Search

Supplementary Figure 1 from Heat Shock Protein 27 Differentiates Tolerogenic Macrophages That May Support Human Breast Cancer Progression

Supplementary Figure 2 from Heat Shock Protein 27 Differentiates Tolerogenic Macrophages That May Support Human Breast Cancer Progression

Supplementary Figure Legends 1-2 from Heat Shock Protein 27 Differentiates Tolerogenic Macrophages That May Support Human Breast Cancer Progression

Approaches to a non-perturbative formulation of chiral gauge theories on the lattice regulator through a gauge non-invariant approach is discussed. Non-perturbative gauge fixing of Abelian and non-Abelian gauge theories are also discussed in this context.

After a brief introduction to some of the salient features, I present recent results of our group at SINP on two long-standing problems: (i) chiral and topological properties of lattice QCD with Wilson fermions, and (ii) non-perturbative gauge-fixing to address chiral gauge theories on lattice.

We calculate pion mass, pion decay constant, PCAC quark mass and nucleon mass in two flavour lattice QCD with unimproved Wilson fermion and gauge actions. Simulations are performed using DD-HMC algorithm at two lattice spacings and two volumes for several values of the quark mass. The cutoff effects in pion mass and nucleon mass for the explored region of parameter space are found to be negligible. The chiral behaviours of pion mass, pion decay constant and quark condensate are found to be qualitatively consistent with NLO chiral perturbation theory., 18 pages and 15 figures

Time-course microarray experiments are capable of capturing dynamic gene expression profiles. It is important to study how these dynamic profiles depend on the multiple factors that characterize the experimental condition under which the time course is observed. Analytic methods are needed to simultaneously handle the time course and factorial structure in the data. We developed a method to evaluate factor effects by pooling information across the time course while accounting for multiple testing and nonnormality of the microarray data. The method effectively extracts gene-specific response features and models their dependency on the experimental factors. Both longitudinal and cross-sectional time-course data can be handled by our approach. The method was used to analyze the impact of age on the temporal gene response to burn injury in a large-scale clinical study. Our analysis reveals that 21% of the genes responsive to burn are age-specific, among which expressions of mitochondria and immunoglobulin genes are differentially perturbed in pediatric and adult patients by burn injury. These new findings in the body’s response to burn injury between children and adults support further investigations of therapeutic options targeting specific age groups. The methodology proposed here has been implemented in R package “TANOVA” and submitted to the Comprehensive R Archive Network at http://www.r-project.org/ . It is also available for download at http://gluegrant1.stanford.edu/TANOVA/ .

We investigate the continuum limit of a compact formulation of the lattice U(1) gauge theory in 4 dimensions using a nonperturbative gauge-fixed regularization. We find clear evidence of a continuous phase transition in the pure gauge theory for all values of the gauge coupling (with gauge symmetry restored). When probed with quenched staggered fermions with U(1) charge, the theory clearly has a chiral transition for large gauge couplings. We identify the only possible region in the parameter space where a continuum limit with nonperturbative physics may appear., Comment: latex, 9 pages, 7 figures. Version accepted for publication in Phys. Lett. B

We briefly describe motivations for studying transverse lattice QCD. Presence of constraint equation for fermion field on the light front allows different methods to put fermions on a transverse lattice. We summarize our numerical investigation of two approaches using (a) forward and backward derivatives and (b) symmetric derivatives.

We study low lying hadronic spectrum with two degenerate flavours of naive Wilson fermions and unimproved Wilson gauge action using DDHMC algorithm as a function of PCAC quark mass at two different lattice spacings and different volumes. The scaling violations of the pionic observables and the nucleon mass are found to be negligible. The chiral behaviour of different observables are compared with NLO chiral perturbation theory predictions. Using the chiral Ward identity we calculate chiral condensate and it is found to be compatible with NLO chiral perturbation theory prediction.

We study the two-point Topological Charge Density Correlator (TCDC) in lattice QCD with two degenerate flavours of naive Wilson fermions and unimproved Wilson gauge action at two values of lattice spacings and different volumes, for a range of quark masses. Configurations are generated with DDHMC algorithm and smoothed with HYP smearing. In order to shed light on the mechanisms leading to the observed suppression of topological susceptibility with respect to the decreasing quark mass and decreasing volume, in this work, we carry out a detailed study of the two-point TCDC. We have shown that, (1) the TCDC is negative beyond a positive core and radius of the core shrinks as lattice spacing decreases, (2) as the volume decreases, the magnitude of the contact term and the radius of the positive core decrease and the magnitude of the negative peak increases resulting in the suppression of the topological susceptibility as the volume decreases, (3) the contact term and radius of the positive core decrease with decreasing quark mass at a given lattice spacing and the negative peak increases with decreasing quark mass resulting in the suppression of the topological susceptibility with decreasing quark mass, (4) increasing levels of smearing suppresses the contact term and the negative peak keeping the susceptibility intact and (5) both the contact term and the negative peak diverge in nonintegrable fashion as lattice spacing decreases., 7 pages, 5 figures, talk presented at-The 30th International Symposium on Lattice Field Theory-Lattice 2012, June 24-29, 2012 Cairns, Australia

We study the two-point Topological Charge Density Correlator (TCDC) in lattice QCD with two degenerate flavours of unimproved Wilson fermions and Wilson gauge action at two values of lattice spacings and different volumes, for a range of quark masses. Configurations are generated with DDHMC algorithm and smoothed with HYP smearing. In order to shed light on the mechanisms leading to the observed suppression of topological susceptibility with respect to the decreasing quark mass and decreasing volume, in this work, we carry out a detailed study of the two-point TCDC. We have shown that, (1) the TCDC is negative beyond a positive core and radius of the core shrinks as lattice spacing decreases, (2) as the volume decreases, the magnitude of the contact term and the radius of the positive core decrease and the magnitude of the negative peak increases resulting in the suppression of the topological susceptibility as the volume decreases, (3) the contact term and radius of the positive core decrease with decreasing quark mass at a given lattice spacing and the negative peak increases with decreasing quark mass resulting in the suppression of the topological susceptibility with decreasing quark mass, (4) increasing levels of smearing suppresses the contact term and the negative peak keeping the susceptibility intact and (5) both the contact term and the negative peak diverge in nonintegrable fashion as lattice spacing decreases. It is gratifying to note that observations similar to 1 and 5 have been made using topological charge density operator based on chiral fermion. The observations 2 and 3 may be confirmed more precisely by using formulations based on chiral fermions., Comment: some qualifying remarks are added, results unchanged

We numerically investigate the phase diagram of pure U (1) gauge theory with gauge fixing at strong gauge coupling. The FM-FMD phase transition, which proved useful in defining Abelian lattice chiral gauge theory, persists also at strong gauge coupling. However, there the transition seems no longer to be continuous. At large gauge couplings we find evidences for confinement.

We demonstrate the effectiveness of averaging over the Wilson parameter r (which has been proposed earlier) in removing the cutoff effects of naive Wilson fermions in both the anomaly term and the pseudoscalar density term in the flavor singlet axial Ward identity at O(g^2) involving slowly varying background gauge fields. We show that it is the physical fermion contribution which is largely influenced by the r averaging. We have studied the possible interplay between finite size and cutoff effects by investigating in detail naive, O(a) improved and OStm Wilson fermion cases for a range of volumes and lattice fermion mass (am). For naive Wilson fermions r averaging is shown to remove the effects of the interplay. We have shown that for the pseudoscalar density term to O (g^2) the lattice result differs from the continuum result by exhibiting considerable am dependence which appears to be a manifestation of cutoff effects with naive Wilson fermion. The pseudoscalar density term to O(g^2) is shown to be almost independent of am when r-averaging is performed., 14 pages, 13 figures, revised

We address a long standing problem regarding topology in lattice simulations of QCD with unimproved Wilson fermions. Earlier attempt with unimproved Wilson fermions at \beta =5.6 to verify the suppression of topological susceptibility with decreasing quark mass (m_q) was unable to unambiguously confirm the suppression. We carry out systematic calculations for two degenerate flavours at two different lattice spacings (\beta = 5.6 and 5.8). The effects of quark mass, lattice volume and the lattice spacing on the spanning of different topological sectors are presented. We unambiguously demonstrate the suppression of the topological susceptibility with decreasing quark mass, expected from chiral Ward identity and chiral perturbation theory., Comment: 1 figure and clarifying remarks added, results and conclusion unchanged. Accepted for publication in Physics Letters B

Results of numerical investigation of the Wilson-Yukawa approach to a lattice regularized chiral gauge theory are presented. SU(2) and U(1) models are considered in the global symmetry limit. Conclusions are drawn from the obtained phase diagram and the lowest lying spectrum of the models and by comparing numerical data with available analytic results. For small Wilson-Yukawa coupling, the globally symmetric models turn out to describe fermions and scalars interacting weakly through an Yukawa interaction and the fermion doublers remain in the physical spectrum, while for relatively strong Wilson-Yukawa coupling the doublers do decouple, but the residual scalar-fermion theory seems to produce, at least in the symmetric phase, only free neutral fermions. From these considerations it is argued that prospect of a lattice regularized chiral gauge theory in this approach is quite unfavorable.

The fermion mass spectrum is studied in the strong-coupling symmetric (PMS) phase of a scalar-fermion model derived from a lattice proposal of the standard model with Wilson-Yukuwa coupling. We find that the fermions are massive and argue for the following interpretation of our numerical results in this PMS phase. The lowest lying fermion spectrum in this phase consists only of a Dirac fermion which is a singlet with respect to the SU(2)L group (the “neutral” fermion). We give evidence that the SU(2)L doublet fermion (the “charged” fermion), in terms of which the model is originally formulated and which is present in the weak-coupling symmetric phase, is absent in the PMS phase. The neutral fermion is only weakly coupled to the scalar particles and appears to become non-interacting in the scaling region. If this interpretation is correct, the Wilson-Yukawa approach does not lead to a satisfactory lattice formulation of the standard model.

We study the scaling laws for the fermion mass and the scalar field expectation value in the weak coupling region of the broken phase of a lattice regularized chiral-invariant SU(2)L ⊗ SU(2)R fermion-Higgs model with bare Yukawa coupling y and Wilson-Yukawa coupling w. In particular we concentrate on the region in the vicinity of the line A, which is the line of maximal values of y + 4w on the critical surface containing the gaussian fixed point. We have not found any indication for the existence of a nontrivial fixed point on that line or anywhere else in the weak coupling region. The renormalized Yukawa coupling yR as a function of the fermionic correlation length appears to be bounded from above. The upper bound obtained from the numerical data at w = 0 is compatible with the perturbative unitarity bound. Furthermore, in the weak coupling region, including the line A, it is not possible to choose w such that the unwanted fermion doublers would be removed from the physical particle pectrum.

We present an analysis of the eigenvalue spectra of the Dirac operator M and related operators M′ and M†M in an SU(2) ⊗ SU(2) and a Z(2) ⊗ Z(2) fermion-Higgs model in the quenched approximation. We especially study the spectra in the symmetric and broken symmetry phases along the crossover line which was recently discovered in these models in numerical simulations. It turns out that in the symmetric phases of both models zero modes emerge along the crossover line. In the case of the Z(2) model the zero modes follow the crossover line into the broken symmetry phase whereas in the case of the SU(2) model they appear to stop at the phase transition line between the symmetric and the broken phases.

Dependence of $a/r_c$ (inverse Sommer parameter in units of lattice spacing $a$) on $am_q$ (quark mass in lattice unit) has been observed in all lattice QCD simulations with sea quarks including the ones with improved actions. How much of this dependence is a scaling violation has remained an intriguing question. Our approach has been to investigate the issue with an action with known lattice artifacts, i.e., the standard Wilson quark and gauge action with $\beta=5.6$ and 2 degenerate flavors of sea quarks on $ 16^3 \times 32 $ lattices. In order to study in detail the sea quark mass dependence, measurements are carried out at eight values of the Wilson hopping parameter $\kappa$ in the range 0.156 - 0.158 corresponding to PCAC quark mass values $am_q$ from about 0.07 to below 0.015. We analyze the static potential by fitting to the familiar phenomenological form and extract $a/r_c$. Though scaling violations may indeed be present for relatively large $am_q$, a consistent scenario at sufficiently small $am_q$ seems to emerge in the mass-independent scheme where for a fixed $\beta$, $1/r_0$ and $\sqrt{\sigma}$ have linear dependence on $m_q$ as physical effects similar to the quark mass dependence of the rho mass. We present evidence for this scenario and accordingly extract the lattice scale $a$ by chiral extrapolation to the physical point. Care has been exercised to determine optimal values of all fitting parameters and accuracy of the chiral extrapolation. An independent determination of the scale $a$ by chiral extrapolation of the rho mass is consistent with the scale obtained above ($a$ = 0.08041(12)(77) fm, $a^{-1}$ = 2.454(4)(23) GeV)., Comment: 26 pages, 17 figures

The flavour singlet axial Ward identity with Osterwalder-Seiler twisted mass Wilson fermion action is studied on a finite lattice, with finite fermion mass and the Wilson parameter r up to 1. Approach to the infinite volume chiral limit and emergence of the anomaly is significantly better than that obtained with O(a) and O(a^2) improved fermion actions. We have shown explicitly that up to O(g^2), parity violating terms cancel in the Ward identity even at finite volume and finite lattice spacing., Comment: Typos corrected

Fermion spectrum is studied in the strong coupling symmetric (PMS) phase of the Smit-Swift model in the global symmetry limit using quenched approximation. Two Dirac fermions, a singlet and a doublet with respect to SU(2) L , are found in the low-lying spectrum with masses m ′ F and m ″ F respectively, satisfying m ′ F m ″ F . Their doublers decouple quite easily at the chosen value of the Wilson-Yukawa coupling ω = 0.5. We also investigate whether the masses of the two “physical” fermions scale to zero as κ κ c at the same critical value of the Yukawa coupling y and therefore appear simultaneously in the continuum limit. The present numerical evidence for that is inconclusive, but the difference m ′ F − m ″ F is much smaller than expected from some analytic considerations.

We present the phase structure of the chiral SU(2) L ⊗ SU(2) R scalar-fermion model on the lattice with on-site Yukawa coupling y and Wilson-Yukawa coupling w for positive y and w . The hopping parameter κ of the four-component scalar field of fixed length is both positive and negative. From the different behaviour of several observables ferromagnetic, paramagnetic and antiferromagnetic phases can be distinguished. They split into different regions or phases with small and large y + 4 w . A similar structure is also found in the quenched approximation. In addition, in the unquenched case a ferrimagnetic phase is found at negative κ around y + 4 w ≈ √2. We discuss fermion masses in various regions and point out the possibilities of decoupling the unwanted fermion doublers in the continuum limit in analogy to the Wilson mechanism.

The fermion-scalar sector of the lattice version of the standard model proposed by Smit and Swift is studied in the quenched approximation. As the scaling region is approached in the broken phase, we find that the doublers of the chirally coupled fermions can be decoupled by giving them masses of the order of the cut-off without affecting the physical spectrum.

Using dynamical fermions we study the decoupling of the fermion doublers of chiral lattice fermions in the broken symmetry phase of a scalar-fermion model. The model uses a chiral invariant Wilson term, called a Wilson-Yukawa term with coupling strength w , in addition to the usual Yukawa coupling y . We find qualitative agreement with our results obtained before in the quenched approximation. First in the w = 0 case we establish a strong Yukawa coupling region. Then for relatively large but fixed w we confirm that the fermion doublers can be easily decoupled by giving them masses of the order of the cutoff as the symmetry restoring transition is approached.

Lattice QCD with Wilson fermions has entered a very active phase thanks to recent theoretical, algorithmic and technological advances. In order to identify the significant factors underlying the recent successes and to provide benchmark results, we have initiated a program to achieve accurate simulation results for unimproved Wilson action (both gauge and fermion sectors). In this work we present our preliminary results for pion mass and decay constant and quark mass measured using local interpolating operators.

In this work we perform a detailed numerical analysis of ($1+1$) dimensional lattice ${\ensuremath{\phi}}^{4}$ theory. We explore the phase diagram of the theory with two different parametrizations. We find that symmetry breaking occurs only with a negative mass-squared term in the Hamiltonian. The renormalized mass ${m}_{R}$ and the field renormalization constant $Z$ are calculated from both coordinate space and momentum space propagators in the broken symmetry phase. The critical coupling for the phase transition and the critical exponents associated with ${m}_{R}$, $Z$ and the order parameter are extracted using a finite-size scaling analysis of the data for several volumes. The scaling behavior of $Z$ has the interesting consequence that $⟨{\ensuremath{\phi}}_{R}⟩$ does not scale in $1+1$ dimensions. We also calculate the renormalized coupling constant ${\ensuremath{\lambda}}_{R}$ in the broken symmetry phase. The ratio ${\ensuremath{\lambda}}_{R}/{m}_{R}^{2}$ does not scale and appears to reach a value independent of the bare parameters in the critical region in the infinite volume limit.

We investigate the topological charge in 1+1 dimensional {phi}{sup 4} theory on a lattice with antiperiodic boundary condition (APBC) in the spatial direction. We propose a simple order parameter for the lattice theory with APBC and we demonstrate its effectiveness. Our study suggests that kink condensation is a possible mechanism for the order-disorder phase transition in the 1+1 dimensional {phi}{sup 4} theory. With renormalizations performed on the lattice with periodic boundary condition (PBC), the topological charge in the renormalized theory is given as the ratio of the order parameters in the lattices with APBC and PBC. We present a comparison of topological charges in the bare and the renormalized theory and demonstrate invariance of the charge of the renormalized theory in the broken symmetry phase.

We address the problems of fermions in light front QCD on a transverse lattice. We propose and numerically investigate different approaches of formulating fermions on the light front transverse lattice. In one approach we use forward and backward derivatives. There is no fermion doubling and the helicity flip term proportional to the fermion mass in the full light front QCD becomes an irrelevant term in the free field limit. In the second approach with symmetric derivative (which has been employed previously in the literature), doublers appear and their occurrence is due to the decoupling of even and odd lattice sites. We study their removal from the spectrum in two ways namely, light front staggered formulation and the Wilson fermion formulation. The numerical calculations in free field limit are carried out with both fixed and periodic boundary conditions on the transverse lattice and finite volume effects are studied. We find that an even-odd helicity flip symmetry on the light front transverse lattice is relevant for fermion doubling., 7 figures, revtex4

Gauge fixed domain wall fermions are investigated in the reduced model at small Yukawa couplings. We present chiral propagators at the waveguide boundaries using quenched numerical simulations and analytic methods. There is no evidence of mirror chiral modes at the waveguide boundaries., Comment: 7 pages LaTex, 3 postscript version

Renormalized Yukawa couplings are measured for a wide range of bare parameters and are found to be in good agreement with 1-loop perturbation theory. With the inclusion of a weak Wilson-Yukawa coupling, the fermion doublers can at most be given masses of the order of the electroweak scale.

We investigate a U(1) lattice chiral gauge theory with domain wall fermions and gauge fixing. In the reduced model limit, our perturbative and numerical investigations at Yukawa coupling y=1 show that there are no extra mirror chiral modes. The longitudinal gauge degrees of freedom have no effect on the free domain wall fermion spectrum consisting of opposite chiral modes at the domain wall and the anti-domain wall which have an exponentially damped overlap. Our numerical investigation at small Yukawa couplings also leads to similar conclusions as above., Lattice 2000 (Chiral Gauge Theories), 8 pages, 7 ps figures, minor changes

We investigate a U(1) lattice chiral gauge theory with domain wall fermions and compact gauge fixing. In the reduced model limit, our perturbative and numerical investigations show that there exist no extra mirror chiral modes. The longitudinal gauge degrees of freedom have no effect on the free domain wall fermion spectrum consisting of opposite chiral modes at the domain wall and at the anti-domain wall which have an exponentially damped overlap., 16 pages revtex, 5 postscript figures, PRD version

By an explicit calculation of the continuum limit of the triangle graph amplitude in lattice QED we show that in the axial Ward identity the ABJ anomaly exactly cancels the pseudoscalar density term in the limit of infinite fermion mass $m$. The result, a reflection of decoupling of the heavy fermion, provides a convenient framework for computing the flavor-singlet or U(1) axial anomaly in non-Abelian gauge theories on lattice. Our calculations on the lattice are performed using Wilson fermions but the results are general., 8 pages

We investigate a U(1) lattice chiral gauge theory with the waveguide formulation of the domain wall fermions and with compact gauge fixing. In the reduced model limit, there seems to be no mirror chiral modes at the waveguide boundary., Comment: LATTICE99 (chiral gauge theories), 3 pages, 3 figures

We propose a formulation of lattice fermions with one-sided differences that is hermitian, chirally symmetric (barring a bare mass term) and completely free of doubling. To obtain the axial anomaly in perturbation theory it was necessary to break chiral symmetry on the lattice only through a bare mass term for the physical fermion. The chiral limit may be taken once the continuum limit is reached. We comment on the role of the mass term with examples elsewhere in field theory., 3 pages, LateX, uses espcrc2.sty (attached), Talk presented at LATTICE96(chiral gauge)

We investigate on the lattice the Yukawa models in 2 dimensions with Z(2) and U(1) symmetries. These models reduce to the usual and chiral Gross-Neveu models, respectively, when the kinetic and the selfcoupling terms of the scalar field are turned off. The numerical data and mean field arguments suggest that, at least for some range of the scalar field hopping parameter, fermion mass is dynamically generated for arbitrarily weak Yukawa coupling. The models are asymptotically free in this coupling, like the Gross-Neveu models, even when the scalar quartic selfcoupling is strong., Comment: LaTeX, 11 pages (including 4 postscript figures); OUTP-93-01P (HLRZ 93-15)

We present numerical evidence that the 2d Yukawa models with strong quartic selfcoupling of the scalar field have the same phase structure and are asymptotically free in the Yukawa coupling like the Gross-Neveu models., talk at Lattice '92, Amsterdam, 4 pages, 4 figures (included as PS files), requires espcrc2.sty, Juelich preprint HLRZ 92-97

The fermion mass spectrum is studied in the quenched approximation in the strong coupling vortex phase (VXS) of a globally U(1)$_L \otimes$U(1)$_R$ symmetric scalar-fermion model in two dimensions. In this phase fermion doublers can be completely removed from the physical spectrum by means of a strong Wilson-Yukawa coupling. The lowest lying fermion spectrum in this phase consists most probably only of a massive Dirac fermion which has charge zero with respect to the $U(1)_L$ group. We give evidence that the fermion which is charged with respect to that subgroup is absent in the VXS phase. When the $U(1)_L$ gauge fields are turned on, the neutral fermion may couple chirally to the massive vector boson state in the confinement phase. The outcome is very similar to our findings in the strong coupling symmetric phase (PMS) of fermion-Higgs models with Wilson-Yukawa coupling in four dimensions, with the exception that in four dimensions the neutral fermion does most probably decouple from the bosonic bound states., 21 pages, 6 postscript figures (appended), Amsterdam ITFA 92-21, HLRZ J\"ulich 92-52

We study by numerical simulation a lattice Yukawa model with naive fermions at intermediate values of the Yukawa coupling $y$ when the nearest neighbour coupling $\kp$ of the scalar field $\Phi$ is very weakly ferromagnetic ($\kp \approx 0$) or even antiferromagnetic ($\kappa < 0$) and the nonvanishing value of $\vev$ is generated by the Yukawa interaction. The renormalized Yukawa coupling $y_R$ achieves here its maximal value and this $y$-region is thus of particular importance for lattice investigations of strong Yukawa interaction. However, here the scalar field propagators have a very complex structure caused by fermion loop corrections and by the proximity of phases with antiferromagnetic properties. We develop methods for analyzing these propagators and for extracting the physical observables. We find that going into the negative $\kp$ region, the scalar field renormalization constant becomes small and $y_R$ does not seem to exceed the unitarity bound, making the existence of a nontrivial fixed point in the investigated Yukawa model quite unlikely., Comment: 22 pages plus 13 figures

Quenched studies of a global U(1) symmetric Wilson-Yukawa model in two dimensions show no evidence of a charged fermion in the vortex phase at strong Wilson-Yukawa coupling while there is strong indication of a massive neutral fermion. However, with the U(1)$_L$ gauge field turned on, we use dimensional arguments to suggest that the neutral fermion appears to couple chirally to a massive vector boson state., Comment: 4 pages, 2 postscript figures (appended), Wash. U

Quenched fermion calculations are carried out on the βg = 2.3 line of the lattice SU(2) gauge-Higgs system. Chiral symmetry is always broken on the confinement side of the Higgs transition. For l = 12 fermions the symmetry is restored the moment one enters the Higgs region. However, for l = 1 fermions it is possible to have both chirally broken and chirally symmetric Higgs regions. These conclusions follow from evaluations of a3〈ΨΨ〉l and from spectrum calculations in the pseudoscalar meson and the fermion-scalar bound-state channels.