Technicolor in Light of LHC Data

Chivukula, R. Sekhar (Michigan State University)

Abstract:

In this talk I will review the constraints on technicolor and related theories in light of recent LHC data.

LHC: Higgs, less Higgs or more Higgs?

Ellis, Jonathan (King's College London and CERN)

Abstract:

After almost 48 years, the LHC may soon tell us whether something resembling the Higgs boson really exists. This talk will discuss the various possibilities, including composite models, an elementary Higgs boson and theories with multiple Higgs bosons such as supersymmetry, and review their experimental signatures.

The USQCD BSM Project

Fleming, George (Yale University)

Abstract:

The USQCD Beyond the Standard Model (BSM) project provides access to the U.S. DOE's Leadership Class computing resources for the study of BSM physics using lattice field theory methods. I will describe our current effort to generate SU(3) eight flavor configurations using the BlueGene/P at Argonne National Laboratory (ANL).

Accelerating universe and the conformal transformation in the scalar-tensor theory of gravity

Fujii, Yasunori (Advanced Research Institute for Science and Engineering, Waseda University)

Abstract:

Choosing conformal frames plays a basic role in understanding the accelerating universe, with the Jordan and Einstein frames identified with the theoretical and observational frames, respectively. The latter is selected, in particular, because of the mass of microscopic particles providing with the time unit by which the way of the cosmological expansion is measured, eventually resulting in $\Lambda\sim t^{-2}$ without appealing to a fine-tuning.

A very light dilaton

Grinstein, Benjamin (University of California, San Diego)

Abstract:

We present a completely perturbative model that displays behavior similar to that of walking technicolor. In one phase of the model RG-trajectories run towards an IR-fixed point but approximate scale invariance is spontaneously broken before reaching the fixed point. The trajectories then run away from it and a light dilaton appears in the spectrum. The mass of the dilaton is controlled by the "distance" of the theory to the critical surface, and can be adjusted to be arbitrarily small without turning off the interactions. There is a second phase with no spontaneous symmetry breaking and hence no dilaton, and in which RG trajectories do terminate at the IR-fixed point.

The phase diagram and fixed point structure of SU(3) gauge with 8 and 12 flavors of fermions

Hasenfratz, Anna (University of Colorado, Boulder)

Abstract:

In this talk I review our recent results on the phase structure and fixed point structure of SU(3) gauge model with 8 and 12 fundamental flavors. Our approach is two-fold. We investigate the renormalization group flow lines using MCRG methods in the weak coupling and the phase structure using zero and finite temperature simulations at stronger gauge couplings. The former approach shows an IRFP with 12 flavors but inconclusive with 8 flavors. The latter approach reveals a novel phase that is confining yet shows chiral symmetry restoration both with 12 and 8 flavors, bounded by bulk phase transitions at least in the 12 flavor case. I will discuss the properties and possible interpretation of this new phase.

Techni-Dilaton as a dark matter

Hong, Deog-Ki (Pusan National University)

Abstract:

We propose a new dark matter candidate, light decoupled techni-dilaton, which arises from the almost scale-invariant/conformal (walking) technicolor. We investigate its characteristic nature and discuss several cosmological and astrophysical constraints. It turns out that techni-dilatons are extremely weakly interacting and produced dominantly by the non-thermal mechanism to be the main component of dark matter with mass range between around 0.01 eV and 500 eV for typical walking technicolor scenarios.

Exploring the phases of $N_f=8$ and $12$ QCD on the lattice

Jin, Xiao-Yong (RIKEN, Advanced Institute for Computational Science)

Abstract:

There have been both theoretical and phenomenological interests in
non-abelian gauge theories with many fermion flavors. The possible
existence of an infrared fixed point in such theories suggests a rich
phase structure in the corresponding lattice theories. SU(3) gauge
theories with 8 and 12 flavors of degenerate fermions in the
fundamental representation have been argued to be near or in the
conformal phase. I present extensive simulations of the theories on
the lattice with 8 and 12 quark flavors, at both zero and finite
temperatures. Various hadronic variables, such as meson masses, pion
decay constant and quark potential, have been measured. We found a
cross-over with 8 flavors, and a first order bulk transition at small
quark masses with 12 flavors. At large quark masses with 12 flavors,
it becomes a quick cross-over. I will discuss a preliminary
investigation near the resultant second order critical point. Despite
the lattice artifact critical point, all the observables we have
measured on both sides of the transition/cross-over suggest high
similarities in the lattice theories between 8 and 12 flavors.

Higgs mechanism as a magnetic picture of dynamical symmetry breaking

Kitano, Ryuichiro (Tohoku University)

Abstract:

The electroweak symmetry breaking is perfectly consistent with the Higgs mechanism. But probably, the Higgs mechanism is just an effective description of some dynamics. I consider what is behind the Higgs mechanism.

Electroweak symmetry breaking and cold dark matter from strongly interacting hidden sector

Ko, Pyungwon (Korea Institute for Advanced Study)

Abstract:

We consider a hidden sector with new vectorlike confining gauge theories like QCD. Then a scale $\Lambda_H$ would be generated in the hidden sector by dimensional transmutation, and chiral symmetry breaking occurs in the hidden sector. Then this scale $\Lambda_H$ can play a role of the SM Higgs mass parameter, triggering electroweak symmetry breaking (EWSB). Thus all the mass scales of the SM sector can arise from the hidden sector. Furthermore the lightest hadrons in the hidden sector is stable by the flavor conservation of the hidden sector strong interaction, and could be the cold dark matter (CDM). We study collider phenomenology, and relic density and direct detection rates of the CDM of this model.

Study of the conformal hyperscaling relation through the Schwinger-Dyson equation

Kurachi, Masafumi (KMI, Nagoya University)

Abstract:

We study corrections to the conformal hyperscaling relation in the conformal window of the large Nf QCD by using the ladder Schwinger-Dyson (SD) equation as a concrete dynamical model. From the analytical expression of the solution of the ladder SD equation, we identify the form of the leading mass correction to the hyperscaling relation. We find that the anomalous dimension, when identified through the hyperscaling relation neglecting these corrections, yields a value substantially lower than the one at the fixed point \gamma_m^* for large mass region. We further study finite-volume effects on the hyperscaling relation, based on the ladder SD equation in a finite space-time with the periodic boundary condition. We find that the finite-volume corrections on the hyperscaling relation are negligible compared with the mass correction. The anomalous dimension, when identified through the finite-size hyperscaling relation neglecting the mass corrections as is often done in the lattice analyses, yields almost the same value as that in the case of the infinite space-time neglecting the mass correction, i.e., a substantially lower value than \gamma_m^* for large mass. We also apply the finite-volume SD equation to the chiral-symmetry-breaking phase and find that when the theory is close to the critical point such that the dynamically generated mass is much smaller than the explicit breaking mass, the finite-size hyperscaling relation is still operative. We also suggest a concrete form of the modification of the finite-size hyperscaling relation by including the mass correction, which may be useful to analyze the lattice data.

Holographic Walking Technicolor

Kutasov, David (University of Chicago)

Abstract:

We use holography to study Conformal Phase Transitions, which are realized in gauge theories coupled to defect fermions and are believed to play a role in four dimensional QCD and walking technicolor models of electroweak symmetry breaking. At strong coupling they can be modeled by the non-linear dynamics of a tachyonic scalar field with mass close to the Breitenlohner-Freedman bound in anti de Sitter spacetime. Taking the action for this field to have a Tachyon-Dirac-Born-Infeld form gives rise to models that resemble hard and soft wall AdS/QCD, with a dynamically generated wall. We explore some properties of the resulting models, particularly the spectrum of excitations and thermodynamics.

Lattice search for the composite Higgs mechanism close to the conformal window.

Kuti, Julius (University of California, San Diego)

Abstract:

I will present new results for two candidate models of the composite Higgs mechanism at the low end of the conformal window. The model with two fermions in the sextet representation of the SU(3) color gauge group does not show conformal behavior when the critical surface is approached in our simulations. Based on lattice systematics, the alternative interpretation of nearly conformal chiral symmetry breaking with composite Higgs mechanism will be discussed. Using conformal finite size scaling analysis, similar new results will be presented for the model with twelve massless fermions in the fundamental representation of the SU(3) color gauge group.

Phase structure of the Higgs-Yukawa model in the strong-coupling regime

Lin, C.-J. David (National Chiao-Tung University)

Abstract:

We present a lattice study of the phase structure of the Higgs-Yukawa model. In particular, we concentrate on the strong-coupling regime.

Techni-dilaton at LHC

Matsuzaki, Shinya (Maskawa Institute for Science and Culture, Kyoto Sangyo University)

Abstract:

I will talk about techni-dilaton sinatures
at LHC, in comparison with the current experimental data,
based on the susequent two papers recently written.

Dynamics in QCD like theories with infrared fixed point

Miransky, Vladimir (Western University)

Abstract:

I review the properties of the dynamics in QCD like theories with an infrared fixed point.

Thermodynamic study for (pre-) conformal dynamics in many flavor QCD

Miura, Kohtaroh (Laboratori Nazionali di Frascati, INFN)

Abstract:

Emergence of a conformal symmetry and a pre-conformal (walking) dynamics near the IR-fixed point in strongly flavored non-Abelian gauge theories has received much attention as a basis for strongly interacting mechanisms of electroweak symmetry breaking. Lattice Monte-Carlo simulations are now expected to provide a solid theoretical base to understand the (pre-) conformal nature.
After a brief review of and analytic studies for the IR-fixed point, we present a "thermodynamic" lattice study
for the (pre-) conformal dynamics based on our recent works. A loss of chiral phase transitions at finite temperature with increasing Nf (num. of flavors) indicates the emergence of a conformal phase. By using functional renormalization results
as a guide, we estimate the lower bound of the conformal window, and discuss the pre-conformal dynamics with a universal exponent for the critical temperature.

Lattice QCD with 4 and 8 flavors as exploration for the walking behavior

Nagai, Kei-ichi (KMI, Nagoya University)

Abstract:

We present the report of the LatKMI collaboration on the lattice QCD simulation for the cases of 4 and 8 flavors, the latter being expected to be a candidate for the walking technicolor having an approximate scale invariance near the infrared fixed point. The simulation was carried out based on the highly improved staggered quark (HISQ) action. We report preliminary results on the spectrum, analyzed through the chiral perturbation theory and the finite-size hyperscaling.

The low-energy spectra of 12 and 16 flavored QCD on the lattice

Ohki, Hiroshi (KMI, Nagoya University)

Abstract:

Information of the phase structure of many-flavor SU(3) gauge theory is of great interest,
since the gauge theories with the walking behavior
near the infrared fixed point are candidates of new physics
for the origin of the dynamical electroweak symmetry breaking.
We discuss the phase structure of the SU(3) gauge theory non-perturbatively
with lattice simulation varying the numbers of fundamental fermions.
We analyze the low energy hadron spectra based on chiral perturbation theory
as well as the finite size hyperscaling.

Study of conformal fixed point in many flavor QCD on the lattice

Onogi, Tetsuya (Osaka University)

Abstract:

We present our study on the conformal behavior of 12-flavor SU(3) and 8-flavor SU(2) gauge theory in fundamental representation using lattice gauge theory. Using step-scaling of the running coupling and renormalization schemes free from O(a) error, we find the existence of a conformal fixed point.
We also study the mass anomalous dimension for the IR fixed point.

Signatures of the conformal window

Pallante, Elisabetta (University of Groningen)

Abstract:

This talk reviews some recent work we have done, on the lattice and in the continuum, to establish the existence of a conformal window in SU(N) gauge theories and collect its most salient features. After reviewing strategy and aims of our lattice study, I will discuss to some extent the role of bulk phase transitions, the fate of the U(1) axial symmetry and the spectrum of SU(3) lattice gauge theories with fundamental fermions inside the conformal window. Moving to the continuum, I will discuss some AdS/CFT attempts to understand the underlying mechanism for the disappearance of the conformal window, and I will bridge them to lattice findings.

Conformal window and MWT on the Lattice

Pica, Claudio (University of Southern Denmark, CP3-Origins)

Abstract:

Some recent developments on the phase diagram of strongly interacting theories will be presented, regarding the existence of IR and UV fixed points as a function of the number and representation of fermionic matter fields.
As a concrete example of theory lying within the conformal window, I will show results from our recent Lattice study of Minimal Walking Technicolor (MWT), i.e. an SU(2) gauge theory with 2 Dirac adjoint fermions.

Phases of Gauge Theories

Ryttov, Thomas (Harvard University)

Abstract:

(TBA)

Conformal Dynamics and the Dilaton

Sannino, Francesco (CP3-Origins and Danish Institute for Advanced Study)

Abstract:

I will review the state-of-the-art of four-dimensional (near) conformal dynamics and its applications to Higgs physics and cosmology. An interesting possibility is that near conformal dynamics might feature a light dilaton. I will therefore describe the properties of the dilaton stemming from calculable models of near conformal dynamics as well as non-perturbative ones.

Solving non-perturbative renormalization group equation without field operator expansion and its application to the dynamical chiral symmetry breaking

Sato, Daisuke (Kanazawa University)

Abstract:

Non-perturbative renormalization group approach to the dynamical chiral symmetry breaking is an effective method which can accomodate beyond the mean field (ladder) approximation.
However usual method relys on the exansion of the equation with respect to the field operators, and due to this expansion.
It suffers divergences at the phase transtion point or vanishing bare mass limit. Here we solve the renormalization group equation directly as a partial differential equation and calculate the dynamical mass and the chiral condensates.
We formulate beyond the ladder equation and
the gauge independence of the results is improved.

Lattice Strong Dynamics for the LHC

Schaich, David (University of Colorado)

Abstract:

To explore the range of possible phenomena in strongly-coupled gauge theories, the Lattice Strong Dynamics (LSD) Collaboration is performing large-scale lattice studies of the flavor dependence of SU(3) gauge theories. Using lattice QCD as a baseline, we search for trends by systematically increasing the number of fundamental flavors towards the onset of IR conformality. I will review our recent progress measuring observables such as the electroweak S parameter and WW scattering in the six-flavor system, as well as exploring the potential IR-conformality of SU(3) gauge theory with ten flavors.

Recent Results on Technicolor and Extended Technicolor

Shrock, Robert (C. N. Yang Institute for Theoretical Physics, Stony Brook University)

Abstract:

We discuss some recent results on technicolor and extended technicolor models. These include studies with T. Ryttov of higher-loop corrections to the evolution from UV to IR of SU(N) gauge theories with various fermion contents relevant to walking TC. We have extended these analyses to supersymmetric theories and have compared the perturbative with exact results for the boundary of the IR-conformal phase. We also report some results on TC/ETC models with color-singlet technifermions.

Strong Top Dynamics in Light of LHC Data

Simmons, Elizabeth (Michigan State University)

Abstract:

This talk examines the implications of current LHC data for electroweak symmetry breaking models that include new strong top-quark dynamics.

Non-perturbative beta functions and conformality lost in gauge theories

Terao, Haruhiko (Nara Women's University)

Abstract:

We consider the non-perturbative beta functions of the SU(N) gauge theories by using the Wilson Renormalization group equations obtained in a simple approximation scheme. Then it is found that the beta function possesses a UV fixed point in addition to an IR fixed point in the conformal window and these fixed points merge and disappear at the boundary of the window. The anomalous dimensions of the SU(3) and the SU(2) gauge theories evaluated in this method will be also reported.

Wilson Many flavor QCD

Yamada, Norikazu (KEK)

Abstract:

We present our recent results on conformal window search using Wilson fermions. Talk will mainly focus on the update of the mass anomalous dimension of 10-flavor QCD. A preliminary result on the running coupling of SU(2) gauge theory with 6-flavor will be given. I would also like to mention our future plan.