Evidence for a B-s(0)pi(+/-) State Askew, A.; Aushev, V.; Avila, C. ...
Physical review letters,
07/2016, Letnik:
117, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We report evidence for a narrow structure, X(5568), in the decay sequence X(5568) -> B-s(0)pi(+/-), B-s(0) -> J/psi phi, J/psi -> mu(+)mu(-), phi -> K+K-. This is evidence for the first ...instance of a hadronic state with valence quarks of four different flavors. The mass and natural width of this state are measured to be m = 5567.8 +/- 2.9(stat)(-1.9)(+0.9) (syst) MeV/c(2) and Gamma = 21.9 +/- 6.4(stat)(-2.5)(+5.0) (syst) MeV/c(2). If the decay is X(5568) -> B-s*pi(+/-). B-s(0)gamma pi(+/-) with an unseen gamma, m(X(5568)) will be shifted up by m(B-s*) - m(B-s(0)) similar to 49 MeV/c(2). This measurement is based on 10.4 fb(-1) of p (p) over bar collision data at root s = 1.96 TeV collected by the D0 experiment at the Fermilab Tevatron collider.
Ce
140
(
n
,
γ
)
is a key reaction for slow neutron-capture (
s
-process) nucleosynthesis due to being a bottleneck in the reaction flow. For this reason, it was measured with high accuracy ...(uncertainty
≈
5
%
) at the n_TOF facility, with an unprecedented combination of a high purity sample and low neutron-sensitivity detectors. The measured Maxwellian averaged cross section is up to 40% higher than previously accepted values. Stellar model calculations indicate a reduction around 20% of the
s
-process contribution to the Galactic cerium abundance and smaller sizeable differences for most of the heavier elements. No variations are found in the nucleosynthesis from massive stars.
Published by the American Physical Society
2024
We present evidence for the exotic charged charmoniumlike state Zc±(3900) decaying to J/ψπ± in semi-inclusive weak decays of b-flavored hadrons. The signal is correlated with a parent J/ψπ+π− system ...in the invariant-mass range 4.2–4.7 GeV that would include the exotic structure Y(4260). The study is based on 10.4 fb−1 of pp¯ collision data collected by the D0 experiment at the Fermilab Tevatron collider.
The average energy and multiplicity of prompt
γ
-rays from slow neutron-induced fission of
235
U have been measured using the STEFF spectrometer at the neutron time-of-flight facility n_TOF. The ...individual responses from 11 NaI scintillators were corrected for multiple
γ
-ray interactions, prompt fission neutrons and background counts before being deconvolved to estimate the emitted spectrum of prompt fission
γ
-rays. The results give an average
γ
-ray energy
E
¯
γ
of 1.71(5) MeV and multiplicity
ν
¯
γ
of 2.66(18) considering
γ
-rays emitted within the energy range 0.8–6.8 MeV. The n_TOF data has a slightly larger
E
¯
γ
and smaller
ν
¯
γ
than other recent measurements, however the product of the two is in agreement within quoted uncertainties.
AIM: Tropical forests store 25% of global carbon and harbour 96% of the world's tree species, but it is not clear whether this high biodiversity matters for carbon storage. Few studies have teased ...apart the relative importance of forest attributes and environmental drivers for ecosystem functioning, and no such study exists for the tropics. LOCATION: Neotropics. METHODS: We relate aboveground biomass (AGB) to forest attributes (diversity and structure) and environmental drivers (annual rainfall and soil fertility) using data from 144,000 trees, 2050 forest plots and 59 forest sites. The sites span the complete latitudinal and climatic gradients in the lowland Neotropics, with rainfall ranging from 750 to 4350 mm year⁻¹. Relationships were analysed within forest sites at scales of 0.1 and 1 ha and across forest sites along large‐scale environmental gradients. We used a structural equation model to test the hypothesis that species richness, forest structural attributes and environmental drivers have independent, positive effects on AGB. RESULTS: Across sites, AGB was most strongly driven by rainfall, followed by average tree stem diameter and rarefied species richness, which all had positive effects on AGB. Our indicator of soil fertility (cation exchange capacity) had a negligible effect on AGB, perhaps because we used a global soil database. Taxonomic forest attributes (i.e. species richness, rarefied richness and Shannon diversity) had the strongest relationships with AGB at small spatial scales, where an additional species can still make a difference in terms of niche complementarity, while structural forest attributes (i.e. tree density and tree size) had strong relationships with AGB at all spatial scales. MAIN CONCLUSIONS: Biodiversity has an independent, positive effect on AGB and ecosystem functioning, not only in relatively simple temperate systems but also in structurally complex hyperdiverse tropical forests. Biodiversity conservation should therefore be a key component of the UN Reducing Emissions from Deforestation and Degradation strategy.
The muon system of the Run II DØ detector Abazov, V.M.; Alkhazov, G.; Baldin, B. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2005, Letnik:
552, Številka:
3
Journal Article
Recenzirano
We describe the design, construction, and performance of the upgraded DØ
muon system for Run II of the Fermilab Tevatron collider. Significant improvements have been made to the major subsystems of ...the DØ
muon detector: trigger scintillation counters, tracking detectors, and electronics. The Run II central muon detector has a new scintillation counter system inside the iron toroid and an improved scintillation counter system outside the iron toroid. In the forward region, new scintillation counter and tracking systems have been installed. Extensive shielding has been added in the forward region. A large fraction of the muon system electronics is also new.
We present a measurement of the W boson production charge asymmetry in p$\bar{p}$→W+X→eν+X events at a center of mass energy of 1.96 TeV, using 9.7 fb-1 of integrated luminosity collected with the D0 ...detector at the Fermilab Tevatron Collider. The neutrino longitudinal momentum is determined by using a neutrino weighting method, and the asymmetry is measured as a function of the W boson rapidity. The measurement extends over wider electron pseudorapidity region than previous results and is the most precise to date, allowing for precise determination of proton parton distribution functions in global fits.
We study the production of the exotic charged charmoniumlike state Z(c)(+/-)(3900) in p (p) over bar collisions through the sequential process psi(4260) -> Z(c)(+/-)(3900)(pi)(-/+), ...Z(c)(+/-)(3900) -> J/psi pi(+/-). Using the subsample of candidates originating from semi-inclusive weak decays of b-flavored hadrons, we measure the invariant mass and natural width to be M = 3902.6(-5.0)(+5.2)(stat)(-1.4)(+3.3)(syst) MeV and Gamma = 32(-21)(+28)(stat)(-7)(+26)(syst) MeV, respectively. We search for prompt production of the Z(c)(+/-)(3900) through the same sequential process. No significant signal is observed, and we set an upper limit of 0.70 at the 95% credibility level on the ratio of prompt production to the production via b-hadron decays. The study is based on 10.4 fb(-1) of p (p) over bar collision data collected by the D0 experiment at the Fermilab Tevatron collider.
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