Nucleon transverse momentum-dependent parton distributions in lattice QCD: Renormalization patterns and discretization effects

Lattice QCD calculations of transverse momentum-dependent parton distribution functions (TMDs) in nucleons are presented, based on the evaluation of nucleon matrix elements of quark bilocal operators with a staple-shaped gauge connection. Both time-reversal odd effects, namely, the generalized Sivers and Boer-Mulders transverse momentum shifts, as well as time-reversal even effects, namely, the generalized transversity and one of the generalized worm-gear shifts, are studied. Results are obtained on two different n[subscript f]=2+1 flavor ensembles with approximately matching pion masses but very different discretization schemes: domain-wall fermions (DWF) with lattice spacing a=0.084  fm and pion mass 297 MeV, and Wilson-clover fermions with a=0.114  fm and pion mass 317 MeV. Comparison of the results on the two ensembles yields insight into the length scales at which lattice discretization errors are small, and into the extent to which the renormalization pattern obeyed by the continuum QCD TMD operator continues to apply in the lattice formulation. For the studied TMD observables, the results are found to be consistent between the two ensembles at sufficiently large separation of the quark fields within the operator, whereas deviations are observed in the local limit and in the case of a straight link gauge connection, which is relevant to the studies of parton distribution functions. Furthermore, the lattice estimates of the generalized Sivers shift obtained here are confronted with, and are seen to tend towards, a phenomenological estimate extracted from experimental data.United States. Department of Energy (Grant DE-FG02-96ER40965)United States. Department of Energy (Grant DE-SC-0011090)United States. Department of Energy (Grant DE-FC02-06ER41444

BKB_K using HYP-smeared staggered fermions in Nf=2+1N_f=2+1 unquenched QCD

We present results for kaon mixing parameter $B_K$ calculated using HYP-smeared improved staggered fermions on the MILC asqtad lattices. We use three lattice spacings ($a\approx 0.12$, $0.09$ and $0.06\;$fm), ten different valence quark masses ($m\approx m_s/10-m_s$), and several light sea-quark masses in order to control the continuum and chiral extrapolations. We derive the next-to-leading order staggered chiral perturbation theory (SChPT) results necessary to fit our data, and use these results to do extrapolations based both on SU(2) and SU(3) SChPT. The SU(2) fitting is particularly straightforward because parameters related to taste-breaking and matching errors appear only at next-to-next-to-leading order. We match to the continuum renormalization scheme (NDR) using one-loop perturbation theory. Our final result is from the SU(2) analysis, with the SU(3) result providing a (less accurate) cross check. We find $B_K(\text{NDR}, \mu = 2 \text{GeV}) = 0.529 \pm 0.009 \pm 0.032$ and $\hat{B}_K =B_K(\text{RGI})= 0.724 \pm 0.012 \pm 0.043$, where the first error is statistical and the second systematic. The error is dominated by the truncation error in the matching factor. Our results are consistent with those obtained using valence domain-wall fermions on lattices generated with asqtad or domain-wall sea quarks.Comment: 37 pages, 31 figures, most updated versio

The isimodeni style: traditional beadwork, Zulu trinket or, South African sartorial tradition on Durban’s Golden Mile?

Beadwork is a well-documented aspect of the socio-political culture of isiZulu-speaking groupings in Southern Africa. Whilst scholarship on beadwork deals largely with the denotative and connotative value it offers wearers, this article’s contribution relates both to its commodification and apolitical value by confronting a general assumption that a beadwork style known as isimodeni (modern beadwork), produced as a trinket for tourists along Durban’s racially stratified Golden Mile since the 1960s, is an authentic representation of a Zulu material culture. The paper probes how traditional beadwork and rickshaw rides (with both highly decorated carts and pullers) were earmarked by tourism officials of the time as commodities that could serve a demand for colourful exoticism and accessible “Zulu” culture. Methodologically, the article draws on the visual analysis of beaded artefacts and photographs, in addition to ethnographic data derived from unstructured interviews with beadworkers on the Durban beachfront, to examine how a beadwork tradition transformed into a “Zulu” tourism commodity, and then transmuted into a nationalised form of ethnic identity and sartorial tradition

Surface‐Micromachined Microfiltration Membranes for Efficient Isolation and Functional Immunophenotyping of Subpopulations of Immune Cells

An accurate measurement of the immune status in patients with immune system disorders is critical in evaluating the stage of diseases and tailoring drug treatments. The functional cellular immunity test is a promising method to establish the diagnosis of immune dysfunctions. The conventional functional cellular immunity test involves measurements of the capacity of peripheral blood mononuclear cells to produce pro‐inflammatory cytokines when stimulated ex vivo. However, this “bulk” assay measures the overall reactivity of a population of lymphocytes and monocytes, making it difficult to pinpoint the phenotype or real identity of the reactive immune cells involved. In this research, we develop a large surface micromachined poly‐dimethylsiloxane (PDMS) microfiltration membrane (PMM) with high porosity, which is integrated in a microfluidic microfiltration platform. Using the PMM with functionalized microbeads conjugated with antibodies against specific cell surface proteins, we demonstrated rapid, efficient and high‐throughput on‐chip isolation, enrichment, and stimulation of subpopulations of immune cells from blood specimens. Furthermore, the PMM‐integrated microfiltration platform, coupled with a no‐wash homogeneous chemiluminescence assay (“AlphaLISA”), enables us to demonstrate rapid and sensitive on‐chip immunophenotyping assays for subpopulations of immune cells isolated directly from minute quantities of blood samples. An integrated microfluidic microfiltration platform containing a unique surface micromachined poly‐dimethylsiloxane (PDMS) microfiltration membrane (PMM) and microbeads conjugated with antibodies is reported for rapid, efficient and high‐throughput on‐chip isolation, enrichment, and stimulation of subpopulations of immune cells from blood specimens. Furthermore, the PMM‐integrated microfiltration platform, coupled with a no‐wash homogeneous chemiluminescence assay (“AlphaLISA”), allows rapid and sensitive on‐chip immunophenotyping assays for subpopulations of immune cells isolated directly from minute quantities of blood samples.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/99066/1/adhm_201200378_sm_suppl.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/99066/2/965_ftp.pd