8,650 research outputs found
LHC Signatures of Two-Higgs-Doublets with Fourth Family
On-going Higgs searches in the light mass window are of vital importance for
testing the Higgs mechanism and probing new physics beyond the standard model
(SM). The latest ATLAS and CMS searches for the SM Higgs boson at the LHC
(7TeV) found some intriguing excesses of events in the \gamma\gamma/VV^*
channels (V=Z,W) around the mass-range of 124-126 GeV. We explore a possible
explanation of the \gamma\gamma and VV^* signals from the light CP-odd Higgs
A^0 or CP-even Higgs h^0 from the general two-Higgs-doublet model with
fourth-family fermions. We demonstrate that by including invisible decays of
the Higgs boson A^0 or h^0 to fourth-family neutrinos, the predicted
\gamma\gamma and VV^* signals can explain the observed new signatures at the
LHC, and will be further probed by the forthcoming LHC runs in 2012.Comment: 22pp, 10 Figs, JHEP published version, references adde
A unified approach to exact solutions of time-dependent Lie-algebraic quantum systems
By using the Lewis-Riesenfeld theory and the invariant-related unitary
transformation formulation, the exact solutions of the {\it time-dependent}
Schr\"{o}dinger equations which govern the various Lie-algebraic quantum
systems in atomic physics, quantum optics, nuclear physics and laser physics
are obtained. It is shown that the {\it explicit} solutions may also be
obtained by working in a sub-Hilbert-space corresponding to a particular
eigenvalue of the conserved generator ({\it i. e.}, the {\it time-independent}
invariant) for some quantum systems without quasi-algebraic structures. The
global and topological properties of geometric phases and their adiabatic limit
in time-dependent quantum systems/models are briefly discussed.Comment: 11 pages, Latex. accepted by Euro. Phys. J.
Supereulerian graphs and the Petersen graph, II
In this note, we verify two conjectures of Catlin in [J. Graph Theory 13 (1989) 465 - 483] for graphs with at most 11 vertices. These are used to prove the following theorem which improves prior results in [10] and [13]:
Let G be a 3-edge-connected simple graph with order n. If n is large and if for every edge 11.v E E(G), d(u) + d(v) 2 % - 2, then either G has a spanning eulerian subgraph or G can be contracted to the Petersen graph
Spectral and optical properties in the antiphase stripe phase of the cuprate superconductors
We investigate the superconducting order parameter, the spectral and optical
properties in a stripe model with spin (charge) domain-derived scattering
potential (). We show that the charge domain-derived scattering
is less effective than the spin scattering on the suppression of
superconductivity. For , the spectral weight concentrates on
the () antinodal region, and a finite energy peak appears in the optical
conductivity with the disappearance of the Drude peak. But for , the spectral weight concentrates on the () nodal region,
and a residual Drude peak exists in the optical conductivity without the finite
energy peak. These results consistently account for the divergent observations
in the ARPES and optical conductivity experiments in several high-
cuprates, and suggest that the "insulating" and "metallic" properties are
intrinsic to the stripe state, depending on the relative strength of the spin
and charge domain-derived scattering potentials.Comment: 7 pages, 4 figure
Optical Monitoring of the Seyfert Galaxy NGC 4151 and Possible Periodicities in the Historical Light Curve
We report B, V, and R band CCD photometry of the Seyfert galaxy NGC 4151
obtained with the 1.0-m telescope at Weihai Observatory of Shandong University
and the 1.56-m telescope at Shanghai Astronomical Observatory from 2005
December to 2013 February. Combining all available data from literature, we
have constructed a historical light curve from 1910 to 2013 to study the
periodicity of the source using three different methods (the Jurkevich method,
the Lomb-Scargle periodogram method and the Discrete Correlation Function
method). We find possible periods of P_1=4\pm0.1, P_2=7.5\pm0.3 and
P_3=15.9\pm0.3 yr.Comment: 8 pages, 5 figures, Accepted by Research in Astronomy and
Astrophysic
Coexistence of the antiferromagnetic and superconducting order and its effect on spin dynamics in electron-doped high- cuprates
In the framework of the slave-boson approach to the model, it is
found that for electron-doped high- cuprates, the staggered
antiferromagnetic (AF) order coexists with superconducting (SC) order in a wide
doping level ranged from underdoped to nearly optimal doping at the mean-field
level. In the coexisting phase, it is revealed that the spin response is
commensurate in a substantial frequency range below a crossover frequency
for all dopings considered, and it switches to the incommensurate
structure when the frequency is higher than . This result is in
agreement with the experimental measurements. Comparison of the spin response
between the coexisting phase and the pure SC phase with a
-wave pairing plus a higher harmonics term (DP+HH) suggests
that the inclusion of the two-band effect is important to consistently account
for both the dispersion of the spin response and the non-monotonic gap behavior
in the electron-doped cuprates.Comment: 6 pages, 5 figure
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