Inverse magnetic catalysis and regularization in the quark-meson model

Motivated by recent work on inverse magnetic catalysis at finite temperature, we study the quark-meson model using both dimensional regularization and a sharp cutoff. We calculate the critical temperature for the chiral transition as a function of the Yukawa coupling in the mean-field approximation varying the renormalization scale and the value of the ultraviolet cutoff. We show that the results depend sensitively on how one treats the fermionic vacuum fluctuations in the model and in particular on the regulator used. Finally, we explore a $B$-dependent transition temperature for the Polyakov loop potential $T_0(B)$ using the functional renormalization group. These results show that even arbitrary freedom in the function $T_0(B)$ does not allow for a decreasing chiral transition temperature as a function of $B$. This is in agreement with previous mean-field calculations.Comment: 13 pages, 5 figure

Chiral and deconfinement transitions in a magnetic background using the functional renormalization group with the Polyakov loop

We use the Polyakov loop coupled quark-meson model to approximate low energy QCD and present results for the chiral and deconfinement transitions in the presence of a constant magnetic background $B$ at finite temperature $T$ and baryon chemical potential $\mu_B$. We investigate effects of various gluoni potentials on the deconfinement transition with and without a fermionic backreaction at finite $B$. Additionally we investigate the effect of the Polyakov loop on the chiral phase transition, finding that magnetic catalysis at low $\mu_B$ is present, but weakened by the Polyakov loop.Comment: 17 pages and 8 figs. v2: added ref

Systemic analysis of the response of Aspergillus niger to ambient pH

Systems modeling of Aspergillus niger under different pH conditions reveals novel pH-regulated metabolic genes and signaling genes in the pal/pacC pathway

Screened Perturbation Theory to Three Loops

The thermal physics of a massless scalar field with a phi^4 interaction is studied within screened perturbation theory (SPT). In this method the perturbative expansion is reorganized by adding and subtracting a mass term in the lagrangian. We consider several different mass prescriptions that generalize the one-loop gap equation to two-loop order. We calculate the pressure and entropy to three-loop order and the screening mass to two-loop order. In contrast to the weak-coupling expansion, the SPT-improved approximations appear to converge even for rather large values of the coupling constant.Comment: 30 pages, 10 figure

Bod1, a novel kinetochore protein required for chromosome biorientation

We have combined the proteomic analysis of Xenopus laevis in vitro–assembled chromosomes with RNA interference and live cell imaging in HeLa cells to identify novel factors required for proper chromosome segregation. The first of these is Bod1, a protein conserved throughout metazoans that associates with a large macromolecular complex and localizes with kinetochores and spindle poles during mitosis. Small interfering RNA depletion of Bod1 in HeLa cells produces elongated mitotic spindles with severe biorientation defects. Bod1-depleted cells form syntelic attachments that can oscillate and generate enough force to separate sister kinetochores, suggesting that microtubule–kinetochore interactions were intact. Releasing Bod1-depleted cells from a monastrol block increases the frequency of syntelic attachments and the number of cells displaying biorientation defects. Bod1 depletion does not affect the activity or localization of Aurora B but does cause mislocalization of the microtubule depolymerase mitotic centromere- associated kinesin and prevents its efficient phosphorylation by Aurora B. Therefore, Bod1 is a novel kinetochore protein that is required for the detection or resolution of syntelic attachments in mitotic spindles

Three-loop Phi-derivable Approximation in QED

In this paper we examine Phi-derivable approximations in QED. General theorems tell us that the gauge dependence of the n-loop Phi-derivable approximation shows up at order g^(2n) where g is the coupling constant. We consider the gauge dependence of the two-loop Phi-derivable approximation to the Debye mass and show that it is of order e^4 as expected. We solve the three-loop Phi-derivable approximation in QED by expanding sum-integrals in powers of e^2 and m/T, where m is the Debye mass which satisfies a variational gap equation. The results for the pressure and the Debye mass are accurate to order e^5.Comment: 10 pages, 5 figures. v2: typos corrected and references adde

Four-loop screened perturbation theory

We study the thermodynamics of massless phi-fourth theory using screened perturbation theory. In this method, the perturbative expansion is reorganized by adding and subtracting a thermal mass term in the Lagrangian. We calculate the free energy through four loops expanding in a double power expansion in m/T and g^2, where m is the thermal mass and g is the coupling constant. The expansion is truncated at order g^7 and the loop expansion is shown to have better convergence properties than the weak-coupling expansion. The free energy at order g^6 involves the four-loop triangle sum-integral evaluated by Gynther, Laine, Schroeder, Torrero, and Vuorinen using methods developed by Arnold and Zhai. The evaluation of the free energy at order g^7 requires the evaluation of a nontrivial three-loop sum-integral, which we calculate by the same methods.Comment: 34 pages, 6 figures, RevTe