We report on the observation of thermal photons from an accelerated electron via examination of radiative beta decay of free neutrons measured by the RDK II collaboration. The emitted photon spectrum is shown to corroborate a thermal distribution consistent with the dynamical Casimir effect. Supported by a robust chi-squared statistic, we find the photons reside in a 1D Planck spectrum with a temperature predicted by the moving mirror model. Subject Indices: B50 (Electromagnetic processes and properties), D29 (Nuclear decays and radioactivities (including fission)), and E76 (Quantum field theory on curved space)

Thermal radiation is found from a moving point charge along a special, globally defined, continuous accelerated trajectory. The calculation is entirely classical (despite the appearance of ℏ) but is shown to have an immediate connection to quantum field theory via the moving mirror model. A precise recipe is given for the functional mathematical identity of the electron–mirror duality that allows one to map between (1) the classical radiation of an ordinary accelerating point charge in 3+1 Minkowski spacetime and (2) the quantum radiation of a moving mirror in 1+1 flat spacetime, for a given rectilinear trajectory.

Non-Abelian flux tubes (strings) are well studied in $\mathcal{N}=2$ supersymmetric QCD in ($3+1$) dimensions. In addition to translational zero modes they have also orientational moduli associated with rotations of their fluxes inside a non-Abelian group. The dynamics of the orientational moduli is described by the two-dimensional $CP(N-1)$ model living on the world sheet of the non-Abelian string. In this paper we consider a deformation of $\mathcal{N}=2$ supersymmetric QCD with the $\mathrm{U}(N)$ gauge group and $N_f=N$ quark flavors with a mass term $\mu$ of the adjoint matter. In the limit of large $\mu$ the theory flows to an $\mathcal{N}=1$ supersymmetric QCD. We study the solution for the non-Abelian string in this limit and derive an effective theory on the string world sheet. The bosonic sector of this theory is still given by the $CP(N-1)$ model but its scale is exponentially small as compared to the scale of the four-dimensional bulk theory in contrast to the $\mathcal{N}=2$ case where these scales are equal. We study also the fermionic sector of the world sheet theory. Upon the deformation, the non-Abelian string is no longer Bogomol’nyi-Prasad-Sommerfield (BPS) state and we show that the fermionic superorientational zero modes are all lifted. This leaves us with the pure bosonic $CP(N-1)$ model on the string world sheet in the limit of $\mathcal{N}=1$ QCD. We also discuss what happens to confined monopoles at large $\mu$.

We study non-Abelian vortex strings in four-dimensional (4D) $\mathcal{N}=2$ supersymmetric QCD with the $\mathrm{U}(N=2)$ gauge group and $N_f=4$ flavors of quark hypermultiplets. It has recently been shown that these vortices behave as critical superstrings. The spectrum of closed string states in the associated string theory was found and interpreted as a spectrum of hadrons in 4D $\mathcal{N}=2$ supersymmetric QCD. In particular, the lowest string state appears to be a massless Bogomol’nyi-Prasad-Sommerfield (BPS) “baryon.” Here we show the occurrence of this stringy baryon using a purely field-theoretic method. To this end we study the conformal world-sheet theory on the non-Abelian string—the so-called weighted $\mathcal{N}=(2,2)$ supersymmetric $\mathbb{C}\mathbb{P}$ model. Its target space is given by the six-dimensional noncompact Calabi-Yau space $Y_6$, the conifold. We use a mirror description of the model to study the BPS kink spectrum and its transformations on curves (walls) of marginal stability. Then we use the 2D-4D correspondence to show that the deformation of the complex structure of the conifold is associated with the emergence of a nonperturbative Higgs branch in 4D theory which opens up at strong coupling. The modulus parameter on this Higgs branch is the vacuum expectation value of the massless BPS baryon previously found in string theory.

It has been shown that non-Abelian vortex string supported in four-dimensional (4D) $\mathcal{N}=2$ supersymmetric QCD (SQCD) with the U(2) gauge group and $N_f=4$ quark flavors becomes a critical superstring. This string propagates in the ten-dimensional space formed by a product of the flat 4D space and an internal space given by a Calabi-Yau noncompact threefold, namely, the conifold. The spectrum of closed string states of the associated string theory was obtained using the equivalence between the critical string on the conifold and the noncritical string on the semi-infinite cigar described by the $\mathrm{SL}(2,\mathbb{R})/U(1)$ Wess-Zumino-Novikov-Witten model. This spectrum was identified with the spectrum of hadrons in 4D $\mathcal{N}=2$ SQCD. In order to describe effective interactions of these 4D hadrons in this paper, we study correlation functions of normalizable vertex operators localized near the tip of the $\mathrm{SL}(2,\mathbb{R})/\mathrm{U}(1)$ cigar. We also compare our solitonic string approach to the gauge-string duality to the AdS/CFT-type holography for little string theories. The latter relates off mass-shell correlation functions on the field theory side to correlation functions of non-normalizable vertex operators on the cigar. We show that in most channels the holographic approach works in our theory because normalizable and non-normalizable vertex operators with the same conformal dimension are related due to the reflection from the tip of the cigar. However, we find that holography does not work for lightest hadrons with given baryonic charge.