The Experts below are selected from a list of 204 Experts worldwide ranked by ideXlab platform
V V Ignatyuk - One of the best experts on this subject based on the ideXlab platform.
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a temperature behavior of the frustrated translational mode of adsorbate and the nature of the adsorbate substrate interaction
Journal of Chemical Physics, 2012Co-Authors: V V IgnatyukAbstract:A temperature behavior of the frustrated translational mode (T-mode) of a Light Particle, coupled by different regimes of ohmicity to the surface, is studied within a formalism of the generalized diffusion coefficients. The memory effects of the adsorbate motion are considered to be the main reason of the T-mode origin. Numerical calculations yield a thermally induced shift and broadening of the T-mode, which is found to be linear in temperature for Ohmic and super-Ohmic systems and nonlinear for strongly sub-Ohmic ones. We obtain analytical expressions for the T-mode shift and width at weak coupling for the systems with integer “ohmicity” indexes n = 0÷2 in zero temperature and high temperature limits. We provide an explanation of the experimentally observed blue- or redshifts of the T-mode on the basis of a comparative analysis of two typical times of the system evolution: a time of decay of the “velocity–velocity” autocorrelation function, and a correlation time of the thermal bath random forces. A rel...
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a temperature behavior of the frustrated translational mode of adsorbate and the nature of the adsorbate substrate interaction
arXiv: Statistical Mechanics, 2012Co-Authors: V V IgnatyukAbstract:A temperature behavior of the frustrated translational mode (T-mode) of a Light Particle, coupled by different regimes of ohmicity to the surface, is studied within a formalism of the generalized diffusion coefficients. The memory effects of the adsorbate motion are considered to be the main reason of the T-mode origin. Numerical calculations yield a thermally induced shift and broadening of the T-mode, which is found to be linear in temperature for Ohmic and super-Ohmic systems and nonlinear for strongly sub-Ohmic ones. We obtain analytical expressions for the T-mode shift and width at weak coupling for the systems with integer "ohmicity" indexes n=0-2 in zero temperature and high temperature limits. We provide an explanation of the experimentally observed blue- or red-shifts of the T-mode on the basis of a comparative analysis of two typical times of the system evolution: a time of decay of the "velocity-velocity" autocorrelation function, and a correlation time of the thermal bath random forces. A relation of the T-mode to the multiple jumps of the adsorbate is discussed, and generalization of conditions of the multiple hopping to the case of quantum surface diffusion is performed.
C Chiri - One of the best experts on this subject based on the ideXlab platform.
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search for lepton flavour violating muon decay mediated by a new Light Particle in the meg experiment
European Physical Journal C, 2020Co-Authors: A M Baldini, F Berg, M Biasotti, G Boca, P W Cattaneo, G Cavoto, F Cei, M Chiappini, G Chiarello, C ChiriAbstract:Recently, in elementary Particle physics research, exploring new physics beyond the stan-dard model has been actively conducted. However, there is no clear evidence of such anew physics to date but of some anomalies. To tackle this situation, we have searched forlepton flavor violating muon decay mediated by a new Light Particle. The charged lepton flavorviolation is one of the powerful tools to search for new physics beyond the standard model. On theother hand, Light new physics has attracted a great deal of attention. In the analysis performedin this thesis, we combined these directions and have searched for theμ+→e+X,X→γγdecayusing the full datasets (2009–2013) of the MEG experiment.The MEG experiment was designed to search for lepton flavor violating muon decay,μ+→e+γ, not forμ+→e+X,X→γγ. However, we made full use of the resources developed for theμ+→e+γsearch. We have newly developed reconstruction methods and dedicated corrections fortheμ+→e+X,X→γγsearch. The search analysis has been completely renewed; we combinedblind, cut-counting, and maximum likelihood analysis. The full datasets of the MEG experiment,which corresponds to 7.5×1014μ+s decay on the target, were analyzed. No significant excess wasfound in the mass region of 20–45 MeV, lifetime below 40 ps. Thus, we set the most stringentbranching ratio upper limits in the mass region of 20–40 MeV. Especially, upper limits are pusheddown to the level ofO(10−11) for 20–30 MeV.It is at most 60 times stringent result than the bound converted from the previous experiment,the Crystal Box experiment. Together with the previous analysis using the first-two-year (2009and 2010) physics data of the MEG experiment, this is the first direct search of theμ+→e+X,X→γγdecay in the world.
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search for lepton flavour violating muon decay mediated by a new Light Particle in the meg experiment
arXiv: High Energy Physics - Experiment, 2020Co-Authors: A M Baldini, F Berg, M Biasotti, G Boca, P W Cattaneo, G Cavoto, F Cei, M Chiappini, G Chiarello, C ChiriAbstract:We present the first direct search for lepton flavour violating muon decay mediated by a new Light Particle X, $\mu^+ \to \mathrm{e}^+\mathrm{X}, \mathrm{X} \to \gamma\gamma$. This search uses a dataset resulting from $7.5\times 10^{14}$ stopped muons collected by the MEG experiment at the Paul Scherrer Institut in the period 2009--2013. No significant excess is found in the mass region 20--45 MeV/c$^2$ for lifetimes below 40 ps, and we set the most stringent branching ratio upper limits in the mass region of 20--40 MeV/c$^2$, down to $\mathcal{O}(10^{-11})$ at 90\% confidence level.
Arghavan Safavinaini - One of the best experts on this subject based on the ideXlab platform.
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nonuniversal bound states of two identical heavy fermions and one Light Particle
Physical Review A, 2013Co-Authors: Arghavan Safavinaini, Seth T Rittenhouse, D Blume, H R SadeghpourAbstract:We study the behavior of the bound-state energy of a system consisting of two identical heavy fermions of mass M and a Light Particle of mass m. The heavy fermions interact with the Light Particle through a short-range two-body potential with positive s-wave scattering length a. We impose a short-range boundary condition on the logarithmic derivative of the hyperradial wave function and show that, in the regime where Efimov states are absent, a nonuniversal three-body state cuts through the universal three-body states previously described by Kartavtsev and Malykh. The presence of the nonuniversal state alters the behavior of the universal states in certain regions of the parameter space. We show that the existence of the nonuniversal state is predicted accurately by a simple quantum defect theory model that utilizes hyperspherical coordinates. An empirical two-state model is employed to quantify the coupling of the nonuniversal state to the universal states.
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nonuniversal bound states of two identical heavy fermions and one Light Particle
Physical Review Letters, 2013Co-Authors: Arghavan Safavinaini, Seth T Rittenhouse, D Blume, H R SadeghpourAbstract:We study the behavior of the bound state energy of a system consisting of two identical heavy fermions of massM and a Light Particle of massm. The heavy fermions interact with the Light Particle through a short-range two-body potential with positive s-wave scattering length as. We impose a short-range boundary condition on the logarithmic derivative of the hyperradial wavefunction and show that, in the regime where Emov states are absent, a non-universal three-body state \cuts through" the universal three-body states previously described by Kartavtsev and Malykh [O. I. Kartavtsev and A. V. Malykh, J. Phys. B 40, 1429 (2007)]. The presence of the non-universal state alters the behavior of the universal states in certain regions of the parameter space. We show that the existence of the non-universal state is predicted accurately by a simple quantum defect theory model that utilizes hyperspherical coordinates. An empirical two-state model is employed to quantify the coupling of the non-universal state to the universal states.
A M Baldini - One of the best experts on this subject based on the ideXlab platform.
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search for lepton flavour violating muon decay mediated by a new Light Particle in the meg experiment
European Physical Journal C, 2020Co-Authors: A M Baldini, F Berg, M Biasotti, G Boca, P W Cattaneo, G Cavoto, F Cei, M Chiappini, G Chiarello, C ChiriAbstract:Recently, in elementary Particle physics research, exploring new physics beyond the stan-dard model has been actively conducted. However, there is no clear evidence of such anew physics to date but of some anomalies. To tackle this situation, we have searched forlepton flavor violating muon decay mediated by a new Light Particle. The charged lepton flavorviolation is one of the powerful tools to search for new physics beyond the standard model. On theother hand, Light new physics has attracted a great deal of attention. In the analysis performedin this thesis, we combined these directions and have searched for theμ+→e+X,X→γγdecayusing the full datasets (2009–2013) of the MEG experiment.The MEG experiment was designed to search for lepton flavor violating muon decay,μ+→e+γ, not forμ+→e+X,X→γγ. However, we made full use of the resources developed for theμ+→e+γsearch. We have newly developed reconstruction methods and dedicated corrections fortheμ+→e+X,X→γγsearch. The search analysis has been completely renewed; we combinedblind, cut-counting, and maximum likelihood analysis. The full datasets of the MEG experiment,which corresponds to 7.5×1014μ+s decay on the target, were analyzed. No significant excess wasfound in the mass region of 20–45 MeV, lifetime below 40 ps. Thus, we set the most stringentbranching ratio upper limits in the mass region of 20–40 MeV. Especially, upper limits are pusheddown to the level ofO(10−11) for 20–30 MeV.It is at most 60 times stringent result than the bound converted from the previous experiment,the Crystal Box experiment. Together with the previous analysis using the first-two-year (2009and 2010) physics data of the MEG experiment, this is the first direct search of theμ+→e+X,X→γγdecay in the world.
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search for lepton flavour violating muon decay mediated by a new Light Particle in the meg experiment
arXiv: High Energy Physics - Experiment, 2020Co-Authors: A M Baldini, F Berg, M Biasotti, G Boca, P W Cattaneo, G Cavoto, F Cei, M Chiappini, G Chiarello, C ChiriAbstract:We present the first direct search for lepton flavour violating muon decay mediated by a new Light Particle X, $\mu^+ \to \mathrm{e}^+\mathrm{X}, \mathrm{X} \to \gamma\gamma$. This search uses a dataset resulting from $7.5\times 10^{14}$ stopped muons collected by the MEG experiment at the Paul Scherrer Institut in the period 2009--2013. No significant excess is found in the mass region 20--45 MeV/c$^2$ for lifetimes below 40 ps, and we set the most stringent branching ratio upper limits in the mass region of 20--40 MeV/c$^2$, down to $\mathcal{O}(10^{-11})$ at 90\% confidence level.
H R Sadeghpour - One of the best experts on this subject based on the ideXlab platform.
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nonuniversal bound states of two identical heavy fermions and one Light Particle
Physical Review A, 2013Co-Authors: Arghavan Safavinaini, Seth T Rittenhouse, D Blume, H R SadeghpourAbstract:We study the behavior of the bound-state energy of a system consisting of two identical heavy fermions of mass M and a Light Particle of mass m. The heavy fermions interact with the Light Particle through a short-range two-body potential with positive s-wave scattering length a. We impose a short-range boundary condition on the logarithmic derivative of the hyperradial wave function and show that, in the regime where Efimov states are absent, a nonuniversal three-body state cuts through the universal three-body states previously described by Kartavtsev and Malykh. The presence of the nonuniversal state alters the behavior of the universal states in certain regions of the parameter space. We show that the existence of the nonuniversal state is predicted accurately by a simple quantum defect theory model that utilizes hyperspherical coordinates. An empirical two-state model is employed to quantify the coupling of the nonuniversal state to the universal states.
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nonuniversal bound states of two identical heavy fermions and one Light Particle
Physical Review Letters, 2013Co-Authors: Arghavan Safavinaini, Seth T Rittenhouse, D Blume, H R SadeghpourAbstract:We study the behavior of the bound state energy of a system consisting of two identical heavy fermions of massM and a Light Particle of massm. The heavy fermions interact with the Light Particle through a short-range two-body potential with positive s-wave scattering length as. We impose a short-range boundary condition on the logarithmic derivative of the hyperradial wavefunction and show that, in the regime where Emov states are absent, a non-universal three-body state \cuts through" the universal three-body states previously described by Kartavtsev and Malykh [O. I. Kartavtsev and A. V. Malykh, J. Phys. B 40, 1429 (2007)]. The presence of the non-universal state alters the behavior of the universal states in certain regions of the parameter space. We show that the existence of the non-universal state is predicted accurately by a simple quantum defect theory model that utilizes hyperspherical coordinates. An empirical two-state model is employed to quantify the coupling of the non-universal state to the universal states.
