Anomalous Higgs interactions in dimensional deconstruction

Recent LHC experiments have revealed that Higgs is light. As an interesting candidate to accommodate light Higgs, in this paper we adopt the scenario of dimensional deconstruction, where Higgs is redarded as a pseudo-Nambu-Goldstone boson. Though the scenario is formulated in ordinary 4-dimensional space-time, it may also be interpreted as "latticized" gauge-Higgs unification. We point out that in this scenario Higgs interaction with matter field is anomalous, i.e. its coupling deviates from what the standard model predicts. The interplay between the periodicity of physical observables in the Higgs field and the violation of translational invariance along the extra-space due to the latticization is argued to play an essential role to get the anomalous interaction. Though the predicted anomalous Higgs interaction has much similarity to the one in the gauge-Higgs unification, in the case of dimensional deconstruction the anomaly exists even if we do not introduce bulk mass term for the chiral fermion realized by orbifolding, in clear contrast to the case of gauge-Higgs unification. It in turn means that the anomaly goes away in the continuum limit of the extra-space.Comment: 15 page

Impact of graphene quantum capacitance on transport spectroscopy

We demonstrate experimentally that graphene quantum capacitance $C_{\mathrm{q}}$ can have a strong impact on transport spectroscopy through the interplay with nearby charge reservoirs. The effect is elucidated in a field-effect-gated epitaxial graphene device, in which interface states serve as charge reservoirs. The Fermi-level dependence of $C_{\mathrm{q}}$ is manifested as an unusual parabolic gate voltage ($V_{\mathrm{g}}$) dependence of the carrier density, centered on the Dirac point. Consequently, in high magnetic fields $B$, the spectroscopy of longitudinal resistance ($R_{xx}$) vs. $V_{\mathrm{g}}$ represents the structure of the unequally spaced relativistic graphene Landau levels (LLs). $R_{xx}$ mapping vs. $V_{\mathrm{g}}$ and $B$ thus reveals the vital role of the zero-energy LL on the development of the anomalously wide $\nu=2$ quantum Hall state.Comment: 9 pages, 6 figure

Microscopic Model for Photoinduced Magnetism in the Molecular Complex [Mo(IV)(CN)2(CN−CuL)6]8+[Mo(IV)(CN)_2(CN-CuL)_6]^{8+} Perchlorate

A theoretical model for understanding photomagnetism in the heptanuclear complex $[Mo(IV)(CN)_2(CN-CuL)_6]^{8+}$ perchlorate is developed. It is a many-body model involving the active orbitals on the transition metal ions. The model is exactly solved using a valence bond approach. The ground state solution of the model is highly degenerate and is spanned by five S=0 states, nine S=1 states, five S=2 states and one S=3 state. The orbital occupancies in all these states correspond to six $Cu(II)$ ions and one diamagnetic $Mo(IV)$ ion. The optically excited charge-transfer (CT) state in each spin sector occur at nearly the same excitation energy of 2.993 eV for the physically reasonable parameter values. The degeneracy of the CT states is largest in the S=3 sector and so is the transition dipole moment from the ground state to these excited states. Thus laser irradiation with light of this energy results in most intense absorption in the S=3 sector. The life-time of the S=3 excited states is also expected to be the largest as the number of states below that energy is very sparse in this spin sector when compared to other spin sectors. These twin features of our model explain the observed photomagnetism in the $[Mo(IV)(CN)_2(CN-CuL)_6]^{8+}$ complex.Comment: 8 pages, 6 figures and 1 tabl

Flavor Mixing in the Gauge-Higgs Unification

Gauge-Higgs unification is the fascinating scenario solving the hierarchy problem without supersymmetry. In this scenario, the Standard Model (SM) Higgs doublet is identified with extra component of the gauge field in higher dimensions and its mass becomes finite and stable under quantum corrections due to the higher dimensional gauge symmetry. On the other hand, Yukawa coupling is provided by the gauge coupling, which seems to mean that the flavor mixing and CP violation do not arise at it stands. In this talk, we discuss that the flavor mixing is originated from simultaneously non-diagonalizable bulk and brane mass matrices. Then, this mechanism is applied to various flavor changing neutral current (FCNC) processes via Kaluza-Klein (KK) gauge boson exchange at tree level and constraints for compactification scale are obtained.Comment: 5 pages, prepared for the proceedings of the International Workshop on Grand Unified Theories (GUT2012) held at Yukawa Institute for Theoretical Physics, March 15-17 2012, Kyoto, Japa

Evolution from Non-Fermi to Fermi Liquid Transport Properties by Isovalent Doping in BaFe2(As1-xPx)2 Superconductors

The normal-state charge transport is studied systematically in high-quality single crystals of BaFe$_2$(As$_{1-x}$P$_x$)$_2$ ($0 \leq x \leq 0.71$). By substituting isovalent P for As, the spin-density-wave (SDW) state is suppressed and the dome-shaped superconducting phase ($T_c \lesssim 31$ K) appears. Near the SDW end point ($x\approx0.3$), we observe striking linear temperature ($T$) dependence of resistivity in a wide $T$-range, and remarkable low-$T$ enhancement of Hall coefficient magnitude from the carrier number estimates. We also find that the magnetoresistance apparently violates the Kohler's rule and is well scaled by the Hall angle $\Theta_H$ as $\Delta\rho_{xx}/\rho_{xx} \propto \tan^2\Theta_H$. These non-Fermi liquid transport anomalies cannot be attributed to the simple multiband effects. These results capture universal features of correlated electron systems in the presence of strong antiferromagnetic fluctuations.Comment: 4 pages, 4 figure

An augmented moment method for stochastic ensembles with delayed couplings: II. FitzHugh-Nagumo model

Dynamics of FitzHugh-Nagumo (FN) neuron ensembles with time-delayed couplings subject to white noises, has been studied by using both direct simulations and a semi-analytical augmented moment method (AMM) which has been proposed in a recent paper [H. Hasegawa, E-print: cond-mat/0311021]. For $N$-unit FN neuron ensembles, AMM transforms original $2N$-dimensional {\it stochastic} delay differential equations (SDDEs) to infinite-dimensional {\it deterministic} DEs for means and correlation functions of local and global variables. Infinite-order recursive DEs are terminated at the finite level $m$ in the level-$m$ AMM (AMM$m$), yielding $8(m+1)$-dimensional deterministic DEs. When a single spike is applied, the oscillation may be induced if parameters of coupling strength, delay, noise intensity and/or ensemble size are appropriate. Effects of these parameters on the emergence of the oscillation and on the synchronization in FN neuron ensembles have been studied. The synchronization shows the {\it fluctuation-induced} enhancement at the transition between non-oscillating and oscillating states. Results calculated by AMM5 are in fairly good agreement with those obtained by direct simulations.Comment: 15 pages, 3 figures; changed the title with correcting typos, accepted in Phys. Rev. E with some change

Angular momentum at null infinity in higher dimensions

We define the angular momentum at null infinity in higher dimensions. The asymptotic symmetry at null infinity becomes the Poincare group in higher dimensions. This fact implies that the angular momentum can be defined without any ambiguities such as supertranslation in four dimensions. Indeed we can show that the angular momentum in our definition is transformed covariantly with respect to the Poincare group.Comment: 13 page