Running of the top quark mass at NNLO in QCD Defranchis, Matteo M.; Kieseler, Jan; Lipka, Katerina ...
The journal of high energy physics,
04/2024, Letnik:
2024, Številka:
4
Journal Article
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A
bstract
The running of the top quark mass (
m
t
) is probed at the next-to-next-to-leading order in quantum chromodynamics for the first time. The result is obtained by comparing calculations in ...the modified minimal subtraction (
) renormalisation scheme to the CMS result on differential measurement of the top quark-antiquark (
) production cross section at
= 13 TeV. The scale dependence of
m
t
is extracted as a function of the invariant mass of the
system, up to an energy scale of about 0.5 TeV. The observed running is found to be in good agreement with the three-loop solution of the renormalisation group equations on quantum chromodynamics.
Summary
Background Capsule endoscopy can identify small bowel mucosal inflammatory change. However, there has been no validated index for capsule endoscopy findings. This manuscript documents the ...development of such an index.
Aim To develop a capsule endoscopy scoring index for small bowel mucosal inflammatory change.
Methods The index was created in four separate steps. First, parameters and descriptors of inflammatory change were identified. Secondly, blinded readers prospectively graded the presence or absence of each parameter on de‐identified videos and graded a perceived global assessment of overall severity. Thirdly, the individual parameters and descriptors were ranked in order of severity. Fourthly, values for each parameter were created using the descent gradient methodology. The premise was to assure that the final numerical score reflected the global assessment and that the global assessment agreed with the ranking of finding severity. Results were compiled for the three categories: no or clinically insignificant change, mild change, and moderate or severe change. Thresholds were determined.
Results The final index includes three parameters: villous oedema, ulcer and stenosis. A score <135 is designated normal or clinically insignificant mucosal inflammatory change, a score between 135 and 790 is mild, and a score ≥790 is moderate to severe.
Conclusion This capsule endoscopy score provides a common language to quantify small bowel inflammatory changes.
Variceal bleeding is a major complication of cirrhosis, and is associated with a 20 % mortality at 6 weeks. Current international guidelines recommend that patients with cirrhosis are screened by ...conventional upper endoscopy (esophagogastroduodenoscopy, EGD) in order to detect esophageal varices. The recently developed PillCam ESO esophageal capsule endoscope has been shown to be an accurate diagnostic tool in the investigation of patients with gastroesophageal reflux and Barrett's esophagus. We compared the PillCam ESO capsule endoscope with EGD for the detection of esophagogastric varices and portal hypertensive gastropathy in patients with cirrhosis.
A pilot trial was conducted at three sites. Patients with cirrhosis who were undergoing clinically indicated EGD for screening or surveillance for esophageal varices underwent a PillCam ESO study followed by an EGD within 48 hours. Capsule videos were assessed by an investigator who was blinded to the patient's medical history and EGD findings.
A total of 23 of the 32 enrolled patients were found to have esophageal varices at both EGD and PillCam ESO endoscopy. In one patient PillCam ESO detected small varices that were not seen at EGD. The overall concordance between PillCam ESO and EGD was 96.9 % for the diagnosis of esophageal varices and 90.6 % for the diagnosis of portal hypertensive gastropathy. There were no adverse events related to PillCam ESO endoscopy.
In a high-prevalence population, PillCam ESO may represent an accurate noninvasive alternative to EGD for the detection of esophageal varices and portal hypertensive gastropathy. A large-scale trial is underway to validate and expand these findings.
A search is presented for a heavy W′ boson resonance decaying to a B or T vector-like quark and a t or a b quark, respectively. The analysis is performed using proton-proton collisions collected with ...the CMS detector at the LHC. The data correspond to an integrated luminosity of 138 fb−1 at a center-of-mass energy of 13 TeV. Both decay channels result in a signature with a t quark, a Higgs or Z boson, and a b quark, each produced with a significant Lorentz boost. The all-hadronic decays of the Higgs or Z boson and of the t quark are selected using jet substructure techniques to reduce standard model backgrounds, resulting in a distinct three-jet W′ boson decay signature. No significant deviation in data with respect to the standard model background prediction is observed. Upper limits are set at 95% confidence level on the product of the W′ boson cross section and the final state branching fraction. A W′ boson with a mass below 3.1 TeV is excluded, given the benchmark model assumption of democratic branching fractions. In addition, limits are set based on generalizations of these assumptions. These are the most sensitive limits to date for this final state.
Measurements of the top quark-antiquark pair production cross section,
$\sigma_\mathrm{t\bar{t}}$, can be used to constrain the strong coupling
constant, $\alpha_{S}$, the top quark mass, ...$m_\mathrm{t}$, and the parton
distribution functions (PDFs). In this poster, the two most recent relevant
results published by the CMS Collaboration are presented. The analyses are
performed using proton-proton collision data at a centre-of-mass energy of 13
TeV recorded by the CMS detector at the CERN LHC in 2016, corresponding to an
integrated luminosity of $35.9~\mathrm{fb^{-1}}$. In the first one,
$\alpha_{S}$ and $m_\mathrm{t}$ are extracted independently from a measurement
of the inclusive $\sigma_\mathrm{t\bar{t}}$, using next-to-next-to-leading
order theoretical predictions. In the second, a measurement of the normalized
triple-differential $\mathrm{t\bar{t}}$ cross section is performed; the result
is then used together with HERA deep-inelastic scattering data to perform a
simultaneous determination of $\alpha_{S}$, $m_\mathrm{t}$, and the PDFs, at
next-to-leading order. As a result, the uncertainty in the gluon PDF and its
correlation with $\alpha_{S}$ are significantly reduced at high parton momentum
fraction, the kinematic range probed by $\mathrm{t\bar{t}}$ production. The
result also yields the most precise determination of the top quark pole mass,
to date.
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