Metastable nonconfining states in SU(3) lattice gauge theory with sextet fermions

We study the SU(3) lattice gauge theory, with two flavors of sextet Wilson-clover fermions, near its finite-temperature phase transition. We find metastable states that have Wilson line expectation values whose complex phases are near 2pi/3 or pi. The true equilibrium phase at these couplings and temperatures has its Wilson line oriented only towards the positive real axis, in agreement with perturbation theory.Comment: 14 pages, 9 figures; added a referenc

Universal Dimer in a Collisionally Opaque Medium: Experimental Observables and Efimov Resonances

A universal dimer is subject to secondary collisions with atoms when formed in a cloud of ultracold atoms via three-body recombination. We show that in a collisionally opaque medium, the value of the scattering length that results in the maximum number of secondary collisions may not correspond to the Efimov resonance at the atom-dimer threshold and thus can not be automatically associated with it. This result explains a number of controversies in recent experimental results on universal three-body states and supports the emerging evidence for the significant finite range corrections to the first excited Efimov energy level.Comment: 5 pages, 2 figure

Three-body recombination at vanishing scattering lengths in an ultracold Bose gas

We report on measurements of three-body recombination rates in an ultracold gas of $^7$Li atoms in the extremely nonuniversal regime where the two-body scattering length vanishes. We show that the rate is well defined and can be described by two-body parameters only: the scattering length $a$ and the effective range $R_e$. We find the rate to be energy independent, and, by connecting our results with previously reported measurements in the universal limit, we cover the behavior of the three-body recombination in the whole range from weak to strong two-body interactions. We identify a nontrivial magnetic field value in the nonuniversal regime where the rate should be strongly reduced.Comment: Version with enhanced supplemental material

The Crystal Structure of Nitrosomonas Europaea Sucrose Synthase Reveals Critical Conformational Changes and Insights into the Sucrose Metabolism in Prokaryotes

In this paper we report the first crystal structure of a prokaryotic sucrose synthase from the non-photosynthetic bacterium Nitrosomonas europaea. The obtained structure was in an open form, whereas the only other available structure from the plant Arabidopsis thaliana was in a closed conformation. Comparative structural analysis revealed a “hinge-latch” combination, which is critical to transition between the open and closed forms of the enzyme. The N. europaea sucrose synthase shares the same fold as the GT-B family of the retaining glycosyltransferases. In addition, a triad of conserved homologous catalytic residues in the family showed to be functionally critical in the N. europaea sucrose synthase (Arg567, Lys572, Glu663). This implies that sucrose synthase shares not only a common origin with the GT-B family, but also a similar catalytic mechanism. The enzyme preferred transferring glucose from ADP-glucose rather than UDP-glucose like the eukaryotic counterparts. This predicts that these prokaryotic organisms have a different sucrose metabolic scenario from plants. Nucleotide preference determines where the glucose moiety is targeted after sucrose is degraded

Domain Walls and Metastable Vacua in Hot Orientifold Field Theories

We consider "Orientifold field theories", namely SU(N) gauge theories with Dirac fermions in the two-index representation at high temperature. When N is even these theories exhibit a spontaneously broken Z2 centre symmetry. We study aspects of the domain wall that interpolates between the two vacua of the theory. In particular we calculate its tension to two-loop order. We compare its tension to the corresponding domain wall in a SU(N) gauge theory with adjoint fermions and find an agreement at large-N, as expected from planar equivalence between the two theories. Moreover, we provide a non-perturbative proof for the coincidence of the tensions at large-N. We also discuss the vacuum structure of the theory when the fermion is given a large mass and argue that there exist N-2 metastable vacua. We calculate the lifetime of those vacua in the thin wall approximation.Comment: 29 pages, 4 figures. v2: minor changes in the introduction section. to appear in JHE

Study of Efimov physics in two nuclear-spin sublevels of 7Li

Efimov physics in two nuclear-spin sublevels of bosonic lithium is studied and it is shown that the positions and widths of recombination minima and Efimov resonances are identical for both states within the experimental errors which indicates that the short-range physics is nuclear-spin independent. We also find that the Efimov features are universally related across Feshbach resonances. These results crucially depend on careful mapping between the scattering length and the applied magnetic field which we achieve by characterization of the two broad Feshbach resonances in the different states by means of rf-spectroscopy of weakly bound molecules. By fitting the binding energies numerically with a coupled channels calculation we precisely determine the absolute positions of the Feshbach resonances and the values of the singlet and triplet scattering lengths.Comment: 15 pages, 7 figure

Association of Efimov trimers from a three-atom continuum

We develop an experimental technique for rf-association of Efimov trimers from three-atoms continuum. We apply it to probe the lowest accessible Efimov energy level in bosonic lithium in the region where strong deviations from the universal behavior are expected, and provide quantitative study of this effect. Position of the Efimov resonance at the atom-dimer threshold, measured with a different experimental technique, concurs with the rf-association results.Comment: 5 pages, 4 figure

Extreme Technicolor & The Walking Critical Temperature

We map the phase diagram of gauge theories of fundamental interactions in the flavor-temperature plane using chiral perturbation theory to estimate the relation between the pion decaying constant and the critical temperature above which chiral symmetry is restored. We then investigate the impact of our results on models of dynamical electroweak symmetry breaking and therefore on the electroweak early universe phase transition.Comment: RevTeX, 18 pages, 3 figure