Measurement of the CP-violating phase ϕs and the B0s meson decay width difference with B0s→J/ψϕ decays in ATLAS
A measurement of the B s 0 decay parameters in the B s 0 → J/ψϕ channel using an integrated luminosity of 14.3 fb−1 collected by the ATLAS detector from 8 TeV pp collisions at the LHC is presented. The measured parameters include the CP -violating phase ϕ s , the decay width Γ sand the width difference between the mass eigenstates ΔΓ s . The values measured for the physical parameters are statistically combined with those from 4.9 fb−1 of 7 TeV data, leading to the following:
In the analysis the parameter ΔΓ s is constrained to be positive. Results for ϕ s and ΔΓ s are also presented as 68% and 95% likelihood contours in the ϕ s -ΔΓ s plane. Also measured in this decay channel are the transversity amplitudes and corresponding strong phases. All measurements are in agreement with the Standard Model predictions.
Searches for the direct electroweak production of supersymmetric charginos, neutralinos, and sleptons in a variety of signatures with leptons andW, Z, and Higgs bosons are presented. Results are based on a sample of protonproton collision data collected at center-of-mass energy √s = 8 TeV with the CMS detector in 2012, corresponding to an integrated luminosity of 19.5 fb−1. The observed event rates are in agreement with expectations from the standard model. These results probe charginos and neutralinos with masses up to 720 GeV, and sleptons up to 260 GeV, depending on the model details.
Measurements of the W±→ℓ±ν and Z→ℓ+ℓ− production cross sections (where ℓ±=e±,μ± ) in proton–proton collisions at s=13 TeV are presented using data recorded by the ATLAS experiment at the Large Hadron Collider, corresponding to a total integrated luminosity of 81 pb −1 . The total inclusive W± -boson production cross sections times the single-lepton-flavour branching ratios are σW+tot=11.83±0.02 (stat)±0.32 (sys)±0.25 (lumi) nb and σW−tot=8.79±0.02 (stat)±0.24 (sys)±0.18 (lumi) nb for W+ and W− , respectively. The total inclusive Z -boson production cross section times leptonic branching ratio, within the invariant mass window 66<mℓℓ<116 GeV , is σZtot=1.981±0.007 (stat)±0.038 (sys)±0.042 (lumi) nb . The W+ , W− , and Z -boson production cross sections and cross-section ratios within a fiducial region defined by the detector acceptance are also measured. The cross-section ratios benefit from significant cancellation of experimental uncertainties, resulting in σW+fid/σW−fid=1.295±0.003 (stat)±0.010 (sys) and σW±fid/σZfid=10.31±0.04 (stat)±0.20 (sys) . Theoretical predictions, based on calculations accurate to next-to-next-to-leading order for quantum chromodynamics and to next-to-leading order for electroweak processes and which employ different parton distribution function sets, are compared to these
Dijet events are studied in the proton-proton collision data set recorded at s=13 TeV with the ATLAS detector at the Large Hadron Collider in 2015 and 2016, corresponding to integrated luminosities of 3.5 fb−1 and 33.5 fb−1 respectively. Invariant mass and angular distributions are compared to background predictions and no significant deviation is observed. For resonance searches, a new method for fitting the background component of the invariant mass distribution is employed. The data set is then used to set upper limits at a 95% confidence level on a range of new physics scenarios. Excited quarks with masses below 6.0 TeV are excluded, and limits are set on quantum black holes, heavy W′ bosons, W* bosons, and a range of masses and couplings in a Z′ dark matter mediator model. Model-independent limits on signals with a Gaussian shape are also set, using a new approach allowing factorization of physics and detector effects. From the angular distributions, a scale of new physics in contact interaction models is excluded for scenarios with either constructive or destructive interference. These results represent a substantial improvement over those obtained previously with lower integrated luminosity.
The dynamics of a two-component Davydov-Scott (DS) soliton with a small mismatch of the initial location or velocity of the high-frequency (HF) component was investigated within the framework of the Zakharov-type system of two coupled equations for the HF and low-frequency (LF) fields. In this system, the HF field is described by the linear Schrödinger equation with the potential generated by the LF component varying in time and space. The LF component in this system is described by the Korteweg-de Vries equation with a term of quadratic influence of the HF field on the LF field. The frequency of the DS soliton`s component oscillation was found analytically using the balance equation. The perturbed DS soliton was shown to be stable. The analytical results were confirmed by numerical simulations.
Radiation conditions are described for various space regions, radiation-induced effects in spacecraft materials and equipment components are considered and information on theoretical, computational, and experimental methods for studying radiation effects are presented. The peculiarities of radiation effects on nanostructures and some problems related to modeling and radiation testing of such structures are considered.