Conveners
Theoretical developments and applications beyond Standard Model
- Hidenori Fukaya (The University of Osaka)
Theoretical developments and applications beyond Standard Model
- Fabian Zierler (Swansea University)
Theoretical developments and applications beyond Standard Model
- Dipankar Chakrabarti (IIT Kanpur)
Theoretical developments and applications beyond Standard Model
- Srimoyee Sen
Theoretical developments and applications beyond Standard Model
- Anosh Joseph (University of the Witwatersrand)
Theoretical developments and applications beyond Standard Model
- Biagio Lucini (Queen Mary University of London (UK))
Theoretical developments and applications beyond Standard Model
- Marcello Dalmonte (ICTP)
Theoretical developments and applications beyond Standard Model
- Navdeep Dhindsa
We focus on the fact that the Hamiltonian of the $1+1$D staggered fermion system can be smoothly deformed into that of Wilson fermions. We reinterpret the structure of the axial charge operator proposed by A. Chatterjee, S. D. Pace, and S.-H. Shao using Wilson fermions.
We show that the eigenstates of the axial charge operator can be interpreted as fermion states with a well-defined...
The symmetric mass generation (SMG) approach to the construction of lattice
chiral gauge theories attempts to use interactions to render mirror fermions
massive without symmetry breaking, to obtain the desired chiral massless
spectrum. If the zeros that often replace the mirror poles of fermion
two-point functions in an SMG phase are โkinematicalโ singularities, general...
We propose a way to formulate a realistic chiral gauge theory like the standard model on a lattice (or a general simplicial complex in curved spacetime), so that it has the correct continuum limit, with the correct symmetries and (co)homological properties, and no unwanted doublers or anomalies.ย Building on recent progress by Catterall and collaborators, our approach uses restricted...
This talk will be a follow up of Latham Boyleโs talk on discretizing a chiral gauge theory on the lattice. Building up on the natural geometrical discretization of Kahler-Dirac fermions with different polyforms fields (and the tetrad and spin-connection one forms), we will further see how this geometrical picture also suggests a novel formulation of Einstein gravity on the lattice. We will...
The type IIB matrix model has been proposed as a non-perturbative formulation of string theory. Its partition function is divergent due to the non-compactness of the Lorentz group. This has led to a new definition of the type IIB matrix model with the Lorentz symmetry fixed by the Faddeev-Popov procedure in a non-perturbative manner. We study this model using the complex Langevin method, and...
We perform non-perturbative lattice studies of pseudoscalar particle scattering states and of the vector resonance state in Sp(4) gauge theory coupled to two fundamental Dirac fermions. In the context of dark matter phenomenology, the corresponding continuum theory can provide a production mechanism for strongly interacting massive particles that serve as a candidate for dark matter. We...
The QCD axion is one of the most promising solutions to the strong CP problem, as it is also a viable dark matter candidate. Moreover, a large fraction of the current experimental searches focus on its coupling to photons. In this talk, we present the first determination of the QCD corrections to the model-independent part of the axionโphoton coupling from a first-principles lattice QCD...
We present new results from our lattice investigations of maximally supersymmetric Yang--Mills theory in three dimensions, focusing on its nonperturbative phase diagram. Using a lattice formulation that preserves part of the supersymmetry algebra at finite lattice spacing, we study the spatial deconfinement transition, which holography relates to the transition between localized and...
We study conserved charges for the 3+1 D staggered fermion Hamiltonian.
In addition to $\mathrm{U}(1)_V$ charge $Q_0$, we find that the system has three independent non-singlet charges $Q_{x_i}$ $(i=x,y,z)$ that generate axial $\mathrm{SU}(2)_A$ transformations in the continuum limit. On the lattice, these charges do not commute with $Q_0$, signaling a mixed anomaly between...
By employing K-theory to classify the Wilson Dirac operator on a lattice, we give a comprehensive formulation for various indices via its spectral flow. While the index of the overlap Dirac operator, which utilizes the Ginsparg-Wilson relation, is limited to flat tori in even dimensions, our formulation offers several key advantages: 1)It is straightforward to apply to the Atiyah-Patodi-Singer...
Topological invariants and their associated anomalies have played a crucial role in understanding low-energy phenomena in quantum field theories. In lattice gauge theory, the standard $\mathbb{Z}$-valued AtiyahโSinger index is formulated via the overlap Dirac operator through the GinspargโWilson relation, but extensions to more general topological invariants have remained limited. In this...
Minimally doubled fermions realize one pair of Dirac fermions on the lattice. Similarities to staggered fermions exist, namely, spin and taste degrees of freedom become intertwined, and a peculiar nonsinglet chiral symmetry and ultralocality are maintained. However, charge conjugation, some space-time reflection symmetries and isotropy are broken by the cutoff.
We address the most simple...
The deconfined quantum critical point (DQCP) exemplifies a phase transition beyond the Landau paradigm, yet its true nature remains debated. We investigate a candidate for the $SU(2)$ QCD$_3$ theory with $N$ fermions and a $Sp(N)/\mathbb{Z}_2$ global symmetry, which is a possible effective description of the DQCPโusing the recently proposed fuzzy sphere regularization. This method offers a...
The Thirring model in 2+1d with $N$ flavors can exhibit spontaneous
U(2$N)\to\,$U($N)\otimes$U($N$) breaking through fermion - antifermion condensation in the limit $m\to0$. With no small parameter in play the symmetry-breaking dynamics is strongly-interacting and quantitative work requires a fermion formulation accurately capturing global symmetries. We present simulation results for $N=1$...
Understanding thermalization in isolated non-Abelian gauge theories is a key challenge for quantum simulation. We present a study of the Eigenstate Thermalization Hypothesis (ETH) in 1+1-dimensional SU(2) lattice gauge theory with one flavor of dynamical staggered fermions. Using the gauge-invariant Loop-String-Hadron (LSH) framework, we perform exact diagonalization on finite lattices to...
Cuprate superconductors, the most commonly known class of high-$T_c$ superconductors, have much richer properties than the conventional superconductors, yet much of it is not well-understood. To explain their physical origin, many theories involving emergent gauge fields have been put forth in recent years. Focusing on the theory developed in Christos et al., PNAS 120(21) e2302701120 (2023), ...
We show that the tensor renormalization group offers a consistent framework in which twisted partition functions can be employed as order parameters to study critical phenomena. Investigating the two-dimensional Ising model and the three-dimensional $O(2)$ model as concrete examples, we demonstrate that critical points associated with spontaneous symmetry breaking can be located solely from...
We present the entanglement entropy for the two-dimensional real scalar ฯ^4 theory using a higher-order tensor renormalization group algorithm. This quantity is employed to identify a critical point of the system. We will also discuss the continuum limit of the critical point.
Tensor Renormalization Group (TRG) is a promising numerical
method for systems with the sign problem. However, the computational
cost increases exponentially with the dimension, which makes the
development of effective algorithms for three-dimensional or
four-dimensional models a crucial challenge. As a first step toward
addressing this, we study the three-dimensional finite-density...
We develop a computational scheme based on the tensor renormalization group method to investigate the multi-particle state of the (1+1)d Ising model. The scheme is started by representing the system as a tensor network and coarse-graining it with the higher-order tensor renormalization group algorithm. Thereafter, we construct the corresponding numerical transfer matrix from the coarse-grained...
We determine the role of topology from the eigenmodes, and extract the chiral condensate from the eigenvalue density of minimally doubled fermions (MDF), namely in Karsten-Wilczek (KW) and Borici-Creutz (BC) formulations. We employ MILC asqtad ensembles with $N_f=2+1$ dynamical flavors of quarks [1] as backgroud gauge fields. Using flavored mass terms [2,3], we find that the spectral flow of...
We present new results for Sp(4) Yang-Mills theory around its first-order thermal phase transition by reconstructing the density of states via the LLR algorithm. We show results on different space and time extents, as well as aspect ratios, and estimate discretization artifacts. We see clear signatures of the first-order transition and determine the critical coupling, the specific heat and set...
Methods based on analyticity, such as Nevanlinna-Pick interpolation, have the promise of providing rigorous constraints on real-time observables (e.g. spectral functions), assuming only causal consistency of the underlying euclidean data. In this talk, I will review recently discovered connections between Nevanlinna-Pick interpolation and moment problems, which provide a discrete euclidean...
The two-dimensional O(3) nonlinear sigma model is a well known toy model for studying non-perturbative phenomena in quantum field theory and QCD in particular. A central challenge is the renormalization of the energy-momentum tensor, which is complicated by nonlinear Ward identities constraining operator mixing and by large cutoff effects affecting the determination of renormalization...
We investigate the critical behaviour of a $\mathbb{Z}_2$-symmetric scalar field theory defined on Bethe lattices (the tree limit of regular hyperbolic tessellations) using both lattice perturbation theory and the non-perturbative functional renormalization group. Owing to the hyperbolic nature of such graphs, the Laplacian lacks a zero mode and exhibits a spectral gap, which is an external...
The loop-string-hadron (LSH) formulation for lattice gauge theories has been developed in the Hamiltonian framework for application in quantum simulation and tensor-network calculations. A major driver of its development has been eventual application to QCD. The LSH formalism for SU(2) gauge fields was quickly developed for coupling to staggered quarks, in 1D space, and in multidimensional...
Quantum Link Models with dynamical matter coupled to spin-1/2 U(1) gauge fields in d=2+1 and 3+1 can give rise to phases expected in QED and beyond. Using exact diagonalization techniques, we show that the ground state is always the sector which satisfies (G_e,G_o) = (d,-d), where d is the spatial dimension and e and o are even and odd sites. It can be analytically proven that this sector is...
We construct quantum Monte Carlo methods for simple qubit regularized gauge theories in various dimensions that do not suffer from sign problems. Results from these calculations suggest that these theories contain both confined and deconfined phases. Finite temperature phase transitions between these phases show the expected universality classes of traditional gauge theories in various...
We employ the wavelet formalism of quantum field theory to study field theories in the nonperturbative Hamiltonian framework. Specifically, we make use of Daubechies wavelets in momentum space. These basis elements are characterised by a resolution and a translation index that provides for a natural nonperturbative infrared and ultraviolet truncation of the quantum field theory. As an...
In a recent paper [1], we introduced a simplified Lattice Field Theory framework that allows experimental observations from major Brain-Computer Interfaces (BCI) to be interpreted in a simple and physically grounded way. From a neuroscience point of view, our method modifies the Maximum Entropy Model for Neural Networks so that also the time evolution of the system is taken into account, and...
We present Symplectic Quantization, a novel functional approach to quantum field theory that allows us to sample quantum fluctuations directly in Minkowski spaceโtime, bypassing the limitations of traditional importance sampling techniques restricted to imaginary time. Our method is based on a deterministic dynamics governed by Hamilton-like equations in an auxiliary time parameter $\tau$. We...
We introduce Symplectic Quantization, a functional approach to quantum field theory that samples quantum fluctuations directly in Minkowski spaceโtime, bypassing the traditional importance sampling techniques that are restricted to imaginary-time. Our method evolves fields via deterministic Hamilton-like equations in an auxiliary time parameter $\tau$. We prove that the microcanonical...
In this work, we explore a numerical approach to performing the inverse Laplace transformation, with an emphasis on stability and robustness under noisy conditions. Our quadrature-based method integrates reparameterization, data smoothing, optimization techniques, and various approaches to regularizing ill-conditioned systems. Together, these elements enable consistency checks that enhance the...
Recent software advances now allow large-scale lattice studies of the CorriganโRamond large-$N_c$ limit of Yang-Mills theory coupled with a two-index antisymmetric fermion, providing a path to SUSY Yang-Mills. We are currently generating ensembles for $N_c=4,5,6$ for lattice spacings in the range $0.1 - 0.08 \,\mathrm{fm}$, enabling a careful study of cutoff effects and lattice topological...
Simulating the real-time dynamics of non-Abelian lattice gauge theories in more than 1+1 dimensions presents a significant computational challenge. We present an exact diagonalization study of 2+1-dimensional SU(2) lattice gauge theory, leveraging the gauge-invariant Loop-String-Hadron (LSH) framework. By harnessing GPU-based computation, we have successfully pushed the classical simulation...
