Tigran Kalaydzhyan

Fluid-gravity model for the chiral magnetic effect

We consider the STU model as a gravity dual of a strongly coupled plasma with multiple anomalous U(1) currents. In the bulk we add additional background gauge fields to include the effects of external electric and magnetic fields on the plasma. Reducing the number of chemical potentials in the STU model to two and interpreting them as quark and chiral chemical potential, we obtain a holographic description of the chiral magnetic and chiral vortical effects (CME and CVE) in relativistic heavy-ion collisions. These effects formally appear as first-order transport coefficients in the electromagnetic current. We compute these coefficients from our model using fluid-gravity duality. We also find analogous effects in the axial-vector current. Finally, we briefly discuss a variant of our model, in which the CME/CVE is realized in the late-time dynamics of an expanding plasma.

Magnetic-field-induced insulator-conductor transition in SU(2) quenched lattice gauge theory.

We study the correlator of two vector currents in quenched SU(2) lattice gauge theory with a chirally invariant lattice Dirac operator with a constant external magnetic field. It is found that in the confinement phase the correlator of the components of the current parallel to the magnetic field decays much slower than in the absence of a magnetic field, while for other components the correlation length slightly decreases. We apply the maximal entropy method to extract the corresponding spectral function. In the limit of zero frequency this spectral function yields the electric conductivity of quenched theory. We find that in the confinement phase the external magnetic field induces nonzero electric conductivity along the direction of the field, transforming the system from an insulator into an anisotropic conductor. In the deconfinement phase the conductivity does not exhibit any sizable dependence on the magnetic field.

Anisotropic hydrodynamics, holography and the chiral magnetic effect

We discuss a possible dependence of the chiral magnetic effect (CME) on the elliptic flow coefficient v2. We first study this in a hydrodynamic model for a static anisotropic plasma with multiple anomalous U(1) currents. In the case of two charges, one axial and one vector, the CME formally appears as a first-order transport coefficient in the vector current. We compute this transport coefficient and show its dependence on v2. We also determine the CME-coefficient from first-order corrections to the dual AdS background using the fluid-gravity duality. For small anisotropies, we find numerical agreement with the hydrodynamic result.

Temperature dependence of the chiral vortical effects

We discuss the origins of temperature dependence of the axial vortical effect, i.e. generation of an axial current in a rotating chiral medium along the rotation axis. We show that the corresponding transport coefficient depends, in general, on the number of light weakly interacting degrees of freedom, rather than on the gravitational anomaly. We also comment on the role of low-dimensional defects in the rotating medium, and appearance of the chiral vortical effect due to them.

Collective flow in high-multiplicity proton-proton collisions

We present an evidence of strong radial flow in high-multiplicity pp collisions. We analyze the CMS data on the inclusive spectra of the charged pions, kaons and protons in the LHC

Constraining the primordial power spectrum from SNIa lensing dispersion

\sqrt{s}=7

Fractal dimension of the topological charge density distribution in SU(2) lattice gluodynamics

TeV collisions. For

Gravity waves generated by sounds from big bang phase transitions

\gtrsim 75

On chromoelectric (super)conductivity of the Yang-Mills vacuum

we demonstrate the consistency of the hydrodynamic description with the (idealized) Gubsers flow. Using a one parameter fit of the model to experimental data, we obtain the initial fireball size to be of the order of 1 fm. At smaller multiplicities, the fit cannot be performed which shows a limitation of the hydrodynamic approach and provides us with falsifiability of our theory.

Extracting dark matter signatures from atomic clock stability measurements

The (absence of detecting) lensing dispersion of Supernovae type Ia (SNIa) can be used as a novel and extremely efficient probe of cosmology. In this preliminary example we analyze its consequences for the primordial power spectrum. The main setback is the knowledge of the power spectrum in the non-linear regime, 1 Mpc^{-1} < k < 10^2-10^3 Mpc^{-1} up to redshift of about unity. By using the lensing dispersion and conservative estimates in this regime of wavenumbers, we show how the current upper bound sigma_mu(z=1) < 0.12on existing data gives strong indirect constraints on the primordial power spectrum. The probe extends our handle on the spectrum to a total of 12-15 inflation e-folds. These constraints are so strong that they are already ruling out a large portion of the parameter space allowed by PLANCK for running alpha = d n_s / d ln k and running of running beta = d^2 n_s / d ln k^2. The bounds follow a linear relation to a very good accuracy. A conservative bound disfavors any enhancement above the line beta(k_0)=0.036-0.42 alpha(k_0) and a realistic estimate disfavors any enhancement above the line beta(k_0)=0.022-0.44 alpha(k_0).