REVIEW
Renormalization and Running of Quark Mass and Field in the Regularization Invariant and MS-bar Schemes at Three and Four Loops
High Energy Physics - Phenomenology · Submitted 13 Oct 1999 · 61 references
Pith's verdict: The NNNLO MS-bar→RI conversion factors are the real deliverable and they look solid; the 3 GeV advice is a heuristic the authors themselves flag as '(apparent)'.
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Referee report
The paper
The paper claims
The paper computes the three-loop conversion between MS-bar and RI quark masses and fields and argues that lattice matching should move from 2 GeV to about 3 GeV because the new third-order mass term is comparable to the second.
The reading
What carries the argument
The load-bearing object is the set of conversion equations that relate a general mass-independent scheme to MS-bar through the renormalized quark propagator. Writing the propagator as $S(q)=i/(m-/q-Sigma)$ with $Sigma=/q Sigma_V + m Sigma_S$, the RI renormalization condition sets the amputated Green function to its tree value in Landau gauge at $q^2=-mu^2$ and $m=0$. This gives $C^{RI}_2 = [1+Sigma_V + (1/2) partial Sigma_V/partial ell]^{-1}$ and $C^{RI}_m = [(1+Sigma_V + (1/2) partial Sigma_V/partial ell)/(1-Sigma_S)]$ evaluated at $q^2=-mu^2$, with $ell=log(-q^2/mu^2)$; the RI' variant drops the derivative term. The authors compute the needed massless three-loop $Sigma_V$ and $Sigma_S$ using QGRAF for diagram generation, LMP for small-mass expansion, and MINCER and MATAD for the resulting integrals. The same conversion functions then feed into $gamma'_m = gamma_m - beta, partial_{alpha_s} ln C_m$ and the analogous field equation, producing the four-loop RI anomalous dimensions. The paper's discussion of the absent $zeta(4)$ rests on defining scale- and scheme-invariant functions $Gamma^{RI}_{?}$ from the $q^2$ dependence of the conversion factor.
Extended reading notes
Core claim
The central claim is that the RI-to-MS-bar conversion for the quark mass and field is now known through order $O(alpha_s^3)$, and that this new term changes the practical advice for lattice quark-mass determinations. In Eqs. (34)-(37) the authors give explicit conversion functions $C^{RI}_m$, $C^{RI}_2$, $C^{RI'}_m$, and $C^{RI'}_2$ as polynomials in $alpha_s/(4pi)$ with coefficients depending on $n_f$. For $n_f=4$ and $alpha_s/pi=0.1$, the RI mass conversion reads $C^{RI}_m = 1.0 - 0.1333 - 0.0754 - 0.0495$ at $mu=2$ GeV: the third-order term is comparable to the second. At $mu=3$ GeV the same series becomes $1.0 - 0.111 - 0.0526 - 0.0289$, which is the basis for the recommendation to move the matching scale upward. The paper also reports that the massless approximation used for the RI conversion is poor for a charm quark near 2 GeV, because the mass-dependent MOM scheme differs from RI by terms containing $z ln z$ with $z=m^2/q^2$.
Load-bearing premise
The recommendation to move the matching scale to 3 GeV rests on the apparent shrinkage of the first three terms and assumes the uncomputed fourth-order coefficient will not reverse that pattern; the paper offers no bound or resummation for it.
Editorial extensions
If this is right
- Lattice groups that convert RI masses to MS-bar at 2 GeV should treat the missing fourth-order term as a real truncation uncertainty rather than assuming the three-loop result is precision.
- Moving the matching scale to about 3 GeV reduces the known mass-conversion series from $1.0-0.111-0.0526-0.0289$ at $alpha_s/pi=0.1$, giving a better-behaved starting point if the pattern continues.
- The four-loop RI and RI' anomalous dimensions allow consistent running of RI masses and fields and a four-loop relation between the RI mass and the renormalization-group-invariant mass for $n_f=3,4,5$.
- The absence of $zeta(4)$ in the RI and RI' anomalous dimensions, in contrast to their MS-bar counterparts, supports the interpretation that this constant is an artifact of the MS-bar scheme rather than a physical feature.
- For the charmed quark, the RI massless limit is a poor approximation near 2 GeV because mass-dependent MOM corrections enter as $z ln z$; a mass-dependent matching is needed for charm.
Reading between the lines
- A natural next step is to estimate the uncomputed four-loop coefficient with a Padé, Borel, or conformal-mapping analysis; if that estimate is small at 3 GeV, the paper's practical recommendation becomes much stronger, and if it is large, the recommendation loses its basis.
- The scheme-invariant $Gamma^{RI}_{?}$ construction could be applied to other momentum-subtraction anomalous dimensions to test whether the disappearance of $zeta(4)$ is a general property of physical MOM schemes rather than a special feature of the quark mass and field.
- A lattice systematic study that varies the matching scale from 2 to 3 GeV and propagates the conversion uncertainty into the final light-quark masses would show whether this truncation error dominates other lattice errors at current precision.
- For charm, a practical extension is to compare RI, RI', and mass-dependent MOM conversions directly at the same scale, rather than treating RI as an approximation to MOM in the charm region.
Original abstract
We derive explicit transformation formulae relating the renormalized quark mass and field as defined in the MS-bar scheme with the corresponding quantities defined in any other scheme. By analytically computing the three-loop quark propagator in the high-energy limit (that is keeping only massless terms and terms of first order in the quark mass) we find the NNNLO conversion factors transforming the MS-bar quark mass and the renormalized quark field to those defined in a ``Regularization Invariant'' (RI) scheme which is more suitable for lattice QCD calculations. The NNNLO contribution in the mass conversion factor turns out to be large and comparable to the previous NNLO contribution at a scale of 2 GeV --- the typical normalization scale employed in lattice simulations. Thus, in order to get a precise prediction for the MS-bar masses of the light quarks from lattice calculations the latter should use a somewhat higher scale of around, say, 3 GeV where the (apparent) convergence of the perturbative series for the mass conversion factor is better. We also compute two more terms in the high-energy expansion of the MS-bar renormalized quark propagator. The result is then used to discuss the uncertainty caused by the use of the high energy limit in determining the MS-bar mass of the charmed quark. As a by-product of our calculations we determine the four-loop anomalous dimensions of the quark mass and field in the Regularization Invariant scheme. Finally, we discuss some physical reasons lying behind the striking absence of zeta(4) in these computed anomalous dimensions.
The compiled record
The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.
The abstract, sentence by sentence
We derive explicit transformation formulae relating the renormalized quark mass and field as defined in the MS-bar scheme with the corresponding quantities defined in any other scheme. By analytically computing the three-loop quark propagator in the high-energy limit (that is keeping only massless terms and terms of first order in the quark mass) we find the NNNLO conversion factors transforming the MS-bar quark mass and the renormalized quark field to those defined in a ``Regularization Invariant'' (RI) scheme which is more suitable for lattice QCD calculations. The NNNLO contribution in the mass conversion factor turns out to be large and comparable to the previous NNLO contribution at a scale of 2 GeV --- the typical normalization scale employed in lattice simulations. Thus, in order to get a precise prediction for the MS-bar masses of the light quarks from lattice calculations the latter should use a somewhat higher scale of around, say, 3 GeV where the (apparent) convergence of the perturbative series for the mass conversion factor is better. We also compute two more terms in the high-energy expansion of the MS-bar renormalized quark propagator. The result is then used to discuss the uncertainty caused by the use of the high energy limit in determining the MS-bar mass of the charmed quark. As a by-product of our calculations we determine the four-loop anomalous dimensions of the quark mass and field in the Regularization Invariant scheme. Finally, we discuss some physical reasons lying behind the striking absence of zeta(4) in these computed anomalous dimensions.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | We derive explicit transformation formulae relating the renormalized quark mass and field as defined in the MS-bar scheme with the corresponding quantities defined in any other scheme. | contribution 0.93 | 0.95 | 0.15 | asserted 1.00 |
| s1 | By analytically computing the three-loop quark propagator in the high-energy limit (that is keeping only massless terms and terms of first order in the quark mass) we find the NNNLO conversion factors transforming the MS-bar quark mass and the renormalized quark field to those defined in a ``Regularization Invariant'' (RI) scheme which is more suitable for lattice QCD calculations. | contribution 0.57 | 0.97 | 0.29 | asserted 1.00 |
| s2 | The NNNLO contribution in the mass conversion factor turns out to be large and comparable to the previous NNLO contribution at a scale of 2 GeV --- the typical normalization scale employed in lattice simulations. | result 0.96 | 0.92 | 0.23 | asserted 1.00 |
| s3 | Thus, in order to get a precise prediction for the MS-bar masses of the light quarks from lattice calculations the latter should use a somewhat higher scale of around, say, 3 GeV where the (apparent) convergence of the perturbative series for the mass conversion factor is better. | interpretation 0.64 | 0.49 | 0.32 | asserted 0.50 |
| s4 | We also compute two more terms in the high-energy expansion of the MS-bar renormalized quark propagator. | contribution 0.85 | 0.96 | 0.03 | asserted 0.99 |
| s5 | The result is then used to discuss the uncertainty caused by the use of the high energy limit in determining the MS-bar mass of the charmed quark. | contribution 0.42 | 0.85 | 0.04 | asserted 0.87 |
| s6 | As a by-product of our calculations we determine the four-loop anomalous dimensions of the quark mass and field in the Regularization Invariant scheme. | result 0.91 | 0.97 | 0.12 | asserted 1.00 |
| s7 | Finally, we discuss some physical reasons lying behind the striking absence of zeta(4) in these computed anomalous dimensions. | interpretation 0.95 | 0.66 | 0.04 | asserted 0.60 |
What was examined, and what was not
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Figures
Figures reproduced from arXiv:hep-ph/9910332 by the authors.
References
How later papers used it
68 later papers cite it
5 later papers by other authors are listed below: 5 used its method or tool.
Uses its method or tool 5 of 18 papers with this label
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Computed its four-loop perturbative running of Z_q from this paper.
Renormalisation of quark propagators from twisted-mass lattice QCD at $N_f$=2 (2010) · 0.95 · paraphrased: the licence does not allow quoting
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Performed its evolution to the scale given by the charm mass at N3LO using this paper, with N_f=2.
Quark masses with Nf=2 twisted mass lattice QCD (2010) · 0.96 · paraphrased: the licence does not allow quoting
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Performed its evolution to the scale given by the charm mass at N3LO using this paper, with N_f=2.
Average up/down, strange and charm quark masses with Nf=2 twisted mass lattice QCD (2010) · 0.95 · paraphrased: the licence does not allow quoting
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Used the conversion ratio calculated by perturbation theory to 3-loops from this paper to get Z_q in the RI scheme.
Quark chiral condensate from the overlap quark propagator (2016) · 0.88 · paraphrased: the licence does not allow quoting
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Used the perturbative running and matching calculated in this paper for mass.
Step Scaling with off-shell renormalisation (2010) · 0.93 · paraphrased: the licence does not allow quoting
How the literature uses it
64 arXiv papers cite this in 101 sentences
Papers citing it · 58 sentences without a confident label
Uses its method or tool 17 papers
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We use $μ'=μ= 10$ GeV as the renormalisation scale ; $c_0Z_q^RI'(p^2,μ^2)$ is computed from the four loop perturbative running of $Z_q$ [ref] : c_0Z_q^RI'(p^2,μ^2) ≡Z_q^pert RI'(p^2, g^2_bare)/Z_q^pert RI'(μ^2, g^2_bare) ;
Renormalisation of quark propagators from twisted-mass lattice QCD at $N_f$=2 · Running including $A^2$ corrections from OPE · 0.95
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_c(2 )=1.14(3)(3) =1.14(4) → _c(_c)=1.28(4) , where the evolution to the more conventional scale given by $_c$ itself has been performed at N$^3$LO [ref] with $N_f=2$, consistently with our non-perturbative evaluation of the renormalization constant.
Quark masses with Nf=2 twisted mass lattice QCD · Charm quark mass · 0.96
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_c(2 ) = 1.14(3)(3) =1.14(4) → _c(_c) = 1.28(4) ,where the evolution to the more convential scale given by $_c$ itself has been performed at N$^3$LO [ref] with $N_f=2$, consistently with our non-perturbative evaluation of the renormalization constant.
Average up/down, strange and charm quark masses with Nf=2 twisted mass lattice QCD · Charm quark mass · 0.95
Uses its data or values 11 papers
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[ref] and the latter from ref.
Renormalisation of quark propagators from twisted-mass lattice QCD at $N_f$=2 · Appendix: The Wilson coefficients at $O(α^4)$ · 0.97
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We have used the $O(a)$-improved non-perturbative RI-MOM determination of $Z_P$, which gives $Z_P^RI-MOM(1/a) =0.39(1)(2)$ at $β=3.9$ [ref] , and converted the result to the $$ scheme at the scale $μ_R=2$ GeV by using renormalization group improved continuum perturbation theory at the N$^3$LO [ref] .
Light quark masses and pseudoscalar decay constants from Nf=2 Lattice QCD with twisted mass fermions · Physical results · 0.86
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In the quark massless limit, in Landau gauge and to three loops, the conversion ratio for $Z_S$ and $Z_P$ is [ref] [equation] where $n_f$ is the number of flavors and $ζ_n$ is the Riemann zeta function evaluated at $n$.
Non-perturbative renormalization of overlap quark bilinears on 2+1-flavor domain wall fermion configurations · Scalar density · 0.80
Compares with it 1 paper
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We see that the lattice QCD data exhibit small discretization errors and agree in the continuum limit with the perturbative counterpart $Σ_P^pt(μ_A^2,μ_B^2)=1.058$, which is computed to N$^3$LO [ref] .
Quark masses using twisted mass fermion gauge ensembles · Analysis method and safety checks against hadronic contaminations · 0.81
Cites it as background 6 papers
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The $MS$ quark-field anomalous dimension $γ_q$ (and hence $logZ_Q$) is well known [ref] .
Matching the heavy-quark fields in QCD and HQET at four loops · The QCD and HQET heavy-quark fields · 0.92
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The results for the four-loop QCD $β$-function [ref] and the four-loop quark mass and field anomalous dimensions had already been available [ref] .
Four-loop renormalization of QCD with a reducible fermion representation of the gauge group: anomalous dimensions and renormalization constants · Introduction · 0.88
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It was also shown that the former is equivalent to the $$ scheme and is thus known to three-loop order [ref] , whereas the latter is known to two-loop order [ref] .
Matching factors for Delta S=1 four-quark operators in RI/SMOM schemes · Introduction · 0.83
Discussion
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