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J. Marton

Publications and source records attributed to J. Marton.

At least 91 records · Page 5Linked to original sources
arXiv2011

Molecule model for deeply bound and broad kaonic nuclear clusters

A molecule model is proposed for the description of the properties of the kaonic nuclear cluster (KNC) anti-KNN with the structure N(ant-KN)_(I = 0) and quantum numbers I(J^P) = 1/2(0^-), the large binding energy B^(\exp)_(anti-KNN) = 103(6) MeV and the width Gamma^(\exp)_(anti-KNN) = 118(13) MeV, observed recently by the DISTO Collaboration. The theoretical values of the binding energy B^(th)_(anti-KNN) = 118 MeV, the width Gamma^(th)_(anti-KNN) = 142 MeV of the KNC anti-KNN and the density n_(anti-KNN) = 2.71 n_0, where n_0= 0.17 fm^(-3) is the normal nuclear density, reproduce well the large experimental values. They are calculated with the trial harmonic oscillator wave functions by using chiral Lagrangians, accounting for all self-energy terms, contributing to the masses of the kaonic nuclear clusters (anti-KN)_(I = 0) and anti-KNN. In addition the high Lambda*p sticking probability in the pp reaction at the kinetic energy T_p = 2.85 GeV of the incident proton is explained.

nucl-th↗
arXiv2011

First measurement of kaonic helium-3 X-rays

The first observation of the kaonic 3He 3d - 2p transition was made using slow K- mesons stopped in a gaseous 3He target. The kaonic atom X-rays were detected with large-area silicon drift detectors using the timing information of the K+K- pairs of phi-meson decays produced by the DAFNE e+e- collider. The strong interaction shift of the kaonic 3He 2p state was determined to be -2+-2 (stat)+-4 (syst) eV.

nucl-ex↗
arXiv2010

Molecule model for kaonic nuclear cluster anti-KNN

We analyse the properties of the kaonic nuclear cluster (KNC) anti-KNN with the structure Nx(anti-KN)_(I = 0), having the quantum numbers I(J^P) = 1/2(0^-), and treated as a quasi-bound hadronic molecule state. We describe the properties of the hadronic molecule, or the KNC Nx(anti-KN)_(I = 0), in terms of vibrational degrees of freedom with oscillator wave functions and chiral dynamics. These wave functions, having the meaning of trial wave functions of variational calculations, are parameterised by the frequency of oscillations of the (anti-KN)_(I = 0) pair, which is fixed in terms of the binding energy of the strange baryon resonance Lambda(1405), treated as a quasi-bound (anti-KN)_(I = 0) state. The binding energies B_X and widths Gamma_X of the states X = (anti-KN)_(I = 0) and X = anti-KNN, respectively, are calculated in the heavy-baryon approximation by using chiral Lagrangians with meson-baryon derivative couplings invariant under chiral SU(3)xSU(3) symmetry at the tree-level approximation. The results are B_(anti-KNN) = 40.2 MeV and Gamma_(anti-KNN) = Gamma^(non-pionic)_(anti-KNN) + Gamma^(pionic)_(anti-KNN) ~ (85 - 106) MeV and, where Gamma^(non-pionic)_(anti-KNN) ~ 21 MeV and Gamma^(pionic)_(anti-KNN) ~ (64 - 86) MeV are the widths of non-pionic anti-KNN -> N Lambda^0, N Sigma and pionic anti-KNN -> N Sigma pi decay modes, calculated for B_(anti-KN) = 29 MeV and Gamma_(anti-KN) = (30 - 40) MeV, respectively.

nucl-th↗
arXiv2010

The PANDA GEM-based TPC Prototype

We report on the development of a GEM-based TPC prototype for the PANDA experiment. The design and requirements of this device will be illustrated, with particular emphasis on the properties of the recently tested GEM-detector, the characterization of the read-out electronics and the development of the tracking software that allows to evaluate the GEM-TPC data.

nucl-ex↗
arXiv2010

Study of timing performance of Silicon Photomultiplier and application for a Cherenkov detector

Silicon photomultipliers are very versatile photo detectors due to their high photon detection efficiency, fast response, single photon counting capability, high amplification, and their insensitivity to magnetic fields. At our institute we are studying the performance of these photo detectors at various operating conditions. On the basis of the experience in the laboratory we built a prototype of a timing Cherenkov detector consisting of a quartz radiator with two $3\times 3$ mm$^2$ MPPCs S10362-33-100C from Hamamatsu Photonics as photodetectors. The MPPC sensors were operated with Peltier cooling to minimize thermal noise and to avoid gain drifts. The test measurements at the DA$Φ$NE Beam-Test Facility (BTF) at the Laboratori Nazionali di Frascati (LNF) with pulsed 490 MeV electrons and the results on timing performance with Cherenkov photons are presented.

nucl-ex↗
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

Measurement of the in-medium K0 inclusive cross section in pi- -induced reactions at 1.15 GeV/c

The K0 meson production by pi- mesons of 1.15 GeV/c momentum on C, Al, Cu, Sn and Pb nuclear targets was measured with the FOPI spectrometer at the SIS accelerator of GSI. Inclusive production cross-sections and the momentum distributions of K0 mesons are compared to scaled elementary production cross-sections and to predictions of theoretical models describing the in-medium production of kaons. The data represent a new reference for those models, which are widely used for interpretation of the strangeness-production in heavy-ion collisions. The presented results demonstrate the sensitivity of the kaon production to the reaction amplitudes inside nuclei and point to the existence of a repulsive KN-potential of 20+-5 MeV at normal nuclear matter density.

nucl-ex↗
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

Improved Study of the Antiprotonic Helium Hyperfine Structure

We report the initial results from a systematic study of the hyperfine (HF) structure of antiprotonic helium (n,l) = (37,~35) carried out at the Antiproton Decelerator (AD) at CERN. We performed a laser-microwave-laser resonance spectroscopy using a continuous wave (cw) pulse-amplified laser system and microwave cavity to measure the HF transition frequencies. Improvements in the spectral linewidth and stability of our laser system have increased the precision of these measurements by a factor of five and reduced the line width by a factor of three compared to our previous results. A comparison of the experimentally measured transition frequencies with three body QED calculations can be used to determine the antiproton spin magnetic moment, leading towards a test of CPT invariance.

physics.atom-ph↗
arXiv2008

New experimental limit on Pauli Exclusion Principle violation by electrons (the VIP experiment)

The Pauli Exclusion Principle is one of the basic principles of modern physics and is at the very basis of our understanding of matter: thus it is fundamental importance to test the limits of its validity. Here we present the VIP (Violation of the Pauli Exclusion Principle) experiment, where we search for anomalous X-rays emitted by copper atoms in a conductor: any detection of these anomalous X-rays would mark a Pauli-forbidden transition. ] VIP is currently taking data at the Gran Sasso underground laboratories, and its scientific goal is to improve by at least four orders of magnitude the previous limit on the probability of Pauli violating transitions, bringing it into the 10**-29 - 10**-30 region. First experimental results, together with future plans, are presented.

quant-ph↗
arXiv2007

Precision measurement of the $3d \to 2p$ x-ray energy in kaonic $^4$He

We have measured the Balmer-series x-rays of kaonic $^4$He atoms using novel large-area silicon drift x-ray detectors in order to study the low-energy $\bar{K}$-nucleus strong interaction. The energy of the $3d \to 2p$ transition was determined to be 6467 $\pm$ 3 (stat) $\pm$ 2 (syst) eV. The resulting strong-interaction energy-level shift is in agreement with theoretical calculations, thus eliminating a long-standing discrepancy between theory and experiment.

nucl-ex↗
arXiv2007

Precision X-ray measurements on kaonic atoms at LNF

After the successfully performed DEAR experiment at DAFNE - resulting in the most precise data on the hadronic shift and width in kaonic hydrogen up-to-now - the next step will be the measurement at the percent level using new X-ray detectors. These detectors (silicon drift detectors) are developed within the SIDDHARTA project. The asynchronous background will be suppressed using the time correlation between the kaon and the X-ray by 2-3 orders of magnitude. These measurements will lead to precise values of the isospin-dependent antikaon-nucleon scattering lengths, thus opening a new insight in the low-energy kaon nucleon interaction.

nucl-ex↗
arXiv2006

New experimental limit on Pauli Exclusion Principle violation by electrons (the VIP experiment)

The Pauli exclusion principle (PEP) represents one of the basic principles of modern physics and, even if there are no compelling reasons to doubt its validity, it still spurs a lively debate, because an intuitive, elementary explanation is still missing, and because of its unique stand among the basic symmetries of physics. A new limit on the probability that PEP is violated by electrons was estabilished by the VIP (VIolation of the Pauli exclusion principle) Collaboration, using the method of searching for PEP forbidden atomic transitions in copper. The preliminary value, ${1/2}β^{2} \textless 4.5\times 10^{-28}$, represents an improvement of about two orders of magnitude of the previous limit. The goal of VIP is to push this limit at the level of $10^{-30}$.

quant-ph↗
arXiv2006

Phenomenological model of the Kaonic Nuclear Cluster K^-pnn in the ground state

A phenomenological model, proposed for the Kaonic Nuclear Cluster (KNC) K^-pp, is applied to the theoretical analysis of the KNC K^-pnn (or S^0). The theoretical values of the binding energy and the width are equal to epsilon_(S^0) = - 197 MeV and Gamma_(S^0) = 16 MeV. They agree well with the experimental data epsilon^(exp)_(S^0) = - 194.0(+ 1.5/- 4.4) MeV and Gamma^(exp)_(S^0) < 21 MeV} (PLB 597, 263 (2004)) and the theoretical values epsilon_(S^0) = - 191 MeV and Gamma_(S^0) = 13 MeV, obtained by Akaishi and Yamazaki within the potential model approach.

nucl-th↗
arXiv2006

Phenomenological model of the Kaonic Nuclear Cluster K^-pp in the ground state

A phenomenological model is proposed for the analysis of the properties of the Kaonic Nuclear Cluster (KNC) Kpp in its ground state. Inside the KNC K^-pp we describe the relative motion of the protons in the pp pair and the motion of the K^- meson relative to the pp pair in terms of wave functions of 3-dimensional harmonic oscillators. The interaction strength is parameterised in our model by the frequency of the longitudinal oscillation of the K^- meson relative to the pp pair. This parameter was determined with the binding energy and width of the strange baryon Lambda(1405) by assuming that it is a bound state of the K^-p pair. In terms of this interaction strength we calculate the binding energy epsilon_(Kpp) = - 118 MeV, the partial widths of non-pionic decay channels and the total width, Gamma_(Kpp) = 58 MeV. This agrees well with the experimental data by the FINUDA Collaboration (PRL 94, 212303 (2005)): epsilon_exp = - 115(+6/-5) MeV and Gamma_exp = 67(+14/-11) MeV. The discrepancy with the results, obtained by Akaishi and Yamazaki within the potential model approach, is discussed.

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.

nucl-th↗