Weak Renormalization Group Approach for Dynamical Chiral Symmetry Breaking

Aoki, Ken-Ichi (Kanazawa University)

Abstract:

We set up weak renormalization group equation for dynamical chiral symmetry breaking systems which allows us to work with only fermionic degrees of freedom. So far the fermionic system encounters the divergence at the critical scale of the dynamical chiral symmetry breaking. We define the weak partial differential equation representing the scale dependent change of effective fermionic interactions. The weak renormalization group equation can be solved without any ambiguity and the solution perfectly describes the physically correct singularity due to the phase transition even in case of the first order transition having the finite jump of the dynamical mass at the critical scale.

Spectral properties of Nf=8 SU(3) gauge theory

Aoki, Yasumichi (KMI,Nagoya)

Abstract:

QCD with 8 flavors of fundamental fermions has been investigated in
LatKMI collaboration. In the series of our studies, we first pointed
out the possibility of this theory having walking dynamics. Further,
the lowest flavor singlet scalar meson was found as light as pions
in the range of quark mass we investigated. In this talk we present
an update of the spectral properties of this theory.

Large-scale magnetic fields, non-Gaussianity, and gravitational waves from inflation

Bamba, Kazuharu (Leading Graduate School Promotion Center, Ochanomizu University)

Abstract:

We investigate the generation of large-scale magnetic fields in inflationary cosmology, particularly, in a kind of moduli inflation motivated by racetrack inflation in the context of the Type IIB string theory.
In this model, the conformal invariance of the hypercharge electromagnetic fields is broken due to the coupling of both the scalar and pseudoscalar fields to the hypercharge electromagnetic fields.
We first evaluate the following three cosmological observable quantities:
(i) The current magnetic field strength on the Hubble horizon scale, which is much smaller than the upper limit from the back reaction problem,
(ii) local non-Gaussianity of the curvature perturbations owing to the existence of the massive gauge fields, and
(iii) the tensor-to-scalar ratio.
We explicitly demonstrate that the resultant values of local non-Gaussianity and the tensor-to-scalar ratio are consistent with the Planck data.
Reference:
K. Bamba, arXiv:1411.4335 [astro-ph.CO],
accepted for publication in Physical Review D.

Recent results from SU(2) with one adjoint Dirac flavour

Bennett, Ed (Swansea University)

Abstract:

We present some results for SU(2) with one adjoint Dirac flavour from lattice studies. Data for the spectroscopy, the static potential, topological charge, and the anomalous dimension of the fermionic condensate are included. Our findings are found to be inconsistent with conventional confining behaviour, instead pointing tentatively towards a theory lying within or very near the onset of the conformal window, with an anomalous dimension of the fermionic condensate of almost 1. Implications of these findings on the building of models of strongly-interacting dynamics beyond the standard model are discussed.

The Jet Energy Profile as a BSM Analysis Tool at the LHC

Chivukula, R. Sekhar (Michigan State University)

Abstract:

The 14 TeV LHC will have unprecedented reach for the discovery of new particles decaying to dijets. We show that the study of the jet energy profiles of the two leading jets in the di-jet channel is a powerful discriminant between different kinds of BSM physics. Including statistical uncertainties in the signal and the QCD backgrounds, we show that one can distinguish, in a model-independent way, between gg, qg, and qqbar resonances; an evaluation of systematic uncertainties in the measurement of the jet energy profile will require a detailed detector study once sufficient 14 TeV di-jet data is in hand.

Walking dynamics from gauge-gravity duality

Elander, Daniel (Purdue University)

Abstract:

We will discuss solutions in Type IIB supergravity corresponding to either a system of wrapped D5-branes or a system of D3- and D5-branes. These can be thought of as arising as deformations of the Maldacena-Nunez or Klebanov-Strassler backgrounds. We will argue that the corresponding dual field theories exhibit walking dynamics. Computing the spectrum of scalar glueballs, we find a light state, the mass of which is suppressed by the length of the walking region, thus suggesting it is a dilaton.

Composite Dark Matter

Fleming, George (Yale University)

Abstract:

Although dark matter has only been observed gravitationally, it would be an amazing coincidence if it did not interact at all with standard model particles. We will discuss how to sequester electroweak-charged dark constituents in electroweak-neutral stable composites. We present a model of "Stealth Dark Matter" where dark composites couple to the electroweak sector only via polarizability, rendering them nearly impossible to detect in present experiments.

Top Mode pseudo Nambu-Goldstone Boson Higgs Model

Fukano, Hidenori (KMI, Nagoya University)

Abstract:

We discuss the Top Mode pseudo Nambu-Goldstone boson Higgs (TMpNGBH) model which has recently been proposed as a variant of the top quark condensate model in light of the 126 GeV Higgs boson discovered at the LHC. In this talk, we focus on the vacuum alignment and the phenomenologies of characteristic particles of the TMpNGBH model.

Approaching conformality with 4+8 flavors

Hasenfratz, Anna (University of Colorado Boulder)

Abstract:

We study the transition between spontaneous chiral symmetry breaking
and conformal behavior in the $SU(3)$ theory with multiple fermion
flavors. Instead of the traditional approach of changing the number of flavors, we keep the number of fermions fixed but lift the mass of a subset, keeping the remaining fermions near to the massless chiral limit. This way we can interpolate continuously between the conformal
and chirally broken dynamics. In particular, we consider four light and eight heavy flavors and investigate the running/walking gauge coupling
and the low energy meson spectrum, including the $0^{++}$ iso-singlet scalar state in this system.
Our preliminary data reveal an iso-singlet scalar that is considerably lighter than the pion at large fermion mass but becomes heavier at smaller masses. This behavior is of particular phenomenological interest.

Holographic Estimate of Isospin splitting in hadron mass

Hong, Deog-Ki (Pusan National University)

Abstract:

Recently the electromagnetic interaction and the current quark mass contribution to hadron mass have been accurately calculated in lattice QCD, giving values close to physical ones. In this talk we present the holographic calculations of both electromagnetic mass of hadrons and the current quark mass contributions to the hadron mass in Sakai-Sugimoto model of holographic QCD. Our holographic estimates are found to be consistent with recent lattice results.

Gauge symmetry and the functional renormalization group

Itoh, Katsumi (Niigata University)

Abstract:

The functional renormalization group (FRG) is a robust approach to
quantum field theory and has been successfully applied to various kind of problems. However the introduction of an momentum cutoff often
breaks symmetry present in the theory. The most important example is the gauge symmetry. We discuss how a symmetry survives in the presence of a cutoff and then apply our understanding to QED as the simplest case. A modified version of the Ward-Takahashi identity is solved partially to constrain the Wilson action. Furthermore, we study the flow equation for the action.

IR fixed points in SU(3) gauge Theories

Iwasaki, Yoichi (U. Tsukuba and KEK)

Abstract:

The main objective in the talk is to identify the location of the IR fixed point in the SU(3) gauge theories with $N_f$ fundamental fermions within the conformal window $N_f^c ¥le N_f ¥le 16$.
We propose a novel and simple RG method to specify the location and the anomalous mass dimension, and further the method to derive the propagator of a meson in the continuum limit on the IR fixed point.

Holography and the conformal window in the Veneziano limit

Jarvinen, Matti (Ecole Normale Superieure, Paris)

Abstract:

I will start with an introduction to holography for QCD in the Veneziano limit
(large N_f and N_c with fixed x=N_f/N_c). I will then discuss a specific class of string-inspired bottom-up models, named V-QCD, and overview results related to the conformal window and walking dynamics. In particular, I discuss the S-parameter, the technidilaton, and the mass dependence of meson states.

Gauge/gravity duality - From lattice gauge theory to black hole

Kadoh, Daisuke (KEK)

Abstract:

In this talk, we will talk about our recent work, a verification of gauge/gravity duality by lattice simulations. In particular, 1+0 dim SYM with 16 supercharges is expected to be dual to a black hole in
higher dimensions at low temperature in the large N limit. We aim to verify the duality conjecture by comparing lattice results in the gauge theory side with analytic expectations in the gravity side.

Strong coupling limit of lattice QCD with many staggered quarks

Kim, Seyong (Sejong University)

Abstract:

Using Monte Carlo simulation, we study the strong coupling limit of lattice QCD with many staggered quark flavors. After identifying an existence of chiral symmetric and color deconfined phase, we investigate the properties of this phase via meson spectrum, gluonic observable and Dirac eigenvalue spectrum for various lattice volume sizes and then speculate the phase diagram of QCD with many quark flavors.

Hidden Local Symmetry as magnetic gauge theory

Kitano, Ryuichiro (KEK)

Abstract:

Magnetic monopole versus vortex as gauge-invariant topological objects for quark confinement

Kondo, Kei-Ichi (Chiba University)

Abstract:

First, we give a gauge-independent definition of chromomagnetic monopoles in SU(N) Yang-Mills theory which is derived through a non-Abelian Stokes theorem for the Wilson loop operator. Then we discuss how such magnetic monopoles can give a nontrivial contribution to the Wilson loop operator for understanding the area law of the Wilson loop average.Next, we discuss how the magnetic monopole condensation picture are compatible with the vortex condensation picture as another promising scenario for quark confinement. We analyze the profile function of the magnetic flux tube as the non-Abelian vortex solution of U(N-1) gauge-Higgs model, which is to be compared with numerical simulations on a lattice for SU(N) Yang-Mills theory.This analysis gives an estimate of the string tension based on the vortex condensation picture, and possible interactions between two non-Abelian vortices. Moreover, if time permits, we discuss a quantum origin of the scale generation due to dimensional transmutation using the novel large N analysis for SU(N) Yang-Mills theory.

Toward the minimal realization of a light composite Higgs

Kuti, Julius (University of California, San Diego)

Abstract:

After reviewing the framework of working close to the conformal window in the SCGT paradigm, related lattice challenges are illustrated with a case study. It is based on a particularly interesting gauge theory with a fermion doublet in the two-index symmetric (sextet) representation of the SU(3) color gauge group. Recent results suggest that the model is very close to the conformal window and a light composite scalar, perhaps a Higgs impostor with or without dilaton-like interpretation, appears to emerge. The lightest baryon of the model on the 3 TeV scale has intriguing implications.

Lattice study of the Higgs-Yukawa model with a dimension-6 operator

Lin, David (National Chiao-Tung University, Taiwan)

Abstract:

We perform lattice investigation of the Higgs-Yukawa model with a dimension-6 operator as the prototype of physics beyond the standard model (BSM). By studying the Higgs boson mass, we can obtain bounds on the coupling for this BSM operator.

Higgs Mass in D-term triggered Dynamical SUSY Breaking

Maru, Nobuhito (Osaka City University)

Abstract:

We discuss a possibility that the electroweak symmetry dynamically broken in our previous proposed D-term triggered Dynamical SUSY Breaking (DDSB) scenario. We also study whether 126 GeV Higgs mass can be realized in DDSB framework. In this analysis, the top-stop contribution is taking into account in a Hartree-Fock approximation.

SU(2) lattice gauge theory with many flavors of domain-wall fermions

Matsufuru, Hideo (High Energy Accelerator Research Organization (KEK))

Abstract:

We numerically study the SU lattice gauge theory with many flavors.
Dynamical simulation is performed with the standard domain-wall
fermions in fundamental representation at numbers of flavors
Nf=2,4,6, and 8. Nf dependence of the static potential, meson
spectrum, and the eigenvalue spectrum of the Dirac operator
is investigated so as to determine the phase structure.

One-family walking technicolor in light of LHC-Run II

Matsuzaki, Shinya (Nagoya University)

Abstract:

The LHC Higgs with mass around 125 GeV can be identified as the technidilaton, pseudo Nambu-Goldstone boson for the spontaneous breaking of scale symmetry in the one-family model of walking technicolor (one-family walking technicolor). The coupling properties of the technidilaton in the one-family walking technicolor, with N_{TF}=8 and N_{TC}=4, are actually consistent with the currently reported LHC Higgs data, to be more precisely tested at the upcoming LHC-Run II, in comparison with the standard model Higgs. This talk will summarize the
current status on the technidilaton phenomenology in the LHC-Run I.
Besides the technidilaton, the one-family walking technicolor predicts
the rich particle spectrum such as technipions and technirho mesons.
This talk will also cover discussions on the LHC phenomenology of those technihadrons and the discovery channels, which would be smoking-guns of the one-family walking technicolor, to be accessible at the LHC-Run II.

Who is afraid of the Landau Pole?

Miransky, Vladimir (Western University)

Abstract:

I discuss the dynamics in the vector like gauge theories with a nontrivial infrared fixed point in the phase with the Landau pole.

Topological insights in many flavor QCD on the lattice

Nagai, Kei-ichi (KMI, Nagoya University)

Abstract:

LatKMI Collaboration discusses the topological insights
in many flavor QCD on the lattice.
We explore walking/conformal/confining phase
in Nf=0, 4, 8 and 12 (in particular Nf=8) lattice QCD
via the topological charge and susceptibility,
eigenvalues and anomalous dimension.

Scalar mesons in lattice QCD

Nonaka, Chiho (Nagoya University)

Abstract:

Recent experiments and precise and systematic analyses of the π-π scattering
respecting the crossing symmetry as well as the chiral symmetry have revealed
the existence of the low-mass scalar meson with a mass from 400 to 700 MeV.
Then the physical content and the mechanism for realizing such a low-lying state
in the JPC = 0++ state have prompted much debate.
Here I will show our recent progress for understanding of scalar mesons from
the point of view of lattice QCD study.

Lattice study of the scalar and baryon spectra in many flavor QCD

Ohki, Hiroshi (KMI, Nagoya University)

Abstract:

In the search for a composite Higgs boson in walking technicolor models, many flavor QCD, in particular with Nf=8, is an attractive candidate, and has been found to have a composite flavor-singlet scalar as light as the pion. Based on lattice simulations of this theory with the HISQ action, we will present our preliminary results on the scalar decay constant using the fermionic bilinear operator, and the mass of the baryon state which could be a candidate of the dark matter. Combining these two results, implications for the dark matter direct detection will be also discussed.

Around and across the endpoint of the conformal window

Pallante, Elisabetta (University of Groningen)

Abstract:

I discuss theoretical insights and lattice tools useful to establish how non-Abelian gauge theories evolve from a confining and chirally broken phase to a conformal phase.

Hidden local and mended symmetries and massive compact stars

Rho, Mannque (CEA Saclay)

Abstract:

The recent observation of ~ 2 solar-mass "neutron" stars necessitates a serious revamping of the current approaches to the equation of state of compact-star matter. The absence of a QCD lattice method at high density forces the theorists to resort to effective field theories. The potential role, in dense medium of massive stars, of the light-quark vector mesons as hidden local degrees of freedom and the scalar f_0(500) as Nambu-Goldstone boson of spontaneously broken scale symmetry will be described.

Investigation of the scalar spectrum in 8-flavor QCD

Rinaldi, Enrico (Lawrence Livermore National Laboratory)

Abstract:

I present the most recent results of the Lattice Strong Dynamics collaboration on the SU(3) 8-flavor theory. We measure the lightest pseudoscalar, scalar and vector masses using nHYP staggered fermions simulations on large volumes and at very small fermion masses. One of the most interesting features of this theory is a light flavor-singlet scalar state that is lighter than the vector resonance and at the scale of the pseudoscalar one. We comment on the existence of such state and the challenges of its analysis.

Rethinking Naturalness: The Interacting Ultraviolet Safe Behaviour of Gauge-Yukawa Theories

Sannino, Francesco (CP3-Origins, University of Southern Denmark)

Abstract:

I will critically introduce, classify and discuss the fundamental open issues related to either composite or elementary extensions of the standard model. As for the progress I will exhibit, among other things, the first proof of existence of nonsupersymmetric and non-asymptotically free 4D Gauge-Yukawa theories (structurally similar to the standard model) which are UV finite thanks to the existence of an exact interacting quantum UV fixed point in the gauge, Yukawa and scalar self-couplings. The quantum moduli space of the theory will also be precisely determined. Theories with this behaviour have been searched for on the lattice for the past several decades. Our results show the critical ingredients that are needed to construct new classes of fundamental theories featuring elementary scalars. I will then comment on the wide phenomenological impact of this discovery.

Maximally supersymmetric Yang--Mills on the lattice

Schaich, David (Syracuse University)

Abstract:

Practical lattice discretizations of supersymmetric gauge theories are notoriously difficult to construct in four dimensions. N=4 supersymmetric Yang--Mills (SYM) is the only known 4d theory for which there exists a lattice formulation that exactly preserves a subset of the supersymmetry algebra. This exact supersymmetry has remarkable consequences that permit practical lattice calculations. I will present results from ongoing numerical studies of lattice N=4 SYM, including comparisons with analytic predictions.

Confinement/deconfinement phase transition in SU(3) Yang-Mills theory in view of dual superconductivity.

Shibata, Akihiro (Computing Research Center, High Energy Accelerator Research Organization (KEK))

Abstract:

We give a non-Abelian dual superconductivity picture for quark confinement, and demonstrate the numerical evidences on the lattice: the non-Abelian magnetic monopole dominantly reproduces the string tension in the linear potential in SU(3) Yang-Mills theory, and that the SU(3) Yang-Mills vacuum is the type I dual superconductor profiled by the chromoelectric flux tube and themagnetic monopole current induced around it, which is a novel feature obtained by our simulations. Then, we discuss the confinement and deconfinement phase transition at finite temperature in view of the dual superconductivity. We investigate chromomagnetic monopole currents induced by chromo-magnetic flux in both confinement and deconfinement phase by the numerical simulations on a lattice at finite temperature, and discuss the role of the chromoelectric monopole in the confinement/deconfinement phase transition.

Some Recent Results on Strongly Coupled Gauge Theories

Shrock, Robert (Stony Brook University)

Abstract:

We discuss some recent results on strongly coupled gauge theories, including calculations of renormalization-group evolution, investigation of properties of exact and approximate fixed points, and ideas for physics beyond the Standard Model.

Separating Di-jet Resonances using the Color Discriminant Variable

Simmons, Elizabeth H(Michigan State University)

Abstract:

An exciting possibility for the upcoming 14 TeV run of the LHC is that a new strongly-coupled resonance decaying to dijets could be discovered. Once the resonance is detected, the immediate questions will be about the nature of the particle: is it colored? is it a vector, fermion, or scalar? does it couple to quarks in a flavor-universal way? This talk reviews the LHC discovery reach for a variety of dijet resonances and discusses a strategy for measuring the newly discovered state's properties. The method relies on the color discriminant variable, which can be readily at the LHC from the measurements of the di-jet signal cross section, the resonance mass and the resonance width. We discuss the ability of this method to distinguish between a qg excited quark resonance, a qqbar coloron, a qqbar Z', and a gg color-octet scalar. We also show how including information about the new resonance's decays to heavy flavor can probe questions related to flavor universality in the underlying theory.

Dynamical origin of the electroweak scale and the 125 GeV scalar

Tuominen, Kimmo (University of Helsinki)

Abstract:

We consider a fully dynamical origin for the masses of weak gauge bosons and heavy quarks of the Standard Model. Electroweak symmetry breaking and the gauge boson masses arise from new strong dynamics, which leads to the appearance of a composite scalar in the spectrum of excitations. In order to generate mass for the Standard Model fermions, we consider extended gauge dynamics, effectively represented by four fermion interactions at presently accessible energies. By systematically treating these interactions, we show that they lead to a large reduction of the mass of the scalar resonance. Therefore, interpreting the scalar as the recently observed 125 GeV state, implies that the mass originating solely from new strong dynamics can be much heavier, i.e. of the order of 1 TeV. In addition to reducing the mass of the scalar resonance, we show that the four-fermion interactions allow for contributions to the oblique corrections in agreement with the experimental constraints.
The couplings of the scalar resonance with the Standard Model gauge bosons and fermions are evaluated, and found to be compatible with the current LHC results.

Baryon spectrum in the composite sextet model

Wong, Chik Him (University of Wuppertal)

Abstract:

The strongly coupled near-conformal gauge theory with two fermion flavors in the two-index symmetric (sextet) representation of SU(3) is potentially a minimal realization of the composite Higgs mechanism. We discuss the staggered fermion construction of baryonic states, present our first numerical results and comment on implications for dark matter.

Linking U(2)xU(2) to O(4) via decoupling

Yamada, Norikazu (KEK)

Abstract:

The nature of chiral phase transition of massless two flavor QCD
depends on the fate of flavor singlet axial symmetry $U_A(1)$ at the
critical temperature ($T_c$).
Assuming that a finite $U_A(1)$ breaking remains at $T_c$, the
corresponding three dimensional effective theory is composed of four
massless and four massive scalar fields.
We study the renormalization group flow of the effective theory in the
$\epsilon$-expansion, using a mass dependent renormalization scheme,
and determine the region of the attractive basin flowing into the
$O(4)$ fixed point with a focus on its dependence on the size of the
$U_A(1)$ breaking.
The result is discussed from a perspective of the decoupling of massive
fields.
It is pointed out that, although the effective theory inside the
attractive basin eventually reaches the $O(4)$ fixed point, the
approaching rate, one of the universal exponents, is different from
that of the standard $O(4)$ model.
We present the reason for this peculiarity, and propose a novel
possibility for chiral phase transition in two-flavor QCD.

A symmetry breaking mechanism by parity assignment in the noncommutative Higgs model

Yang, Masaki J.S.(KEK)

Abstract:

We apply the orbifold GUT mechanism to the noncommutative Higgs model. An assignment of Z2 parity to the "pre-gauge fields" induces both of the parity assignments of the gauge and Higgs bosons, because these bosons are treated as some kind of composite fields in this formalism. As a result, a part of the gauge bosons and colored triplet Higgs boson receive heavy mass comparable to GUT scale, and the gauge symmetry is broken. No particle appear other than the SM ones in the massless states.