1,006 research outputs found
Monopole Constituents inside SU(n) Calorons
We present a simple result for the action density of the SU(n) charge one
periodic instantons - or calorons - with arbitrary non-trivial Polyakov loop
P_oo at spatial infinity. It is shown explicitly that there are n lumps inside
the caloron, each of which represents a BPS monopole, their masses being
related to the eigenvalues of P_oo. A suitable combination of the ADHM
construction and the Nahm transformation is used to obtain this result.Comment: 8 pages, 1 figure (in three parts), late
Toward TeV Conformality
We study the chiral condensate for an SU(3) gauge theory
with massless Dirac fermions in the fundamental representation when
is increased from 2 to 6. For , our lattice simulations of , where is the Nambu-Goldstone-boson decay constant, agree with
the measured QCD value. For , this ratio shows significant
enhancement, presaging an even larger enhancement anticipated as
increases further, toward the critical value for transition from confinement to
infrared conformality.Comment: 4 pages, 4 figures. v2: revised version for PR
Pattern scaling using ClimGen: monthly-resolution future climate scenarios including changes in the variability of precipitation
Development, testing and example applications of the pattern-scaling approach for generating future climate change projections are reported here, with a focus on a particular software application called “ClimGen”. A number of innovations have been implemented, including using exponential and logistic functions of global-mean temperature to represent changes in local precipitation and cloud cover, and interpolation from climate model grids to a finer grid while taking into account land-sea contrasts in the climate change patterns. Of particular significance is a new approach for incorporating changes in the inter-annual variability of monthly precipitation simulated by climate models. This is achieved by diagnosing simulated changes in the shape of the gamma distribution of monthly precipitation totals, applying the pattern-scaling approach to estimate changes in the shape parameter under a future scenario, and then perturbing sequences of observed precipitation anomalies so that their distribution changes according to the projected change in the shape parameter. The approach cannot represent changes to the structure of climate timeseries (e.g. changed autocorrelation or teleconnection patterns) were they to occur, but is shown here to be more successful at representing changes in low precipitation extremes than previous pattern-scaling methods
Approaching Conformality with Ten Flavors
We present first results for lattice simulations, on a single volume, of the
low-lying spectrum of an SU(3) Yang-Mills gauge theory with ten light fermions
in the fundamental representation. Fits to the fermion mass dependence of
various observables are found to be globally consistent with the hypothesis
that this theory is within or just outside the strongly-coupled edge of the
conformal window, with mass anomalous dimension consistent with 1 over the
range of scales simulated. We stress that we cannot rule out the possibility of
spontaneous chiral-symmetry breaking at scales well below our infrared cutoff.
We discuss important systematic effects, including finite-volume corrections,
and consider directions for future improvement.Comment: 7 pages, 3 figures. Submitted to Physical Review Letters. v2:
corrected global fits. v3: corrected estimation of confidence interval
The Length Distribution of Class I-Restricted T Cell Epitopes Is Determined by Both Peptide Supply and MHC Allele-Specific Binding Preference
HLA class I-binding predictions are widely used to identify candidate peptide targets of human CD8+ T cell responses. Many such approaches focus exclusively on a limited range of peptide lengths, typically 9 aa and sometimes 9-10 aa, despite multiple examples of dominant epitopes of other lengths. In this study, we examined whether epitope predictions can be improved by incorporating the natural length distribution of HLA class I ligands. We found that, although different HLA alleles have diverse length-binding preferences, the length profiles of ligands that are naturally presented by these alleles are much more homogeneous. We hypothesized that this is due to a defined length profile of peptides available for HLA binding in the endoplasmic reticulum. Based on this, we created a model of HLA allele-specific ligand length profiles and demonstrate how this model, in combination with HLA-binding predictions, greatly improves comprehensive identification of CD8+ T cell epitopes.Fil: Trolle, Thomas. Technical University of Denmark; DinamarcaFil: McMurtrey, Curtis. Oklahoma State University; Estados UnidosFil: Sidney, John. La Jolla Institute for Allergy and Immunology; Estados UnidosFil: Bardet, Wilfried. Oklahoma State University; Estados UnidosFil: Osborn, Sean C.. Oklahoma State University; Estados UnidosFil: Kaever, Thomas. La Jolla Institute for Allergy and Immunology; Estados UnidosFil: Sette, Alessandro. La Jolla Institute for Allergy and Immunology; Estados UnidosFil: Hildebrand, Willliam H.. Oklahoma State University; Estados UnidosFil: Nielsen, Morten. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas ; Argentina. Universidad Nacional de San Martín; ArgentinaFil: Peters, Bjoern. La Jolla Institute for Allergy and Immunology; Estados Unido
WW Scattering Parameters via Pseudoscalar Phase Shifts
Using domain-wall lattice simulations, we study pseudoscalar-pseudoscalar
scattering in the maximal isospin channel for an SU(3) gauge theory with two
and six fermion flavors in the fundamental representation. This calculation of
the S-wave scattering length is related to the next-to-leading order
corrections to WW scattering through the low-energy coefficients of the chiral
Lagrangian. While two and six flavor scattering lengths are similar for a fixed
ratio of the pseudoscalar mass to its decay constant, six-flavor scattering
shows a somewhat less repulsive next-to-leading order interaction than its
two-flavor counterpart. Estimates are made for the WW scattering parameters and
the plausibility of detection is discussed.Comment: 8 pages, 6 figure
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