It is now well established that superconducting cuprates support a charge-density-wave state in the so-called underdoped region of their phase diagram. We investigate the possibility of charge order in the square-lattice Hubbard model, both alone and in coexistence with d-wave superconductivity. The charge order has a period of 4 in one direction, is centered on bonds, and has a d form factor. We use the variational cluster approximation, an approach based on a rigorous variational principle that treats short-range correlations exactly, with two clusters of size 2 \× 6 that together tile the infinite lattice and provide a nonbiased unit for a period-4 bond-density wave (BDW). We find that the BDW exists in a finite range of hole doping and increases in strength from U = 5 to U = 8. Its location and intensity depend strongly on the band dispersion. When probed simultaneously with d-wave superconductivity, the energy is sometimes lowered by the presence of both phases, depending on the interaction strength. Whenever they coexist, a pair-density wave (a modulation of superconducting pairing with the same period and form factor as the BDW) also exists.

}, doi = {10.1103/PhysRevB.95.115127}, url = {http://journals.aps.org/prb/pdf/10.1103/PhysRevB.95.115127}, author = {Faye, J P L and D. S{\'e}n{\'e}chal} } @article {9314, title = {Phenomenological theories of the low-temperature pseudogap: Hall number, specific heat, and Seebeck coefficient}, journal = {Phys. Rev. B}, volume = {96}, year = {2017}, month = {Sep}, pages = {125139 Editor{\textquoteright}s choice}, doi = {10.1103/PhysRevB.96.125139}, url = {https://link.aps.org/doi/10.1103/PhysRevB.96.125139}, author = {Verret, S. and Simard, O. and Charlebois, M. and D. S{\'e}n{\'e}chal and A.-M. S. Tremblay} } @article {9317, title = {Pseudogap-to-metal transition in the anisotropic two-dimensional Hubbard model}, journal = {Physical Review B}, volume = {96}, year = {2017}, issn = {2469-9950, 2469-9969}, doi = {10.1103/PhysRevB.96.195114}, url = {https://link.aps.org/doi/10.1103/PhysRevB.96.195114}, author = {Faye, J. P. L. and D. S{\'e}n{\'e}chal} } @article {9214, title = {{Subgap structures and pseudogap in cuprate superconductors: Role of density waves}}, journal = {Phys. Rev. B}, volume = {95}, year = {2017}, pages = {054518}, abstract = {In scanning tunneling microscopy conductance curves, the superconducting gap of cuprates is sometimes accompanied by small subgap structures at very low energy. This was documented early on near vortex cores and later at zero magnetic field. Using mean-field toy models of coexisting d-wave superconductivity, d-form-factor density wave, and extended s-wave pair density wave (s PDW), we find agreement with this phenomenon, with s PDW playing a critical role. We explore the high variability of the gap structure with changes in band structure and density wave (DW) wave vector, thus explaining why subgap structures may not be a universal feature in cuprates. In the absence of nesting, nonsuperconducting results never show signs of pseudogap, even for large density wave magnitudes, therefore reinforcing the idea of a distinct origin for the pseudogap, beyond mean-field theory. Therefore, we also briefly consider the effect of DWs on a preexisting pseudogap.

}, doi = {10.1103/PhysRevB.95.054518}, author = {Verret, S and Charlebois, M and D. S{\'e}n{\'e}chal and A.-M. S. Tremblay} } @article {8971, title = {{Kekul{\'e} superconductivity and antiferromagnetism on the graphene lattice}}, journal = {Phys. Rev. B}, volume = {93}, year = {2016}, chapter = {155149}, doi = {10.1103/PhysRevB.93.155149}, author = {Faye, J. P. L. and Diarra, M. N. and D. S{\'e}n{\'e}chal} } @article {9189, title = {Mott transition and magnetism on the anisotropic triangular lattice}, journal = {Phys. Rev. B}, volume = {94}, year = {2016}, month = {Dec}, pages = {245133}, doi = {10.1103/PhysRevB.94.245133}, url = {http://link.aps.org/doi/10.1103/PhysRevB.94.245133}, author = {Acheche, S. and Reymbaut, A. and Charlebois, M. and D. S{\'e}n{\'e}chal and A.-M. S. Tremblay} } @article {PhysRevB.93.075131, title = {Quantum cluster approach to the spinful Haldane-Hubbard model}, journal = {Phys. Rev. B}, volume = {93}, year = {2016}, month = {Feb}, pages = {075131}, publisher = {American Physical Society}, doi = {10.1103/PhysRevB.93.075131}, url = {http://link.aps.org/doi/10.1103/PhysRevB.93.075131}, author = {Wu, Jingxiang and Faye, Jean Paul Latyr and D. S{\'e}n{\'e}chal and Maciejko, Joseph} } @article {8795, title = {Chiral triplet superconductivity on the graphene lattice}, journal = {Physical Review B}, volume = {92}, year = {2015}, month = {8/2015}, issn = {1550-235X}, doi = {10.1103/PhysRevB.92.085121}, author = {Faye, J. P. L. and P. Sahebsara and D. S{\'e}n{\'e}chal} } @article {8782, title = {d-wave superconductivity in coupled ladders}, journal = {Physical Review B}, volume = {91}, year = {2015}, month = {5/2015}, issn = {1550-235X}, doi = {10.1103/PhysRevB.91.195126}, author = {Faye, J. P. L. and Hassan, S. R. and Sriluckshmy, P. V. and Baskaran, G. and D. S{\'e}n{\'e}chal} } @article {PhysRevB.91.035132, title = {Impurity-induced magnetic moments on the graphene-lattice Hubbard model: An inhomogeneous cluster dynamical mean-field theory study}, journal = {Phys. Rev. B}, volume = {91}, year = {2015}, month = {Jan}, pages = {035132}, publisher = {American Physical Society}, doi = {10.1103/PhysRevB.91.035132}, url = {http://link.aps.org/doi/10.1103/PhysRevB.91.035132}, author = {Charlebois, M. and D. S{\'e}n{\'e}chal and Gagnon, A.-M. and A.-M. S. Tremblay} } @inbook {Senechal:2015rm, title = {Quantum cluster methods: {CPT and CDMFT}}, booktitle = {Many-Body Physics: From Kondo to Hubbard, Lecture Notes of the Autumn School on Correlated Electrons 2015}, volume = {5}, year = {2015}, pages = {13.1 - 13.32}, publisher = {Forschungszentrum J{\"u}lich}, organization = {Forschungszentrum J{\"u}lich}, chapter = {13}, author = {D. S{\'e}n{\'e}chal}, editor = {Pavarini, Eva and Koch, Erik and Piers Coleman} } @article {8570, title = {Topological phases of the Kitaev-Hubbard model at half filling}, journal = {Physical Review B}, volume = {89}, year = {2014}, month = {3/2014}, issn = {1550-235X}, doi = {10.1103/PhysRevB.89.115130}, author = {Faye, J. P. L. and D. S{\'e}n{\'e}chal and Hassan, S. R.} } @article {8314, title = {Absence of Spin Liquid in Nonfrustrated Correlated Systems}, journal = {Physical Review Letters}, volume = {110}, year = {2013}, month = {2/2013}, issn = {1079-7114}, doi = {10.1103/PhysRevLett.110.096402}, author = {Hassan, S. R. and D. S{\'e}n{\'e}chal} } @article {Hassan:2013lh, title = {Hassan and S{\'e}n{\'e}chal Reply:}, journal = {Physical Review Letters}, volume = {111}, number = {2}, year = {2013}, note = {cited By (since 1996)0}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84880559675\&partnerID=40\&md5=8f53efbdf35067625da102ef8c9d1990}, author = {Hassan, S. R. and D. S{\'e}n{\'e}chal} } @article {Charlebois:2013vn, title = {Mott p-n junctions in layered materials}, journal = {Phys. Rev. B}, volume = {87}, year = {2013}, month = {Jan}, pages = {035137}, publisher = {American Physical Society}, doi = {10.1103/PhysRevB.87.035137}, url = {http://link.aps.org/doi/10.1103/PhysRevB.87.035137}, author = {Charlebois, M. and Hassan, S. R. and Karan, R. and D. S{\'e}n{\'e}chal and A.-M. S. Tremblay} } @article {8369, title = {Quarter-filled Kitaev-Hubbard model: A quantum Hall state in an optical lattice}, journal = {Physical Review B}, volume = {88}, year = {2013}, month = {7/2013}, issn = {1550-235X}, doi = {10.1103/PhysRevB.88.045301}, author = {Hassan, S. R. and Goyal, Sandeep and Shankar, R. and D. S{\'e}n{\'e}chal} } @article {PhysRevB.87.075123, title = {Resilience of d-wave superconductivity to nearest-neighbor repulsion}, journal = {Phys. Rev. B}, volume = {87}, year = {2013}, month = {Feb}, pages = {075123}, publisher = {American Physical Society}, doi = {10.1103/PhysRevB.87.075123}, url = {http://link.aps.org/doi/10.1103/PhysRevB.87.075123}, author = {D. S{\'e}n{\'e}chal and Day, A. G. R. and Bouliane, V. and A.-M. S. Tremblay} } @article {8246, title = {Stable Algebraic Spin Liquid in a Hubbard Model}, journal = {Physical Review Letters}, volume = {110}, year = {2013}, month = {1/2013}, issn = {1079-7114}, doi = {10.1103/PhysRevLett.110.037201}, author = {Hassan, S. and Sriluckshmy, P. and Goyal, Sandeep and Shankar, R. and D. S{\'e}n{\'e}chal} } @inbook {Senechal:2011kx, title = {Cluster Dynamical Mean Field Theory}, booktitle = {Theoretical methods for Strongly Correlated Systems}, series = {Springer Series in Solid-State Sciences}, volume = {171}, year = {2012}, pages = {341{\textendash}370}, publisher = {Springer}, organization = {Springer}, chapter = {11}, author = {D. S{\'e}n{\'e}chal}, editor = {Adolfo Avella and Ferdinando Mancini} } @inbook {Senechal:2011vn, title = {Cluster Perturbation Theory}, booktitle = {Theoretical methods for Strongly Correlated Systems}, series = {Springer Series in Solid-State Sciences}, volume = {171}, year = {2012}, pages = {237{\textendash}269}, publisher = {Springer}, organization = {Springer}, chapter = {8}, author = {D. S{\'e}n{\'e}chal}, editor = {Adolfo Avella and Ferdinando Mancini} } @article {7570, title = {d-wave superconductivity on the checkerboard Hubbard model at weak and strong coupling}, journal = {Physical Review B}, volume = {84}, year = {2011}, month = {2011}, pages = {054545/1--8}, chapter = {054545}, author = {Shiladitya Chakraborty and D. S{\'e}n{\'e}chal and A.-M. S. Tremblay} } @article {Senechal:2011fk, title = {Superconductivity in the subatomic realm}, journal = {Physics in Canada/La physique au Canada}, volume = {67}, number = {2}, year = {2011}, month = {April-June}, author = {D. S{\'e}n{\'e}chal} } @article {Payeur:2011fk, title = {Variational cluster approximation study of the one-dimensional Holstein-Hubbard model at half filling}, journal = {Phys. Rev. B}, volume = {83}, number = {3}, year = {2011}, month = {Jan}, pages = {033104}, publisher = {American Physical Society}, doi = {10.1103/PhysRevB.83.033104}, author = {Payeur, Alexandre and D. S{\'e}n{\'e}chal} } @article {Senechal:2010fk, title = {Bath optimization in the cellular dynamical mean-field theory}, journal = {Physical Review B}, volume = {81}, number = {23}, year = {2010}, month = {Jun}, pages = {235125}, publisher = {American Physical Society}, keywords = {Sans titre}, doi = {10.1103/PhysRevB.81.235125}, author = {D. S{\'e}n{\'e}chal} } @article {Okamoto:2010tv, title = {Dynamical electronic nematicity from Mott physics}, journal = {Physical Review B (Editor{\textquoteright}s choice)}, volume = {82}, number = {18}, year = {2010}, month = {2010}, pages = {180511(R)/1-4}, abstract = {Very large anisotropies in transport quantities have been observed in the presence of very small in-plane structural anisotropy in many strongly correlated electron materials. By studying the two-dimensional Hubbard model with dynamical-mean-field theory for clusters, we show that such large anisotropies can be induced without static stripe order if the interaction is large enough to yield a Mott transition. Anisotropy decreases at large frequency. The maximum effect on conductivity anisotropy occurs in the underdoped regime, as observed in high-temperature superconductors.

}, author = {Okamoto, S. and D. S{\'e}n{\'e}chal and Civelli, M. and A.-M. S. Tremblay} } @article {Balzer:2009vo, title = {First-order Mott transition at zero temperature in two dimensions: Variational plaquette study}, journal = {Europhysics Letters}, volume = {85}, number = {1}, year = {2009}, month = {2009}, pages = {17002/1-6}, abstract = {The nature of the metal-insulator Mott transition at zero temperature has been discussed for a number of years. Whether it occurs through a quantum critical point or through a first-order transition is expected to profoundly influence the nature of the finite-temperature phase diagram. In this paper, we study the zero temperature Mott transition in the two-dimensional Hubbard model on the square lattice with the variational cluster approximation. This takes into account the influence of antiferromagnetic short-range correlations. By contrast to single-site dynamical mean-field theory, the transition turns out to be first order even at zero temperature. Copyright (C) EPLA, 2009

}, author = {Balzer, M. and B. Kyung and D. S{\'e}n{\'e}chal and A.-M. S. Tremblay and Potthoff, M.} } @article {Kyung:2009vq, title = {Pairing dynamics in strongly correlated superconductivity}, journal = {Physical Review B}, volume = {80}, number = {20}, year = {2009}, month = {2009}, pages = {205109/1-8}, abstract = {Confirmation of the phononic origin of Cooper pair formation in superconductors came with the demonstration that the interaction was retarded and that the corresponding energy scales were associated with phonons. Using cellular dynamical mean-field theory for the two-dimensional Hubbard model, we identify such retardation effects in d-wave pairing and associate the corresponding energy scales with short-range spin fluctuations. We find which frequencies are relevant for pairing as a function of interaction strength and doping and show that the disappearance of superconductivity on the overdoped side coincides with the disappearance of the low-energy feature in the antiferromagnetic fluctuations, as observed in neutron-scattering experiments.

}, author = {B. Kyung and D. S{\'e}n{\'e}chal and A.-M. S. Tremblay} } @article {Kancharla:2008ot, title = {Anomalous superconductivity and its competition with antiferromagnetism in doped Mott insulators}, journal = {Physical Review B}, volume = {77}, number = {18}, year = {2008}, month = {2008}, pages = {184516/1-12}, abstract = {Proximity to a Mott insulating phase is likely to be an important physical ingredient of a theory that aims to describe high-temperature superconductivity in the cuprates. Quantum cluster methods are well suited to describe the Mott phase. Hence, as a step toward a quantitative theory of the competition between antiferromagnetism and d-wave superconductivity in the cuprates, we use cellular dynamical mean-field theory to compute zero-temperature properties of the two-dimensional square lattice Hubbard model. The d-wave order parameter is found to scale like the superexchange coupling J for on-site interaction U comparable to or larger than the bandwidth. The order parameter also assumes a dome shape as a function of doping, while, by contrast, the gap in the single-particle density of states decreases monotonically with increasing doping. In the presence of a finite second neighbor hopping t\&$\#$39;, the zero-temperature phase diagram displays the electron-hole asymmetric competition between antiferromagnetism and superconductivity that is observed experimentally in the cuprates. Adding realistic third neighbor hopping t \&$\#$39;\&$\#$39; improves the overall agreement with the experimental phase diagram. Since band parameters can vary depending on the specific cuprate considered, the sensitivity of the theoretical phase diagram to band parameters challenges the commonly held assumption that the doping Vs T-c/T-c(max) phase diagram of the cuprates is universal. The calculated angle-resolved photoemission spectrum displays the observed electron-hole asymmetry. The tendency to homogeneous coexistence of the superconducting and antiferromagnetic order parameters is stronger than observed in most experiments but consistent with many theoretical results and with experiments in some layered high-temperature superconductors. Clearly, our calculations reproduce important features of d-wave superconductivity in the cuprates that would otherwise be considered anomalous from the point of view of the standard Bardeen-Cooper-Schrieffer approach. At strong coupling, d-wave superconductivity and antiferromagnetism naturally appear as two equally important competing instabilities of the normal phase of the same underlying Hamiltonian.

}, author = {Kancharla, S. S. and B. Kyung and D. S{\'e}n{\'e}chal and Civelli, M. and Capone, M. and Kotliar, G. and A.-M. S. Tremblay} } @article {Nevidomskyy:2008sn, title = {Convexity of the self-energy functional in the variational cluster approximation}, journal = {Physical Review B}, volume = {77}, number = {7}, year = {2008}, month = {2008}, pages = {075105/1-12}, abstract = {In the variational cluster approximation (VCA) (or variational cluster perturbation theory), widely used to study the Hubbard model, a fundamental problem that renders variational solutions difficult in practice is its known lack of convexity at stationary points, i.e., the physical solutions can be saddle points rather than extrema of the self-energy functional. Here, we suggest two different approaches to construct a convex functional Omega[Sigma]. In the first approach, one can show analytically that in the approximation where the irreducible particle-hole vertex depends only on center of mass coordinates, the functional is convex away from phase transitions in the corresponding channel. Numerical tests on a tractable version of that functional show that convexity can be a nuisance when looking for instabilities both in the pairing and particle-hole channels. Therefore, an alternative phenomenological functional is proposed. Convexity is explicitly enforced only with respect to a restricted set of variables, such as the cluster chemical potential that is known to be otherwise problematic. Numerical tests show that our functional is convex at the physical solutions of VCA and allows second-order phase transitions in the pairing channel as well. This opens the way to the use of more efficient algorithms to find solutions of the VCA equations.

}, author = {Nevidomskyy, A. H. and D. S{\'e}n{\'e}chal and A.-M. S. Tremblay} } @article {Sahebsara:2008fv, title = {Hubbard Model on the Triangular Lattice: Spiral Order and Spin Liquid}, journal = {Physical Review Letters}, volume = {100}, year = {2008}, pages = {136402}, keywords = {Sans titre}, author = {P. Sahebsara and D. S{\'e}n{\'e}chal} } @article {Nevidomskyy:2008af, title = {Magnetism and d-wave superconductivity on the half-filled square lattice with frustration}, journal = {Physical Review B}, volume = {77}, number = {6}, year = {2008}, month = {2008}, pages = {064427/1-13}, abstract = {The role of frustration and interaction strength on the half-filled Hubbard model is studied on the square lattice with nearest- and next-nearest-neighbor hoppings t and t(\&$\#$39;) using the variational cluster approximation (VCA). At half-filling, we find two phases with long-range antiferromagnetic (AF) order: the usual Neel phase, stable at small frustration t(\&$\#$39;)/t, and the so-called collinear (or superantiferromagnet) phase with ordering wave vector (pi,0) or (0,pi), stable for large frustration. These are separated by a phase with no detectable long-range magnetic order. We also find the d-wave superconducting (SC) phase (d(x)(2)-y(2)), which is favored by frustration if it is not too large. Intriguingly, there is a broad region of coexistence where both AF and SC order parameters have nonzero values. In addition, the physics of the metal-insulator transition in the normal state is analyzed. The results obtained with the help of the VCA method are compared with the large-U expansion of the Hubbard model and known results for the frustrated J(1)-J(2) Heisenberg model. These results are relevant for pressure studies of undoped parents of the high-temperature superconductors: we predict that an insulator to d-wave SC transition may appear under pressure.

}, author = {Nevidomskyy, A. H. and Scheiber, C. and D. S{\'e}n{\'e}chal and A.-M. S. Tremblay} } @article {Dienes:2008zm, title = {Is {SUSY} natural?}, journal = {New Journal of Physics}, volume = {10}, number = {8}, year = {2008}, pages = {085003 (10pp)}, abstract = {Space-time supersymmetry (SUSY) is widely believed to play an important role in most fundamental theories of physics, and is usually invoked in order to address problems of naturalness. In this paper, we examine the question of whether SUSY itself is \’natural\’ (i.e. likely to exist as a fundamental component of nature at high-energy scales). Our approach to answering this question is based on a statistical examination of the heterotic string landscape, and our conclusion is that SUSY is an exceedingly rare phenomenon. We also find that the likelihood of SUSY appearing at the string scale is dependent on the gauge symmetries present at the string scale, with certain gauge groups strongly favoring the appearance of {\\cal N} = 1 SUSY and others not. This paper summarizes several recent papers, yet also contains some new results. In particular, one new result is that the heterotic landscape appears to favor either the non-supersymmetric Standard Model or an {\\cal N} =1 SUSY GUT gauge group at the string scale; by contrast, the opposite outcomes (namely the minimal supersymmetric Standard Model (MSSM) or a non-supersymmetric GUT) are significantly disfavored.

}, keywords = {Sans titre}, author = {K. Dienes and Michael Lennek and D. S{\'e}n{\'e}chal and Vaibhav Wasnik} } @article {Senechal:2008rz, title = {The Variational Cluster Approximation for {Hubbard} Models: Practical Implementation}, journal = {High Performance Computing Systems and Applications, 2008. HPCS 2008. 22nd International Symposium on}, year = {2008}, month = {June}, pages = {9-15}, keywords = {correlated electron systems, frequency- wavevector integrals, high-temperature superconductors, Hubbard model, integral equations, lattice sites, lattice theory, molecular electronic states, organic superconductors, organic superconductorsHubbard models, Sans titre, senechal, variational cluster approximation}, issn = {1550-5243}, doi = {10.1109/HPCS.2008.18}, author = {D. S{\'e}n{\'e}chal} } @article {Dienes:2007ez, title = {Supersymmetry versus gauge symmetry on the heterotic landscape}, journal = {Phys. Rev. D}, volume = {75}, year = {2007}, pages = {126005}, keywords = {Sans titre}, author = {K. Dienes and Michael Lennek and D. S{\'e}n{\'e}chal and Vaibhav Wasnik} } @article {Sahebsara:2006bs, title = {Antiferromagnetism and Superconductivity in Layered Organic Conductors: Variational Cluster Approach}, journal = {Physical Review Letters}, volume = {97}, year = {2006}, pages = {257004}, keywords = {Sans titre}, author = {P. Sahebsara and D. S{\'e}n{\'e}chal} } @article {Sahebsara:2006db, title = {d-wave superconductivity, antiferromagnetism and spin liquid in quasi-two-dimensional organic superconductors}, journal = {Iranian Journal of Physics Research}, volume = {6}, year = {2006}, pages = {179{\textendash}186}, keywords = {Sans titre}, author = {P. Sahebsara and D. S{\'e}n{\'e}chal} } @article {Tremblay:2006jf, title = {Pseudogap and high-temperature superconductivity from weak to strong coupling. Towards a quantitative theory}, journal = {Low Temperature Physics}, volume = {32}, number = {4-5}, year = {2006}, pages = {424{\textendash}451}, abstract = {This is a short review of the theoretical work on the two-dimensional Hubbard model performed in Sherbrooke in the last few years. It is written on the occasion of the twentieth anniversary of the discovery of high-temperature superconductivity. We discuss several approaches, how they were benchmarked and how they agree sufficiently with each other that we can trust that the results are accurate solutions of the Hubbard model. Then comparisons are made with experiment. We show that the Hubbard model does exhibit d-wave superconductivity and antiferromagnetism essentially where they are observed for both hole- and electron-doped cuprates. We also show that the pseudogap phenomenon comes out of these calculations. In the case of electron-doped high temperature superconductors, comparisons with angle-resolved photoemission experiments are nearly quantitative. The value of the pseudogap temperature observed for these compounds in recent photoemission experiments had been predicted by theory before it was observed experimentally. Additional experimental confirmation would be useful. The theoretical methods that are surveyed include mostly the two-particle self-consistent approach, variational cluster perturbation theory (or variational cluster approximation), and cellular dynamical mean-field theory. (c) 2006 American Institute of Physics.

}, author = {A.-M. S. Tremblay and B. Kyung and D. S{\'e}n{\'e}chal} } @article {Kyung:2006tt, title = {Pseudogap induced by short-range spin correlations in a doped Mott insulator}, journal = {Physical Review B}, volume = {73}, number = {16}, year = {2006}, month = {2006}, pages = {1651114/1-6}, abstract = {We study the evolution of a Mott-Hubbard insulator into a correlated metal upon doping in the two-dimensional Hubbard model using the cellular dynamical mean-field theory. Short-range spin correlations create two additional bands apart from the familiar Hubbard bands in the spectral function. Even a tiny doping into this insulator causes a jump of the Fermi energy to one of these additional bands and an immediate momentum-dependent suppression of the spectral weight at this Fermi energy. The pseudogap is closely tied to the existence of these bands. This suggests a strong-coupling mechanism that arises from short-range spin correlations and large scattering rates for the pseudogap phenomenon seen in several cuprates.

}, author = {B. Kyung and Kancharla, S. S. and D. S{\'e}n{\'e}chal and A.-M. S. Tremblay and Civelli, M. and Kotliar, G.} } @article {Hankevych:2006ve, title = {Strong- and weak-coupling mechanisms for pseudogap in electron-doped cuprates}, journal = {Journal of Physics and Chemistry of Solids}, volume = {67}, number = {1-3}, year = {2006}, pages = {189{\textendash}192}, abstract = {Using the two-particle self-consistent approach and cluster perturbation theory for the two-dimensional t-t\&$\#$39;-t\"-U Hubbard model, we discuss weak- and strong-coupling mechanisms for the pseudogap observed in recent angle resolved photoemission spectroscopy on electron-doped cuprates. In the case of the strong-coupling mechanism, which is more relevant near half-filling, the pseudogap can be mainly driven by short-range correlations near the Mott insulator. In the vicinity of optimal doping, where weak-coupling physics is more relevant, large antiferromagnetic correlation lengths, seen in neutron measurements, are the origin of the pseudogap. The t-J model is not applicable in the latter case. (c) 2006 Elsevier Ltd. All rights reserved.

}, author = {Hankevych, V. and B. Kyung and Dare, A. M. and D. S{\'e}n{\'e}chal and A.-M. S. Tremblay} } @article {Senechal:2005, title = {Competition between Antiferromagnetism and Superconductivity in High-${T}_c$ Cuprates}, journal = {Physical Review Letters}, volume = {94}, year = {2005}, month = {2005}, pages = {156404/1-4}, chapter = {156404}, keywords = {Sans titre}, author = {D. S{\'e}n{\'e}chal and P.-L. Lavertu and M.-A. Marois and A.-M. S. Tremblay} } @article {Senechal:2004ol, title = {Hot spots and pseudogaps for hole- and electron-doped high-temperature superconductors}, journal = {Physical Review Letters}, volume = {92}, number = {12}, year = {2004}, month = {2004}, pages = {126401/1-4}, abstract = {Using cluster perturbation theory, it is shown that the spectral weight and pseudogap observed at the Fermi energy in recent angle resolved photoemission spectroscopy of both electron- and hole-doped high-temperature superconductors find their natural explanation within the t-t(\&$\#$39;)-t(\&$\#$39;\&$\#$39;)-U Hubbard model in two dimensions. The value of the interaction U needed to explain the experiments for electron-doped systems at optimal doping is in the weak to intermediate coupling regime where the t-J model is inappropriate. At strong coupling, short-range correlations suffice to create a pseudogap, but at weak-coupling long correlation lengths associated with the antiferromagnetic wave vector are necessary.

}, author = {D. S{\'e}n{\'e}chal and A.-M. S. Tremblay} } @proceedings {7568, title = {Strong- and weak-coupling mechanisms for pseudogap in electron-doped cuprates}, volume = {Journal of Physics and Chemistry of Solids : 67}, year = {2004}, month = {2006}, pages = {189-192}, author = {Hankevych, Vasyl and Kyung, Bumsoo and Dar{\'e}, A.-M. and D. S{\'e}n{\'e}chal and A.-M. S. Tremblay} } @inbook {Allen:2004zn, title = {Theoretical Methods For Strongly Correlated Electrons}, year = {2004}, pages = {341{\textendash}355}, publisher = {Springer}, organization = {Springer}, chapter = {Conserving approximations vs. two-particle self-consistent approach}, abstract = {The conserving approximation scheme to many-body problems was developed by Kadanoff and Baym using the functional-derivative approach. Another approach for the Hubbard model also satisfies conservation laws, but in addition it satisfies the Pauli principle and a number of sum rules. A concise formal derivation of that approach, using functional derivatives, is given in this conference paper to highlight formal analogies and differences with conserving approximations.

}, author = {S. Allen and A.-M. S. Tremblay and Vilk, Y.M.}, editor = {D. S{\'e}n{\'e}chal and A.-M. S. Tremblay and C Bourbonnais} } @conference {Senechal:2003, title = {A cluster method for spectral properties of correlated electrons}, booktitle = {High Performance Computing Systems and Applications and OSCAR symposium}, year = {2003}, publisher = {NRC Press, Ottawa}, organization = {NRC Press, Ottawa}, keywords = {Sans titre}, author = {D. S{\'e}n{\'e}chal}, editor = {D. S{\'e}n{\'e}chal} } @book {7565, title = {Theoretical Methods for Strongly Correlated Electrons}, series = {CRM Series in Mathematical Physics}, volume = {Springer}, year = {2003}, pages = {361}, publisher = {2003}, organization = {2003}, address = {New York}, author = {D. S{\'e}n{\'e}chal and A.-M. S. Tremblay and C Bourbonnais} } @proceedings {7567, title = {What is the Hamiltonian for parent high-temperature superconductors?}, volume = {Proceedings of the 17th annual international symposium on High Performance Computing Systems and Applications and the OSCAR Symp}, year = {2003}, month = {2003}, pages = {71-77}, publisher = {NRC-CNRC Research Press, Ottawa}, author = {Alexis Gagn{\'e}-Lebrun and A.-M. S. Tremblay}, editor = {D. S{\'e}n{\'e}chal} } @article {Senechal:2002, title = {Cluster Perturbation Theory for {Hubbard} models}, journal = {Physical Review B}, volume = {66}, year = {2002}, pages = {075129}, keywords = {Sans titre}, author = {D. S{\'e}n{\'e}chal and D. Perez and D. Plouffe} } @inbook {7564, title = {Conserving approximations vs Two-Particle Self-Consistent Approach}, booktitle = {Theoretical Methods for Strongly Correlated Electrons}, series = {CRM Series in Mathematical Physics}, volume = {CRM Series in Mathematical Physics}, year = {2001}, pages = {341-355}, publisher = {2003}, organization = {2003}, chapter = {8}, author = {S. Allen and A.-M. S. Tremblay and Vilk, Y.M.}, editor = {D. S{\'e}n{\'e}chal and A.-M. S. Tremblay and C Bourbonnais} } @conference {Senechal:2000fv, title = {Les math{\'e}matiques et la physique du {XX}{\`e}me si{\`e}cle : quelques aspects}, booktitle = {Actes du 42e congr{\`e}s de l{\textquoteright}Association math{\'e}matique du Qu{\'e}bec}, year = {2000}, pages = {179{\textendash}193}, publisher = {{\'E}ditions Le Griffon d{\textquoteright}argile}, organization = {{\'E}ditions Le Griffon d{\textquoteright}argile}, address = {Sainte-Foy, Qu{\'e}bec}, keywords = {Sans titre}, author = {D. S{\'e}n{\'e}chal} } @article {Senechal:2000, title = {Spectral Weight of the {Hubbard} Model through Cluster Perturbation Theory}, journal = {Physical Review Letters}, volume = {84}, year = {2000}, pages = {522-525}, keywords = {Sans titre}, author = {D. S{\'e}n{\'e}chal and D. Perez and M Pioro-Ladri{\`e}re} } @article {Allen:2000lh, title = {The spin-1 ladder : A bosonization study}, journal = {Physical Review B}, volume = {61}, year = {2000}, pages = {12134{\textendash}12142}, keywords = {Sans titre}, author = {D. Allen and D. S{\'e}n{\'e}chal} } @article {A.-M.-S.-Tremblay:2000kh, title = {Strong correlations in low dimensional conductors: What are they and where are the challenges?}, journal = {Physics in Canada/La physique au Canada}, year = {2000}, month = {Sept./Oct.}, pages = {229}, keywords = {Sans titre}, author = {A.-M. S. Tremblay and C Bourbonnais and D. S{\'e}n{\'e}chal} } @article {Pairault:2000qe, title = {Strong-coupling perturbation theory of the Hubbard model}, journal = {European Physical Journal B}, volume = {16}, number = {1}, year = {2000}, pages = {85{\textendash}105}, abstract = {The strong-coupling perturbation theory of the Hubbard model is presented and carried out tu order (t/U)(5) for the one-particle Green function In arbitrary dimension. The spectral weight A(k,omega) is expressed as a Jacobi continued fraction and compared with new Monte-Carlo data of the one-dimensional, half-filled Hubbard model. Different regimes (insulator, conductor and short-range antiferromagnet) are identified in the temperature-hopping integral (T, t) plane. This work completes a first paper on the subject (Phys. Rev. Lett. 80, 5389 (1998)) by providing details on diagrammatic rules and higher-order results. In addition, the non half-filled case, infinite resummations of diagrams and the double occupancy are discussed. Various tests: of the method are also presented.

}, keywords = {Sans titre}, author = {Pairault, S. and D. S{\'e}n{\'e}chal and A.-M. S. Tremblay} } @article {Chitov:1998pi, title = {The {Fermi} liquid as a Renormalization-Group fixed point: the role of interference in the {Landau} channel}, journal = {Physical Review B}, volume = {57}, year = {1998}, pages = {1444{\textendash}1456}, keywords = {Sans titre}, author = {Chitov, G.Y. and D. S{\'e}n{\'e}chal} } @article {Shelton:1998ff, title = {SO(5)-Symmetric description of the low-energy sector of a ladder system}, journal = {Physical Review B}, volume = {58}, year = {1998}, pages = {6818{\textendash}6830}, keywords = {Sans titre}, author = {D.G. Shelton and D. S{\'e}n{\'e}chal} } @article {Pairault:1998jv, title = {Strong-coupling expansion for the Hubbard model}, journal = {Physical Review Letters}, volume = {80}, number = {24}, year = {1998}, pages = {5389{\textendash}5392}, abstract = {A strong-coupling expansion for models of correlated electrons in any dimension is presented. The method is applied to the Hubbard model in d dimensions and compared with numerical results in d = 1. Third order expansion of the Green\&$\#$39;s function suffices to exhibit both the Mott metal-insulator transition and a low-temperature regime where antiferromagnetic correlations are strong. It is predicted that some of the weak photoemission signals observed in one-dimensional systems such as SrCuO2 should become stronger as temperature increases away from the spin-charge separated state.

}, author = {Pairault, S. and D. S{\'e}n{\'e}chal and A.-M. S. Tremblay} } @article {Lamoureux:1998wj, title = {Thermal phase diagrams of columnar liquid crystals}, journal = {Phys. Rev. E}, volume = {58}, year = {1998}, pages = {5898{\textendash}5908}, keywords = {Sans titre}, author = {G. Lamoureux and Caill{\'e}, A. and D. S{\'e}n{\'e}chal} } @book {CFT:1997, title = {Conformal Field Theory}, year = {1997}, publisher = {Springer}, organization = {Springer}, keywords = {Sans titre}, author = {Di Francesco, P. and P. Mathieu and D. S{\'e}n{\'e}chal} } @article {Allen:1997mi, title = {Non-Abelian bosonization of the frustrated antiferromagnetic spin-1/2 chain}, journal = {Physical Review B}, volume = {55}, year = {1997}, pages = {299{\textendash}308}, keywords = {Sans titre}, author = {D. Allen and D. S{\'e}n{\'e}chal} } @article {Chitov:1995kl, title = {Renormalization-group study of interacting electrons}, journal = {Physical Review B}, volume = {52}, year = {1995}, pages = {13487{\textendash}13496}, keywords = {Sans titre}, author = {Chitov, G.Y. and D. S{\'e}n{\'e}chal} } @article {Senechal:1995qa, title = {Semiclassical description of spin ladders}, journal = {Physical Review B}, volume = {52}, year = {1995}, pages = {15319{\textendash}15326}, keywords = {Sans titre}, author = {D. S{\'e}n{\'e}chal} } @article {Allen:1995fu, title = {Semiclassical description of the frustrated antiferromagnetic chain}, journal = {Physical Review B}, volume = {51}, year = {1995}, pages = {6394{\textendash}6401}, keywords = {Sans titre}, author = {D. Allen and D. S{\'e}n{\'e}chal} } @article {Trudeau:1995jo, title = {Temperature dependence of the {ESR} spectrum of {$\rm CsNiCl_3$}}, journal = {Physical Review B}, volume = {51}, year = {1995}, pages = {334{\textendash}341}, keywords = {Sans titre}, author = {Y. Trudeau and D. S{\'e}n{\'e}chal and Poirier, M.} } @article {A.N.-Kirillov:1993lr, title = {Can fusion coefficients be calculated from the depth rule?}, journal = {Nucl. Phys. B}, volume = {391}, number = {651{\textendash}674}, year = {1993}, keywords = {Sans titre}, author = {A.N. Kirillov and P. Mathieu and D. S{\'e}n{\'e}chal and M. Walton} } @article {Senechal:1993dz, title = {Haldane gap in the quasi-one-dimensional nonlinear $\sigma$ model}, journal = {Physical Review B}, volume = {48}, year = {1993}, pages = {15880{\textendash}15885}, keywords = {Sans titre}, author = {D. S{\'e}n{\'e}chal} } @article {Senechal:1993ix, title = {The mass gap of the nonlinear $\sigma$ model through the finite temperature effective action}, journal = {Physical Review B}, volume = {47}, year = {1993}, pages = {8353{\textendash}8356 (Rapid. Comm.)}, keywords = {Sans titre}, author = {D. S{\'e}n{\'e}chal} } @article {Senechal:1992ao, title = {Chern-Simons superconductivity without parity violation}, journal = {Physics Letters B}, volume = {297}, year = {1992}, pages = {138-143}, author = {D. S{\'e}n{\'e}chal} } @conference {Senechal:1992wj, title = {Chern-Simons superconductivity without parity violation}, booktitle = {Proceedings of the 1992 CAP/NSERC workshop on integrable models, statistical models and quantum group, Kingston (Ontario)}, year = {1992}, publisher = {World Scientific}, organization = {World Scientific}, author = {D. S{\'e}n{\'e}chal} } @article {P.-Mathieu:1992zp, title = {Field identification in nonunitary diagonal cosets}, journal = {Int. J. Mod. Phys. A}, volume = {7 Suppl. 1B}, year = {1992}, pages = {731{\textendash}764}, keywords = {Sans titre}, author = {P. Mathieu and D. S{\'e}n{\'e}chal and M. Walton} } @article {P.-Di-Francesco:1992ud, title = {Integrability of the quantum {KdV} equation at $c= -2$}, journal = {Modern Physics Letters A}, volume = {7}, year = {1992}, pages = {701{\textendash}707}, keywords = {Sans titre}, author = {Di Francesco, P. and P. Mathieu and D. S{\'e}n{\'e}chal} } @article {Senechal:1991vl, title = {Chaos in the {Hermitian} one-matrix model}, journal = {Int. J. Mod. Phys. A}, volume = {7}, year = {1991}, pages = {1491{\textendash}1506}, keywords = {Sans titre}, author = {D. S{\'e}n{\'e}chal} } @article {Senechal:1991jt, title = {Gravit{\'e} quantique et mod{\`e}les de matrices}, journal = {Can. J. Phys.}, volume = {69}, year = {1991}, pages = {837{\textendash}854}, keywords = {Sans titre}, author = {D. S{\'e}n{\'e}chal} } @conference {Mathieu:1991ng, title = {KdV-type equations in subcritical strings}, booktitle = {Nonlinear fields: classical, random, semi-classical, Proceedings of the 27th Karpacz winter school of Theoretical Physics}, year = {1991}, author = {P. Mathieu and D. S{\'e}n{\'e}chal}, editor = {P. Garbaczewski et Z. Popowicz} } @article {Mathieu:1991cs, title = {Tachyonic Hermitian one-matrix models}, journal = {Modern Physics Letters A}, volume = {6}, year = {1991}, pages = {819{\textendash}829}, keywords = {Sans titre}, author = {P. Mathieu and D. S{\'e}n{\'e}chal} } @article {Mathieu:1991sf, title = {A well-defined multicritical series in the {Hermitian} one-matrix model}, journal = {Physics Letters B}, volume = {267}, year = {1991}, pages = {475{\textendash}480}, keywords = {Sans titre}, author = {P. Mathieu and D. S{\'e}n{\'e}chal} } @article {Hlousek:1990si, title = {Induced {Hopf} term in the nonlinear $\sigma$ model}, journal = {Phys. Rev. D}, volume = {41}, year = {1990}, pages = {3773{\textendash}3784}, keywords = {Sans titre}, author = {Z. Hlousek and D. S{\'e}n{\'e}chal and S.-H. Tye} } @article {Senechal:1989gd, title = {Search for four-dimensional string models}, journal = {Phys. Rev. D}, volume = {39}, year = {1989}, pages = {3717{\textendash}3730}, keywords = {Sans titre}, author = {D. S{\'e}n{\'e}chal} } @conference {Kawai:1987qm, title = {Construction of four-dimensional string models}, booktitle = {Proceedings of the APS Meeting at Salt Lake City}, year = {1987}, publisher = {World Scientific}, organization = {World Scientific}, author = {Hikaru Kawai and David C. Lewellen and Joel A. Schwartz and D. S{\'e}n{\'e}chal and S.-H. Henry Tye}, editor = {Carleton DeTar and James Ball} }