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A. Makhlin

Publications and source records attributed to A. Makhlin.

At least 19 recordsLinked to original sources
arXiv2001

Quantum collisions of finite-size ultrarelativistic nuclei

We show that the boost variable, the conjugate to the coordinate rapidity, which is associated with the center-of-mass motion, encodes the information about the finite size of colliding nuclei in a Lorentz-invariant way. The quasi-elastic forward color-changing scattering between the quantum boost states rapidly grows with the total energy of the collision and leads to an active breakdown of the color coherence at the earliest moments of the collision. The possible physical implications of this result are discussed.

hep-ph↗
arXiv2000

Scenario for Ultrarelativistic Nuclear Collisions: V. Onset of Deconfinement. (How the Nuclei Get Unbound.)

We consider a Euclidean extension of the wedge form of Hamiltonian dynamics, which explicitly accounts for the strong localization of the first interaction in nuclear collisions. A new principle of the analytic continuation via the tetrad vector is introduced. We discover the existence of self-dual solutions with short life-times (ephemerons) and conjecture that these vacuum fluctuations can lower the Euclidean action of the system of the colliding nuclei, thus enforcing a breakdown of the nuclei coherence. We suggest that the ephemerons can be identified with the gluons-partons, which are resolved in high-energy nuclear collisions.

hep-ph↗
arXiv2000

Scenario for Ultrarelativistic Nuclear Collisions: II. Geometry of quantum states at the earliest stage

We suggest that the ultrarelativistic collisions of heavy ions provide the simplest situation for the study of strong interactions which can be understood from first principles and without any model assumptions about the microscopic structure of the colliding nuclei. We argue that the boost-invariant geometry of the collision, and the existence of hard partons in the final states, both supported by the data, make a sufficient basis for the quantum theory of the phenomenon. We conclude that the quantum nature of the entire process is defined by its global geometry, which is enforced by a macroscopic finite size of the colliding objects. In this paper, we study the qualitative aspects of the theory and review its development in two subsequent papers. Our key result is that the effective mass of the quark in the expanding system formed in the collision of the two nuclei is gradually built up reaching its maximum by the time the quark mode becomes sufficiently localized. The chromo-magneto-static interaction of the color currents flowing in the rapidity direction is the main mechanism which is responsible for the generation of the effective mass of the soft quark mode and therefore, for the physical scale at the earliest stage of the collision.

hep-ph↗
arXiv2000

Scenario for Ultrarelativistic Nuclear Collisions: III. Gluons in the expanding geometry

We derive expressions for various correlators of the gauge field and find the propagators in Hamiltonian dynamics which employs a new gauge $A^τ=0$. This gauge is a part of the wedge form of relativistic dynamics suggested earlier as a tool for the study of quantum dynamics in ultra-relativistic heavy ion collisions. We prove that the gauge is completely fixed. The gauge field is quantized and the field of radiation and the longitudinal fields are unambiguously separated. The new gauge puts the quark and gluon fields of the colliding hadrons in one Hilbert space and thus allows one to avoid factorization.

hep-ph↗
arXiv2000

Scenario for Ultrarelativistic Nuclear Collisions: IV. Effective quark mass at the early stage

Using the framework of wedge dynamics, we compute the effective transverse mass of a soft quark mode propagating in the expanding background of hard quarks and gluons created at the earliest time of the collision. We discover that the wedge dynamics does not require any external infrared or collinear cut-off. The effective mass is produced mainly due to the forward quark-quark scattering mediated by the longitudinal (in sense of Gauss' law) magnetic fields. Contribution of the radiation field is parametrically suppressed.

hep-ph↗
arXiv1999

Transient topological objects in high energy collisions

The possible topology of quantum fluctuations which take place at the earliest stage of high-energy processes is studied. A new exact solution of Yang-Mills equations with fractional topological charge and carrying a single color is found.

hep-ph↗
arXiv1998

Sensitivity of HBT interferometry to the microscopic dynamics of freeze-out

We study the HBT interferometry of ultra-relativistic nuclear collisions using a freezeout model in which free pions emerge in the course of the last binary collisions in the hadron gas. We show that the HBT correlators of both identical and non-identical pions change with respect to the case of independent pion production. Practical consequences for the design of the event generator with the built in Bose-Einstein correlations are discussed. We argue that the scheme of inclusive measurement of the HBT correlation function does not require the symmetrization of the multi-pion transition amplitudes (wave-functions).

hep-ph↗
arXiv1998

Scenario for Ultrarelativistic Nuclear Collisions: Space--Time Picture of Quantum Fluctuations and the Birth of QGP

We study the dynamics of quantum fluctuations which take place at the earliest stage of high-energy processes and the conditions under which the data from e-p deep-inelastic scattering may serve as an input for computing the initial data for heavy-ion collisions at high energies. Our method is essentially based on the space-time picture of these seemingly different phenomena. We prove that the ultra-violet renormalization of the virtual loops does not bring any scale into the problem. The scale appears only in connection with the collinear cut-off in the evolution equations and is defined by the physical properties of the final state. In heavy-ion collisions the basic screening effect is due to the mass of the collective modes (plasmons) in the dense non-equilibrium quark-gluon system, which is estimated. We avoid the standard parton phenomenology and suggest a dedicated class of evolution equations which describe the dynamics of quantum fluctuations in heavy-ion collisions.

hep-ph↗
arXiv1996

QCD evolution with longitudinal fields and heavy quarks

QCD evolution equations that naturally include longitudinal (non-propagating) fields and heavy quarks are derived. We start with the integral equations of quantum field kinetics and obtain the master equations, similar to DGLAP evolution equations after several consecutive approximations. We demonstrate that in their primary form, the evolution equations include a new element, feed-back via longitudinal fields, leading to a low-x enhancement in the e-p DIS cross section. We show that the structure function F_L is very sensitive to the dynamics of the longitudinal fields and that the heavy quarks in evolution equations make this effect even more pronounced.

hep-ph↗
arXiv1996

A theoretical view of practical problems in interferometry

Interferometry is discussed in terms of the representation of the source. In particular, scale-invariant 1-d hydrodynamics is revisited, and extended to the case of unequal transverse masses. It is argued that that kaon emission occurs over a short time interval. Exact results for models of two- and three-dimensional flow are presented, which exhibit altered scaling laws. Such qualitative trends, together with other observables, are vital if one is to draw conclusions about the source.

nucl-th↗
arXiv1996

The wedge form of relativistic dynamics

It is commonly accepted that in hadronic or nuclear collisions at extremely high energies the shortest scales are explored. At the classical level, this property of the interaction is closely related to the Lorentz contraction of the fields of colliding particles which provides instantaneous switching the interaction on. I argue that the underlying quantum dynamics should be confined to within the light wedge of the two-dimensional plane where the first interaction takes place and suggest to include this property as the boundary condition for the quantum field theory which describes the collision process. Connection between the type of inclusive process and the temporal order of its dynamical evolution is discussed. The one-particle states and propagators of the perturbation theory for the scalar and fermion fields are found.

hep-ph↗
arXiv1996

The Wedge Form of relativistic Dynamics. II. The Gluons

I derive expressions for various correlators of the gauge field and find propagators in a new gauge A^τ=0. This gauge is a part of the wedge form of relativistic dynamics suggested earlier as the tool for the study of quantum dynamics in collisions of hadrons at extremely high energies and in ultrarelativistic heavy ion collisions. The new gauge puts the quark and gluon fields of the colliding hadrons in one Hilbert space and thus allows one to avoid factorization.

hep-ph↗
arXiv1994

Boson Interferometry after SPS and before RHIC

We re--examine the connection between interferometry and the Wigner representation for source freeze--out, and continuous emission. At the operator level, two equivalent representations of the two--particle spectrum are found, which contradict the standard expression of kinetic theory. The discrepancy is resolved using two toy models. Further, we revisit interferometry in scale--invariant one--dimensional hydrodynamics, and argue that recent experimental results are evidence for a short kaon emission time. Using two exactly calculable models of two-- and three--dimensional flow, it is shown that the saddle point approximation, which is reasonable for one--dimensional flow, is no longer adequate. In these models the scaling law is altered, and we argue that such qualitative trends, together with other observables, are vital if one is to draw conclusions about the unknown source parameters.

hep-ph↗
arXiv1994

Quantum Field Kinetics

Using the general framework of quantum field theory, we derive basic equations of quantum field kinetics. The main goal of this approach is to compute the observables associated with a quark-gluon plasma at different stages of its evolution. We start by rewriting the integral equations for the field correlators in different forms, depending on the relevant dynamical features at each different stage. Next, two versions of perturbation expansion are considered. The first is best suited for the calculation of electromagnetic emission from chaotic, but not equilibrated, strongly interacting matter. The second version allows one to derive evolution equations, which are generalizations of the familiar QCD evolution equations, and provide a basis for the calculation of the initial quark and gluon distributions after the first hard interaction of the heavy ions.

hep-ph↗
arXiv1994

Quark and gluon distributions at the earliest stage of heavy ion collision

Using the general framework of quantum field kinetics we consider new principles to compute initial distribution of quarks and gluons after the first hard interaction of heavy ions. We start by rewriting the integral equations of QCD in the form which is generalizations of the familiar QCD evolution equations. These equations describe both space-time-- and $(x,Q^2)$--evolution before the collision, and allow one to use the $ep$ DIS data without reference to parton phenomenology. New technique generate perturbation theory that avoid double count of the processes, does not contain an artificial factorization scale, and does not require low-momentum cut-offs since infrared behavior is controlled by the DIS data.

hep-ph↗
arXiv1993

Low-mass dileptons from nonequilibrium QGP

The rate of the emission of the high energy low-mass dileptons from the QGP is found in the first nonvanishing order with respect to strong coupling. We base on the real-time kinetic approach [2] without an explicit assumption about a complete thermal equilibrium in the emitting system. For the class of the partons distributions which may simulate that of the "hot glue scenario"[1] the rate of emission is found analytically . ( Figures can be obtained from the author )

hep-ph↗
arXiv1993

Nonequilibrium Quantum Field Kinetics

Using the general framework of nonequilibrium statistical mechanics for relativistic quantum field systems we derive the basic equations of quantum field kinetics. The main aim of the approach is calculation of observables associated with quark-gluon plasma which is out of thermal and chemical equilibrium. We show that in the regime of high rate of the phase and statistical mixing the perturbation theory for many-body quantum field system should have the form which much differs from the standard expansion in powers of coupling constant. ( Figures can be obtained from the author )

hep-ph↗