40 research outputs found
On the light glueball spectrum in a holographic description of QCD
AbstractWe investigate the spectra of light scalar and vector glueballs in a holografic description of QCD with a dilaton background bulk field. In particular, we study how the glueball masses depend on the conditions on the dilaton background and on the geometry of the bulk
An Exact Conformal Symmetry Ansatz on Kaluza-Klein Reduced TMG
Using a Kaluza-Klein dimensional reduction, and further imposing a conformal
Killing symmetry on the reduced metric generated by the dilaton, we show an
Ansatz that yields many of the known stationary axisymmetric solutions to TMG.Comment: 20 pages, 1 figure, v3: postprint, added one re
The decays and the Isgur-Wise functions ,
We perform a phenomenological analysis of the decays , where
is a -wave excited meson with total angular momentum or for the light cloud, recently measured by the Belle
Collaboration in the modes (Class I) and (Class III). Making the reasonable assumption of naive
factorization, that we test in decays, Class I decays allow
to extract the Isgur-Wise form factors , at (). We obtain ,
. We discuss the question of the
dependence of these IW functions. We find agreement with the Bakamjian-Thomas
quark model of form factors and, extrapolating at , with Bjorken and
Uraltsev sum rules. We discuss also Class III decays, where the emission diagram contributes. We extract the corresponding
decay constant, that is in agreement with theoretical estimates
at finite mass. Finally, we must warn that corrections could be large
and upset the results of the present stage of this analysis. On the other hand,
we confront present data on the semileptonic rate of mesons to excited
states with theoretical expectations
No more CKY two-forms in the NHEK
We show that in the near-horizon limit of a Kerr-NUT-AdS black hole, the
space of conformal Killing-Yano two-forms does not enhance and remains of
dimension two. The same holds for an analogous polar limit in the case of
extremal NUT charge. We also derive the conformal Killing-Yano -form
equation for any background in arbitrary dimension in the form of parallel
transport.Comment: 36 pages, 12 pdf figures, v2: minor change
Anomalous dimensions and scalar glueball spectroscopy in AdS/QCD
An extended version of the AdS/QCD Soft-Wall model that incorporates QCD-like
anomalous contributions to the dimensions of gauge theory operators is
proposed. This exploratory approach leads to a relation between scalar glueball
masses and beta functions. Using this relation, properties of the glueball mass
spectroscopy that emerge from phenomenological beta functions proposed in the
literature are investigated. The reverse problem is also considered: starting
from a linear Regge trajectory which fits the lattice glueball masses, beta
functions with different asymptotic infrared behaviours are found. Remarkably,
some of them present a fixed point at finite coupling.Comment: 27 pages. V4: Expanded text with more discussions. Results unchanged.
To appear in EPJ
Production of Superoxide Anions by Keratinocytes Initiates P. acnes-Induced Inflammation of the Skin
Acne vulgaris is a chronic inflammatory disorder of the sebaceous follicles. Propionibacterium acnes (P. acnes), a gram-positive anareobic bacterium, plays a critical role in the development of these inflammatory lesions. This study aimed at determining whether reactive oxygen species (ROS) are produced by keratinocytes upon P. acnes infection, dissecting the mechanism of this production, and investigating how this phenomenon integrates in the general inflammatory response induced by P. acnes. In our hands, ROS, and especially superoxide anions (O2•−), were rapidly produced by keratinocytes upon stimulation by P. acnes surface proteins. In P. acnes-stimulated keratinocytes, O2•− was produced by NAD(P)H oxidase through activation of the scavenger receptor CD36. O2•− was dismuted by superoxide dismutase to form hydrogen peroxide which was further detoxified into water by the GSH/GPx system. In addition, P. acnes-induced O2•− abrogated P. acnes growth and was involved in keratinocyte lysis through the combination of O2•− with nitric oxide to form peroxynitrites. Finally, retinoic acid derivates, the most efficient anti-acneic drugs, prevent O2•− production, IL-8 release and keratinocyte apoptosis, suggesting the relevance of this pathway in humans
Memorino on the `1/2 vs. 3/2 Puzzle' in -- a Year Later and a Bit Wiser
The OPE treatment that has been so successful in describing inclusive decays yields sum rules (in particular the Uraltsev sum
rule and its higher moments) implying the dominance of the wave
charm states in over their counterparts. This prediction is
supported by other general arguments as well as quark model calculations, which
illustrate the OPE results, and by preliminary lattice findings. Its failure
would indicate a significant limitation in our theoretical understanding of
. Some experimental issues have been clarified since
a preliminary version of this note had appeared, yet the verdict on the
composition of the final states {\em beyond} , and the two narrow resonances remains unsettled. Establishing which hadronic configurations
-- -- contribute, what their quantum numbers
are and their mass distributions will require considerable experimental effort.
We explain the theoretical issues involved and why a better understanding of
them will be of significant value. Having significant contributions from a mass
continuum distribution below 2.5 GeV raises serious theoretical questions for
which we have no good answer. Two lists are given, one with measurements that
need to be done and one with items of theoretical homework. Some of the latter
can be done by employing existing theoretical tools, whereas others need new
ideas.Comment: 21 pages, no figures; corrected address of one of the authors and
included new measurements by BaBa
Adjuvant Effect of Killed Propionibacterium acnes on Mouse Peritoneal B-1 Lymphocytes and Their Early Phagocyte Differentiation
B-1 lymphocytes are the predominant cells in mouse peritoneal cavity. They express macrophage and lymphocyte markers and are divided into B-1a, B-1b and B-1c subtypes. The role of B-1 cells is not completely clear, but they are responsible for natural IgM production and seem to play a regulatory role. An enriched B-1b cell population can be obtained from non-adherent peritoneal cell cultures, and we have previously demonstrated that these cells undergo differentiation to acquire a mononuclear phagocyte phenotype upon attachment to the substrate in vitro. Nevertheless, the B-1 cell response to antigens or adjuvants has been poorly investigated. Because killed Propionibacterium acnes exhibits immunomodulatory effects on both macrophages and B-2 lymphocytes, we analyzed whether a killed bacterial suspension or its soluble polysaccharide (PS) could modulate the absolute number of peritoneal B-1 cells in BALB/c mice, the activation status of these cells and their ability to differentiate into phagocytes in vitro. In vivo, P. acnes treatment elevated the absolute number of all B-1 subsets, whereas PS only increased B-1c. Moreover, the bacterium increased the number of B-1b cells that were positive for MHC II, TLR2, TLR4, TLR9, IL-4, IL-5 and IL-12, in addition to up-regulating TLR9, CD80 and CD86 expression. PS increased B-1b cell expression of TLR4, TLR9, CD40 and CD86, as well as IL-10 and IL-12 synthesis. Both of the treatments decreased the absolute number of B-1b cells in vitro, suggesting their early differentiation into B-1 cell-derived phagocytes (B-1CDP). We also observed a higher phagocytic activity from the phagocytes that were derived from B-1b cells after P. acnes and PS treatment. The adjuvant effect that P. acnes has on B-1 cells, mainly the B-1b subtype, reinforces the importance of B-1 cells in the innate and adaptive immune responses