REVIEW
Bottom-Up Approach to Moduli Dynamics in Heavy Gravitino Scenario : Superpotential, Soft Terms and Sparticle Mass Spectrum
High Energy Physics - Phenomenology · Submitted 6 Apr 2005 · 62 references
Pith's verdict: A useful bottom-up argument that CP alignment picks out KKLT-type moduli potentials, but the 'uniqueness' is a naturalness claim dressed as a derivation.
T0 · AI review
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Referee report
The paper
The paper claims
Demanding no physical CP phase in anomaly-mediated gaugino masses fixes the moduli superpotential to a KKLT-like form, or a two-exponential racetrack, and that same potential stabilizes the moduli and makes the two mediations comparable.
The reading
What carries the argument
The argument is carried by the ratio of the two supersymmetry-breaking F terms, $F_~varphi/F_X$, which controls the relative phase of the anomaly and moduli contributions to $M_lambda = F_X/(2X_R)+(beta_g/g),F_~varphi$. With a shift-symmetric Kähler potential $K=K(X+X^dagger)$, the ratio is real exactly when $W_X/W$ is real; minimizing the scalar potential then forces $W_{XX}/W_X$ to be real at the extremum, and integrability makes it a real constant. That is what produces $W=ae^{-bX}+c$, and a Kähler transformation produces the racetrack form. The same minimization gives $bX_R$ of order 10, so the modulus is heavier than the gravitino and its F-term is suppressed, leaving $F_X/(2X_R)$ comparable to the one-loop anomaly term.
Extended reading notes
Core claim
The paper's central claim is that the moduli superpotential is fixed, up to a Kähler transformation, by a low-energy CP requirement: in the heavy-gravitino regime the anomaly-mediated gaugino mass $F_~varphi$ and the moduli-mediated mass $F_X/(2X_R)$ are both present, and if their relative phase is not aligned the gaugino masses carry physical CP phases. Requiring alignment at the extremum, and requiring the condition to be integrable as a function of the modulus, gives $W=ae^{-bX}+c$ with real $b$; a Kähler transformation turns this into the racetrack $W=a_1e^{-b_1X}+a_2e^{-b_2X}$. The paper then shows that this same superpotential stabilizes the modulus at $bX_R$ of order 10, breaks supersymmetry, and makes the moduli and anomaly contributions to soft masses comparable. The resulting MSSM spectrum has weak-scale gauginos that are much closer in mass than in minimal supergravity, and a lightest neutralino that is a sizable mixture of gaugino and higgsino components.
Load-bearing premise
The uniqueness step assumes that the reality of $W_{XX}/W_X$ must hold as a function of the modulus, not merely be arranged by tuning at one vacuum point; if accidental reality at a point is allowed, many superpotentials could have aligned gaugino phases.
Editorial extensions
If this is right
- If the argument holds, the gravitino can be heavy enough, around 10 TeV, to suppress the gravitino problem, while moduli masses an order of magnitude or more above it allow the moduli to decay before nucleosynthesis.
- The moduli superpotential is no longer a free model-building choice: the KKLT exponential-plus-constant form and the two-exponential racetrack are selected by the requirement that gaugino masses carry no physical CP phase.
- At the weak scale the three gauginos are predicted to be rather degenerate, with a lighter gluino and heavier bino than in universal supergravity, which changes collider mass patterns.
- The lightest neutralino is a considerable bino-higgsino admixture, so its annihilation, direct detection, and collider signatures differ from pure bino or pure higgsino dark matter.
- Because moduli and anomaly mediation are comparable, the spectrum interpolates between pure anomaly mediation and moduli domination, and the tachyonic-slepton problem of pure anomaly mediation can be ameliorated.
Reading between the lines
- The CP-alignment criterion is likely to be sharper in a single-modulus model than in the multi-modulus case; if several moduli participate in supersymmetry breaking, requiring all relative phases to align could either fix a more restrictive potential or expose the single-field derivation as a special case.
- The predicted near-degenerate gaugino masses and mixed neutralino give a concrete collider target: measuring the bino, wino, and gluino mass ratios at the LHC or a future lepton collider could separate this hybrid mediation from both minimal supergravity and pure anomaly mediation.
- If the lightest neutralino is a several-hundred-GeV bino-higgsino mixture, direct-detection and indirect-search rates should be enhanced relative to a pure bino of the same mass; a null result in that window would put pressure on the scenario.
- The WMAP comparison assumes a standard thermal history; because moduli decay can dilute or regenerate neutralinos, a full non-thermal calculation is the natural next step and could shift the allowed $F_~varphi$ range.
Original abstract
The physics of moduli fields is examined in the scenario where the gravitino is relatively heavy with mass of order 10 TeV, which is favored in view of the severe gravitino problem. The form of the moduli superpotential is shown to be determined, if one imposes a phenomenological requirement that no physical CP phase arise in gaugino masses from conformal anomaly mediation. This bottom-up approach allows only two types of superpotential, each of which can have its origins in a fundamental underlying theory such as superstring. One superpotential is the sum of an exponential and a constant, which is identical to that obtained by Kachru et al (KKLT), and the other is the racetrack superpotential with two exponentials. The general form of soft supersymmetry breaking masses is derived, and the pattern of the superparticle mass spectrum in the minimal supersymmetric standard model is discussed with the KKLT-type superpotential. It is shown that the moduli mediation and the anomaly mediation make comparable contributions to the soft masses. At the weak scale, the gaugino masses are rather degenerate compared to the minimal supergravity, which bring characteristic features on the superparticle masses. In particular, the lightest neutralino, which often constitutes the lightest superparticle and thus a dark matter candidate, is a considerable admixture of gauginos and higgsinos. We also find a small mass hierarchy among the moduli, gravitino, and superpartners of the standard-model fields. Cosmological implications of the scenario are briefly described.
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 physics of moduli fields is examined in the scenario where the gravitino is relatively heavy with mass of order 10 TeV, which is favored in view of the severe gravitino problem. The form of the moduli superpotential is shown to be determined, if one imposes a phenomenological requirement that no physical CP phase arise in gaugino masses from conformal anomaly mediation. This bottom-up approach allows only two types of superpotential, each of which can have its origins in a fundamental underlying theory such as superstring. One superpotential is the sum of an exponential and a constant, which is identical to that obtained by Kachru et al (KKLT), and the other is the racetrack superpotential with two exponentials. The general form of soft supersymmetry breaking masses is derived, and the pattern of the superparticle mass spectrum in the minimal supersymmetric standard model is discussed with the KKLT-type superpotential. It is shown that the moduli mediation and the anomaly mediation make comparable contributions to the soft masses. At the weak scale, the gaugino masses are rather degenerate compared to the minimal supergravity, which bring characteristic features on the superparticle masses. In particular, the lightest neutralino, which often constitutes the lightest superparticle and thus a dark matter candidate, is a considerable admixture of gauginos and higgsinos. We also find a small mass hierarchy among the moduli, gravitino, and superpartners of the standard-model fields. Cosmological implications of the scenario are briefly described.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | The physics of moduli fields is examined in the scenario where the gravitino is relatively heavy with mass of order 10 TeV, which is favored in view of the severe gravitino problem. | background 0.84 | 0.25 | 0.05 | asserted 0.73 |
| s1 | The form of the moduli superpotential is shown to be determined, if one imposes a phenomenological requirement that no physical CP phase arise in gaugino masses from conformal anomaly mediation. | result 0.73 | 0.84 | 0.21 | asserted 0.99 |
| s2 | This bottom-up approach allows only two types of superpotential, each of which can have its origins in a fundamental underlying theory such as superstring. | result 0.72 | 0.76 | 0.20 | asserted 0.89 |
| s3 | One superpotential is the sum of an exponential and a constant, which is identical to that obtained by Kachru et al (KKLT), and the other is the racetrack superpotential with two exponentials. | result 0.95 | 0.62 | 0.17 | asserted 0.99 |
| s4 | The general form of soft supersymmetry breaking masses is derived, and the pattern of the superparticle mass spectrum in the minimal supersymmetric standard model is discussed with the KKLT-type superpotential. | contribution 0.89 | 0.92 | 0.14 | asserted 0.95 |
| s5 | It is shown that the moduli mediation and the anomaly mediation make comparable contributions to the soft masses. | result 1.00 | 0.90 | 0.18 | asserted 1.00 |
| s6 | At the weak scale, the gaugino masses are rather degenerate compared to the minimal supergravity, which bring characteristic features on the superparticle masses. | result 0.97 | 0.79 | 0.12 | asserted 0.97 |
| s7 | In particular, the lightest neutralino, which often constitutes the lightest superparticle and thus a dark matter candidate, is a considerable admixture of gauginos and higgsinos. | result 0.92 | 0.78 | 0.08 | asserted 0.85 |
| s8 | We also find a small mass hierarchy among the moduli, gravitino, and superpartners of the standard-model fields. | result 1.00 | 0.94 | 0.09 | asserted 1.00 |
| s9 | Cosmological implications of the scenario are briefly described. | contribution 0.57 | 0.70 | 0.03 | unclear 0.69 |
What was examined, and what was not
- arXiv listing abstract v3
- full text
- figures and tables
- references and citing sentences
- relations to other papers
- P abstract
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Figures
Figures reproduced from arXiv:hep-ph/0504036 by the authors.
References
How the literature uses it
47 arXiv papers cite this in 59 sentences
Papers citing it · 42 sentences without a confident label
Compares with it 1 paper
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This is contrast to the so-called mirage mediation scheme arising for instance in the original KKLT scenario [ref] , where both are of the same order of magnitude.
String GUT Scenarios with Stabilised Moduli · Model 3: An LVS like Supergravity Mediated Model · 0.99
Cites it as support 1 paper
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The resulting soft parameters are unified at a mirage messenger scale hierarchically lower than $M_GUT$, leading to significantly compressed low energy superparticle masses [ref] compared to other mediation schemes such as mSUGRA, gauge mediation and anomaly mediation.
SUSY Breaking at the Tip of Throat and Mirage Mediation · introduction · 0.96
Cites it as background 15 papers
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The mirage mediation is a SUSY breaking mediation mechanism based on supergravity [ref] [ref] [ref] .
TeV scale mirage mediation in NMSSM and precision Higgs measurement · TeV scale mirage mediation in NMSSM · 1.00
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The mirage mediation is one of interesting mediation mechanisms [ref] , and it is a mixture between anomaly mediation and modulus mediation.
NMSSM in TeV scale mirage mediation · Introduction · 0.98
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The phenomenology of this class of models has been heavily studied (see e.g. [ref] ).
Supersymmetry Breaking due to Moduli Stabilization in String Theory · Introduction · 0.98
Discussion
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