arXiv subjects

Maxim Yu. Khlopov

Publications and source records attributed to Maxim Yu. Khlopov.

At least 55 records · Page 3Linked to original sources

arXiv2015

Neural Networks Search for Charged Higgs Boson of Two Doublet Higgs Model at the Hadrons Colliders

In this work, we present an analysis of a search for charged Higgs boson in the context of Two Doublet Higgs Model (2HDM) which is an extension of the Standard Model of particles physics. The 2HDM predicts by existence scalar sector with new five Higgs bosons, two of them are electrically charged and the other three Higgs bosons are neutral charged. Our analysis based on the Monte Carlo data produced from the simulation of 2HDM with proton antiproton collisions at the Tevatron $\sqrt{s}=1.96$ TeV (Fermi Lab) and proton proton collisions at the LHC $\sqrt{s}=14$ TeV (CERN) with final state includes electron , muon , multiple jets and missing transverse energy via the production and decay of the new Higgs in the hard process $pp(\bar{p})\rightarrow t\bar{t}\rightarrow H^{+}b H^{-}\bar{b}$

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arXiv2015

Phenomenology of Hidden Abelian Higgs Model at Hadron Colliders using Neural Networks and Monte Carlo Techniques (Gauge Sector $Z_{HAHM}$ & Scalar Sector H)

The Hidden Abelian Higgs Model (HAHM) is an extension of the Standard Model based on the gauge group $G =SU(3)_{C} \times SU(2)_{L} \times U(1)_{Y} \times U(1)_{X}$ i.e. an extra $U(1)_{X}$ gauge group in addition to the SM gauge groups.In HAHM, an Abelian Hidden sector is coupled to the SM, and the resulting new Higgs boson H and new neutral gauge boson $Z_{HAHM}$ fields are allowed to mix with the corresponding SM fields. In this work, we search for the new neutral gauge boson $Z_{HAHM}$ and new Higgs boson in the context of the Hidden Abelian Higgs Model (HAHM) through the decay process $pp(\bar{p})\rightarrow H\rightarrow Z_{HAHM}Z_{HAHM}\rightarrow \textit{l}^{\pm}\textit{l}^{\mp}\textit{l}^{\pm}\textit{l}^{\mp},(\textit{l}=e,μ)$ with 4 charged leptons in the final state in the mass range $200\leq Z_{HAHM} \leq 700$ GeV and the production and decay of new Higgs boson with 2 charged leptons in the final state of the process $pp(\bar{p})\rightarrow H\rightarrow\textit{l}^{\pm}\textit{l}^{\mp}jj ,(\textit{l}=e,μ)$ with jets or final state of the proces $pp(\bar{p})\rightarrow H\rightarrow \textit{l}^{\pm}\textit{l}^{mp}ν\barν,(l=e,μ)$ with missing energy.We used Monte Carlo data produced from proton-proton collisions at the LHC CERN (CMS and ATLAS detectors) for different center of mass energies up to $\sqrt{s}= 14 TeV$

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arXiv2014

Introduction to the special issue of Modern Physics Letters A "Indirect dark matter searches"

The nature of cosmological dark matter finds its explanation in physics beyond the Standard model of elementary particles. The landscape of dark matter candidates contains a wide variety of species, either elusive or hardly detectable in direct experimental searches. Even in case, when such searches are possible the interpretation of their results implies additional sources of information, which provide indirect effects of dark matter. Some nontrivial probes for the nature of the dark matter are presented in the present issue.

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arXiv2014

Effects of dark atom excitations

New stable quarks and charged leptons may exist and be hidden from detection, as they are bound by Coulomb interaction in neutral dark atoms of composite dark matter. This possibility leads to fundamentally new types of indirect effects related to the excitation of such dark atoms followed by their electromagnetic de-excitation. Stable -2 charged particles, bound to primordial helium in O-helium (OHe) atoms, represent the simplest model of dark atoms. Here we consider the structure of OHe atomic levels which is a necessary input for the indirect tests of such composite dark matter scenarios, and we give the spectrum of electromagnetic transitions from the levels excited in OHe collisions.

astro-ph.HE↗

arXiv2014

Search for New Charged Gauge Boson $W'$ via Phenomenology of the Left-Right Symmetric Model at Hadron Colliders

In this article, a search for signatures of the hypothetical new heavy charged gauge boson $W'$ in proton-proton collisions at the Large Hadron Collider (LHC) with center-of-mass energy range from 6 to 14 TeV and in proton-antiproton collisions at the Fermilab Tevatron Collider with center-of-mass energy of 1.96 TeV. The production of $W'$ and its decay were simulated via the decay channel to top and anti-bottom by using Monte Carlo events generator programs. The events were simulated according to the extension of Standard Model (SM) and the Left-Right symmetry Model (LRSM) based on the gauge symmetry group SU(3)C x SU(2)L x SU(2)R x U(1)B-L. The LRSM model exhibits signatures of new physics Beyond the Standard Model (BSM) at the hadron colliders. The most interesting arising from the LRSM is the production and decay of new boson $W'$. We present analysis of detecting the signal of $W'$ bosons using the process $pp(\bar{p})\rightarrow W'\rightarrow t\bar{b}\rightarrow \ellνb\bar{b} )$ in final state with (electrons or muons) and missing transverse energy. The production of $W'$ boson was found at the LHC at center of mass energy 10 TeV with mass 1TeV and the production cross section of 13.31pb.

hep-ph↗

arXiv2014

Dark atoms and the positron-annihilation-line excess in the galactic bulge

It was recently proposed that stable particles of charge $-2$, $O^{--}$, can exist and constitute dark matter after they bind with primordial helium in O-helium (OHe) atoms. We study here in details the possibility that this model provides an explanation for the excess of gamma radiation in the positron-annihilation line from the galactic bulge observed by INTEGRAL. This explanation assumes that OHe, excited to a 2s state through collisions in the central part of the Galaxy, de-excites to its ground state via an E0 transition, emitting an electron-positron pair. The cross section for OHe collisions with excitation to 2s level is calculated and it is shown that the rate of such excitations in the galactic bulge strongly depends not only on the mass of O-helium, which is determined by the mass of $O^{--}$, but also on the density and velocity distribution of dark matter. Given the astrophysical uncertainties on these distributions, this mechanism constrains the $O^{--}$ mass to lie in two possible regions. One of these is reachable in the experimental searches for stable multicharged particles at the LHC.

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arXiv2013

Fundamental Particle Structure in the Cosmological Dark Matter

The nonbaryonic dark matter of the Universe is assumed to consist of new stable forms of matter. Their stability reflects symmetry of micro world and mechanisms of its symmetry breaking. Particle candidates for cosmological dark matter are lightest particles that bear new conserved quantum numbers. Dark matter particles may represent ideal gas of non-interacting particles. Self-interacting dark matter weakly or superweakly coupled to ordinary matter is also possible, reflecting nontrivial pattern of particle symmetry in the hidden sector of particle theory. In the early Universe the structure of particle symmetry breaking gives rise to cosmological phase transitions, from which macroscopic cosmological defects or primordial nonlinear structures can be originated. Primordial black holes (PBHs) can be not only a candidate for dark matter, but also represent a universal probe for super-high energy physics in the early Universe. Evaporating PBHs turn to be a source of even superweakly interacting particles, while clouds of massive PBHs can serve as a nonlinear seeds for galaxy formation. The observed broken symmetry of the three known families may provide a simultaneous solution for the problems of the mass of neutrino and strong CP violation in the unique framework of models of horizontal unification. The existence of new stable charged leptons and quarks is possible, hidden in elusive "dark atoms". Such possibility, strongly restricted by the constraints on anomalous isotopes of light elements, is not excluded in scenarios that predict stable double charged particles. The excessive -2 charged particles are bound in these scenarios with primordial helium in O-helium "atoms", maintaining specific nuclear-interacting form of the dark matter, which may provide an interesting solution for the puzzles of the direct dark matter searches. (abridged)

astro-ph.CO↗

arXiv2013

On the problem of quark-lepton families

The problem of quark-lepton families is discussed in the "bottom-up" phenomenological approach to the extensions of the Standard model. It provides the possibility of the {\it Horizontal unification} of the three known families on the basis of horizontal gauge flavor $SU(3)_H$ symmetry. The new generations of quarks and leptons can exist. If unstable and mixed with light fermions, they should contribute the CKM matrix. If stable and decoupled from known families, new generations can provide new candidates for dark matter.

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arXiv2012

Virtual Institute of Astroparticle physics - science and education online

Virtual Institute of Astroparticle Physics (VIA), integrated in the structure of Laboratory of AstroParticle physics and Cosmology (APC) is evolved in a unique multi-functional complex of $e-science$ and $e-learning$, supporting at distance interactive online participation in conferences and meetings, various forms of collaborative scientific work as well as programs of education. The activity of VIA takes place on its website and includes regular videoconferences with systematic basic courses and lectures on various issues of astroparticle physics, regular online transmission of APC Colloquiums, participation at distance in various scientific meetings and conferences, library of their records and presentations, a multilingual Forum. VIA virtual rooms are open for meetings of scientific groups and for individual work of supervisors with their students. The format of a VIA videoconferences was effectively used in the program of XV Bled Workshop to provide a world-wide participation at distance in discussion of the open questions of physics beyond the standard model. The VIA system has demonstrated its high quality and stability even for minimal equipment (laptop with microphone and webcam and WiFi Internet connection) and without any technical assistance at place.

physics.gen-ph↗

arXiv2011

Physics of Dark Matter in the Light of Dark Atoms

Direct searches for dark matter lead to serious problems for simple models with stable neutral Weakly Interacting Massive Particles (WIMPs) as candidates for dark matter. A possibility is discussed that new stable quarks and charged leptons exist and are hidden from detection, being bound in neutral dark atoms of composite dark matter. Stable -2 charged particles $O^{--}$ are bound with primordial helium in O-helium (OHe) atoms, being specific nuclear interacting form of composite Warmer than Cold dark matter. Slowed down in the terrestrial matter, OHe is elusive for direct methods of underground dark matter detection based on the search for effects of nuclear recoil in WIMP-nucleus collisions. The positive results of DAMA experiments can be explained as annual modulation of radiative capture of O-helium by nuclei. In the framework of this approach test of DAMA results in detectors with other chemical content becomes a nontrivial task, while the experimental search of stable charged particles at LHC or in cosmic rays acquires a meaning of direct test for composite dark matter scenario.

astro-ph.CO↗

arXiv2011

VIA Discussions at XIV Bled Workshop

Virtual Institute of Astroparticle Physics (VIA), integrated in the structure of Laboratory of AstroParticle physics and Cosmology (APC) is evolved in a unique multi-functional complex of $e-science$ and $e-learning$, supporting various forms of collaborative scientific work as well as programs of education at distance. The activity of VIA takes place on its website and includes regular videoconferences with systematic basic courses and lectures on various issues of astroparticle physics, regular online transmission of APC Colloquiums, participation at distance in various scientific meetings and conferences, library of their records and presentations, a multilingual Forum. VIA virtual rooms are open for meetings of scientific groups and for individual work of supervisors with their students. The format of a VIA videoconferences was effectively used in the program of XIV Bled Workshop to provide a world-wide participation at distance in discussion of the open questions of physics beyond the standard model. The VIA system has demonstrated its high quality and stability even for minimal equipment (laptop with microphone and webcam and WiFi Internet connection).

astro-ph.IM↗

arXiv2011

Towards Nuclear Physics of OHe Dark Matter

The nonbaryonic dark matter of the Universe can consist of new stable charged particles, bound in heavy "atoms" by ordinary Coulomb interaction. If stable particles $O^{--}$ with charge -2 are in excess over their antiparticles (with charge +2), the primordial helium, formed in Big Bang Nucleosynthesis, captures all $O^{--}$ in neutral "atoms" of O-helium (OHe). Interaction with nuclei plays crucial role in the cosmological evolution of OHe and in the effects of these dark atoms as nuclear interacting dark matter. Slowed down in terrestrial matter OHe atoms cause negligible effects of nuclear recoil in underground detectors, but can experience radiative capture by nuclei. Local concentration of OHe in the matter of detectors is rapidly adjusted to the incoming flux of cosmic OHe and possess annual modulation due to Earth's orbital motion around the Sun. The potential of OHe-nucleus interaction is determined by polarization of OHe by the Coulomb and nuclear force of the approaching nucleus. Stark-like effect by the Coulomb force of nucleus makes this potential attractive at larger distances, while change of polarization by the effect of nuclear force gives rise to a potential barrier, preventing merging of nucleus with helium shell of OHe atom. The existence of the corresponding shallow well beyond the nucleus can provide the conditions, at which nuclei in the matter of DAMA/NaI and DAMA/LIBRA detectors have a few keV binding energy with OHe, corresponding to a level in this well. Annual modulation of the radiative capture rate to this level can reproduce DAMA results. The OHe hypothesis can qualitatively explain the controversy in the results of direct dark matter searches by specifics of OHe nuclear interaction with the matter of underground detectors.

hep-ph↗

arXiv2011

Accelerator probes for new stable quarks

The nonbaryonic dark matter of the Universe can consist of new stable double charged particles $O^{--}$, bound with primordial helium in heavy neutral O-helium (OHe)"atoms" by ordinary Coulomb interaction. O-helium dark atoms can play the role of specific nuclear interacting dark matter and provide solution for the puzzles of dark matter searches. The successful development of composite dark matter scenarios appeals to experimental search for the charged constituents of dark atoms. If $O^{--}$ is a "heavy quark cluster" $\bar U \bar U \bar U$, its production at accelerators is virtually impossible and the strategy of heavy quark search is reduced to search for heavy stable hadrons, containing only single heavy quark (or antiquark). Estimates of production cross section of such particles at LHC are presented and the experimental signatures for new stable quarks are outlined.

hep-ex↗

arXiv2011

Dark Atoms of Dark Matter and their Stable Charged Constituents

Direct searches for dark matter lead to serious problems for simple models with stable neutral Weakly Interacting Massive Particles (WIMPs) as candidates for dark matter. A possibility is discussed that new stable quarks and charged leptons exist and are hidden from detection, being bound in neutral dark atoms of composite dark matter. Stable -2 charged particles $O^{--}$ are bound with primordial helium in O-helium (OHe) atoms, being specific nuclear interacting form of composite dark matter. The positive results of DAMA experiments can be explained as annual modulation of radiative capture of O-helium by nuclei. In the framework of this approach test of DAMA results in detectors with other chemical content becomes a nontrivial task, while the experimental search of stable charged particles at LHC or in cosmic rays acquires a meaning of direct test for composite dark matter scenario.

astro-ph.CO↗

arXiv2010

Dark Atoms of Dark Matter from New Stable Quarks and Leptons

The nonbaryonic dark matter of the Universe can consist of new stable charged leptons and quarks, if they are hidden in elusive "dark atoms" of composite dark matter. Such possibility can be compatible with the severe constraints on anomalous isotopes, if there exist stable particles with charge -2 and there are no stable particles with charges +1 and -1. These conditions cannot be realized in supersymmetric models, but can be satisfied in several recently developed alternative scenarios. The excessive -2 charged particles are bound with primordial helium in O-helium "atoms", maintaining specific nuclear-interacting form of the Warmer than Cold Dark Matter. The puzzles of direct dark matter searches appear in this case as a reflection of nontrivial nuclear physics of O-helium.

astro-ph.CO↗

arXiv2010

The dark atoms of dark matter

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arXiv2010

Dark Atoms of the Universe: towards OHe nuclear physics

The nonbaryonic dark matter of the Universe is assumed to consist of new stable particles. A specific case is possible, when new stable particles bear ordinary electric charge and bind in heavy "atoms" by ordinary Coulomb interaction. Such possibility is severely restricted by the constraints on anomalous isotopes of light elements that form positively charged heavy species with ordinary electrons. The trouble is avoided, if stable particles $X^{--}$ with charge -2 are in excess over their antiparticles (with charge +2) and there are no stable particles with charges +1 and -1. Then primordial helium, formed in Big Bang Nucleosynthesis, captures all $X^{--}$ in neutral "atoms" of O-helium (OHe). Schrodinger equation for system of nucleus and OHe is considered and reduced to an equation of relative motion in a spherically symmetrical potential, formed by the Yukawa tail of nuclear scalar isoscalar attraction potential, acting on He beyond the nucleus, and dipole Coulomb repulsion between the nucleus and OHe at small distances between nuclear surfaces of He and nucleus. The values of coupling strength and mass of $σ$-meson, mediating scalar isoscalar nuclear potential, are rather uncertain. Within these uncertainties and in the approximation of rectangular potential wells and wall we find a range of these parameters, at which the sodium nuclei have a few keV binding energy with OHe. The result also strongly depend on the precise value of parameter $d_o$ that determines the size of nuclei. At nuclear parameters, reproducing DAMA results, OHe-nucleus bound states can exist only for intermediate nuclei, thus excluding direct comparison with these results in detectors, containing very light (e.g. $^3He$) and heavy nuclei (like Xe).

astro-ph.CO↗

arXiv2010

Puzzles of Dark Matter - More Light on Dark Atoms?

Positive results of dark matter searches in experiments DAMA/NaI and DAMA/LIBRA confronted with results of other groups can imply nontrivial particle physics solutions for cosmological dark matter. Stable particles with charge -2, bound with primordial helium in O-helium "atoms" (OHe), represent a specific nuclear-interacting form of dark matter. Slowed down in the terrestrial matter, OHe is elusive for direct methods of underground Dark matter detection using its nuclear recoil. However, low energy binding of OHe with sodium nuclei can lead to annual variations of energy release from OHe radiative capture in the interval of energy 2-4 keV in DAMA/NaI and DAMA/LIBRA experiments. At nuclear parameters, reproducing DAMA results, the energy release predicted for detectors with chemical content other than NaI differ in the most cases from the one in DAMA detector. Moreover there is no bound systems of OHe with light and heavy nuclei, so that there is no radiative capture of OHe in detectors with xenon or helium content. Due to dipole Coulomb barrier, transitions to more energetic levels of Na+OHe system with much higher energy release are suppressed in the correspondence with the results of DAMA experiments. The proposed explanation inevitably leads to prediction of abundance of anomalous Na, corresponding to the signal, observed by DAMA.

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