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Search: authors:"Nicolas Garron"

9 papers found.
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Controlling the sign problem in finite-density quantum field theory

Quantum field theories at finite matter densities generically possess a partition function that is exponentially suppressed with the volume compared to that of the phase quenched analog. The smallness arises from an almost uniform distribution for the phase of the fermion determinant. Large cancellations upon integration is the origin of a poor signal to noise ratio. We study three ...

Anatomy of the sign-problem in heavy-dense QCD

QCD at finite densities of heavy quarks is investigated using the density-of-states method. The phase factor expectation value of the quark determinant is calculated to unprecedented precision as a function of the chemical potential. Results are validated using those from a reweighting approach where the latter can produce a significant signal-to-noise ratio. We confirm the ...

Neutral kaon mixing beyond the Standard Model with nf = 2 + 1 chiral fermions. Part 1: bare matrix elements and physical results

We compute the hadronic matrix elements of the four-quark operators relevant for \( {K}^0-{\overline{K}}^0 \) mixing beyond the Standard Model. Our results are from lattice QCD simulations with n f = 2 + 1 flavours of domain-wall fermion, which exhibit continuum-like chiral-flavour symmetry. The simulations are performed at two different values of the lattice spacing (a ∼ 0.08 and ...

Non-perturbative tests of continuum HQET through small-volume two-flavour QCD

We study the heavy quark mass dependence of selected observables constructed from heavy-light meson correlation functions in small-volume two-flavour lattice QCD after taking the continuum limit. The light quark mass is tuned to zero, whereas the range of available heavy quark masses m h covers a region extending from around the charm to beyond the bottom quark mass scale. This ...

Pion couplings to the scalar \(B\) meson

We present two-flavor lattice QCD estimates of the hadronic couplings \(g_{B^*_0 B \pi }\) and \(g_{B_1^* B_0^* \pi }\) that parametrize the non-leptonic decays \(B^*_0 \rightarrow B \pi \) and \(B^*_1 \rightarrow B_0^* \pi \). We use CLS two-flavor gauge ensembles. Our framework is the Heavy Quark Effective Theory (HQET) in the static limit and solving a Generalized Eigenvalue ...

Parameters of heavy quark effective theory from N f = 2 lattice QCD

We report on a non-perturbative determination of the parameters of the lattice Heavy Quark Effective Theory (HQET) Lagrangian and of the time component of the heavy-light axial-vector current with N f = 2 flavors of massless dynamical quarks. The effective theory is considered at the 1/m h order, and the heavy mass m h covers a range from slightly above the charm to beyond the ...

HQET at order 1/m: I. Non-perturbative parameters in the quenched approximation

We determine non-perturbatively the parameters of the lattice HQET Lagrangian and those of the time component of the heavy-light axial-vector current in the quenched approximation. The HQET expansion includes terms of order 1/m b. Our results allow to compute, for example, the heavy-light spectrum and B-meson decay constants in the static approximation and to order 1/m b in HQET. ...

HQET at order 1/m: III. Decay constants in the quenched approximation

We report on the computation of the Bs meson decay constant in Heavy Quark Effective Theory on the lattice. The next to leading order corrections in the HQET expansion are included non-perturbatively. We estimate higher order contributions to be very small. The results are extrapolated to the continuum limit, the main systematic error affecting the computation is therefore the ...

HQET at order 1/m: II. Spectroscopy in the quenched approximation

Using Heavy Quark Effective Theory with non-perturbatively determined parameters in a quenched lattice calculation, we evaluate the splittings between the ground state and the first two radially excited states of the Bs system at static order. We also determine the splitting between first excited and ground state, and between the B s * and Bs ground states to order 1/m b . The ...