Yukinao Akamatsu, KMI, Nagoya U
Chiral plasma instabilities for Abelian and non-Abelian gauge fields
Recently, kinetic theory of chiral fermions has been developed. Spin of chiral fermions introduces an interesting nontrivial structure in the phase space: Berry connection in the momentum space in the monopole configuration. This new kinetic theory can describe the axial U(1) anomaly and the so-called chiral magnetic effect. In this talk, we consider QED and QCD plasmas with massless fermions and apply the new kinetic theory to the dynamics of gauge fields. When there is an imbalance between left-handed and right-handed fermions (chirality imbalance), we find that the gauge field becomes unstable. We call this instability chiral plasma instability. The unstable mode grows so as to reduce the chiral imbalance, which is the source of the instability. The effect of collisions is relevant for the instability of the QCD plasma while it is not for the QED plasma. We also develop an effective chiral Langevin theory for non-Abelian gauge fields in QCD plasma that describes both the chiral plasma instability and soft collisions.
Tatsuma Nishioka, The Univ. of Tokyo
Entanglement Entropy in Gapped System
Entanglement entropy is a useful order parameter charactering phases in quantum field theories in various dimensions. For example, it can capture confinement/deconfinement and quantum phase transitions. The analytic computations, however, are limited to special cases such as conformal and free field theories. In this talk, I would like to elucidate various properties of entanglement entropy in gapped systems by using both field theoretic and holographic approaches. I will also discuss how entanglement entropy behaves under a perturbation of CFT by a relevant operator and point out that the perturbative calculation may fail depending on the conformal dimension.
Toshifumi Yamada, NCU, Taiwan
T-odd asymmetry in W+jet events at the LHC
W bosons produced at high transverse momentum in hadron collisions can
have polarization along the direction perpendicular to the production
plane, which is odd under naive-T-reversal where both the
three-momenta and angular momenta are reversed. Perturbative QCD
predicts non-zero polarization at the one-loop level, which can be
measured as parity-odd components in the angular distribution of
charged leptons from the decay of W bosons. We perform a
detector-level simulation with the generator aMC@NLO, and demonstrate
that the asymmetry can be observed at the 8 TeV LHC with 20 fb^-1 of
data. If confirmed, it will be the first experimental measurement of
the sign of the imaginary part of one-loop QCD amplitudes.
Khaiming Wong, Universiti Sains Malaysia(USM) MALAYSIA School of Physics
Half-Integer Magnetic Monopole and Dyon Solutions in the SU(2) Yang-Mills-Higgs Theory
We review magnetic monopoles and dyons of one-half topological charge with finite energy in the SU(2) Yang-Mills-Higgs theory.
The half-monopole can exist individually, where it is located at the origin of the coordinate axes r = 0. It can also coexist with a ‘t Hooft-Polyakov monopole, with the one-monopole with charge +1 at the positive z-axis and a half-monopole with charge – ½ at the origin.
Both of these axially symmetric configurations possess finite total energy and magnetic dipole moment. The total energy is found to increase with the strength of the Higgs field self-coupling constant λ. The magnetic dipole moment and the dipole separation (one plus half-monopole) decrease with λ. Both the two configurations are non-BPS solutions even in the BPS limit when the Higgs self-coupling constant vanishes. By switching on the time component of the Yang-Mills potential, electric charge is introduced into the system, where we now have half-dyon and one plus half-dyon.
Besides possessing electric charge which varies with λ and electric charge parameter η, the configurations also exhibit critical behaviour in total energy, electric charge, and dipole moment, when η→1.
Gabriel Catren, Laboratoire SPHERE, Université Paris Diderot - CNRS, Paris, France
On the Relation Between Gauge and Phase Symmetries
We propose a group-theoretical interpretation of the fact that the transition from classical to quantum mechanics entails a reduction in the number of observables needed to define a physical state (e.g. from q and p to q or p in the simplest case). We argue that, in analogy to gauge theories, such a reduction results from the action of a symmetry group. To do so, we propose a conceptual analysis of formal tools coming from symplectic geometry and group representation theory, notably Souriau’s moment map, the Mardsen–Weinstein symplectic reduction, the symplectic “category” introduced by Weinstein, and the conjecture (proposed by Guillemin and Sternberg) according to which “quantization commutes with reduction”. In particular, we argue that phase invariance in quantum mechanics and gauge invariance have a common geometric underpinning, namely the symplectic reduction formalism. This stance points towards a gauge-theoretical interpretation of Heisenberg indeterminacy principle. We revisit (the extreme cases of) this principle in the light of the difference between the set-theoretic points of a phase space and its category-theoretic symplectic points.
Keitaro Nagata, KEK
Canonical approach to finite density QCD
Recently, QCD at finite temperature and density attracts renewed interests, stimulated by advances in lattice QCD technique for finite density system and a beam energy scan (BES) program, which is an on-going experiment at RHIC to investigate the QCD phase diagram.
Towards the understanding of QCD at finite density, we employ a canonical approach, which is based on a fundamental equation describing the relation between canonical and grand canonical partition functions. I will talk about its applications both to BES experiment and lattice QCD simulations.
First, we introduce the framework and explain possible applications, such as moments of the probability distribution and Lee-Yang zeros. Then, we apply the technique to data obtained in BES experiments. We show that the canonical approach enables us to investigate a wide range of QCD phase diagram using data obtained at a certain point (chemical freeze-out point).
Next, we study canonical partition functions and Lee-Yang zeros in lattice QCD simulations. They show a drastic change from the confinement to deconfinement phases. In addition, we analytically solve canonical partition functions and Lee-Yang zeros for high temperature QCD using a saddle point approximation. We find that the analytic result of Lee-Yang zeros explain a gross feature of those obtained from lattice QCD simulations. We discuss its implications to experimental data.
References
1. Lee-Yang zero distribution of high temperature QCD and Roberge-Weiss phase transition
K. Nagata, K. Kashiwa, A. Nakamura, S. M. Nishigaki arXiv:1410.0783
2. Probing QCD Phase Structure by Baryon Multiplicity Distribution A. Nakamura, K. Nagata [arXiv:1305.0760]
3. Towards extremely dense matter on the lattice K. Nagata, S. Motoki, Y. Nakagawa, A. Nakamura, T.Saito [PTEP01A103(2012), arXiv:1204.1412]
Kazumi Kashiyama, University of California, Berkeley
Neutrino Tomography of GRB jet
The IceCube discovery of astrophysical sub-PeV neutrinos has opened a new era of multi-messenger astronomy. Relativistic GRB jets are a long-standing candidate source of such neutrinos, although no neutrino counterpart of the observed GRBs has been reported so far. Here, I overview possible neutrino production processes in GRB jet, and argue how far detections or even non-dentecions of such neutrino counterparts, combined with multi-band electromagnetic observations, can shape the physics of GRB jet in the next decade.
Dan Hooper, Fermi National Accelerator Laboratory
Dark matter Annihilation in the Galactic Center
Past studies have identified a spatially extended excess of ~1-3 GeV gamma rays from the region surrounding the Galactic Center, consistent with the emission expected from annihilating dark matter. Recent improvements in the analysis techniques have found this excess to be robust and highly statistically significant, with a spectrum, angular distribution, and overall normalization that is in good agreement with that predicted by simple annihilating dark matter models. For example, the signal is very well fit by a 31-40 GeV dark matter particle annihilating to b quarks with an annihilation cross section of sigma v = (1.7-2.3) x 10^-26 cm^3/s. Furthermore, the angular distribution of the excess is approximately spherically symmetric and centered around the dynamical center of the Milky Way (within ~0.05 degrees of Sgr A*), showing no sign of elongation along or perpendicular to the Galactic Plane. The signal is observed to extend to at least 10 degrees from the Galactic Center, disfavoring the possibility that this emission originates from millisecond pulsars.
Keiju Murata, Keio U
Electric Field Quench in AdS/CFT
An electric field quench, a suddenly applied electric field, can induce nontrivial dynamics in confining systems which may lead to thermalization as well as a deconfinement transition. In order to analyze this nonequilibrium transitions, we use the AdS/CFT correspondence for N=2 supersymmetric QCD that has a confining meson sector. We find that the electric field quench causes the deconfinement transition even when the magnitude of the applied electric field is smaller than the critical value for the static case (which is the QCD Schwinger limit for quark-antiquark pair creation). The time dependence is crucial for this phenomenon, and the gravity dual explains it as the weakly turbulent instability of a D-brane in the bulk AdS spacetime. Interestingly, the d econfinement time takes only discrete values as a function of the magnitude of the electric field. We advocate that the new deconfinement phenomenon is analogous to the exciton Mott transition.
Kantaro Ohmori, The Univ. of Tokyo
Anomaly polynomial of general 6d SCFTs
