4,568 research outputs found
An Implication of Ether Drift
The experimental results of the two-photon absorption(TPA) and
M\"{o}ssbauer-rotor(MR) for testing the isotropy of the speed of light are
explained in an ether drift model with a drift velocity of .
Further tests of the ether drift assumption are suggested.Comment: 6 pages,2 postscript figure
Extracting Top Quark CP Violating Dipole Couplings via and Productions at the LHC
We propose to extract the electric and weak dipole moments of the top quark
via and productions at the CERN LHC. With the large
numbers of events available at the LHC, these dipole moments can be measured to
the accuracy of .Comment: 7 pages, 1 postscript figur
Exotic Cooper pairing in multi-orbital models of SrRuO
The unconventional superconductivity in SrRuO continues to defy a
unified interpretation. In this paper, we focus on some novel aspects of its
superconducting pairing by exploiting the orbital degree of freedom in this
material. The multi-orbital nature, combined with the symmetry of the orbitals
involved, leads to a plethora of exotic Cooper pairings not accessible in
single-orbital systems. Essential physics is illustrated first using a
two-orbital model with - and -orbitals. We classify the gap
functions according to the underlying lattice symmetries, analyze the effective
theories of a few representative pairings, and make connections to
SrRuO in the course. In particular, we show how spin-orbit coupling may
entangle spin-triplet and spin-singlet pairings. For completeness, the
classification is generalized to the three-orbital model involving the
-orbital as well. The orbital-basis approach distinguishes from the
itinerant-band description for SrRuO, and hence offers an alternative
perspective to investigate its enigmatic superconducting state.Comment: 7 pages, 1 figure and 2 tables. Published versio
Constructing current singularity in a 3D line-tied plasma
We revisit Parker's conjecture of current singularity formation in 3D
line-tied plasmas using a recently developed numerical method, variational
integration for ideal magnetohydrodynamics in Lagrangian labeling. With the
frozen-in equation built-in, the method is free of artificial reconnection, and
hence it is arguably an optimal tool for studying current singularity
formation. Using this method, the formation of current singularity has
previously been confirmed in the Hahm--Kulsrud--Taylor problem in 2D. In this
paper, we extend this problem to 3D line-tied geometry. The linear solution,
which is singular in 2D, is found to be smooth for arbitrary system length.
However, with finite amplitude, the linear solution can become pathological
when the system is sufficiently long. The nonlinear solutions turn out to be
smooth for short systems. Nonetheless, the scaling of peak current density
versus system length suggests that the nonlinear solution may become singular
at finite length. With the results in hand, we can neither confirm nor rule out
this possibility conclusively, since we cannot obtain solutions with system
length near the extrapolated critical value
Neutralino pair production at proton-proton collider
In this paper we investigated the Drell-Yan process of the light neutralino
pair productions at hadron
colliders. We studied the dependence of the coupling properties of two light
neutralino on the three SUSY Lagrangian parameters
, and , and find that the production rate of pair will be dominated by the Higgsino-like couplings under
the condition and , while the productions of
and pairs
will be enhanced by the gaugino-like couplings under . For the
Higgsino-like neutralinos, the cross section of
production at the LHC can reach .Comment: LaTex file, 15 pages, 8 EPS figure
Solving the Jaynes-Cummings Model with Shift Operators Constructed by Means of the Matrix-Diagonalizing Technique
The Jaynes-Cummings model is solved with the raising and lowering (shift)
operators by using the matrix-diagonalizing technique. Bell nonlocality is also
found present ubiquitously in the excitations states of the model.Comment: 5 page
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pH-dependent gating mechanism of the Helicobacter pylori urea channel revealed by cryo-EM.
The urea channel of Helicobacter pylori (HpUreI) is an ideal drug target for preventing gastric cancer but incomplete understanding of its gating mechanism has hampered development of inhibitors for the eradication of H. pylori. Here, we present the cryo-EM structures of HpUreI in closed and open conformations, both at a resolution of 2.7 Ã…. Our hexameric structures of this small membrane protein (~21 kDa/protomer) resolve its periplasmic loops and carboxyl terminus that close and open the channel, and define a gating mechanism that is pH dependent and requires cooperativity between protomers in the hexamer. Gating is further associated with well-resolved changes in the channel-lining residues that modify the shape and length of the urea pore. Site-specific mutations in the periplasmic domain and urea pore identified key residues important for channel function. Drugs blocking the urea pore based on our structures should lead to a new strategy for H. pylori eradication
t anti-t Production Rates at the Tevatron and the LHC in Topcolor- Assisted Multiscale Technicolor Models
We study the contributions of the neutral pseudo Goldstone bosons
(technipions and top-pions) to the t anti-t production cross sections at the
Tevatron and the LHC in topcolor-assisted multiscale technicolor (TOPCMTC)
models via the gluon-gluon fusion process from the loop-level couplings between
the pseudo Goldstone bosons and the gluons. The MRS set A' parton distributions
are used in the calculation. It is shown that the new CDF datum on the t anti-t
production cross section gives constraints on the parameters in the TOPCMTC
models. With reasonable values of the parameters in TOPCMTC models, the cross
section at the Tevatron is larger than that predicted by the standard model,
and is consistent with the new CDF data. The enhancement of the cross section
and the resonance peaks at the LHC are more significant, so that it is testable
in future experiments.Comment: 16 pages in RevTex, 9 postscript figure
Magnetohydrodynamical equilibria with current singularities and continuous rotational transform
We revisit the Hahm-Kulsrud-Taylor (HKT) problem, a classic prototype problem
for studying resonant magnetic perturbations and 3D magnetohydrodynamical
equilibria. We employ the boundary-layer techniques developed by Rosenbluth,
Dagazian, and Rutherford (RDR) for the internal kink instability, while
addressing the subtle difference in the matching procedure for the HKT problem.
Pedagogically, the essence of RDR's approach becomes more transparent in the
simplified slab geometry of the HKT problem. We then compare the boundary-layer
solution, which yields a "DC" current singularity at the resonant surface, to
the numerical solution obtained using a flux-preserving Grad-Shafranov solver.
The remarkable agreement between the solutions demonstrates the validity and
universality of RDR's approach. In addition, we show that RDR's approach
consistently preserves the rotational transform, which hence stays continuous,
contrary to a recent claim that RDR's solution contains a discontinuity in the
rotational transform.Comment: 8 pages, 3 figure
Metallicity and Star Formation Activities of the Interacting System Arp 86 from Observation with MOS on Xinglong 2.16m Telescope
We present an analysis of the metallicity and star formation activities of
HII regions in the interacting system Arp 86, based on the first scientific
observation of the multi-object spectroscopy on the 2.16m Telescope at Xinglong
Observatory. We find that the oxygen abundance gradient in Arp 86 is flatter
than that in normal disk galaxies, which confirms that gas inflows caused by
tidal forces during encounters can flatten the metallicity distributions in
galaxies. The companion galaxy NGC 7752 is currently experiencing a galaxy-wide
starburst with higher surface density of star formation rate than the main
galaxy NGC 7753, which can be explained that the companion galaxy is more
susceptible to the effects of interaction than the primary. We also find that
the galaxy 2MASX J23470758+2926531 has similar abundance and star formation
properties to NGC 7753, and may be a part of the Arp 86 system.Comment: 16 pages, 7 figures, accepted by RA
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