REVIEW
Constraining Type II 2HDM in Light of LHC Higgs Searches
High Energy Physics - Phenomenology · Submitted 30 Apr 2013 · 65 references
Pith's verdict: A competent, well-documented map of the Type II 2HDM survival regions under the 126 GeV Higgs data; the qualitative structure is trustworthy, the exact window edges are box-cut artifacts.
T0 · AI review
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Referee report
The paper
The paper claims
The LHC's 126 GeV Higgs signal squeezes the Type II two-Higgs-doublet model into narrow mixing-angle windows, whichever CP-even state the resonance is.
The reading
What carries the argument
Everything rests on the coupling-scaling table: each Higgs couples to $WW/ZZ$ with strength $s$ for $h^0$ and $s$ for $H^0$, to up-type quarks with $s$ and $s$ respectively, and to down-type quarks and leptons with $s$ and $s$, all relative to the SM. Because the $Z_2$ symmetry is imposed without a soft-breaking $m_{12}$ term, there is no decoupling limit, and perturbativity plus unitarity cap the heavy Higgs masses near 800 GeV. The scan over $m_A$, $m_{H^pm}$, $s$ and $s$ is filtered by 2HDMC and HiggsBounds, then by $S$, $T$ and $R_b$, then by SuperIso flavor observables, and finally intersected with the hard requirement that the gluon-fusion rates into $s$ and $VV$ land in the observed windows.
Extended reading notes
Core claim
Splitting the analysis into two scenarios, the paper finds sharply different survivors. If the light CP-even state $h^0$ is the 126 GeV resonance, the allowed region is either a narrow strip at $s = 1 - s$ with $s = 1 - s$ up to 4, or an extended region with $0.55 < s < 0.9$ and $1.5 < s < 4$; the heavy masses $m_H$, $m_A$ and $m_{H^pm}$ are largely unconstrained, and perturbativity of the quartic couplings caps $s$ at about 4, so the bottom-quark loop never dominates gluon fusion. If instead the heavy CP-even state $H^0$ is the 126 GeV resonance, the survivors sit near $s = 1 - s$ with $s$ up to about 8, or in an extended band $-0.8 s -0.05$ where $s$ can run to 30 or more; here $m_A$ and $m_{H^pm}$ are driven nearly degenerate by the $Delta ho$ constraint, because both $m_h$ and $m_H$ are small in this scenario. Flavor bounds barely touch the $h^0$-126 case but cut the $H^0$-126 case down to $s 10$, $m_h > 50$ GeV and $m_{H^pm} > 300$ GeV. Across both scenarios the diphoton and $VV$ rates come out positively correlated, with $s : VV 1$ for the normalized cross sections.
Load-bearing premise
The load-bearing premise is that 'consistent with the observed Higgs signal' can be represented by two independent hard boxes, $0.7 < s(gg h^0/H^0 s)/SM < 1.5$ and $0.6 < s(gg h^0/H^0 VV)/SM < 1.3$, applied channel by channel without a joint likelihood, without inter-channel correlations and without theory uncertainties; every favored region in the paper is the intersection of the survival constraints with those boxes.
Editorial extensions
If this is right
- If the 126 GeV state is $h^0$, a heavy CP-even Higgs found between 300 and 650 GeV would force $s$ to be very close to $s$, meaning the 126 GeV state has essentially SM-like gauge couplings.
- In the $H^0$-126 case, any observation of the charged Higgs should come with a pseudoscalar of nearly the same mass, since $Delta ho$ ties $m_A$ and $m_{H^pm}$ together.
- A measured diphoton excess should be accompanied by a comparable $WW/ZZ$ excess rather than by a large $s$ rate, since the two channels track each other at roughly unit ratio.
- Flavor measurements already imply $m_{H^pm} > 300$ GeV in both scenarios, so a light charged Higgs below that scale would contradict the combined fit.
- Because the model has no decoupling limit, discovering any one of the extra scalars would sharply narrow the remaining parameter space rather than merely pushing the others out of reach.
Reading between the lines
- The paper's sharp boundaries are boundaries of a rectangular cut, not of a likelihood; a correlated multi-channel fit to the same data would likely blur the edges of the dark-red regions and could admit slivers the paper rules out.
- The near-degeneracy $m_A m_{H^pm}$ in the $H^0$-126 case is a prediction of custodial symmetry rather than of the Higgs data, so it doubles as a consistency check: a future split between these two masses would point to new custodial-symmetry-breaking states beyond the two doublets.
- Because the analysis assumes no soft $Z_2$ breaking, the absence of a decoupling limit is a choice, not a result; allowing $m_{12} 0$ would reopen the heavy-mass region and could weaken the upper bound near 800 GeV.
- The $s : VV 1$ correlation is the most transferable statement here: it applies to any model where a single CP-even state carries both the gluon-fusion production and the gauge-boson decay, so it can be used as a quick discriminant before a full fit.
Original abstract
We study the implication of the LHC Higgs search results on the Type II Two Higgs-Doublet Model. In particular, we explore the scenarios in which the observed 126 GeV Higgs signal is interpreted as either the light CP-even Higgs $h^0$ or the heavy CP-even Higgs $H^0$. Imposing both theoretical and experimental constraints, we analyze the surviving parameter regions in $m_H$ ($m_h$), $m_A$, $m_{H^\pm}$, $\tan\beta$ and $\sin(\beta - \alpha)$. We further identify the regions that could accommodate a 126 GeV Higgs with cross sections consistent with the observed Higgs signal. We find that in the $h^0$-126 case, we are restricted to narrow regions of $\sin(\beta-\alpha) \approx \pm 1$ with $\tan\beta$ up to 4, or an extended region with $0.55 < \sin(\beta-\alpha) < 0.9$ and $1.5 < \tan\beta < 4$. The values of $m_H$, $m_A$ and $m_{H^\pm}$, however, are relatively unconstrained. In the $H^0$-126 case, we are restricted to a narrow region of $\sin(\beta-\alpha) \sim 0$ with $\tan\beta$ up to about 8, or an extended region of $\sin(\beta-\alpha) $ between $-0.8$ to $-0.05$, with $\tan\beta$ extended to 30 or higher. $m_A$ and $m_{H^\pm}$ are nearly degenerate due to $\Delta\rho$ constraints. Imposing flavor constraints shrinks the surviving parameter space significantly for the $H^0$-126 case, limiting $\tan\beta \lesssim 10$, but has little effect in the $h^0$-126 case. We also investigate the correlation between $\gamma\gamma$, $VV$ and $bb/\tau\tau$ channels. $\gamma\gamma$ and $VV$ channels are most likely to be highly correlated with $\gamma\gamma:VV \sim 1$ for the normalized cross sections.
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 study the implication of the LHC Higgs search results on the Type II Two Higgs-Doublet Model. In particular, we explore the scenarios in which the observed 126 GeV Higgs signal is interpreted as either the light CP-even Higgs $h^0$ or the heavy CP-even Higgs $H^0$. Imposing both theoretical and experimental constraints, we analyze the surviving parameter regions in $m_H$ ($m_h$), $m_A$, $m_{H^\pm}$, $\tan\beta$ and $\sin(\beta - \alpha)$. We further identify the regions that could accommodate a 126 GeV Higgs with cross sections consistent with the observed Higgs signal. We find that in the $h^0$-126 case, we are restricted to narrow regions of $\sin(\beta-\alpha) \approx \pm 1$ with $\tan\beta$ up to 4, or an extended region with $0.55 < \sin(\beta-\alpha) < 0.9$ and $1.5 < \tan\beta < 4$. The values of $m_H$, $m_A$ and $m_{H^\pm}$, however, are relatively unconstrained. In the $H^0$-126 case, we are restricted to a narrow region of $\sin(\beta-\alpha) \sim 0$ with $\tan\beta$ up to about 8, or an extended region of $\sin(\beta-\alpha) $ between $-0.8$ to $-0.05$, with $\tan\beta$ extended to 30 or higher. $m_A$ and $m_{H^\pm}$ are nearly degenerate due to $\Delta\rho$ constraints. Imposing flavor constraints shrinks the surviving parameter space significantly for the $H^0$-126 case, limiting $\tan\beta \lesssim 10$, but has little effect in the $h^0$-126 case. We also investigate the correlation between $\gamma\gamma$, $VV$ and $bb/\tau\tau$ channels. $\gamma\gamma$ and $VV$ channels are most likely to be highly correlated with $\gamma\gamma:VV \sim 1$ for the normalized cross sections.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | We study the implication of the LHC Higgs search results on the Type II Two Higgs-Doublet Model. | contribution 0.99 | 0.93 | 0.03 | asserted 0.73 |
| s1 | In particular, we explore the scenarios in which the observed 126 GeV Higgs signal is interpreted as either the light CP-even Higgs $h^0$ or the heavy CP-even Higgs $H^0$. | contribution 0.94 | 0.84 | 0.03 | asserted 0.58 |
| s2 | Imposing both theoretical and experimental constraints, we analyze the surviving parameter regions in $m_H$ ($m_h$), $m_A$, $m_{H^\pm}$, $\tan\beta$ and $\sin(\beta - \alpha)$. | method 0.88 | 0.94 | 0.04 | asserted 0.93 |
| s3 | We further identify the regions that could accommodate a 126 GeV Higgs with cross sections consistent with the observed Higgs signal. | contribution 0.80 | 0.92 | 0.08 | hedged possibility 0.83 |
| s4 | We find that in the $h^0$-126 case, we are restricted to narrow regions of $\sin(\beta-\alpha) \approx \pm 1$ with $\tan\beta$ up to 4, or an extended region with $0.55 < \sin(\beta-\alpha) < 0.9$ and $1.5 < \tan\beta < 4$. | result 1.00 | 0.96 | 0.30 | asserted 1.00 |
| s5 | The values of $m_H$, $m_A$ and $m_{H^\pm}$, however, are relatively unconstrained. | result 1.00 | 0.87 | 0.07 | asserted 1.00 |
| s6 | In the $H^0$-126 case, we are restricted to a narrow region of $\sin(\beta-\alpha) \sim 0$ with $\tan\beta$ up to about 8, or an extended region of $\sin(\beta-\alpha) $ between $-0.8$ to $-0.05$, with $\tan\beta$ extended to 30 or higher. | result 1.00 | 0.95 | 0.15 | asserted 1.00 |
| s7 | $m_A$ and $m_{H^\pm}$ are nearly degenerate due to $\Delta\rho$ constraints. | result 1.00 | 0.74 | 0.05 | asserted 1.00 |
| s8 | Imposing flavor constraints shrinks the surviving parameter space significantly for the $H^0$-126 case, limiting $\tan\beta \lesssim 10$, but has little effect in the $h^0$-126 case. | result 0.99 | 0.92 | 0.13 | asserted 1.00 |
| s9 | We also investigate the correlation between $\gamma\gamma$, $VV$ and $bb/\tau\tau$ channels. | contribution 0.98 | 0.91 | 0.03 | asserted 0.73 |
| s10 | $\gamma\gamma$ and $VV$ channels are most likely to be highly correlated with $\gamma\gamma:VV \sim 1$ for the normalized cross sections. | result 0.99 | 0.84 | 0.06 | hedged possibility 0.98 |
What was examined, and what was not
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- P abstract
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Figures
Showing 13 of the paper's 19 figures. See all figures in the PDF ↗ Figures reproduced from arXiv:1305.0002 by the authors.
References
How the literature uses it
73 arXiv papers cite this in 109 sentences
Papers citing it · 57 sentences without a confident label
Contests it 1 paper
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The scan-based analysis of [ref] simply misses the scenarios where these relations are fulfilled.
Status of the two-Higgs-doublet model of type II · Conclusions · contest 0.88
Uses its data or values 1 paper
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Also shown in Table [ref] are the preferred regions in $sin(β-α)$ once all the theoretical and experimental constraints are imposed, following Ref. [ref] .
Exotic Decays Of A Heavy Neutral Higgs Through HZ/AZ Channel · Implications for the Type II 2HDM · 0.91
Compares with it 1 paper
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Where appropriate, we compare our results with those of [ref] .
Status of the two-Higgs-doublet model of type II · Introduction · 1.00
Cites it as support 4 papers
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It was shown in Ref. [ref] that in the Type II 2HDM with $Z_2$ symmetry, imposing all experimental and theoretical constraints still leaves large regions in the parameter space that permit such exotic decays with unsuppressed decay branching fractions.
Light Charged Higgs Bosons to AW/HW via Top Decay · Theoretical Motivation · 1.00
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It was shown in Ref. [ref] that in the Type II 2HDM with $Z_2$ symmetry, imposing all experimental and theoretical constraints still leaves sizable regions in the parameter space.
Exotic Decays Of A Heavy Neutral Higgs Through HZ/AZ Channel · Scenarios with large $H→Z$ or $→H Z$ · 0.99
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The recent global fits of the LHC data in the 2HDM context [ref] certifies that alignment is indeed a reasonable assumption.
Search for a 'stable alignment limit' in two Higgs-doublet models · The scalar potential · 1.00
Cites it as background 38 papers
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Focused on Type II [ref] , or Type I and II [ref] , the allowed parameter space has been obtained with electroweak precision constraints and flavor bounds.
Two Higgs doublet models for the LHC Higgs boson data at $\sqrt{s}=$ 7 and 8 TeV · Introduction · 0.94
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A large number of papers [ref] performed fits of current data for the 125.5 GeV Higgs-like state (as per the status post Moriond 2013) within the context of 2HDMs, and investigated the consequent phenomenology of the other Higgs states present in the models.
Constraints on and future prospects for Two-Higgs-Doublet Models in light of the LHC Higgs signal · Introduction · 0.87
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A simple extension of the scalar sector of the SM is to add another doublet: this gives rise to the well known 2HDM, which has been thoroughly studied with respect to the LHC (with a lighter scalar in [ref] , and a heavier one in [ref] ).
Searching for a lighter Higgs: parametrisation and sample tests · Two Higgs Doublet Model · 0.97
What it cites · 43 sentences without a confident label
Uses the method or tool of 7 papers
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We used the 2HDMC 1.2beta [ref] which tested if each parameter point fulfills the theoretical and experimental constraints implemented in HiggsBounds 3.8 [ref] .
New HiggsBounds from LEP and the Tevatron · Analysis Method · 1.00
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We used the 2HDMC 1.2beta [ref] which tested if each parameter point fulfills the theoretical and experimental constraints implemented in HiggsBounds 3.8 [ref] .
2HDMC - Two-Higgs-Doublet Model Calculator · Analysis Method · 1.00
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To do this, we employed the program SuperIso 3.3 [ref] , which incorporates, among other things, bounds from $B→X_sγ, ΔM_B_d,$ $B^- →τ^- ν̅_τ$, $D_s^±→τ^±(μ^±)ν$, $B→τ^+τ^-$ and $B_d,s →μ^+ μ^-$ [ref] .
Evidence for B- -> tau- nu_tau-bar with a Hadronic Tagging Method Using the Full Data Sample of Belle · Theoretical and Experimental Constraints · 0.88
Uses data or values from 4 papers
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[ref] : [equation] in which we have taken the tighter limits from the ATLAS and CMS results, as well as the tighter results for the$WW$and$ZZ$channel.
Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC · Analysis Method · 0.99
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We also incorporated the latest Higgs search results at the LHC [ref] .
Search for neutral Higgs bosons decaying to tau pairs in pp collisions at sqrt(s) = 7 TeV · Theoretical and Experimental Constraints · 0.81
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We also incorporated the latest Higgs search results at the LHC [ref] .
Search for charged Higgs bosons decaying via H+ -> tau nu in top quark pair events using pp collision data at sqrt(s) = 7 TeV with the ATLAS detector · Theoretical and Experimental Constraints · 0.81
Cites as support 2 papers
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Small values of $tanβ$ is disfavored by the perturbativity of top Yukawa coupling [ref] , $R_b$ [ref] , and the flavor constraints [ref] .
Flavor constraints on two-Higgs-doublet models with general diagonal Yukawa couplings · Parameter spaces · 0.97
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Small values of $tanβ$ is disfavored by the perturbativity of top Yukawa coupling [ref] , $R_b$ [ref] , and the flavor constraints [ref] .
Constraining General Two Higgs Doublet Models by the Evolution of Yukawa Couplings · Parameter spaces · 0.97
Cites as background 13 papers
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The authors of Ref. [ref] and Ref. [ref] did the initial study of looking at the $tanβ-sinα$ plane where the observed Higgs signal is feasible, interpreting the discovered scalar as either the light or the heavy CP-even Higgs boson.
Could the LHC two-photon signal correspond to the heavier scalar in two-Higgs-doublet models? · Introduction · 0.92
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The authors of Ref. [ref] and Ref. [ref] did the initial study of looking at the $tanβ-sinα$ plane where the observed Higgs signal is feasible, interpreting the discovered scalar as either the light or the heavy CP-even Higgs boson.
Implications of the LHC two-photon signal for two-Higgs-doublet models · Introduction · 0.92
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Ref. [ref] fit the observed Higgs signals in various 2HDM scenarios, taken into account theoretical and experimental constraints.
Constraining parameter space in type-II two-Higgs doublet model in light of a 126 GeV Higgs boson · Introduction · 0.93
Discussion
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