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B. L. Ioffe

Publications and source records attributed to B. L. Ioffe.

At least 19 recordsLinked to original sources
arXiv2013

On the world cognizability

The paper gives a few examples of the phenomena that will never be understood by the mankind. The first example is the physics at the scales of $\sim 10^{-33}$ cm where the gravitation interaction becomes strong, sales at the very beginning of the Big Bang. It argues that the mankind will never establish the laws that controls the events at these scales. Further, it is supposed that the time dependence of the entropy, which determine the direction of the time arrow, originates at the same time scale and, thus, the nature of the time arrow will be never established either. Finally, I conjecture that the brain cells are controlled by quantum computer with the very large (or even infinite) number of degenerate states. An external observation destroys this degeneracy, leading to impossibility to understand the mechanism of the conscience.

physics.gen-ph↗
arXiv2012

The first dozen years of the history of ITEP Theoretical Physics Laboratory

The theoretical investigations at ITEP in the years 1945-1958 are reviewed. There are exposed the most important theoretical results, obtained in the following branches of physics: 1) the theory of nuclear reactors on thermal neutrons; 2) the hydrogen bomb project ("Tube" in USSR and "Classical Super" in USA); 3) radiation theory; ~4) low temperature physics; 5) quantum electrodynamics and quantum field theories; 6) parity violation in weak interactions, the theory of $β$-decay and other weak processes; 7) strong interaction and nuclear physics. To the review are added the English translations of few papers, originally published in Russian, but unknown (or almost unknown) to Western readers.

physics.hist-ph↗
arXiv2010

Chirality violating condensates in QCD and their connection with zero mode solutions of quark Dirac equations

It is demonstrated, that chirality violating condensates in massless QCD arise entirely from zero mode solutions of Dirac equations in arbitrary gluon fields. The model is suggested, where the zero mode solutions are the ones for quarks, moving in the instanton field. Basing on this model were calculated the quark condensate magnetic susceptibilities of dimensions $3(χ)$ and 5 ($κ$ and $ξ$). The good considence of the values $χ,κ$ and $ξ$, obtained in this approach with ones, found from the hadronic spectrum ia a serious argument in favour, that instantons are the only source of chirality violating condensates in QCD. The temperature dependence of the quark condensate is discussed. It is shown that the phase transition, corresponding to the $T$-dependence of the quark condensate $α(T)$ as an order parameter, is of the type of crossover.

hep-ph↗
arXiv2008

Axial anomaly in quantum electro- and chromodynamics and the structure of the vacuum in quantum chromodynamics

In this report, I discuss the current state of the problem of the axial anomaly in quantum electrodynamics (QED) and quantum chromodynamics (QCD) and how the axial anomaly is related to the structure of the vacuum in QCD. In QCD, the vacuum average of the axial anomaly is proportional to a new quantum number n, the winding number. The axial anomaly condition implies that there are zero modes of the Dirac equation for a massless quark and that there is spontaneous breaking of chiral symmetry in QCD, which leads to the formation of a quark condensate. The axial anomaly can be represented in the form of a sum rule the structure function in the dispersion representation of the axial -- vector -- vector (AVV) vertex. On the basis of this sum rule, it is calculated the width of the π^0\to 2γdecay with an accuracy of 1.5%. It is demonstrated, that 't Hooft conjecture -- the singularities of the amplitudes calculated in perturbative QCD on quark-gluon basis should reproduce themselves in calculations on the hadrons basis -- is not fulfilled generally.

hep-ph↗
arXiv2008

Spontaneous violation of chiral symmetry in QCD vacuum is the origin of baryon masses and determines baryon magnetic moments and their other static properties

A short review is presented of the spontaneous violation of chiral symmetry in QCD vacuum. It is demonstrated, that this phenomenon is the origin of baryon masses in QCD. The value of nucleon mass is calculated as well as the masses of hyperons and some baryonic resonances and expressed mainly through the values of quark condensates -- $<0\mid \bar{q} q \mid 0>, ~q=u,d,s$ -- the vacuum expectation values (v.e.v.) of quark field. The concept of vacuum expectation values induced by external fields is introduced. It is demonstrated that such v.e.v. induced by static electromagnetic field results in quark condensate magnetic susceptibility, which plays the main role in determination of baryon magnetic moments. The magnetic moments of proton, neutron and hyperons are calculated. The results of calculation of baryon octet $β$-decay constants are also presented.

hep-ph↗
arXiv2007

Axial anomaly and the precise value of the $π^0 \to 2 γ$ decay width

The anomaly in the vacuum expectation value of the product of axial and two vector currents (AVV) in QCD is investigated. The goal is to determine from its value the $π^0 \to 2 γ$ decay width with high precision. The sum rule for AVV formfactor is studied. The difference $f_{π^0} - f_{π^+}$ caused by strong interaction is calculated and appears to be small. The $π^0 - η$ mixing is accounted. The $π^0 \to 2 γ$ decay width determined theoretically from the axial anomaly is found to be $Γ(π^0 \to 2 γ) = 7.93 eV$ with an error $\sim 1.5%$. The measurement of the $π^0 \to 2 γ$ decay width at the same level of accuracy would allow one to achieve a high precision test of QCD.

hep-ph↗
arXiv2006

Axial anomaly: the modern status

The modern status of the problem of axial anomaly in QED and QCD is reviewed. Two methods of the derivation of the axial anomaly are presented: 1) by splitting of coordinates in the expression for the axial current and 2) by calculation of triangle diagrams, where the anomaly arises from the surface terms in momentum space. It is demonstrated, that the equivalent formulation of the anomaly can be given, as a sum rule for the structure function in dispersion representation of three point function of AVV interaction. It is argued, that such integral representation of the anomaly has some advantages in the case of description of the anomaly by contribution of hadronic states in QCD. The validity of the t'Hooft consistency condition is discussed. Few examples of the physical application of the axial anomaly are given.

hep-ph↗
arXiv2006

On the Current Correlators at Low Temperature

It is demonstrated, that the calculations of current correlators at low $T$, performed in Ref.'s \cite{1},\cite{2},\cite{3a} by the methods of current algebra, are correct contrary to the statements of the recent paper by Mallik \cite{3}.

hep-ph↗
arXiv2006

The origin of mass and the experiments on future high energy accelerators

The visible universe - it is the universe of nucleons and electrons. The appearance of nucleon mass is caused by the violation of chiral symmetry in quantum chromodynamics (QCD). For this reason, the experiments on high energy accelerators cannot shed light on the origin of the matter in the visible universe. The origin of the mass of matter will be clarified, when the mechanism of chiral symmetry violation in QCD will be elucidated.

hep-ph↗
arXiv2005

Hans Bethe and the Global Energy Problems

Bethe's view-point on the global energy problems is presented. Bethe claimed that the nuclear power is a necessity in future. Nuclear energetic must be based on breeder reactors. Bethe considered the non-proliferation of nuclear weapons as the main problem of long-range future of nuclear energetics. The solution of this problem he saw in heavy water moderated thermal breeders, using uranium-233, uranium-238 and thorium as a fuel.

physics.soc-ph↗
arXiv2005

Pentaquark decay is suppressed by chirality conservation

It is shown, that if the pentaquark $Θ^+ = uudd\bar{s}$ baryon can be represented by the local quark current $η_Θ$, its decay $Θ^+ \to n K^+ (p K^0)$ is forbidden in the limit of chirality conservation. The $Θ^+$decay width $Γ$ is proportional to $α^2_s < 0 | \bar{q} q | 0 >^2$, where $<0 | \bar{q} q | 0 >$, $q = u,d,s$ is quark condensate, and, therefore, is strongly suppressed. Also the polarization operator of the pentaquark current with isospin 1 is calculated using the operator product expansion and estimation for it mass is obtained .

hep-ph↗
arXiv2005

Resonance radiative decays as a tool for its parity determination

Radiative decays of the spin 1/2 baryonic resonances R with the decay mode R -> KN in case of small energy release are considered. Pentaquark is an example of such resonance. It is shown that in case of positive resonance parity corrections to the soft photon radiation formula are large even at low photon energies > 20 MeV and structure terms contributions may be essential, if R size > 1 fm. This effect is absent in case of negative parity. Particularly, measurements of the gamma spectrum in pentaquark radiative decays may allow us to determine its parity.

hep-ph↗
arXiv2005

QCD at Low Energies

The modern status of basic low energy QCD parameters is reviewed. It is demonstrated, that the recent data allows one to determine the light quark mass ratios with an accuracy 10-15%. The general analysis of vacuum condensates in QCD is presented, including those induced by external fields. The QCD coupling constant alpha_s is found from the tau-lepton hadronic decay rate. V-A spectral functions of tau-decay are used for construction of the V-A polarization operator Pi_{V-A}(s) in the complex s-plane. The operator product expansion (OPE) is used up to dimension D=10 and the sum rules along the rays in the complex s-plane are constructed. The best values of quark condensate and alpha_s<0|qq|0>^2 are found. The value of quark condensate is confirmed by considering the sum rules for baryon masses. Gluon condensate is found in four ways: by considering of V+A polarization operator based on the tau-decay data, by studying the sum rules for polarization operators momenta in charmonia in vector, pseudoscalar and axial channels. All of these determinations are in agreement and result in <(alpha_s/pi)G^2 > =0.005 \pm 0.004 GeV^4. Valence quark distributions in proton are calculated in QCD using the OPE in proton current virtuality. The quark distributions agree with those found from the deep inelastic scattering data. The same value of gluon condensate is favoured.

hep-ph↗
arXiv2004

Chiral phase transition in hadronic matter: the influence of baryon density

A qualitative analysis of the chiral phase transition in QCD with two massless quarks and non-zero baryon density is performed. It is assumed that at zero baryonic density, $ρ=0$, the temperature phase transition is of the second order and quark condesate $η=< 0\mid \bar{u} u\mid 0> =< 0 \mid \bar{d}d\mid 0>$ may be taken as order parameter of phase transition. The baryon masses strongly violate chiral symmetry, $m_B \sim < 0 \mid \bar{q}q\mid 0 >^{1/3}$. By supposing, that such specific dependence of baryon masses on quark condensate takes place up to phase transition point, it is shown, that at finite baryon density $ρ$ the phase transition becomes of the first order at the temperature $T=T_{\mathrm{ph}}(ρ)$ for $ρ>0$. At temperatures $T_{\mathrm{cont}}(ρ) > T > T_{\mathrm{ph}}(ρ)$ there is a mixed phase consisting of the quark phase (stable) and the hadron phase (unstable). At the temperature $T = T_{\mathrm{cont}}(ρ)$ the system experiences a continuous transition to the pure chirally symmetric phase.

hep-ph↗
arXiv2004

Chiral phase transition in hadronic matter at non-zero baryon density

A qualitative analysis of the chiral phase transition in QCD at non--zero baryon density is performed. It is assumed that at zero baryonic density, $ρ=0$, the temperature phase transition is of the second order and quark condesate $η= \mid < 0\mid \bar{u} u\mid 0> \mid =\mid< 0 \mid \bar{d}d\mid 0 >\mid $ may be taken as order parameter of phase transition. It is demonstrated, that the proportionality of baryon masses to quark condensate in the power 1/3, $m_B \sim \mid < 0 \mid {\bar q} q \mid 0 > \mid^{1/3}$ is valid in the wide interval of quark condensate values. By supposing, that such specific dependence of baryon masses on quark condensate takes place up to phase transition point, it is shown, that at finite baryon density $ρ$ the phase transition becomes of the first order at the temperature $T=T_{\mathrm{ph}}(ρ)$ for $ρ>0$. At temperatures $T_{\mathrm{cont}}(ρ) > T > T_{\mathrm{ph}}(ρ)$ there is a mixed phase consisting of the quark phase (stable) and the hadron phase (unstable). At the temperature $T = T_{\mathrm{cont}}(ρ)$ the system experiences a continuous transition to the pure chirally symmetric phase.

hep-ph↗
arXiv2004

The influence of baryons on the chiral phase transition in QCD

A qualitative analysis of the chiral phase transition in QCD with two massless quarks and non--zero baryon density is performed. It is assumed that at zero baryonic density, $ρ=0$, the temperature phase transition is of the second order. Due to a specific power dependence of baryon masses on the chiral condensate the phase transition becomes of the first order at the temperature $T=T_{\mathrm{ph}}(ρ)$ for $ρ>0$. At temperatures $T_{\mathrm{cont}}(ρ) > T > T_{\mathrm{ph}}(ρ)$ there is a mixed phase consisting of the quark phase (stable) and the hadron phase (unstable). At the temperature $T = T_{\mathrm{cont}}(ρ)$ the system experiences a continuous transition to the pure chirally symmetric phase.

hep-ph↗