172 research outputs found
Search for CP violation in D+âÏÏ+ and D+sâK0SÏ+ decays
A search for CP violation in D + â ÏÏ + decays is performed using data collected in 2011 by the LHCb experiment corresponding to an integrated luminosity of 1.0 fbâ1 at a centre of mass energy of 7 TeV. The CP -violating asymmetry is measured to be (â0.04 ± 0.14 ± 0.14)% for candidates with K â K + mass within 20 MeV/c 2 of the Ï meson mass. A search for a CP -violating asymmetry that varies across the Ï mass region of the D + â K â K + Ï + Dalitz plot is also performed, and no evidence for CP violation is found. In addition, the CP asymmetry in the D+sâK0SÏ+ decay is measured to be (0.61 ± 0.83 ± 0.14)%
Longitudinal, population-based study of racial/ethnic differences in colorectal cancer survival: impact of neighborhood socioeconomic status, treatment and comorbidity
<p>Abstract</p> <p>Background</p> <p>Colorectal cancer, if detected early, has greater than 90% 5-year survival. However, survival has been shown to vary across racial/ethnic groups in the United States, despite the availability of early detection methods.</p> <p>Methods</p> <p>This study evaluated the joint effects of sociodemographic factors, tumor characteristics, census-based socioeconomic status (SES), treatment, and comorbidities on survival after colorectal cancer among and within racial/ethnic groups, using the SEER-Medicare database for patients diagnosed in 1992â1996, and followed through 1999.</p> <p>Results</p> <p>Unadjusted colorectal cancer-specific mortality rates were higher among Blacks and Hispanic males than whites (relative rates (95% confidence intervals) = 1.34 (1.26â1.42) and 1.16 (1.04â1.29), respectively), and lower among Japanese (0.78 (0.70â0.88)). These patterns were evident for all-cause mortality, although the magnitude of the disparity was larger for colorectal cancer mortality. Adjustment for stage accounted for the higher rate among Hispanic males and most of the lower rate among Japanese. Among Blacks, stage and SES accounted for about half of the higher rate relative to Whites, and within stage III colon and stages II/III rectal cancer, SES completely accounted for the small differentials in survival between Blacks and Whites. Comorbidity did not appear to explain the Black-White differentials in colorectal-specific nor all-cause mortality, beyond stage, and treatment (surgery, radiation, chemotherapy) explained a very small proportion of the Black-White difference. The fully-adjusted relative mortality rates comparing Blacks to Whites was 1.14 (1.09â1.20) for all-cause mortality and 1.21 (1.14â1.29) for colorectal cancer specific mortality. The sociodemographic, tumor, and treatment characteristics also had different impacts on mortality within racial/ethnic groups.</p> <p>Conclusion</p> <p>In this comprehensive analysis, race/ethnic-specific models revealed differential effects of covariates on survival after colorectal cancer within each group, suggesting that different strategies may be necessary to improve survival in each group. Among Blacks, half of the differential in survival after colorectal cancer was primarily attributable to stage and SES, but differences in survival between Blacks and Whites remain unexplained with the data available in this comprehensive, population-based, analysis.</p
Updated measurements of exclusive J/Ï and Ï(2S) production cross-sections in pp collisions at âs = 7 TeV
The differential cross-section as a function of rapidity has been measured for the exclusive production of J/Ï and Ï(2S) mesons in protonâproton collisions at âs = 7 TeV, using data collected by the LHCb experiment, corresponding to an integrated luminosity of 930 pbâ1. The cross-sections times branching fractions to two muons having pseudorapidities between 2.0 and 4.5 are measured to be where the first uncertainty is statistical and the second is systematic. The measurements agree with next-to-leading order QCD predictions as well as with models that include saturation effects
Measurement of the Îb0, Îb-, and Ωb- Baryon Masses
Bottom baryons decaying to a J/Ï meson and a hyperon are reconstructed using 1.0ââfb-1 of data collected in 2011 with the LHCb detector. Significant Îb0âJ/ÏÎ, Îb-âJ/ÏÎ- and Ωb-âJ/ÏΩ- signals are observed and the corresponding masses are measured to be M(Îb0)=5619.53±0.13(stat.)±0.45(syst.)ââMeV/c2, M(Îb-)=5795.8±0.9(stat.)±0.4(syst.)ââMeV/c2, M(Ωb-)=6046.0±2.2(stat.)±0.5(syst.)ââMeV/c2, while the differences with respect to the Îb0 mass are M(Îb-)-M(Îb0)=176.2±0.9(stat.)±0.1(syst.)ââMeV/c2, M(Ωb-)-M(Îb0)=426.4±2.2(stat.)±0.4(syst.)ââMeV/c2. These are the most precise mass measurements of the Îb0, Îb- and Ωb- baryons to date. Averaging the above Îb0 mass measurement with that published by LHCb using 35ââpb-1 of data collected in 2010 yields M(Îb0)=5619.44±0.13(stat.)±0.38(syst.)ââMeV/c2
Measurement of D s <sup>±</sup> production asymmetry in pp collisions at âs=7 and 8 TeV
The inclusive production asymmetry is measured in collisions
collected by the LHCb experiment at centre-of-mass energies of
and 8 TeV. Promptly produced mesons are used, which decay as
, with . The measurement is
performed in bins of transverse momentum, , and rapidity, ,
covering the range GeV and . No kinematic
dependence is observed. Evidence of nonzero production asymmetry is
found with a significance of 3.3 standard deviations.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2018-010.htm
Search for CP violation in Îb0âpKâ and Îb0âpÏâ decays
A search for CP violation in Îb0âpKâ and Îb0âpÏâ decays is presented using a sample of pp collisions collected with the LHCb detector and corresponding to an integrated luminosity of 3.0fbâ1. The CP -violating asymmetries are measured to be ACPpKâ=â0.020±0.013±0.019 and ACPpÏâ=â0.035±0.017±0.020, and their difference ACPpKââACPpÏâ=0.014±0.022±0.010, where the first uncertainties are statistical and the second systematic. These are the most precise measurements of such asymmetries to date
FCC-ee: The Lepton Collider: Future Circular Collider Conceptual Design Report Volume 2
In response to the 2013 Update of the European Strategy for Particle Physics, the Future Circular Collider (FCC) study was launched, as an international collaboration hosted by CERN. This study covers a highest-luminosity high-energy lepton collider (FCC-ee) and an energy-frontier hadron collider (FCC-hh), which could, successively, be installed in the same 100 km tunnel. The scientific capabilities of the integrated FCC programme would serve the worldwide community throughout the 21st century. The FCC study also investigates an LHC energy upgrade, using FCC-hh technology. This document constitutes the second volume of the FCC Conceptual Design Report, devoted to the electron-positron collider FCC-ee. After summarizing the physics discovery opportunities, it presents the accelerator design, performance reach, a staged operation scenario, the underlying technologies, civil engineering, technical infrastructure, and an implementation plan. FCC-ee can be built with todayâs technology. Most of the FCC-ee infrastructure could be reused for FCC-hh. Combining concepts from past and present lepton colliders and adding a few novel elements, the FCC-ee design promises outstandingly high luminosity. This will make the FCC-ee a unique precision instrument to study the heaviest known particles (Z, W and H bosons and the top quark), offering great direct and indirect sensitivity to new physics
FCC Physics Opportunities: Future Circular Collider Conceptual Design Report Volume 1
We review the physics opportunities of the Future Circular Collider, covering its e+e-, pp, ep and heavy ion programmes. We describe the measurement capabilities of each FCC component, addressing the study of electroweak, Higgs and strong interactions, the top quark and flavour, as well as phenomena beyond the Standard Model. We highlight the synergy and complementarity of the different colliders, which will contribute to a uniquely coherent and ambitious research programme, providing an unmatchable combination of precision and sensitivity to new physics
Studies of beauty baryon decays to D0phâ and Î+châ final states
Decays of beauty baryons to the D0phâ and Î+châ final states (where h indicates a pion or a kaon) are studied using a data sample of pp collisions, corresponding to an integrated luminosity of 1.0ââfbâ1, collected by the LHCb detector. The Cabibbo-suppressed decays Î0bâD0pKâ and Î0bâÎ+cKâ are observed, and their branching fractions are measured with respect to the decays Î0bâD0pÏâ and Î0bâÎ+cÏâ. In addition, the first observation is reported of the decay of the neutral beauty-strange baryon Î0b to the D0pKâ final state, and a measurement of the Î0b mass is performed. Evidence of the Î0bâÎ+cKâ decay is also reported
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