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N. I. Troitskaya

Publications and source records attributed to N. I. Troitskaya.

At least 37 records · Page 2Linked to original sources
arXiv2017

Precision Theoretical Analysis of Neutron Radiative Beta Decay to Order "O(α^2/π^2)"

In the Standard Model (SM) we calculate the decay rate of the neutron radiative beta decay to order "O(α^2/π^2 ~ 10^{-5})", where "α$"is the fine--structure constant, and radiative corrections to order "O(α/π~ 10^{-3})". The obtained results together with the recent analysis of the neutron radiative beta decay to next-to-leading order in the large proton-mass expansion, performed by Ivanov et al. Phys. Rev. D95, 033007 (2017), describe recent experimental data by the RDK II Collaboration (Bales et al., Phys. Rev. Lett. 116, 242501 (2016)) within 1.5 standard deviations. We argue a substantial influence of strong low-energy interactions of hadrons coupled to photons on the properties of the amplitude of the neutron radiative beta decay under gauge transformations of real and virtual photons.

hep-ph↗
arXiv2017

Precision Theoretical Analysis of Neutron Radiative Beta Decay

In the Standard Model of electroweak interactions and in the tree--approximation we calculate the rate and branching ratio of the neutron radiative beta decay with one-real photon emission by taking into account the contributions of the weak magnetism and proton recoil to order 1/m_p of the large proton mass m_p expansion. We find that the obtained contributions of the weak magnetism and proton recoil increase the rate and branching ratio of the neutron radiative beta decay by about 0.70%. This is large compared with the contribution of the weak magnetism and proton recoil of about 0.16% to the rate of the neutron beta decay, calculated in Phys. Rev. D88, 073002 (2013).

hep-ph↗
arXiv2013

Deficit of reactor antineutrinos at distances smaller than 100 m and inverse beta-decay

We analyse a change of a deficit of reactor antineutrinos at distances smaller than 100 m by changing the lifetime of the neutron from tau_n = 885.7 s to tau_n = 879.6 s, calculated for the axial coupling constants lambda = - 1.2694 and lambda = - 1.2750, respectively, in order to get a result corresponding the new world average value tau_n = 880.1(1.1) s. We calculate the angular distribution and cross section for the inverse beta-decay, taking into account the contributions of the "weak magnetism" and the neutron recoil to next-to-leading order in the large baryon mass expansion and the radiative corrections of order alpha/π~ 10^(-3), calculated to leading order in the large baryon mass expansion. We obtain an increase of a deficit of reactor antineutrinos in of about 0.734%.

hep-ph↗
arXiv2013

Proton Recoil Energy and Angular Distribution of Neutron Radiative Beta Decay

We analyse the proton recoil energy and angular distribution of the radiative beta-decay of the neutron to leading order in the large baryon mass expansion by taking into account the contributions of the proton-photon correlations. We show that the account for the proton-photon correlations does not contradict the description of the radiative corrections to the lifetime of the neutron and the proton recoil energy spectrum of the neutron beta-decay in terms of the functions (α/π) g_n(E_e) and (α/π) f_n(E_e), where E_e is the electron energy. In addition we find that the contributions of the proton-photon correlations in the radiative beta-decay of the neutron to the proton recoil asymmetry C are of order 10^(-4). They make the contributions of the radiative corrections to the proton recoil asymmetry C symmetric with respect to a change A_0 <--> B_0, where A_0 and B_0 are the correlation coefficients of the neutron beta-decay.

hep-ph↗
arXiv2011

Energy Level Displacement of Excited np State of Kaonic Deuterium In Faddeev Equation Approach

We calculate the energy level displacement of the excited $np$ state of kaonic deuterium in terms of the P-wave scattering length of $K^-d$ scattering. We solve the Faddeev equations for the amplitude of $K^-d$ scattering in the fixed centre approximation and derive the complex P-wave scattering length of $K^-d$ scattering in terms of the S-wave and P-wave scattering lengths of $\bar{K}N$ scattering. The estimated uncertainty of the complex P-wave scattering length is of about $15\,%$. For the calculated width $Γ_{2p} = 10.203\,{\rm meV}$ of the excited $2p$ state of kaonic deuterium we evaluate the yield $Y_{K^-d} = 0.27\,%$ of $X$-rays for the $K_α$ emission line of kaonic deuterium. Using the complex S-wave and P-wave scattering lengths of $\bar{K}N$ scattering, calculated in \cite{ECL1,Weise1}, we get the width $Γ_{2p} = 2.675\,{\rm meV}$ of the excited $2p$ state and the yield $Y_{K^-d} = 1.90 \,%$ of $X$-rays for the $K_α$ emission line of kaonic deuterium. The results, obtained in this paper, can be used for the planning of experiments on the measurements of the energy level displacement of the ground state of kaonic deuterium, caused by strong low-energy interactions.

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arXiv2009

On the influence of the magnetic field of the GSI experimental storage ring on the time-modulation of the EC-decay rates of the H-like mother ions

We investigate the influence of the magnetic field of the Experimental storage ring (ESR) at GSI on the periodic time-dependence of the orbital K-shell electron capture decay $(EC$) rates of the H--like heavy ions. We approximate the magnetic field of the ESR by a uniform magnetic field. Unlike the assertion by Lambiase et al., arXiv: 0811.2302 [nucl-th], we show that a motion of the H-like heavy ion in a uniform magnetic field cannot be the origin of the periodic time-dependence of the EC-decay rates of the H-like heavy ions.

nucl-th↗
arXiv2009

On Continuum-State and Bound-State Beta Decay Rates of the Neutron

We analyse the continuum-state and bound-state beta^-decay rates of the neutron. For the calculation of theoretical values of the decay rates we use the new value for the axial coupling constant g_A = 1.2750(9), obtained recently by H. Abele (Progr. Part. Nucl. Phys., 60, 1 (2008)) from the fit of the experimental data on the neutron spin-electron correlation coefficient of the electron energy spectrum of the continuum-state beta^- decay of the neutron. We take into account the contribution of radiative corrections and the scalar and tensor weak couplings. We define correlation coefficients of the electron energy spectrum in terms of axial, scalar and tensor coupling constants. Using recent precise experimental data for the lifetime of the neutron and correlation coefficients we estimate the scalar and tensor weak coupling constants. The bound-state beta^- decay rates of the neutron we calculate as functions of axial, scalar and tensor weak coupling constants. We show that dominantly the neutron decays into hydrogen in the hyperfine states with total angular momentum F = 0. The calculated angular distributions of the probabilities of the bound-state beta^- decays of the polarised neutron can be used for the experimental measurements of the bound-state beta^- decays into the hyperfine states with a total angular momentum F = 1.

hep-ph↗
arXiv2009

On Bound-State beta^- Decay Rate of the Free Neutron

We calculate the bound-state beta^- decay rate of the free neutron. We show that hydrogen in the final state of the decay is produced with a probability of about 99% in the hyperfine state with zero orbital l = 0 and atomic angular momentum F = 0.

hep-ph↗
arXiv2008

Can the "Darmstadt oscillations" be treated as two closely spaced mass-eigenstates of the H-like mother ions ?

We discuss the proposal that the "Darmstadt oscillations" of the orbital K-shell electron capture decay (EC) rate of the H-like heavy ions are caused by quantum beats of two coherently excited, closely spaced mass-eigenstates of decaying H-like heavy ions. We show that such a mechanism to explain the time modulation of the EC-decay rates of the H-like heavy ions leads to the time modulation of the beta^+ decay rate of these ions with the same period. Such a time-dependence of the beta^+ decay rate of the H-like heavy ions contradicts the experimental data of GSI.

nucl-th↗
arXiv2008

First-Forbidden Continuum- and Bound-State beta^- -Decay Rates of Bare 205Hg80+ and 207Tl81+ Ions

We calculate the decay rates lambda_(beta^-_c) and lambda_(beta^-_b) of the continuum- and bound-state beta^- decays for bare 205Hg80+ and 207Tl81+ ions. For the ratio of the decay rates R_(b/c) = lambda_(beta^-_b)/lambda_(beta^-_c) we obtain the values R_(b/c) = 0.161 and R_(b/c) = 0.190 for bare 205Hg80+ and 207Tl81+ ions, respectively. The theoretical value of the ratio R_(b/c) = 0.190 for the decays of 207Tl81+ agrees within 1% of accuracy with the experimental data R^exp_(b/c) = 0.188(18), obtained at GSI. The theoretical ratio R_(b/c) = 0.161 for 205Hg80+ is about 20% smaller than the experimental value R^exp_(b/c) = 0.20(2), measured recently at GSI.

nucl-th↗
arXiv2006

On strangeness production in the reactions pp -> p Lambda^0 K^+ and pn -> n Lambda^0 K^+ near threshold

The cross sections for the reactions pp -> p Lambda^0K^+ and pn -> n Lambda^0K^+ are calculated near threshold of the final states. The theoretical ratio of the cross sections R = sigma(pn -> n Lambda^0K^+)/ sigma(pp ->pΛ^0K^+) = 3 shows the enhancement of the pn interaction with respect to the pp interaction near threshold of the strangeness production N Lambda^0K^+. Such an enhancement is caused by the contribution of the np interaction in the isospin-singlet state, which is stronger than the $pn$ interaction in the isospin-triplet state. For the confirmation of this result we calculate the cross sections for the reactions pp -> pp pi^0, pi^0 p -> Lambda^0 K^+ and pi^-p -> Lambda^0 K^0 near threshold of the final states. The theoretical cross sections agree well with the experimental data.

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arXiv2006

On kaonic deuterium. Quantum field theoretic and relativistic covariant approach

We study kaonic deuterium, the bound K^-d state A_(K d). Within a quantum field theoretic and relativistic covariant approach we derive the energy level displacement of the ground state of kaonic deuterium in terms of the amplitude of K^-d scattering for arbitrary relative momenta. Near threshold our formula reduces to the well-known DGBT formula. The S-wave amplitude of K^-d scattering near threshold is defined by the resonances Lambda(1405), Sigma(1750) and a smooth elastic background, and the inelastic channels K^- d -> NY and K^- d -> NY pion, with Y = Sigma^(+/-), Sigma^0 and Lambda^0, where the final-state interactions play an important role. The Ericson-Weise formula for the S-wave scattering length of K^-d scattering is derived. The total width of the energy level of the ground state of kaonic deuterium is estimated using the theoretical predictions of the partial widths of the two-body decays A_(Kd) -> NY and experimental data on the rates of the NY-pair production in the reactions K^-d -> NY. We obtain Gamma_{1s} = (630 +/-100) eV. For the shift of the energy level of the ground state of kaonic deuterium we predict epsilon_(1s) = (353 +/-60)eV.

nucl-th↗
arXiv2006

On kaonic hydrogen. Phenomenological quantum field theoretic model revisited

We argue that due to isospin and U-spin invariance of strong low-energy interactions the S-wave scattering lengths a^0_0 and a^1_0 of bar-KN scattering with isospin I=0 and I = 1 satisfy the low-energy theorem a^0_0 + 3 a^1_0 = 0 valid to leading order in chiral expansion. In the model of strong low-energy bar-KN interactions at threshold (EPJA 21,11 (2004)) we revisit the contribution of the Sigma(1750) resonance, which does not saturate the low-energy theorem a^0_0 + 3 a^1_0 = 0, and replace it by the baryon background with properties of an SU(3) octet. We calculate the S-wave scattering amplitudes of K^-N and K^-d scattering at threshold. We calculate the energy level displacements of the ground states of kaonic hydrogen and kaonic deuterium. The result obtained for kaonic hydrogen agrees well with recent experimental data by the DEAR Collaboration. We analyse the cross sections for elastic and inelastic K^-p scattering for laboratory momenta of the incident K^- meson from the domain 70 MeV/c < p_K < 150 MeV/c. The theoretical results agree with the available experimental data within two standard deviations.

nucl-th↗
arXiv2005

On the estimate of the sigma^(I = 1)_(KN)(0)-term value from the energy level shift of kaonic hydrogen in the ground state

Using the experimental data on the energy level shift of kaonic hydrogen in the ground state (the DEAR Collaboration, Phys. Rev. Lett. 94, 212302 (2005)) and the theoretical value of the energy level shift, calculated within the phenomenological quantum field theoretic approach to the description of strong low-energy anti-K N and anti-K NN interactions developed at Stefan Meyer Institut fuer subatomare Physik in Vienna, we estimate the value of the sigma^(I = 1)_(KN)(0)-term of low-energy anti-K N scattering. We get sigma^(I = 1)_(KN)(0) = (433 +/- 85) MeV. This testifies the absence of strange quarks in the proton structure.

nucl-th↗
arXiv2005

On the Sigma^0 --> Lambda^0 + gamma decay in the Effective quark model with chiral U(3)xU(3) symmetry

We analyse the angular distributions of the Sigma^0 --> Lambda^0 + gamma decay rate in the laboratory and in the rest frame of the Sigma^0 - hyperon in the dependence on baryon polarizations. We calculate the dynamical polarization vector of the Lambda^0 - hyperon. Within the Effective quark model with chiral U(3) x U(3) symmetry (PRC 59, 451 (1999)) we calculate the transition magnetic moment mu_(Sigma^0 Lambda^0). The theoretical value mu_(Sigma^0 Lambda^0) = - 1.62, measured in nuclear magnetons, agrees well with the experimental data |mu^(\exp)_(Sigma^0 Lambda^0)| = (1.61 +/-0.08) and the theoretical result, predicted within the naive quark model mu_(Sigma^0 Lambda^0) = (\sqrt{3}/4)(mu_(Sigma^-) - mu_(Σ^+)) = (- 1.57 +/- 0.01).

hep-ph↗
arXiv2005

Recent Theoretical Studies on Hadronic Atoms

A report contains a review of recent theoretical investigations on kaonic atoms carried out at Stefan Meyer Institute of the Austrian Academy of Sciences. We discuss (1) a phenomenological quantum field theoretic model for bar-K N interactions at threshold of the reactions K^-p -> K^-p, K^-n -> K^-n and K^-d ->K^-d, and (2) the energy level displacements of the ground and nP excited states of kaonic hydrogen, (3) the contribution of the sigma-term to the shift of the energy level of the ground state of kaonic hydrogen, (4) the isospin-breaking and dispersive corrections to the energy level displacement of the ground state of kaonic hydrogen, (5) the radiative transitions nP -> 1S + γ, induced by strong low-energy interactions and enhanced by the Coulomb interaction, in kaonic hydrogen and kaonic deuterium, (6) Perspectives and (7) Comments on the approach, where we adduce our recent results obtained after the Workshop EXA05.

nucl-th↗
arXiv2005

Energy level displacement of excited np states of kaonic hydrogen

We compute the energy level displacement of the excited np states of kaonic hydrogen within the quantum field theoretic and relativistic covariant model of strong low-energy bar-KN interactions suggested in EPJA21, 11 (2004). For the width of the energy level of the excited 2p state of kaonic hydrogen, caused by strong low-energy interactions, we find Gamma_2p = 2 meV. This result is important for the theoretical analysis of the X-ray yields in kaonic hydrogen.

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