3,556 research outputs found
ROLE OF VOLUNTARY SERVICE ACTIVITIES IN IMPROVING COLLEGE STUDENTS’ MENTAL HEALTH FROM THE PERSPECTIVE OF POSITIVE PSYCHOLOGY
Test of conformal gravity with astrophysical observations
Since it can describe the rotation curves of galaxies without dark matter and
can give rise to accelerated expansion, conformal gravity attracts much
attention recently. As a theory of modified gravity, it is important to test
conformal gravity with astrophysical observations. Here we constrain conformal
gravity with SNIa and Hubble parameter data and investigate whether it suffers
from an age problem with the age of APM~08279+5255. We find conformal gravity
can accommodate the age of APM~08279+5255 at 3 deviation, unlike most
of dark energy models which suffer from an age problem.Comment: 6 pages, 2 figure
The puzzle of anomalously large isospin violations in
The BES-III Collaboration recently report the observation of anomalously
large isospin violations in , where the in the invariant mass
spectrum appears to be much narrower ( 10 MeV) than the peak width
(50 MeV) measured in other processes. We show that a mechanism, named as
triangle singularity (TS), can produce a narrow enhancement between the charged
and neutral thresholds, i.e., . It can also
lead to different invariant mass spectra for
and , which can possibly explain the long-standing puzzle
about the need for two close states and in
and , respectively. The TS could be a key to our
understanding of the nature of and advance our knowledge
about the mixing between and .Comment: 4 pages and 7 eps figures; Journal-matched versio
Threshold Resummation Effects in Neutral Higgs Boson Production by Bottom Quark Fusion at the CERN Large Hadron Collider
We investigate the QCD effects in the production of neutral Higgs bosons via
bottom quark fusion in both the standard model and the minimal supersymmetric
standard model at the CERN Large Hadron Collider. We include the
next-to-leading order (NLO) QCD corrections (including supersymmetric QCD) and
the threshold resummation effects. We use the soft-collinear effective theory
to resum the large logarithms near threshold from soft gluon emission. Our
results show that the resummation effects can enhance the total cross sections
by about 5% compared with the NLO results.Comment: 29pages, 14 figures, version to appear in Physical Review
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