REVIEW
Gauge Dependence of the High-Temperature 2-Loop Effective Potential for the Higgs Field
High Energy Physics - Phenomenology · Submitted 9 Nov 1994 · 17 references
Pith's verdict: A careful, honest two-loop check of gauge independence whose durable product is the appendix formula, with one compressed algebraic step in the middle.
T0 · AI review
Why Pith says this
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Referee report
The paper
The paper claims
The pressure at the broken Higgs minimum is gauge-independent through two loops.
The reading
What carries the argument
The load-bearing device is the order-by-order shift of the minimum in the loop expansion. Writing $V=V_0+hbar V_1+hbar^2 V_2$ and $phi_{min}=phi_0+hbarphi_1+hbar^2phi_2$, the value at the minimum is $V_0+hbar V_1+hbar^2[V_2-tfrac12 (V_1')^2/V_0'']$ evaluated at $phi_0$, with terms proportional to $V_0'$ dropped. The term $-tfrac12 (V_1')^2/V_0''$ is what cancels the finite gauge-dependent part of $V_2$ and the Goldstone infrared divergence. The calculation uses the decomposition of the gauge-dependent Goldstone propagator into two Landau-gauge-like poles with $R_pm^2=1/2pmsqrt{1/4-xi(m_T/m_2)^2}$, reducing the two-loop integrals to standard Landau-gauge values. The appendix gives the complete two-loop potential, which is the concrete object other workers can check.
Extended reading notes
Core claim
The central claim is that the pressure of electroweak matter at high temperature can be extracted gauge-independently from the conventional gauge-dependent effective potential $V(phi)$ at order $hbar^2$. Working in the effective 3d SU(2)-Higgs theory with an $A_0$ field and a general covariant gauge, the author computes all non-vanishing two-loop vacuum diagrams and shows that the would-be gauge-dependent pieces cancel in $V(phi_{min})$. The cancellation involves both the explicit $xi$-dependent terms in the two-loop potential and the displacement of the minimum from its classical location; the latter contributes $-(V_1')^2/(2V_0'')$, which cancels the finite gauge-dependent remainder of $V_2$ and the infrared-divergent piece as $m_2^2to0$. The same value follows from the gauge-independent generating functional with source $2JPhi^daggerPhi$, so the two definitions agree for the equation of state at this order. The author is explicit that this does not make the phase transition's critical temperature or latent heat calculable to $hbar^2$.
Load-bearing premise
The argument rests on regulating the Goldstone infrared divergence by taking $m_2^2to0^+$ and dropping the correction terms proportional to $V_0'$; if that limiting procedure does not faithfully represent an expansion about the true minimum, the claimed gauge cancellation at order $hbar^2$ is not established.
Editorial extensions
If this is right
- If the claim holds, the standard gauge-dependent effective potential can be used for the high-temperature equation of state at two loops without introducing a gauge artifact at that order.
- The gauge-independent composite-source effective potential and the conventional effective potential agree for the pressure at order $hbar^2$, providing a consistency check between two formalisms.
- The difference between the symmetric and broken phase pressures, and hence the critical temperature and latent heat, is gauge- and scale-independent at order $hbar^2$, although the paper argues these quantities are not reliably computable because of infrared problems.
- Deep in the broken phase, away from the critical temperature, renormalization-group-improved perturbation theory appears convergent, and the size of gauge dependence can serve as an estimate of missing higher-order terms.
- The explicit two-loop expression in the appendix allows independent checks and extension to other gauges, models, or observables.
Reading between the lines
- The cancellation mechanism suggests that gauge dependence of the effective potential is not only an obstacle but also a diagnostic: its size can estimate the error from truncated higher-order terms, as the paper does in the broken phase.
- The failure to compute the critical temperature and latent heat at order $hbar^2$ is a symptom of the known infrared problem of high-temperature field theory; dimensional reduction to three dimensions does not by itself cure the Goldstone mode near the transition.
- The distinction between gauge dependence at the minimum and away from it may generalize to other composite-source effective potentials; the equality of pressures could be tested at three loops or nonperturbatively.
- If the limiting procedure for the Goldstone infrared divergence is subtle, a lattice calculation of the pressure in the broken phase could test the two-loop gauge-independence claim independently.
Original abstract
The high-temperature limit of the 2-loop effective potential for the Higgs field is calculated from an effective 3d theory, in a general covariant gauge. It is shown explicitly that a gauge-independent result can be extracted for the equation of state from the gauge-dependent effective potential. The convergence of perturbation theory is estimated in the broken phase, utilizing the gauge dependence of the effective potential.
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
The high-temperature limit of the 2-loop effective potential for the Higgs field is calculated from an effective 3d theory, in a general covariant gauge. It is shown explicitly that a gauge-independent result can be extracted for the equation of state from the gauge-dependent effective potential. The convergence of perturbation theory is estimated in the broken phase, utilizing the gauge dependence of the effective potential.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | The high-temperature limit of the 2-loop effective potential for the Higgs field is calculated from an effective 3d theory, in a general covariant gauge. | method 0.67 | 0.92 | 0.06 | asserted 1.00 |
| s1 | It is shown explicitly that a gauge-independent result can be extracted for the equation of state from the gauge-dependent effective potential. | result 0.99 | 0.92 | 0.72 | asserted 1.00 |
| s2 | The convergence of perturbation theory is estimated in the broken phase, utilizing the gauge dependence of the effective potential. | contribution 0.52 | 0.88 | 0.12 | asserted 0.91 |
What was examined, and what was not
- arXiv listing abstract v2
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- P abstract
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Figures
Figures reproduced from arXiv:hep-ph/9411252 by the authors.
References
How the literature uses it
36 arXiv papers cite this in 98 sentences
Papers citing it · 69 sentences without a confident label
Contests it 2 papers
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The next two orders in the expansion are [ We remind the reader that prime is used to denote the temperature derivative, $V_0' ≡d V_0/dT$. ] [equation] Similarly, expanding the latent heat [equation] where [equation] We emphasize that in consistent EFT expansions we do not encounter the problem reported in [ref] , whereby the condition $Δp_0(T_0) = 0$ leads to a vanishing mass parameter $μ^2_3(T_0) = 0$ which then results in spurious IR divergences at two-loop order for $T_2$.
Perturbative effective field theory expansions for cosmological phase transitions · Strict perturbative expansions · contest 0.73
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Thus, it appears to us that the breakdown of the $ħ$ expansion as obtained in Ref. [ref] is a consequence of expanding $T_C$ itself.
Baryon Washout, Electroweak Phase Transition, and Perturbation Theory · High-$T$ effective theory · contest 0.79
Builds on it 1 paper
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Expanding the potential and its minima as [equation] and generalizing the analysis of [ref] to the case of two background fields gives the $ħ$ expansion" [equation] All derivatives are to be evaluated at the tree-level minimum $(v_0, x_0)$.
Thermodynamics of a two-step electroweak phase transition · Gauge-invariant effective potential to two loops · 0.95
Uses its method or tool 5 papers
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When determining the critical temperature ($$) and other thermodynamic quantities of interest, we resort to a technique described in [ref] rather than expanding $$ explicitly in $ħ$ as in [ref] .
Combining thermal resummation and gauge invariance for electroweak phase transition · Introduction · 0.92
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Evolution of the different minima is tracked using the gauge-invariant approach described in [ref] ; details of the calculation can be found in the Appendix.
Thermodynamics of a two-step electroweak phase transition · Effective theory at high temperature · 1.00
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The extremal conditions [equation] can be solved either with a numerical minimization algorithm, or perturbatively by expanding around leading order minima [ref] (sometimes called the “$ħ$ expansion”).
Investigating two-loop effects for first-order electroweak phase transitions · Thermal effective potential · 0.98
Compares with it 1 paper
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Inclusion of the $𝒪(ħ)$ terms yields a contribution $T_1$ proportional to the product[In the notation of [ref] these are denoted $h_3$ and $m_D$, respectively.] of $H^ab_ij$ and $Π^ab(T)$.
Baryon Washout, Electroweak Phase Transition, and Perturbation Theory · High-$T$ effective theory · 0.86
Cites it as support 6 papers
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Notably, this expansion is gauge invariant order by order [ref] , since it satisfies the Nielsen-Fukuda-Kugo identities within the EFT [ref] , and the construction of the EFT through dimensional reduction is gauge invariant [ref] .
Perturbative effective field theory expansions for cosmological phase transitions · Strict perturbative expansions · 0.98
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This would lead to an IR divergence for the singlet condensate already at two-loop level [ref] (also cf. [ref] ), and further signals that interpreting this point as the physical critical temperature is incorrect.
Combining thermal resummation and gauge invariance for electroweak phase transition · Critical temperature · 0.97
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The focus on small gauge parameters is also supported by various observations in specific models, in which gauge-invariant analyses appear to agree well with the Landau gauge [ref] .
Theoretical uncertainties for cosmological first-order phase transitions · Gauge dependence · 1.00
Cites it as background 8 papers
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This has been discussed in Refs. [ref] .
Theoretical uncertainties for cosmological first-order phase transitions · Dimensionally-reduced recipe for thermodynamics · 0.96
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Concerns were raised that the direct minimisation method led to gauge-dependent results [ref] , while strict $ħ$-expansions appeared to lead to IR divergences [ref] .
Perturbative effective field theory expansions for cosmological phase transitions · Discussion · 0.84
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Following earlier studies [ref] , Ref. [ref] addressed the possibility of producing a consistent, order-by-order gauge-invariant result in the perturbative expansion of the $V_eff$ and $S_eff$.
Phase Transitions and Gauge Artifacts in an Abelian Higgs Plus Singlet Model · Introduction · 0.81
Discussion
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