Renormalization Group Improvement and Dynamical Breaking of Symmetry in a Supersymmetric Chern-Simons-matter Model

In this work, we investigate the consequences of the Renormalization Group Equation (RGE) in the determination of the effective superpotential and the study of Dynamical Symmetry Breaking (DSB) in an N = 1 supersymmetric theory including an Abelian Chern-Simons superfield coupled to N scalar superfields in (2+1) dimensional spacetime. The classical Lagrangian presents scale invariance, which is broken by radiative corrections to the effective superpotential. We calculate the effective superpotential up to two-loops by using the RGE and the beta functions and anomalous dimensions known in the literature. We then show how the RGE can be used to improve this calculation, by summing up properly defined series of leading logs (LL), next-to-leading logs (NLL) contributions, and so on... We conclude that even if the RGE improvement procedure can indeed be applied in a supersymmetric model, the effects of the consideration of the RGE are not so dramatic as it happens in the non-supersymmetric case.Comment: v4: 11 pages, 1 figure. Version accepted for publication in NP

Non-perturbative fixed points and renormalization group improved effective potential

The stability conditions of a renormalization group improved effective potential have been discussed in the case of scalar QED and QCD with a colorless scalar. We calculate the same potential in these models assuming the existence of non-perturbative fixed points associated to a conformal phase. In the case of scalar QED the barrier of instability found previously is barely displaced as we approach the fixed point, and in the case of QCD with a colorless scalar not only the barrier is changed but the local minimum of the potential is also changed.Comment: 6 pages, 8 figures, References added. Matching the journal versio

Characterization of periodic cavitation in an optical tweezer

Microscopic vapor explosions or cavitation bubbles can be generated periodically in an optical tweezer with a microparticle that partially absorbs at the trapping laser wavelength. In this work we measure the size distribution and the production rate of cavitation bubbles for microparticles with a diameter of 3 $\mu$m using high speed video recording and a fast photodiode. We find that there is a lower bound for the maximum bubble radius $R_{max}\sim 2~\mu$m which can be explained in terms of the microparticle size. More than $94 \%$ of the measured $R_{max}$ are in the range between 2 and 6 $\mu$m, while the same percentage of the measured individual frequencies $f_i$ or production rates are between 10 and 200 Hz. The photodiode signal yields an upper bound for the lifetime of the bubbles, which is at most twice the value predicted by the Rayleigh equation. We also report empirical relations between $R_{max}$, $f_i$ and the bubble lifetimes.Comment: 5 pages, 3 figure

Interferometric measurement of arbitrary propagating vector beams that are tightly focused

In this work we demonstrate a simple setup to generate and measure arbitrary vector beams that are tightly focused. The vector beams are created with a spatial light modulator and focused with a microscope objective with an effective numerical aperture of 1.2. The transverse polarization components ($E_x$, $E_y$) of the tightly focused vector beams are measured with 3 step interferometry. The axial component $E_z$ is reconstructed using the transverse fields with Gauss law. We measure beams with the following polarization states: circular, radial, azimuthal, spiral, flower and spider web.Comment: 4 pages, 4 figure

DEVELOPING ENTREPRENEURSHIP IN DIGITAL ECONOMY: THE ECOSYSTEM STRATEGY FOR STARTUPS GROWTH

The transition of the economies towards the digital economy is determining the arising of a type of entrepreneurship based on factors and characteristics widely different from traditional game rules. These changes disclose a series of opportunities for those firms which will be able to adapt at the new parameters and functionalities related to digital technologies diffusion. This contribution underlines some dynamics that should be considered from policy makers who aspire, on the one hand, to promote the emergence of a significant number of startups operating in the digital field and, on the other hand, to nurture the growth process of startups into scale ups. Due to social and economic troubles of many western areas, this latter aspect is even more important. According to a flourishing research stream on entrepreneurship, an interpretative approach to achieving the dual objective is to implement a specific strategy to create an appropriate regional ecosystem. This ecosystem represents a clear change within entrepreneurial policies frame, whose results have so far often been unsatisfactory. Despite its initially selective approach, from an ecosystem many potential benefits can descend. However, creating an ecosystem for digital startup is a complex and burdensome task, which requires a safe and competent guidance, as well as the active involvement of many local actors

Isotopic difference in the heteronuclear loss rate in a two-species surface trap

We have realized a two-species mirror-magneto-optical trap containing a mixture of $^{87}$Rb ($^{85}$Rb) and $^{133}$Cs atoms. Using this trap, we have measured the heteronuclear collisional loss rate $\beta_{Rb-Cs}'$ due to intra-species cold collisions. We find a distinct difference in the magnitude and intensity dependence of $\beta_{Rb-Cs}'$ for the two isotopes $^{87}$Rb and $^{85}$Rb which we attribute to the different ground-state hyperfine splitting energies of the two isotopes.Comment: 4 pages, 2 figure