REVIEW
Electroweak Phase Transition in 2HDM under Higgs, Z-pole, and W precision measurements
High Energy Physics - Phenomenology · Submitted 11 Apr 2022 · 85 references
Pith's verdict: A competent, timely extension of the authors' own 2HDM phase-transition scan to include the CDF-II W mass; the physics story is sound, but the headline green region rests on two 95% cuts that should have been one joint fit.
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Referee report
The paper
The paper claims
Under current data, both Type-I and Type-II two-Higgs-doublet models can simultaneously produce a strong first-order electroweak phase transition, satisfy Higgs and Z-pole precision measurements, and account for the CDF-II W boson mass, all
The reading
What carries the argument
The load-bearing object is the pair of mass splittings $Delta m_A = m_A - m_H$ and $Delta m_C = m_{H^+} - m_H$. These enter the oblique parameters $S$, $T$ and $U$ through one-loop gauge-boson self-energies, and $T$ carries by far the tightest current bound, so the Z-pole data effectively pin the splitting pattern; the same $S,T,U$ then feed the 2HDM prediction for $m_W$ through the standard relation $m_W^2(1 - m_W^2/m_Z^2) = pi alpha/(sqrt(2) G_F)(1 + Delta r)$, with a small extra term from the modified triple-Higgs coupling. The phase transition side uses the finite-temperature effective potential, tree level plus Coleman-Weinberg plus counterterms plus thermal corrections, and the criterion that the minimum of the potential jump discontinuously as the temperature falls, with $v_c/T_c > 0.9$ to avoid washing out any generated baryon number. The numerical engine is BSMPT, which tracks the minima and reports the critical temperature and the strength of the transition.
Extended reading notes
Core claim
The central claim is a conjunction, established by a large numerical scan rather than by an analytic identity. The authors scan six 2HDM parameters (with $|cos(beta-alpha)| < 0.5$, $m_{A,H^+}$ and $m_H$ up to 1.5 TeV, $tan beta$ from 0.2 to 50), keep points that pass vacuum stability, unitarity, perturbativity, $B$-physics, LEP and LHC direct searches, and current Higgs and Z-pole precision data, and then require a strong first-order transition using the washout criterion $xi_c = v_c/T_c > 0.9$ computed with the public code BSMPT. On top of that they impose the CDF-II W mass at 95% confidence, which in their treatment corresponds to a shift $Delta m_W in (36.3, 103.4)$ MeV. The result is that a non-empty set of points survives all of it in both model types: roughly $m_H$ between 125 and 950 GeV with $tan beta$ from 1 to 50 and splittings $Delta m_{A/C}$ in $(-400, 400)$ GeV for Type-I, and $m_H$ between 125 and 900 GeV with $tan beta$ from 1 to 12 and splittings in $(-200, 300)$ GeV for Type-II. The authors also show the reverse side: if future CEPC-type measurements come out Standard-Model-like, the surviving region shrinks to slices at $Delta m_A = 0$ or $Delta m_C = Delta m_A$ that do not overlap the W-mass-compatible region, so the CDF-II explanation and a Standard-Model-consistent future cannot both hold in this model.
Load-bearing premise
The Z-pole oblique-parameter constraint and the CDF-II W mass are imposed as two separate 95% confidence cuts, which the authors themselves flag in Section 2.4 as a simplification standing in for a proper joint fit over correlated observables.
Editorial extensions
If this is right
- If the paper is right, new scalars with masses of order 100 GeV to about 1 TeV, split by a few hundred GeV, are compatible with every current precision measurement while still driving a strong first-order electroweak transition.
- The W mass, the Z-pole oblique parameters and the phase transition strength are then not independent observables: measuring any one of them constrains the other two through the shared splittings $Delta m_A$ and $Delta m_C$.
- A future lepton collider measuring $S,T,U$ at the percent level and improving Higgs coupling precision would either observe a deviation from the Standard Model or exclude the region that explains the CDF-II W mass together with a strong first-order transition.
- Conversely, if the CDF-II W mass is real and the 2HDM is the correct description, a deviation from Standard-Model predictions must appear at those future machines with high confidence.
Reading between the lines
- Because $m_W$ and the Z-pole observables are generated by the same radiative corrections, a genuine joint fit over both data sets would very likely shrink the region the paper calls allowed; the surviving slivers may partly reflect the choice to impose two separate 95% confidence cuts rather than one combined likelihood.
- The paper's own logic makes the scenario fragile in a useful way: if an independent W mass measurement lands on the Standard-Model value, the W-compatible region empties and only the phase-transition-only region remains, which is a clean and near-term test of the whole construction.
- The threshold $v_c/T_c > 0.9$ is a perturbative proxy for whether baryons survive the transition; a lattice or higher-order treatment of the 2HDM transition could move that boundary and therefore shift which mass splittings count as viable.
- A first-order transition with these splittings would also source gravitational waves from bubble collisions and sound waves, so a stochastic background search offers a channel that is independent of the collider program described here.
Original abstract
In this work we revisit the existence of a strong first order electroweak phase transition (SFOEWPT) and recent $m_W$ precision measurement in the Type-I and Type-II 2HDMs. The O(100) GeV new scalars in 2HDMs are favored by SFOEWPT, which is necessary for electroweak baryogenesis, and observed $m_W$ shift as well. % We find that under current constraints, both Type-I and Type-II 2HDM can explain the SFOEWPT, Z-pole, Higgs precision measurements and $m_W$ precision measurement of CDF-II at same time, and all these precision measurements are sensitive to heavy Higgs mass splitting in 2HDM. The allowed regions are $\Delta m_{A/C} \in (-400, 400) GeV, \tanb\in(1,50)$, and $\Delta m_{A/C} \in (-200, 300) GeV, \tanb\in(1,12)$ for Type-I and Type-II 2HDM respectively. Furthermore future lepton collider measurements on Higgs and $Z$ boson properties can explore this scenario in more detail or even rule out it.
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
In this work we revisit the existence of a strong first order electroweak phase transition (SFOEWPT) and recent $m_W$ precision measurement in the Type-I and Type-II 2HDMs. The O(100) GeV new scalars in 2HDMs are favored by SFOEWPT, which is necessary for electroweak baryogenesis, and observed $m_W$ shift as well. % We find that under current constraints, both Type-I and Type-II 2HDM can explain the SFOEWPT, Z-pole, Higgs precision measurements and $m_W$ precision measurement of CDF-II at same time, and all these precision measurements are sensitive to heavy Higgs mass splitting in 2HDM. The allowed regions are $\Delta m_{A/C} \in (-400, 400) GeV, \tanb\in(1,50)$, and $\Delta m_{A/C} \in (-200, 300) GeV, \tanb\in(1,12)$ for Type-I and Type-II 2HDM respectively. Furthermore future lepton collider measurements on Higgs and $Z$ boson properties can explore this scenario in more detail or even rule out it.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | In this work we revisit the existence of a strong first order electroweak phase transition (SFOEWPT) and recent $m_W$ precision measurement in the Type-I and Type-II 2HDMs. | contribution 0.99 | 0.69 | 0.06 | unclear 0.59 |
| s1 | The O(100) GeV new scalars in 2HDMs are favored by SFOEWPT, which is necessary for electroweak baryogenesis, and observed $m_W$ shift as well. % We find that under current constraints, both Type-I and Type-II 2HDM can explain the SFOEWPT, Z-pole, Higgs precision measurements and $m_W$ precision measurement of CDF-II at same time, and all these precision measurements are sensitive to heavy Higgs mass splitting in 2HDM. | result 0.87 | 0.51 | 0.73 | asserted 0.94 |
| s2 | The allowed regions are $\Delta m_{A/C} \in (-400, 400) GeV, \tanb\in(1,50)$, and $\Delta m_{A/C} \in (-200, 300) GeV, \tanb\in(1,12)$ for Type-I and Type-II 2HDM respectively. | result 1.00 | 0.86 | 0.24 | asserted 1.00 |
| s3 | Furthermore future lepton collider measurements on Higgs and $Z$ boson properties can explore this scenario in more detail or even rule out it. | future work 0.98 | 0.16 | 0.06 | hedged possibility 0.93 |
What was examined, and what was not
- arXiv listing abstract v1
- full text
- figures and tables
- references and citing sentences
- relations to other papers
- P abstract
- S sections
- T body sentences
- C citations
- R cross-paper relations
Figures
Figures reproduced from arXiv:2204.05085 by the authors.
References
How the literature uses it
63 arXiv papers cite this in 70 sentences
Papers citing it · 32 sentences without a confident label
Cites it as background 37 papers
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Extensive studies have been carried out in the literature to explain the CDF-2 $W$-boson mass anomaly with low-dimensional scalar multiplets, which include a scalar singlet [ref] , a second Higgs doublet [ref] , and a scalar triplet [ref] .
$W$-boson Mass Anomaly from High-Dimensional Scalar Multiplets · Introduction · 0.90
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Some possible explanations to the $W$ boson mass shift can arise at tree-level [ref] , or at loop level [ref] , along with the prospect of reconciling one or more discrepancies [ref] such as flavor anomalies and dark matter.
$W$ boson mass shift, dark matter and $(g-2)_\ell$ in a scotogenic-Zee model · Introduction · 0.89
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There have been many attempts to resolve the W mass anomaly, see e.g. [ref] .
Constraints from New CDF II W-Boson Mass On Top-Bottom Seesaw and the TopFlavor Models · Introduction · 0.99
What it cites · 51 sentences without a confident label
Uses the method or tool of 1 paper
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This method has been numerically implemented in public package $$ [ref] .
BSMPT - Beyond the Standard Model Phase Transitions -A Tool for the Electroweak Phase Transition in Extended Higgs Sectors · Phase transition in the 2HDM · 1.00
Uses data or values from 4 papers
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Here $m_W^SM=80.357 GeV ±4_inputs ±$ $4_theory MeV$ [ref] , $S, T, U$ are oblique parameters in the 2HDM [ref] , and $δρ^2HDM =|λ_hhh^2HDM|^2/16 π^2 m_h^2$ are higher order 2HDM effects from enhanced Higgs boson self-interactions.
Type-II 2HDM under the Precision Measurements at the $Z$-pole and a Higgs Factory · $m_W$ in the 2HDM · 1.00
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We adopt the Higgs measurements results presented in Table 3 in Ref. [ref] .
Type-I 2HDM under the Higgs and Electroweak Precision Measurements · Z-pole and Higgs precision measurements · 1.00
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The search for pair-produced charged Higgs bosons at the Large Electron-Positron Collider (LEP) imposes a lower bound of 80 on the mass of the charged Higgs boson [ref] , and LEP searches for $AH$ production constrain the sum of the masses $m_H + m_A > 209$ [ref] .
Search for Charged Higgs bosons: Combined Results Using LEP Data · Direct searches at LEP and LHC · 0.94
Cites as support 3 papers
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Furthermore, these light extra scalar can induce a positive $m_W$ shift [ref] and modify the predictions on the Z-pole observables like the oblique parameters $S$, $T$ and $U$ via one-loop contributions to the $W$ and $Z$ self-energies.
Delta r in the Two-Higgs-Doublet Model at full one loop level -- and beyond · Introduction · 0.99
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Therefore the EW phase transition can be first order and strong enough for the baryogenesis [ref] .
Strong first order electroweak phase transition in 2HDM confronting future Z & Higgs factories · Introduction · 0.98
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Extending the Higgs sector by a singlet scalar seems to be the simplest choice, but it is difficult for such model to explain the observed $m_W$ under current limits [ref] .
Delta r and the W-boson mass in the Singlet Extension of the Standard Model · Introduction · 0.98
Cites as background 24 papers
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For the Higgs precision measurements, the works [ref] have discussed them for the case of 2HDM systematically.
Type-I 2HDM under the Higgs and Electroweak Precision Measurements · SFOEWPT under Higgs, Z and W precision measurements · 0.88
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For the Higgs precision measurements, the works [ref] have discussed them for the case of 2HDM systematically.
Learning from Higgs Physics at Future Higgs Factories · SFOEWPT under Higgs, Z and W precision measurements · 0.88
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For the Higgs precision measurements, the works [ref] have discussed them for the case of 2HDM systematically.
Type-II 2HDM under the Precision Measurements at the $Z$-pole and a Higgs Factory · SFOEWPT under Higgs, Z and W precision measurements · 0.88
Discussion
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