Differential cross sections have been measured for nucleon-isobar production and elastic scattering in p−p interactions from 6.2 to 29.7 GeVc in the laboratory angle range 8<θsc<265 mrad. N*' s at 1236, 1410, 1500, 1690, and 2190 MeV were observed. Computer fits to the mass spectra under varying assumptions of resonance and background shapes show that conclusions on t and s dependence are only slightly affected despite typical variations in absolute normalization of ± 35%. Logarithmic t slopes in the small- |t| range are ∼15 (GeVc)−2 for the N*(1410), ∼5 (GeVc)−2 for the N*'s at 1500, 1690, and 2190 MeV, and ∼9 (GeVc)−2 for elastic scattering. Also for the small- |t| data, cross sections for N*'s at 1410, 1500, 1690, and 2190 MeV and for elastic scattering vary only slightly with Pinc consistent with the dominance of Pomeranchuk exchange and with diffraction dissociation. A fit of N*(1690) total cross sections to the form σ∝P−n gives n=0.34±0.06, while for elastic scattering n=0.20±0.05. For the N*(1690) the effective Regge trajectory has the slope αeff′(0)=0.38±0.17. When compared with N* production in π−, K−, and p¯ beams these data also agree with approximate factorization of the Pomeranchuk trajectory. N*(1236) cross sections are consistent with other measurements at similar momenta. For −t>1 (GeVc)−2, elastic scattering cross sections decrease approximately as Pinc−2, and they and N*(1500)− and N*(1690)− production cross sections have t slopes consistent with 1.6 (GeVc)−2.
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We have measured the magnetic moments of the Σ+ and Σ¯ − hyperons produced by 800-GeV protons incident on a Cu target. We determine the Σ+ magnetic moment to be (2.4613±0.0034±0.0040)μN where the uncertainties are statistical and systematic, respectively. In this first measurement we determine the magnetic moment of the Σ¯ − to be -(2.428±0.036±0.007)μN. The magnetic moments of the Σ+ and Σ¯ − are consistent with each other in magnitude but opposite in sign as required by CPT invariance.
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We have mesured the polarization of 375-GeV/c Σ+ and Σ¯ − hyperons produced by 800-GeV/c protons incident on a Cu target. We find that the Σ+ polarization rises with increasing pt to a maximum of 16% at pt=1.0 GeV/c and then decreases to 10% at pt=1.8 GeV/c. We compare this Σ+ polarization with data at lower energies. The Σ¯ − polarization has been measured for the first time. It has the same sign as the Σ+ but smaller magnitude in a similar kinematical region.
Data from Horizontal targeting.
Data from Vertical targeting.
Data from Horizontal targeting.
We have measured the branching ratio for the hyperon radiative decay Ξ−→Σ−γ from a sample of 211±33 events obtained in the polarized 375 GeV/c charged hyperon beam at Fermilab. We find B(Ξ−→Σ−γ/Ξ−→Λ0π−)=(1.22±0.23±0.06)×10−4 where the quoted errors are statistical and systematic, respectively. We have also obtained an indication that the sign of the asymmetry parameter of this decay is positive.
Polarized 375 GeV charged hyperon beam at Fermilab. Sample of 211 +- 33 events.
We utilize the angle and momentum resolution of our apparatus to study the polarization of 375 GeV/c Σ+ hyperons produced by 800 GeV/c protons incident on a Cu target. By examining in detail two of our high statistics data samples, we find evidence for structure in the pt dependence of Σ+ polarization and are able to extract the xF dependence of the Σ+ polarization and compare it with xF behavior in the Λ0 and Ξ− systems.
0.9 mrad horizontal sample.
2.9 mrad horizontal sample.
3.3 mrad horizontal sample.
From measurements of proton-proton elastic scattering at very small momentum transfers where the nuclear and Coulomb amplitudes interfere, we have deduced values of ρ, the ratio of the real to the imaginary forward nuclear amplitude, for energies from 50 to 400 GeV. We find that ρ increases from -0.157 ± 0.012 at 51.5 GeV to +0.039 ± 0.012 at 393 GeV, crossing zero at 280 ± 60 GeV.
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Measurements of energy weighted angular correlations in electron positron annihilations at c.m. energies of 22 GeV and 34 GeV are presented.
ENERGY-ENERGY CORRELATIONS FOR FINAL STATE PARTICLES.
ENERGY-ENERGY CORRELATIONS FOR PRIMORDIAL HADRONS.
ASSYMETRY IN ENERGY CORRELATIONS FOR FINAL STATE PARTICLES.
The differential cross sections for neutron-proton elastic charge-exchange scattering have been measured with a two-arm technique for incident neutron momenta between 22 and 65 GeV/ c and for values of the momentum transfer squared between 0.002 and 0.8 (GeV/ c ) 2 . The sharp forward peak observed previously at lower energies is also present at momenta up to 65 GeV/ c ; however the s dependence of the cross section is slowing down.
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The first search for narrow resonances decaying to three well-separated hadronic jets is presented. The search uses proton-proton collision data corresponding to an integrated luminosity of 138 fb$^{-1}$ at $\sqrt{s}$ = 13 TeV, collected at the CERN LHC. No significant deviations from the background predictions are observed between 1.75-9.00 TeV. The results provide the first mass limits on a right-handed boson Z$_{\mathrm{R}}$ decaying to three gluons, an excited quark decaying via a vector boson to three quarks, as well as updated limits on a Kaluza-Klein gluon decaying via a radion to three gluons.
Observed and expected (background-only fitted) invariant mass spectra of trijet events. Data spectra from three years are fitted separately and the sum is shown in the figure. The fitting function used is ${ d N}/{ d m} = p_{0}(1-x)^{p_{1}}/x^{\sum_{i=2}^{3} p_{i}\log^{i-2}(x)}$. The fitted parameters are $p_{1} = 7.350, p_{2} = 6.926, p_{3} = 0.388$ for 2016, $p_{1} = 8.308, p_{2} = 5.931, p_{3} = 0.167$ for 2017 and $p_{1} = 8.770, p_{2} = 5.617, p_{3} = 0.106$ for 2018. $p_{0}$ is the normalization parameter and its exact value is irrelevant.
Expected and observed limits at 95% CL on $\sigma \mathcal{B} (X \to ggg) \mathcal{A}$ for a 3-body decay trijet resonance with $\Gamma_{X}\sim 3\% m_{X}$. The acceptance $\mathcal{A}$ is defined as $\mathcal{A} = N$(events with $m_{X}^{GEN} > 85\% m_{X}^{input}$) / $N$(events generated in the full phase space defined by the CMS default generator settings). Only 2016 data are used to derive limits below 2.0 TeV because of higher trigger thresholds in 2017 and 2018. Theoretical predictions assuming SM-like couplings are depicted with the red curve.
Expected and observed limits at 95% CL on $\sigma \mathcal{B} (X \to ggg) \mathcal{A}$ for a 3-body decay trijet resonance with $\Gamma_{X}\sim 0.01\% m_{X}$. The acceptance $\mathcal{A}$ is defined as $\mathcal{A} = N$(events with $m_{X}^{GEN} > 85\% m_{X}^{input}$) / $N$(events generated in the full phase space defined by the CMS default generator settings). Only 2016 data are used to derive limits below 2.0 TeV because of higher trigger thresholds in 2017 and 2018. Theoretical predictions are depicted with the red curve.
A search is performed for charged-lepton flavor violating processes in top quark (t) production and decay. The data were collected by the CMS experiment from proton-proton collisions at a center-of-mass energy of 13 TeV and correspond to an integrated luminosity of 138 fb$^{-1}$. The selected events are required to contain one opposite-sign electron-muon pair, a third charged lepton (electron or muon), and at least one jet of which no more than one is associated with a bottom quark. Boosted decision trees are used to distinguish signal from background, exploiting differences in the kinematics of the final states particles. The data are consistent with the standard model expectation. Upper limits at 95% confidence level are placed in the context of effective field theory on the Wilson coefficients, which range between 0.024-0.424 TeV$^{-2}$ depending on the flavor of the associated light quark and the Lorentz structure of the interaction. These limits are converted to upper limits on branching fractions involving up (charm) quarks, t$\to$e$\mu$u (t$\to$e$\mu$c), of 0.032 (0.498)$\times$10$^{-6}$, 0.022 (0.369)$\times$10$^{-6}$, and 0.012 (0.216)$\times$10$^{-6}$ for tensor-like, vector-like, and scalar-like interactions, respectively.
The expected and observed upper limits on CLFV Wilson coefficients. The Limits on the Wilson coefficients are extracted from the upper limits on the cross sections.
The expected and observed upper limits on top quark CLFV branching fractions. The Limits on the top quark CLFV branching fractions are extracted from the upper limits on the Wilson coefficients.