A
bstract
Results are reported from a search for physics beyond the standard model in proton-proton collision events with a charged lepton (electron or muon), two jets identified as originating from ...a bottom quark decay, and significant imbalance in the transverse momentum. The search was performed using a data sample corresponding to 35.9 fb
−1
, collected by the CMS experiment in 2016 at
$$ \sqrt{s}=13 $$
s
=
13
TeV. Events with this signature can arise, for example, from the electroweak production of gauginos, which are predicted in models based on supersymmetry. The event yields observed in data are consistent with the estimated standard model backgrounds. Limits are obtained on the cross sections for chargino-neutralino
$$ \left({\tilde{\chi}}_1^{\pm }{\tilde{\chi}}_2^0\right) $$
χ
˜
1
±
χ
˜
2
0
production in a simplified model of supersymmetry with the decays
$$ {\chi}_1^{\pm}\to {\mathrm{W}}^{\pm }{\tilde{\chi}}_1^0\kern0.5em \mathrm{and}\kern0.5em {\tilde{\chi}}_2^0\to \mathrm{H}{\chi}_1^0 $$
χ
1
±
→
W
±
χ
˜
1
0
and
χ
˜
2
0
→
H
χ
1
0
. Values of
$$ {m}_{{\tilde{\chi}}_1^{\pm }} $$
m
χ
˜
1
±
between 220 and 490 GeV are excluded at 95% confidence level by this search when the
$$ {\tilde{\chi}}_1^0 $$
χ
˜
1
0
is massless, and values of
$$ {m}_{{\tilde{\chi}}_1^0} $$
m
χ
˜
1
0
are 1 excluded up to 110 GeV for
$$ {m}_{{\tilde{\chi}}_1^{\pm }}\approx 450 $$
m
χ
˜
1
±
≈
450
GeV.
A
bstract
A search for a light pseudoscalar Higgs boson (A) produced in association with bottom quarks and decaying into a muon pair is reported. The search uses 19.7 fb
−1
of proton-proton ...collisions at a center-of-mass energy of 8 TeV, collected by the CMS experiment. No signal is observed in the dimuon mass range from 25 to 60 GeV. Upper limits on the cross section times branching fraction,
$$ \sigma \left(\mathrm{pp}\to \mathrm{b}\overline{\mathrm{b}}\mathrm{A}\right)\mathrm{\mathcal{B}}\left(\mathrm{A}\to \mu \mu \right) $$
σ
pp
→
b
b
¯
A
ℬ
A
→
μ
μ
, are set.
1. To assess the prevalence of visual impairment in those patients who sustain proximal hip fracture after a simple fall. 2. To test the validity of a simple screening test to identify patients with ...visual impairment.
Patients on the orthopaedic rehabilitation ward recuperating from proximal hip fracture were recruited. The nurse screener and examining Ophthalmologist independently assessed the patients' distance visual acuity and visual field to confrontation. In addition, the nurse screener assessed for the presence of cataract in the red reflex and the examining Ophthalmologist performed a dilated slit-lamp examination. On completion of the examination, the Ophthalmologist documented the cause(s) of any visual impairment found.
A total of 89 patients were assessed. In all, 29 patients (33%) could be classified as visually impaired using the United States criteria and 52 patients (58%) had a distance visual acuity of 6/18 or worse in at least one eye. The test reliably identified those patients with visual impairment (sensitivity 94% (+/-5%), specificity 92% (+/-6%)), but was less reliable at identifying those patients with potentially remedial visual impairment (sensitivity 70% (+/-10%), specificity 92% (+/-6%)).
The level of visual impairment in this group of patients is high and screening for visual impairment in the elderly with a history of falls is justified. We have demonstrated that a suitably trained member of the rehabilitation team can identify over 94% of those patients with impaired vision. We believe this simple test should now be incorporated into the assessment of all patients requiring rehabilitation after a proximal hip fracture.
Pittsburgh Compound-B (
C-PiB) and
F-florbetapir are amyloid-β (Aβ) positron emission tomography (PET) radiotracers that have been used as endpoints in Alzheimer's disease (AD) clinical trials to ...evaluate the efficacy of anti-Aβ monoclonal antibodies. However, comparing drug effects between and within trials may become complicated if different Aβ radiotracers were used. To study the consequences of using different Aβ radiotracers to measure Aβ clearance, we performed a head-to-head comparison of
C-PiB and
F-florbetapir in a Phase 2/3 clinical trial of anti-Aβ monoclonal antibodies.
Sixty-six mutation-positive participants enrolled in the gantenerumab and placebo arms of the first Dominantly Inherited Alzheimer Network Trials Unit clinical trial (DIAN-TU-001) underwent both
C-PiB and
F-florbetapir PET imaging at baseline and during at least one follow-up visit. For each PET scan, regional standardized uptake value ratios (SUVRs), regional Centiloids, a global cortical SUVR, and a global cortical Centiloid value were calculated. Longitudinal changes in SUVRs and Centiloids were estimated using linear mixed models. Differences in longitudinal change between PET radiotracers and between drug arms were estimated using paired and Welch two sample t-tests, respectively. Simulated clinical trials were conducted to evaluate the consequences of some research sites using
C-PiB while other sites use
F-florbetapir for Aβ PET imaging.
In the placebo arm, the absolute rate of longitudinal change measured by global cortical
C-PiB SUVRs did not differ from that of global cortical
F-florbetapir SUVRs. In the gantenerumab arm, global cortical
C-PiB SUVRs decreased more rapidly than global cortical
F-florbetapir SUVRs. Drug effects were statistically significant across both Aβ radiotracers. In contrast, the rates of longitudinal change measured in global cortical Centiloids did not differ between Aβ radiotracers in either the placebo or gantenerumab arms, and drug effects remained statistically significant. Regional analyses largely recapitulated these global cortical analyses. Across simulated clinical trials, type I error was higher in trials where both Aβ radiotracers were used versus trials where only one Aβ radiotracer was used. Power was lower in trials where
F-florbetapir was primarily used versus trials where
C-PiB was primarily used.
Gantenerumab treatment induces longitudinal changes in Aβ PET, and the absolute rates of these longitudinal changes differ significantly between Aβ radiotracers. These differences were not seen in the placebo arm, suggesting that Aβ-clearing treatments may pose unique challenges when attempting to compare longitudinal results across different Aβ radiotracers. Our results suggest converting Aβ PET SUVR measurements to Centiloids (both globally and regionally) can harmonize these differences without losing sensitivity to drug effects. Nonetheless, until consensus is achieved on how to harmonize drug effects across radiotracers, and since using multiple radiotracers in the same trial may increase type I error, multisite studies should consider potential variability due to different radiotracers when interpreting Aβ PET biomarker data and, if feasible, use a single radiotracer for the best results.
ClinicalTrials.gov NCT01760005. Registered 31 December 2012. Retrospectively registered.
A search is presented for decays beyond the standard model of the 125 GeV Higgs bosons to a pair of light bosons, based on models with extended scalar sectors. Light boson masses between 5 and 62.5 ...GeV are probed in final states containing four tau leptons, two muons and two b quarks, or two muons and two tau leptons. The results are from data in proton-proton collisions corresponding to an integrated luminosity of 19.7 inverse-femtobarns, accumulated by the CMS experiment at the LHC at a center-of-mass energy of 8 TeV. No evidence for such exotic decays is found in the data. Upper limits are set on the product of the cross section and branching fraction for several signal processes. The results are also compared to predictions of two-Higgs-doublet models, including those with an additional scalar singlet.
Users of nonmotorized transportation often travel along low-volume roads in rural, recreational settings. These users thus share the low-volume road with vehicular traffic. In such cases, safety ...issues pertaining to these users, particularly bicyclists, usually arise at crossings where the shared-use low-volume road intersects with another roadway. Shared-use low-volume roads demonstrate operational characteristics similar to those of trails, so many available safety treatments for trail–roadway crossings can be borrowed to apply to intersections involving a shared-use low-volume road. This study focused on developing a systematic treatment selection mechanism to address the safety of users of nonmotorized transportation at such intersections. This mechanism first synthesized the best practices of safety treatments for trail crossings and selected appropriate treatments to include in a pool of treatments that can also be applied to intersections involving shared-use low-volume roads. Second, a decision tree–based treatment selection method was developed to facilitate traffic engineers' selection of suitable treatments from the treatment pool. Each end node of the tree leads to a customized treatment toolbox that contains only those treatments suitable for the specific volume, speed, and lane settings of the study intersection. The decision tree–based method simplifies the treatment selection process and in turn helps professionals substantially save time and increase reliability in their selection of safety treatments for a given intersection involving a shared-use low-volume road. A case study is introduced to demonstrate the benefit of using the decision tree for proposed safety treatments at an intersection involving a shared-use low-volume road.
A search for narrow resonances in dielectron and dimuon invariant mass spectra has been performed using data obtained from proton-proton collisions at sqrt(s)=13 TeV collected with the CMS detector. ...The integrated luminosity for the dielectron sample is 2.7 inverse femtobarns and for the dimuon sample 2.9 inverse femtobarns. The sensitivity of the search is increased by combining these data with a previously analysed set of data obtained at sqrt(s)=8 TeV and corresponding to a luminosity of 20 inverse femtobarns. No evidence for non-standard-model physics is found, either in the 13 TeV data set alone, or in the combined data set. Upper limits on the product of production cross section and branching fraction have also been calculated in a model-independent manner to enable interpretation in models predicting a narrow dielectron or dimuon resonance structure. Limits are set on the masses of hypothetical particles that could appear in new-physics scenarios. For the Z'SSM particle, which arises in the sequential standard model, and for the superstring inspired Z'psi particle, 95% confidence level lower mass limits for the combined data sets and combined channels are found to be 3.37 and 2.82 TeV, respectively. The corresponding limits for Kaluza-Klein gravitons arising in the Randall-Sundrum model of extra dimensions with coupling parameters 0.01 and 0.10 are 1.46 and 3.11 TeV, respectively. These results significantly extend previous limits.
A measurement is presented of the triple-differential dijet cross section at a centre-of-mass energy of 8 $\,\text {TeV}$ using 19.7 $\,\text {fb}^\text {-1}$ of data collected with the CMS detector ...in proton-proton collisions at the LHC. The cross section is measured as a function of the average transverse momentum, half the rapidity separation, and the boost of the two leading jets in the event. The cross section is corrected for detector effects and compared to calculations in perturbative quantum chromodynamics at next-to-leading order accuracy, complemented with electroweak and nonperturbative corrections. New constraints on parton distribution functions are obtained and the inferred value of the strong coupling constant is $\alpha _S(M_\text {Z}) = 0.1199\,\pm {0.0015}\,(\mathrm {exp})\, _{-0.0020}^{+0.0031}\,(\mathrm {theo})$ , where $M_\text {Z}$ is the mass of the Z boson.
A search for the production of a single top quark in association with a Z boson is presented, both to identify the expected standard model process and to search for flavour-changing neutral current ...interactions. The data sample corresponds to an integrated luminosity of 19.7 inverse-femtobarns recorded by the CMS experiment at the LHC in proton-proton collisions at sqrt(s) = 8 TeV. Final states with three leptons (electrons or muons) and at least one jet are investigated. An events yield compatible with tZq standard model production is observed, and the corresponding cross section is measured to be sigma( p p -> t Z q -> l nu b l+ l- q ) = 10 +8/-7 fb with a significance of 2.4 standard deviations. No presence of flavour-changing neutral current production of tZq is observed. Exclusion limits at 95% confidence level on the branching fractions of a top quark decaying to a Z boson and an up or a charm quark are found to be B( t -> Z u ) < 0.022% and B( t -> Z c ) < 0.049%.
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