arXiv subjects

O. P. Yushchenko

Publications and source records attributed to O. P. Yushchenko.

27 records · Page 2Linked to original sources

arXiv2003

High statistic study of the K- -> pi0 mu- nu decay

The decay K- -> pi0 mu- nu has been studied using in-flight decays detected with the "ISTRA+" spectrometer. About 540K events were collected for the analysis. The lambda+ and lambda0 slope parameters of the decay form-factors f+(t), f0(t) have been measured : lambda+ = 0.0277+-0.0013 (stat)+-0.0009 (syst), lambda0 = 0.0183+-0.0011(stat)+-0.0006(syst), and d(lambda0)/d(lambda+)=-0.348. The limits on the possible tensor and scalar couplings have been derived: fT/f+(0)=-0.0007 +- 0.0071, fS/f+(0)=0.0017 +- 0.0014. No visible non-linearity in the form-factors have been observed.

hep-ex↗

arXiv2003

High statistics study of the K- -> pi0 e- nu decay

The decay K- -> pi0 e- nu has been studied using in-flight decays detected with the "ISTRA+" spectrometer working at the 25 GeV negative secondary beam of the U-70 PS. About 550K events were used for the analysis. The lambda+ parameter of the vector form-factor has been measured: lambda+ = 0.0286 +- 0.0008 (stat) +- 0.0006(syst). The limits on the possible tensor and scalar couplings have been obtained: f(T)/f+(0)=0.021 +0.064 -0.075 (stat) +- 0.026(syst) ; f(S)/f+(0)=0.002 +0.020 -0.022 (stat) +- 0.003(syst)

hep-ex↗

arXiv2003

Measurement of the Dalitz plot slope parameters for K- -> pi0 pi0 pi- decay using ISTRA+ detector

The Dalitz plot slope parameters g, h and k for the K- -> pi0 pi0 pi- decay have been measured using in-flight decays detected with the ISTRA+ setup operating in the 25 GeV negative secondary beam of the U-70 PS. About 252 K events with four-momenta measured for the pi- and four involved photons were used for the analysis. The values obtained g=0.627+/-0.004(stat)+/-0.010(syst), h=0.046+/-0.004(stat)+/-0.012(syst), k=0.001+/-0.001(stat)+/-0.002(syst) are consistent with the world averages dominated by K+ data, but have significantly smaller errors.

hep-ex↗

arXiv2003

Possibility of Measuring the CP-Violation gamma-parameter in Decays of Xi_bc Baryons

The model-independent method based on the triangle ideology is implemented to extract the CKM-matrix angle gamma in the decays of doubly heavy baryons containing the charmed and beauty quarks. We analyze a color structure of diagrams and conditions for reconstructing two reference-triangles by tagging the flavor and CP eigenstates of neutral D mesons in the fixed exclusive channels. The characteristic branching ratios are evaluated in the framework of a potential model setting a parametric dependence on the hadronic matrix elements for the decay rates.

hep-ph↗

arXiv2002

Prospects for the Bc Studies at LHCb

We discuss the motivations and perspectives for the studies of the mesons of the (bc) family at LHCb. The description of production and decays at LHC energies is given in details. The event yields, detection efficiencies, and background conditions for several Bc decay modes at LHCb are estimated.

hep-ph↗

arXiv1998

Search for Anomalous Top--Quark Interaction at LEP-2 Collider

We show that a search for $e^+ e^- \to t \bar q$ $(\bar q = \bar c, \bar u)$ events at LEP--2 collider provide a possibility to improve significantly the modern constraints on coupling constants of anomalous $t$--quark interaction via flavor--changing neutral currents.

hep-ph↗

arXiv1997

CP Violating Anomalous Couplings at a 500 GeV e+ e- Linear Collider

We study the sensitivity of a 500 GeV $e^+e^-$ Linear Collider to $CP$ violating anomalous couplings. We find that with 50~fb$^{-1}$, and taking only one non-zero coupling at a time, the process $e^+e^-\to W^+ W^-$ can be used to place the 95% confidence level bounds $|\tildeκ_γ|\leq0.1$, $|\tildeκ_Z|\leq 0.1$ and $|g_4^Z|\leq 0.1$ from CP even observables. By studying certain distributions in the process $e^+e^-\to μ^+μ^-ν\barν$ one of the bounds can be improved to $|g_4^Z| \leq 0.06$. This process also allows the construction of a CP odd observable which can be used to place bounds on CP violating new physics. At the 95% confidence level we find $|\tildeκ_γ|\leq 0.3$, $|\tildeκ_Z|\leq 0.2$ and a much weaker bound for $|g_4^Z|$.

hep-ph↗

arXiv1995

Some Features of the Hadronic $B_c^{(*)}$-meson Production at Large $p_T$

Calculations of the hadronic $B^{(*)}_c$-mesons production performed in the framework of the perturbative QCD taking into account $O(α_s^4)$ Feynmann diagrams are presented. A comparison of the exact calculations with those based on the fragmentation model of $\bar b\rightarrow B^{(*)}_c+X$ shows the large discrepancy between them. The exact calculations of the $B^{(*)}_c$-mesons production cross-sections as the function of $p_T$ at the energy of the FNAL Tevatron ($\sqrt{s}=1.8$ TeV) are given. The predicted ratio of the vector to the pseudoscalar state cross-sections is about $R\sim 3$ instead of $R\sim 1.4$ for the fragmentation model.

hep-ph↗

arXiv1993

Probing Three-Boson Anomalous Couplings in $e^+e^-\to W^+W^-$ at Future Linear $e^+e^-$ Colliders with Polarized Beams

We study the potential of the next-generation $e^+ e^-$ linear colliders with longitudinally polarized beams, to restrict the values of the anomalous trilinear couplings $WWγ$ and $WWZ$ from the measurement of the process $e^+ e^-\to W^+ W^-$. Along with initial $e^+e^-$ polarization, we account also for the possibilities offered by cross sections for polarized final $W$, in order to disentangle the constraints on the various constants. The results show the essential role of the initial beams polarization in improving the bounds obtained from the unpolarized case.

hep-ph↗