Extending the Higgs sector: an extra singlet

An extension of the Standard Model with an additional Higgs singlet is analyzed. Bounds on singlet admixture in 125 GeV h boson from electroweak radiative corrections and data on h production and decays are obtained. Possibility of double h production enhancement at 14 TeV LHC due to heavy higgs contribution is considered.Comment: 18 pages, 7 figures. v2: one equation added; references received after the publication of v1 are adde

New Physics at 1 TeV?

If decays of a heavy particle S are responsible for the diphoton excess with invariant mass 750 GeV observed at the 13 TeV LHC run, it can be easily accomodated in the Standard Model. Two scenarios are considered: production in gluon fusion through a loop of heavy isosinglet quark(s) and production in photon fusion through a loop of heavy isosinglet leptons. In the second case many heavy leptons are needed or/and they should have large electric charges in order to reproduce experimental data on $\sigma(pp \to SX) \cdot \mathrm{Br}(S \to \gamma \gamma)$.Comment: 7 pages, 4 figures, 1 tabl

Two-photon physics at future electron-positron colliders

Two photon collisions offer a variety of physics studies that can be performed at the future electron-positron colliders. Using the planned CEPC parameters as a benchmark we consider several topics to be studied in the two-photon collisions. With the full integrated luminosity the Higgs boson photoproduction can be reliably observed. A large statistics of various quarkonium states can be collected. The LEP results on the photon structure function and the tau lepton anomalous magnetic moment can be improved by 1-2 orders of magnitude

Measurement of the energy resolution and calibration of hybrid pixel detectors with GaAs:Cr sensor and Timepix readout chip

This paper describes an iterative method of per-pixel energy calibration of hybrid pixel detectors with GaAs:Cr sensor and Timepix readout chip. A convolution of precisely measured spectra of characteristic X-rays of different metals with the resolution and the efficiency of the pixel detector is used for the calibration. The energy resolution of the detector is also measured during the calibration. The use of per-pixel calibration allows to achieve a good energy resolution of the Timepix detector with GaAs:Cr sensor: 8% and 13% at 60 keV and 20 keV, respectively

pppp scattering at the LHC with the lepton pair production and one proton tagging

Analytical formulas for the cross section of the reaction $pp \to p + \ell^+ \ell^- + X$ are presented. Fiducial cross sections are compared with those measured recently by the ATLAS collaboration.Comment: 12 pages, 1 figur

Weak interaction corrections to muon pair production via the photon fusion at the LHC

Analytical formulas describing the correction due to the $Z$ boson exchange to the cross section of the reaction $pp\rightarrow p\mu^+\mu^- X$ are presented. When the invariant mass of the produced muon pair $W\gtrsim 150~\text{GeV}$ and its total transverse momentum is large, the correction is of the order of 20%.Comment: 17 pages, 5 figure

On production of heavy charged particles in γγ\gamma\gamma fusion at planned pppp colliders

Production of heavy fermions in ultraperipheral collisions ($pp\to p+\gamma\gamma+p\to p+\chi^{+}\chi^{-}+p$) and the semiexclusive reaction ($pp \to p+\gamma\gamma^{*}+X \to p+\chi^{+}\chi^{-}+X$) is considered. Differential and total cross sections for the energies of the planned $pp$ colliders are presented.Comment: 8 pages, 4 figures, 2 table

libepa -- a C++/Python library for calculations of cross sections of ultraperipheral collisions

The library provides a set of C++/Python functions for computing cross sections of ultraperipheral collisions of high energy particles under the equivalent photons approximation. Cross sections are represented through multiple integrals over the phase space. The integrals are calculated through recurrent application of algorithms for one dimensional integration. The paper contains an introduction to the theory of ultraperipheral collisions, discusses the library approach and provides a few examples of calculations.Comment: 25 pages, 6 figures, 1 table. See the arXiv archive for supplementary materials (code

Alignment and resolution studies of a MARS CT scanner

This paper describes a procedure of alignment of MARS CT scanner with cone beam geometry. The position of the xray source relative to the detector, the tilt of the detector are measured during alignment. The mechanical precision of gantry movement is determined. Significant improvement in the quality of image reconstruction has been achieved as a result of the calibration. Spatial resolution (PTF) of the scanner is confirmed to be about 30 μm