Error-Disturbance Uncertainty Relations in Neutron-Spin Measurements

In his seminal paper, which was published in 1927, Heisenberg originally introduced a relation between the precision of a measurement and the disturbance it induces onto another measurement. Here, we report a neutron-optical experiment that records the error of a spin-component measurement as well as the disturbance caused on a measurement of another spin-component to test error-disturbance uncertainty relations (EDRs). We demonstrate that Heisenberg’s original EDR is violated and the Ozawa and Branciard EDRs are valid in a wide range of experimental parameters

Flat space (higher spin) gravity with chemical potentials

We introduce flat space spin-3 gravity in the presence of chemical potentials and discuss some applications to flat space cosmology solutions, their entropy, free energy and flat space orbifold singularity resolution. Our results include flat space Einstein gravity with chemical potentials as special case. We discover novel types of phase transitions between flat space cosmologies with spin-3 hair and show that the branch that continuously connects to spin-2 gravity becomes thermodynamically unstable for sufficiently large temperature or spin-3 chemical potential

Lifshitz holography with isotropic scale invariance

Is it possible for an anisotropic Lifshitz critical point to actually exhibit isotropic conformal invariance? We answer this question in the affirmative by constructing a concrete holographic realization. We study three-dimensional spin-3 higher-spin gauge theory with a z = 2 Lifshitz ground state with non-trivial spin-3 background. We provide consistent boundary conditions and determine the associated asymptotic symmetry algebra. Surprisingly, we find that the algebra consists of two copies of the W 3 $${\mathcal{W}}_3$$ extended conformal algebra, which is the extended conformal algebra of an isotropic critical system. Moreover, the central charges are given by 3 ℓ/ (2 G ). We consider the possible geometric interpretation of the theory in light of the higher spin gauge invariance and remark on the implications of the asymptotic symmetry analysis

Interacting spin-2 fields in three dimensions

Using the frame formulation of multi-gravity in three dimensions, we show that demanding the presence of secondary constraints which remove the Boulware-Deser ghosts restricts the possible interaction terms of the theory and identifies invertible frame field combinations whose effective metric may consistently couple to matter. The resulting ghost-free theories can be represented by theory graphs which are trees. In the case of three frame fields, we explicitly show that the requirement of positive masses and energies for the bulk spin-2 modes in AdS 3 is consistent with a positive central charge for the putative dual CFT 2

On the energy-momentum tensor in Moyal space

We study the properties of the energy-momentum tensor of gauge fields coupled to matter in non-commutative (Moyal) space. In general, the non-commutativity affects the usual conservation law of the tensor as well as its transformation properties (gauge covariance instead of gauge invariance). It is well known that the conservation of the energy-momentum tensor can be achieved by a redefinition involving another star-product. Furthermore, for a pure gauge theory it is always possible to define a gauge invariant energy-momentum tensor by means of a Wilson line. We show that the last two procedures are incompatible with each other if couplings of gauge fields to matter fields (scalars or fermions) are considered: The gauge invariant tensor (constructed via Wilson line) does not allow for a redefinition assuring its conservation, and vice versa the introduction of another star-product does not allow for gauge invariance by means of a Wilson line

Logarithmic AdS waves and Zwei-Dreibein gravity

We show that the parameter space of Zwei-Dreibein Gravity (ZDG) in AdS 3 exhibits critical points, where massive graviton modes coincide with pure gauge modes and new ‘logarithmic’ modes appear, similar to what happens in New Massive Gravity. The existence of critical points is shown both at the linearized level, as well as by finding AdS wave solutions of the full non-linear theory, that behave as logarithmic modes towards the AdS boundary. In order to find these solutions explicitly, we give a reformulation of ZDG in terms of a single Dreibein, that involves an infinite number of derivatives. At the critical points, ZDG can be conjectured to be dual to a logarithmic conformal field theory with zero central charges, characterized by new anomalies whose conjectured values are calculated

Unitary W-algebras and three-dimensional higher spin gravities with spin one symmetry

We investigate whether there are unitary families of W-algebras with spin one fields in the natural example of the Feigin-Semikhatov $W_n^{(2) }$ -algebra. This algebra is conjecturally a quantum Hamiltonian reduction corresponding to a non-principal nilpotent element. We conjecture that this algebra admits a unitary real form for even n . Our main result is that this conjecture is consistent with the known part of the operator product algebra, and especially it is true for n = 2 and n = 4. Moreover, we find certain ranges of allowed levels where a positive definite inner product is possible. We also find a unitary conformal field theory for every even n at the special level k + n = ( n + 1) / ( n − 1). At these points, the $W_n^{(2) }$ -algebra is nothing but a compactified free boson. This family of W-algebras admits an ’t Hooft limit. Further, in the case of n = 4, we reproduce the algebra from the higher spin gravity point of view. In general, gravity computations allow us to reproduce some leading coefficients of the operator product

Calculating the chiral condensate of QCD at infinite coupling using a generalised lattice diagrammatic approach

We develop a lattice diagrammatic technique for calculating the chiral condensate of QCD at infinite coupling inspired by recent work of Tomboulis and earlier work from the 80’s. The technique involves calculating the contribution of gauge link diagrams formed from all possible combinations of a truncated number of sub-diagram types, by performing a resummation. We show how to calculate the relevant sub-diagrams, including a new technique for evaluating group integrals with arbitrary number of gauge link elements, using Young Projectors. Including up to four different diagram types we calculate the chiral condensate as a function of N f , and show that two real solutions result, which are non-zero for all integer N f . We analyse these solutions and find signs of convergence of the expansion at small N f . We should stress that a drawback of our technique is that, due to the addition of non-tree diagrams in the resummation, there are sources of error associated with miscounting and over-counting of diagrams. We discuss these sources of error in de- tail, and implement a technique to reduce over-counting of diagrams, while leaving other sources of error for future work

Direct detection constraints on dark photon dark matter

Dark matter detectors built primarily to probe elastic scattering of WIMPs on nuclei are also precise probes of light, weakly coupled, particles that may be absorbed by the detector material. In this paper, we derive constraints on the minimal model of dark matter comprised of long-lived vector states V (dark photons) in the 0.01– 100 keV mass range. The absence of an ionization signal in direct detection experiments such as XENON10 and XENON100 places a very strong constraint on the dark photon mixing angle, down to O(10−15) , assuming that dark photons comprise the dominant fraction of dark matter. This sensitivity to dark photon dark matter exceeds the indirect bounds derived from stellar energy loss considerations over a significant fraction of the available mass range. We also revisit indirect constraints from V→3γ decay and show that limits from modifications to the cosmological ionization history are comparable to the updated limits from the diffuse γ -ray flux

Search for B decays to final states with the η c meson

We report a search for B decays to selected final states with the η c meson: B ± → K ± η c π + π − , B ± → K ± η c ω , B ± → K ± η c η and B ± → K ± η c π 0 . The analysis is based on 772 × 10 6 B B ¯ $$B\overline{B}$$ pairs collected at the Υ(4 S ) resonance with the Belle detector at the KEKB asymmetric-energy e + e − collider. We set 90% confidence level upper limits on the branching fractions of the studied B decay modes, independent of intermediate resonances, in the range (0 . 6–5 . 3) × 10 −4 . We also search for molecular-state candidates in the D 0 D ¯ ∗ 0 − D ¯ 0 D ∗ 0 , D 0 D ¯ 0 + D ¯ 0 D 0 $${D}^0{\overline{D}}^{\ast 0}-{\overline{D}}^0{D}^{\ast 0},{D}^0{\overline{D}}^0+{\overline{D}}^0{D}^0$$ and D ∗ 0 D ¯ ∗ 0 + D ¯ ∗ 0 D ∗ 0 $${D}^{\ast 0}{\overline{D}}^{\ast 0}+{\overline{D}}^{\ast 0}{D}^{\ast 0}$$ combinations, neutral partners of the Z (3900) ± and Z (4020) ± , and a poorly understood state X (3915) as possible intermediate states in the decay chain, and set 90% confidence level upper limits on the product of branching fractions to the mentioned intermediate states and decay branching fractions of these states in the range (0 . 6–6 . 9) × 10 −5