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Sep 19, 2013
09/13

by
D. K. Sinclair

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Lattice QCD allows us to simulate QCD at non-zero temperature and/or densities. Such equilibrium thermodynamics calculations are relevant to the physics of relativistic heavy-ion collisions. I give a brief review of the field with emphasis on our work.

Source: http://arxiv.org/abs/hep-lat/0701010v2

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Sep 18, 2013
09/13

by
D. K. Sinclair

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I review the progress that has been made in light hadron spectroscopy from lattice QCD, since the LATTICE'94 conference in Bielefeld.

Source: http://arxiv.org/abs/hep-lat/9509058v2

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Sep 22, 2013
09/13

by
D. K. Sinclair

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Suggested holographic duals of QCD, based on AdS/CFT duality, predict that one should be able to vary the scales of colour confinement and chiral-symmetry breaking independently. Furthermore they suggest that such independent variation of scales can be achieved by the inclusion of extra 4-fermion interactions in QCD. We simulate lattice QCD with such extra 4-fermion terms at finite temperatures and show that for strong enough 4-fermion couplings the deconfinement transition occurs at a lower...

Source: http://arxiv.org/abs/0805.4627v2

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Sep 18, 2013
09/13

by
D. K. Sinclair

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We use lattice QCD simulations to test some of the predictions of proposed AdS/QCD (holographic) duals for QCD. In particular, these duals predict that the scale of chiral symmetry breaking ($\chi$SB) can be varied independently from that of confinement, with the proviso that the scale of $\chi$SB cannot be longer than that of confinement. We simulate lattice QCD with 2 quarks in the fundamental representation of colour and with additional 4-fermion interactions (suggested by AdS/QCD), at...

Source: http://arxiv.org/abs/0809.0879v1

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Sep 21, 2013
09/13

by
Seyong Kim; D. K. Sinclair

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We present the first direct evidence that quenched QCD differs from full QCD in the chiral ($m_q \rightarrow 0$) limit, as predicted by chiral perturbation theory, from our quenched lattice QCD simulations at $\beta = 6/g^2 = 6.0$. We measured the spectrum of light hadrons on $16^3 \times 64$, $24^3 \times 64$ and $32^3 \times 64$, using staggered quarks of masses $m_q=0.01$, $m_q=0.005$ and $m_q=0.0025$. The pion masses showed clear evidence for logarithmic violations of the PCAC relation...

Source: http://arxiv.org/abs/hep-lat/9502004v1

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Sep 21, 2013
09/13

by
D. K. Sinclair; J. B. Kogut

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We study QCD with 2 and 3 flavours of colour-sextet quarks. The 2-flavour theory is a candidate Walking Technicolor theory. Since we are attempting to distinguish whether this theory is walking or conformal, we also study the 3-flavour theory, which is believed to be conformal, for comparison. We simulate lattice QCD with 2 and 3 flavours of colour-sextet staggered quarks at finite temperatures to determine the scales of confinement and chiral-symmetry breaking from the positions of the...

Source: http://arxiv.org/abs/1008.2468v1

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Sep 21, 2013
09/13

by
J. B. Kogut; D. K. Sinclair

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We simulate 3-flavour lattice QCD with a small chemical potential $\mu_I$ for isospin, at temperatures close to the finite temperature transition. Using quark masses just above the critical mass for zero chemical potential, we determine the position of the transition from hadronic matter to a quark-gluon plasma as a function of $\mu_I$. We see evidence for a critical endpoint where the transition changes from a crossover to a first-order transition as $\mu_I$ is increased. We argue that QCD at...

Source: http://arxiv.org/abs/hep-lat/0407041v1

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Sep 21, 2013
09/13

by
J. B. Kogut; D. K. Sinclair

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QCD at a finite quark-number chemical potential $\mu$ has a complex fermion determinant, which precludes its study by standard lattice QCD simulations. We therefore simulate lattice QCD at finite $\mu$ in the phase-quenched approximation, replacing the fermion determinant with its magnitude. These simulations are used to study the finite temperature transition for small $\mu$,where the position and nature of this transition are expected to be unchanged by this approximation. We look for the...

Source: http://arxiv.org/abs/0712.2625v2

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Sep 21, 2013
09/13

by
D. K. Sinclair; J. B. Kogut

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We simulate 3-flavour lattice QCD at finite quark-number chemical potential mu in the phase-quenched approximation, close to the finite temperature transition. Working close to the critical quark mass, we find no evidence for the expected critical endpoint at small mu. We are performing further simulations aimed at calculating the equation-of-state of this theory outside of the superfluid domain, where its phase structure is expected to mimic the full theory.

Source: http://arxiv.org/abs/0709.2367v1

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Sep 22, 2013
09/13

by
J. B. Kogut; D. K. Sinclair

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Born-Infeld non-linear electrodynamics arises naturally as a field theory description of the dynamics of strings and branes. Most analyses of this theory have been limited to studying it as a classical field theory. We quantize this theory on a Euclidean 4-dimensional space-time lattice and determine its properties using Monte-Carlo simulations. The electromagnetic field around a static point charge is measured using Luscher-Weisz methods to overcome the sign problem associated with the...

Source: http://arxiv.org/abs/hep-lat/0603017v2

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Sep 17, 2013
09/13

by
D. K. Sinclair; J. B. Kogut

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QCD with 2 flavours of massless colour-sextet quarks is studied as a theory which might exhibit a range of scales over which the running coupling constant evolves very slowly (walks). We simulate lattice QCD with 2 flavours of sextet staggered quarks to determine whether walks, or if it has an infrared fixed point, making it a conformal field theory. Our initial simulations are performed at finite temperatures $T=1/N_ta$ ($N_t=4$ and $N_t=6$), which allows us to identify the scales of...

Source: http://arxiv.org/abs/1003.0439v1

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2.0

Jun 29, 2018
06/18

by
D. K. Sinclair; J. B. Kogut

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QCD at finite quark-/baryon-number density, which describes nuclear matter, has a sign problem which prevents direct application of standard simulation methods based on importance sampling. When such finite density is implemented by the introduction of a quark-number chemical potential $\mu$, this manifests itself as a complex fermion determinant. We apply simulations using the Complex Langevin Equation (CLE) which can be applied in such cases. However, this is not guaranteed to give correct...

Topic: High Energy Physics - Lattice

Source: http://arxiv.org/abs/1611.02312

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Sep 20, 2013
09/13

by
J. B. Kogut; D. K. Sinclair

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QCD with two flavours of massless colour-sextet quarks is considered as a model for conformal/walking Technicolor. If this theory possess an infrared fixed point, as indicated by 2-loop perturbation theory, it is a conformal(unparticle) field theory. If, on the other hand, a chiral condensate forms on the weak-coupling side of this would-be fixed point, the theory remains confining. The only difference between such a theory and regular QCD is that there is a range of momentum scales over which...

Source: http://arxiv.org/abs/1002.2988v3

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Sep 23, 2013
09/13

by
J. B. Kogut; D. K. Sinclair

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We have been studying QCD with 2 flavours of colour-sextet quarks to distinguish whether it is QCD-like or conformal. For comparison we are now studying QCD with 3 flavours of colour-sextet quarks, which is believed to be conformal in the chiral limit. Here we present the results of simulations of lattice QCD with 3 colour-sextet quarks at finite temperatures on lattices of temporal extent $N_t=4$ and 6, with masses small enough to yield access to the chiral limit. As for the 2-flavour case, we...

Source: http://arxiv.org/abs/1111.3353v1

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Sep 18, 2013
09/13

by
D. K. Sinclair; J. B. Kogut

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Born-Infeld non-linear electrodynamics was introduced to render the self energy of a point particle finite. It has recently been revived as a field theory for branes and strings. We quantize this theory on a Euclidean space-time lattice, using Metropolis Monte-Carlo simulations to measure the properties of the quantum field theory. Luscher-Weisz methods are used to measure the electromagnetic fields from a static point charge. The D field from a point charge appears to be identical to that for...

Source: http://arxiv.org/abs/hep-lat/0509097v1

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2.0

Jun 30, 2018
06/18

by
D. K. Sinclair; J. B. Kogut

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We study QCD with 2 colour-sextet quarks as a walking-Technicolor candidate. As such it provides a description of the Higgs sector of the standard model, in which the Higgs field is replaced by the Goldstone `pions' of this QCD-like theory, and the Higgs itself is the $\sigma$. Such a theory will need to be extended if it is to also give masses to the quarks and leptons. What we are attempting to determine is whether it is indeed QCD-like and hence walking, or if it has an infrared fixed point...

Topic: High Energy Physics - Lattice

Source: http://arxiv.org/abs/1410.8494

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Sep 18, 2013
09/13

by
J. B. Kogut; D. K. Sinclair

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We simulate lattice QCD with dynamical $u$ and $d$ quarks at finite chemical potential, $\mu_I$, for the third component of isospin ($I_3$), at both zero and at finite temperature. At zero temperature there is some $\mu_I$, $\mu_c$ say, above which $I_3$ and parity are spontaneously broken by a charged pion condensate. This is in qualitative agreement with the prediction of effective (chiral) Lagrangians which also predict $\mu_c=m_\pi$. This transition appears to be second order, with scaling...

Source: http://arxiv.org/abs/hep-lat/0202028v2

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Sep 21, 2013
09/13

by
J. B. Kogut; D. K. Sinclair

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We have simulated lattice QCD with 2 flavours of massless staggered quarks. An irrelevant chiral 4-fermion interaction was added to the standard quark action to allow us to simulate at zero quark mass. Thermodynamics was studied on lattices of temporal extent 6. Clear evidence for a second order chiral transition was observed and the critical exponents $\beta_{mag}$, $\delta$, $\nu$ and $\gamma_{mag}$ were measured. These exponents did not agree with those expected by standard universality...

Source: http://arxiv.org/abs/hep-lat/0104011v2

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Sep 22, 2013
09/13

by
J. B. Kogut; D. K. Sinclair

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We study quenched QCD at finite chemical potential, $\mu_I$, for the third component of isospin and quenched two-colour QCD at finite chemical potential, $\mu$, for quark number. In contrast to the quenched approximation to QCD at finite quark-number chemical potential, the quenched approximations to these theories behave similarly to the full theories. The reason is that these theories have real positive fermion determinants. In both of these theories there is some critical chemical potential...

Source: http://arxiv.org/abs/hep-lat/0201017v2

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Sep 22, 2013
09/13

by
J. B. Kogut; D. K. Sinclair

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We simulate two-flavour lattice QCD with at a finite chemical potential $\mu_I$ for isospin, and finite temperature. At small $\mu_I$, we determine the position of the crossover from hadronic matter to a quark-gluon plasma as a function of $\mu_I$. At larger $\mu_I$ we observe the phase transition from the superfluid pion-condensed phase to a quark-gluon plasma, noting its change from second order to first order as $\mu_I$ is increased. We also simulate two-flavour lattice QCD at zero quark...

Source: http://arxiv.org/abs/hep-lat/0309042v1

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Sep 18, 2013
09/13

by
J. B. Kogut; D. K. Sinclair

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We have simulated QCD at a finite chemical potential $\mu_I$ for isospin ($I_3$) to probe part of the phase diagram for nuclear matter. Preliminary results suggest that for $\mu_I > \mu_c$, this theory forms a charged pion condensate which spontaneously breaks $I_3$, and the isospin density is non zero.

Source: http://arxiv.org/abs/hep-lat/0110022v1

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Sep 18, 2013
09/13

by
J. B. Kogut; D. K. Sinclair

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We simulate 3-flavour lattice QCD at finite temperature and isospin chemical potential $\mu_I$. In particular we study the nature of the finite temperature transition for quark masses close to the critical mass at which this transition for zero chemical potentials changes from a first order transition to a crossover. We find that the Binder cumulants, used to determine the position of this transition, have very strong dt dependence. This leads us to an estimate of the critical mass which is...

Source: http://arxiv.org/abs/hep-lat/0509095v1

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Sep 18, 2013
09/13

by
J. B. Kogut; D. K. Sinclair

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We have simulated lattice QCD directly in the chiral limit of zero quark mass by adding an additional, irrelevant 4-fermion interaction to the standard action. Using lattices having temporal extent of six and spatial extents of twelve and eighteen, we find that the theory with 2 massless staggered quark flavors has a second order finite temperature phase transition. The critical exponents $\beta_{mag}$, $\delta$ and $\nu$ are measured and favour tricritical behaviour over that expected by...

Source: http://arxiv.org/abs/hep-lat/0005007v2

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2.0

Jun 28, 2018
06/18

by
D. K. Sinclair; J. B. Kogut

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QCD at non-zero chemical potential ($\mu$) for quark number has a complex fermion determinant and thus standard simulation methods for lattice QCD cannot be applied. We therefore simulate this theory using the Complex-Langevin algorithm with Gauge Cooling in addition to adaptive methods, to prevent runaway behaviour. Simulations are performed at zero temperature on a $12^4$ lattice with 2 quarks which are light enough that $m_N/3$ is significantly larger than $m_\pi/2$. Preliminary results are...

Topic: High Energy Physics - Lattice

Source: http://arxiv.org/abs/1510.06367

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Sep 23, 2013
09/13

by
J. -F. Lagae; D. K. Sinclair

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We study the chiral properties of domain-wall quarks at high temperatures on an ensemble of quenched configurations. Low lying eigenmodes of the Dirac operator are calculated and used to check the extent to which the Atiyah-Singer index theorem is obeyed on lattices with finite $N_5$. We calculate the connected and disconnected screening propagators for the lowest mass scalar and pseudoscalar mesons in the sectors of different topological charge and note that they behave as expected. Separating...

Source: http://arxiv.org/abs/hep-lat/9909097v1

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Sep 20, 2013
09/13

by
J. B. Kogut; D. K. Sinclair

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The Rational Hybrid Monte Carlo (RHMC) algorithm extends the Hybrid Monte Carlo algorithm for lattice QCD simulations to situations involving fractional powers of the determinant of the quadratic Dirac operator. This avoids the updating increment ($dt$) dependence of observables which plagues the Hybrid Molecular-dynamics (HMD) method. The RHMC algorithm uses rational approximations to fractional powers of the quadratic Dirac operator. Such approximations are only available when positive upper...

Source: http://arxiv.org/abs/hep-lat/0608017v1

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Sep 23, 2013
09/13

by
J. B. Kogut; D. K. Sinclair

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We simulate lattice QCD with an irrelevant chiral 4-fermion interaction which allows us to simulate at zero quark mass. This enables us to study the finite-temperature chiral-symmetry-restoring phase transition for 2 massless quark flavours, which is believed to be second order. In particular, it enables us to estimate the critical exponents which characterize the universality class of this transition. Our earlier simulations on $N_t=4$ and $N_t=6$ lattices revealed that finite lattice-spacing...

Source: http://arxiv.org/abs/hep-lat/0408003v1

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Sep 19, 2013
09/13

by
J. B. Kogut; D. K. Sinclair

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We simulate lattice QCD at a finite chemical potential $\mu_I$ for isospin ($I_3$) at zero and finite temperatures. At some $\mu_I=\mu_c$ QCD has a second order transition with mean-field critical exponents to a state where ($I_3$) is broken spontaneously by a charged pion condensate. Heating the system with $\mu_I > \mu_c$ we find there is some temperature at which this condensate evaporates. This transition appears to be second order and mean-field at lower $\mu_I$ values, and first order...

Source: http://arxiv.org/abs/hep-lat/0209054v1

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Sep 22, 2013
09/13

by
J. B. Kogut; D. K. Sinclair

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We simulate lattice QCD with 2 flavours of massless quarks on lattices of temporal extent N_t=8, to study the finite temperature transition from hadronic matter to a quark-gluon plasma. A modified action which incorporates an irrelevant chiral 4-fermion interaction is used, which allows simulations at zero quark mass. We obtain excellent fits of the chiral condensates to the magnetizations of a 3-dimensional O(2) spin model on lattices small enough to model the finite size effects. This gives...

Source: http://arxiv.org/abs/hep-lat/0603021v2

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Sep 18, 2013
09/13

by
J. -F. Lagae; D. K. Sinclair

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We investigate the properties of domain wall fermions on a set of quenched configurations at non-zero temperature. In particular, we compute the low lying eigenvalues of the DWF operator and study their relation with topology, level crossings and chiral symmetry breaking. We also measure the screening correlators and discuss the dependence on the extent of the extra dimension and the quark mass.

Source: http://arxiv.org/abs/hep-lat/9809134v1

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Sep 18, 2013
09/13

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J. B. Kogut; D. K. Sinclair

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We simulate 3-flavour lattice QCD at small isospin chemical potential $\mu_I$ and finite temperature $T$. At $\mu_I=0$ there is a critical mass $m_c$ where the finite-temperature transition changes from first order to a crossover. We measure the $\mu_I$ dependence of the transition $\beta$ ($\beta_c$) for $m$ close to $m_c$. $\beta_c$ and hence $T_c$ decrease slowly with increasing $\mu_I$. $\beta_c$ at finite $\mu_I$ is in good agreement $\beta_c$ at finite $\mu$ (quark-number chemical...

Source: http://arxiv.org/abs/hep-lat/0504003v1

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4.0

Jun 30, 2018
06/18

by
J. B. Kogut; D. K. Sinclair

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We have been studying QCD with 2 flavours of colour-sextet quarks as a candidate walking-Technicolor theory using lattice-QCD simulations. The evolution of the coupling constant with lattice spacing is measured at the finite-temperature chiral transition to determine if this theory is asymptotically free and hence QCD-like. The lattice spacing is varied by changing the number of lattice sites, $N_t$, in the Euclidean time direction. QCD with 3 flavours is studied for comparison. Since this...

Topic: High Energy Physics - Lattice

Source: http://arxiv.org/abs/1406.1524

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Sep 23, 2013
09/13

by
D. K. Sinclair; J. B. Kogut

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QCD with 2 massless colour-sextet quarks is studied as a model of Walking Technicolor. We simulate lattice QCD with 2 light color-sextet staggered quarks at finite temperature, and use the dependence of the coupling at the chiral transition on the temporal extent, $N_t$, of the lattice in lattice units to study the running of the bare lattice coupling with lattice spacing. Our goal is to determine whether this theory is QCD-like and `walks', or if it is conformal. If it is QCD-like, the...

Source: http://arxiv.org/abs/1111.2319v1

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Sep 19, 2013
09/13

by
D. K. Sinclair; J. B. Kogut

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We study QCD with two flavours of colour-sextet quarks as a candidate walking-Technicolor theory. We simulate lattice QCD with two flavours of colour-sextet staggered quarks at finite temperatures to observe the scales of confinement and chiral-symmetry breaking. These should give us some indication as to whether the massless theory has an infrared fixed point making it a conformal field theory, or whether it exhibits confinement and chiral symmetry breaking with a slowly varying coupling...

Source: http://arxiv.org/abs/0909.2019v2

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Jul 20, 2013
07/13

by
D. K. Sinclair; J. B. Kogut

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We consider 3-flavour lattice QCD with a finite chemical potential mu_I for isospin, close to the finite temperature transition from hadronic matter to a quark-gluon plasma. In this region one can argue that the position and probably the nature of this transition mimic those at finite quark-number chemical potential mu. The quark mass is chosen to be close to the critical mass at zero chemical potentials. Since the Binder cumulants used to determine the nature of this transition in HMD(R)...

Source: http://arxiv.org/abs/hep-lat/0609041v1

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Jun 28, 2018
06/18

by
J. B. Kogut; D. K. Sinclair

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QCD with 2 flavours of massless colour-sextet quarks is studied as a possible walking-Technicolor candidate. We simulate the lattice version of this model at finite temperatures near to the chiral-symmetry restoration transition, to determine whether it is indeed a walking theory (QCD-like with a running coupling which evolves slowly over an appreciable range of length scales) or if it has an infrared fixed point, making it a conformal field theory. The lattice spacing at this transition is...

Topic: High Energy Physics - Lattice

Source: http://arxiv.org/abs/1507.00375

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Sep 19, 2013
09/13

by
J. -F. Lagae; D. K. Sinclair

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We investigate a class of actions for lattice QCD with staggered quarks aimed at reducing the flavour symmetry violations associated with using staggered fermions. These actions replace the gauge field link fields in the quark action with covariantly smeared fields. As such they are an extension of actions considered by the MILC collaboration. We show that such actions systematically reduce flavour symmetry violations in the weak coupling limit. Using the mass splitting between Goldstone and...

Source: http://arxiv.org/abs/hep-lat/9709035v1

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Sep 21, 2013
09/13

by
J. B. Kogut; D. K. Sinclair

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We simulate 2-flavour lattice QCD at finite isospin chemical potential mu_I, for temperatures close to the finite temperature transition from hadronic matter to a quark-gluon plasma. The mu_I dependence of the transition coupling is observed and used to estimate the decrease in the transition temperature with increasing mu_I. These simulations are performed on an 8^3 times 4 lattice at 3 different quark masses. Our estimate of the magnitude of the fluctuations of the phase of the fermion...

Source: http://arxiv.org/abs/hep-lat/0407027v1

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Sep 23, 2013
09/13

by
J. B. Kogut; D. K. Sinclair

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Lattice QCD with staggered quarks is augmented by the addition of a chiral 4-fermion interaction. The Dirac operator is now non-singular at $m_q=0$, decreasing the computing requirements for light quark simulations by at least an order of magnitude. We present preliminary results from simulations at finite and zero temperatures for $m_q=0$, with and without gauge fields.

Source: http://arxiv.org/abs/hep-lat/9607083v2

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Sep 23, 2013
09/13

by
J. -F. Lagae; D. K. Sinclair

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We introduce a new class of actions for staggered quarks in lattice QCD which significantly reduce flavour symmetry violations in the pion mass spectrum. An action introduced by the MILC collaboration for the same purpose is seen to be a special case. We discus how such actions arise from a systematic attempt to reduce flavour symmetry violations in the weak coupling limit. It is shown that for quenched lattice QCD at 6/g^2=5.7, representative actions of this class give a considerable reduction...

Source: http://arxiv.org/abs/hep-lat/9806014v1

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Sep 23, 2013
09/13

by
J. B. Kogut; D. K. Sinclair

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We continue our lattice simulations of QCD with 2 flavours of colour-sextet quarks as a model for conformal or walking technicolor. A 2-loop perturbative calculation of the $\beta$-function which describes the evolution of this theory's running coupling constant predicts that it has a second zero at a finite coupling. This non-trivial zero would be an infrared stable fixed point, in which case the theory with massless quarks would be a conformal field theory. However, if the interaction between...

Source: http://arxiv.org/abs/1105.3749v3

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Sep 18, 2013
09/13

by
D. K. Sinclair; J. B. Kogut

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We study QCD with 2 colour-sextet quarks as a model for walking Technicolor, using lattice gauge theory simulations (RHMC) at finite temperature. Our goal is to determine if the massless theory is QCD-like (confining, with spontaneously-broken chiral symmetry) with a slowly varying coupling (walks) or if it is a conformal field theory. We do this by simulating the theory at finite temperature and observing how the coupling at the chiral-symmetry restoration temperature depends on the temporal...

Source: http://arxiv.org/abs/1211.0712v1

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Sep 21, 2013
09/13

by
John B. Kogut; Dominique Toublan; D. K. Sinclair

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SU(2) lattice gauge theory with four flavors of quarks is studied at nonzero chemical potential $\mu$ and temperature $T$ by computer simulation and Effective Lagrangian techniques. Simulations are done on $8^4$, $8^3 \times 4$ and $12^3 \times 6$ lattices and the diquark condensate, chiral order parameter, Wilson line, fermion energy and number densities are measured. Simulations at a fixed, nonzero quark mass provide evidence for a tricritical point in the $\mu$-$T$ plane associated with...

Source: http://arxiv.org/abs/hep-lat/0104010v1

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Sep 18, 2013
09/13

by
G. T. Bodwin; S. Kim; D. K. Sinclair

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We use the Bodwin-Braaten-Lepage factorization scheme to separate the long- and short-distance factors that contribute to the decay rates of $\Upsilon$, $\eta_b$ (S-wave) and $\chi_b$,$h_b$ (P-wave). The long distance matrix elements are calculated on the lattice in the quenched approximation using a non-relativistic formulation of the $b$ quark dynamics.

Source: http://arxiv.org/abs/hep-lat/9412011v1

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Sep 17, 2013
09/13

by
J. B. Kogut; D. Toublan; D. K. Sinclair

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We examine the spectrum of 2-colour lattice QCD with 4 continuum flavours at a finite chemical potential ($\mu$) for quark-number, on a $12^3 \times 24$ lattice. First we present evidence that the system undergoes a transition to a state with a diquark condensate, which spontaneously breaks quark number at $\mu=m_\pi/2$, and that this transition is mean field in nature. We then examine the 3 states that would be Goldstone bosons at $\mu=0$ for zero Dirac and Majorana quark masses. The...

Source: http://arxiv.org/abs/hep-lat/0305003v1

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Sep 18, 2013
09/13

by
G. T. Bodwin; D. K. Sinclair; S. Kim

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We calculate the long-distance matrix elements for the decays of the lowest-lying S- and P-wave states of charmonium and bottomonium in quenched lattice QCD, using a nonrelativistic formulation for the heavy quarks. (The short-distance coefficients are known from perturbation theory.) In particular, we present the first calculation from QCD first principles of the color-octet contribution to P-wave decay---a contribution that is absent in potential models. We also give the relations between the...

Source: http://arxiv.org/abs/hep-lat/9605023v2

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Sep 21, 2013
09/13

by
G. T. Bodwin; D. K. Sinclair; S. Kim

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We calculate the NRQCD matrix elements for the decays of the lowest-lying S- and P-wave states of charmonium and bottomonium in quenched lattice QCD. We also compute the one-loop relations between the lattice and continuum matrix elements.

Source: http://arxiv.org/abs/hep-ph/9609371v1

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Sep 24, 2013
09/13

by
Geoffrey T. Bodwin; Jungil Lee; D. K. Sinclair

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We compute spin-dependent matrix elements for decays of S-wave quarkonia in lattice NRQCD. They appear to be in approximate agreement with the velocity-scaling rules of NRQCD.

Source: http://arxiv.org/abs/hep-lat/0412006v1

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Jul 20, 2013
07/13

by
G. T. Bodwin; D. K. Sinclair; S. Kim

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We calculate the long-distance matrix elements for the decays of the Upsilon (eta_b) and chi_b (h_b) states in lattice QCD with two flavors of light dynamical quarks. We relate the lattice matrix elements to their continuum counterparts through one-loop order in perturbation theory. In the case of the leading S-wave matrix element, we compare our result with a phenomenological value that we extract from the experimental leptonic decay rate by using the theoretical expression for the decay rate,...

Source: http://arxiv.org/abs/hep-lat/0107011v2

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Sep 22, 2013
09/13

by
John B. Kogut; Dominique Toublan; D. K. Sinclair

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SU(2) lattice gauge theory with four flavors of quarks is simulated at nonzero chemical potential $\mu$ and temperature $T$ and the results are compared to the predictions of Effective Lagrangians. Simulations on $16^4$ lattices indicate that at zero $T$ the theory experiences a second order phase transition to a diquark condensate state. Several methods of analysis, including equation of state fits suggested by Chiral Perturbation Theory, suggest that mean-field scaling describes this critical...

Source: http://arxiv.org/abs/hep-lat/0205019v1