Two-Loop Anomalous Dimensions in the LEFT: Dimension-Six Four-Fermion Operators in NDR
Pith reviewed 2026-05-23 04:57 UTC · model grok-4.3
The pith
The complete two-loop anomalous dimension matrix for all dimension-six four-fermion operators in the LEFT has been derived in the NDR scheme.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
By combining known two-loop ultraviolet poles in QCD with an extended treatment of gamma5 traces in the NDR scheme, the authors obtain the complete two-loop anomalous dimension matrix for the full set of dimension-six four-fermion operators in the JMS basis of the LEFT, including all O(alpha_s^2), O(alpha_s alpha), and O(alpha^2) entries, and present the matrix explicitly for LEFT with five, four, and three active quark flavors.
What carries the argument
The two-loop Anomalous Dimension Matrix (ADM) for four-fermion operators in the JMS basis, obtained by feeding known QCD UV poles into an extended NDR gamma5-trace procedure.
If this is right
- Wilson coefficients of four-fermion operators can now be evolved from a high scale to the electroweak or hadronic scale with full two-loop accuracy in both QCD and QED.
- Global fits to flavor observables that rely on LEFT can incorporate the new mixing effects at order alpha_s^2 and mixed orders.
- The results apply directly to LEFT realizations with five, four, or three active quark flavors without further calculation.
- The matrix has been encoded in DsixTools, allowing immediate numerical use in matching and running routines.
Where Pith is reading between the lines
- Higher-order matching conditions from specific ultraviolet models onto the LEFT can now be run down with reduced theoretical uncertainty from operator mixing.
- Similar techniques may allow two-loop anomalous dimensions to be obtained for other classes of dimension-six operators once their one-loop mixing is known.
- Discrepancies between LEFT predictions and data at the percent level could be re-examined with the new two-loop running to check whether they persist.
Load-bearing premise
The known two-loop UV pole results from QCD diagrams remain valid when inserted into the LEFT calculation and the extension of the gamma5 handling method correctly reproduces the NDR scheme.
What would settle it
An independent two-loop calculation of any single entry in the anomalous dimension matrix, performed in a different regularization scheme such as dimensional reduction, that yields a numerically different coefficient from the one reported here.
read the original abstract
We derive the complete set of two-loop anomalous dimensions describing the mixing of four-fermion operators in the Low Energy Effective Field Theory (LEFT). The calculation is performed in Naive Dimensional Regularization with anticommuting $\gamma_5$ (the NDR scheme), and the results are given in the "JMS basis" of dimension-six operators. The derivation relies on known results for UV poles in two-loop diagrams in QCD, which are then used to derive the two-loop Anomalous Dimension Matrix (ADM) for the full set of four-fermion operators including $O(\alpha_s^2)$, $O(\alpha_s\alpha)$ and $O(\alpha^2)$ corrections. The method employed is an extension of a common approach to deal with traces containing $\gamma_5$ in NDR. Our results have been implemented in the public code DsixTools. We also discuss and provide the results in the LEFT with 5, 4 and 3 active quark flavors.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript derives the complete two-loop anomalous dimension matrix for the mixing of dimension-six four-fermion operators in the Low Energy Effective Field Theory (LEFT) in the Naive Dimensional Regularization (NDR) scheme with anticommuting γ5. Results are given in the JMS basis and cover the O(α_s²), O(α_s α), and O(α²) sectors by feeding known two-loop QCD UV poles into the LEFT operator basis; an extension of the standard NDR γ5 trace method is employed. The calculation is performed for 3, 4, and 5 active quark flavors, with all results implemented in the public DsixTools code.
Significance. If correct, the results supply a necessary ingredient for NNLO precision calculations in the LEFT, which is central to flavor-physics phenomenology and BSM searches. The public code release constitutes a clear strength, enabling direct reproducibility and independent checks of algebraic or scheme-dependent errors. The reuse of established UV-pole results and the explicit treatment of multiple flavor thresholds further increase the practical value of the work.
minor comments (2)
- [Introduction] The manuscript would benefit from an explicit statement, perhaps in the introduction or results section, of how the chosen NDR γ5 extension differs from the prescriptions used in the input two-loop QCD calculations.
- [Results] A short table or paragraph comparing the new two-loop entries with the known one-loop ADM (for at least one representative operator) would help readers assess the size of the corrections.
Simulated Author's Rebuttal
We thank the referee for the positive report and the recommendation of minor revision. We appreciate the recognition of the significance of our results for NNLO calculations in the LEFT and the value of the public DsixTools implementation.
Circularity Check
No significant circularity; derivation uses external QCD inputs
full rationale
The paper states that it derives the two-loop ADM for four-fermion operators by feeding known UV poles from two-loop QCD diagrams into the LEFT basis (abstract and method description), together with an extension of a standard NDR γ5 prescription. No equations or steps reduce by construction to fitted parameters, self-definitions, or load-bearing self-citations whose validity depends on the present work. The public DsixTools implementation supplies an independent check. This is the normal non-circular case for a calculation paper that reuses established diagram results.
Axiom & Free-Parameter Ledger
axioms (2)
- standard math Standard QCD and QED Feynman rules together with NDR regularization using anticommuting γ5
- domain assumption Known results for UV poles in two-loop diagrams in QCD
Forward citations
Cited by 1 Pith paper
-
Next-to-next-to-leading QCD corrections to the $\mathbf{B^+}$-$\mathbf{B_d^0}$, $\mathbf{D^+}$-$\mathbf{D^0}$, and $\mathbf{D_s^+}$-$\mathbf{D^0}$ lifetime ratios
Three-loop perturbative corrections to B and D meson lifetime ratios are calculated, producing values that agree with experiment when using HQET sum rules or lattice inputs.
Reference graph
Works this paper leans on
-
[1]
Tentativo di una teoria dell’emissione dei raggi beta,
E. Fermi, “Tentativo di una teoria dell’emissione dei raggi beta,” Ric. Sci.4, 491-495 (1933)
work page 1933
-
[2]
Weak Decays Beyond Leading Logarithms
G. Buchalla, A. J. Buras and M. E. Lautenbacher, “Weak decays beyond leading logarithms,” Rev. Mod. Phys.68, 1125-1144 (1996) [arXiv:hep-ph/9512380 [hep-ph]]
work page internal anchor Pith review Pith/arXiv arXiv 1996
-
[3]
J. Aebischer, M. Fael, C. Greub and J. Virto, “B physics Beyond the Standard Model at One Loop: Complete Renormalization Group Evolution below the Electroweak Scale,” JHEP09, 158 (2017) [arXiv:1704.06639 [hep-ph]]
work page internal anchor Pith review Pith/arXiv arXiv 2017
-
[4]
Low-Energy Effective Field Theory below the Electroweak Scale: Operators and Matching,
E. E. Jenkins, A. V. Manohar and P. Stoffer, “Low-Energy Effective Field Theory below the Electroweak Scale: Operators and Matching,” JHEP03, 016 (2018) [erratum: JHEP12, 043 (2023)] [arXiv:1709.04486 [hep-ph]]
-
[5]
Effective Hamiltonian for Weak Radiative B Meson Decay,
B. Grinstein, R. P. Springer and M. B. Wise, “Effective Hamiltonian for Weak Radiative B Meson Decay,” Phys. Lett. B202, 138-144 (1988)
work page 1988
-
[6]
QCD corrected effective Lagrangian for b → s processes,
R. Grigjanis, P. J. O’Donnell, M. Sutherland and H. Navelet, “QCD corrected effective Lagrangian for b → s processes,” Phys. Lett. B213, 355 (1988) [erratum: Phys. Lett. B286, 413 (1992)]
work page 1988
-
[7]
QCD radiative corrections to B → Xse+e− processes,
R. Grigjanis, P. J. O’Donnell, M. Sutherland and H. Navelet, “QCD radiative corrections to B → Xse+e− processes,” Phys. Lett. B223, 239-244 (1989)
work page 1989
-
[8]
Strong Interaction Effects in Weak Radiative B Meson Decay,
B. Grinstein, R. P. Springer and M. B. Wise, “Strong Interaction Effects in Weak Radiative B Meson Decay,” Nucl. Phys. B339, 269-309 (1990)
work page 1990
-
[9]
QCD corrections to the weak radiative B meson decay,
G. Cella, G. Curci, G. Ricciardi and A. Vicere, “QCD corrections to the weak radiative B meson decay,” Phys. Lett. B248, 181-187 (1990)
work page 1990
-
[10]
QCD corrections to the¯B → Xse+e− decay,
G. Cella, G. Ricciardi and A. Vicere, “QCD corrections to the¯B → Xse+e− decay,” Phys. Lett. B 258, 212-218 (1991)
work page 1991
-
[11]
A. J. Buras and P. H. Weisz, “QCD Nonleading Corrections to Weak Decays in Dimensional Regularization and ’t Hooft-Veltman Schemes,” Nucl. Phys. B333, 66-99 (1990)
work page 1990
-
[12]
On the vanishing of evanescent operators,
M. J. Dugan and B. Grinstein, “On the vanishing of evanescent operators,” Phys. Lett. B 256, 239-244 (1991)
work page 1991
-
[13]
A. J. Buras, M. Jamin, M. E. Lautenbacher and P. H. Weisz, “Effective Hamiltonians for ∆S = 1 and ∆B = 1 nonleptonic decays beyond the leading logarithmic approximation,” Nucl. Phys. B370, 69-104 (1992)
work page 1992
-
[14]
A. J. Buras, M. Jamin, M. E. Lautenbacher and P. H. Weisz, “Two loop anomalous dimension matrix for∆S = 1 weak nonleptonic decays I:O(α2 s),” Nucl. Phys. B400, 37-74 (1993) [arXiv:hep-ph/9211304 [hep-ph]]
work page internal anchor Pith review Pith/arXiv arXiv 1993
-
[15]
A. J. Buras, M. Jamin and M. E. Lautenbacher, “Two loop anomalous dimension matrix for ∆S = 1 weak nonleptonic decays II:O(ααs),” Nucl. Phys. B400, 75-102 (1993) [arXiv:hep-ph/9211321 [hep-ph]]. – 54 –
work page internal anchor Pith review Pith/arXiv arXiv 1993
-
[16]
The $\Delta S=1$ Effective Hamiltonian Including Next-to-Leading Order QCD and QED Corrections
M. Ciuchini, E. Franco, G. Martinelli and L. Reina, “The∆S = 1 effective Hamiltonian including next-to-leading order QCD and QED corrections,” Nucl. Phys. B415, 403-462 (1994) [arXiv:hep-ph/9304257 [hep-ph]]
work page internal anchor Pith review Pith/arXiv arXiv 1994
-
[17]
M. Ciuchini, E. Franco, G. Martinelli, L. Reina and L. Silvestrini, “Scheme independence of the effective Hamiltonian forb → sγ and b → sg decays,” Phys. Lett. B316, 127-136 (1993) [arXiv:hep-ph/9307364 [hep-ph]]
work page internal anchor Pith review Pith/arXiv arXiv 1993
-
[18]
Two-loop mixing of dimension-five flavor-changing operators
M. Misiak and M. Munz, “Two loop mixing of dimension five flavor changing operators,” Phys. Lett. B344, 308-318 (1995) [arXiv:hep-ph/9409454 [hep-ph]]
work page internal anchor Pith review Pith/arXiv arXiv 1995
-
[19]
Evanescent Operators, Scheme Dependences and Double Insertions
S. Herrlich and U. Nierste, “Evanescent operators, scheme dependences and double insertions,” Nucl. Phys. B455, 39-58 (1995) [arXiv:hep-ph/9412375 [hep-ph]]
work page internal anchor Pith review Pith/arXiv arXiv 1995
-
[20]
Weak Radiative B-Meson Decay Beyond Leading Logarithms
K. G. Chetyrkin, M. Misiak and M. Munz, “Weak radiative B meson decay beyond leading logarithms,” Phys. Lett. B400, 206-219 (1997) [erratum: Phys. Lett. B425, 414 (1998)] [arXiv:hep-ph/9612313 [hep-ph]]
work page internal anchor Pith review Pith/arXiv arXiv 1997
-
[21]
|Delta F| = 1 Nonleptonic Effective Hamiltonian in a Simpler Scheme
K. G. Chetyrkin, M. Misiak and M. Munz, “|∆F | = 1 nonleptonic effective Hamiltonian in a simpler scheme,” Nucl. Phys. B520, 279-297 (1998) [arXiv:hep-ph/9711280 [hep-ph]]
work page internal anchor Pith review Pith/arXiv arXiv 1998
-
[22]
Photonic penguins at two loops and m_t-dependence of BR[ B -> X_s l^+ l^-]
C. Bobeth, M. Misiak and J. Urban, “Photonic penguins at two loops andmt dependence of BR[B → Xsl+l−],” Nucl. Phys. B574, 291-330 (2000) [arXiv:hep-ph/9910220 [hep-ph]]
work page internal anchor Pith review Pith/arXiv arXiv 2000
-
[23]
A. J. Buras, M. Misiak and J. Urban, “Two loop QCD anomalous dimensions of flavor changing four quark operators within and beyond the standard model,” Nucl. Phys. B586, 397-426 (2000) [arXiv:hep-ph/0005183 [hep-ph]]
-
[24]
Anomalous Dimension Matrix for Radiative and Rare Semileptonic B Decays up to Three Loops
P. Gambino, M. Gorbahn and U. Haisch, “Anomalous dimension matrix for radiative and rare semileptonic B decays up to three loops,” Nucl. Phys. B673, 238-262 (2003) [arXiv:hep-ph/0306079 [hep-ph]]
work page internal anchor Pith review Pith/arXiv arXiv 2003
-
[25]
Complete NNLO QCD Analysis of B -> X_s l^+ l^- and Higher Order Electroweak Effects
C. Bobeth, P. Gambino, M. Gorbahn and U. Haisch, “Complete NNLO QCD Analysis of ¯B → Xs ℓ+ℓ− and Higher Order Electroweak Effects,” JHEP04, 071 (2004) [arXiv:hep-ph/0312090 [hep-ph]]
work page internal anchor Pith review Pith/arXiv arXiv 2004
-
[26]
Effective Hamiltonian for Non-Leptonic |Delta F| = 1 Decays at NNLO in QCD
M. Gorbahn and U. Haisch, “Effective Hamiltonian for non-leptonic|∆F | = 1 decays at NNLO in QCD,” Nucl. Phys. B713, 291-332 (2005) [arXiv:hep-ph/0411071 [hep-ph]]
work page internal anchor Pith review Pith/arXiv arXiv 2005
-
[27]
Electromagnetic Logarithms in B -> X_s l+ l-
T. Huber, E. Lunghi, M. Misiak and D. Wyler, “Electromagnetic logarithms in ¯B → Xsl+l−,” Nucl. Phys. B740, 105-137 (2006) [arXiv:hep-ph/0512066 [hep-ph]]
work page internal anchor Pith review Pith/arXiv arXiv 2006
-
[28]
Electroweak Corrections to $B_{s,d} \to \ell^+ \ell^-$
C. Bobeth, M. Gorbahn and E. Stamou, “Electroweak Corrections toBs,d → ℓ+ℓ−,” Phys. Rev. D 89, no.3, 034023 (2014) [arXiv:1311.1348 [hep-ph]]
work page internal anchor Pith review Pith/arXiv arXiv 2014
-
[29]
Computing Tools for the SMEFT,
J. Aebischer, M. Fael, A. Lenz, M. Spannowsky, J. Virto, I. Brivio, J. C. Criado, A. Dedes, J. Kumar and M. Misiak,et al. “Computing Tools for the SMEFT,” [arXiv:1910.11003 [hep-ph]]
-
[30]
J. Aebischer, M. Fael, J. Fuentes-Martín, A. E. Thomsen, J. Virto, L. Allwicher, S. Das Bakshi, H. Bélusca-Maïto, J. de Blas and M. Chala,et al. “Computing tools for effective field – 55 – theories: SMEFT-Tools 2022 Workshop Report, 14–16th September 2022, Zürich,” Eur. Phys. J. C84, no.2, 170 (2024) [arXiv:2307.08745 [hep-ph]]
-
[31]
Low-Energy Effective Field Theory below the Electroweak Scale: Dimension-8 Operators,
C. W. Murphy, “Low-Energy Effective Field Theory below the Electroweak Scale: Dimension-8 Operators,” JHEP04, 101 (2021) [arXiv:2012.13291 [hep-ph]]
-
[32]
Dimension-8 SMEFT matching conditions for the low-energy effective field theory,
S. Hamoudou, J. Kumar and D. London, “Dimension-8 SMEFT matching conditions for the low-energy effective field theory,” JHEP03, 157 (2023) [arXiv:2207.08856 [hep-ph]]
-
[33]
Low-Energy Effective Field Theory below the Electroweak Scale: Anomalous Dimensions,
E. E. Jenkins, A. V. Manohar and P. Stoffer, “Low-Energy Effective Field Theory below the Electroweak Scale: Anomalous Dimensions,” JHEP01, 084 (2018) [erratum: JHEP12, 042 (2023)] [arXiv:1711.05270 [hep-ph]]
-
[34]
Low-energy effective field theory below the electroweak scale: matching at one loop,
W. Dekens and P. Stoffer, “Low-energy effective field theory below the electroweak scale: matching at one loop,” JHEP10, 197 (2019) [erratum: JHEP11, 148 (2022)] [arXiv:1908.05295 [hep-ph]]
-
[35]
On the two-loop penguin contributions to the Anomalous Dimensions of four-quark operators,
P. Morell and J. Virto, “On the two-loop penguin contributions to the Anomalous Dimensions of four-quark operators,” JHEP04, 105 (2024) [arXiv:2402.00249 [hep-ph]]
-
[36]
L. Naterop and P. Stoffer, “Low-energy effective field theory below the electroweak scale: one-loop renormalization in the ’t Hooft-Veltman scheme,” JHEP02, 068 (2024) [arXiv:2310.13051 [hep-ph]]
-
[37]
Renormalization-group equations of the LEFT at two loops: dimension-five effects,
L. Naterop and P. Stoffer, “Renormalization-group equations of the LEFT at two loops: dimension-five effects,” [arXiv:2412.13251 [hep-ph]]
-
[38]
One-loop Fierz transformations,
J. Aebischer and M. Pesut, “One-loop Fierz transformations,” JHEP10, 090 (2022) [arXiv:2208.10513 [hep-ph]]
-
[39]
Dipole operators in Fierz identities,
J. Aebischer, M. Pesut and Z. Polonsky, “Dipole operators in Fierz identities,” Phys. Lett. B 842, 137968 (2023) [arXiv:2211.01379 [hep-ph]]
-
[40]
Renormalization scheme factorization of one-loop Fierz identities,
J. Aebischer, M. Pesut and Z. Polonsky, “Renormalization scheme factorization of one-loop Fierz identities,” JHEP01, 060 (2024) [arXiv:2306.16449 [hep-ph]]
-
[41]
A simple dirac prescription for two-loop anomalous dimension matrices,
J. Aebischer, M. Pesut and Z. Polonsky, “A simple dirac prescription for two-loop anomalous dimension matrices,” Eur. Phys. J. C84, no.7, 750 (2024) [arXiv:2401.16904 [hep-ph]]
-
[42]
WCxf: an exchange format for Wilson coefficients beyond the Standard Model
J. Aebischer, I. Brivio, A. Celis, J. A. Evans, Y. Jiang, J. Kumar, X. Pan, W. Porod, J. Rosiek and D. Shih,et al. “WCxf: an exchange format for Wilson coefficients beyond the Standard Model,” Comput. Phys. Commun.232, 71-83 (2018) [arXiv:1712.05298 [hep-ph]]
work page internal anchor Pith review Pith/arXiv arXiv 2018
-
[43]
DsixTools: The Standard Model Effective Field Theory Toolkit
A. Celis, J. Fuentes-Martin, A. Vicente and J. Virto, “DsixTools: The Standard Model Effective Field Theory Toolkit,” Eur. Phys. J. C77, no.6, 405 (2017) [arXiv:1704.04504 [hep-ph]]
work page internal anchor Pith review Pith/arXiv arXiv 2017
-
[44]
DsixTools 2.0: The Effective Field Theory Toolkit,
J. Fuentes-Martin, P. Ruiz-Femenia, A. Vicente and J. Virto, “DsixTools 2.0: The Effective Field Theory Toolkit,” Eur. Phys. J. C81, no.2, 167 (2021) [arXiv:2010.16341 [hep-ph]]
-
[45]
J. Aebischer, J. Kumar and D. M. Straub, “Wilson: a Python package for the running and matching of Wilson coefficients above and below the electroweak scale,” Eur. Phys. J. C78, no.12, 1026 (2018) [arXiv:1804.05033 [hep-ph]]. – 56 –
work page internal anchor Pith review Pith/arXiv arXiv 2018
-
[46]
wilson: A package for renormalization group running in the SMEFT with Sterile Neutrinos,
J. Aebischer, T. Kapoor and J. Kumar, “wilson: A package for renormalization group running in the SMEFT with Sterile Neutrinos,” [arXiv:2411.07220 [hep-ph]]
-
[47]
S. Di Noi and L. Silvestrini, “RGESolver: a C++ library to perform renormalization group evolution in the Standard Model Effective Theory,” Eur. Phys. J. C83, no.3, 200 (2023) [arXiv:2210.06838 [hep-ph]]
-
[48]
A Global Likelihood for Precision Constraints and Flavour Anomalies
J. Aebischer, J. Kumar, P. Stangl and D. M. Straub, “A Global Likelihood for Precision Constraints and Flavour Anomalies,” Eur. Phys. J. C79, no.6, 509 (2019) [arXiv:1810.07698 [hep-ph]]
work page internal anchor Pith review Pith/arXiv arXiv 2019
-
[49]
Two Loop Calculations in QCD and the∆I = 1/2 Rule in Nonleptonic Weak Decays,
N. Tracas and N. Vlachos, “Two Loop Calculations in QCD and the∆I = 1/2 Rule in Nonleptonic Weak Decays,” Phys. Lett. B115, 419 (1982)
work page 1982
-
[50]
General non-leptonic∆F = 1 WET at the NLO in QCD,
J. Aebischer, C. Bobeth, A. J. Buras, J. Kumar and M. Misiak, “General non-leptonic∆F = 1 WET at the NLO in QCD,” JHEP11, 227 (2021) [arXiv:2107.10262 [hep-ph]]
-
[51]
Simple rules for evanescent operators in one-loop basis transformations,
J. Aebischer, A. J. Buras and J. Kumar, “Simple rules for evanescent operators in one-loop basis transformations,” Phys. Rev. D107, no.7, 075007 (2023) [arXiv:2202.01225 [hep-ph]]. – 57 –
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.