HEPData Search

A search for new physics in events featuring a single photon and missing transverse momentum is presented, using proton-proton $\sqrt{s}$ = 13 TeV collision data corresponding to an integrated luminosity of 101 fb$^{-1}$ collected by the CMS experiment at the CERN LHC between 2017 and 2018. This analysis, combined with a previous study of 36 fb$^{-1}$ of 2016 data (totaling 137 fb$^{-1}$), reveals no significant deviations from standard model expectations. The results are then used to establish 95% confidence level limits on parameters in theoretical models involving dark matter and large extra dimensions. Compared to the 2016-only analysis, this search achieves up to a 14% improvement in exclusion reach for mediator masses in simplified dark matter models, along with 11% and 1% enhancements in the limits on the effective field theory suppression scale and the fundamental Planck scale, respectively. These results are the most stringent constraints on these parameters to date.

39 data tables

Figure 2 left

Distribution of ET /pmiss for the 2017 data sets.

Figure 2 right

Distribution of ET /pmiss for the 2018 data sets.

Figure 3 left

Distribution of ∆φ(pmiss, pT ) for the 2017 data sets.

Figure 3 right

Distribution of ∆φ(pmiss, pT ) for the 2018 data sets.

Figure 4 left

Comparison of data and background post-fit distributions in the eν + γ CRs for the combination of 2017 and 2018 data sets. The last bin of the distribution includes the overflow events. The ratios of data to the background predictions are shown in the lower panels, with the uncertainty bands including the combination of all systematic uncertainties.

Figure 4 right

Comparison of data and background post-fit distributions in the μν +γ CRs for the combination of 2017 and 2018 data sets. The last bin of the distribution includes the overflow events. The ratios of data to the background predictions are shown in the lower panels, with the uncertainty bands including the combination of all systematic uncertainties.

Figure 5 left

Comparison of data and background post-fit distributions in the ee + γ CRs for the combination of 2017 and 2018 data sets. The last bin of the distribution includes the overflow events. The ratios of data to the background predictions are shown in the lower panels, with the uncertainty bands including the combination of all systematic uncertainties.

Figure 5 right

Comparison of data and background post-fit distributions in the μμ + γ CRs for the combination of 2017 and 2018 data sets. The last bin of the distribution includes the overflow events. The ratios of data to the background predictions are shown in the lower panels, with the uncertainty bands including the combination of all systematic uncertainties.

Figure 6 left

Comparison of data and background post-fit distributions for the vertical regions for the combination of 2017 and 2018 data sets.

Figure 6 right

Comparison of data and background post-fit distributions for the horizontal regions for the combination of 2017 and 2018 data sets.

Figure 7 left

The ratio of 95% CL upper cross section limits to the theoretical cross section (μ95) for simplified DM models with vector mediators, using the full 2016–2018 data set.

Figure 7 left expected limit curve

The ratio of 95% CL upper cross section limits to the theoretical cross section (μ95) for simplified DM models with vector mediators, using the full 2016–2018 data set.

Figure 7 left observed limit curve

The ratio of 95% CL upper cross section limits to the theoretical cross section (μ95) for simplified DM models with vector mediators, using the full 2016–2018 data set.

Figure 7 Lower left

Relic density data for Vector mediator used in Figure 7.

Figure 7 CMS right

The ratio of 95% CL upper cross section limits to the theoretical cross section (μ95) for simplified DM models with Axial vector mediators, using the full 2016–2018 data set.

Figure 7 right expected limit curve for Axial Vector

The ratio of 95% CL upper cross section limits to the theoretical cross section (μ95) for simplified DM models with Axial vector mediators, using the full 2016–2018 data set.

Figure 7 right observed limit curve for Axial Vector

The ratio of 95% CL upper cross section limits to the theoretical cross section (μ95) for simplified DM models with Axial vector mediators, using the full 2016–2018 data set.

Figure 7 relic Lower right

Relic density data for Axial Vector mediator used in Figure 7.

Figure 7 relic Upper right

Relic density data for Axial Vector mediator used in Figure 7.

Figure 8 (CMS)

The 90% CL exclusion limits on the $\chi$--nucleon spin-independent (left) scattering cross sections involving vector operators, respectively, are shown as a function of $m_{\rm DM}$, using the 2016--2018 data set. Simplified model DM parameters $g_q = 0.25$ and $g_{\rm DM} = 1$ are assumed.

Figure 8 (CDMS)

The 90% CL data from CDMS lite experiment used in Figure 8.

Figure 8 (LZ)

The 90% CL data from LZ experiment used in Figure 8.

Figure 8 (panda)

The 90% CL data from Panda experiment used in Figure 8.

Figure 8 (CRESST-II)

The 90% CL data from CRESST experiment used in Figure 8.

Figure 8 (XENONnT 2023)

The 90% CL data from XENONnT 2023 experiment used in Figure 8.

Figure 8 right (CMS)

The 90% CL exclusion limits on the $\chi$--nucleon spin-dependent scattering cross sections involving Axial vector operators are shown as a function of $m_{\rm DM}$, using the 2016--2018 data set. Simplified model DM parameters $g_q = 0.25$ and $g_{\rm DM} = 1$ are assumed.

Figure 8 (PICO)

The 90% CL data from PICO experiment used in Figure 8 (right).

Figure 8 (PICASSO)

The 90% CL data from PICASSO experiment used in Figure 8 (right).

Figure 8 (KAMIOKADE)

The 90% CL data from Kamiokade experiment used in Figure 8 (right).

Figure 8 (Icecube)

The 90% CL data from Icecube experiment used in Figure 8 (right).

Limits on Suppression Scale

Observed and expected 95% CL limits on Suppression Scale as a function of M_{DM}, including ±1σ and ±2σ uncertainty bands.

Figure 10a

The 95% \CL\ observed and expected cross-section limits with ±1σ and ±2σ uncertainty bands as a function of $M_D$.

Figure 10b

Leading-order theoretical cross-section prediction as a function of $M_D$.

Figure 11

The 95% \CL\ upper limits on the ADD graviton production cross section as a function of \mD, for $n=3$ extra dimensions.

Acceptance Efficiency Table for ADD model

Acceptance × Efficiency for ADD models with varying fundamental Planck scale (M_D) and number of extra dimensions (d). This auxiliary material is not shown in any figure or table but is provided for reproducibility and reinterpretation purposes.

Acceptance Efficiency Table for DM-EW model

Acceptance × Efficiency for DM-EW models with varying dark matter mass.

Acceptance Efficiency Table for DM vector Simplified model

Acceptance × Efficiency for DM simplified model for vector mediator.

Acceptance Efficiency Table for DM Axial vector Simplified model

Acceptance × Efficiency for DM simplified model for Axial vector mediator.

Cutflow Table for some signal points

Cut flow for some signal points.

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