3,296 research outputs found
Inconsistency of QED in the Presence of Dirac Monopoles
A precise formulation of local gauge invariance in QED is presented,
which clearly shows that the gauge coupling associated with the unphysical
longitudinal photon field is non-observable and actually has an arbitrary
value. We then re-examine the Dirac quantization condition and find that its
derivation involves solely the unphysical longitudinal coupling. Hence an
inconsistency inevitably arises in the presence of Dirac monopoles and this can
be considered as a theoretical evidence against their existence. An
alternative, independent proof of this conclusion is also presented.Comment: Extended and combined version, refinements added; 20 LaTex pages,
Published in Z. Phys. C65, pp.175-18
Holographic Gauge Theory with Maxwell Magnetic Field
We first apply the transformation of mixing azimuthal with wrapped coordinate
to the 11D M-theory with a stack N M5-branes to find the spacetime of a stack
of N D4-branes with magnetic field in 10D IIA string theory, after the
Kaluza-Klein reduction. In the near-horizon limit the background becomes the
Melvin magnetic field deformed . Although the solution
represents the D-branes under the Melvin RR one-form we use a simple
observation to see that it also describes the solution of D-branes under the
Maxwell magnetic field. As the magnetic field we consider is the part of the
background itself we have presented an alternative to previous literature,
because our method does not require the assumption of negligible back reaction.
Next, we use the found solution to investigate the meson property through D4/D8
system (Sakai-Sugimoto model) and compare it with those studied by other
authors. Finally, we present a detailed analysis about the Wilson loop therein
and results show that the external Maxwell magnetic field will enhance the
quark-antiquark potential.Comment: Latex 14 pp, add fi
Long-lived neutral-kaon flux measurement for the KOTO experiment
The KOTO ( at Tokai) experiment aims to observe the CP-violating rare
decay by using a long-lived neutral-kaon
beam produced by the 30 GeV proton beam at the Japan Proton Accelerator
Research Complex. The flux is an essential parameter for the measurement
of the branching fraction. Three neutral decay modes, , , and were used to
measure the flux in the beam line in the 2013 KOTO engineering run. A
Monte Carlo simulation was used to estimate the detector acceptance for these
decays. Agreement was found between the simulation model and the experimental
data, and the remaining systematic uncertainty was estimated at the 1.4\%
level. The flux was measured as per protons on a
66-mm-long Au target.Comment: 27 pages, 16 figures. To be appeared in Progress of Theoretical and
Experimental Physic
Measurement of the Phase Difference Between eta00 and eta+- to a Precision of 1^0
We propose to add an additional regenerator to the E731 spectrometer in the MC beamline to enable us to measure the phase difference between the CP violation parameters {eta}{sub 00} and {eta}{sub +-} to an accuracy of 1{sup o}. Very general considerations indicate that CPT conservation requires the phase difference, {Delta}{phi} = Arg({eta}{sub 00}) - Arg({eta}{sub +-}), to be smaller than one degree. The current experimental value is {Delta}{phi} = (9.4 {+-} 5.1){sup o}
Experimental study of the decay
The first dedicated search for the rare neutral-kaon decay
has been carried out in the E391a experiment at the
KEK 12-GeV proton synchrotron. The final upper limit of 2.6 at
the 90% confidence level was set on the branching ratio for the decay.Comment: 23 pages, 27 figures, accepted for publication as a regular article
in Physical Review
Measurement of Cosmic-ray Muons and Muon-induced Neutrons in the Aberdeen Tunnel Underground Laboratory
We have measured the muon flux and production rate of muon-induced neutrons
at a depth of 611 m water equivalent. Our apparatus comprises three layers of
crossed plastic scintillator hodoscopes for tracking the incident cosmic-ray
muons and 760 L of gadolinium-doped liquid scintillator for producing and
detecting neutrons. The vertical muon intensity was measured to be cmssr. The yield of
muon-induced neutrons in the liquid scintillator was determined to be
neutrons/(gcm). A fit to the recently measured neutron
yields at different depths gave a mean muon energy dependence of for liquid-scintillator targets.Comment: 14 pages, 17 figures, 3 table
Search for the decay
We performed a search for the decay with the
E391a detector at KEK. In the data accumulated in 2005, no event was observed
in the signal region. Based on the assumption of
proceeding via parity-violation, we obtained the single event sensitivity to be
, and set an upper limit on the branching ratio to
be at the 90% confidence level. This is a factor of 3.2
improvement compared to the previous results. The results of proceeding via parity-conservation were also presented in this paper
Acetylome of acinetobacter baumannii SK17 reveals a highly-conserved modification of histone-like protein HU
Lysine acetylation is a prevalent post-translational modification in both eukaryotes and prokaryotes. Whereas this modification is known to play pivotal roles in eukaryotes, the function and extent of this modification in prokaryotic cells remain largely unexplored. Here we report the acetylome of a pair of antibiotic-sensitive and -resistant nosocomial pathogen Acinetobacter baumannii SK17-S and SK17-R. A total of 145 lysine acetylation sites on 125 proteins was identified, and there are 23 acetylated proteins found in both strains, including histone-like protein HU which was found to be acetylated at Lys13. HU is a dimeric DNA-binding protein critical for maintaining chromosomal architecture and other DNA-dependent functions. To analyze the effects of site-specific acetylation, homogenously Lys13-acetylated HU protein, HU(K13ac) was prepared by genetic code expansion. Whilst not exerting an obvious effect on the oligomeric state, Lys13 acetylation alters both the thermal stability and DNA binding kinetics of HU. Accordingly, this modification likely destabilizes the chromosome structure and regulates bacterial gene transcription. This work indicates that acetyllysine plays an important role in bacterial epigenetics
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