arXiv subjects

I. Potashnikova

Publications and source records attributed to I. Potashnikova.

11 recordsLinked to original sources

arXiv2020

New high-sensitivity searches for neutrons converting into antineutrons and/or sterile neutrons at the European Spallation Source

The violation of Baryon Number, $\mathcal{B}$, is an essential ingredient for the preferential creation of matter over antimatter needed to account for the observed baryon asymmetry in the universe. However, such a process has yet to be experimentally observed. The HIBEAM/NNBAR %experiment program is a proposed two-stage experiment at the European Spallation Source (ESS) to search for baryon number violation. The program will include high-sensitivity searches for processes that violate baryon number by one or two units: free neutron-antineutron oscillation ($n\rightarrow \bar{n}$) via mixing, neutron-antineutron oscillation via regeneration from a sterile neutron state ($n\rightarrow [n',\bar{n}'] \rightarrow \bar{n}$), and neutron disappearance ($n\rightarrow n'$); the effective $Δ\mathcal{B}=0$ process of neutron regeneration ($n\rightarrow [n',\bar{n}'] \rightarrow n$) is also possible. The program can be used to discover and characterise mixing in the neutron, antineutron, and sterile neutron sectors. The experiment addresses topical open questions such as the origins of baryogenesis, the nature of dark matter, and is sensitive to scales of new physics substantially in excess of those available at colliders. A goal of the program is to open a discovery window to neutron conversion probabilities (sensitivities) by up to three orders of magnitude compared with previous searches. The opportunity to make such a leap in sensitivity tests should not be squandered. The experiment pulls together a diverse international team of physicists from the particle (collider and low energy) and nuclear physics communities, while also including specialists in neutronics and magnetics.

physics.ins-det↗

arXiv2020

A new parton model for the soft interactions at high energies: the Odderon

In this paper we discuss the Odderon contribution in our model[19] that gives a fairly good description of $σ_{\rm tot}$ $σ_{\rm el}$and $B_{\rm el}$ for proton-proton scattering. We show that the shadowing corrections are large, and induce considerable dependence on energy for the Odderon contribution, which in perturbative QCD does not depend on energy. This energy dependence is in agreement with the experimental data for $ρ= {\rm Re}/{\rm Im}$, assuming that the Odderon gives a contribution of about 1 mb at W = 7 TeV. This differs greatly with our estimates for a CGC based model. We reproduce the main features of the $ t$ -dependence that are measured experimentally: the slope of the elastic cross section at small $t$, the existence of the minima in $t$-dependence which is located at $|t|_{min}$ = 0.52 GeV 2 at W= 7 TeV; and the behaviour of the elastic cross section at $ |t| > |t|_{min}$.The real part of the elastic amplitude turns out to be much smaller than the experimental one. Consequently, to achieve a description of the data, it is necessary to add an odderon contribution.

hep-ph↗

arXiv2020

A new parton model for the soft interactions at high energies: two channel approximation

The primary goal of this paper is to describe the diffraction production using the model that takes into account the Pomeron interaction, and satisfies both $t$ and $s$ channel unitarity. We hope that these features will allow us to describe the diffraction production in a more convenient way than in CGC motivated models, that do not satisfy these unitarity constraints. Unfortunately, we show that both approaches are only able to describe half of the cross section for the single diffraction production, leaving the second half to be estimate of the large mass production in the Pomeron approach.The impact parameter dependance of the scattering amplitudes show that soft interactions at high energies measured at the LHC, have a much richer structure than presumed. We discuss the $t$-dependence of the elastic cross section in wide range of $|t|=0 ÷1 \,GeV^2 $. We show that in the kinemati region of the minimum, we cannot use approximate formulae to calculate the real part of the amplitude. The exact calculation in our model, shows that the real part is rather small, and it is necessary to include the Odderon contribution in order to describe the experimental data.

hep-ph↗

arXiv2018

A new parton model for the soft interactions at high energies

We propose a new parton model and demonstrate that the model describes the relevant experimental data at high energies. The model is based on Pomeron calculus in 1+1 space-time dimensions, as suggested in Ref. [18] and on simple assumptions regarding the hadron structure, related to the impact parameter dependence of the scattering amplitude. This parton model evolves from QCD, assuming that the unknown non-perturbative corrections lead to fixing size of the interacting dipoles. The advantage of this approach is that it satisfies both t-channel and s-channel unitarity, and can be used for summing all diagrams of Pomeron interactions, including Pomeron loops. We can use this approach for all reactions: dilute-dilute (hadron-hadron), dilute-dense (hadron-nucleus) and dense-dense (nucleus-nucleus)for the scattering of parton systems. Unfortunately, we are still far from being able to tackle this problem in the effective QCD theory at high energy (i.e. in the CGC /saturation approach).

hep-ph↗

arXiv2018

CGC/saturation approach: secondary Reggeons and $ρ={\rm Re/Im}$ dependence on energy

In this letter we demonstrate that a model which is based on the CGC/saturation approach, is able to describe soft interaction collisions for the wide range of $W=\sqrt{s} = 30 \,GeV ÷\, 13 \,TeV$ including the new TOTEM data at 13 TeV. We have incorporated the secondary Reggeons in our approach which enables us to describe the complete set of the soft data, including the energy behaviour of $ρ$ the ratio of the real to imaginary parts of the elastic scattering amplitude. We argue that it is premature to claim that an odderon contribution is necessary, but estimate its possible strength as $1 mb$ to the real part of the amplitude at W = 13 \,TeV. We show that the odderon contribution depends on the value of energy leading to ${\rm Re A\Lb s, t=0\Rb} $= 8 mb at W=21.2 \,GeV. Bearing this in mind we do not believe that $ρ$ at high energies is the appropriate observable for detecting the odderon contribution. The successful description of the soft data in the wide range of energy strengthens our claim that the CGC/saturation approach is the only viable candidate for an effective theory for high energy QCD.

hep-ph↗

arXiv2017

CGC/saturation approach: soft interaction at the LHC energies

In this paper we demonstrate that our model which is based on the CGC/saturation approach, is able to describe the soft interaction collisions including the new TOTEM prelimenary data at 13 TeV. We believe that this strengthens the argument that the CGC/saturation approach is the only viable candidate for an effective theory for high energy QCD.

hep-ph↗

arXiv2017

A CGC/saturation approach for angular correlations in proton-proton scattering

We generalized our model for the description of hard processes, and calculate the value of the azimuthal angle correlations ( Fourier harmonics $v_n$ ), for proton-proton scattering.The energy and multiplicity independence, as well as the value of $v_n$, turn out the be in accord with the experimental data, or slightly larger. Therefore, before making extreme assumptions on proton-proton collisions, such as the production of quark-gluon plasma in the large multiplicity events, we need to explain how these effect theBose-Einstein correlations which are so large, that have to be taken into account, and which are able to describe the angular correlations in proton-proton collisions, without including final state interactions

hep-ph↗

arXiv2012

N=4 SYM model for soft interactions at high energy

In this paper we compare the prediction for high energy soft interactions in the model of N=4 SYM, with the experimental data. It is shown that this model is able to describe the total, elastic and inelastic cross sections and the elastic slope with only three free parameters. However, the model failed to obtain the cross sections for diffractive production, which was close to the experimental data, giving small values for them. We believe that the theory of N=4 SYM, of the order of $1/λ$ is needed to find the origin of large mass diffraction.

hep-ph↗

arXiv2010

Inelastic processes in DIS and N=4 SYM

In this paper we compare the prediction for deep inelastic scattering from N=4 SYM with the HERA experimental data. The paper conveys two results. The first is the message that N=4 SYM is able to describe the DIS data with very good accuracy ($χ^2/d.o.f. \,\leq\,1.5$) in the region of $Q^2 = 0.85 ÷60\,GeV^2$ with $2/\sqrtλ = 0.7 ÷0.8 $ . The second is that the value of string coupling constant $g_s$ turns out to be so small that none of saturation effects will be visible in the region of accessible energies, including the maximal energy of the LHC (W = 14 \,\,TeV).

hep-ph↗

arXiv2009

Soft interaction at high energy and N=4 SYM

In this paper we show that the N=4 SYM total cross section violates the Froissart theorem, and in the huge range of energy this cross section is proportional to $s^{1/3}$. The graviton reggeization will change this increase to the normal logarithmic behaviour $σ\propto \ln^2 s$. However, we demonstrated that this happens at ultra high energy, much higher than the LHC energy. In the region of accessible energy we need to assume that there is a different source for the total cross section, with the value of the cross section about 40 mb. With this assumption we successfully describe $σ_{tot}, σ_{el}$ and $σ_{diff}$ for the accessible range of energy from the fixed target Fermilab to the Tevatron energies. It turns out that the N=4 SYM mechanism can be responsible only for a small part of the inelastic cross section for this energy region (about $2 mb$). However, at the LHC energy the N=4 SYM theory can describe the multipartticle production with $σ_{in} \approx 28 mb$. The second surprise is the fact that the total cross section and the diffraction cross section can increase considerably from the Tevatron to the LHC energy. The bad description of $B_{el}$ gives the strong argument that the non N=4 SYM background should depend on energy. We believe that we have a dilemma: to find a new mechanism for the inelastic production in the framework of N=4 SYM other than the reggeized graviton interaction, or to accept that N=4 SYM is irrelevant to any experimental data that has been measured before the LHC era.

hep-ph↗

arXiv2007

Observation of a resonance in the K$_s$p decay channel at a mass of 1765 MeV/c$^2$

We report on the observation of a K$_s$p resonance signal at a mass of 1765$\pm$5 MeV/c$^2$, with intrinsic width $Γ= 108\pm 22$ MeV/c$^2$, produced inclusively in $Σ^-$-nucleus interactions at 340 GeV/c in the hyperon beam experiment WA89 at CERN. The signal was observed in the kinematic region $x_F>0.7$, in this region its production cross section rises approximately linearly with $(1-x_F)$, reaching $BR(X\to K_S p)\cdot dσ/dx_F = (5.2\pm 2.3) μb $ per nucleon at $x_F=0.8$. The hard \xf spectrum suggests the presence of a strong leading particle effect in the production and hence the identification as a $Σ^{*+}$ state. No corresponding peaks were observed in the $K^- p$ and $Λπ^{\pm}$ mass spectra.

hep-ex↗