Catalog · Collider RS · CR013

CR013 $pp \to X \to \gamma\gamma; \,\text{high-mass spin-0/spin-2 resonance}\,$

Diphoton high-mass resonance (spin-0/2)

Status REVIEWED VERIFIED High Code: NO Priority Low

PDG / equivalent values

Observable	Value	Year	Experiment / source	Provenance
Lower limit on lightest RS KK graviton mass in pp $ \to G* \to \gamma\gamma$	m_G* > 4.8 TeV 95% CL (lower_limit)	2025	CMS	source ↑
RS graviton mass-exclusion range in pp $ \to G* \to \gamma\gamma$	m_G* below 2.2-5.6 TeV excluded for 0.01 < ktilde < 0.2 95% CL (lower_limit_range)	2024	CMS	source ↑
Lower limit on RS1 graviton mass in pp $ \to G* \to \gamma\gamma$	m_G* > 4.5 TeV for k/M_Pl = 0.1 95% CL (lower_limit)	2021	ATLAS	source ↑
Lower limit on RS1 graviton mass in pp $ \to G* \to \gamma\gamma$	m_G* > 3.9 TeV for k/M_Pl = 0.05 95% CL (lower_limit)	2021	ATLAS	source ↑
Lower limit on RS1 graviton mass in pp $ \to G* \to \gamma\gamma$	m_G* > 2.2 TeV for k/M_Pl = 0.01 95% CL (lower_limit)	2021	ATLAS	source ↑
RS graviton mass-exclusion range in pp $ \to G* \to \gamma\gamma$	m_G* below 2.3-4.6 TeV excluded for ktilde = 0.01-0.2 95% CL (lower_limit_range)	2018	CMS	source ↑
Lower limit on lightest RS graviton mass in pp $ \to G* \to \gamma\gamma$	m_G* > 2.66 TeV for k/M_Pl = 0.1 95% CL (lower_limit)	2015	ATLAS	source ↑

Why this constrains the RS scan

This is a direct collider constraint on a neutral spin-2 resonance with diphoton branching fraction, not a low-energy flavor observable. In a minimal RS1-style benchmark, the quoted bound constrains the lightest graviton excitation $m_{G^*}$ after fixing $k/\bar M_{\rm Pl}$, the production cross section, and the branching fraction to $\gamma\gamma$. It does not directly constrain the KK-gluon mass used in the anarchic-flavor scan unless a specific RS spectrum map and coupling convention are supplied. For the present RS scan, the reach is therefore diagnostic rather than leading. The quark-scan methodology note quotes the live RS-anarchy median crossing $M_{\rm KK}^{\min}(p50,g_* = 3)=47.26~{\rm TeV}$, far above the few-TeV direct diphoton reach. A TeV-scale diphoton resonance bound is still useful as a cross-check on non-anarchic or non-minimal RS scenarios, and it is especially relevant when gravity or scalar sectors are light while flavor protection or alignment weakens the low-energy bounds.

What's changed since the original paper

The post-2010 LHC history is a steady increase in energy, luminosity, and benchmark coverage relative to the original RS graviton phenomenology papers. CMS $7$ TeV diphoton data in arXiv:1112.0688 and ATLAS $7$ TeV diphoton data in arXiv:1210.8389 established the early LHC resonance limits in the $\gamma\gamma$ channel. ATLAS arXiv:1504.05511 used the $8$ TeV diphoton spectrum and raised the $k/\bar M_{\rm Pl}=0.1$ RS-graviton limit to $2.66$ TeV. CMS arXiv:1809.00327 moved to $13$ TeV data and excluded $m_{G^*}$ below $2.3$--$4.6$ TeV for coupling parameters from 0.01 to 0.2. ATLAS arXiv:2102.13405 used $139~{\rm fb}^{-1}$ and excluded the RS1 benchmark below $2.2$, $3.9$, and $4.5$ TeV for $k/\bar M_{\rm Pl}=0.01$, 0.05, and 0.1. CMS arXiv:2405.09320 is the current full-Run-2 CMS update, with $138~{\rm fb}^{-1}$, refined diphoton background treatments, spin-0 and spin-2 resonance interpretations, and the strongest reported RS-graviton diphoton limits for $k/\bar M_{\rm Pl}\ge 0.1$.

Validity and model dependence

The quoted mass exclusions are benchmark exclusions. They assume a production mechanism, a resonance line shape, a width tied to the chosen $k/\bar M_{\rm Pl}$, and the branching pattern of the RS graviton model used by the experiments. They are not model-independent lower bounds on every RS KK mass. In warped models with Standard Model fields propagating in the bulk, the couplings of the KK graviton to $ee$, $\mu\mu$, and $\gamma\gamma$ can be suppressed; the PDG review explicitly warns that the dilepton and diphoton bounds do not apply directly in that case (pdg2025\_extra\_dimensions\_review.txt). Spin-0 diphoton limits are similarly useful only after specifying whether the scalar is a radion, singlet, heavy Higgs-like state, or another resonance with a definite production and branching model.

Code coverage in this repo

NO. Greps over quarkConstraints/, qcd/, flavorConstraints/, neutrinos/, yukawa/, warpConfig/, solvers/, scanParams/, and tests/ found no diphoton, RS-graviton, LHC-resonance, or collider direct-search likelihood implementation. Adjacent evidence is generic only: solvers/bessel.py:5 and solvers/bessel.py:6 solve KK masses for gauge bosons and fermions in RS backgrounds, scanParams/scan.py:399 and scanParams/scan.py:429 compute and record $M_{\rm KK}$, and quarkConstraints/deltaf2.py:1, quarkConstraints/deltaf2.py:459, and quarkConstraints/deltaf2.py:557 implement the low-energy $\Delta F=2$ KK-gluon-inspired exclusion slice. None of those paths evaluates $pp\to G^*\to\gamma\gamma$, cross-section upper limits, or mass-exclusion curves.

Implementation difficulty

HIGH. A live collider constraint would require a model-specific RS spectrum and branching calculator plus a reinterpretation of LHC upper limits, or an external collider-recast workflow such as CheckMATE, MadAnalysis5, Rivet/Contur, or a dedicated simplified-likelihood treatment. The blocker is not data availability; it is the translation from a 5D point to production rates, branching ratios, widths, acceptances, and experimental likelihoods.

Reason: A live CR013 constraint needs a spectrum/branching model plus collider reinterpretation of cross-section upper limits or a full recast/likelihood workflow; the repo currently has no collider direct-search machinery.

Key references

PDG2025\_ExtraDimensionsListing; PDG2025\_ExtraDimensionsReview; CMS2024\_Diphoton\_ArxivFullText; CMS2024\_Diphoton\_PublicPage; CMS2024\_Diphoton\_HEPData; ATLAS2021\_Diphoton\_ArxivFullText; CMS2018\_Diphoton\_ArxivFullText; ATLAS2015\_Diphoton\_ArxivFullText; RandallSundrum1999; DavoudiaslHewettRizzo1999.

display m_G* > 4.8 TeV

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Match 1 of 2 snapshot line 218

L215:    limits on MD for two to six extra dimensions (see their Fig. 18).
L216:  9 AAD 13C search for p p → γ G , using 4.6 fb−1 of data at √s = 7 TeV to place bounds
L217:    on MD for two to six extra dimensions, from which this bound on R is derived.
L218: 10 AAD 13D search for the dijet decay of quantum black holes in 4.8 fb−1 of data produced
L219:                        √
L220:    in p p collisions at s = 7 TeV to place bounds on MD for two to seven extra dimensions,
L221:    from which these bounds on R are derived. Limits on MD for all δ ≤ 7 are given in

Match 2 of 2 snapshot line 566

L563:      Citation: S. Navas et al. (Particle Data Group), Phys. Rev. D 110, 030001 (2024) and 2025 update
L564: 
L565: 
L566:  12 AAD 12CP use diphoton events with large missing transverse momentum in 4.8 fb−1
L567:                                                 √
L568:     of data produced from p p collisions at s = 7 TeV to place a lower bound on the
L569:     compactiﬁcation scale in a universal extra dimension model with gravitational decays.

display m_G* below 2.2-5.6 TeV excluded for 0.01 < ktilde < 0.2

RESOLVED

Match snapshot line 595

L592: 	</tr>
L593: 
L594: 	<tr><td colspan=1 class="textline">
L595: <!-- _SUMMARY_ -->A search has been performed for new physics in high-mass diphoton events from proton-proton collisions at a center-of-mass energy of 13 TeV. The data used correspond to an integrated luminosity of 138 fb$ ^{-1} $ collected with the CMS detector in 2016-2018. No statistically significant excess, either resonant or nonresonant, is observed in the spectra. Masses below 2.2 to 5.6 TeV are excluded at the 95% confidence level for the excited state of the Randall-Sundrum (RS) graviton, for coupling parameters between 0.01 $ < \tilde{k} < $ 0.2. Limits are also set on the production of scalar Higgs boson like resonances. In the model with large extra spatial dimensions by Arkani-Hamed, Dimopoulos, and Dvali (ADD), exclusion limits on the mass scale $ M_{\mathrm{S}} $ range between 7.1 to 11.1 TeV, depending on the specific convention. Additionally, exclusion limits are set in the two-dimensional space of the continuum clockwork model, with the fundamental scale $ M_{5} $ excluded at the 95% confidence level below 8.0 TeV for $ k $ values between 0.2 GeV and 2.0 TeV. The present results are the strongest limits to date on ADD extra dimensions and RS gravitons with $ \tilde{k} \ge $ 0.1.
L596: 	</td></tr>
L597: 
L598:       </table>

display m_G* > 4.5 TeV for k/M_Pl = 0.1

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Match snapshot line 478

L475: 
L476: 
L477: to Ref. [11] comes from the increased integrated luminosity. The RS1 model is excluded for 𝑚 𝐺 ∗ below
L478: 2.2, 3.9 and 4.5 TeV for 𝑘/𝑀 Pl values of 0.01, 0.05 and 0.1, respectively.
L479: 
L480: 
L481:

display m_G* > 3.9 TeV for k/M_Pl = 0.05

RESOLVED

Match snapshot line 478

L475: 
L476: 
L477: to Ref. [11] comes from the increased integrated luminosity. The RS1 model is excluded for 𝑚 𝐺 ∗ below
L478: 2.2, 3.9 and 4.5 TeV for 𝑘/𝑀 Pl values of 0.01, 0.05 and 0.1, respectively.
L479: 
L480: 
L481:

value_limit_fallback > 2.2 TeV

RESOLVED

Match snapshot line 478

L475: 
L476: 
L477: to Ref. [11] comes from the increased integrated luminosity. The RS1 model is excluded for 𝑚 𝐺 ∗ below
L478: 2.2, 3.9 and 4.5 TeV for 𝑘/𝑀 Pl values of 0.01, 0.05 and 0.1, respectively.
L479: 
L480: 
L481:

display m_G* below 2.3-4.6 TeV excluded for ktilde = 0.01-0.2

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Match 1 of 3 snapshot line 36

L33:                                              to an integrated luminosity of 35.9 fb−1 . The search is performed for both resonant
L34:                                              and nonresonant new physics signatures. At 95% confidence level, lower limits on
L35:                                              the mass of the first Kaluza–Klein excitation of the graviton in the Randall–Sundrum
L36:                                              warped extra-dimensional model are determined to be in the range of 2.3 to 4.6 TeV,
L37:                                              for values of the associated coupling parameter between 0.01 and 0.2. Lower limits
L38:                                              on the production of scalar resonances and model-independent cross section upper
L39:                                              limits are also provided. For the large extra-dimensional model of Arkani-Hamed,

Match 2 of 3 snapshot line 653

L650: Asymptotic formulas [55] are used in the calculations of limits.
L651: Expected and observed upper limits at 95% confidence level (CL) on the production of scalar
L652: and RS graviton resonances are shown in Fig. 3. Using leading order cross sections from
L653: PYTHIA , RS gravitons with masses mX below 2.3, 4.1, and 4.6 TeV can be excluded for k̃ = 0.01,
L654: 0.1, and 0.2, respectively, corresponding to ΓX /mX = 1.4 × 10−4 , 1.4 × 10−2 , and 5.6 × 10−2 ,
L655: respectively.
L656: Limits can also be set, in a model independent fashion, on the cross sections for events in

Match 3 of 3 snapshot line 1109

L1106: signature of large extra dimensions, in the scenario by Arkani-Hamed, Dimopoulos, and Dvali,
L1107: or a continuum clockwork model.
L1108: The data are found to be in agreement with the predicted background from standard model
L1109: sources, and no evidence for new physics is seen. Masses below 2.3–4.6 TeV are excluded at
L1110: 95% confidence level for the excited state of the Randall–Sundrum graviton, for a coupling pa-
L1111: rameter in the range 0.01 < k̃ < 0.2. Limits are also set on the production of scalar resonances,
L1112: and model-independent cross section limits have been extracted as a function of diphoton in-

display m_G* > 2.66 TeV for k/M_Pl = 0.1

AMBIGUOUS

Match 1 of 2 snapshot line 28

L25:                                                  the Large Hadron Collider. The data are found to be in agreement with the Standard Model
L26:                                                  prediction, and limits are reported in the framework of the Randall-Sundrum model. This
L27:                                                  theory leads to the prediction of graviton states, the lightest of which could be observed at
L28:                                                  the Large Hadron Collider. A lower limit of 2.66 (1.41) TeV at 95% confidence level is set
L29:                                                  on the mass of the lightest graviton for couplings of k/M Pl = 0.1 (0.01).
L30: 
L31:

Match 2 of 2 snapshot line 682

L679: are derived from the limits on σ × BR(G∗ → γγ). The only free parameters of this model are the mass
L680: of the lightest graviton (mG∗ ) and the coupling to the SM fields (k/M Pl ), i.e. σ × BR(G∗ → γγ) can be
L681: calculated once the values of these two parameters are specified. The limits can therefore be expressed
L682: in terms of mG∗ for a given value of k/M Pl . A lower limit of 2.66 (1.41) TeV at 95% confidence level is
L683: obtained on the mass of the lightest graviton for a coupling k/M Pl = 0.1 (0.01). The results reported in
L684:                                                                                           √
L685: this article constitute a significant improvement over the results in Ref. [5] obtained at s = 7 TeV. The