A
bstract
A new class of higher-spin gauge theories associated with various Coxeter groups is proposed. The emphasize is on the
B
p
-models. The cases of
B
1
and its infinite graded-symmetric product
...sym
(×
B
1
)
∞
correspond to the usual higher-spin theory and its multi-particle extension, respectively. The multi-particle
B
2
-higher-spin theory is conjectured to be associated with String Theory.
B
p
-higher-spin models with
p >
2 are anticipated to be dual to the rank-
p
boundary tensor sigma-models.
B
p
higher-spin models with
p
≥ 2 possess two coupling constants responsible for higher-spin interactions in AdS background and stringy/tensor effects, respectively. The brane-like idempotent extension of the Coxeter higher-spin theory is proposed allowing to unify in the same model the fields supported by space-times of different dimensions. Consistency of the holographic interpretation of the boundary matrix-like model in the
B
2
-higher-spin model is shown to demand
N
≥ 4 SUSY, suggesting duality with the
N
= 4 SYM upon spontaneous breaking of higher-spin symmetries. The proposed models are shown to admit unitary truncations.
A
bstract
A new efficient approach to the analysis of nonlinear higher-spin equations, that treats democratically auxiliary spinor variables
Z
A
and integration homotopy parameters in the non-linear ...vertices of the higher-spin theory, is developed. Being most general, the proposed approach is the same time far simpler than those available so far. In particular, it is free from the necessity to use the Schouten identity. Remarkably, the problem of reconstruction of higher-spin vertices is mapped to certain polyhedra cohomology in terms of homotopy parameters themselves. The new scheme provides a powerful tool for the study of higher-order corrections in higher-spin theory and, in particular, its spin-locality. It is illustrated by the analysis of the lower order vertices, reproducing not only the results obtained previously by the shifted homotopy approach but also projectively-compact vertices with the minimal number of derivatives, that were so far unreachable within that scheme.
Quantum hashing is one of the techniques that allow to construct space-efficient quantum algorithms and protocols. We present a construction that allows to make it extremely time efficient. Our ...approach is based on the shallow implementation of the quantum fingerprinting technique but uses additional circuit identities specific to the quantum hash function for the cyclic group. The resulting algorithm is equivalent to the one we have implemented earlier using single-photon states with orbital angular momentum encoding.
A
bstract
Properties of the resolution operator d
loc
∗
in higher-spin equations, that leads to local current interactions at the cubic order and minimally nonlocal higher-order corrections, are ...formulated in terms of the condition on the class of master fields of higher-spin theory that restricts both the dependence on the spinor
Y
,
Z
variables and on the contractions of indices between the constituent fields in bilinear terms. The Green function in the sector of zero-forms is found for the case of constituent fields carrying helicities of opposite signs. It is shown that the local resolution d
loc
∗
differs from the conventional De Rham resolution d
Z
∗
by a non-local shift.
A
bstract
The analysis of spin-locality of higher-spin gauge theory is formulated in terms of star-product functional classes appropriate for the
β
→ −∞ limiting shifted homotopy proposed recently in ...
1
where all
ω
2
C
2
higher-spin vertices were shown to be spin-local. For the
β
→ −∞ limiting shifted contracting homotopy we identify the class of functions
H
+
0
, that do not contribute to the r.h.s. of HS field equations at a given order. A number of theorems and relations that organize analysis of the higher-spin equations are derived including extension of the Pfaffian Locality Theorem of
2
to the
β
-shifted contracting homotopy and the relation underlying locality of the
ω
2
C
2
sector of higher-spin equations.
Space-time interpretation of spin-locality of theories involving infinite towers of fields is proposed as the property that the theory is space-time local in terms of original con- stituent fields
ϕ
and their local currents
J
(
ϕ
) of all ranks. Spin-locality is argued to be a proper substitute of locality for theories with finite sets of fields for which the two concepts are equivalent.
•The structure of thermal boundary layer in case of mixed boundary conditions is examined.•It is shown that thickness of thermal boundary layer strongly depends on the heater size.•The mechanism of ...thermal boundary layer formation is proposed.•The crucial factor of the ratio of the heater size and thickness of thermal boundary layer is shown.
A series of numerical simulations of Rayleigh-Bénard convection in a cubic cavity are conducted in order to examine the structure of the thermal boundary layer in case of mixed boundary conditions. The main goal of the study is the physical mechanism which provides increasing of heat flux with spatial frequency of conducting-adiabatic pattern. Different spatial configuration of conducting plates, including the fractal one, are considered for Rayleigh numbers from Ra=107 to Ra=2.0×109. We have shown that the temperature boundary layer in case of mixed boundary conditions at the bottom is strongly non-uniform. This non-homogeneity is a result of several factors such as conducting-adiabatic pattern, large-scale circulation and small-scale motions over conducting plates. The thickness of the thermal boundary layer strongly depends on the size of the conducting plates and can be substantially smaller than for a classical Rayleigh-Bénard convection. This effect increases the heat flux with decreasing the size of hot plates, which corresponds to the increasing of spatial frequency of conducting-adiabatic pattern.
A
bstract
We analyse higher-spin theory with general coupling constant
η
at the second order, focusing on the gauge non-invariant vertices Υ(
ω
,
ω
), Υ(Ω,
ω
,
C
) and Υ(
ω
,
C
), that are shown to ...generate nontrivial currents in the Fronsdal equations. Explicit expressions for the currents are found in the frame-like formalism counterpart of the TT gauge worked out in the paper. The nonlinear higher-spin theory is shown to generate all types of Metsaev’s currents with the coupling constants manifestly expressed via the complex coupling constant
η
of the higher-spin theory. It is shown that all currents in the higher-spin theory are conformal in the TT gauge except for those bilinear in the higher-spin gauge fields
ω
.
Turbulent thermal convection was numerically investigated in a cubic cavity under homogeneous and inhomogeneous heating for Rayleigh number Ra=107 and Prandtl number Pr=6.46. Inhomogeneous heating ...was created only at the lower boundary using mixed boundary conditions. Three configurations of the heated regions distribution of the same heating area were considered. The total heat flux through the lower boundary substantially depends on the distribution of the heated regions and increases with decreasing of the heaters size, which is in a good agreement with Ripesi et al., 2014 and Bakhuis et al., 2018. It was found that in turbulent thermal convection under inhomogeneous boundary conditions large-scale circulation (LSC) is formed. Dynamics and structure of LSC strongly depends on the distribution of conducting regions. In case of Rayleigh-Bénard convection, the main flow is more complex with higher-order modes prevailing. Time-averaged velocity field revealed the existence of two vortex rings rotating in opposite directions and located near horizontal walls. Decomposing the velocity into free-slip modes allowed us to find that these vortex rings are stable and provide the most of system energy. The absence of mean LSC results in a specific convective heat transfer mechanism when mean and turbulent heat fluxes are spatially separated.
Magnetic ground state of FeSe Wang, Qisi; Shen, Yao; Pan, Bingying ...
Nature communications,
07/2016, Letnik:
7, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Elucidating the nature of the magnetism of a high-temperature superconductor is crucial for establishing its pairing mechanism. The parent compounds of the cuprate and iron-pnictide superconductors ...exhibit Néel and stripe magnetic order, respectively. However, FeSe, the structurally simplest iron-based superconductor, shows nematic order (Ts=90 K), but not magnetic order in the parent phase, and its magnetic ground state is intensely debated. Here we report inelastic neutron-scattering experiments that reveal both stripe and Néel spin fluctuations over a wide energy range at 110 K. On entering the nematic phase, a substantial amount of spectral weight is transferred from the Néel to the stripe spin fluctuations. Moreover, the total fluctuating magnetic moment of FeSe is ∼60% larger than that in the iron pnictide BaFe2As2. Our results suggest that FeSe is a novel S=1 nematic quantum-disordered paramagnet interpolating between the Néel and stripe magnetic instabilities.
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