γ (2) AA (p) Γ(2) cc (p) Γ (3) A cc (psym) Γ (3) (psym) A 3 Γ (4) (psym) A 4 classical tensor classical tensor Γ(2) Γ (3) qq (p) A qq (p, q) Γ(4) Γ (5) Γ (4) AA qq (psym) (psym) A3 qq q qqq(p, p, p) q /D n q complete, n 3 mom. ind. tensors φ1 φn Γ(2) φφ (p) φ {σ, π} Γ (3) qqφ (p, p) Γ (4) qqφφ (psym) Γ(5) qqφ 3 (psym) n {3,..., 12} Γ(n) φ n () classical tensor classical tensor classical tensor systematics of improving the truncation? BRST-invariant operators, e.g. ψ /D n ψ M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

41 Outlook: running couplings α cac = α AAA = α A 4 = ( ) Γ (3) 2 cac (p) 4π Z A (p)z c(p) 2 ( Γ (3) AAA (p) ) 2 4π Z A (p) 3 ( Γ (4) A 4 (p) ) 4π Z A (p) 2 running couplings α X α qaq = [Cyrol, MM, Pawlowski, Strodthoff, in preparation] ( Γ (3) qaq (p) ) 2 4π Z A (p)z q(p) 2 α cac,prop = 1 4π Z A (p)z c(p) 2 cac AAA A 4 qaq cac,prop p [GeV] M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

42 Outlook: gluon propagator [Cyrol, MM, Pawlowski, Strodthoff, in preparation] gluon propagator dressing 1/Z A Sternbeck et al. FRG p [GeV] lattice data: A. Sternbeck, K. Maltman, M. Müller-Preussker, L. von Smekal, PoS LATTICE212 (212) 243. M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

43 Outlook: quark propagator [Cyrol, MM, Pawlowski, Strodthoff, in preparation] quark propagator dressings lattice, m π =28 MeV m π =295 MeV.4 FRG, m π = p [GeV] comparison frg with lattice: bare mass and scale setting lattice data: Orlando Oliveira, Kzlersu, Silva, Skullerud, Sternbeck, Williams, arxiv: [hep-lat]. M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

44 Summary and outlook low-energy effective descriptions with frg: EOS, kurtosis, axial anomaly, spectral functions, phase structure,... low-energy models can be improved with QCD input M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

45 Summary and outlook low-energy effective descriptions with frg: EOS, kurtosis, axial anomaly, spectral functions, phase structure,... low-energy models can be improved with QCD input vacuum QCD from the frg: sole input αs (Λ = O(1) GeV) and m q (Λ = O(1) GeV) vertex expansion: good agreement with lattice correlators M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

46 Summary and outlook low-energy effective descriptions with frg: EOS, kurtosis, axial anomaly, spectral functions, phase structure,... low-energy models can be improved with QCD input vacuum QCD from the frg: sole input αs (Λ = O(1) GeV) and m q (Λ = O(1) GeV) vertex expansion: good agreement with lattice correlators Outlook QCD phase diagram: order parameters, equation of state and fluct. of cons. charges (T, µ)-dependent input for effective low-energy descriptions bound-state properties (form factors,pda... ) more checks on convergence of vertex expansion M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

47 Summary and outlook low-energy effective descriptions with frg: EOS, kurtosis, axial anomaly, spectral functions, phase structure,... low-energy models can be improved with QCD input vacuum QCD from the frg: sole input αs (Λ = O(1) GeV) and m q (Λ = O(1) GeV) vertex expansion: good agreement with lattice correlators Outlook QCD phase diagram: order parameters, equation of state and fluct. of cons. charges (T, µ)-dependent input for effective low-energy descriptions bound-state properties (form factors,pda... ) more checks on convergence of vertex expansion M. Mitter (U Heidelberg) QCD phase structure from the frg Dubna, November / 23

Chiral symmetry breaking in continuum QCD

Chiral symmetry breaking in continuum QCD Mario Mitter Ruprecht-Karls-Universität Heidelberg Trieste, September 206 M. Mitter (U Heidelberg) χsb in continuum QCD Trieste, September 206 / 20 fqcd collaboration