2025-05-26
20:27 |
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2025-05-25
11:31 |
Observation of $4\ell\gamma$ and evidence of $\mathrm ZZ\gamma$ production in proton-proton collisions at $\sqrt{s}$ = 13 TeV
/CMS Collaboration
The first measurement of the production cross section of four charged leptons and a photon in proton-proton collisions is presented.
The analysis utilises data collected by the CMS experiment from 2016 to 2018 at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb$^{-1}$.
The observed (expected) significance for the observation of $\mathrm{pp} \rightarrow 4\ell \gamma$ in a phase space with $p_\mathrm{T}^\gamma > 20~\mathrm{GeV}$, $|\eta^\gamma| < 2.4$ and $\Delta R(\ell,\gamma) > 0.5$ is 5.1 (4.1) standard deviations.
The measured and expected fiducial cross sections are $\left(0.16 \pm 0.06 \right)~\mathrm{fb}$ and $\left(0.10 \pm 0.03 \right)~\mathrm{fb}$ respectively.
The $4\ell\gamma$ events, with the additional requirement that the invariant mass of any of the two lepton pairs and the photon is greater than $100~\mathrm{GeV}$, are also used to search for the production of the triboson process, $\mathrm{pp} \rightarrow \mathrm{ZZ}\gamma$, with fully leptonic decays of the Z bosons, leading to the first evidence for this process, with an observed (expected) significance of 3.7 (3.0) standard deviations.
The measured and expected fiducial cross sections for $\mathrm{pp} \rightarrow \mathrm{ZZ}\gamma \rightarrow 4\ell \gamma$ are $\left(0.06 \pm 0.03 \right)$ fb and $\left(0.04 \pm 0.02 \right)$ fb, respectively.
Both results are in agreement with the standard model prediction within one standard deviation..
CMS-PAS-SMP-24-014.-
Geneva : CERN, 2025
Figure_001-a: PDF; Figure_001-b: PDF; Figure_002-a: PDF; Figure_002-b: PDF; Figure_003: PDF; Figure_004: PDF; Fulltext in PDF: PDF; External link: Additional information for the analysis (restricted access)
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2025-05-21
22:03 |
First fully exclusive reconstruction of radiative decays of the $\mathrm{B}^{*+}$, $\mathrm{B}^{*0}$, and $\mathrm{B}^{*0}_\mathrm{s}$ mesons and measurement of their masses in proton-proton collisions at $\sqrt{s} = 13\,\text{TeV}$
/CMS Collaboration
Using a data sample corresponding to an integrated luminosity of $140\,\text{fb}^{-1}$ of proton-proton collisions collected by the CMS experiment at $\sqrt{s}= 13\,\text{TeV}$ in 2016--2018, the first full reconstruction of the three vector B meson states, $\mathrm{B}^{*+}$, $\mathrm{B}^{*0}$, and $\mathrm{B}^{*0}_\mathrm{s}$, is performed. The mass differences between the excited mesons and their corresponding ground states are measured to be $m(\mathrm{B}^{*+})-m(\mathrm{B}^{+}) = 45.277\pm0.039\pm0.021\,\text{MeV}$, $m(\mathrm{B}^{*0})-m(\mathrm{B}^{0}) = 45.471\pm0.056\pm0.024\,\text{MeV}$, and $m(\mathrm{B}^{*0}_\mathrm{s})-m(\mathrm{B}^{0}_\mathrm{s}) = 49.407\pm0.132\pm0.034\,\text{MeV}$, where the first uncertainty is statistical and the second is systematic. [...]
CMS-PAS-BPH-24-011.-
Geneva : CERN, 2025
Figure_001-a: PDF; Figure_001-b: PDF; Figure_001-c: PDF; Figure_A001-d: PDF; Figure_A001-e: PDF; Figure_A001-f: PDF; Figure_A001-g: PDF; Figure_C001-h: PDF; Figure_C001-i: PDF; Fulltext in PDF: PDF; External link: Additional information for the analysis (restricted access)
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2025-05-21
11:48 |
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2025-05-21
10:09 |
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2025-05-20
09:33 |
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2025-05-19
17:11 |
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2025-05-18
10:54 |
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2025-05-17
15:32 |
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2025-05-16
11:28 |
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