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Mu Problem and Hybrid Inflation in Supersymmetric SU(2)_L x SU(2)_R x U(1)_B-L

High Energy Physics - Phenomenology · Submitted 10 Oct 1997 · 19 references

Pith's verdict: The singlet-does-everything construction is genuinely clever and checks out at leading order, but the vacuum selection and the deferred leptogenesis/inflation numbers are thinner than the abstract suggests.

T0 · AI review

How this review was made: An AI referee (selfhosted/deepseek-v4.1-flash) read the paper on November 13, 2026 and answered a fixed list of questions about it. T0 is the starting level every paper gets. The levels describe how deeply Pith has checked the paper, never the authors.

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arXiv IDhep-ph/9710314 (version 1)
Pith ID63CWCOF7, Pith's permanent record of this paper and its review
CitationAristotle Univ.), G. Dvali (CERN), G. Lazarides (CERN, Q. Shafi (Bartol Res. Inst.). "Mu Problem and Hybrid Inflation in Supersymmetric SU(2)_L x SU(2)_R x U(1)_B-L." arXiv:hep-ph/9710314 (1997). https://pith.science/paper/63CWCOF7
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Referee report
The paper

The paper claims

A single singlet field in a left-right supersymmetric model is claimed to generate the MSSM mu parameter, its soft partner B mu, and a flat inflationary potential, all from one superpotential term.

The reading

Supersymmetric extensions of the Standard Model contain a mass parameter called $mu$ that sets the scale of the two Higgs doublets, and nothing in the minimal theory explains why it should sit near the weak scale rather than at the Planck scale. This paper argues that $mu$ need not be an input at all: if the Higgs doublets are pseudo-Goldstone modes of a broken $SU(2)_R times U(1)_{B-L}$ symmetry, supersymmetry breaking shifts the vacuum expectation value of a gauge-singlet field $S$ by an amount of order the gravitino mass, and the coupling $S h^{(1)}h^{(2)}$ then generates both $mu$ and its soft partner $B mu$ automatically. The same singlet, because it enters the superpotential only linearly, yields a flat inflaton potential with constant energy $kappa^2 M^4$, so the mechanism that fixes $mu$ also supplies hybrid inflation. The authors further claim that an unbroken R-symmetry keeps the proton stable and, through leptogenesis fed by the inflaton's oscillations, can produce the observed baryon asymmetry, while right-handed neutrinos at the $SU(2)_R$ breaking scale give eV-scale neutrinos as the hot dark matter component.

What carries the argument

The load-bearing object is the gauge-singlet chiral superfield $S$ that appears in the superpotential only linearly, with an R-charge equal to that of the superpotential itself. Linearity is what makes the argument work in both directions: it guarantees that the inflaton potential is flat at tree level and that the one-loop Coleman-Weinberg correction is the only slope, and it guarantees that $S$ has no self-interactions to stabilize it at zero, so the tadpole proportional to $M^2$ from the soft terms displaces it by an amount fixed by $m_{3/2}$ rather than by $M$. The pseudo-Goldstone character of the Higgs doublets, following from an accidental $U(4)$ symmetry of the potential when $lambda = kappa$, is what keeps the doublets light and makes the generated $mu^2$ and $B mu$ automatically of the same order. The same R-symmetry whose $Z_2$ subgroup is ordinary matter parity also forbids the dimension-five operators that would let the proton decay, and the $l^c$ vev provides seesaw masses for right-handed neutrinos.

Extended reading notes

Core claim

The paper's central claim is that one renormalizable superpotential, $W = S(kappa l^c bar{l}^c + lambda h^2 - kappa M^2)$, does three jobs at once in a supersymmetric $SU(3)_c times SU(2)_L times SU(2)_R times U(1)_{B-L}$ model. First, the singlet $S$ triggers breaking of $SU(2)_R times U(1)_{B-L}$ at a scale $M$ far above the weak scale through the vacuum expectation values of the doublet pair $l^c, bar{l}^c$. Second, after gravity-mediated supersymmetry breaking the tadpole induced by that large vev shifts $S$ away from zero by roughly $-m_{3/2}/kappa$, so that $mu = lambda langle S rangle = -lambda m_{3/2}/kappa$ and $B mu = -2 lambda m_{3/2}^2/kappa$ come out of order the gravitino mass without any fine tuning of $M$; the Higgs doublets are pseudo-Goldstones of an approximate $U(4)$ symmetry of the scalar potential and stay massless until supersymmetry breaking lifts the flat direction. Third, for $|S| > max(M, M sqrt{kappa/lambda})$ all gauge non-singlet fields acquire masses of order $|S|$ and decouple, leaving an effective superpotential $W_{infl} = -kappa S M^2$ linear in $S$, hence a constant tree-level vacuum energy $V_{tree} = kappa^2 M^4$ and a one-loop logarithmic slope $V_{infl} simeq kappa^2 M^4 [1 + ((kappa^2+lambda^2)/8 pi^2) ln(S S^*/Lambda^2)]$ that drives the field to the minimum. Inflation ends when the condition on $|S|$ fails and some field goes tachyonic; the authors prefer $kappa < lambda$ so that the system falls to the $SU(2)_R$-breaking vacuum rather than to the one with large electroweak doublet vevs.

Load-bearing premise

The argument needs the universe to settle in the vacuum with $h = 0$ and $l^c bar{l}^c = M^2$; the paper shows the competing minimum with large electroweak doublet vevs is degenerate with it to leading order and can only be disfavoured by choosing a non-minimal Kaehler parameter with $|alpha|^2 geq lambda/kappa > 1$, justified by the single sentence that cosmological evolution prefers that choice, with no trajectory analysis given.

Editorial extensions

If this is right

  • The MSSM $mu$ parameter stops being a free input: it is predicted as $mu = -lambda m_{3/2}/kappa$, of order the gravitino mass, with $B mu = -2 lambda m_{3/2}^2/kappa$, and the relation $mu^2 + m_{3/2}^2 = -B mu$ holds in the $U(4)$-symmetric limit $lambda = kappa$.
  • The same sector that breaks $SU(2)_R times U(1)_{B-L}$ at scale $M$ is the inflaton sector, so the scale of new physics and the scale of inflation are tied together, with $V = kappa^2 M^4$ during the flat phase.
  • The scalar spectral index comes out extremely close to unity, consistent with a mixed cold-plus-hot dark matter picture in which the hot component is a neutrino in the eV range.
  • Baryogenesis proceeds through leptogenesis: the inflaton oscillations produce right-handed neutrinos whose decays create a lepton asymmetry, partially converted to baryon number by sphalerons, with the reheat temperature compatible with the gravitino bound.
  • Proton decay from dimension-five operators is absent to all orders as long as the R-symmetry is exact in the superpotential, so the proton is essentially stable.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • Because $mu$ is generated by the same shift that sets the inflaton mass scale, a measurement pinning the inflaton coupling $kappa$ and $M$ would indirectly fix the ratio $lambda/kappa$ and hence the size of $B mu$; this cross-link is a testable correlation the paper does not spell out.
  • The requirement $kappa < lambda$ is stated but not derived from the inflationary dynamics; a dedicated slow-roll analysis with the one-loop potential could turn it into a quantitative constraint on the $SU(2)_R$ breaking scale, which the paper only estimates as roughly an order of magnitude below the MSSM unification scale.
  • The eV-scale neutrino hot dark matter component is the most externally checkable element: cosmological bounds on the sum of neutrino masses tighten the allowed window independently of any collider or proton-decay test of the $mu$ mechanism.
  • The mechanism relies on gravity-mediated supersymmetry breaking to set the size of the shift; in a gauge-mediated version the displacement scale would change, so the claim that $mu$ comes out near the weak scale is tied to the mediation scheme rather than to the left-right structure alone.
Original abstract

We present a solution of the mu problem within a supersymmetric model based on the SU(2)_L x SU(2)_R x U(1)_{B-L} gauge group. We show that this solution implies a built-in hybrid inflationary scenario, which may result in a successful baryogenesis via leptogenesis. Baryon number is essentially conserved as a result of an R-symmetry. Neutrinos with mass in the eV range can provide the `hot' dark matter component.

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.

Compiled by classifier-1.13-20260917 via OpenRouter, question bank abstract-p1-20260923, 2026-09-23: 1 request, 3,579 input tokens, $0.0001 reported.

What the abstract itself states, as probabilities: claims first 0.03 · states limitation 0.20 · human participants 0.01 · controlled comparison 0.01 · randomized assignment 0.01 · states quantitative result 0.65 · compares with prior results 0.04 · mentions code or data availability 0.01.

The abstract, sentence by sentence

arXiv listing abstract v1. Results and the main claim are underlined; .

We present a solution of the mu problem within a supersymmetric model based on the SU(2)_L x SU(2)_R x U(1)_{B-L} gauge group. We show that this solution implies a built-in hybrid inflationary scenario, which may result in a successful baryogenesis via leptogenesis. Baryon number is essentially conserved as a result of an R-symmetry. Neutrinos with mass in the eV range can provide the `hot' dark matter component.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#sentencerolethe authors' own workstates the main conclusionstrength
s0 We present a solution of the mu problem within a supersymmetric model based on the SU(2)_L x SU(2)_R x U(1)_{B-L} gauge group. contribution 1.00 0.94 0.46 asserted 1.00
s1 We show that this solution implies a built-in hybrid inflationary scenario, which may result in a successful baryogenesis via leptogenesis. interpretation 0.88 0.89 0.47 hedged possibility 0.63
s2 Baryon number is essentially conserved as a result of an R-symmetry. result 0.94 0.65 0.08 asserted 1.00
s3 Neutrinos with mass in the eV range can provide the `hot' dark matter component. result 0.66 0.42 0.06 hedged possibility 0.73

What kind of paper the classifier reports this is: theoretical result 1.00 · evidence from proof or derivation 0.86.

What was examined, and what was not

sources read
  • arXiv listing abstract v1
not examined
  • full text
  • figures and tables
  • references and citing sentences
  • relations to other papers
levels run
  • P abstract
not run
  • S sections
  • T body sentences
  • C citations
  • R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

References
How the literature uses it

38 arXiv papers cite this in 61 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers whose main result relates to this one's

Found among the papers closest to this one by title and main claim. Pith's classifier compared each pair's main results and a second model family confirmed the relation; checked against two further families, shown conflicts agreed 118 times in 120 and shown same results 218 times in 239. The quoted sentence is the other paper's main claim.

States the same result 1 paper

Papers citing it · 55 sentences without a confident label

Cites it as background 5 papers

Discussion

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