1,654 research outputs found
On the color structure of Yang-Mills theory with static sources in a periodic box
We present an exploratory numerical study on the lattice of the color
structure of the wave functionals of the SU(3) Yang-Mills theory in the
presence of a static pair. In a spatial box with periodic boundary
conditions we discuss the fact that all states contributing to the Feynman
propagation kernel are global color singlets. We confirm this numerically by
computing the correlations of gauge-fixed Polyakov lines with color-twisted
boundary conditions in the time direction. The values of the lowest energies in
the color singlet and octet external source sectors agree within statistical
errors, confirming that both channels contribute to the lowest (global singlet)
state of the Feynman kernel. We then study the case of homogeneous boundary
conditions in the time direction for which the gauge-fixing is not needed. In
this case the lowest energies extracted in the singlet external source sector
agree with those determined with periodic boundary conditions, while in the
octet sector the correlator is compatible with being null within our
statistical errors. Therefore consistently only the singlet external source
contribution has a non-vanishing overlap with the null-field wave functional.Comment: 9 pages, 3 figure
-potential: a numerical study
We report the results of recent lattice simulations aimed at computing the
and potential energies in the singlet and the octet (adjoint)
representation.Comment: 7 pages, 4 figures, poster presented at the 31st International
Symposium on Lattice Field Theory (Lattice 2013), 29 July - 3 August 2013,
Mainz, German
The observation of light nuclei at ALICE and the X(3872) conundrum
The new data reported by ALICE on the production of light nuclei with pT < 10
GeV in Pb-Pb collisions at sqrt(s_NN) = 2.76 TeV are used to compute an
order-of-magnitude estimate of the expected production cross sections of light
nuclei in proton-proton collisions at high transverse momenta. We compare the
hypertriton, helium-3 and deuteron production cross sections to that of
X(3872), measured in prompt pp collisions by CMS. The results we find suggest a
different production mechanism for the X(3872), making questionable any loosely
bound molecule interpretation.Comment: 5 pages, 2 figures. Version accepted on PR
Flavored tetraquark spectroscopy
The recent confirmation of the charged charmonium like resonance Z(4430) by the LHCb experiment strongly suggests the existence of QCD multi quark bound states. Some preliminary results about hypothetical flavored tetraquark mesons are reported. Such states are particularly amenable to Lattice QCD studies as their interpolating operators do not overlap with those of ordinary hidden-charm mesons
Probing the nature of Z_c states via the eta_c rho decay
The nature of the so-called XYZ states is a long-standing problem. It has
been suggested that such particles may be described as compact four-quark
states or loosely bound meson molecules. In the present work we analyze the
Z_c(') -> eta_c rho decay using both approaches. Such channel might provide
useful insights on the nature of the Z_c('), helping discriminating between the
two different models.Comment: 10 pages, 6 figures, 3 tables. Version accepted on Phys.Lett.
Exact Distributed Load Centrality Computation: Algorithms, Convergence, and Applications to Distance Vector Routing
Many optimization techniques for networking protocols take advantage of topological information to improve performance. Often, the topological information at the core of these techniques is a centrality metric such as the Betweenness Centrality (BC) index. BC is, in fact, a centrality metric with many well-known successful applications documented in the literature, from resource allocation to routing. To compute BC, however, each node must run a centralized algorithm and needs to have the global topological knowledge; such requirements limit the feasibility of optimization procedures based on BC. To overcome restrictions of this kind, we present a novel distributed algorithm that requires only local information to compute an alternative similar metric, called Load Centrality (LC). We present the new algorithm together with a proof of its convergence and the analysis of its time complexity. The proposed algorithm is general enough to be integrated with any distance vector (DV) routing protocol. In support of this claim, we provide an implementation on top of Babel, a real-world DV protocol. We use this implementation in an emulation framework to show how LC can be exploited to reduce Babel's convergence time upon node failure, without increasing control overhead. As a key step towards the adoption of centrality-based optimization for routing, we study how the algorithm can be incrementally introduced in a network running a DV routing protocol. We show that even when only a small fraction of nodes participate in the protocol, the algorithm accurately ranks nodes according to their centrality
Flavored tetraquark spectroscopy
The recent confirmation of the charged charmonium like resonance Z(4430) by
the LHCb experiment strongly suggests the existence of QCD multi quarks bound
states. Some preliminary results about hypothetical flavored tetraquark mesons
are reported. Such states are particularly amenable to Lattice QCD studies as
their interpolating operators do not overlap with those of ordinary
hidden-charm mesons.Comment: 7 pages, 7 figures, presented at the 32nd International Symposium on
Lattice Field Theory (Lattice 2014), June 23-28 2014, New York, US
Is transperitoneal laparoscopic adrenalectomy for pheochromocytoma really more challenging? A propensity score-matched analysis
Purpose Minimally invasive surgery is the gold standard treatment for adrenal masses, but it may be a challenging procedure in the case of pheochromocytoma (PHEO). The aim of the present study is to report the results of transperitoneal laparoscopic adrenalectomy (TLA) in cases of PHEO in comparison to other types of adrenal lesions. Methods From 1994 to 2021, 629 patients underwent adrenalectomy. Twenty-two and thirty-five patients, respectively,
were excluded because they underwent bilateral and open adrenalectomy, leaving 572 patients for inclusion. Of these, 114 patients had PHEO (Group A), and 458 had other types of lesions (Group B). To adjust for potential baseline confounders, a propensity score matching (PSM) analysis was conducted. Results After PSM, 114 matched pairs of patients were identified from each group. Statistically significant differences were not observed when comparing the median operative time (85 and 90 min in Groups A and B, respectively, p = 0.627), conversion rate [6 (5.3%) in each group, p = 1.000], transfusion rate [4 (3.5%) and 3 (2.6%) in Groups A and B, respectively, p = 1.000], complication rate [7 (6.1%) and 9 (7.9%) in Groups A and B, respectively, p = 0.796), median postoperative hospital stay (3.9 and 3.6 days in Groups A and B, respectively, p = 0.110), and mortality rate [1 (0.9%) in each group, p = 1.000]. Conclusions Based on this analysis, the results of TLA for PHEO are equivalent to those of TLA for other types of adrenal
lesions, but the fundamental requirements are multidisciplinary patient management and adequate surgeon experience. Further prospective studies are required to draw definitive conclusions
- …