REVIEW
Master Formulae for Delta F=2 NLO-QCD Factors in the Standard Model and Beyond
High Energy Physics - Phenomenology · Submitted 26 Feb 2001 · 15 references
Pith's verdict: A solid standard-reference paper: complete analytic NLO ΔF=2 evolution matrices in NDR, with one flagged convention in the ρ-sector that deserves a caution but not alarm.
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Referee report
The paper
The paper claims
The paper supplies closed-form next-to-leading-order QCD evolution matrices for all $Delta F=2$ four-quark operators, so that one universal set of factors carries any model's short-distance Wilson coefficients at the top-mass scale down to,
The reading
What carries the argument
The load-bearing object is the evolution matrix written as $hat U(mu_1,mu_2) = (1 + frac{alpha_s(mu_1)}{4pi}hat J) hat U^{(0)} (1 - frac{alpha_s(mu_2)}{4pi}hat J)$ with the leading-order solution $hat U^{(0)} = (alpha_s(mu_2)/alpha_s(mu_1))^{hatgamma^{(0)T}/(2beta_0)}$, built from the one-loop anomalous dimension matrix and the two-loop matrix of the NDR calculation, plus the $hat J$ matrix constructed from the two-loop anomalous dimensions and the $\beta$ function. Because the operators do not mix across chirality sectors, the problem splits into a scalar VLL entry and $2times 2$ matrices for LR and SLL, and crossing quark thresholds is handled by a product of such factors in the $f=5$, $f=4$ and $f=3$ effective theories, with the convention that powers and logarithms of the coupling ratios count as $O(alpha_s^0)$ so that all $O(alpha_s^2)$ terms are consistently dropped. The $rho$ matrices are the same construction run in the opposite direction, from 2 GeV down to $mu_K$, and the scheme-conversion matrices $Delta hat r$ let the results be translated to other renormalization schemes.
Extended reading notes
Core claim
The central claim is that the next-to-leading-order evolution matrices $hat U(mu, mu_t)$ and $hat U(mu_K, mu_L)$ for the $Delta F=2$ dimension-six four-quark operators can be given in explicit closed form in the NDR scheme, for the VLL, LR and SLL sectors (VRR and SRR follow by chirality), with no numerical integration required. Sections 3 and 4 present these as algebraic expressions in the coupling ratios $eta_3$, $eta_4$, $eta_5$ and $tildeeta_4$, separating a leading-order power $eta^P$ from an $O(alpha_s)$ correction; Sections 5 and 6 give numerical tables, the scheme-conversion rules to other renormalization schemes, and the relation to the older $eta_B$ and $eta_2$ factors. The authors report that the running is mild in the vector-vector sector but large in the left-right and scalar sectors: at $mu_K = 1$ GeV the diagonal entry $[eta_{22}]^{LR}$ is enhanced by about a factor of 5.6, $[eta_{11}]^{SLL}$ by about 2.9, while $[eta_{22}]^{SLL}$ is suppressed to about 0.26, and the NLO corrections are typically 5 to 15 percent, reaching about 25 percent for $[eta_{21}]^{LR}$, $[eta_{22}]^{LR}$ and $[eta_{22}]^{SLL}$. Section 7 turns this into master formulae for $Delta M_K$, $Delta M_B$ and $epsilon_K$ in terms of non-perturbative $B_i$ parameters and the Wilson coefficients at $mu_t$, with universal coefficients $P^{VLL}_1 = 0.48$, $P^{LR}_1 = -36.1$, $P^{LR}_2 = 59.3$, $P^{SLL}_1 = -18.1$, $P^{SLL}_2 = -32.2$ in the kaon system.
Load-bearing premise
The left-right $rho$ coefficient in eq. (4.10) contains a term proportional to $log(eta_3)$ that arises only by taking the limit $f to 3$ of the general evolution formula, because the matrix $hat J$ is singular there; the authors classify that limit term as a next-to-leading contribution under their convention, and if that bookkeeping is not the right way to organize the expansion the LR entry of the kaon master formula is mis-assigned.
Editorial extensions
If this is right
- Once a model's Wilson coefficients $C_i(mu_t)$ are computed in the NDR scheme, $Delta M_K$, $Delta M_B$ and $epsilon_K$ follow directly from the universal $P^a_i$ coefficients, with no further QCD work by the user.
- In the kaon system the left-right and scalar coefficients are two orders of magnitude larger than the vector-vector one ($P^{LR}_1 = -36.1$, $P^{LR}_2 = 59.3$, $P^{SLL}_1 = -18.1$, $P^{SLL}_2 = -32.2$ against $P^{VLL}_1 = 0.48$), so even small new-physics contributions to those operators can dominate the mixing amplitude.
- Lattice matrix elements quoted at 2 GeV and hadronic-model matrix elements computed below 1 GeV can be placed on a common scale and compared directly.
- The familiar Standard Model factors $eta_B$ and $eta_2$ are not the same objects as $[eta(mu_b)]^{VLL}$ and $[eta(mu_K)]^{VLL}$; the paper supplies the explicit conversion between them.
- The paper also provides the evolution matrix for running upward from $mu_t$ to a higher new-physics scale $mu_s$ in a six-flavour effective theory, so that models with very heavy particles can be matched in stages.
Reading between the lines
- Because the $P^a_i$ are universal numbers, they can be reused as a fixed lookup table by any future model builder; the practical bottleneck then shifts entirely to computing $C_i(mu_t)$ and to the lattice $B$ parameters in the LR and SLL sectors, which Section 7 shows are the least controlled, with scheme shifts of roughly 30 and 20 percent respectively.
- The size of the LR and SLL enhancements suggests that meson-mixing observables are far more sensitive to chirality-flipped operators than to the standard vector-vector one, which is an argument that a future discrepancy in $epsilon_K$ or $Delta M_K$ would more plausibly point to scalar or left-right new physics than to a shift in the standard operator.
- The treatment of the $f=3$ limit in the LR sector implies that 'next-to-leading order' in a multi-threshold evolution is partly a bookkeeping convention; two groups using different conventions could legitimately differ at the few-percent level the introduction warns about, without either being wrong.
- A useful cross-check that the paper does not perform would be to evolve a set of lattice matrix elements from 2 GeV down to 1 GeV and back with the $rho$ matrices and verify closure at the stated accuracy; a failure of closure would localize the problem to a specific sector.
Original abstract
We present analytic formulae for the QCD renormalization group factors relating the Wilson coefficients C_i(mu_t) and C_i(mu), with mu_t = O(m_t) and mu < mu_t, of the Delta F=2 dimension six four-quark operators Q_i in the Standard Model and in all of its extensions. Analogous analytic formulae for the QCD factors relating the matrix elements <Q_i(2 GeV)> and <Q_i(mu_K)> with mu_K < 2GeV are also presented. The formulae are given in the NDR scheme. The strongest renormalization-group effects are found for the operators with the Dirac structures (1 - gamma_5)*(1 + gamma_5) and (1 - gamma_5)*(1 - gamma_5). We calculate the matrix elements <\bar K^0|Q_i|K^0> in the NDR scheme using the lattice results in the LRI scheme. We give expressions for the mass differences Delta M_K and Delta M_B and the CP-violating parameter epsilon_K in terms of the non-perturbative parameters B_i and the Wilson coefficients C_i(mu_t). The latter summarize the dependence on new physics contributions.
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 present analytic formulae for the QCD renormalization group factors relating the Wilson coefficients C_i(mu_t) and C_i(mu), with mu_t = O(m_t) and mu < mu_t, of the Delta F=2 dimension six four-quark operators Q_i in the Standard Model and in all of its extensions. Analogous analytic formulae for the QCD factors relating the matrix elements <Q_i(2 GeV)> and <Q_i(mu_K)> with mu_K < 2GeV are also presented. The formulae are given in the NDR scheme. The strongest renormalization-group effects are found for the operators with the Dirac structures (1 - gamma_5)*(1 + gamma_5) and (1 - gamma_5)*(1 - gamma_5). We calculate the matrix elements <\bar K^0|Q_i|K^0> in the NDR scheme using the lattice results in the LRI scheme. We give expressions for the mass differences Delta M_K and Delta M_B and the CP-violating parameter epsilon_K in terms of the non-perturbative parameters B_i and the Wilson coefficients C_i(mu_t). The latter summarize the dependence on new physics contributions.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | We present analytic formulae for the QCD renormalization group factors relating the Wilson coefficients C_i(mu_t) and C_i(mu), with mu_t = O(m_t) and mu < mu_t, of the Delta F=2 dimension six four-quark operators Q_i in the Standard Model and in all of its extensions. | contribution 1.00 | 0.95 | 0.62 | asserted 1.00 |
| s1 | Analogous analytic formulae for the QCD factors relating the matrix elements <Q_i(2 GeV)> and <Q_i(mu_K)> with mu_K < 2GeV are also presented. | contribution 0.96 | 0.92 | 0.10 | asserted 1.00 |
| s2 | The formulae are given in the NDR scheme. | method 0.89 | 0.65 | 0.05 | asserted 1.00 |
| s3 | The strongest renormalization-group effects are found for the operators with the Dirac structures (1 - gamma_5)*(1 + gamma_5) and (1 - gamma_5)*(1 - gamma_5). | result 0.98 | 0.87 | 0.13 | asserted 1.00 |
| s4 | We calculate the matrix elements <\bar K^0|Q_i|K^0> in the NDR scheme using the lattice results in the LRI scheme. | method 0.86 | 0.93 | 0.05 | asserted 1.00 |
| s5 | We give expressions for the mass differences Delta M_K and Delta M_B and the CP-violating parameter epsilon_K in terms of the non-perturbative parameters B_i and the Wilson coefficients C_i(mu_t). | contribution 0.65 | 0.89 | 0.22 | asserted 1.00 |
| s6 | The latter summarize the dependence on new physics contributions. | interpretation 0.96 | 0.55 | 0.10 | asserted 0.99 |
What was examined, and what was not
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Figures
Figures reproduced from arXiv:hep-ph/0102316 by the authors.
References
How later papers used it
88 later papers cite it
6 later papers by other authors are listed below: 5 used its method or tool and 1 used its data or values. 3 more papers by the same authors are listed: 1 built on it, 1 used its method or tool and 1 used its data or values.
Builds on it 1 of 2 papers with this label · 1 by the same authors
By the same authors
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Presented an update of the master formula for Delta F=2 processes in LEFT valid in any BSM scenario first presented in this paper.
SMEFT ATLAS of $\Delta F=2$ Transitions (2020) (same authors) · 0.86 · paraphrased: the licence does not allow quoting
Uses its method or tool 6 of 31 papers with this label · 1 by the same authors
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Used Eqs. (7.24)-(7.27) of this paper for the Delta B=2 and Delta S=2 amplitudes to compute the observables in terms of Wilson coefficients of dimension-six operators.
Exploring the flavour structure of the high-scale MSSM (2019) · 1.00 · paraphrased: the licence does not allow quoting
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Performed the running for O_1^SRR using the results of this paper.
Charged-Higgs phenomenology in the Aligned two-Higgs-doublet model (2010) · 0.90 · paraphrased: the licence does not allow quoting
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Followed this paper to perform renormalization group evolution of the NP operators O_1^SLL, O_1^SRR and O_2^LR.
Flavor Violating Higgs Couplings in Minimal Flavor Violation (2018) · 1.00 · paraphrased: the licence does not allow quoting
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Used the notation of Eq. (2.1) in this paper and expressed the Wilson coefficient of the operator Q_1 s^LR by performing a Fierz transformation to the operator Q_5 in the SUSY basis.
Revisiting R-parity violating interactions as an explanation of the B-physics anomalies (2018) · 0.88 · paraphrased: the licence does not allow quoting
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Gave results in the continuum MS-NDR scheme at scale m_b using both the BBGLN and BJU choices of evanescent operators.
Neutral $B$ mixing from 2+1 flavor lattice-QCD: the Standard Model and beyond (2011) · 0.92 · paraphrased: the licence does not allow quoting
By the same authors
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Obtained the values of the Wilson coefficients at scales O(mu_B) by the standard techniques of this paper.
EDMs vs. CPV in B_{s,d} mixing in two Higgs doublet models with MFV (2010) (same authors) · 0.91 · paraphrased: the licence does not allow quoting
Uses its data or values 2 of 19 papers with this label · 1 by the same authors
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Employed the formulas provided by this paper, using eta_LL=0.65, eta_LR=0.99 and eta_LR'=-5.08 at the scale mu=1 GeV.
$\Delta S=2$ nonleptonic hyperon decays as probes of new physics (2023) · 0.83 · paraphrased: the licence does not allow quoting
By the same authors
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Used by default the B_i^X values at the scale mu=2 GeV given in this paper using the NDR renormalization scheme.
SUSY_FLAVOR: a computational tool for FCNC and CP-violating processes in the MSSM (2010) (same authors) · 1.00 · paraphrased: the licence does not allow quoting
How the literature uses it
85 arXiv papers cite this in 159 sentences
Papers citing it · 91 sentences without a confident label
Builds on it 2 papers
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In sec:LEFT-master we present an update of the master formula for $=2$ processes ($$, $$ and $$) in LEFT valid in any BSM scenario first presented in [ref] .
SMEFT ATLAS of $\Delta F=2$ Transitions · Introduction · 0.86
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We quote all three matrices here, so that the formulae of Ref. [ref] can be easily extended to the $(Q_1^SLL,Q_1^SLL)$ basis: [equation]
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Uses its method or tool 31 papers
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To compute explicitly the $ΔO_i^NP(x)$ we use the expressions of the observables in terms Wilson Coefficients of dimension-six operators according to the following references: * $ΔB = 2$ and $ΔS=2$ amplitudes: Eqs. (7.24)–(7.27) in Ref. [ref] ; * $ΔC = 2$ amplitude: Eq. (3) in Ref. [ref] ; * $ϵ_K'/ϵ_K$: Eq. (82) in Ref. [ref] , * $ℬ (B→X_sγ)$: Eq. (33) in Ref. [ref] ; * $ℬ (K^+ →π^+ ν̅ ν)$: Eq. (24) in Ref. [ref] [We have contacted the authors and confirmed that the parameter $κ$ should be rescaled by a factor of $(2^3/2 πsin^2θ_W v/α)^2$.].
Exploring the flavour structure of the high-scale MSSM · Analysis strategy · 1.00
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The Wilson coefficients are evolved to the low scale $μ_low$ by solving their renormalization group equations [ref] .
A Supersymmetric Flavor Clockwork · Constraints from Meson Mixing · 0.98
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[ref] to perform renormalization group evolution of the NP operators $𝒪_1^SLL$, $𝒪_1^SRR$ and $𝒪_2^LR$.
Flavor Violating Higgs Couplings in Minimal Flavor Violation · Neutral $B$ and $K$ meson mixing · 1.00
Uses its data or values 19 papers
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Thus, with $ΔM_d^exp=(0.507±0.005) ps^-1$ [ref] and $ΔM_d^SM=(0.560^+0.067_-0.076) ps^-1$ [ref] , using the approximation $|1+δ_d^|≃1+Re δ_d$, we can extract the $1 σ$ range [equation] Similarly, $ΔM_s^exp=(17.77±0.12) ps^-1$ [ref] and $ΔM_s^SM=(17.6^+1.7_-1.8) ps^-1$ [ref] translate into [equation] To proceed, in addition to $m_X^=214.3$ MeV, we use $m_b^=4.4$ GeV, $P_1^VLL=0.84$, $P_1^SLL=-1.47$, $P_1^LR=-1.62$, $P_2^LR=2.46$ [ref] , CKM parameters from Ref. [ref] , $f_B_d=190$ MeV, $f_B_s=228$ MeV, $η_B^=0.551$, $B_B_d=1.17$, and $B_B_s=1.23$ [ref] , as well as meson masses from Ref. [ref] .
Rare B Decays with a HyperCP Particle of Spin One · Constraints from $B_q$-$B̅_q$ mixing · 0.99
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In performing the NLO QCD evolutions we have used the $P_a^ij()$ from [ref] , see [ref], which are based on the two-loop anomalous dimensions of operators calculated in [ref] .
SMEFT ATLAS of $\Delta F=2$ Transitions · The Issue of Evanescent Operators · 0.83
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The bag parameters at the $μ_b = m_b$ scale are given as [ref] [equation] and the QCD corrections are $η_11 (μ_b)=1.654$ and $η_21 (μ_b)=-0.007$ [ref] .
Flavor constraints on the Two Higgs Doublet Models of $Z_2$ symmetric and aligned types · Input and experimental data · 1.00
Compares with it 1 paper
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The result is [equation] The number in p2lrnum is significantly larger than $P_2^LR=2.46$ quoted in Ref. [ref] , because our value for $m_b$ is smaller and the lattice bag factors are larger than one.
The supersymmetric Higgs sector and B-Bbar mixing for large tan beta · Hadronic matrix elements and heavy-quark relations · 0.83
Cites it as background 5 papers
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The strength of $B_s(d)-B̅_s(d)$ mixing is described by the mass difference $ΔM_s(d)$, defined by [ref] [equation] where $M_12^q$ denotes the off-diagonal element in the neutral $B_q$-meson mass matrix, and the effective weak Hamiltonian can be written in a general form as [ref] [equation] Within the $ℤ_3$-invariant NMSSM with NMFV, the following eight operators, as defined in Ref. [ref] , are all found to be relevant: [equation] where $α$ and $β$ are the colour indices, $σ_μν=1/2[γ_μ,γ_ν]$, and $P_L,R=(1∓γ_5)/2$.
$B_{s(d)}-\bar{B}_{s(d)}$ Mixing and $B_s\to\mu^+\mu^-$ Decay in the NMSSM with the Flavour Expansion Theorem · $B_s(d)-B̅_s(d)$ mixing · 0.83
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There are in principle eight dimension-six four-quark operators that can contribute to down-type $ΔF=2$ processes [ref] .
Solving the flavour problem with hierarchical fermion wave functions · $ΔF=2$ operators · 0.92
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The detailed formulae for $K_0-K̅_0$ mixing can be found in reference [ref] .
Flavour-alignment in an $S_3$-symmetric Higgs sector and its RG-behaviour · $K_0-K̅_0$ mixing · 0.91
Discussion
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