Conveners
Particle Physics Beyond the Standard Model
- Daniel Nogradi (Eotvos University Budapest - Universidad Autonoma Madrid)
Particle Physics Beyond the Standard Model
- Oliver Witzel (Universität Siegen)
Particle Physics Beyond the Standard Model
- Georg Bergner (Friedrich-Schiller-Universität Jena, WWU Münster)
Particle Physics Beyond the Standard Model
- Anna Hasenfratz (university of colorado boulder)
The SU(3) gauge theory with $N_f=10$ fundamental flavors is thought to be close to the sill of the conformal window. I describe a recent study of this system using the continuous $\beta$ function method based on the gradient flow. We use a Pauli-Villars improved gauge action and several gradient flow transformations. These features allow us to study the system at much stronger gauge...
We use the continuous renormalization-group method, based on the gradient flow, to study a candidate theory of composite Higgs and a partially composite top. The model is an SU(4) gauge theory with four Dirac fermions in each of the fundamental and two-index antisymmetric representations. Our lattice action includes a set of Pauli-Villars fields, which decouple in the continuum limit while...
Symmetric mass generation (SMG) is a new mechanism that leads to massive bound states without spontaneous symmetry breaking. An SMG phase could lead to a resolution of the chiral fermion problem on the lattice. Expectations from 't Hooft anomaly cancellation, combined with recent finite-size scaling results, indicate that the SU(3) gauge-fermion system with two sets of staggered fermions could...
The renormalization group beta function describes the running of the renormalized coupling, connects the ultraviolet and infrared regimes of quantum field theories, and characterizes the nature of gauge-fermion systems. Using the concept of the continuous beta function and renormalized couplings obtained from the gradient flow, we present results for SU(3) gauge theories with $N_f=2$, 4, 6, 8,...
The origin of the infinite volume based beta-function from the gradient flow is discussed with its technical implementations. Recent applications include the new beta function with ten massless fermion flavors in the SU(3) color representation and the new effort to calculate with high precision the QCD running coupling at the $Z$~pole.
Speaker: Prof. Robert Shrock
Institution: Stony Brook University
Title: Higher-Order Calculations of Anomalous Dimensions at
Infrared Fixed Points in Gauge Theories and Studies of Renormalization-Group
Behavior of Some Scalar Field Theories
Abstract
We discuss higher-order calculations of anomalous dimensions of
operators at an infrared fixed point in asymptotically free...
Euclidean Dynamical Triangulation as a lattice approach to quantum gravity has produced results that are compatible with semiclassical gravity in four dimensions. We explore the cosmological application of EDT by studying the behavior of the vacuum energy on the lattice. Although the lattice gravity calculations are broadly consistent with an emergent four-dimensional de Sitter space...
Euclidean Dynamical Triangulation (EDT) is a lattice approach to quantum gravity that has produced results compatible with semiclassical gravity in four dimensions. Although the lattice gravity calculations are broadly consistent with an emergent four-dimensional de Sitter space geometry, the calculations give corrections to a purely constant cosmological constant term. These corrections are...
We present results from simulations of a spin(4) lattice gauge theory in four
dimensions containing a single flavor of massless reduced staggered fermion. This model does not
allow for single site gauge invariant bilinear fermion terms and instead
we show that it develops a four fermion condensate in the confining regime. The absence of symmetry breaking is consistent with the cancellation...
In this work we perform calculations in order to determine the renormalization factors and the mixing coefficients of the Yukawa and the quartic couplings in $\mathcal{N} = 1$ Supersymmetric QCD. The Yukawa couplings describe the interactions between gluino, quark and squark fields whereas the quartic couplings describe four-squark interactions. We discretize the action on a Euclidean lattice...
We present our lattice simulations of gauge theories coupled to fermions and scalar fields in adjoint and fundamental representation. Supersymmetric gauge theories emerge as specific limiting cases within this theory space. We discuss our efforts to tune the parameters towards the supersymmetric limit.
In this talk, I will focus on naturalness considerations in SM/2HDM augmented by a Triplet field, here dubbed as Higgs Triplet Models. I will show that the Veltman conditions in HTM are modified by virtue of the additional scalar charged states and that one loop quadratic divergencies can be driven to zero within the allowed respective parameter spaces, usually constrained by unitarity and...
We present an analysis of newly expanded and refined data from lattice studies of the SU(3) gauge theory with $N_f=8$ light Dirac fermions, a theory which lies close to the boundary of the conformal window. We first assume that this theory is just outside the conformal window and identify a light unflavored scalar meson in this case as an approximate dilaton. We show fits of the lattice data...
The mesonic $f_{PS} / m_V$ and $f_V / m_V$ ratios, with f the decay constant and m the meson mass, are calculated in mass perturbed conformal gauge theories to NNLO and N$^3$LO orders, respectively. Here NNLO and N$^3$LO refer to the non-relativistic effective theory expansion which is the applicable framework. The results are expanded a la Banks-Zaks in order to end up with scheme-independent...
The LSD collaboration is studying Stealth Dark Matter, an SU(4) gauge theory, whose ground state spin-0 baryon is the dark matter candidate. We are investigating Stealth Dark Matter with two fermions in the fundamental representation using the quenched approximation. I will discuss our baryon operator construction using LapH and lattice octahedral group irreps. Then I will present the latest...
Several SU(N) gauge theories have been explored as candidates for producing stable dark matter particles that can explain their relative abundance, while also evading current constraints from direct, indirect and collider searches. In this talk, I will present the confinement and spectral properties of a new model we name Hyper Stealth Dark Matter, which involves an SU(4) gauge theory with 1...
We are examining one-flavour $SU(N_c)$ gauge theories with one fermion in the antisymmetric representation as a candidate to approximate $\mathcal{N}=1 $ SYM due to their equivalence in the large-$N_c$ limit. Summarising results on spectral evaluations of $N_c=3$, we will report on the progress of dynamical calculations for $N_c > 3$. Here we will discuss cutoff effects and challenges in...
In this work we consider strongly interacting dark matter candidates which are composite states of $N_f=2$ fermions charged under a Sp(4) gauge group in the fundamental representation. We present first results from lattice calculations for the scattering properties of two pseudo-Goldstone bosons in the isospin I=2 channel. We report results for searches for bound states and resonances and...
First order phase transitions in the early universe might produce a detectable background of gravitational waves. As these phase transitions can be generated by new physical sectors, it is important to quantify these effects. Many non-Abelian pure Yang-Mills gauge theories are known to have first order deconfinement phase transitions, with properties that can be studied with lattice...
In the context of Composite Higgs Models, where the standard model Higgs is interpreted as a pseudo Nambu–Goldstone Boson, baryons formed by matter in different representations, known as chimera baryons, could serve as top partners. The chimera baryon sharing the same quantum number as the top quark can mix with it, effectively lifting the mass of the top quark through the see-saw mechanism....
Four-dimensional gauge theories based on symplectic Lie groups have been introduced as the microscopic origin for elegant proposals of several new physics models. Numerical studies pursued on the lattice can provide the quantitative information necessary for the application of such models.
To this purpose, we implemented $Sp(2N)$ gauge theories using Monte Carlo techniques within Grid, a...
Composite Higgs models are a class of models proposed to address the hierarchy and naturalness problems associated with the Standard Model fundamental scalar Higgs. $SU(2)$ with two fundamental flavours is a minimal model for the composite Higgs sector which is not yet ruled out by experimental data. We present lattice results for $SU(2)$ with two fundamental mass degenerate flavours. For the...
In this investigation we study the most general two Higgs doublet model with
SU(2) gauge fields on the lattice.
The phase space is probed through the computation of gauge-invariant global
observables serving as proxies for order parameters.
In each phase, the spectrum of the theory is analysed for different combinations
of bare couplings and different symmetry breaking patterns.
The...