Arbitrary Integer Spin Research Articles

[formula omitted] higher-spin supercurrents

We have constructed conserved N=2 higher-spin supercurrents for an arbitrary integer spin through the unconstrained superfield formulation of 4D,N=2 massless higher-spin theories in the harmonic superspace. The obtained supercurrents are gauge-invariant and determine consistent cubic interactions in the gauge superfield × supercurrent form for massless spin s1 and two massless spin s2N=2 supermultiplets. Such interactions and N=2 supercurrents exist only for s1≥2s2. These supercurrents are the N=2 supersymmetric extension of Berends-Burgers-van Dam higher-spin currents and generalize the linearized Bel-Robinson tensor. The relevant N=2 supercurrents can be considered as the descendants of the N=2 principle supercurrent, which has a simple universal structure. An important feature of our outcomes is that, ultimately, all N=2 supercurrents are built from the N=2 superfield strengths, which are constructed from the unconstrained analytical higher-spin prepotentials.

Deriving interaction vertices in higher derivative theories

We derive cubic interaction vertices for a class of higher-derivative theories involving three arbitrary integer spin fields. This derivation uses the requirement of closure of the Poincaré algebra in four-dimensional flat spacetime. We find two varieties of permitted structures at the cubic level and eliminate one variety, which is proportional to the equations of motion, using suitable field redefinitions. We then consider soft theorems for field theories with these higher-derivative interactions and construct amplitudes in these theories using the inverse-soft approach.

On correlation functions of higher-spin currents in arbitrary dimensions d > 3

We revisit the problem of classification and explicit construction of the conformal three-point correlation functions of currents of arbitrary integer spin in arbitrary dimensions. For the conserved currents, we set up the equations for the conservation conditions and solve them completely for some values of spins, confirming the earlier counting of the number of independent structures matching them with the higher-spin cubic vertices in one higher dimension. The general solution for the correlators of conserved currents we delegate to a follow-up work.

On auxiliary fields and Lagrangians for relativistic wave equations

We address the problem of the existence of a Lagrangian for a given system of linear partial differential equation with constant coefficients. As a subtask, this involves bringing the system into a pre-Lagrangian form, wherein the number of equations matches the number of unknowns. We introduce a class of overdetermined systems, called co-flat, and show that they always admit a pre-Lagrangian form, which can be explicitly constructed by means of auxiliary variables. Moreover, we argue that such systems enjoy pre-Lagrangian formulations without auxiliary variables at all. As an application of our method, we construct new pre-Lagrangian and Lagrangian formulations for free massive fields of arbitrary integer spin. In contrast to the well-known models of Singh and Hagen, our Lagrangians involve much fewer auxiliary fields.

Black hole horizon edge partition functions

We extend a formula for 1-loop black hole determinants by Denef, Hartnoll, and Sachdev (DHS) to spinning fields on any (d + 1)-dimensional static spherically symmetric black hole. By carefully analyzing the regularity condition imposed on the Euclidean eigenfunctions, we reveal an unambiguous bulk-edge split in the 1-loop Euclidean partition function for tensor fields of arbitrary integer spin: the bulk part captures the “renormalized” thermal canonical partition function recently discussed in [1]; the edge part is related to quasinormal modes (QNMs) that fail to analytically continue to a subset of Euclidean modes with enhanced fall-offs near the origin. Since the edge part takes the form of a path integral on Sd−1, this suggests that these are associated with degrees of freedom living on the bifurcation surface in the Lorentzian two-sided black hole geometry. For massive higher spin on static BTZ and massive vector on Nariai black holes, we find that the edge partition function is related to the QNMs with lowest overtone numbers.

Eikonal approximation in celestial CFT

We identify an eikonal regime in celestial CFT2 in which massless 2-2 scattering is dominated by t-channel exchange. We derive a formula for the celestial amplitude that resums exchanges of arbitrary integer spin to all orders in the coupling. The resulting eikonal phase takes the same form as in flat space with the powers of center-of-mass energy replaced by weight-shifting operators on the celestial sphere. We independently compute the celestial two-point function for a scalar propagating in a shockwave background and show that to leading order in the gravitational coupling and for a suitable choice of the source, the result agrees with the prediction from the celestial eikonal formula for graviton exchange. We demonstrate that this two-point function can be directly obtained from the corresponding formula in AdS4 in a flat space limit. We finally establish a general relation between scalar celestial amplitudes in celestial CFTd−1 and the flat space limit of scalar AdSd+1 Witten diagrams.

Interacting massive and massless arbitrary spin fields in 4d flat space

Massive and massless arbitrary integer spin fields propagating in four-dimensional flat space are studied. The massive and massless fields are treated by using a light-cone gauge helicity basis formalism. Cubic cross-interactions between massive and massless fields and cubic interactions between massive fields are investigated. We introduce a classification of such cubic interactions and using our classification we build all cubic interaction vertices. Realization of generators of the Poincaré algebra on space of interacting fields is found. As a by-product, some illustrative examples of light-cone form for 3-point invariant amplitudes of massive and massless fields are also discussed.

On massive higher spins in d = 3

In this paper we consider a frame-like gauge invariant description of massive higher spin bosons and fermions in d = 3 and provide for the first time a proof that such formulation does describe just one massive physical degree of freedom with the appropriate helicity. For this purpose we completely fix all the gauge symmetries and show that all other auxiliary components vanish on-shell, while the only remaining highest component satisfies the correct equations. As a bonus, we show that the Lagrangians for the so-called self-dual massive spin-3 and spin-4 fields proposed by Aragone and Khoudeir (as well as their generalization to arbitrary integer and half-integer spins) can be obtained from the gauge invariant ones by the appropriate gauge fixing.

The band structure of the whole spectrum of an N-body cold system containing atoms with arbitrary integer spin and dominated by singlet pairing force

The spectra of N-boson systems with arbitrary nonzero spin have been studied. Firstly, only the singlet pairing interaction is considered, a set of exact eigenstates together with the eigenenergies are analytically obtained. The completeness of this set is proved. The analytical expression allows us to see clearly the spin textures of various states different in N and/or , and to find out the similarity and relationship lying among them. Secondly, the effect of other interactions is evaluated via exact numerical calculations on the systems with a smaller N. Some features and notable phenomena that might emerge in high- systems, say, the ground band might have extremely high level density, have been discussed.

Off-shell higher-spin fields in AdS4 and external currents

We construct an unfolded system for off-shell fields of arbitrary integer spin in 4d anti-de Sitter space. To this end we couple an on-shell system, encoding Fronsdal equations, to external Fronsdal currents for which we find an unfolded formulation. We present a reduction of the Fronsdal current system which brings it to the unfolded Fierz-Pauli system describing massive fields of arbitrary integer spin. Reformulating off-shell higher-spin system as the set of Schwinger–Dyson equations we compute propagators of higher-spin fields in the de Donder gauge directly from the unfolded equations. We discover operators that significantly simplify this computation, allowing a straightforward extraction of wave equations from an unfolded system.

A compendium of sphere path integrals

We study the manifestly covariant and local 1-loop path integrals on Sd+1 for general massive, shift-symmetric and (partially) massless totally symmetric tensor fields of arbitrary spin s ≥ 0 in any dimensions d ≥ 2. After reviewing the cases of massless fields with spin s = 1, 2, we provide a detailed derivation for path integrals of massless fields of arbitrary integer spins s ≥ 1. Following the standard procedure of Wick-rotating the negative conformal modes, we find a higher spin analog of Polchinski’s phase for any integer spin s ≥ 2. The derivations for low-spin (s = 0, 1, 2) massive, shift-symmetric and partially massless fields are also carried out explicitly. Finally, we provide general prescriptions for general massive and shift-symmetric fields of arbitrary integer spins and partially massless fields of arbitrary integer spins and depths.

Higher spin analogs of linearized topologically massive gravity and linearized new massive gravity

We suggest a new spin-4 self-dual model (parity singlet) and a new spin-4 parity doublet in $D=2+1$. They are of higher order in derivatives and are described by a totally symmetric rank-4 tensor without extra auxiliary fields. Despite the higher derivatives they are ghost free. We find gauge invariant field combinations which allow us to show that the canonical structure of the spin-4 (spin-3) models follows the same pattern of its spin-2 (spin-1) counterpart after field redefinitions. For $s=1$, 2, 3, 4, the spin-$s$ self-dual models of order $2s\ensuremath{-}1$ and the doublet models of order $2s$ can be written in terms of three gauge invariants. The cases $s=3$ and $s=4$ suggest a restricted conformal higher spin symmetry as a principle for defining linearized topologically massive gravity and linearized ``new massive gravity'' for arbitrary integer spins. A key role in our approach is played by the fact that the Cotton tensor in $D=2+1$ has only two independent components for any integer spin.

Self-dual models in [formula omitted] from dimensional reduction

Here we perform a Kaluza–Klein dimensional reduction of Vasiliev’s first-order description of massless spin-s particles from D=3+1 to D=2+1 and derive first-order self-dual models describing particles with helicities ±s for the cases s=1,2,3. In the first two cases we recover known (parity singlets) self-dual models. In the spin-3 case we derive a new first order self-dual model with a local Weyl symmetry which lifts the traceless restriction on the rank-3 tensor. A gauge fixed version of this model corresponds to a known spin-3 self-dual model. We conjecture that our procedure can be generalized to arbitrary integer spins.

AdS (super)projectors in three dimensions and partial masslessness

We derive the transverse projection operators for fields with arbitrary integer and half-integer spin on three-dimensional anti-de Sitter space, AdS3. The projectors are constructed in terms of the quadratic Casimir operators of the isometry group SO(2, 2) of AdS3. Their poles are demonstrated to correspond to (partially) massless fields. As an application, we make use of the projectors to recast the conformal and topologically massive higher-spin actions in AdS3 into a manifestly gauge-invariant and factorised form. We also propose operators which isolate the component of a field that is transverse and carries a definite helicity. Such fields correspond to irreducible representations of SO(2, 2). Our results are then extended to the case of mathcal{N} = 1 AdS3 supersymmetry.

The σ− Cohomology Analysis for Symmetric Higher-Spin Fields

In this paper, we present a complete proof of the so-called First On-Shell Theorem that determines dynamical content of the unfolded equations for free symmetric massless fields of arbitrary integer spin in any dimension and arbitrary integer or half-integer spin in four dimensions. This is achieved by calculation of the respective σ− cohomology both in the tensor language in Minkowski space of any dimension and in terms of spinors in AdS4. In the d-dimensional case Hp(σ−) is computed for any p and interpretation of Hp(σ−) is given both for the original Fronsdal system and for the associated systems of higher form fields.

Efficient and accurate gradient flow methods for computing ground states of spinor Bose-Einstein condensates

An accurate and efficient normalized gradient flow (NGF) method is developed to compute the ground state of a spinor Bose-Einstein condensate (BEC) with an arbitrary positive integer spin, which is described as a vector wave function that minimizes the Gross-Pitaevskii energy functional under the two constraints of the total mass and magnetization. Similar to the NGF for computing the ground states of single component BEC, the proposed method consists of two steps, i.e. the gradient flow part to decrease the energy and the projection step for the mass and magnetization constraints. By introducing the Lagrange multipliers in the gradient flow part, the constructed method allows various possible temporal discretizations and inexact projections could be applied in the projection steps. Specifically, we adopt a semi-implicit Euler time discretization scheme to discretize the gradient flow with Lagrange multipliers, thus only a completely decoupled linear elliptic system with constant coefficients needs to be solved at each time step. Moreover, two simple inexact projection methods are proposed and analyzed. Finally, the numerical results for spin-1, spin-2 and spin-3 cases are presented to show the accuracy and effectiveness of our algorithm, and the numerical comparisons for different choices of projections are reported.

Massive spinning bosons on the celestial sphere

A natural extension of the Pasterski-Shao-Strominger (PSS) prescription is described, enabling the map of Minkowski space amplitudes with massive spinning external legs to the celestial sphere to be performed. An integral representation for the conformal primary wave function (CPW) of massive spinning bosons on the celestial sphere is derived explicitly for spin-one and -two. By analogy with the spin-zero case, the spinning bulk-to-boundary propagator on Euclidean AdS is employed to extend the massive CPW integral representation to arbitrary integer spin, and to describe the appropriate inverse transform of massive spinning CPWs back to the plane wave basis in Minkowski space. Subsequently, a massive spin-s momentum operator representation on the celestial sphere is determined, and used in conjunction with known Lorentz generators to derive Poincaré symmetry constraints on generic massive spinning two-, three- and four-point celestial amplitude structures. Finally, as a consistency check, three-point Minkowski space amplitudes of two massless scalars and a spin-one or -two massive boson are explicitly mapped to the celestial sphere, and the resulting three-point function coefficients are confirmed to be in exact agreement with the results obtained from Poincaré symmetry constraints.

Non-Abelian anomalies in multi-Weyl semimetals

We construct the effective field theory for time-reversal symmetry breaking multi-Weyl semimetals (mWSMs), composed of a single pair of Weyl nodes of (anti-)monopole charge $n$, with $n=1,2,3$ in crystalline environment. From both the continuum and lattice models, we show that a mWSM with $n>1$ can be constructed by placing $n$ flavors of linearly dispersing simple Weyl fermions (with $n=1$) in a bath of an $SU(2)$ non-Abelian static background gauge field. Such an $SU(2)$ field preserves certain crystalline symmetry (four-fold rotational or $C_4$ in our construction), but breaks the Lorentz symmetry, resulting in nonlinear band spectra (namely, $E \sim (p^2_x + p^2_y)^{n/2}$, but $E \sim |p_z|$, for example, where momenta ${\bf p}$ is measured from the Weyl nodes). Consequently, the effective field theory displays $U(1) \times SU(2)$ non-Abelian anomaly, yielding anomalous Hall effect, its non-Abelian generalization, and various chiral conductivities. The anomalous violation of conservation laws is determined by the monopole charge $n$ and a specific algebraic property of the $SU(2)$ Lie group, which we further substantiate by numerically computing the regular and "isospin" densities from the lattice models of mWSMs. These predictions are also supported from a strongly coupled (holographic) description of mWSMs. Altogether our findings unify the field theoretic descriptions of mWSMs of arbitrary monopole charge $n$ (featuring $n$ copies of the Fermi arc surface states), predict signatures of non-Abelian anomaly in table-top experiments, and pave the route to explore anomaly structures for multi-fold fermions, transforming under arbitrary half-integer or integer spin representations.

Ground States of Spin-$F$ Bose--Einstein Condensates

The computation of the ground states of spin-$F$ Bose--Einstein condensates (BECs) can be formulated as an energy minimization problem with two quadratic constraints. We discretize the energy functional and constraints using the Fourier pseudospectral schemes and view the discretized problem as an optimization problem on manifold. Three different types of retractions to the manifold are designed. They enable us to apply various optimization methods on manifold to solve the problem. Specifically, an adaptive regularized Newton method is used together with a cascadic multigrid technique to accelerate the convergence. Our method is the first applicable algorithm for BECs with an arbitrary integer spin, including the complicated spin-3 BECs. Extensive numerical results on ground states of spin-1, spin-2, and spin-3 BECs with diverse interaction and optical lattice potential in one/two/three dimensions are reported to show the efficiency of our method and to demonstrate interesting physical phenomena.

Generalized triple-component fermions: Lattice model, Fermi arcs, and anomalous transport

We generalize the construction of time-reversal symmetry-breaking triple-component semimetals, transforming under the pseudospin-1 representation, to arbitrary (anti-)monopole charge $2 n$, with $n=1,2,3$ in the crystalline environment. The quasiparticle spectra of such systems are composed of two dispersing bands with pseudospin projections $m_s=\pm 1$ and energy dispersions $E_{\bf k}=\pm \sqrt{ \alpha^2_n k^{2n}_\perp +v^2_z k^2_z}$, where $k_\perp=\sqrt{k^2_x+k^2_y}$, and one completely flat band at zero energy with $m_s=0$. We construct simple tight-binding models for such spin-1 excitations on a cubic lattice and address the symmetries of the generalized triple-component Hamiltonian. In accordance to the bulk-boundary correspondence, triple-component semimetals support $2 n$ branches of topological Fermi arc surface states and also accommodate a \emph{large} anomalous Hall conductivity (in the $xy$ plane), given by $\sigma^{\rm 3D}_{xy} \propto 2 n \times$ the separation of the triple-component nodes (in units of $e^2/h$). Furthermore, we compute the longitudinal magnetoconductivity, planar Hall conductivity, and magneto thermal conductivity in these systems, which increase as $B^2$ for sufficiently weak magnetic fields ($B$) due to the nontrivial Berry curvature in the medium. A generalization of our construction to arbitrary integer spin systems is also highlighted.