A scheme of calculation of large-Nc masses of light mesons from
the planar QCD sum rules is discussed. We will present two methods based on the use of linear radial Regge trajectories with a special emphasis on the scalar sector.
Right since its discovery in 2003 by the Belle collaboration, establishing the nature of the $X(3872)$ meson has been one of the main priorities in the field of quarkonium physics. Not qualifying as a conventional $c\bar{c}$ state, the multiquark structure of this exotic meson has received very different interpretations, ranging from a compact tetraquark configuration to an extended $D\bar...
We consider holographic description of heavy ions collisions. The dependence of total multiplicity on the energy forcing us to deal with anisotropic holographic models. We derive the holographic renorm group flow (HRGF) equations in the presentce of anisotropy and a non-zero chemical potential. We show that in particular cases HRGFs reproduce the QCD RGFs. We consider the behaviour of the...
The study of forward-backward correlations between observables from separated rapidity intervals is considered as a sensitive tool for observing the collective phenomena in the ultrarelativistic collisions of hadrons and nuclei and for investigation of the initial stages of the hadronic interaction. The selection of a large gap between rapidity intervals facilitates the elimination of the...
In the framework of the model with quark-gluon strings considered as color flux tubes we study the correlations between various observables in two acceptance windows separated in rapidity and azimuth, used in the analysis of the multiparticle production in hadronic interactions at high energy. To take into account the string fusion effects leading to a formation of string clusters with new...
A quantum gas of interacting relativistic effective massive mesons at finite temperature (either at approximate thermal equilibrium or off-equilibrium), ressembling qualitatively those produced in a heavy-ion collision, is described by a scalar renormalizable relativistic quantum field theory (RRQFT) with quartic self-interaction, in (1+3)-dimensional Minkowski space.
A short discussion of...
The thermalization of particles produced in collisions of small systems can be achieved by quantum entanglement of the partons of the initial state. We study the transverse momentum distributions in pp and PbPb collisions at different energies and centralities, observing in all cases a relation between the effective thermal temperature of the low pt spectrum and the hard scale of the high pt...
The scalar-isoscalar mode of QCD is expected to become very light close to the second-order chiral critical point. This mode is the main responsible for the attractive part of the nucleon-nucleon potential at distances of 1-2 fm. Therefore, a strong long-range attraction among nucleons is predicted to develop close to the QCD critical point. Using the Walecka-Serot model for the NN interaction...
We compare Chiral Perturbation Theory (ChPT) and the Linear Sigma Model
(LSM) as realizations of low energy QCD for light mesons in a chirally imbalanced
medium. The relations between the phenomenological low-energy constants of the
Chiral Lagrangian and the corresponding constants of the Linear Sigma Model are
established as well as the expressions for the decay constant of the pi-meson in...
We analyze the low lying spectrum of SU(N) gauge theories on a 2-dimensional spatial torus in a singular large N limit obtained by sending the rank of the group to infinity while shrinking the size of the torus to zero. The absence of tachyonic instabilities along the process leads to constraints on the possible values of N and the magnetic flux on the torus, singling out a limiting sequence...
Many non-Hermitian but PT-symmetric Hamiltonians produce the quantum evolution that is unitary under the non-standard inner product. This allows us to interpret them in the pseudo-Hermitian way and relate to the well-behaved but very complicated quantum models through the non-unitary transformation. However for the generic PT-symmetric quantum field theory this transformation becomes non-local...
Quantum field theory in curved space-time and quantum gravity predict one-loop quantum corrections to the R+R^2 (Starobinsky) inflationary model. Observational consequences of a number of such corrections are considered. One of them – the form of the Fourier power spectrum of primordial scalar (matter density) perturbations – has been actually measured and has appeared to be in the excellent...
The method proposed by K. Symanzik for constructing quantum field models in an inhomogeneous space-time is used to describe the interaction of the quantum electrodynamics (QED) fields with extended material objects. It is carried out within the framework of quantum field models in which the QED Lagrangian is modified according to the QED basic principles (locality, gauge invariance,...
Recent BFKL evolution developments are briefly reviewed. BFKL evolution manifestations at high energies are discussed.
With the reported observation of the Higgs boson at the LHC, the Standard Model of particle physics seems to be complete now as for its particle content. However, several experimental data at low and intermediate energies indicate that there may be two surprises.
The strongest evidence concerns $E(38)$, a very light spinless boson, probably a scalar, with a mass of 38 MeV and decaying into...
We construct hyperasymptotic expansions for the static potential and the pole mass. We then compare the theoretical predictions with lattice data and the large $\beta_0$ approximation.
The asymptotic structure of the perturbative relation between $\bar{MS}$ and on-shell heavy quark masses is considered in QCD at the O(\alpha_s^6) level. The flavour-dependence of the considered PT corrections is analysed. In higher orders this dependence is estimated using three techniques, namely the effective charges motivated approach, the encoded in the asymptotic formula infrared...
We suggest a novel view on non-renormalizable interactions. It is based on the usual BPHZ R-operation which is equally applicable to any local QFT independently of whether it is renormalizable or not. As a playground we take the \phi^4_D theory in D dimensions for D=4,6,8,10 and consider the four-point scattering amplitude on shell. We derive the generalized RG equation and find the...
We analyze the unitarity properties of higher derivative quantum
field theories which are free of ghosts and ultraviolet singularities.
We point out that in spite of the absence of ghosts most of these
theories are not unitary. This result confirms the difficulties of
finding a consistent quantum field theory of quantum gravity.
We present an analogy between multiparticle production in proton-proton collisions at the LHC and the time evolution of the early universe. In particular we focus on long-range angular correlations of the CMB on the one hand, and particle emission in pp interactions on the other hand, pointing out suggestive connections between both physical cases. Moreover, we show how the analysis of angular...
We study the consequences of (beyond) positivity of scattering amplitudes in the effective field theory description of the Higgs-Dilaton inflationary model. By requiring the EFT to be compatible with a unitary, causal, local and Lorentz invariant UV completion, we derive constraints on the Wilson coefficients of the first higher order derivative operators. We show that the values allowed by...
In the framework of such basic principles as local gauge invariance, unification of the weak and electromagnetic interactions and spontaneous symmetry breaking in the Standard Model the most economical and simplest possibilities are realized. We discuss the problem of neutrino masses from the point of view of economy and simplicity. It is unlikely that neutrino masses are of the same SM...
I study neutrino oscillations driven by a plane gravitational wave. First, I consider neutrino spin oscillations in this gravitational background. I derive the covariant equation for the neutrino spin evolution in a magnetic field and background matter in curved space-time. Then I discuss a particular situation when a neutrino interacts with matter, a transverse magnetic field and a...
Sterile neutrino is one of the well motivated candidate to form the
Dark Matter component in the Universe. We discuss standard mechanisms
of dark matter production in the early Universe and its modifications
in the presence of cosmic scalar field.
We perform canonical analysis of a model in which gravity is coupled to a circular dust shell in 2+1 spacetime dimensions.
The result is a reduced action depending on a finite number of degrees of freedom.
The emphasis is made on finding canonical variables providing the global chart for the entire phase space of the model.
It turns out that all the distinct pieces of momentum space could be...
I will explain how theories with analytic functions of derivatives are
connected to strings and in particular arise in string field theory
(SFT) and will spent the most part of my talk on the good
and unrevealed properties of analytic infinite derivative (AID) gravity.
In particular, I will discuss questions of avoiding singularities as
well as possible observational evidences for such a...
I describe quantization of bosonic string about the mean-field ground state, which turns out to be stable in the target-space dimension 2 < d < 26 contrary to the usual classical ground state which is stable only for d<2, and discuss how this resolves some old problems with strings. I compute the string susceptibility index gamma_{str} in the mean-field approximation and demonstrate that it...
In the past I derived from QFT the generating functional of Green functions in a fermionic medium. Based on this many-body scheme I give an algebraic derivation from first principles of the purely diagrammatical method introduced by N. Kaiser [NPA860,411(2011)] to resum the ladder diagrams for the calculation of the energy per particle in a fermionic environment, including only a constant...
The properties of the core-crust transition in neutron stars are investigated
using effective nuclear forces of finite-range. Special attention is paid to the
so-called dynamical method for locating the transition point, which, apart from the stability of the uniform nuclear matter against clusterization, also considers contributions due to finite-size effects.In particular, contributions to...
The Chandrasekhar-Friedman-Schutz (CFS) instability consist in enhancement of perturbations in a rotating star by emission of gravitational waves. In absence of dissipation, all rotating stars should be unstable and the emission of gravitational waves should spin down them rapidly. Observations of rapidly rotating neutron stars indicates that it is not a case and dissipative processes...
Pulsar Timing Arrays have yet to find convincing evidence of gravitational waves. Some time ago it was pointed out by one of the authors that a dramatic enhancement of the signal would take place for particular values of the angle subtended by the source and the observed pulsar. This enhancement is due to the fact that waves propagate in a Friedmann-Lemaitre-Robertson-Walker metric where,...
We consider the multifield models and modified gravity theories associated with them. Generalization of the superpotential method to multifield cosmological models is performed and the method of construction of exact solutions is developed. New classes of exact solutions in the two-component models connected with a f(R) gravity model with an additional scalar field have been constructed. and...
