62 research outputs found
Photon Vector Meson Coupling and Vector Meson Properties at Low Temperature Pion Gas
The vector and axial vector current mixing phenomena at low temperature pion
gas by Dey, Eletsky and Ioffe, leads to the low temperature correction of the
photon-vector meson coupling () at order and
the meson mass at order . We show how this {\it low
temperature theorems} involving the photon and vector mesons are satisfied in
the chiral models based on hidden gauge symmetry and the massive Yang-Mills
approach with an explicit meson. We discuss possible phenomenological
consequences of the low temperature corrections in RHIC experiments.Comment: 13 pages, Revtex, 3 figures (available upon request),
DOE/ER/40427-15-N94,TMU-NT94080
Pion electromagnetic form factor at finite temperature
Temperature effects on the electromagnetic couplings of pions in hot hadronic
matter are studied with an effective chiral Lagrangian. We show that the
Ward-Takahashi identity is satisfied at non-zero temperature in the soft pion
limit. The in-medium electromagnetic form factor of the pion is obtained in the
time-like region and shown to be reduced in magnitude, especially near the
vector-meson resonance region. Finally, we discuss the consequences of this
medium effect on dilepton production from hot hadronic matter.Comment: 29 pages (LaTex) + 11 figure
Much Concern but Little Research on Semiconductor Occupational Health Issues
Emerging occupational and environmental issues in the semiconductor industry We humans have experienced historical lessons on the dangers of introducing new techniques and chemicals expecting benefits, while ignoring unexpected harmful side effects. Examples include untreatable diseases (mesothelioma, lung cancer, and asbestosis) caused by asbestos use, human nervous system defects due to pesticides used to increase crop yields, severe health issues due to DDT used to kill malaria-causing mosquitos, and the depletion of the ozone due to Freon use for refrigeration. The semiconductor industry, a microelectronics industry, emerged in the late twentieth century as a brilliant contributor to industrial development, the development of new techniques, increased scientific knowledge, and an advance in human life styles throughout the world. The dark side of this prosperous industry has become apparent in both environmental and occupational health issues since the 1980s in the US and the 1990s in the UK, and in Asian countries including Taiwan, Singapore, and Korea in the 2000s. Environmental health issues occurred in the 1980s in Silico
Thermal effects on dilepton production from annihilation
We study finite temperature effects on dilepton production from pion-pion
annihilation in hot hadronic matter. The softening of the pion dispersion
relation in a medium is found to enhance the production rate of dileptons with
invariant masses in the region of . On the other hand,
the reduction of the pion electromagnetic form factor at finite temperature
leads to a suppression of the dilepton production rate. Including both effects,
we have found that the dilepton yield is slightly enhanced in the invariant
mass region MeV but is suppressed around the vector meson
resonance. We further discuss the relevance of our results to recent
experimental data from the S+Au collisions at CERN/SPS energies by the CERES
collaboration.Comment: 11 pages + 3 figures (figures are not included but available on
request), revte
Properties of vector mesons at finite temperature -effective lagrangian approach-
The properties of -mesons at finite temperature () are examined with
an effective chiral lagrangian in which vector and axial-vector mesons are
included as massive Yang-Mills fields of the chiral symmetry. It is shown that,
at order, the effective mass is not changed but only the mixing effect in
vector and axial-vector correlator appears.Comment: 13 pages (REVTeX), two figures
Pilot KaVA monitoring on the M87 jet: confirming the inner jet structure and superluminal motions at sub-pc scales
We report the initial results of our high-cadence monitoring program on the
radio jet in the active galaxy M87, obtained by the KVN and VERA Array (KaVA)
at 22 GHz. This is a pilot study that preceded a larger KaVA-M87 monitoring
program, which is currently ongoing. The pilot monitoring was mostly performed
every two to three weeks from December 2013 to June 2014, at a recording rate
of 1 Gbps, obtaining the data for a total of 10 epochs. We successfully
obtained a sequence of good quality radio maps that revealed the rich structure
of this jet from <~1 mas to 20 mas, corresponding to physical scales
(projected) of ~0.1-2 pc (or ~140-2800 Schwarzschild radii). We detected
superluminal motions at these scales, together with a trend of gradual
acceleration. The first evidence for such fast motions and acceleration near
the jet base were obtained from recent VLBA studies at 43 GHz, and the fact
that very similar kinematics are seen at a different frequency and time with a
different instrument suggests these properties are fundamental characteristics
of this jet. This pilot program demonstrates that KaVA is a powerful VLBI array
for studying the detailed structural evolution of the M87 jet and also other
relativistic jets.Comment: 10 pages, 9 figures, accepted for publication in PAS
- …