118722743
Correlated metallic state in honeycomb lattice: Orthogonal Dirac semimetal
A novel gapped metallic state coined orthogonal Dirac semimetal is proposed in the honeycomb lattice in terms of Z(2) slave-spin representation of Hubbard model. This state corresponds to the disordered phase of slave spin and has the same thermodynamical and transport properties as a usual Dirac semimetal but its singe-particle excitation is gapped and has nontrivial topological order due to the Z(2) gauge structure. The quantum phase transition from this orthogonal Dirac semimetal to the usual Dirac semimetal is described by a mean-field decoupling with complementary fluctuation analysis and its criticality falls into the universality class of 2 + 1D Ising model while a large anomalous dimension for the physical electron is found at quantum critical point (QCP), which could be considered as a fingerprint of our fractionalized theory when compared to other nonfractionalized approaches. As byproducts, a path integral formalism for the Z(2) slave-spin representation of Hubbard model is constructed and possible relations to other approaches and the sublattice pairing states, which has been argued to be a promising candidate for gapped spin liquid state found in the numerical simulation, are briefly discussed. Additionally, when spin-orbit coupling is considered, the instability of orthogonal Dirac semimetal to the fractionalized quantum spin Hall insulator (fractionalized topological insulator) is also expected. We hope the present work may be helpful for future studies in Z(2) slave-spin theory and related non-Fermi-liquid phases in honeycomb lattice.
32300667
Non-relativistic Josephson junction from holography
A bstractWe construct a Josephson junction in non-relativistic case with a Lifshitz geometry as the dual gravity. We investigate the effect of the Lifshitz scaling in comparison with its relativistic counterpart. The standard sinusoidal relation between the current and the phase difference is found for various Lifshitz scalings characterised by the dynamical critical exponent. We also find the exponential decreasing relation between the condensate of the scalar operator within the barrier at zero current and the width of the weak link, as well as the relation between the critical current and the width. Nevertheless, the coherence lengths obtained from two exponential decreasing relations generically have discrepancies for non-relativistic dual.
118404205
Thermodynamic geometry of black hole in the deformed Hořava-Lifshitz gravity
We investigate the thermodynamic geometry and phase transition of Kehagias-Sfetsos black hole in the deformed Hořava-Lifshitz gravity with coupling constant λ = 1. The phase transition in black-hole thermodynamics is thought to be associated with the divergence of the capacities. And the structures of these divergent points are studied. We also find that the thermodynamic curvature produced by the Ruppeiner metric is positive definite for all r+ > r− and is divergent at η2 = 0 corresponding to the divergent points of CΦ and CT . These results suggest that the microstructure of the black hole has an effective repulsive interaction, which is very similar to the ideal gas of fermions. These may shed some light on the microstructure of the black hole.
39616698
Fermionic zero modes in gauge and gravity backgrounds on T-2
Here we study fermionic zero modes in gauge and gravity backgrounds taking a two-dimensional compact manifold T-2 as extra dimensions. The result is that there exist massless Dirac fermions which have normalizable zero modes under quite general assumptions about these backgrounds on the bulk. Several special cases of gauge background on the torus are discussed and some simple fermionic zero modes axe obtained.
14109465
Fermions coupled with self-dual vortex background on a torus
Abstract: We study fermionic zero modes in the self-dual vortex background on an extra torus in 5+1 dimensions. It is shown that the self-dual vortex arises from the symmetric phase and the asymmetric phase of Higgs field in the context of generalized Abelian Higgs model. Then we analyze the Dirac operator on the extra two-dimensional space and the effective Lagrangian of four-dimensional fermion with the vortex background. Solving the Dirac equation, we obtain the fermionic zero modes in two simple cases. It is shown that the vortex background contributes a phase shift to the fermionic zero modes, and this phase is determined by the topology of the extra dimensions, it can be observed through Aharonov-Bohm effect. For the anti-vortex case, the corresponding zero modes present a singular behavior at the zero point of Higgs field. While for the vacuum one, they are non-singular.
53470154
Competition between s-wave order and d-wave order in holographic superconductors
A bstractWe study competition between s-wave order and d-wave order through two holographic superconductor models. We find that once the coexisting phase appears, it is always thermodynamically favored, and that the coexistence phase is narrow and one condensate tends to kill the other. The phase diagram is constructed for each model in terms of temperature and the ratio of charges of two orders. We further compare the behaviors of some thermodynamic quantities, and discuss the different aspects and identical ones between two models.
5692175
Effects of correlation between merging steps on the global halo formation
The excursion set theory of halo formation is modified by adopting the fractional Brownian motion, to account for possible correlation between merging steps. We worked out analytically the conditional mass function, halo merging rate and formation time distribution in the spherical collapse model. We also developed an approximation for the ellipsoidal collapse model and applied it to the calculation of the conditional mass function and the halo formation time distribution. For models in which the steps are positively correlated, the halo merger rate is enhanced when the accreted mass is less than similar to 25M*, while for the negatively correlated case this rate is reduced. Compared with the standard model in which the steps are uncorrelated, the models with positively correlated steps produce more aged population in small mass haloes and more younger population in large mass haloes, while for the models with negatively correlated steps the opposite is true. An examination of simulation results shows that a weakly positive correlation between successive merging steps appears to fit best. We have also found a systematic effect in the measured mass function due to the finite volume of simulations. In future work, this will be included in the halo model to accurately predict the three-point correlation function estimated from simulations.
121115503
Exact spinon excitations in an integrable ferrimagnetic spin chain
An exactly solvable one-dimensional ferrimagnetic quantum spin chain model with alternating 1/2-spins and 1-spins is proposed and solved via algebraic Bethe ansatz. It is found that the ground state of this model is a ferrimagnetic state with a residual magnetization. It is proven that the low-lying elementary excitations of the system are the varieties of gapless spinons rather than spin waves.
37534317
New precise measurement of the pion weak form factors in pi+-->e+ nugamma decay.
We have measured the pi+-->e+ nugamma branching ratio over a wide region of phase space, based on a total of 65 460 events acquired using the PIBETA detector. Minimum-chi2 fits to the measured (E(e+), E(gamma) energy distributions result in the weak form factor value of F(A)=0.0119(1) with a fixed value of F(V)=0.0259. An unconstrained fit yields F(V)=0.0258(17) and F(A)=0.0117(17). In addition, we have measured a=0.10(6) for the dependence of F(V) on q2, the e+ nu pair invariant mass squared, parametrized as F(V)(q2)=F(V)(0)(1+aq(2)). The branching ratio for the kinematic region E(gamma)>10 MeV and theta(e(+)gamma)>40 degrees is measured to be B(expt)=73.86(54)x10(-8). Earlier deviations we reported in the high-E(gamma)-low-E(e+) kinematic region are resolved without a tensor term. We also derive new values for the pion polarizability alpha(E)=2.78(10)x10(-4) fm3 and neutral pion lifetime tau(pi0)=(8.5+/-1.1)x10(-17) s.
182183518
Neutral hadron production at LEP with the L3 detector
120882513
Study of light hadron spectroscopy at BESIII
Using the samples of 2.25 × 108 J/ψ and 1.06 × 108 ψ′ events collected with the BESIII detector at the BEPCII e+e− collider in 2009, the pp mass threshold enhancement in J/ψ→γpp and X(1835) in J/ψ→γηπ+π− are confirmed. Two new resonances, X(2120) and X(2370), are also observed in the η′π+π− invariant mass spectrum. A narrow structure denoted as X(1870) is seen with a significance of 7.2σ in J/ψ→ωηπ+π−, and the branching ratio of J/ψ→ωη (1405), η(1405)→a0±(980)π∓, a0±(980)→ηπ± is measured for the first time. Direct measurements of a00(980)−f0(980) mixing in the processes J/ψ→φf0(980)→φa00(980)→φηπ0 and ψ′→γχc1, χc1→π0a00(980)→π0f0(980)→π0π+π− are presented to probe the properties of these two scalar states.Using the samples of 2.25 × 108 J/ψ and 1.06 × 108 ψ′ events collected with the BESIII detector at the BEPCII e+e− collider in 2009, the pp mass threshold enhancement in J/ψ→γpp and X(1835) in J/ψ→γηπ+π− are confirmed. Two new resonances, X(2120) and X(2370), are also observed in the η′π+π− invariant mass spectrum. A narrow structure denoted as X(1870) is seen with a significance of 7.2σ in J/ψ→ωηπ+π−, and the branching ratio of J/ψ→ωη (1405), η(1405)→a0±(980)π∓, a0±(980)→ηπ± is measured for the first time. Direct measurements of a00(980)−f0(980) mixing in the processes J/ψ→φf0(980)→φa00(980)→φηπ0 and ψ′→γχc1, χc1→π0a00(980)→π0f0(980)→π0π+π− are presented to probe the properties of these two scalar states.