291 research outputs found
Non-perturbative Test of the Witten-Veneziano Formula from Lattice QCD
We compute both sides of the Witten-Veneziano formula using lattice
techniques. For the one side we perform dedicated quenched simulations and use
the spectral projector method to determine the topological susceptibility in
the pure Yang-Mills theory. The other side we determine in lattice QCD with
dynamical Wilson twisted mass fermions including for the first time
also the flavour singlet decay constant. The Witten-Veneziano formula
represents a leading order expression in the framework of chiral perturbation
theory and we also employ leading order chiral perturbation theory to relate
the flavor singlet decay constant to the relevant decay constant parameters in
the quark flavor basis and flavor non-singlet decay constants. After taking the
continuum and the SU chiral limits we compare both sides and find good
agreement within uncertainties.Comment: 30 pages, 7 figures, version accepted for publicatio
Renormalization of minimally doubled fermions
We investigate the renormalization properties of minimally doubled fermions,
at one loop in perturbation theory. Our study is based on the two particular
realizations of Borici-Creutz and Karsten-Wilczek. A common feature of both
formulations is the breaking of hyper-cubic symmetry, which requires that the
lattice actions are supplemented by suitable counterterms. We show that three
counterterms are required in each case and determine their coefficients to one
loop in perturbation theory. For both actions we compute the vacuum
polarization of the gluon. It is shown that no power divergences appear and
that all contributions which arise from the breaking of Lorentz symmetry are
cancelled by the counterterms. We also derive the conserved vector and
axial-vector currents for Karsten-Wilczek fermions. Like in the case of the
previously studied Borici-Creutz action, one obtains simple expressions,
involving only nearest-neighbour sites. We suggest methods how to fix the
coefficients of the counterterms non-perturbatively and discuss the
implications of our findings for practical simulations.Comment: 23 pages, 1 figur
Short distance singularities and automatic O(a) improvement: the cases of the chiral condensate and the topological susceptibility
Congenital and Acquired Chronic Neutropenias: Challenges, Perspectives and Implementation of the EuNet-INNOCHRON Action
Does VO2 Host a Transient Monoclinic Metallic Phase?
Ultrafast phase transitions induced by femtosecond light pulses present a new
opportunity for manipulating the properties of materials. Understanding how
these transient states are different from, or similar to, their thermal
counterparts is key to determining how materials can exhibit properties that
are not found in equilibrium. In this paper, we reexamine the case of the
light-induced insulator-metal phase transition in the prototypical, strongly
correlated material VO, for which a nonthermal Mott-Hubbard transition has
been claimed. Here, we show that heat, even on the ultrafast timescale, plays a
key role in the phase transition. When heating is properly accounted for, we
find a single phase-transition threshold corresponding to the thermodynamic
structural insulator-metal phase transition, and we find no evidence of a
hidden transient Mott-Hubbard nonthermal phase. The interplay between the
initial thermal state and the ultrafast transition may have implications for
other transient states of matter
Inhibition of macrophage migration inhibitory factor decreases proliferation and cytokine expression in bladder cancer cells
BACKGROUND: The importance of various inflammatory cytokines in maintaining tumor cell growth and viability is well established. Increased expression of the proinflammatory cytokine macrophage migration inhibitory factor (MIF) has previously been associated with various types of adenocarcinoma. METHODS: MIF IHC was used to localize MIF in human bladder tissue. ELISA and Western blot analysis determined the synthesis and secretion of MIF by human bladder transitional cell carcinoma cells. The effects of MIF inhibitors (high molecular weight hyaluronate (HA), anti-MIF antibody or MIF anti-sense) on cell growth and cytokine expression were analyzed. RESULTS: Human bladder cancer cells (HT-1376) secrete detectable amounts of MIF protein. Treatment with HA, anti-MIF antibody and MIF anti-sense reduced HT-1376 cell proliferation, MIF protein secretion, MIF gene expression and secreted inflammatory cytokines. Our evidence suggests MIF interacts with the invariant chain, CD74 and the major cell surface receptor for HA, CD44. CONCLUSIONS: This study is the first to report MIF expression in the human bladder and these findings support a role for MIF in tumor cell proliferation. Since MIF participates in the inflammatory response and bladder cancer is associated with chronic inflammatory conditions, these new findings suggest that neutralizing bladder tumor MIF may serve as a novel therapeutic treatment for bladder carcinoma
Neural-network analysis of Parton Distribution Functions from Ioffe-time pseudodistributions
International audienceWe extract two nonsinglet nucleon Parton Distribution Functions from lattice QCD data for reduced Ioffe-time pseudodistributions. We perform such analysis within the NNPDF framework, considering data coming from different lattice ensembles and dis- cussing in detail the treatment of the different source of systematics involved in the fit. We introduce a recipe for taking care of systematics and use it to perform our extraction of light-cone PDFs
Quark mass anomalous dimension and Λ MS ¯ from the twisted mass Dirac operator spectrum
- …