807 research outputs found
The Physics Case for the New Muon (g-2) Experiment
This White Paper briefly reviews the present status of the muon (g-2)
experiment and the physics motivation for a new effort. The present comparison
between experiment and theory indicates a tantalizing deviation.
An improvement in precision on this comparison by a factor of 2--with the
central value remaining unchanged--will exceed the ``discovery'' threshold,
with a sensitivity above . The 2.5-fold reduction improvement goal of
the new Brookhaven E969 experiment, along with continued steady reduction of
the standard model theory uncertainty, will achieve this more definitive test.
Already, the (g-2) result is arguably the most compelling indicator of
physics beyond the standard model and, at the very least, it represents a major
constraint for speculative new theories such as supersymmetry or extra
dimensions. In this report, we summarize the present experimental status and
provide an up-to-date accounting of the standard model theory, including the
expectations for improvement in the hadronic contributions, which dominate the
overall uncertainty. Our primary focus is on the physics case that motivates
improved experimental and theoretical efforts. Accordingly, we give examples of
specific new-physics implications in the context of direct searches at the LHC
as well as general arguments about the role of an improved (g-2) measurement. A
brief summary of the plans for an upgraded effort complete the report.Comment: 18 pages, 7 figure
Addressing the Well-Being of Young Children
The COVID-19 pandemic has disrupted young learners\u27 daily routines, learning environments, and home life stability, severely impacting their well-being. Children\u27s issues with mental health, such as anxiety, stress, and depression, significantly impact their ability and interest to achieve in school settings. Additionally, the pandemic affected parents, caregivers, and educators, which had repercussions on their children and students. The authors conducted a literature review, identifying 26 articles that reported on young children\u27s mental health and well-being with a particular interest in the impacts of the COVID-19 pandemic and identified gifted children. This review illuminated some main themes: young children have mental health issues; parents, caregivers, and the environment impact the well-being of young children; mental health services are not readily available to support families and their young children; COVID-19 adversely impacted students, caregivers, and teachers; and strategies exist to better understand and support young children, their families, caregivers, and teachers. Therefore, it is essential to understand the impacts on young children\u27s mental health and how to best support them during these unprecedented times
Magic, Religion, and Science: Secularization Trends and Continued Coexistence
While multiple studies have applied cultural evolutionary perspectives to the study of religion, few studies have examined the cultural evolutionary dynamics of a more secretive but equally ubiquitous form of supernatural belief: magic. We conducted two studies, an American nationally representative survey and a comparative phylogenetic analysis of religious traditions, to test three hypothesized cultural evolutionary drivers for beliefs in magic. We find the greatest support for the hypothesis that magic is employed when it provides its users benefits that are distinct from those provided by either science or religion, some support for secularization (broadly conceived) trends applying to magic, and no evidence that innate and unavoidable features of human cognition are primary drivers of the cultural evolution of magical beliefs. We conclude by suggesting specific hypothesized benefits for magic that may account for the evolution of humanity's facultative (i.e., contextâdependent) use of magical beliefs
Enhancing Vibrational Light-Matter Coupling Strength beyond the Molecular Concentration Limit Using Plasmonic Arrays
Vibrational strong coupling is emerging as a promising tool to modify molecular properties by making use of hybrid light-matter states known as polaritons. Fabry-Perot cavities filled with organic molecules are typically used, and the molecular concentration limits the maximum reachable coupling strength. Developing methods to increase the coupling strength beyond the molecular concentration limit are highly desirable. In this Letter, we investigate the effect of adding a gold nanorod array into a cavity containing pure organic molecules using FT-IR microscopy and numerical modeling. Incorporation of the plasmonic nanorod array that acts as artificial molecules leads to an order of magnitude increase in the total coupling strength for the cavity with matching resonant frequency filled with organic molecules. Additionally, we observe a significant narrowing of the plasmon line width inside the cavity. We anticipate that these results will be a step forward in exploring vibropolaritonic chemistry and may be used in plasmon based biosensors
Analysis of a jet stream induced gravity wave associated with an observed ice cloud over Greenland
International audienceA polar stratospheric ice cloud (PSC type II) was observed by airborne lidar above Greenland on 14 January 2000. It was the unique observation of an ice cloud over Greenland during the SOLVE/THESEO 2000 campaign. Mesoscale simulations with the hydrostatic HRM model are presented which, in contrast to global analyses, are capable to produce a vertically propagating gravity wave that induces the low temperatures at the level of the PSC afforded for the ice formation. The simulated minimum temperature is ~8 K below the driving analyses and ~4.5 K below the frost point, exactly coinciding with the location of the observed ice cloud. Despite the high elevations of the Greenland orography the simulated gravity wave is not a mountain wave. Analyses of the horizontal wind divergence, of the background wind profiles, of backward gravity wave ray-tracing trajectories, of HRM experiments with reduced Greenland topography and of several diagnostics near the tropopause level provide evidence that the wave is emitted from an intense, rapidly evolving, anticyclonically curved jet stream. The precise physical process responsible for the wave emission could not be identified definitely, but geostrophic adjustment and shear instability are likely candidates. In order to evaluate the potential frequency of such non-orographic polar stratospheric cloud events, the non-linear balance equation diagnostic is performed for the winter 1999/2000. It indicates that ice-PSCs are only occasionally generated by gravity waves emanating from spontaneous adjustment
Measurement of the Positive Muon Lifetime and Determination of the Fermi Constant to Part-per-Million Precision
We report a measurement of the positive muon lifetime to a precision of 1.0
parts per million (ppm); it is the most precise particle lifetime ever
measured. The experiment used a time-structured, low-energy muon beam and a
segmented plastic scintillator array to record more than 2 x 10^{12} decays.
Two different stopping target configurations were employed in independent
data-taking periods. The combined results give tau_{mu^+}(MuLan) =
2196980.3(2.2) ps, more than 15 times as precise as any previous experiment.
The muon lifetime gives the most precise value for the Fermi constant:
G_F(MuLan) = 1.1663788 (7) x 10^-5 GeV^-2 (0.6 ppm). It is also used to extract
the mu^-p singlet capture rate, which determines the proton's weak induced
pseudoscalar coupling g_P.Comment: Accepted for publication in Phys. Rev. Let
Effect of gravity wave temperature fluctuations on homogeneous ice nucleation in the tropical tropopause layer
The impact of high-frequency fluctuations of temperature on
homogeneous nucleation of ice crystals in the vicinity of the
tropical tropopause is investigated using a bin microphysics scheme
for air parcels. The imposed temperature fluctuations come from
measurements during isopycnic balloon flights near the tropical
tropopause. The balloons collected data at high frequency,
guaranteeing that gravity wave signals are well resolved.With the observed temperature time series, the numerical simulations
with homogeneous freezing show a full range of ice number
concentration (INC) as previously observed in the tropical upper
troposphere. In particular, a low INC may be obtained if the gravity
wave perturbations produce a non-persistent cooling rate (even with
large magnitude) such that the absolute change in temperature
remains small during nucleation. This result is explained
analytically by a dependence of the INC on the absolute drop in
temperature (and not on the cooling rate). This work suggests that
homogeneous ice nucleation is not necessarily inconsistent
with observations of low INCs.</p
Discovering the New Standard Model: Fundamental Symmetries and Neutrinos
This White Paper describes recent progress and future opportunities in the
area of fundamental symmetries and neutrinos.Comment: Report of the Fundamental Symmetries and Neutrinos Workshop, August
10-11, 2012, Chicago, I
Sensitive Search for a Permanent Muon Electric Dipole Moment
We are proposing a new method to carry out a dedicated search for a permanent
electric dipole moment (EDM) of the muon with a sensitivity at a level of
10^{-24} e cm. The experimental design exploits the strong motional electric
field sensed by relativistic particles in a magnetic storage ring. As a key
feature, a novel technique has been invented in which the g-2 precession is
compensated with radial electric field. This technique will benefit greatly
when the intense muon sources advocated by the developers of the muon storage
rings and the muon colliders become available.Comment: 16 pages, 3 figures. Submitted for publication in Proceedings of the
International Workshop on High Intensity Muon Sources (HIMUS99), KEK, Japan,
December 1-4 199
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