Search

Strong interaction energy shifts and widths in kaonic atoms are calculated for the first time using microscopic $K^- N$ + $K^- NN$ potentials derived from $K^- N$ scattering amplitudes constructed within SU(3) chiral coupled-channels models of meson-baryon interactions. The in-medium modifications of the free-space amplitudes due to the Pauli correlations are taken into account. The $K^-N+K^-NN$ potentials evaluated for 23 nuclear species are confronted with kaonic atoms data. The description of the data significantly improves when the $K^-NN$ absorption is included. To get $\chi^2$ as low as for the $K^-N+$phenomenological multi-nucleon potential an additional phenomenological term, accounting for $K^{-}-3N(4N)$ processes, is still needed. However, density dependence of this phenomenological term points out some deficiencies in the microscopic potentials and further improvements of the applied model are thus desirable. The calculated branching ratios for $K^-N$ and $K^-NN$ absorption channels in the $^{12}$C$+K^-$ atom are in reasonable agreement with the old bubble chamber data, as well as with the latest data from the AMADEUS Collaboration., Comment: 24 pages, 7 figures, 7 tables

Consequences of increasing the binding energy of the hypertriton ground state ${_{\Lambda}^3}{\rm H}(J^P={\frac{1}{2}}^+)$ from the emulsion value $B^{\rm EMUL}_{\Lambda}({_{\Lambda}^3}{\rm H}_{\rm g.s.})$=0.13$\pm$0.05 MeV to the STAR value $B^{\rm STAR}_{\Lambda}(^{3}_{\Lambda}{\rm H}) = (0.41\pm 0.12 \pm 0.11)$ MeV are studied for $s$-shell hypernuclei within a pionless EFT approach at leading order, constrained by the binding energies of the $0^+$ and $1^+$ ${_{\Lambda}^4} {\rm H}$ states. The stochastic variational method is used in bound-state calculations, whereas the inverse analytic continuation in the coupling constant method is used to locate $S$-matrix poles of continuum states. It is found that the $\Lambda nn({\frac{1}{2}}^+)$ resonance becomes broader and less likely to be observed experimentally, whereas the ${_{\Lambda}^3}{\rm H}({\frac{3}{2}}^+)$ spin-flip virtual state moves closer to the $\Lambda d$ threshold to become a shallow bound state for specific $\Lambda N$ interaction strengths. The effect of such a near-threshold ${_{\Lambda}^3}{\rm H}({\frac{3}{2}}^+)$ state on femtoscopic studies of $\Lambda$-deuteron correlations, and its lifetime if bound, are discussed. Increasing $B_{\Lambda}({_{\Lambda}^3} {\rm H}_{\rm g.s.})$ moderately, up to $\sim$0.5 MeV, hardly affects calculated values of $B_{\Lambda}({_{\Lambda}^5}{\rm He})$.

The nature of the $\Lambda nn$ and ${\rm ^3_\Lambda H^*} (J^\pi=3/2^+,~I=0)$ states is investigated within a pionless effective field theory at leading order, constrained by the low energy $\Lambda N$ scattering data and hypernuclear 3- and 4-body data. Bound state solutions are obtained using the stochastic variational method, the continuum region is studied by employing two independent methods - the inverse analytic continuation in the coupling constant method and the complex scaling method. Our calculations yield both the $\Lambda nn$ and ${\rm ^3_\Lambda H^*}$ states unbound. We conclude that the excited state ${\rm ^3_\Lambda H^*}$ is a virtual state and the $\Lambda nn$ pole located close to the three-body threshold in a complex energy plane could convert to a true resonance with Re$(E)>0$ for some considered $\Lambda N$ interactions. Finally, the stability of resonance solutions is discussed and limits of the accuracy of performed calculations are assessed.

We performed calculations of nuclear systems composed solely of $\Lambda^*$ hyperons, aiming at exploring the possibility of existence of absolutely stable $\Lambda^*$ matter. We considered $\Lambda^*$ interaction strengths compatible with the $\Lambda^*\Lambda^*$ binding energy $B_{\Lambda^*\Lambda^*}$ given by the $\bar{K}N$ interaction model by Yamazaki and Akaishi [1]. We found that the binding energy per $\Lambda^*$ saturates at values well below 100 MeV for mass number $A\geq120$. The $\Lambda^*$ matter is thus highly unstable against strong interaction decay., Comment: Proceedings of HADRON2019, 16 - 21 August 2019, Guilin, China, to appear in International Journal of Modern Physics A

The spectrum of hypernuclear trios composed of a $\Lambda$ baryon and two nucleons is the subject of an ongoing experimental campaign, aiming to study the interaction of the $\Lambda$ particle with a neutron, and the 3-body $\Lambda$-nucleon-nucleon force. In this manuscript we utilize baryonic effective field theory at leading order, constrained to reproduce the available low energy light hypernuclear data, to study the continuum spectrum of such hypernuclear trios. Using the complex scaling method and the inverse analytic continuation in the coupling constant method we find the existence of a virtual state in the $\Lambda n p$ $J^{\pi}=\frac{3}{2}^{+}$ channel, leading to cross-section enhancement near threshold. For the $\Lambda n n$ $J^{\pi}=\frac{1}{2}^{+}$ channel we predict a resonance state. Depending, however, on the value of the $\Lambda N$ scattering length, the resonance pole moves from the physical to the unphysical complex energy sheet within the experimental bounds., Comment: 8 pages, 4 figures

Binding energies of light, $A\leq 6$, $\Lambda\Lambda$ hypernuclei are calculated using the stochastic variational method in a pionless effective field theory (EFT) approach at leading order with the purpose of assessing critically the onset of binding in the strangeness S=-2 hadronic sector. The EFT input in this sector consists of (i) a $\Lambda\Lambda$ contact term constrained by the $\Lambda\Lambda$ scattering length $a_{\Lambda\Lambda}$, using a range of values compatible with $\Lambda\Lambda$ correlations observed in relativistic heavy ion collisions, and (ii) a $\Lambda\Lambda N$ contact term constrained by the only available $A\leq 6$ $\Lambda\Lambda$ hypernucler binding energy datum of $^{6}_{\Lambda\Lambda}$He. The recently debated neutral three-body and four-body systems $^{3}_{\Lambda\Lambda}$n and $^{4}_{\Lambda\Lambda}$n are found unbound by a wide margin. A relatively large value of $|a_{\Lambda\Lambda}| \gtrsim 1.5$ fm is needed to bind $^{4}_{\Lambda\Lambda}$H, thereby questioning its particle stability. In contrast, the particle stability of the $A=5$ $\Lambda\Lambda$ hypernuclear isodoublet $^{5}_{\Lambda\Lambda} $H--$^{5}_{\Lambda\Lambda}$He is robust, with $\Lambda$ separation energy of order 1 MeV., Comment: v2 -- 14 pages, 4 figures, 1 table, slightly revised, accepted for publication in PLB

A hypothesis of absolutely stable strange hadronic matter composed of $\Lambda(1405)$ baryons, here denoted $\Lambda^*$, is tested within many-body calculations performed using the Relativistic Mean-Field approach. In our calculations, we employed the $\Lambda^*\Lambda^*$ interaction compatible with the $\Lambda^*\Lambda^*$ binding energy $B_{\Lambda^*\Lambda^*}=40$~MeV given by the phenomenological energy-independent $\bar{K}N$ interaction model by Yamazaki and Akaishi (YA). We found that the binding energy per $\Lambda^*$, as well as the central density in $\Lambda^*$ many-body systems saturates for mass number $A\geq120$, leaving $\Lambda^*$ aggregates highly unstable against strong interaction decay. Moreover, we confronted the YA interaction model with kaonic atom data and found that it fails to reproduce the $K^-$ single-nucleon absorption fractions at rest from bubble chamber experiments., Comment: Proceedings of the HYP2018 conference, Norfolk/Portsmouth, USA, June 24 - 29, 2018, submitted to AIP Conference Proceedings

In this contribution we report on theoretical studies of $\eta$ nuclear quasi-bound states in few- and many-body systems performed recently by the Jerusalem-Prague Collaboration [1-5]. Underlying energy-dependent $\eta N$ interactions are derived from coupled-channel models that incorporate the $N^*(1535)$ resonance. The role of self-consistent treatment of the strong energy dependence of subthreshold $\eta N$ amplitudes is discussed. Quite large downward energy shift together with rapid decrease of the $\eta N$ amplitudes below threshold result in relatively small binding energies and widths of the calculated $\eta$ nuclear bound states. We argue that the subthreshold behavior of $\eta N$ scattering amplitudes is crucial to conclude whether $\eta$ nuclear states exist, in which nuclei the $\eta$ meson could be bound and if the corresponding widths are small enough to allow detection of these $\eta$ nuclear states in experiment., Comment: 7 pages, 5 figures; presented at HADRON2017, Sept. 25-29, 2017, Salamanca (Spain); prepared for Proceedings of Science

We report on our recent self-consistent calculations of $K^-$ nuclear quasi-bound states using $K^-$ optical potentials derived from chirally motivated meson-baryon coupled channels models [1,2]. The $K^-$ single-nucleon potentials were supplemented by a phenomenological $K^-$ multi-nucleon interaction term introduced to achieve good fits to $K^-$ atom data. We demonstrate a substantial impact of the $K^-$ multi-nucleon absorption on the widths of $K^-$ nuclear states. If such states ever exist in nuclear many-body systems, their widths are excessively large to allow observation., Comment: 9 pages, 5 figures, proceedings of the EXA2017 conference, Vienna, Austria, September 11 - 15, 2017

$K^-$ optical potentials relevant to calculations of $K^-$ nuclear quasi-bound states were developed within several chiral meson-baryon coupled-channel interaction models. The applied models yield quite different $K^-$ binding energies and widths. Then, the $K^-$ multinucleon interactions were incorporated by a phenomenological optical potential fitted recently to kaonic atom data. Though the applied $K^-$ interaction models differ significantly in the $K^-N$ subthreshold region, our self-consistent calculations of kaonic nuclei across the periodic table lead to conclusions valid quite generally. Due to $K^-$ multinucleon absorption in the nuclear medium the calculated widths of $K^-$ nuclear states are sizable, $\Gamma_{K^-} \geq 90$ MeV, and exceed substantially their binding energies in all considered nuclei., Comment: 25 pages, 24 figures

We present our latest calculations of $K^-$-nuclear quasi-bound states using a self-consistent scheme for constructing $K^-$-nuclear potentials from various subthreshold chirally inspired $\bar{K}N$ scattering amplitudes. We consider in-medium versions of the scattering amplitudes taking into account Pauli blocking in the intermediate states. The resulting $K^-$ binding energies as well as the widths exhibit the same A dependence, however, the binding energies strongly depend on the model used., Comment: 4 pages, proceedings of the MESON 2016 conference, Krakow, Poland, June 2 - 7, 2016

We introduce a mean field model based on realistic 2-body baryon interactions and calculate spectra of a set of p-shell and sd-shell {\Lambda} hypernuclei - 13{\Lambda}C, 17{\Lambda}O, 21{\Lambda}Ne, 29{\Lambda}Si and 41{\Lambda}Ca. The hypernuclear spectra are compared with the results of a relativistic mean field (RMF) model and available experimental data. The sensitivity of {\Lambda} single-particle energies to the nuclear core structure is explored. Special attention is paid to the effect of spin-orbit {\Lambda}N interaction on the energy splitting of the {\Lambda} single particle levels 0p3/2 and 0p1/2. In particular, we analyze the contribution of the symmetric (SLS) and the anti-symmetric (ALS) spin-orbit terms to the energy splitting. We give qualitative predictions for the calculated hypernuclei.

A not satisfactorily solved problem of relativistic transformation of temperature playing the decisive role in relativistic thermal physics and cosmology is reopened. It is shown that the origin of the so called Mosengeil-Ott's antinomy and other aligned paradoxes are related to the wrong understanding of physical meaning of temperature and application of Planck's Ansatz of Lorentz's invariance of entropy. In the contribution we have thus reintroduced and anew analyzed fundamental concepts of hotness manifold, fixed thermometric points and temperature. Finally, on the basis of phenomenological arguments the Lorentz invariance of temperature and relativistic transformations of entropy are established., Comment: 9 pages

In this paper, we discuss some of the consequences of the CGPM (1983) definition of meter and, in particular, we discuss giving the speed of light an exact value. It is shown that this act touches the fundamental paradigms, such as the second postulate of the special theory of relativity (STR), the c-equivalence principle and the method of time synchronization. In order to fill the arising logical gaps, we suggest, among others, to weaken the second postulate of STR to a form directly confirmed by experiments and make new measurements of Maxwell's constant with accuracy comparable with that of the speed of light., Comment: 17 pages, 1 figure

We performed fully self-consistent calculations of $\bar{p}$-nuclear bound states using a complex ${\bar p}$-nucleus potential accounting for $\bar{p}$-atom data. While the real part of the potential is constructed within the relativistic mean-field (RMF) model, the $\bar{p}$ annihilation in the nuclear medium is described by a phenomenological optical potential. We confirm large polarization effects of the nuclear core caused by the presence of the antiproton. The ${\bar p}$ annihilation is treated dynamically, taking into account explicitly the reduced phase space for annihilation from deeply bound states as well as the compressed nuclear density due to the antiproton. The energy available for the products of ${\bar p}$ annihilation in the nuclear medium is evaluated self-consistently, considering the additional energy shift due to transformation from the ${\bar p}N$ system to ${\bar p}$-nucleus system. Corresponding $\bar{p}$ widths in the medium are significantly suppressed, however, they still remain considerable for the $\bar{p}$ potential consistent with experimental data., Comment: preprint submitted to Nuclear Physics A

We calculated antibaryon ($\bar{B}$ = $\bar{p}$, $\bar{\Lambda}$, $\bar{\Sigma}$, $\bar{\Xi}$) bound states in selected nuclei within the relativistic mean-field (RMF) model. The G-parity motivated $\bar{B}$-meson coupling constants were scaled to yield corresponding potentials consistent with available experimental data. Large polarization of the nuclear core caused by $\bar{B}$ was confirmed. The $\bar{p}$ annihilation in the nuclear medium was incorporated by including a phenomenological imaginary part of the optical potential. The calculations using a complex $\bar{p}$-nucleus potential were performed fully self-consistently. The $\bar{p}$ widths significantly decrease when the phase space reduction is considered for $\bar{p}$ annihilation products, but they still remain sizeable for potentials consistent with $\bar{p}$-atom data., Comment: 5 pages, 3 figures, 1 table, talk given at the workshop for young scientists with research interests focused on physics at FAIR - FAIRNESS2014, September 22-27, 2014, Vietri sul Mare, Italy

The in-medium Eta-N interaction near and below threshold is constructed from a free-space chirally-inspired meson-baryon coupled-channel model that captures the physics of the N(1535) baryon resonance. Nucleon Pauli blocking and hadron self-energies are accounted for. The resulting energy dependent in-medium interaction is used in self-consistent dynamical calculations of Eta nuclear bound states. Narrow states of width about or less than 2 MeV are found across the periodic table, beginning with A=10, for this in-medium coupled-channel interaction model. The binding energy of the 1s-Eta state increases with A, reaching a value of B(1s-Eta) about 15 MeV. The implications of our self-consistency procedure are discussed with respect to procedures used in other works., Comment: 21 pages, 1 table, 8 figures, matches published NPA version plus a new review [34] cited

We report on a novel ab initio approach for nuclear few- and many-body systems with strangeness. Recently, we developed a relevant no-core shell model technique which we successfully applied in first calculations of lightest $\Lambda$ hypernuclei. The use of a translationally invariant finite harmonic oscillator basis allows us to employ large model spaces, compared to traditional shell model calculations, and use realistic nucleon-nucleon and nucleon-hyperon interactions (such as those derived from EFT). We discuss formal aspects of the methodology, show first demonstrative results for ${}_{\Lambda}^3$H, ${}_{\Lambda}^4$H and ${}^4_\Lambda$He, and give outlook., Comment: 4 pages, 3 figures; Proceedings of the 22nd European Conference on Few Body Problems in Physics, 9 - 13 September, 2013, Cracow, Poland

The strong energy dependence of the s-wave eta-N scattering amplitude at and below threshold, as evident in coupled-channels K-matrix fits and chiral models that incorporate the S11 N*(1535) resonance, is included self-consistently in eta-nuclear bound-state calculations. This approach, applied recently in calculations of kaonic atoms and Kbar-nuclear bound states, is found to impose stronger constraints than ever on the onset of eta-nuclear binding, with a minimum value of Re a_{eta N} approximately 0.9 fm required to accommodate an eta-4He bound state. Binding energies and widths of eta-nuclear states are calculated within several underlying eta-N models for nuclei across the periodic table, including eta-25Mg for which some evidence was proposed in a recent COSY experiment., Comment: v3: 13 pages, including 3 figures and 2 tables, matching published PLB version

In-medium ${\bar K}N$ scattering amplitudes developed within a new chirally motivated coupled-channel model due to Cieply and Smejkal that fits the recent SIDDHARTA kaonic hydrogen 1s level shift and width are used to construct $K^-$ nuclear potentials for calculations of $K^-$ nuclear quasi-bound states. The strong energy and density dependence of scattering amplitudes at and near threshold leads to $K^-$ potential depths $-Re V_K \approx 80 -120$ MeV. Self-consistent calculations of all $K^-$ nuclear quasi-bound states, including excited states, are reported. Model dependence, polarization effects, the role of p-wave interactions, and two-nucleon $K^-NN\rightarrow YN$ absorption modes are discussed. The $K^-$ absorption widths $\Gamma_K$ are comparable or even larger than the corresponding binding energies $B_K$ for all $K^-$ nuclear quasi-bound states, exceeding considerably the level spacing. This discourages search for $K^-$ nuclear quasi-bound states in any but lightest nuclear systems., Comment: 12 pages, 11 figures

The ALICE Collaboration has measured inclusive J/psi production in pp collisions at a center of mass energy sqrt(s)=2.76 TeV at the LHC. The results presented in this Letter refer to the rapidity ranges |y|<0.9 and 2.5

A self consistent scheme for constructing K^- nuclear optical potentials from subthreshold in-medium Kbar-N s-wave scattering amplitudes is presented and applied to analysis of kaonic atoms data and to calculations of K^- quasibound nuclear states. The amplitudes are taken from a chirally motivated meson-baryon coupled-channel model, both at the Tomozawa-Weinberg leading order and at the next to leading order. Typical kaonic atoms potentials are characterized by a real part -Re V(K^-;chiral)=(85+/-5) MeV at nuclear matter density, in contrast to half this depth obtained in some derivations based on in-medium Kbar-N threshold amplitudes. The moderate agreement with data is much improved by adding complex rho- and rho^2-dependent phenomenological terms, found to be dominated by rho^2 contributions that could represent Kbar-NN -> YN absorption and dispersion, outside the scope of meson-baryon chiral models. Depths of the real potentials are then near 180 MeV. The effects of p-wave interactions are studied and found secondary to those of the dominant s-wave contributions. The in-medium dynamics of the coupled-channel model is discussed and systematic studies of K^- quasibound nuclear states are presented., Comment: extension of Phys. Lett. B 702, 402 (2011) by the same authors; v2: minor corrections, matching PRC version

In-medium subthreshold KbarN scattering amplitudes calculated within a chirally motivated meson-baryon coupled-channel model are used self consistently to confront K^- atom data across the periodic table. Substantially deeper K^- nuclear potentials are obtained compared to the shallow potentials derived in some approaches from threshold amplitudes, with Re V_{chiral} = -(85+/-5) MeV at nuclear matter density. When KbarNN contributions are incorporated phenomenologically, a very deep K^- nuclear potential results, Re V_{chiral+phen.} = -(180+/-5) MeV, in agreement with density dependent potentials obtained in purely phenomenological fits to the data. Self consistent dynamical calculations of K^- nuclear quasibound states are reported and discussed., Comment: extended discussion, unchanged results and conclusions, accepted by PLB

Relativistic mean field calculations of multi-$\bar{K}$ hypernuclei are performed by adding $K^-$ mesons to particle-stable configurations of nucleons, $\Lambda$ and $\Xi$ hyperons. For a given hypernuclear core, the calculated $\bar{K}$ separation energy $B_{\bar{K}}$ saturates with the number of $\bar{K}$ mesons for more than roughly 10 mesons, with $B_{\bar{K}}$ bounded from above by 200 MeV. The associated baryonic densities saturate at values 2-3 times nuclear-matter density within a small region where the $\bar{K}$-meson densities peak, similarly to what was found for multi-$\bar{K}$ nuclei. The calculations demonstrate that particle-stable multistrange $\{N,\Lambda,\Xi \}$ configurations are stable against strong-interaction conversions $\Lambda \to N \bar{K}$ and $\Xi \to N \bar{K} \bar{K}$, confirming and strengthening the conclusion that kaon condensation is unlikely to occur in strong-interaction self-bound strange hadronic matter., Comment: 21 pages, 7 figures, revised figures and text

The effect of the magnetic field on a capacitor with a superconducting electrode is studied within the Ginzburg-Landau approach. It is shown that the capacitance has a discontinuity at the onset of the surface superconductivity $B_{\rm c3}$ which is expressed as a discontinuity in the penetration depth of the electric field into metals. Estimates show that this discontinuity is observable with recent bridges for both conventional and high-$T_{\rm c}$ superconductors of the type-II.

We extend previous relativistic mean-field (RMF) calculations of multi-$\bar K$ nuclei, using vector boson fields with SU(3) PPV coupling constants and scalar boson fields constrained phenomenologically. For a given core nucleus, the resulting $\bar K$ separation energy $B_{\bar K}$, as well as the associated nuclear and $\bar K$-meson densities, saturate with the number $\kappa$ of $\bar K$ mesons for $\kappa > \kappa_{\rm sat} \sim 10$. Saturation appears robust against a wide range of variations, including the RMF nuclear model used and the type of boson fields mediating the strong interactions. Because $B_{\bar K}$ generally does not exceed 200 MeV, it is argued that multi-$\bar K$ nuclei do not compete with multihyperonic nuclei in providing the ground state of strange hadronic configurations and that kaon condensation is unlikely to occur in strong-interaction self-bound strange hadronic matter. Last, we explore possibly self-bound strange systems made of neutrons and ${\bar K}^0$ mesons, or protons and $K^-$ mesons, and study their properties., Comment: 21 pages, 8 figures, revised text and references

We report on self-consistent calculations of single-K^- nuclear states and multi-Kbar nuclear states in 12C, 16O, 40Ca and 208Pb within the relativistic mean-field (RMF) approach. Gradient terms motivated by the p-wave resonance Sigma(1385) are found to play a secondary role for single-K^- nuclear systems where the mean-field concept is acceptable. Significant contributions from the Kbar N -> pi Lambda conversion mode, and from the nonmesonic Kbar NN -> YN conversion modes which are assumed to follow a rho^2 density dependence, are evaluated for the deep binding-energy range of over 100 MeV where the decay channel Kbar N -> pi Sigma is closed. Altogether we obtain K^- total decay widths of 50-100 MeV for binding energies exceeding 100 MeV in single-K^- nuclei. Multi-Kbar nuclear calculations indicate that the binding energy per Kbar meson saturates upon increasing the number of Kbar mesons embedded in the nuclear medium. The nuclear and Kbar densities increase only moderately and are close to saturation, with no indication of any kaon-condensation precursor., Comment: 31 pages, 11 figures, revised Figures 8 and 10, and Table II, and related text

Coupled-channel three-body calculations of an $I=1/2$, $J^{\pi}=0^-$ $\bar{K}NN$ quasi-bound state in the $\bar{K}NN - \pi \Sigma N$ system were performed and the dependence of the resulting three-body energy on the two-body $\bar{K}N - \pi \Sigma$ interaction was investigated. Earlier results of binding energy $B_{K^-pp} \sim 50 -70$ MeV and width $\Gamma_{K^-pp} \sim 100$ MeV are confirmed [N.V. Shevchenko {\it et al.}, Phys. Rev. Lett. {\bf 98}, 082301 (2007)]. It is shown that a suitably constructed energy-independent complex $\bar{K}N$ potential gives a considerably shallower and narrower three-body quasi-bound state than the full coupled-channel calculation. Comparison with other calculations is made., Comment: 22 pages, 7 figures, 4 tables; minor corrections, accepted for publication in Phys. Rev. C

We report on the first genuinely three-body ${\bar K}NN - \pi \Sigma N$ coupled-channel Faddeev calculation in search for quasi-bound states in the $K^- p p$ system. The main absorptivity in the $K^- p$ subsystem is accounted for by fitting to $K^- p$ data near threshold. Our calculation yields one such quasi-bound state, with $I=1/2$, $J^{\pi}=0^-$, bound in the range $B \sim 55-70$ MeV, with a width of $\Gamma \sim 95-110$ MeV. These results differ substantially from previous estimates, and are at odds with the $K^- p p \to \Lambda p$ signal observed by the FINUDA collaboration., Comment: Minor editorial revision; version accepted for publication in Phys. Rev. Lett

A comprehensive data base of K- atom level shifts and widths is re-analyzed in order to study the density dependence of the Kbar-nuclear optical potential. Significant departure from a t*rho form is found only for nuclear densities about and less than 20% of nuclear-matter density, and extrapolation to nuclear-matter density yields an attractive potential, about 170 MeV deep. Partial restoration of chiral symmetry compatible with pionic atoms and low-energy pion-nuclear data plays no role at the relevant low-density regime, but this effect is not ruled out at high densities. Kbar-nuclear bound states are generated across the periodic table self consistently, using a relativistic mean-field model Lagrangian which couples the Kbar to the scalar and vector meson fields mediating the nuclear interactions. The reduced phase space available for Kbar absorption from these bound states is taken into account by adding an energy-dependent imaginary term which underlies the corresponding Kbar-nuclear level widths, with a strength required by fits to the atomic data. Substantial polarization of the core nucleus is found for light nuclei, and the binding energies and widths calculated in this dynamical model differ appreciably from those calculated for a static nucleus. A wide range of binding energies is spanned by varying the Kbar couplings to the meson fields. Our calculations provide a lower limit of Gamma(Kbar) = 50 +/- 10 MeV on the width of nuclear bound states for Kbar binding energy in the range B(Kbar) = 100 - 200 MeV. Comments are made on the interpretation of the FINUDA experiment at DAFNE, Frascati, which claimed evidence for deeply bound (K- pp) states in light nuclei., Comment: Added 2 figures and discussion. Version accepted for publication in NPA

We report on global fits of optical-model parameters to 90 data points for $\bar p$ X-rays and 17 data points of radiochemical data put together. With the help of separate fits to the two kinds of data it is possible to determine phenomenologically the radial region where the absorption of antiprotons takes place and to obtain neutron densities which represent the average behaviour over the periodic table. A finite-range attractive and absorptive $\bar p$-nuclear isoscalar potential fits the data well. Self-consistent dynamical calculations within the RMF model demonstrate that the polarization of the nucleus by the {\it atomic} antiproton is negligible., Comment: 18 pages, 6 figures, one table. Extended discussion, to appear in Nucl. Phys. A

We apply, for the first time, an energy dependent Schrodinger equation to describe static properties of heavy quark systems, i.e. charmonium and bottonium. We show that a good description of the eigenstates and reasonable values for the widths can be obtained. Values of the radii and of the density at the origin are also given. We compare the results to those deduced with a Schrodinger equation implemented with potentials used so far. We note that the energy dependence of the confining potential provides a natural mechanism for the saturation of the spectra. Our results introduce a new class of potentials for the description of heavy quark systems., Comment: 3 pages

The relativistic mean field (RMF) model is applied to a system of nucleons and a $\bar K$ meson, interacting via scalar and vector boson fields. The model incorporates the standard RMF phenomenology for bound nucleons and, for the $\bar K$ meson, it relates to low-energy ${\bar K}N$ and $K^-$ atom phenomenology. Deeply bound $\bar K$ nuclear states are generated dynamically across the periodic table and are exhibited for $^{12}$C and $^{16}$O over a wide range of binding energies. Substantial polarization of the core nucleus is found for these light nuclei. Absorption modes are also included dynamically, considering explicitly the reduced phase space for $\bar K$ absorption from deeply bound states. The behavior of the calculated width as function of the $\bar K$ binding energy is studied in order to explore limits on the possible existence of narrow $\bar K$ nuclear states., Comment: 12 pages, 1 table, 3 figures Minor changes, to appear in PLB

The Budd-Vannimenus theorem is modified to apply to superconductors in the Meissner state. The obtained identity links the surface value of the electrostatic potential to the density of free energy at the surface which allows one to evaluate the electrostatic potential observed via the capacitive pickup without the explicit solution of the charge profile., Comment: 7 pages, 1 figure

The electrostatic potential close to the surface of superconductors in the Meissner state is discussed. We show that beside the Bernoulli potential, the quasiparticle screening, and the thermodynamic contribution due to Rickayzen, there is a non-local contribution which is large for both type-I and weak type-II superconductors., Comment: 7 pages, 4 figures

We study wave equations with energy dependent potentials. Simple analytical models are found useful to illustrate difficulties encountered with the calculation and interpretation of observables. A formal analysis shows under which conditions such equations can be handled as evolution equation of quantum theory with an energy dependent potential. Once these conditions are met, such theory can be transformed into ordinary quantum theory., Comment: 33 pages, 5 tables, 1 figure

The $K^-$ optical potential in the nuclear medium is evaluated self consistently from a free-space $K^-N$ $t$ matrix constructed within a coupled-channel chiral approach to the low-energy $\bar K N$ data. The chiral-model parameters are fitted to a select subset of the low-energy data {\it plus} the $K^-$ atomic data throughout the periodic table. The resulting attractive $K^-$ optical potentials are relatively `shallow', with central depth of the real part about 55 MeV, for a fairly reasonable reproduction of the atomic data with $\chi^2 / N \approx 2.2$. Relatively `deep' attractive potentials of depth about 180 MeV, which result in other phenomenological approaches with $\chi^2 / N \approx 1.5$, are ruled out within chirally motivated models. Different physical data input is required to distinguish between shallow and deep $K^-$ optical potentials. The ($K^{-}_{\rm stop},\pi$) reaction could provide such a test, with exclusive rates differing by over a factor of three for the two classes of potentials. Finally, forward ($K^-,p$) differential cross sections for the production of relatively narrow deeply bound $K^-$ {\it nuclear} states are evaluated for deep $K^-$ optical potentials, yielding values considerably lower than those estimated before., Comment: 22 pages, 3 figures, minor revisions, Nucl. Phys. A in press

$K^-$ atomic data are used to test several models of the $K^-$ nucleus interaction. The t($\rho$)$\rho$ optical potential, due to coupled channel models incorporating the $\Lambda$(1405) dynamics, fails to reproduce these data. A standard relativistic mean field (RMF) potential, disregarding the $\Lambda$(1405) dynamics at low densities, also fails. The only successful model is a hybrid of a theoretically motivated RMF approach in the nuclear interior and a completely phenomenological density dependent potential, which respects the low density theorem in the nuclear surface region. This best-fit $K^-$ optical potential is found to be strongly attractive, with a depth of 180 \pm 20 MeV at the nuclear interior, in agreement with previous phenomenological analyses., Comment: revised, Phys. Rev. C in press

We calculate the binding energy of two $\Lambda$ hyperons bound to a nuclear core within the relativistic mean field theory. The starting point is a two-body relativistic equation of the Breit type suggested by the RMFT, and corrected for the two-particle interaction. We evaluate the 2 $\Lambda$ correlation energy and estimate the contribution of the $\sigma^*$ and $\Phi$ mesons, acting solely between hyperons, to the bond energy $\Delta{B_{\Lambda\Lambda}}$ of $^6_{\Lambda\Lambda}He$, $^{10}_{\Lambda\Lambda}Be$ and $^{13}_{\Lambda\Lambda}B$. Predictions of the $\Delta{B_{\Lambda\Lambda}}$ A dependence are made for heavier $\Lambda$-hypernuclei., Comment: 15 pages, RevTeX, 2 Postscript figures, submitted Phys. Rev. C

Total and reaction cross sections are derived self consistently from the attenuation cross sections measured in transmission experiments at the AGS for K^+ on Li^6, C, Si and Ca in the momentum range of 500-700 MeV/c by using a V_{opt}=t_{eff}(rho)rho optical potential. Self consistency requires, for the KN in-medium t matrix, that Im t_{eff}(rho) increases linearly with the average nuclear density in excess of a threshold value of 0.088+-0.004 fm^-3. The density dependence of Re t_{eff}(rho) is studied phenomenologically, and also applying a relativistic mean field approach, by fitting the integral cross sections. The real part of the optical potential is found to be systematically less repulsive with increasing energy than expected from the free-space repulsive KN interaction. When the elastic scattering data for Li^6 and C at 715 MeV/c are included in the analysis, a tendency of Re V_{opt} to generate an attractive pocket at the nuclear surface is observed., Comment: 23 pages, RevTeX, 2 postscript figures, submitted Nucl. Phys. A

Self consistency in the analysis of transmission measurements for K^+ on several nuclei in the momentum range of 500-700 MeV/c is achieved with a "t_{eff}(rho)rho" potential and new results are derived for total cross sections. The imaginary part of the t_{eff} amplitude is found to increase linearly with the average nuclear density in excess of a threshold value. This phenomenological density dependence of the K^+ nucleus optical potential also gives rise to good agreement with recent measurements of differential cross sections for elastic scattering of 715 MeV/c K^+ by Li^6 and C., Comment: 11 pages, RevTeX, 2 Postscript figures, submitted Phys. Lett. B

Strong interaction level shifts and widths in $\Sigma^-$ atoms are analyzed by using a $\Sigma$ nucleus optical potential constructed within the relativistic mean field approach. The analysis leads to potentials with a repulsive real part in the nuclear interior. The data are sufficient to establish the size of the isovector meson--hyperon coupling. Implications to $\Sigma$ hypernuclei are discussed., Comment: 18 pages, RevTex, 4 uuencoded figures, subm. Nucl.Phys.A