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A brief review of R-parity-violating couplings

High Energy Physics - Phenomenology · Submitted 18 Sep 1997 · 28 references

Pith's verdict: A genuinely useful, honestly sourced 1997 compilation of RPV limits, but the tables are one-coupling-at-a-time slices at m̃ = 100 GeV and the §3 summary should say so.

T0 · AI review

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  4. T3 Formal statement The claims written out in a formal math language a computer can read.
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arXiv IDhep-ph/9709395 (version 2)
Pith IDGRXSZLWO, Pith's permanent record of this paper and its review
CitationGautam Bhattacharyya. "A brief review of R-parity-violating couplings." arXiv:hep-ph/9709395 (1997). https://pith.science/paper/GRXSZLWO
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Referee report
The paper

The paper claims

This review collects the tightest indirect upper bounds on all 45 R-parity-violating Yukawa couplings of supersymmetry, quoted at one sigma for a 100 GeV sfermion mass, with several entries recomputed from 1997 data.

The reading

Supersymmetry pairs every Standard Model particle with a heavier partner, and a discrete bookkeeping rule called R-parity is what normally keeps the two worlds from mixing. If that rule is not exact, new Yukawa couplings appear that let a single superparticle decay into ordinary matter, and the question becomes how large they can be without contradicting data already in hand. This review answers that by walking through every low-energy probe sensitive to such a coupling — proton decay, neutron–antineutron oscillation, neutrino mass, neutrinoless double $\beta$ decay, lepton and quark universality in weak decays, atomic parity violation, neutrino scattering, kaon and D decays, and the LEP lineshape — computing each as a function of one coupling at a time and converting the measured agreement with the Standard Model into an upper limit. The output is a compact set of tables covering all 45 couplings, with the tightest entries reaching $10^{-6}$ and below and the loosest sitting near $0.5$. The point of the exercise is a map of where new physics could still hide: a coupling outside these ranges would have left a trace in data taken long before any collider search for supersymmetry.

What carries the argument

The machinery is the R-parity-violating superpotential itself, $W = 2^{-1}L_iL_jE^c_k + L_iQ_jD^c_k + U^c_iD^c_jD^c_k + L_iH_u$, and the fact that a single coupling of this kind can be rewritten, by a Fierz transformation or a loop calculation, into the same $(V-A)otimes(V-A)$ form as an ordinary weak amplitude. That is what makes the bounds possible: because the new amplitude and the Standard Model amplitude add coherently, each observable becomes a polynomial in one coupling, and the measured agreement with the Standard Model becomes an interval for that coupling. The paper's contribution is the systematic application of this translation to roughly a dozen observables and the assembly of the results into a single indexed table.

Extended reading notes

Core claim

The paper's claim is that its Tables 1 and 2 are the best indirect upper bounds available at the time on the 45 R-parity-violating Yukawa couplings — 27 of the $L$-violating $LQD^c$ type, 9 of the $LLE^c$ type, and 9 of the $B$-violating $U^cD^cD^c$ type — all at one $\sigma$ and for a common sfermion mass of 100 GeV, with the LEP and tau-decay entries recomputed from the 1997 data. The representative numbers are concrete: $|V_{ud}|$ universality and atomic parity violation pin $LQD^c$-type couplings with first-generation indices to the few-percent level, with $0.035$ for the atomic-parity-violation entry; neutrinoless double $\beta$ decay forces the purely first-generation coupling to $0.00035$; the electron-neutrino Majorana mass forces the third-generation $LLE^c$ coupling to $0.003$; double nucleon decay forces the baryon-violating coupling to $10^{-6}$ or below; and the LEP hadronic-to-leptonic ratio, with the top quark running in a triangle loop, bounds the third-generation couplings at $0.34$ to $0.50$. Product couplings fare far worse: proton stability requires $10^{-22}$ for the light-generation combination and $10^{-10}$ for any flavour combination, and kaon mixing requires $10^{-9}$. If the compilation is right, no R-parity-violating coupling outside these ranges survives the low-energy data then available.

Load-bearing premise

Every bound in the tables assumes that exactly one R-parity-violating coupling is nonzero at a time and that all sfermions sit at a common 100 GeV, so the numbers describe a one-dimensional slice of the allowed region rather than its full shape.

Editorial extensions

If this is right

  • Any coupling whose product would mediate proton decay is forced below $10^{-22}$ for light generations and $10^{-10}$ for any flavour combination, so baryon-number violation in supersymmetry must be either absent or extraordinarily weak.
  • The couplings with first-generation quark and lepton indices, which are exactly the ones invoked to explain the large-$Q^2$ HERA anomaly, are pushed to about $0.035$ or below by atomic parity violation, leaving little room for that explanation.
  • Couplings carrying third-generation indices are the least constrained, at $0.34$ to $0.50$, because their leading loop diagrams require top quarks and so their effects are comparatively small.
  • Because every entry is quoted at a common 100 GeV sfermion mass, a heavier superpartner sector weakens all the bounds, so the table should be read as the boundary of the allowed region for light supersymmetry rather than as a mass-independent statement.

Reading between the lines

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

  • Every observable here is quadratic in the coupling, so a table of one-coupling-at-a-time limits does not by itself bound the case where two couplings are simultaneously comparable; a dedicated flat-direction analysis would be needed to close that gap, and the paper does not attempt one.
  • The author marks the kaon-decay and $D^0$–$\bar D^0$ entries as basis-dependent, which means the two numbers $0.012$ and $0.20$ are not physical quantities but artefacts of assuming the CKM matrix equals one or the other of the two mixing rotations; a basis-independent formulation would be the statement worth carrying forward.
  • The third-generation entries are set by LEP lineshape precision, so the same observables at a future $Z$ factory would tighten them roughly with the square root of the collected statistics — a straightforward experimental upgrade path the review does not spell out.
  • Since the bounds scale with the assumed sfermion mass, a supersymmetric spectrum heavy enough to evade direct searches would relax the whole table, which means the strongest entries are conditional on light superpartners rather than on the R-parity-violating idea itself.
Original abstract

I review the upper limits on the R-parity-violating Yukawa couplings from indirect searches. Some limits have been updated using recent data.

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, 2,176 input tokens, $0.0001 reported.

What the abstract itself states, as probabilities: claims first 0.02 · states limitation 0.12 · human participants 0.02 · controlled comparison 0.03 · randomized assignment 0.01 · states quantitative result 0.08 · compares with prior results 0.33 · mentions code or data availability 0.02.

The abstract, sentence by sentence

arXiv listing abstract v2. Results and the main claim are underlined; .

I review the upper limits on the R-parity-violating Yukawa couplings from indirect searches. Some limits have been updated using recent data.

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 I review the upper limits on the R-parity-violating Yukawa couplings from indirect searches. contribution 0.98 0.37 0.19 asserted 0.78
s1 Some limits have been updated using recent data. contribution 0.82 0.42 0.10 asserted 1.00

What kind of paper the classifier reports this is: review 1.00 · evidence from literature 0.87.

What was examined, and what was not

sources read
  • arXiv listing abstract v2
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

39 arXiv papers cite this in 48 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 citing it · 21 sentences without a confident label

Uses its data or values 2 papers
Compares with it 1 paper
Cites it as background 23 papers

Discussion

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