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Register a new userFirst measurement of the total proton-proton cross section at the LHC energy of {surd} s =7 TeV
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TOTEM has measured the differential cross-section for elastic proton-proton scattering at the LHC energy of {srud}s = 7TeV analysing data from a short run with dedicated large {beta} * optics. A single exponential fit with a slope B = (20:1{pm}0:2stat {pm}0:3syst)GeV-2 describes the range of the four-momentum transfer squared |t| from 0.02 to 0.33 GeV2. After the extrapolation to |t| = 0, a total elastic scattering cross-section of (24:8{pm}0:2stat {pm}1:2syst) mb was obtained. Applying the optical theorem and using the luminosity measurement from CMS, a total proton-proton cross-section of (98:3{pm}0:2stat {pm}2:8syst) mb was deduced which is in good agreement with the expectation from the overall fit of previously measured data over a large range of center-of-mass energies. From the total and elastic pp cross-section measurements, an inelastic pp cross-section of (73:5{pm}0:6stat +1:8 -1:3 syst) mb was inferred. PACS 13.60.Hb: Total and inclusive cross sections
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Proton-proton elastic scattering has been measured by the TOTEM experiment at the CERN Large Hadron Collider at {surd}s = 7 TeV in dedicated runs with the Roman Pot detectors placed as close as seven times the transverse beam size (sbeam) from the outgoing beams. After careful study of the accelerator optics and the detector alignment, |t|, the square of four-momentum transferred in the elastic scattering process, has been determined with an uncertainty of d t = 0.1GeV p|t|. In this letter, first results of the differential cross section are presented covering a |t|-range from 0.36 to 2.5GeV2. The differential cross-section in the range 0.36 < |t| < 0.47 GeV2 is described by an exponential with a slope parameter B = (23.6{pm}0.5stat {pm}0.4syst)GeV-2, followed by a significant diffractive minimum at |t| = (0.53{pm}0.01stat{pm}0.01syst)GeV2. For |t|-values larger than ~ 1.5GeV2, the cross-section exhibits a power law behaviour with an exponent of -7.8_pm} 0.3stat{pm}0.1syst. When compared to predictions based on the different available models, the data show a strong discriminative power despite the small t-range covered.
The production cross-sections of B mesons are measured in pp collisions at a centre-of-mass energy of 7 TeV, using data collected with the LHCb detector corresponding to a integrated luminosity of 0.36 fb-1. The B+, B0 and Bs0 mesons are reconstructed in the exclusive decays B+ -> J/psi K+, B0 -> J/psi K*0 and Bs0 -> J/psi phi, with J/psi -> mu+ mu-, K*0 -> K+ pi- and phi -> K+ K-. The differential cross-sections are measured as functions of B meson transverse momentum pT and rapidity y, in the range 0 < pT < 40 GeV/c and 2.0 < y < 4.5. The integrated cross-sections in the same pT and y ranges, including charge-conjugate states, are measured to be sigma(pp -> B+ + X) = 38.9 +- 0.3 (stat.) +- 2.5 (syst.) +- 1.3 (norm.) mub, sigma(pp -> B0 + X) = 38.1 +- 0.6 (stat.) +- 3.7 (syst.) +- 4.7 (norm.) mub, sigma(pp -> Bs0 + X) = 10.5 +- 0.2 (stat.) +- 0.8 (syst.) +- 1.0 (norm.) mub, where the third uncertainty arises from the pre-existing branching fraction measurements.
In this paper, we report the production cross-section of forward photons in the pseudorapidity regions of $eta,>,10.94$ and $8.99,>,eta,>,8.81$, measured by the LHCf experiment with proton--proton collisions at $sqrt{s}$ = 13 TeV. The results from the analysis of 0.191 $mathrm{nb^{-1}}$ of data obtained in June 2015 are compared to the predictions of several hadronic interaction models that are used in air-shower simulations for ultra-high-energy cosmic rays. Although none of the models agree perfectly with the data, EPOS-LHC shows the best agreement with the experimental data among the models.
The TOTEM collaboration has measured the proton-proton total cross section at $sqrt{s}=13$ TeV with a luminosity-independent method. Using dedicated $beta^{*}=90$ m beam optics, the Roman Pots were inserted very close to the beam. The inelastic scattering rate has been measured by the T1 and T2 telescopes during the same LHC fill. After applying the optical theorem the total proton-proton cross section is $sigma_{rm tot}=(110.6 pm 3.4$) mb, well in agreement with the extrapolation from lower energies. This method also allows one to derive the luminosity-independent elastic and inelastic cross sections: $sigma_{rm el} = (31.0 pm 1.7)$ mb and $sigma_{rm inel} = (79.5 pm 1.8)$ mb.
The cross-section for inelastic proton-proton collisions, with at least one prompt long-lived charged particle of transverse momentum $p_{rm T}>0.2$ GeV/$c$ in the pseudorapidity range $2.0<eta<4.5$, is measured by the LHCb experiment at a centre-of-mass energy of $sqrt{s}=7$ TeV. The cross-section in this kinematic range is determined to be $sigma_{rm inel}^{rm acc} = 55.0 pm 2.4$ mb within the spectrometer acceptance with an experimental uncertainty that is dominated by systematic contributions. Extrapolation to the full phase space, using PYTHIA 6, yields $sigma_{rm inel} = 66.9 pm 2.9 pm 4.4$ mb, where the first uncertainty is experimental and the second is due to the extrapolation.
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