arXiv subjects

A. Zhitnitsky

Publications and source records attributed to A. Zhitnitsky.

18 recordsLinked to original sources

arXiv2025

Search for anti-quark nuggets via their interaction with the LHC beam

Anti-quark nuggets (AQNs) have been suggested to solve the dark matter (DM) and the missing antimatter problem in the universe and have been proposed as an explanation of various observations. Their size is in the μm range and their density is about equal to the nuclear density with an expected flux of about $0.4 / km^2 / year$. For the typical velocity of DM constituents ($\sim$250 km/s), the solar system bodies act as highly performing gravitational lenses. Here we assume that DM streams or clusters are impinging, e.g., on the Earth, as it was worked out for DM axions and Weakly Interacting Massive Particles (WIMPs). Interestingly, in the LHC beam, unforeseen beam losses are triggered by so-called Unidentified Falling Objects (UFOs), which are believed to be constituted of dust particles with a size in the μm range and a density of several orders of magnitude lower than AQNs. Prezeau suggested that streaming DM constituents incident on the Earth should result in jet-like structures ("hairs") exiting the Earth, or a kind of caustics. Such ideas open novel directions in the search for DM. This work suggests a new analysis of the UFO results at the Large Hadron Collider (LHC), assuming that they are eventually, at least partly, due to AQNs. Firstly, a reanalysis of the existing data from the 4000 beam monitors since the beginning of the LHC is proposed, arguing that dust and AQNs should behave differently. The feasibility of this idea has been discussed with CERN accelerator people and potential collaborators.

hep-ex↗

arXiv2025

Daily modulations and broadband strategy in axion searches. An application with CAST-CAPP detector

It has been previously advocated that the presence of the daily and annual modulations of the axion flux on the Earth's surface may dramatically change the strategy of the axion searches. The arguments were based on the so-called Axion Quark Nugget (AQN) dark matter model which was originally put forward to explain the similarity of the dark and visible cosmological matter densities $Ω_{\rm dark}\sim Ω_{\rm visible}$. In this framework, the population of galactic axions with mass $ 10^{-6} {\rm eV}\lesssim m_a\lesssim 10^{-3}{\rm eV}$ and velocity $\langle v_a\rangle\sim 10^{-3} c$ will be accompanied by axions with typical velocities $\langle v_a\rangle\sim 0.6 c$ emitted by AQNs. Furthermore, in this framework, it has also been argued that the AQN-induced axion daily modulation (in contrast with the conventional WIMP paradigm) could be as large as $(10-20)\%$, which represents the main motivation for the present investigation. We argue that the daily modulations along with the broadband detection strategy can be very useful tools for the discovery of such relativistic axions. The data from the CAST-CAPP detector have been used following such arguments. Unfortunately, due to the dependence of the amplifier chain on temperature-dependent gain drifts and other factors, we could not conclusively show the presence or absence of a dark sector-originated daily modulation. However, this proof of principle analysis procedure can serve as a reference for future studies.

hep-ex↗

arXiv2025

Novel Dark Matter Signatures

Celestial observations often exhibit inexplicable planetary dependencies when the timing of an observable is projected onto planetary heliocentric positions. This is possible only for incident, non-relativistic streams. Notably, the celebrated dark matter (DM) in the Universe can form streams in our vicinity with speeds of about 240 km/s. Since gravitational impact scales with $1/(\text{velocity})^2$, all solar system objects, including the Sun and the Moon, act as strong gravitational lenses, with their focal planes located within the solar system. Even the Moon can focus penetrating particles toward the Earth at speeds of up to approximately 400 km/s, covering a large portion of the phase space of DM constituents. Consequently, the unexpected planetary dependencies of solar system observables may provide an alternative to Zwicky's tension regarding the overestimated visible cosmic mass. In this work, an overlooked but unexpected planetary dependency of any local observable serves as an analogue to Zwicky's cosmic measurements, particularly if a similar mysterious behavior has been previously noted. Thus, a persistent, unexpected planetary dependency represents a new tension between observation and expectation. The primary argument supporting DM in line with Zwicky's paradigm is this planetary dependency, which, on a local scale, constitutes the novel tension between observation and expectation. In particular, the recurrent planetary dependency of diverse observables mirrors Zwicky's cosmic tension with the overestimated visible mass. No other approach accounts for so many otherwise striking and mysterious observations in physics and medicine.

astro-ph.EP↗

arXiv2022

Probing Fundamental Physics With Multi-Modal Cosmic Ray Events

The Horizon-T experiment in Tien Shan is based on the idea of measuring the time at which EAS disc passes the observation level with nanosecond accuracy. The detector system consists of ten charged particles registration points located at distances of up to several hundred meters from each other. The points are equipped with detectors based on registration of Cherenkov radiation in glass and registration of scintillation light in polystyrene. The detectors register the arrival times of charged particles at the observation level with a resolution of ~2 ns, as required to study the spatial and temporal characteristics of the EAS and the structure of the multi-modal events specifically. Over the period of the Horizon-T data taking since 2017 to present, a large number of multi-modal events were detected. The data has presented numerous challenges that show the direction towards the further development of the detector system and of the analysis methods and techniques that could be applied to these multi-modal events.

hep-ex↗

arXiv2018

New mechanism producing axions in the AQN model and how the CAST can discover them

We advocate the idea that there is a fundamentally new mechanism for the axion production in the Sun, which has never been discussed previously in the literature. This novel mechanism of the axion production is based on the so-called Axion Quark Nugget (AQN) Dark Matter Model. These axions will be produced in addition to well studied axions emitted due to the Primakoff effect. The AQN model was originally invented as a natural explanation of the observed ratio $Ω_{\rm dark} \sim Ω_{\rm visible}$ when the DM and visible matter densities assume the same order of magnitude values, irrespectively to the axion mass $m_a$ or initial misalignment angle $θ_0$. This model, without adjustment of any parameters, reproduces reasonably the intensity of the extreme UV (EUV) radiation from the solar corona as a result of the AQN annihilation events with the solar material. This extra energy released in corona represents a resolution, within AQN framework, a long standing puzzle known in the literature as the "solar corona heating mystery". The same annihilation events also produce the relativistic axions. This represents a new mechanism of the axion production, and constitutes the main subject of this work. The flux of these axions is unambiguously fixed in this model and expressed in terms of the EUV luminosity from corona. We also compute the spectral properties of these axions and make few comments on the potentials for the discovery of these solar axions by the upgraded CAST (CERN Axion Solar Axion) experiment.

hep-ph↗

arXiv2007

Charge separation induced by P-odd bubbles in QCD matter

We examine the recent suggestion that P- and CP-odd effects in QCD matter can induce electric charge asymmetry with respect to reaction plane in relativistic heavy ion collisions. General arguments are given which confirm that the angular momentum of QCD matter in the presence of non-zero topological charge should induce an electric field aligned along the axis of the angular momentum. A simple formula relating the magnitude of charge asymmetry to the angular momentum and topological charge is derived. The expected asymmetry is amenable to experimental observation at RHIC and LHC; we discuss the recent preliminary STAR result in light of our findings.

hep-ph↗

arXiv2000

QCD-like Theories at Finite Baryon Density

We study QCD-like theories with pseudoreal fermions at finite baryon density. Such theories include two-color QCD with quarks in the fundamental representation of the color group as well as any-color QCD with quarks in the adjoint color representation. In all such theories the lightest baryons are diquarks. At zero chemical potential $μ$ they are, together with the pseudoscalar mesons, the Goldstone modes of a spontaneously broken enlarged chiral symmetry group. Using symmetry principles, we derive the low-energy effective Lagrangian for these particles. We find that a second order phase transition occurs at a value of $μ$ equal to half the mass of the Goldstone modes. For values of $μ$ beyond this point the scalar diquarks Bose condense and the diquark condensate is nonzero. We calculate the dependence of the chiral condensate, the diquark condensate, the baryon charge density, and the masses of the diquark and pseudoscalar excitations on $μ$ at finite bare quark mass and scalar diquark source. The relevance of our results to lattice QCD calculations and to real three-color QCD at finite baryon density is discussed.

hep-ph↗

arXiv2000

Induced theta-vacuum states in heavy ion collisions: a possible signature

It has been suggested recently that an arbitrary induced theta-vacuum state could be created in heavy ion collisions. If such a state can be created, it would decay by various mechanisms to the fundamental theta=0 state which is the true ground state of our world. In the following we will discuss the possibility of studying this unusual state through the emission of pions, eta-mesons, and eta'-mesons. We will also present the spectrum of the produced particles in this non-zero theta background. We use the instantaneous perturbation theory for our estimates.

hep-ph↗

arXiv2000

Can Induced Theta Vacua be Created in Heavy Ion Collisions?

The development of the early Universe is a remarkable laboratory for the study of most nontrivial properties of particle physics. What is more remarkable is the fact that these phenomena at the QCD scale can be, in principle, experimentally tested in heavy ion collisions. We expect that, in general, an arbitrary theta-state would be created in the heavy ion collisions, similar to the creation of the disoriented chiral condensate with an arbitrary isospin direction. It should be a large domain with a wrong $θ\neq 0$ orientation. We test this idea numerically in a simple model where we study the evolution of the phases of the chiral condensates in QCD with two quark flavors with non-zero theta-parameter. We see the formation of a non-zero theta-vacuum with the formation time of the order of $10^{-23}$ seconds. This result will have important implications for a possible axion search experiment at RHIC.

hep-ph↗

arXiv1999

Baryogenesis at the QCD Scale

We propose a new mechanism for explaining the observed asymmetry between matter and antimatter, based on nonperturbative physics at the QCD scale. Our mechanism is a charge separation scenario, making use of domain walls separating the recently discovered long-lived metastable vacua from the lowest energy vacuum. The walls acquire a fractional negative baryon charge, leaving behind a compensating positive baryon charge in the bulk. The regions of metastable vacuum bounded by walls ("B-shells") will contribute to the dark matter of the Universe.

hep-ph↗

arXiv1999

Baryogenesis with QCD Domain Walls

We propose a new baryosymmetric mechanism for baryogenesis which takes place at the QCD scale and is based on the existence of domain walls separating the metastable vacua from the lowest energy vacuum. The walls acquire fractional negative and positive baryon charges, while the observed baryon asymmetry is due to a non-zero value of the $ θ$ angle at the temperatures near the QCD chiral phase transition. The regions of metastable vacuum bounded by walls carry a negative baryon charge and may contribute a significant fraction of the dark matter of the Universe.

hep-ph↗

arXiv1998

Domain Walls and Theta Dependence in QCD with an Effective Lagrangian Approach

We suggest an anomalous effective Lagrangian which reproduces the anomalous conformal and chiral Ward identities and topological charge quantization in QCD. It is shown that the large N_c Di Vecchia-Veneziano-Witten effective chiral Lagrangian is locally recovered from our results, along with 1/N_c corrections, after integrating out the heavy "glueball" fields. All dimensionful parameters in our scheme are fixed in terms of the quark and gluon condensates and quark masses. We argue that for a certain range of parameters, metastable vacua appear which are separated from the true vacuum of lowest energy by domain walls. The surface tension of the wall is estimated, and the dynamics of the wall is discussed. The U(1) problem and the physics of the pseudo-goldstone bosons at different theta angles are addressed within the effective Lagrangian approach. Implications for axion physics, heavy ion collisions and the development of the early Universe during the QCD epoch are discussed.

hep-ph↗

arXiv1997

Condensates and Vacuum Structure of Adjoint QCD_2

We discuss a two dimensional SU(N) Yang-Mills theory coupled to massive adjoint fermions for different worlds classified by the integer k=0,1,...N-1. We study the fermion condensate for these unconnected worlds as a function of the parameter k. We show that the condensate as well as the spectrum of the theory do depend on this vacuum parameter k. Technically, the value of the fermion condensate is related to the value of the gluon condensate via the Operator Product Expansion. We use this to find the leading dependence (in the limit of a heavy quark) of the fermion condensate on the nontrivial vacuum angle k. We also determine the gluon condensate of the theory using low-energy theorems.

hep-ph↗

arXiv1996

Large Order Behavior of Quasiclassical Euclidean Gravity in Minisuperspace Models

We demonstrate in two minisuperspace models that a perturbation expansion of quasiclassical Euclidean gravity has a factorial dependence on the order of the term at large orders. This behavior indicates that the expansion is an asymptotic series which is suggestive of an effective field theory. The series may or may not be Borel summable depending on the classical solution expanded around. We assume that only the positive action classical solution contributes to path integrals. We close with some speculative discussion on possible implications of the asymptotic nature of the expansion.

hep-th↗

arXiv1994

The Pion Form Factor. Where Does It Come From?

We discuss the nonleading, ``soft" contribution to the pion form factor at intermediate momentum transfer within operator product expansion approach. We argue, that the corresponding contribution can temporarily {\bf simulate} the leading twist behavior in the extent region of $ Q^2:~~3 GeV^2\leq Q^2\leq 35 GeV^2 $, where $Q^2 F(Q^2)\sim const.$ Such a mechanism, if it is correct, would be an explanation of the phenomenological success of the dimensional counting rules (which theoretically correspond to the keeping of the asymptotically leading terms only) at available, very modest $Q^2$. The relation with quark model calculation is also discussed.

hep-ph↗

arXiv1994

The Nonperturbative Wave Functions, Transverse Momentum Distribution and QCD Vacuum Structure

It is shown that there is one-to-one correspondence between two, apparently different problems: \\ 1. The determination of the meanvalues of transverse moments $\la \vec{k}_{\perp}^{2n} \ra $ for the nonperturbative pion wave function $ψ(\k, x)$ and \\ 2. The evaluation of the mixed vacuum condensates $ \la \bar{q}G_{μν}^n q\ra $. eneral properties of the theory. We define and model $ψ(\k, x)$, satisfying all these constraints.

hep-ph↗

arXiv1992

Once more on $θ$-vacua in $2+1$ dimensional QED and 3+1 dimensional gluodynamics

Two different but tightly connected problems, $U(1)$ and strong CP violation problems, are discussed in two different models which exhibit both asymptotic freedom and confinement. One of them is the 3d Polyakov's model of compact QED and the other is 4d gluodynamics. It is shown that although both these models possess the long range interactions of the topological charges, only in the former case physics does not depend on $θ$; while the latter exhibits an explicit $θ$- dependence. The crucial difference is due to the observation, that the pseudoparticles of 4d gluodynamics possess an aditional quantum number, apart of the topological charge $Q$ .

hep-ph↗

arXiv1992

Quark confinement , topological susceptibility and all that in 4 dimensional gluodynamics

We discuss a few tightly connected problems, such as the $U(1)$ problem, confinement, the $θ$ -dependence within a framework of the dynamical toron approach. We calculate two fundamental characteristics of the theory: the vacuum expectation value (vev) of the Wilson loop and the topological susceptibility. The analogy with well known 2+1 dimensional QED which exhibits confinement phenomenon is also discussed.

hep-ph↗