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We performed optical photometry and spectral observations of the symbiotic stars 4U1954+319 and ZZ CMi. For 4U1954+319 using high-resolution spectra we measure the equivalent widths of diffuse interstellar bands and estimate the interstellar reddening E(B-V)=0.83 +/- 0.09. Using GAIA distances and our photometry, we find (1) absolute V band magnitude of 4U1954+319 M_V=-5.23 +/- 0.08 and that the mass donor is a supergiant of luminosity class Ib, and (2) for ZZ CMi M_V=-0.27 +/- 0.2 and that the mass donor is a giant of luminosity class III., Comment: submitted to Serbian Astronomical Journal

The goal of this study is to check which, if any, of the published versions of the pion and kaon fragmentation functions is compatible with the STAR data on semi-inclusive pion and kaon production in proton-proton collisions, and on the basis of this analysis to make reliable predictions for the $p_T$ spectra of the pions and kaons in inclusive pion and kaon production at the future NICA proton-proton collider. The calculations are carried out in next-to-leading order (NLO) of perturbative quantum chromodynamics (pQCD), using the well tested CTEQ6 parton distributions. We consider the following pion and kaon fragmentation functions (FFs) -- DSEHS-14, DSEHS-17, LSS-15, HKNS-07 and AKK-08. Our analysis shows that within the experimental errors all tested sets of fragmentation functions provide a good fit to STAR data at the c.m. energy $ \sqrt{S} = 200\, {\rm GeV} $, and the best ones are both LSS-15 and DSEHS-14 for pions and DSEHS-17 for kaons. From comparison of the LO and NLO results it is clear that the latter fit data much better, specially in the region of small $p_T$. The NLO cross sections are also less scale-$Q^2$ dependent, where $p_T/2\leqslant Q \leqslant 2p_T$, than the LO ones. In order to make predictions for NICA energies, we compare the NLO pQCD results with the existing experimental BES STAR data on semi-inclusive hadron production in the most peripheral Au+Au collisions where the nuclear effects can be neglected. The comparison for lower energy scales, like at NICA, shows that a purely pQCD approach is inadequate and suggests the necessity to take into account also higher-order effects of initial-state soft-gluon radiation. Nevertheless, these data on the $p_T$ spectra of $\pi^+$, $K^+$ and also the ratios $\pi^-/\pi^+$ and $K^-/K^+$ seem favour LSS-15 and DSEHS-14 FFs for pions and DSEHS-17 for kaons, similarly as at the energy scale $ \sqrt{S} = 200\, {\rm GeV} $., Comment: 21 pages, 18 figures (40 eps), to be appeared in Int.J.Mod.Phys.A

In series of papers the Boer-Mulders function for a given quark flavour has been extracted: (i) from data on semi-inclusive deep inelastic scattering, using the simplifying, but theoretically inconsistent, assumption that it is proportional to the Sivers function for each quark flavour and (ii) from data on Drell-Yan reactions. In earlier papers, using the semi-inclusive deep inelastic COMPASS deuteron data on the $\langle\cos\phi_h\rangle$ and $\langle\cos 2 \phi_h\rangle$ asymmetries, we extracted the collinear $x_{_{\!B}}$ dependence of the Boer-Mulders function for the sum of the valence quarks $Q_V=u_V + d_V$ using a small number of model dependent assumptions and found a significant disagreement with the analysis in (i). In the present paper, we provide a more complete analysis of the semi-inclusive deep inelastic scattering reaction, including a discussion of higher twist and interaction-dependent terms, and also a comparison with the Boer-Mulders function extracted from data on the Drell-Yan reaction. We confirm that the proportionality relation of the BM function to the Sivers function, for each quark flavour, fails badly, but find that it holds rather well if applied to the nonsinglet valence-quark combination, $Q_V$. We also find good agreement with the results of the Drell-Yan analysis. Furthermore, we obtain interesting information on the quark transverse momentum densities in the nucleon and on the hadron transverse momentum dependence in quark fragmentation., Comment: 15 pages, 9 figures (22 eps plots). This is a more complete study of the subject than in our previous paper arXiv:1909.08218. In this version, Sec. II and V are modified, Fig.5 is replaced, with corresponding slight modifications in the Conclusions; matches published version in Phys.Rev.D

At present, the Boer-Mulders function for a given quark flavour has been extracted from data on semi-inclusive deep inelastic scattering using the simplifying, but theoretically inconsistent, assumption that it is proportional to the Sivers function for each quark flavour. In this paper, using the latest semi-inclusive deep inelastic COMPASS deuteron data on the $\langle\cos\phi_h\rangle$ and $\langle\cos 2 \phi_h\rangle$ asymmetries we extract the collinear $x_B$-dependence of the Boer-Mulders function for the sum of the valence quarks $Q_V=u_V + d_V$ in an essentially model independent way, and find a significant disagreement with the published results. Our analysis also yields interesting information on the transverse momentum dependence of the unpolarized quark distribution and fragmentation functions., Comment: 6 pages, 4 figures

We have calculated the $W$-loop contribution to the amplitude of the decay $H \to Z \gamma$ in the unitary gauge through the dispersion method and in the $R_\xi$ gauge using dimensional regularization (DimReg). We show that the results of the calculations with DimReg and the dispersion method, adopting the boundary condition at the limit $M_W \to 0$ defined by the Goldstone boson equivalence theorem (GBET), completely coincide. This implies that the dispersion method obeying the GBET is compatible with DimReg. The advantage of the applied dispersion method is that we work with finite quantities and no regularization is required., Comment: 6 pages, to be published in the proceedings of DISCRETE2018: 6th Symposium on Prospects in the Physics of Discrete Symmetries, Vienna, 26. - 30. 11. 2018

We have calculated the $W$-loop contribution to the amplitude of the decay $H\rightarrow Z+\gamma$ in two different methods: 1) in the $R_\xi$-gauge using dimensional regularization (DimReg), and 2) in the unitary gauge through the dispersion method. Using the dispersion method we have followed two approaches: i) without subtraction and ii) with subtraction, the subtraction constant being determined adopting the Goldstone boson equivalence theorem (GBET) at the limit $M_W\to 0$. The results of the calculations in $R_\xi$-gauge with DimReg and the dispersion method with the GBET completely coincide, which shows that DimReg is compatible with the dispersion method obeying the GBET., Comment: 16 pages with 15 figures, changes in Sec. IVB, references added

At present, the Boer-Mulders (BM) functions are extracted from asymmetry data using the simplifying assumption of their proportionality to the Sivers functions for each quark flavour. Here we present two independent tests for this assumption. We subject COMPASS data on semi-inclusive deep inelastic scattering on the $\langle\cos\phi_h\rangle$, $\langle\cos 2\phi_h\rangle$ and Sivers asymmetries to these tests. Our analysis shows that the tests are satisfied with the available data if the proportionality constant is the same for all quark flavours, which does not correspond to the flavour dependence used in existing analyses. This suggests that the published information on the BM functions may be unreliable. The $\langle\cos\phi_h\rangle$ and $\langle\cos 2 \phi_h\rangle$ asymmetries receive contributions also from the, in principle, calculable Cahn effect. We succeed in extracting the Cahn contributions from experiment (we believe for the first time) and compare with their calculated values, with interesting implications., Comment: 6 pages , a talk presented at the XVII workshop DSPIN-17 in JINR-Dubna, Russia

The implementation of the process $\gamma\gamma \to ZZ$ at the one-loop level within {\tt SANC} system multi-channel approach is considered. The derived one-loop scalar form factors can be used for any cross channel after an appropriate permutation of their arguments -- Mandelstam variables $s,t,u$. To check of the correctness of the results we observe the independence of the scalar form factors on the gauge parameters and the validity of Ward identity (external photon transversality). We present the complete analytical results for the covariant and tensor structures and helicity amplitudes for this process. We make an extensive comparison of our analytical and numerical results with those existing in the literature., Comment: 12 pages, 4 figures

At present, the Boer-Mulders (BM) function for a given quark flavour is extracted from data on semi-inclusive deep inelastic scattering (SIDIS) using the simplifying assumption that it is proportional to the Sivers function for that flavour. In a recent paper we suggested that the consistency of this assumption could be tested using information on so-called difference asymmetries, i.e. the difference between the asymmetries in the production of particles and their anti-particles. In this paper, using the SIDIS COMPASS deuteron data on the $\langle\cos\phi_h\rangle$, $\langle\cos 2 \phi_h\rangle$ and Sivers difference asymmetries, we carry out two independent consistency tests of the assumption of proportionality, but here applied to the sum of the valence-quark contributions. We find that such an assumption is compatible with the data. We also show that the proportionality assumptions made in the existing parametrizations of the BM functions are not compatible with our analysis, which suggests that the published results for the Boer-Mulders functions for individual flavours are unreliable. The $\langle\cos\phi_h\rangle$ and $\langle\cos 2 \phi_h\rangle$ asymmetries receive contributions also from the, in principle, calculable Cahn effect. We succeed in extracting the Cahn contributions from experiment (we believe for the first time) and compare with their calculated values, with interesting implications., Comment: 20 pages on LaTex.file with 16 figures, Section V with the numerical analysis is totally redone, new subsection VC is added, respectively there are small changes in the Abstract and the Conclusion

Miraculously, target mass corrections for inclusive deep inelastic scattering can be calculated exactly. On the contrary, there does not exist a consistent derivation of kinematic hadron mass corrections for semi-inclusive deep inelastic scattering (SIDIS). Recently this has become of topical interest, since there is a significant difference between the measured HERMES and COMPASS pion and kaon multiplicities, which cannot be explained as a consequence of evolution in $Q^2$, and it has been suggested that the difference can be understood if kinematic hadron mass corrections are taken into account. We explain why this argument is incorrect., Comment: 10 pages with 3 figures, Latex file

Stark broadening parameters for 157 multiplets of helium like boron (B IV) have been calculated using the impact semiclassical perturbation formalism. Obtained results have been used to investigate the regularities within spectral series. An example of the influence of Stark broadening on B IV lines in DO white dwarfs is given., Comment: 6 pages, 2 figures

A major experimental program is presently underway to determine the Sivers, Boer-Mulders and transversity distributions, vital for understanding the internal structure of the nucleon. To this end we consider the Sivers, Boer-Mulders and transversity azimuthal asymmetries of the difference cross sections of hadrons with opposite charges in SIDIS reactions with unpolarized and transversely polarized target l+N\to l'+h+X, h=\pi^\pm, K^\pm, h^\pm. We show that on deuteron target these asymmetries are particularly simple and determine the sum of the valence-quark Q_V=u_V+d_V transverse momentum dependent distributions without any contributions from the strange or other sea-quark functions. At present, data on these asymmetries are presented for the integrated asymmetries i.e. the x_B- and z_h-dependent asymmetries. If data are available in small bins in Q^2, so that Q^2-dependence can be neglected, these expressions simplify dramatically leading to remarkably simple and powerful tests of the simplifying assumptions used in extracting these functions from the data., Comment: 4 pages, a talk given at the XV Advanced Research Workshop on High Energy Spin Physics, DSPIN-15, to appear in the Proceedings, the title and some references are changed

This article presents new features of the MCSANC v.1.20 program, a Monte Carlo tool for calculation of the next-to-leading order electroweak and QCD corrections to various Standard Model processes. The extensions concern implementation of Drell--Yan-like processes and include a systematic treatment of the photon-induced contribution in proton--proton collisions and electroweak corrections beyond NLO approximation. There are also technical improvements such as calculation of the forward-backward asymmetry for the neutral current Drell--Yan process. The updated code is suitable for studies of the effects due to EW and QCD radiative corrections to Drell--Yan (and several other) processes at the LHC and for forthcoming high energy proton--proton colliders.

A major experimental program is presently underway worldwide to determine the fundamental non-perturbative functions, the Sivers, Boer-Mulders and transversity distributions, which are vital for an understanding of the internal structure of the nucleon. However, at present, many simplifying assumptions are used in extracting these functions from the data. We demonstrate that if the binning of the data in Q^2 is small enough so that Q^2-evolution can be neglected inside a bin, then one can obtain stringent tests of these assumptions. Failure to satisfy these tests implies that the presently extracted non-perturbative functions are unreliable. To this end we consider the measurement of the Sivers, Boer-Mulders and transversity difference asymmetries for hadrons with opposite charges in SIDIS reactions with unpolarized and transversely polarized deuteron and proton targets: l+N\to l'+h+X, h=\pi^\pm ,K^\pm ,h^\pm. Utilizing only charge and isospin invariance, and applying the above mentioned simplifying assumptions we obtain several testable relations amongst the measured asymmetries. If these tests are satisfied then the measured asymmetries determine two different combinations of the valence-quark transverse momentum dependent distributions, which can be determined separately without any contributions from the strange and other sea-quarks., Comment: 3 more references and 3 more Sections, where the asymmetries on proton target are considered are added, there are some changes in the Abstract and in the Introduction as well; 22 pages, Latex file

The imaginary part of the Feynman amplitude of the $W$-loop contribution to the Higgs decay into two gammas (viewed as a function of the square of the off shell Higgs momentum) is finite and unambiguous. It is presented as the product of an invariant amplitude ${\cal A}$ times a bilinear in the components of the (on shell) photon momenta factor which takes the Ward identity into account. The unsubtracted dispersion integral of ${\cal A}$ is convergent and reproduces the amplitude computed by R. Gastmans, S.L. Wu and T.T. Wu [GWW]. In particular, the decoupling theorem, criticized as an unjustified assumption in a subsequent paper [SVVZ12], is obtained as a corollary. By contrast with the currently used value (computed in [SVVZ]) our calculation provides a smaller Higgs decay rate into 2 photons than the currently observed. If accepted as a true prediction of the Standard Model, it would be a first indication for the need of a New Physics., Comment: new discussions added at the end of Sec.3, 3 references added, changes at the end of the Abstract

Previously we showed that, based only on C and SU(2) invariance, the difference cross sections of hadrons with opposite charge in SIDIS e+N\to l+h+X is expressed solely in terms of the valence-quark densities and certain non-singlet combinations of FFs. This allowed to determine these quantities in a model independent way. Now we extend this approach to processes when the transverse momentum of the final hadron is measured as well. We show that the difference cross sections of unpolarized SIDIS on proton and deuterium targets, d\s_N^{h^+-h^-}, d\s_N^{\pi^+-\pi^-} and d\s_N^{K^+-K^-}, are expressed solely in terms of the TMD unpolarized valence quark densities and FFs, and the valence-quark Boer-Mulders and Collins functions. This allows to determine them separately and study flavour dependence of the quark transverse momentum. Measurements on deuterium target, d\s_d^{h^+-h^-}, d\s_d^{\pi^+-\pi^-} and d\s_d^{K^+-K^-}, provide 3 independent measurements for the sum of the TMD valence quark densities and Boer-Mulders functions: (u_{1,V}+d_{1,V}) and (h_{1,uV}^\perp + h_{1,dV}^\perp)., Comment: 17 pages, Latex file

We have calculated the polarization of the final nucleon in charged current quasi-elastic \nu -N scattering. We show that the longitudinal and transverse polarizations, as well as their ratio exhibit simple dependence on the axial form factor and their sensitivity to the axial mass is much stronger than that of the cross section. This suggests that measurements of the polarization of the nucleon in the high-statistics neutrino experiments could provide important information on the axial form factor., Comment: 4 pages with 4 figures; a talk given at XV Workshop on High Energy Spin Physics in Dubna, Russia, October 8-12, 2013 (DSPIN 2013)

Stark broadening parameters for 36 multiplets of B IV have been calculated using the semi-classical perturbation formalism. Obtained results have been used to investigate the regularities within spectral series and temperature dependence., Comment: 8 pages, 6 figures, 1 table, in press in Advances in Space Research

The {\tt SANC} computer system is aimed at support of analytic and numeric calculations for experiments at colliders. The system is reviewed briefly. Recent results on high-precision description of the Drell-Yan processes at the LHC are presented. Special attention is paid to the evaluation of higher order final-state QED corrections to the single $W$ and $Z$ boson production processes. A new Monte Carlo integrator {\tt mcsanc} suited for description of a series of high-energy physics processes at the one-loop precision level is presented., Comment: Talk given at ACAT 2013, May 16-21, Beijing, China

New short baseline neutrino experiments open new possibilities of high precision study of different neutrino processes. We present here results of the calculation of the polarization of final nucleon in elastic NC \nu_\mu (\bar\nu_\mu)-nucleon scattering. In a numerical analysis the sensitivity to the different choices of the axial and axial strange form factors is examined. Measurements of the polarization of the final proton in elastic e-p scattering drastically changed our knowledge about the electromagnetic form factors of the proton. From measurement of the nucleon polarization in the NC elastic scattering a new additional information about the axial G_A(Q^2} and the strange axial G^s_A(Q^2) form factors of the nucleon could be inferred., Comment: 19 pages, 4 figures

Measurements of the polarization of the final proton in elastic e-p scattering drastically changed our knowledge about the electromagnetic form factors of the proton. Here we present our results of the calculation of the polarization of the final nucleon in charged current quasi-elastic neutrino nucleon scattering. Relations which connect the axial form factor with the polarization, the cross section and the electromagnetic form factors of the nucleon are derived. Measurements of the polarization of the nucleon in the high-statistics short baseline neutrino experiments (or in near detectors of long baseline experiments) could provide important information on the axial form factor of the nucleon., Comment: Section with numerical results is added which is not in the journal version; 18 pages, 4 figures, Latex file

Modules and packages for the one-loop calculations at partonic level represent the first level of SANC output computer product. The next level represents Monte Carlo integrator mcsanc, realizing fully differential hadron level calculations (convolution with PDF) for the HEP processes at LHC. In this paper we describe the implementation into the framework mcsanc first set of processes: DY NC, DY CC, ff->HW(Z) and single top production. Both EW and QCD NLO corrections are taken into account. A comparison of SANC results with those existing in the world literature is given.

It this paper we present the results obtained with the newly created Standard SANC modules for calculation of the NLO QCD corrections to single top production processes in s and t channels at the partonic level, as well as top-decays. The main aim of these results is to prove the correct work of modules. A comprehensive comparison with results of the CompHEP system is given, where possible. These modules are intended to be used in Monte Carlo generators for single top production processes at the LHC. As in our recent paper, devoted to the electroweak corrections to these processes, we study the regularization of the top-legs associated infrared divergences with aid of the complex mass of the top quark. A comparison of QCD corrections with those computed by the conventional method is presented both for top production and decays. For s channel production we give an analytic proof of equivalence of the two methods in the limit of low top width., Comment: 21 pages, 2 figures, 17 tables

We present a model independent approach to FFs, which allows to determine uniquely the non-singlet combination (D_u-D_d)^{K^++K^-} of the kaon FFs, independently in the three different processes of kaon inclusive production: e+e- annihilation, pp-collisions and lN semi-inclusive DIS. Only C and SU(2) invariances are used and no assumptions on FFs and PDFs, the result holds in any order in QCD. The non-singlets obtained in this way, would allow to test the commonly used assumptions in global fit analysis and to test universality. This method is applied to kaon production data in e+e-\to K+X,\,K=K^\pm, K^0_s and (D_u-D_d)^{K^++K^-} is obtained without any assumptions. This result is compared to the existing parametrizations, obtained in global fit analysis., Comment: eq.(1) is corrected, ref. [5] is added, misprints removed; 6 pages, a talk given by E. Christova at the workshop "Symmetries and SPIN", Prague 18-24 July, 2010, to appear in Eur. Phys. J.- Special Topics

We study the effects of CP violation in charged Higgs boson production $pp\to t H^\pm + X$ at the LHC, as well as in the charged Higgs boson decays $H^\pm \to t b$ and $H^\pm \to W^\pm H_i^0$, $i=1,2,3$. The study is done in the framework of the type II complex Two Higgs Doublet Model (2HDM) with softly broken $Z_2$ symmetry. In this model violation of CP invariance is induced by the complex parameter $m^2_{12}$ of the tree-level Higgs potential. We calculate the CP violating rate asymmetries for $H^+$ and $H^-$ production and decays as well as for the combined processes at one-loop level and perform a detailed numerical analysis. All calculations are done with the automatic amplitude generator FeynArts and the calculational tool FormCalc, for which we have written a complete complex 2HDM model file and relevant fortran drivers. The implementation of the complex 2HDM in FeynArts and FormCalc is described. In comparison with the analogous results in the MSSM, all considered CP violating asymmetries are smaller by an order of magnitude and do not exceed 2 to 3%., Comment: 35 pages, 17 figures, version published in JHEP

We perform fits to the available charged and neutral kaon production data in $e^++e^-\to K+X$, $K=K^\pm and K^0_S$, and determine the non-singlet combination of kaon fragmentation functions $D_u^{K^\pm}-D_d^{K^\pm}$ in a model independent way and without any correlations to the other fragmentation functions. Only nuclear isospin invariance is assumed. Working with non-singlets allows us to include the data at very low momentum fractions, which have so far been excluded in global fits, and to perform a first NNLO fit to fragmentation functions. We find that the kaon non-singlet fragmentation function at large $z$ is larger than that obtained by the other collaborations from global fit analysis and differs significantly at low $z$.

We show that the difference cross sections in unpolarized SIDIS e+N\to e+h+X and pp hadron production p+p\to h+X determine, uniquely and in any order in QCD, the two FFs: D_u^{h-\bar h} and D_d^{h-\bar h}, h=\pi^\pm, K^\pm. If both K^\pm and K_s^0 are measured, then e+e-\to K+X, e+N\to e+K+X and p+p\to K+X yield independent measurements of (D_u-D_d)^{K^+ +K^-}. In a combined fit to K^\pm and K^0_s production data from e+e- collisions, (D_u-D_d)^{K^++K^-} is obtained and compared to conventional parametrizations., Comment: 4 pages, 1 figure, LaTex, talk given at the XIII workshop on High Energy Spin Physics, Dubna, Russia, 1-5 Sept. 2009, DSPIN-2009, to appear in the proceedings, typos corrected

We study CP violation in associated production of a charged Higgs boson and a top quark at the LHC, $pp \to tH^\pm +X$. The asymmetry between the total cross sections for $H^+$ and $H^-$ production at next-to-leading order in the MSSM is calculated analytically and a detailed numerical analysis is performed. Furthermore, subsequent decays of $H^\pm$ to $tb$ and $ \tau^\pm \nu_\tau$ are considered. In the case with $H^\pm \to tb$ decay the asymmetry can go up to $\sim$~12%., Comment: A contributed talk given by E. Ginina at the 17th International Conference on Supersymmetry and the Unification of Fundamental Interactions, SUSY09, June 2009, Boston, US, to appear in the proceedings of the conference

In this paper we present the results of the implementation of the decay t -> b f1 f1 into the SANC system (f1 is a massless fermion). The new aspect of the work is the combination of QCD and EW corrections. All calculations are done at the one-loop level in the Standard Model. We give a detailed account of the new procedure - the forming of a class of JAW,WA functions. These functions are related to the procedure of extraction of infra-red and mass-shell singular divergences. The emphasis of this paper is on the presentation of numerical results for various approaches: complete one-loop calculations and different versions of pole approximations.

NLO QCD corrections to charged and neutral current Drell-Yan processes and their implementation in the computer system SANC are considered. On the partonic level both quark-antiquark and quark-gluon scattering channels are taken into account. Subtractions of the collinear singularities in the massive case are compared with ones in the MS-bar scheme. Results of SANC on the hadronic level are presented. Comparison with results of the MCFM package is shown., Comment: 16 pages, 2 figures

We study effects of CP violation in the associated production of a charged Higgs boson and a top quark at the LHC, $pp \to tH^\pm + X$. We calculate the CP violating asymmetry between the total cross section for $H^+$ and $H^-$ production at next-to-leading order in the MSSM, and perform a detailed numerical analysis. In the production the asymmetry is of the order of 20%. The asymmetry in the production and any subsequent decay of an on-shell charged Higgs boson is to a good approximation the sum of the asymmetry in the production and the asymmetry in the decay. We consider subsequent decays of $H^\pm $ to $t b$, $\nu_\tau \tau^\pm$ and $W h^0$. In the case with $H^\pm \to t b$ decay, mainly due to CP violating box graphs with gluino, the asymmetry can go up to $\sim$ 12%., Comment: version published in PRD

In this note we summarize the status of the standard SANC modules (in the EW and QCD sectors of the Neutral Current branch - version 1.20 and the Charged Current branch - version 1.20). All versions of the codes are accessible from the SANC project servers at Dubna http://sanc.jinr.ru and CERN http://pcphsanc.cern.ch