79 research outputs found
Width difference in the - system with lattice NRQCD
We compute the matrix element of the four-quark operator \Op_S =
in the mixing on
the lattice using NRQCD, which gives a leading contribution in the calculation
of the width difference in the expansion. Using the
next-to-leading formula of Beneke \textit{et al.}, we obtain
= 0.151(37)(36)(17), where the the first error
reflects the uncertainty of = 245(30) MeV, the second error comes
from our calculation of the matrix element of \Op_S, and the third represents
unknown correction.Comment: 17 pages, 6 figures, uses REVTeX, corrected typos, conservative
systematic erro
Shell evolution approaching the N=20 island of inversion : Structure of 26Na
The levels in 26Na with single particle character have been observed for the first time using the d(25Na, pÎł) reaction at 5 MeV/nucleon. The measured excitation energies and the deduced spectroscopic factors are in good overall agreement with (0+1)hÏ shell model calculations performed in a complete spsdfp basis and incorporating a reduction in the N=20 gap. Notably, the 1p3/2 neutron configuration was found to play an enhanced role in the structure of the low-lying negative parity states in 26Na, compared to the isotone 28Al. Thus, the lowering of the 1p3/2 orbital relative to the 0f7/2 occurring in the neighbouring Z=10 and 12 nuclei - 25,27Ne and 27,29Mg - is seen also to occur at Z=11 and further strengthens the constraints on the modelling of the transition into the island of inversion
Physics with the KLOE-2 experiment at the upgraded DANE
Investigation at a --factory can shed light on several debated issues
in particle physics. We discuss: i) recent theoretical development and
experimental progress in kaon physics relevant for the Standard Model tests in
the flavor sector, ii) the sensitivity we can reach in probing CPT and Quantum
Mechanics from time evolution of entangled kaon states, iii) the interest for
improving on the present measurements of non-leptonic and radiative decays of
kaons and eta/eta mesons, iv) the contribution to understand the
nature of light scalar mesons, and v) the opportunity to search for narrow
di-lepton resonances suggested by recent models proposing a hidden dark-matter
sector. We also report on the physics in the continuum with the
measurements of (multi)hadronic cross sections and the study of gamma gamma
processes.Comment: 60 pages, 41 figures; added affiliation for one of the authors; added
reference to section
TRY plant trait database â enhanced coverage and open access
Plant traitsâthe morphological, anatomical, physiological, biochemical and phenological characteristics of plantsâdetermine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of traitâbased plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traitsâalmost complete coverage for âplant growth formâ. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and traitâenvironmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives
Narrowband Searches for Continuous and Long-duration Transient Gravitational Waves from Known Pulsars in the LIGO-Virgo Third Observing Run
Isolated neutron stars that are asymmetric with respect to their spin axis are possible sources of detectable continuous gravitational waves. This paper presents a fully coherent search for such signals from eighteen pulsars in data from LIGO and Virgo's third observing run (O3). For known pulsars, efficient and sensitive matched-filter searches can be carried out if one assumes the gravitational radiation is phase-locked to the electromagnetic emission. In the search presented here, we relax this assumption and allow both the frequency and the time derivative of the frequency of the gravitational waves to vary in a small range around those inferred from electromagnetic observations. We find no evidence for continuous gravitational waves, and set upper limits on the strain amplitude for each target. These limits are more constraining for seven of the targets than the spin-down limit defined by ascribing all rotational energy loss to gravitational radiation. In an additional search, we look in O3 data for long-duration (hours-months) transient gravitational waves in the aftermath of pulsar glitches for six targets with a total of nine glitches. We report two marginal outliers from this search, but find no clear evidence for such emission either. The resulting duration-dependent strain upper limits do not surpass indirect energy constraints for any of these targets. © 2022. The Author(s). Published by the American Astronomical Society
Diurnal Spectral Sensitivity of the Acute Alerting Effects of Light
Study Objectives: Previous studies have demonstrated short-wavelength sensitivity for the acute alerting response to nocturnal light exposure.
We assessed daytime spectral sensitivity in alertness, performance, and waking electroencephalogram (EEG).
Design: Between-subjects (n = 8 per group).
Setting: Inpatient intensive physiologic monitoring unit.
Participants: Sixteen healthy young adults (mean age ± standard deviation = 23.8 ± 2.7 y).
Interventions: Equal photon density exposure (2.8 Ă 1013 photons/cm2/s) to monochromatic 460 nm (blue) or 555 nm (green) light for 6.5 h
centered in the middle of the 16-h episode of wakefulness during the biological day. Results were compared retrospectively to 16 individuals who
were administered the same light exposure during the night.
Measurements and Results: Daytime and nighttime 460-nm light exposure significantly improved auditory reaction time (P < 0.01 and P < 0.05,
respectively) and reduced attentional lapses (P < 0.05), and improved EEG correlates of alertness compared to 555-nm exposure. Whereas
subjective sleepiness ratings did not differ between the two spectral conditions during the daytime (P > 0.05), 460-nm light exposure at night
significantly reduced subjective sleepiness compared to 555-nm light exposure at night (P < 0.05). Moreover, nighttime 460-nm exposure improved
alertness to near-daytime levels.
Conclusions: The alerting effects of short-wavelength 460-nm light are mediated by counteracting both the circadian drive for sleepiness and
homeostatic sleep pressure at night, but only via reducing the effects of homeostatic sleep pressure during the day
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