Alexei L. Semenov

Russian Academy of Sciences | RAS · Divisions of Cybernetics

A. Введение Теория определимости-это часть математической логики, занимающаяся проблемами определения понятий, в частности одного понятия через другие. Понятие определения относится к числу столь же базовых понятий математической логики и теоретической информатики, математики и существования человека, как и понятия: доказательства, вычисления, слож...

We present a direct observation of the geometrical jitter in single photon detection by a straight superconducting nanowire. Differential measurement technique was applied to the 180-μm long nanowire similar to those commonly used in the technology of superconducting nanowire single photon detectors (SNSPD). A non-gaussian geometrical jitter appear...

We report onthe energy relaxation of electrons studied by means of magnetoconductance and photoresponse in a series of superconducting NbN film with thickness in the range from 3 to 33 nm. The inelastic scattering rate of electrons on phonons obeys Tntemperature dependence where the exponent is in the range ????≈3.2÷3.8and shows no systematically d...

1. Our main result is the proof of Kontsevich Conjecture on the existence of a natural isomorphism between the automorphism group of the Weyl algebra (the algebra of polynomial differential operators) and the group of polynomial symplectomorphisms of the affine space of corresponding dimension. The proof by A.Ya. Belov and A.M. Elishev and Jie Tai...

VEPP-5 Injection Complex (IC) is designed to supply BINP RAS colliders with high energy electron and positron beams. Recently constructed K-500 beam transfer line connects IC to both VEPP-4M and VEPP-2000 colliders. IC two collider operation was successfully performed in 2016. Nowadays, research on improvement of IC productivity is carried out, in...

With use of the travelling-wave geometry approach, integrated superconductor-nanophotonic devices based on silicon nitride nanophotonic waveguide with a superconducting NbN-nanowire suited on top of the waveguide were fabricated. NbN-nanowire was operated as a single-photon counting detector with up to 92 % on-chip detection efficiency in the coher...

Семенов Алексей Львович - доктор физико-математических наук, профессор МГУ, академик, директор Института образовательной информатики ФИЦ «Информатика и управление» РАН. Адрес: 119333, Москва, ул. Вавилова, 40. E-mail: alsemenov@ccas.ruСимор Паперт — крупнейший философ образования и выдающийся педагог современности, основоположник конструкционизма —...

Two BINP colliders VEPP-4M and VEPP-2000 e+e-colliders are under operation with the beams feeding from VEPP-5 Injection Complex via newly constructed K-500 beam transfer line. Upgraded injection chain demonstrated ability to provide designed luminosity both to VEPP-4M and VEPP-2000 and techniques of reliable operation are under development now. The...

Using amplitude-modulated absorption of sub-THz radiation (AMAR) method, we studied electron-phonon relaxation in thin disordered films of tungsten silicide. We found a response time ~ 800 ps at critical temperature Tc = 3.4 K, which scales as minus 3 in the temperature range from 1.8 to 3.4 K. We discuss mechanisms, which can result in a strong ph...

We present ultra-wideband zero-bias Schottky diode detector modules with monolithically integrated log-spiral antenna. Detectors exhibit a broad-band response with a stronger roll-off above 800 GHz and the minimum noise-equivalent power of 10 pW/√Hz. The intrinsic diode response time to a short THz radiation has been measured to be less than 25ps.

We report a study of the relaxation time of the restoration of the resistive superconducting state in single crystalline boron-doped diamond using amplitude-modulated absorption of (sub-)THz radiation (AMAR). The films grown on an insulating diamond substrate have a low carrier density of about 2.5×1021cm−3 and a critical temperature of about 2K. B...

The Svenonius theorem describes the (first-order) definability in a structure in terms of permutations preserving the relations of elementary extensions of the structure. In the present article, we prove a version of this theorem using permutations of sequences over the original structure (these are permutations of sequences of tuples of the struct...

In the present paper we discuss the lattice of reducts of $<\mathbb{Q}, \{$+$\}>$

The paper presents recent results and open problems on classes of definable relations (definability spaces, reducts, relational algebras) as well as sources for the research starting from the XIX century. Finiteness conditions are investigated, including quantifier alternation depth and number of arguments width. The infinite lattice of definabilit...

We report measurements of the inclusive transverse momentum (p(T)) distribution of centrally produced K-S(0), K-*perpendicular to (892), and phi(0)(1020) mesons up to p(T) = 10 GeV/c in minimum bias events, and K-S(0) and Lambda(0) particles up to p(T) = 20 GeV/c in jets with transverse energy between 25 and 160 GeV in p (p) over bar collisions. Th...

We report a measurement of the differential cross section, d\sigma/d(cos \thetat), for top-quark-pair production as a function of the top-quark production angle in proton-antiproton collisions at sqrts = 1.96 TeV. This measurement is performed using data collected with the CDF II detector at the Tevatron, corresponding to an integrated luminosity o...

We report on a search for a dijet resonance in events with only two or three jets and large imbalance in the total event transverse momentum. This search is sensitive to the possible production of a new particle in association with a $W$ or $Z$ boson, where the boson decays leptonically with one or more neutrinos in the final state. We use the full...

Using the full CDF Run II data sample, we report evidence for a new resonance, which we refer to as B(5970), found simultaneously in the $B^0\pi^+$ and $B^+\pi^-$ mass distributions with a significance of 4.4 standard deviations. We further report the first study of resonances consistent with orbitally excited $B^{+}$ mesons and an updated measurem...

We measure the time dependence of the ratio of decay rates for D0 -> K+ pi- to the Cabibbo-favored decay D0 -> K- pi+. The charge conjugate decays are included. A signal of 3.3 x 10^4 D*+ -> pi+ D0, D0 -> K+ pi- decays is obtained with D0 proper decay times between 0.75 and 10 mean D0 lifetimes. The data were recorded with the CDF II detector at th...

A method for directly detecting edges in images which are obtained with a passive stand-off terahertz (THz) imaging system is presented. This novel method can improve the signal-to-noise ratio of THz images as well as it may contribute to solving the privacy problem of body scanners. In addition the proposed method when used with a suitable Spatial...

We present ultra-wideband zero-bias Schottky diode detector modules with monolithically integrated log-spiral antenna. Detectors exhibit a broad-band response with a stronger roll-off above 800 GHz and the minimum noise-equivalent power of 10 pW/√Hz. The intrinsic diode response time to a short THz radiation has been measured to be less than 25ps.

We present a measurement of the total decay width of the top quark using events with top-antitop-quark pair candidates reconstructed in the final state with one charged lepton and four or more hadronic jets. We use the full Tevatron Run II data set of $\sqrt{s} = 1.96$ TeV proton-antiproton collisions recorded by the CDF II detector. The top-quark...

Using data from proton-antiproton collisions at Ecms=1.96 TeV recorded by the CDF II detector at the Fermilab Tevatron, evidence for the excited resonance state Lambda_b* is presented in its Lambda_b0 pi+ pi- decay, followed by the Lambda_b0 -->Lambda_c+ (-->proton K- pi+) pi- decays. The analysis is based on a data sample corresponding to an integ...

We measure the asymmetry in the charge-weighted rapidity of the lepton in semileptonic ttbar decays recorded with the CDF II detector using the full Tevatron Run II sample, corresponding to an integrated luminosity of 9.4/fb. A parametrization of the asymmetry as a function of the charge-weighted rapidity is used to correct for the finite acceptanc...

The electronic system developed for the SpaCal lead/scintillating-fibre calorimeters of the H1 detector in operation at the HERA ep collider is described in detail and the performance achieved during H1 data-taking is presented. The 10 MHz bunch crossing rate of HERA puts severe constraints on the requirements of the electronics. The energy and tim...

We summarize and combine direct measurements of the mass of the $W$ boson in $\sqrt{s} = 1.96 \text{TeV}$ proton-antiproton collision data collected by CDF and D0 experiments at the Fermilab Tevatron Collider. Earlier measurements from CDF and D0 are combined with the two latest, more precise measurements: a CDF measurement in the electron and muon...

We present a search for the pair production of a narrow nonstandard-model strongly interacting particle that decays to a pair of quarks or gluons, leading to a final state with four hadronic jets. We consider both nonresonant production via an intermediate gluon as well as resonant production via a distinct nonstandard-model intermediate strongly i...

Using scanning tunneling spectroscopy, we address the problem of the superconductor-insulator phase transition in homogeneously disordered ultrathin (2–15 nm) films of NbN. Samples thicker than 8 nm, for which the Ioffe-Regel parameter kFl≥5.6, manifest a conventional superconductivity: a spatially homogeneous BCS-like gap, vanishing at the critica...

Drell-Yan lepton pairs are produced in the process p̄p→e e+X through an intermediate γ/Z boson. The lepton angular distributions are used to provide information on the electroweak-mixing parameter sinθw via its observable effective-leptonic sinθw, or 2θefflept. A new method to infer sin θw or, equivalently, the W-boson mass M in the on-shell scheme...

We present the first signature-based search for delayed photons using an exclusive photon plus missing transverse energy final state. Events are reconstructed in a data sample from the CDF II detector corresponding to $6.3 \text{fb}^{-1}$ of integrated luminosity from $\sqrt{s}=1.96$ TeV proton-antiproton collisions. Candidate events are selected i...

In this paper, we present our approaches to the development of fiber-coupled superconducting single photon detectors with enhanced photon absorption. For such devices we have measured detection efficiency in wavelength range from 500 to 2000 nm. The best fiber coupled devices exhibit detection efficiency of 44.5% at 1310 nm wavelength and 35.5% at...

We investigate the improvement of detection efficiency by a spiral layout of a Superconducting Nanowire Single-Photon Detector (SNSPD). The design is less susceptible to the critical current reduction due to turns in the nanowire than the classical meander design. Detector samples with different nanowire width from 300 to 100 nm are structured from...

High-temperature superconducting YBa2Cu3O7-d (YBCO) thin-film detectors with improved responsivities were developed for fast time-domain measurements in the THz frequency range. YBCO thin films of ≈ 30 nm thickness were patterned to micro- and nanobridges and embedded into planar log-spiral THz antennas. The YBCO thin-film detectors were characteri...

We present systematic measurements of the temperature-dependence of detection efficiencies in TaN and NbN superconducting nanowire single-photon detectors. We have observed a clear increase of the cut-off wavelength with decreasing temperature that we can qualitatively describe by a temperaturedependent diffusion coefficient of the quasi-particles...

We present a search for a standard model Higgs boson decaying to two $W$ bosons that decay to leptons using the full data set collected with the CDF II detector in $\sqrt{s}=1.96$ TeV $p\bar{p}$ collisions at the Fermilab Tevatron, corresponding to an integrated luminosity of 9.7 fb${}^{-1}$. We obtain no evidence for production of a standard model...

We demonstrate evidence of coherent magnetic flux tunneling through superconducting nanowires patterned in a thin highly disordered NbN film. The phenomenon is revealed as a superposition of flux states in a superconducting loop with the nanowire acting as an effective tunnel barrier for the magnetic flux, and reproducibly observed in different wir...

We present a search for chargino-neutralino associated production using like electric charge dilepton events collected by the CDF II detector at the Fermilab Tevatron in proton-antiproton collisions at sqrt[s]=1.96 TeV. One lepton is identified as the hadronic decay of a tau lepton, while the other is an electron or muon. In data corresponding to 6...

We present a measurement of the top-quark mass using the full data set of Tevatron $\sqrt{s} = 1.96$ TeV proton-antiproton collisions recorded by the CDF II detector, corresponding to an integrated luminosity of \invfb{8.7}. The analysis uses events with one semileptonic $t$ or $\bar{t}$ decay, but without detection of the electron or muon. We sele...

The primary motivation of the GlueX experiment is to search for and ultimately study the pattern of gluonic excitations in the meson spectrum produced in $\gamma p$ collisions. Recent lattice QCD calculations predict a rich spectrum of hybrid mesons that have both exotic and non-exotic $J^{PC}$, corresponding to $q\bar{q}$ states ($q=u,$ $d,$ or $s...

micrOMEGAs is a code to compute dark matter observables in generic extensions of the standard model. This new version of micrOMEGAs is a major update which includes a generalization of the Boltzmann equations to accommodate models with asymmetric dark matter or with semi-annihilation and a first approach to a generalization of the thermodynamics of...

We present a measurement of the top-quark pair production cross section in proton-antiproton collisions at √s=1.96 TeV. The data were collected at the Fermilab Tevatron by the CDF II detector and correspond to an integrated luminosity of 8.8 fb1, representing the complete CDF Run II data set. We select events consistent with the production of top-q...

We report on a measurement of the top-quark electric charge in ttbar events in which one W boson originating from the top-quark pair decays into leptons and the other into hadrons. The event sample was collected by the CDF II detector in sqrt(s)=1.96 TeV proton-antiproton collisions and corresponds to 5.6 fb^(-1). We find the data to be consistent...

We report on a search for Bs0→μμ and B0→μμ decays using proton-antiproton collision data at √s=1.96 TeV corresponding to 10 fb1 of integrated luminosity collected by the CDF II detector at the Fermilab Tevatron collider. The observed number of B0 candidates is consistent with background-only expectations and yields an upper limit on the branching f...

We report on a measurement of the cross section for direct-photon production in association with a heavy quark using the full data set of √s=1.96 TeV proton-antiproton collisions corresponding to 9.1 fb 1 of integrated luminosity collected by the CDF II detector at the Fermilab Tevatron. The measurements are performed as a function of the photon tr...

We combine searches by the CDF and D0 Collaborations for the standard model Higgs boson with mass in the range 90-200 GeV/c2 produced in the gluon-gluon fusion, WH, ZH, tt̄H, and vector boson fusion processes, and decaying in the H→bb̄, H→WW, H→ZZ, H→ττ, and H→γγ modes. The data correspond to integrated luminosities of up to 10 fb1 and were collect...

This Letter reports a search for a narrow resonant state decaying into two W bosons and two b quarks where one W boson decays leptonically and the other decays into a quark-antiquark pair. The search is particularly sensitive to top-antitop resonant production. We use the full data sample of proton-antiproton collisions at a center-of-mass energy o...

We present a search for new particles in an extension to the standard model that includes a heavy Higgs boson (H0), a lighter charged Higgs boson (H ), and an even lighter Higgs boson h0, with decays leading to a W-boson pair and a bottom-antibottom quark pair in the final state. We use events with exactly one lepton, missing transverse momentum, a...

We present a measurement of the mass difference between top (t) and antitop (t̄) quarks using tt̄ candidate events reconstructed in the final state with one lepton and multiple jets. We use the full data set of Tevatron √s=1.96 TeV proton-antiproton collisions recorded by the CDF II detector, corresponding to an integrated luminosity of 8.7 fb1. We...

Thorough spectral study of the intrinsic single-photon detection efficiency in superconducting TaN and NbN nanowires with different widths shows that the experimental cut-off in the efficiency at near-infrared wavelengths is most likely caused by the local deficiency of Cooper pairs available for current transport. For both materials the reciprocal...

This document describes the technical layout and the expected performance of the Straw Tube Tracker (STT), the main tracking detector of the PANDA target spectrometer. The STT encloses a Micro-Vertex-Detector (MVD) for the inner tracking and is followed in beam direction by a set of GEM-stations. The tasks of the STT are the measurement of the part...

The first observation of the production of a W boson with a single charm quark (c) jet in pp[over ¯] collisions at sqrt[s]=1.96 TeV is reported. The analysis uses data corresponding to 4.3 fb^{-1}, recorded with the CDF II detector at the Fermilab Tevatron. Charm quark candidates are selected through the identification of an electron or muon from c...

This document describes the technical layout and the expected performance of the Straw Tube Tracker (STT), the main tracking detector of the $\overline{P}$ ANDA target spectrometer. The STT encloses a Micro-Vertex-Detector (MVD) for the inner tracking and is followed in beam direction by a set of GEM stations. The tasks of the STT are the measure...

We measure the polarization of W bosons from top-quark (t) decays into final states with a charged lepton and jets, t (t) over bar -> W(+)bW(-)(b) over bar -> lvbq (q) over bar (1)(b) over bar, using the full Run II data set collected by the CDF II detector, corresponding to an integrated luminosity of 8.7 fb(-1). A model-independent method simulta...

We present a combination of searches for the standard model Higgs boson using the full CDF run II data set, which corresponds to an integrated luminosity of 9.45-10.0 fb1 collected from √s=1.96 TeV pp̄ collisions at the Fermilab Tevatron. The searches consider Higgs boson production from gluon-gluon fusion, vector-boson fusion, and associated produ...

We present an updated search for the Higgs boson produced in association with a vector boson in the final state with missing transverse energy and two jets. We use the full CDF data set corresponding to an integrated luminosity of 9.45 fb${}^{-1}$ at a proton-antiproton center-of-mass energy of $\sqrt{s}=1.96$ TeV. New to this analysis is the inclu...

A high-speed YBa2Cu3O7-δ direct detection system was developed to monitor terahertz picosecond pulses in the time domain. High-TC superconducting thin-film YBa2Cu3O7-δ microbridges with critical temperatures of TC = 85 K were embedded into a planar log-spiral antenna to couple the broadband terahertz radiation (0.1 -2 THz) of several picosecond pul...

Svenonius theorem describes the first-order definability in a structure in the terms of groups of permutations of elementary extensions of the structure. In the present paper we reformulate Svenonius theorem in the combinatorial terms.

The lifetime of the Bc- meson is measured using 272 exclusive Bc-→J/ψ(→μμ)π decays reconstructed in data from proton-antiproton collisions corresponding to an integrated luminosity of 6.7 fb1 recorded by the CDF II detector at the Fermilab Tevatron. The lifetime of the Bc- meson is measured to be τ(Bc-)=0.452±0.048(stat)±0.027(syst) ps. This is the...

We present a search for a standard model Higgs boson decaying to two $W$ bosons that decay to leptons using the full data set collected with the CDF II detector in $\sqrts=1.96$ TeV $p\barp$ collisions at the Fermilab Tevatron, corresponding to an integrated luminosity of 9.7 fb$^-1$. We obtain no evidence for production of a standard model Higgs b...

We present the first direct measurement of the top-quark mass using t (t) over bar events decaying in the hadronic tau + jets decay channel. Using data corresponding to an integrated luminosity of 2.2 fb(-1) collected by the CDF II detector in p (p) over bar collisions at root s = 1.96 TeV at the Fermilab Tevatron, we measure the t (t) over bar cro...

We present new measurements of the inclusive forward-backward ttbar production asymmetry, AFB, and its dependence on several properties of the ttbar system. The measurements are performed with the full Tevatron data set recorded with the CDF II detector during ppbar collisions at sqrt(s) = 1.96 TeV, corresponding to an integrated luminosity of 9.4...

We present a measurement of the mass difference between top ($t$) and anti-top ($\bar{t}$) quarks using $t\bar{t}$ candidate events reconstructed in the final state with one lepton and multiple jets. We use the full data set of Tevatron $\sqrt{s} = 1.96$ TeV proton-antiproton collisions recorded by the CDF II detector, corresponding to an integrate...

A search for a narrow Higgs boson resonance in the diphoton mass spectrum is presented based on data corresponding to 10 fb−1 of integrated luminosity collected by the CDF experiment from proton– antiproton collisions at √ s = 1.96 TeV. To increase the sensitivity of the search, we employ a multivariate discriminant technique for the first time in...

We present systematic measurements of the temperature-dependence of detection efficiencies in TaN and NbN superconducting nanowire single-photon detectors. We have observed a clear increase of the cut-off wavelength with decreasing temperature that we can qualitatively describe with a temperature-dependent diffusion coefficient of the quasi-particl...

High-temperature superconducting YBa2Cu3O7-d (YBCO) thin-film detectors with improved responsivities were developed for fast time-domain measurements in the THz frequency range. YBCO thin films of 30 nm thickness were patterned to micro- and nanobridges and embedded into planar log-spiral THz antennas. The YBCO thin-film detectors were characterize...

The primary motivation of the GlueX experiment is to search for and ultimately study the pattern of gluonic excitations in the meson spectrum produced in gamma p collisions. Recent lattice QCD calculations predict a rich spectrum of hybrid mesons that have both exotic and non-exotic JPC, corresponding to q q-bar (q=u, d, or s) states coupled with a...