Fedor Simkovic - Academia.edu (original) (raw)
Papers by Fedor Simkovic
Journal of the Korean Physical Society, 2008
![Research paper thumbnail of Nuclear and particle physics aspects of the 2νββ-decay of [sup 150]Nd](https://attachments.academia-assets.com/95169923/thumbnails/1.jpg)
](AIP Conference Proceedings, 2007
A discussion is given on possible realization of the Single State Dominance (SSD) hypothesis in t... more A discussion is given on possible realization of the Single State Dominance (SSD) hypothesis in the case of the two-neutrino double beta decay (2νββ-decay) of 150 N d with 1 − ground state of the intermediate nucleus. We conclude that the SSD hypothesis is expected to be ruled out by precision measurement of differential characteristics of this process in running NEMO 3 or planed SuperNEMO experiments unlike some unknown low-lying 1 + state of 150 P m does exist. This problem can be solved via (d, 2 He) charge-exchange experiment on 150 Sm. Further, we address the question about possible violation of the Pauli exclusion principle for neutrinos and its consequences for the energy distributions of the 2νββ-decay of 150 N d. This phenomenon might be a subject of interest of NEMO 3 and SuperNEMO experiments as well.
AIP Conference Proceedings, 2009
In order to understand the basic nature of the Universe in which we live, we must to understand a... more In order to understand the basic nature of the Universe in which we live, we must to understand and observe relic neutrinos, which evade direct detection so far. For number density of relic neutrinos per flavour< η>= 56 cm− 3 [Giunti and Kim, 2007] a direct ...
The longitudinal form factors of the weak vector current of particles with spin J = 1/2 and isosp... more The longitudinal form factors of the weak vector current of particles with spin J = 1/2 and isospin I = 1/2 are determined by the mass difference and the charge radii of members of the isotopic doublets. The most promising reactions to measure these form factors are the reactions with large momentum transfers involving the spin-1/2 isotopic doublets with a maximum mass splitting. Numerical estimates of longitudinal form factors are given for nucleons and eight nuclear spin-1/2 isotopic doublets.
International Journal of Modern Physics E, 2006
A set of moderately deformed s–d shell nuclei is employed for testing the reliability of the nucl... more A set of moderately deformed s–d shell nuclei is employed for testing the reliability of the nuclear ground state wave functions which are obtained in the context of a BCS approach and offer a simultaneous consideration of deformation and pairing correlations effects. In this method, the mean field is assumed to be an axially symmetric Woods-Saxon potential and the effective two-body interaction is a monopole pairing force. As quantities of main interest we have chosen the nuclear form factors, the occupancies of the active (surface) orbits and the Fermi sea depletion, which provide quite good tests for microscopic descriptions of nuclei within many body theories. For our comparisons with results emerging from other similar methods, an axially deformed harmonic oscillator field is also utilized.
Acta Physica Polonica Series B
We present new formulae for the neutrino masses generated by R-parity violating interactions with... more We present new formulae for the neutrino masses generated by R-parity violating interactions within minimal supersymmetric standard model. The importance of inclusion of CP phases in the neutrino mass matrix is discussed in detail.
In a previous article [Phys. Rev. D 79, 053001 (2009)] we estimated the correlated uncertainties ... more In a previous article [Phys. Rev. D 79, 053001 (2009)] we estimated the correlated uncertainties associated to the nuclear matrix elements (NME) of neutrinoless double beta decay (0νββ) within the quasiparticle random phase approximation (QRPA). Such estimates encompass recent independent calculations of NMEs, and can thus still provide a fair representation of the nuclear model uncertainties. In this context, we compare the claim of 0νββ decay in 76 Ge with recent negative results in 136 Xe and in other nuclei, and we infer the lifetime ranges allowed or excluded at 90% C.L. We also highlight some issues that should be addressed in order to properly compare and combine results coming from different 0νββ candidate nuclei.
International Journal of Modern Physics E, 2006
The presence of trilinear R-parity violating interactions in the MSSM lagrangian leads to existen... more The presence of trilinear R-parity violating interactions in the MSSM lagrangian leads to existence of quark–squark and lepton–slepton loops which generate mass of the neutrino. By introducing interaction with an external photon the magnetic moment is obtained. We derive bounds on that quantity being around one order of magnitude stronger than those present in the literature.
A formal relation between the GT part of the nuclear matrix elements M 0ν GT of 0νβ β decay and t... more A formal relation between the GT part of the nuclear matrix elements M 0ν GT of 0νβ β decay and the closure matrix elements M 2ν cl of 2νβ β decay is established. This relation is based on the integral representation of these quantities in terms of their dependence on the distance r between the two nucleons undergoing transformation. We also discuss the difficulties in determining the correct values of the closure 2νβ β decay matrix elements.
We have performed a critical analysis of different approximation schemes for the calculation of t... more We have performed a critical analysis of different approximation schemes for the calculation of two-neutrino double beta decay (TNDBD) matrix elements. We have shown that within the single-particle approximation of nuclear Hamiltonian the TNDBD matrix element is equal to zero. The (renormalized) quasiboson approximation scheme imply for TNDBD transition operator to be a constant, if one requires the equivalence of initial and final (renormalized) QRPA Hamiltonians. It means that TNDBD is a higher order process in the boson expansion of the nuclear Hamiltonian. We have found that the mismatching of both Hamiltonians is getting worse with increasing strength of particle- particle interaction especially in the case of QRPA Hamiltonians. It is supposed to be one of the reasons of the extreme sensitivity of studied matrix element to the residual interaction appearing in explicit calculations involving the intermediate nucleus. Further, the Operator Expansion Method (OEM) has been reconsi...
In view of recent great progress achieved in the experimental study of the neutrinoless double be... more In view of recent great progress achieved in the experimental study of the neutrinoless double beta decay (0nbb-decay) of 134Xe we discuss theoretical aspects of this process. The light and heavy Majorana neutrino exchange as well as the trilinear R-parity breaking contributions to 0nbb-decay are considered. We show that the sensitivity of the studied process to the signal of lepton number violation is only by factor 2-3 weaker in comparison with the 0nbb-decay of 136Xe. The current limits on effective neutrino mass (light and heavy) and trilinear R-parity violating parameter lambda'_111 deduced from lower limits on the 0nbb-decay half-lifes of various nuclei are reviewed and perspectives of the experimental verification of recently announced evidence of the 0nbb-decay of 76Ge are discussed.
Physical Review D, 2006
The transition magnetic moments of Majorana neutrinos µν ij (ij = eµ, eτ, µτ) are calculated in g... more The transition magnetic moments of Majorana neutrinos µν ij (ij = eµ, eτ, µτ) are calculated in grand unified theory (GUT) constrained Minimal Supersymmetric Standard Model (MSSM) with explicit R-parity violation. It is assumed that neutrinos acquire masses via one-loop (quark-squark and lepton-slepton) radiative corrections. The mixing of squarks, sleptons, and quarks is considered explicitly. The connection between µν ij and the entries of neutrino mass matrix is studied. The current upper limits on µν ij are deduced from the elements of phenomenological neutrino mass matrix, which is reconstructed using the neutrino oscillation data and the lower bound on the neutrinoless double beta decay half-life. Further, the results for µν eµ , µν eτ and µν µτ are presented for the cases of inverted and normal hierarchy of neutrino masses and different SUSY scenarios. The largest values are of the order of 10 −17 in units of Bohr magneton.
Physical Review D, 2008
At the quark level there are basically two types of contributions of R-parity violating SUSY (Rp ... more At the quark level there are basically two types of contributions of R-parity violating SUSY (Rp / SUSY) to neutrinoless double beta decay: the short-range contribution involving only heavy virtual superpartners and the long-range one with the virtual squark and neutrino. Hadronization of the effective operators, corresponding to these two types of contributions, may in general involve virtual pions in addition to close on-mass-shell nucleons. From the previous studies it is known that the short-range contribution is dominated by the pion exchange. In the present paper we show that this is also true for the long-range Rp / SUSY contribution. Therefore, we conclude that the Rp / SUSY contributes to the neutrinoless double beta decay dominantly via charged pion exchange between the decaying nucleons.
Physical Review D, 2004
We study nuclear µ − − e − conversion in the general framework of an effective Lagrangian approac... more We study nuclear µ − − e − conversion in the general framework of an effective Lagrangian approach without referring to any specific realization of the physics beyond the standard model (SM) responsible for lepton flavor violation (L f /). We examine the impact of a specific hadronization prescription on the analysis of new physics in nuclear µ − −e − conversion and stress the importance of vector meson exchange between lepton and nucleon currents. A new issue of this mechanism is the presence of the strange quark vector current contribution induced by the φ meson. This allows us to extract new limits on the L f / lepton-quark effective couplings from the existing experimental data.
Physical Review D, 1998
We discuss some phenomenological issues of the effective quarklepton operators emerging from the ... more We discuss some phenomenological issues of the effective quarklepton operators emerging from the bilinear lepton-Higgs couplings in the superpotential and in the soft supersymmetry (SUSY) breaking sector of the supersymmetric models without R-parity. The contribution of these operators to the neutrinoless double beta decay (0νββ) is derived. The corresponding nuclear matrix elements are calculated within the renormalized quasiparticle random phase approximation, which includes the Pauli effect of fermion pairs and does not collapse for the physical values of the nuclear force strength. On this basis we extract from the experimental data new stringent limits on the 1st generation mass parameter characterized the lepton-Higgs bilinear coupling and on the electron sneutrino vacuum expectation value.
Physical Review C, 2004
The Minimal Supersymmetric Standard Model with gauge mediated supersymmetry breaking and trilinea... more The Minimal Supersymmetric Standard Model with gauge mediated supersymmetry breaking and trilinear R-parity violation is applied to the description of neutrinoless double beta decay. A detailed study of limits on the parameter space coming from the B → Xsγ processes by using the recent CLEO results is performed. The importance of two-nucleon and pion-exchange realizations of 0νββ decay together with gluino and neutralino contributions to this process are addressed. We have deduced new limits on the trilinear R-parity breaking parameter λ ′ 111 from the non-observability of 0νββ in several medium and heavy open-shell nuclei for different gauge mediated breaking scenarios. In general, they are stronger than those known from other analyses. Also some studies with respect to the future 0νββ projects are presented.
Physical Review C, 2008
We show that, within the Quasiparticle Random Phase Approximation (QRPA) and the renormalized QRP... more We show that, within the Quasiparticle Random Phase Approximation (QRPA) and the renormalized QRPA (RQRPA) based on the Bonn CD nucleon-nucleon interaction, the competition between the pairing and the neutron-proton particle-particle and particle-hole interactions causes contributions to the neutrinoless double-beta decay matrix element to nearly vanish at internucleon distances of more than 2 or 3 fermis. As a result, the matrix element is more sensitive to short-range/highmomentum physics than one naively expects. We analyze various ways of treating that physics and quantify the uncertainty it produces in the matrix elements, with three different treatments of short-range correlations.
Physical Review C, 2004
We study lepton number violating (LNV) process of (µ − , e +) conversion in nuclei mediated by th... more We study lepton number violating (LNV) process of (µ − , e +) conversion in nuclei mediated by the exchange of light and heavy Majorana neutrinos. Nuclear structure calculations have been carried out for the case of experimentally interesting nucleus 48 Ti in the framework of renormalized protonneutron Quasiparticle Random Phase Approximation. We demonstrate that the imaginary part of the amplitude of light Majorana neutrino exchange mechanism gives an appreciable contribution to the (µ − , e +) conversion rate. This specific feature is absent in the allied case of 0νββ decay. Using the present neutrino oscillations, tritium beta decay, accelerator and cosmological data we derived the limits on the effective masses of light m µe and heavy M −1 N µe neutrinos. The expected rates of nuclear (µ − , e +) conversion, corresponding to these limits, were found to be so small that even within a distant future the (µ − , e +) conversion experiments will hardly be able to detect the neutrino signal. Therefore, searches for this LNV process can only rely on the presence of certain physics beyond the trivial extension of the Standard Model by inclusion of massive Majorana neutrinos.
Physical Review C, 2013
0νββ and 2νββ nuclear matrix elements, QRPA, and isospin symmetry restoration FedorŠimkovic *
Journal of the Korean Physical Society, 2008
AIP Conference Proceedings, 2007
A discussion is given on possible realization of the Single State Dominance (SSD) hypothesis in t... more A discussion is given on possible realization of the Single State Dominance (SSD) hypothesis in the case of the two-neutrino double beta decay (2νββ-decay) of 150 N d with 1 − ground state of the intermediate nucleus. We conclude that the SSD hypothesis is expected to be ruled out by precision measurement of differential characteristics of this process in running NEMO 3 or planed SuperNEMO experiments unlike some unknown low-lying 1 + state of 150 P m does exist. This problem can be solved via (d, 2 He) charge-exchange experiment on 150 Sm. Further, we address the question about possible violation of the Pauli exclusion principle for neutrinos and its consequences for the energy distributions of the 2νββ-decay of 150 N d. This phenomenon might be a subject of interest of NEMO 3 and SuperNEMO experiments as well.
AIP Conference Proceedings, 2009
In order to understand the basic nature of the Universe in which we live, we must to understand a... more In order to understand the basic nature of the Universe in which we live, we must to understand and observe relic neutrinos, which evade direct detection so far. For number density of relic neutrinos per flavour< η>= 56 cm− 3 [Giunti and Kim, 2007] a direct ...
The longitudinal form factors of the weak vector current of particles with spin J = 1/2 and isosp... more The longitudinal form factors of the weak vector current of particles with spin J = 1/2 and isospin I = 1/2 are determined by the mass difference and the charge radii of members of the isotopic doublets. The most promising reactions to measure these form factors are the reactions with large momentum transfers involving the spin-1/2 isotopic doublets with a maximum mass splitting. Numerical estimates of longitudinal form factors are given for nucleons and eight nuclear spin-1/2 isotopic doublets.
International Journal of Modern Physics E, 2006
A set of moderately deformed s–d shell nuclei is employed for testing the reliability of the nucl... more A set of moderately deformed s–d shell nuclei is employed for testing the reliability of the nuclear ground state wave functions which are obtained in the context of a BCS approach and offer a simultaneous consideration of deformation and pairing correlations effects. In this method, the mean field is assumed to be an axially symmetric Woods-Saxon potential and the effective two-body interaction is a monopole pairing force. As quantities of main interest we have chosen the nuclear form factors, the occupancies of the active (surface) orbits and the Fermi sea depletion, which provide quite good tests for microscopic descriptions of nuclei within many body theories. For our comparisons with results emerging from other similar methods, an axially deformed harmonic oscillator field is also utilized.
Acta Physica Polonica Series B
We present new formulae for the neutrino masses generated by R-parity violating interactions with... more We present new formulae for the neutrino masses generated by R-parity violating interactions within minimal supersymmetric standard model. The importance of inclusion of CP phases in the neutrino mass matrix is discussed in detail.
In a previous article [Phys. Rev. D 79, 053001 (2009)] we estimated the correlated uncertainties ... more In a previous article [Phys. Rev. D 79, 053001 (2009)] we estimated the correlated uncertainties associated to the nuclear matrix elements (NME) of neutrinoless double beta decay (0νββ) within the quasiparticle random phase approximation (QRPA). Such estimates encompass recent independent calculations of NMEs, and can thus still provide a fair representation of the nuclear model uncertainties. In this context, we compare the claim of 0νββ decay in 76 Ge with recent negative results in 136 Xe and in other nuclei, and we infer the lifetime ranges allowed or excluded at 90% C.L. We also highlight some issues that should be addressed in order to properly compare and combine results coming from different 0νββ candidate nuclei.
International Journal of Modern Physics E, 2006
The presence of trilinear R-parity violating interactions in the MSSM lagrangian leads to existen... more The presence of trilinear R-parity violating interactions in the MSSM lagrangian leads to existence of quark–squark and lepton–slepton loops which generate mass of the neutrino. By introducing interaction with an external photon the magnetic moment is obtained. We derive bounds on that quantity being around one order of magnitude stronger than those present in the literature.
A formal relation between the GT part of the nuclear matrix elements M 0ν GT of 0νβ β decay and t... more A formal relation between the GT part of the nuclear matrix elements M 0ν GT of 0νβ β decay and the closure matrix elements M 2ν cl of 2νβ β decay is established. This relation is based on the integral representation of these quantities in terms of their dependence on the distance r between the two nucleons undergoing transformation. We also discuss the difficulties in determining the correct values of the closure 2νβ β decay matrix elements.
We have performed a critical analysis of different approximation schemes for the calculation of t... more We have performed a critical analysis of different approximation schemes for the calculation of two-neutrino double beta decay (TNDBD) matrix elements. We have shown that within the single-particle approximation of nuclear Hamiltonian the TNDBD matrix element is equal to zero. The (renormalized) quasiboson approximation scheme imply for TNDBD transition operator to be a constant, if one requires the equivalence of initial and final (renormalized) QRPA Hamiltonians. It means that TNDBD is a higher order process in the boson expansion of the nuclear Hamiltonian. We have found that the mismatching of both Hamiltonians is getting worse with increasing strength of particle- particle interaction especially in the case of QRPA Hamiltonians. It is supposed to be one of the reasons of the extreme sensitivity of studied matrix element to the residual interaction appearing in explicit calculations involving the intermediate nucleus. Further, the Operator Expansion Method (OEM) has been reconsi...
In view of recent great progress achieved in the experimental study of the neutrinoless double be... more In view of recent great progress achieved in the experimental study of the neutrinoless double beta decay (0nbb-decay) of 134Xe we discuss theoretical aspects of this process. The light and heavy Majorana neutrino exchange as well as the trilinear R-parity breaking contributions to 0nbb-decay are considered. We show that the sensitivity of the studied process to the signal of lepton number violation is only by factor 2-3 weaker in comparison with the 0nbb-decay of 136Xe. The current limits on effective neutrino mass (light and heavy) and trilinear R-parity violating parameter lambda'_111 deduced from lower limits on the 0nbb-decay half-lifes of various nuclei are reviewed and perspectives of the experimental verification of recently announced evidence of the 0nbb-decay of 76Ge are discussed.
Physical Review D, 2006
The transition magnetic moments of Majorana neutrinos µν ij (ij = eµ, eτ, µτ) are calculated in g... more The transition magnetic moments of Majorana neutrinos µν ij (ij = eµ, eτ, µτ) are calculated in grand unified theory (GUT) constrained Minimal Supersymmetric Standard Model (MSSM) with explicit R-parity violation. It is assumed that neutrinos acquire masses via one-loop (quark-squark and lepton-slepton) radiative corrections. The mixing of squarks, sleptons, and quarks is considered explicitly. The connection between µν ij and the entries of neutrino mass matrix is studied. The current upper limits on µν ij are deduced from the elements of phenomenological neutrino mass matrix, which is reconstructed using the neutrino oscillation data and the lower bound on the neutrinoless double beta decay half-life. Further, the results for µν eµ , µν eτ and µν µτ are presented for the cases of inverted and normal hierarchy of neutrino masses and different SUSY scenarios. The largest values are of the order of 10 −17 in units of Bohr magneton.
Physical Review D, 2008
At the quark level there are basically two types of contributions of R-parity violating SUSY (Rp ... more At the quark level there are basically two types of contributions of R-parity violating SUSY (Rp / SUSY) to neutrinoless double beta decay: the short-range contribution involving only heavy virtual superpartners and the long-range one with the virtual squark and neutrino. Hadronization of the effective operators, corresponding to these two types of contributions, may in general involve virtual pions in addition to close on-mass-shell nucleons. From the previous studies it is known that the short-range contribution is dominated by the pion exchange. In the present paper we show that this is also true for the long-range Rp / SUSY contribution. Therefore, we conclude that the Rp / SUSY contributes to the neutrinoless double beta decay dominantly via charged pion exchange between the decaying nucleons.
Physical Review D, 2004
We study nuclear µ − − e − conversion in the general framework of an effective Lagrangian approac... more We study nuclear µ − − e − conversion in the general framework of an effective Lagrangian approach without referring to any specific realization of the physics beyond the standard model (SM) responsible for lepton flavor violation (L f /). We examine the impact of a specific hadronization prescription on the analysis of new physics in nuclear µ − −e − conversion and stress the importance of vector meson exchange between lepton and nucleon currents. A new issue of this mechanism is the presence of the strange quark vector current contribution induced by the φ meson. This allows us to extract new limits on the L f / lepton-quark effective couplings from the existing experimental data.
Physical Review D, 1998
We discuss some phenomenological issues of the effective quarklepton operators emerging from the ... more We discuss some phenomenological issues of the effective quarklepton operators emerging from the bilinear lepton-Higgs couplings in the superpotential and in the soft supersymmetry (SUSY) breaking sector of the supersymmetric models without R-parity. The contribution of these operators to the neutrinoless double beta decay (0νββ) is derived. The corresponding nuclear matrix elements are calculated within the renormalized quasiparticle random phase approximation, which includes the Pauli effect of fermion pairs and does not collapse for the physical values of the nuclear force strength. On this basis we extract from the experimental data new stringent limits on the 1st generation mass parameter characterized the lepton-Higgs bilinear coupling and on the electron sneutrino vacuum expectation value.
Physical Review C, 2004
The Minimal Supersymmetric Standard Model with gauge mediated supersymmetry breaking and trilinea... more The Minimal Supersymmetric Standard Model with gauge mediated supersymmetry breaking and trilinear R-parity violation is applied to the description of neutrinoless double beta decay. A detailed study of limits on the parameter space coming from the B → Xsγ processes by using the recent CLEO results is performed. The importance of two-nucleon and pion-exchange realizations of 0νββ decay together with gluino and neutralino contributions to this process are addressed. We have deduced new limits on the trilinear R-parity breaking parameter λ ′ 111 from the non-observability of 0νββ in several medium and heavy open-shell nuclei for different gauge mediated breaking scenarios. In general, they are stronger than those known from other analyses. Also some studies with respect to the future 0νββ projects are presented.
Physical Review C, 2008
We show that, within the Quasiparticle Random Phase Approximation (QRPA) and the renormalized QRP... more We show that, within the Quasiparticle Random Phase Approximation (QRPA) and the renormalized QRPA (RQRPA) based on the Bonn CD nucleon-nucleon interaction, the competition between the pairing and the neutron-proton particle-particle and particle-hole interactions causes contributions to the neutrinoless double-beta decay matrix element to nearly vanish at internucleon distances of more than 2 or 3 fermis. As a result, the matrix element is more sensitive to short-range/highmomentum physics than one naively expects. We analyze various ways of treating that physics and quantify the uncertainty it produces in the matrix elements, with three different treatments of short-range correlations.
Physical Review C, 2004
We study lepton number violating (LNV) process of (µ − , e +) conversion in nuclei mediated by th... more We study lepton number violating (LNV) process of (µ − , e +) conversion in nuclei mediated by the exchange of light and heavy Majorana neutrinos. Nuclear structure calculations have been carried out for the case of experimentally interesting nucleus 48 Ti in the framework of renormalized protonneutron Quasiparticle Random Phase Approximation. We demonstrate that the imaginary part of the amplitude of light Majorana neutrino exchange mechanism gives an appreciable contribution to the (µ − , e +) conversion rate. This specific feature is absent in the allied case of 0νββ decay. Using the present neutrino oscillations, tritium beta decay, accelerator and cosmological data we derived the limits on the effective masses of light m µe and heavy M −1 N µe neutrinos. The expected rates of nuclear (µ − , e +) conversion, corresponding to these limits, were found to be so small that even within a distant future the (µ − , e +) conversion experiments will hardly be able to detect the neutrino signal. Therefore, searches for this LNV process can only rely on the presence of certain physics beyond the trivial extension of the Standard Model by inclusion of massive Majorana neutrinos.
Physical Review C, 2013
0νββ and 2νββ nuclear matrix elements, QRPA, and isospin symmetry restoration FedorŠimkovic *