Search

We study to what extent the unique observation of $\Lambda\Lambda$ hypernuclei by their weak decay into known $\Lambda$ hypernuclei, with lifetimes of order 10$^{-10}$ s, rules out the existence of a deeply bound doubly-strange (${\cal S}$=$-$2) $H$ dibaryon. Treating ${_{\Lambda\Lambda}^{~~6}}{\rm He}$ (the Nagara emulsion event) in a realistic $\Lambda-\Lambda-{^4}$He three-body model, we find that the ${_{\Lambda\Lambda}^{~~6}}{\rm He}\to H + {^4{\rm He}}$ strong-interaction lifetime increases beyond 10$^{-10}$ s for $m_H < m_{\Lambda}+m_n$, about 176 MeV below the $\Lambda\Lambda$ threshold, so that such a deeply bound $H$ is not in conflict with hypernuclear data. Constrained by $\Lambda$ hypernuclear $\Delta{\cal S}$=1 nonmesonic weak-interaction decay rates, we follow EFT methods to evaluate the $\Delta{\cal S}$=2 $H\to nn$ weak-decay lifetime of $H$ in the mass range $2m_n \lesssim m_H < m_{\Lambda}+m_n$. The resulting $H$ lifetime is of order 10$^5$ s, many orders of magnitude shorter than required to qualify for a dark-matter candidate., Comment: v1: 17 pages, 2 figures, 3 tables; v2: slightly edited, Table 3 corrected, submitted for publication; v3: slightly edited in response to referee's comments, 19 pages, 2 figures, 3 tables, PLB published version

We recently showed that all five KEK and J-PARC uniquely assigned two-body $\Xi^-$+${^A}$Z$\to{_{\Lambda}^{A'}}$Z'+${_{\Lambda}^{A''}}$Z'' capture events in CNO light emulsion nuclei are consistent with Coulomb-assisted $1p_{\Xi^-}$ nuclear states in a $\Xi$-nuclear potential of nuclear-matter depth $V_{\Xi}\gtrsim 20$ MeV [1]. Here we argue that the recently reported $^{14}$N capture events named KINKA and IRRAWADDY are more likely $1p_{\Xi^0}$--$^{14}$C nuclear states [2] than $1s_{\Xi^-}$--$^{14}$N states, the latter assignment implying considerably smaller values of $V_{\Xi}$., Comment: 6 pages, 3 figures, 2 tables; invited talk at MESON2023, Krakow, June 2023, plus updated discussion section; v1: as submitted to EPJ Web of Conferences; v2: updated, published version

A minimally constructed $\Lambda$-nucleus density-dependent optical potential is used to calculate binding energies of observed $1s_{\Lambda}$, $1p_{\Lambda}$ states across the periodic table, leading to a repulsive $\Lambda NN$ contribution $D_{\Lambda}^{(3)}\approx 14$ MeV to the phenomenological $\Lambda$-nucleus potential depth $D_{\Lambda}\approx -30$ MeV. This value is significant in connection with the so-called 'hyperon puzzle'., Comment: Invited talk at HYP2022, Prague, June-July 2022, reporting on a recent Phys. Lett. B published work [arXiv:2204.02264]. arXiv admin note: substantial text overlap with arXiv:2204.02264

All five KEK and J-PARC two-body $\Xi^-$+$^A$Z $\to$ $^{A'}_{\Lambda}$Z'+$^{A''}_{\Lambda}$Z'' capture events in light emulsion nuclei, including KISO and IBUKI in $^{14}$N, are consistent with Coulomb-assisted $1p_{\Xi^-}$ nuclear states. The underlying $\Xi$-nuclear potential is strongly attractive, with nuclear-matter depth $V_{\Xi}$ larger than 20 MeV. The recent $^{14}$N capture events KINKA and IRRAWADDY assigned by J-PARC E07 to $1s_{\Xi^-}$ nuclear states, and implying considerably shallower $V_{\Xi}$, have also another interpretation as $1p_{\Xi^0}$ nuclear states., Comment: Invited talk at HYP2022, Prague, June-July 2022, reporting on recent Phys. Lett. B published work [15,24]. Published in EPJ Web of Conferences 271, 03002 (2022)

Few-body $\Lambda$ hypernuclei provide valuable information towards understanding strange matter. Recent experimental progress by the STAR Collaboration at the RHIC facility and by the ALICE Collaboration at the LHC has been matched by theoretical progress reviewed here: (i) lifetimes of the hypertriton $_{\Lambda}^3$H, $_{\Lambda}^3$n if particle-stable, $_{\Lambda}^4$H and $_{\Lambda}^4$He and their charge symmetry breaking, and (ii) the onset of $\Lambda\Lambda$ hypernuclear binding., Comment: Invited talk at the 19th International Conference on Strangeness in Quark Matter (SQM 2021), online from BNL Upton NY USA, May 2021. Submitted to EPJ Web of Conferences. v2: Ref.[30] added, errors corrected. v3: updated slightly beyond published version

We discuss a recent extraction of the $\pi N$ $\sigma$ term $\sigma_{\pi N}$ from a large-scale fit of pionic-atom strong-interaction data across the periodic table. The value thus derived, $\sigma_{\pi N}^{\rm FG}=57\pm 7$ MeV, is directly connected via the Gell-Mann--Oakes--Renner expression to the medium-renormalized $\pi N$ isovector scattering amplitude near threshold. It compares well with the value derived recently by the Bern-Bonn-J\"{u}lich group, $\sigma_{\pi N}^{\rm RS}=58\pm 5$ MeV, using the Roy-Steiner equations to control the extrapolation of the vanishingly small near threshold $\pi N$ isoscalar scattering amplitude to zero pion mass., Comment: 10 pages, 3 figures; presented at the 15th International Conference on Meson-Nucleon (MENU) Physics and the Structure of the Nucleon, Pittsburgh, and in a slightly different form at the 3rd Jagiellonian Symposium on Fundamental and Applied Subatomic Physics, Krak\'ow, both in June 2019; v2: typos corrected

We review the current status of our study of $K^-$-nuclear interactions and $K^-$-nuclear quasi-bound states. The adopted $K^-$-nuclear optical potential consists of two parts -- the single-nucleon one constructed microscopically from chirally motivated $\bar{K}N$ amplitudes, and a phenomenological multi-nucleon one constrained in fits to kaonic atoms data. The inclusion of multi-nucleon absorption in our calculations of $K^{-}$ quasi-bound states in many-body systems leads to huge widths, considerably exceeding the binding energies. If this feature is confirmed the observation of such states is unlikely. Finally, a development of a new microscopical model for in-medium $K^-NN$ absorption is discussed as well., Comment: 7 pages, 9 figures, to appear in MENU2019 conference proceedings

The status of $N\Delta$ and $\Delta\Delta$ dibaryons introduced by Dyson and Xuong in 1964 is briefly reviewed with focus on the d*(2380), tentatively assigned as a $\Delta\Delta$ dibaryon resonance. It is argued that the apparently small value of width, $\Gamma_{d^\ast}$$\approx$70 MeV, favors hadronic structure for the d*(2380) dibaryon rather than a six-quark structure., Comment: updated version of talks given at MESON 2018, Krak\'{o}w [1], and at QNP 2018, Tsukuba [2]. arXiv admin note: substantial text overlap with arXiv:1803.08788

Some of last year's progress made in hypernuclear physics is reviewed as follows: (i) resolving the $_{\Lambda}^5$He overbinding problem in single-$\Lambda$ hypernuclei [1]; (ii) arguing that the onset of binding double-$\Lambda$ hypernuclei is most likely at $A$=5, with the neutral systems $_{\Lambda\Lambda}^{\,\,3}$n and $_{\Lambda\Lambda}^{\,\,4}$n unbound by a large margin [2]; and (iii) revising the calculated value of the loosely bound $_{\Lambda}^3$H lifetime to a level of $\sim$20% shorter than the free $\Lambda$ lifetime [3], given recent claims from relativistic heavy ion experiments that $\tau(_{\Lambda}^3$H) is shorter than $\tau_{\Lambda}$ by as much as $\approx$(30$\pm$8)%. Also discussed briefly in this context is the lifetime expected for the questionable $_{\Lambda}^3$n hypernucleus., Comment: 8 pages, invited talk at the 27th INPC, Glasgow UK, July 2019, prepared for Journal of Physics Conference Series

We present an effective field theory (EFT) at leading order to describe light single-$\Lambda$ hypernuclei. Owing to the weak $\Lambda$ binding and to the $\Lambda N$ short interaction range, meson exchange forces are approximated by contact interactions within a pionless EFT where the only degrees of freedom are baryons. At leading order, the $\Lambda$-nuclear interaction contains two 2-body (singlet and triplet) and three 3-body interaction terms, a total of 5 terms associated with 5 coupling strengths or low energy constants (LECs). We adopt the 2-body LECs from hyperon-nucleon scattering data and interaction models that constrain the $\Lambda N$ scattering lengths, while the 3-body LECs are adjusted using both 3-body and 4-body hypernuclear binding energies. To calculate the binding energies for A-body systems with A$>$2, we expand the wavefunctions using a correlated Gaussian basis. The stochastic variational method is employed to select the non-linear parameters. The resulting \nopieft~is then applied to calculate the $\Lambda$ separation energy in $_\Lambda^5$He, where the adjusted 3-body interactions largely resolve the known overbinding problem of $_\Lambda^5$He., Comment: HYP2018 conference proceeding

Diquark models have been applied with varying degree of success to tetraquark and pentaquark states involving both light and heavy quark degrees of freedom. We discuss the applicability of such models to light quark dibaryons, viewed as three-diquark objects. Highlighting the case of the d*(2380) dibaryon resonance, we demonstrate the inapplicability of diquark models in the light quark sector., Comment: v2 -- inessential minor changes with respect to v1, matches published EPJC version

Recent $_\Lambda^3$H lifetime measurements in relativistic heavy ion collision experiments have yielded values shorter by (30$\pm$8)% than the free $\Lambda$ lifetime $\tau_\Lambda$, thereby questioning the naive expectation that $\tau({_\Lambda^3}{\rm H})\approx\tau_\Lambda$ for a weakly bound $\Lambda$ hyperon. Here we apply the closure approximation introduced by Dalitz and coworkers to evaluate the $_\Lambda^3$H lifetime, using $_\Lambda^3$H wavefunctions generated by solving three-body Faddeev equations. Our result, disregarding pion final-state interaction (FSI), is $\tau({_\Lambda^3}{\rm H})$=(0.90$\pm$0.01)$\tau_\Lambda$. In contrast to previous works, pion FSI is found attractive, reducing further $\tau({_\Lambda^3}{\rm H})$ to $\tau({_\Lambda^3}{\rm H})$=(0.81$\pm$0.02)$\tau_\Lambda$. We also evaluate for the first time $\tau({_\Lambda^3}{\rm n})$, finding it considerably longer than $\tau_\Lambda$, contrary to the shorter lifetime values suggested by the GSI HypHI experiment for this controversial hypernucleus., Comment: v2--14 pages, 1 figure, 2 tables, replaced title of v1 and recalculated a shorter $_\Lambda^3$H lifetime than reported in v1; v3--updated references, matching published version

Several persistent problems in strangeness nuclear physics are discussed in this opening talk at HYP2018, Portsmouth-Norfolk VA, June 2018: (i) the $^3_{\Lambda}$H and $^3_{\Lambda}$n (if existing) lifetimes; (ii) charge symmetry breaking in $\Lambda$ hypernuclei; (iii) the overbinding of $^5_{\Lambda}$He which might be related to the hyperon puzzle in neutron stars; and (iv) does $\Lambda^\ast$(1405) survive in strange hadronic matter?, Comment: 12 pages, 7 figures, 3 tables; v2--updated $^3_{\Lambda}$H lifetime calculation results [48] in Table 3; v3--updated references, matching published version

A recent suggestion [PLB 774 (2017) 522] that purely-$\Lambda^{\ast}(1405)$ nuclei provide the absolute minimum energy in charge-neutral baryon matter for baryon-number $A\gtrsim 8$, is tested within RMF calculations. A broad range of $\Lambda^{\ast}$ interaction strengths, commensurate with $(\bar K \bar K NN)_{I=0}$ binding energy assumed to be of order 100 MeV, is scanned. It is found that the binding energy per $\Lambda^{\ast}$, $B/A$, saturates for $A\gtrsim 120$ with values of $B/A$ considerably below 100 MeV, implying that $\Lambda^{\ast}(1405)$ matter is highly unstable against strong decay to $\Lambda$ and $\Sigma$ hyperon aggregates. The central density of $\Lambda^{\ast}$ matter is found to saturate as well, at roughly twice nuclear matter density. Moreover, it is shown that the underlying very strong $\bar K N$ potentials, fitted for isospin $I=0$ to the mass and width values of $\Lambda^{\ast}(1405)$, fail to reproduce values of single-nucleon absorption fractions deduced across the periodic table from $K^-$ capture-at-rest bubble chamber experiments., Comment: v2 -- slightly added discussion, version accepted for publication in Phys. Lett. B

We address the $\Lambda$-hypernuclear `overbinding problem' in light hypernuclei which stands for a 1--3 MeV excessive $\Lambda$ separation energy calculated in $_{\Lambda}^5$He. This problem arises in most few-body calculations that reproduce ground-state $\Lambda$ separation energies in the lighter $\Lambda$ hypernuclei within various hyperon-nucleon interaction models. Recent pionless effective field theory nuclear few-body calculations are extended in this work to $\Lambda$ hypernuclei. At leading order, the $\Lambda N$ low-energy constants are associated with $\Lambda N$ scattering lengths and the $\Lambda NN$ low-energy constants are fitted to $\Lambda$ separation energies ($B_{\Lambda}^{\rm exp}$) for $A\leq 4$. The resulting pionless-EFT interaction reproduces in few-body stochastic variational method calculations the reported value $B_{\Lambda}^{\rm exp}(_{\Lambda}^5 $He)=3.12$\pm$0.02 MeV within a fraction of MeV over a broad range of momentum-space cut-off parameters. Possible consequences and extensions to heavier hypernuclei and to neutron-star matter are discussed., Comment: matches published PRL 121 (2018) 102502 with one minor correction: the number of nuclear plus hypernuclear LECs at LO is eight, not seven

In this contribution, dedicated to the memory of Walter Greiner, we discuss the structure and width of the recently established d*(2380) dibaryon, confronting the consequences of our Pion Assisted Dibaryons hadronic model with those of quark motivated calculations. In particular, its relatively small width of about 70 MeV favors hadronic structure for the d*(2380) dibaryon rather than a six-quark structure., Comment: expanded version of a talk given in a Frontiers of Science symposium dedicated to the memory of Walter Greiner, at FIAS (Frankfurt) June 2017, to be published in a special FoS volume

Recent studies of $\eta$ nuclear quasibound states by the Jerusalem-Prague Collaboration are reviewed, focusing on stochastic variational method self consistent calculations of $\eta$ few-nucleon systems. These calculations suggest that a minimum value Re$\,a_{\eta N} \approx 1$ fm (0.7 fm) is needed to bind $\eta\,^3$He ($\eta\,^4$He)., Comment: presented by A. Gal at EXA2017, Vienna, Sept. 2017; written up for EPJ Web of Conferences

$K^-$ mesons offer a unique setting where mesic atoms have been studied both experimentally and theoretically, thereby placing constraints on the possible existence and properties of meson-nuclear quasibound states. Here we review progress in this field made recently by the Jerusalem--Prague Collaboration using near-threshold $K^-N$ scattering amplitudes generated in several meson--baryon coupled channels models inspired by a chiral EFT approach. Our own procedure of handling subthreshold kinematics self consistently is used to transform these free-space energy dependent amplitudes to in-medium density dependent amplitudes from which $K^-$ optical potentials are derived. To fit the world data of kaonic atoms, these single-nucleon optical potentials are augmented by multi-nucleon terms. It is found that only two of the studied models reproduce also the single-nucleon absorption fractions available from old bubble chamber experiments. These two models are then checked for possible $K^-$ nuclear quasibound states, despite realizing that $K^-$ optical potentials are not constrained by kaonic atom data at densities exceeding half nuclear-matter density. We find that when such states exist, their widths are invariably above 100 MeV, forbiddingly large to allow observation. Multi-nucleon absorption is found to be substantial in this respect. This suggests that observable strongly bound $K^-$ mesons are limited to the very light systems, such as $K^-pp$., Comment: presented by A. Gal at Hadron2017, Sept. 2017, Salamanca, Spain; prepared for Proceedings of Science

Charge symmetry breaking (CSB) is particularly strong in the A=4 mirror hypernuclei $_{\Lambda}^4$H--$_{\Lambda}^4$He. Recent four-body no-core shell model calculations that confront this CSB by introducing $\Lambda$-$\Sigma^0$ mixing to leading-order chiral effective field theory hyperon-nucleon potentials are reviewed, and a shell-model approach to CSB in p-shell $\Lambda$ hypernuclei is outlined., Comment: presented by A. Gal at the 12th International Seminar on Nuclear Physics, Sant'Angelo d'Ischia, May 15-19 2017; prepared for J. Phys. Conf.; v2 -- slightly expanded version

Attempts to reproduce theoretically the relatively small width, $\Gamma_{d^{\ast}}=80\pm 10$ MeV, of the $I(J^P)=0(3^+)$ $d^{\ast}$(2380) dibaryon resonance established by the WASA-at-COSY Collaboration are discussed. The validity of associating the $d^{\ast}$(2380) in quark-based models primarily with a tightly bound $\Delta\Delta$ configuration is questioned. The $d^{\ast}$(2380) width and decay branching ratios into $NN\pi\pi$, $NN\pi$ and $NN$ final states are studied within the Gal-Garcilazo hadronic model in which the $d^{\ast}$(2380) is a $\pi N\Delta$ resonance embedded in the $NN\pi\pi$ continuum some 80 MeV below the $\Delta\Delta$ threshold. In particular, predictions are made for the branching ratios of the unobserved yet $d^{\ast}(2380)\to NN\pi$ decays which are suppressed in a purely-$\Delta\Delta$ dibaryon model. Comments are also made on a possible connection of the ABC effect observed in the $pn\to d^{\ast}\to d\pi^0\pi^0$ resonance reaction to the $d^{\ast}$(2380) dibaryon., Comment: v1 -- 8 pages, 3 figures, 3 tables, submitted for publication; v2 -- one review section removed, 7 pages, 2 figures, 2 tables, Physics Letters B (in press)

Several topics presented and discussed at MESON2016 are highlighted, including pentaquarks, dibaryons and meson-nuclear bound states., Comment: concluding plenary talk given at MESON2016 -- the 14th International Workshop on Meson Production, Properties and Interaction, 2nd-7th June 2016, Krak\'ow, Poland, to appear in the EPJ Web of Conferences, v2 -- references updated

Ongoing progress in understanding and evaluating charge symmetry breaking in $\Lambda$ hypernuclei is discussed in connection to recent measurements of the $_{\Lambda}^{4}{\rm H}(0^+_{\rm g.s.})$ binding energy at MAMI [A1 Collaboration: PRL 114 (2015) 232501] and of the $_{\Lambda}^{4}{\rm He}(1^+_{\rm exc})$ excitation energy at J-PARC [E13 Collaboration: PRL 115 (2015) 222501]., Comment: updated version of HYP 2015 invited talk; a slightly edited v2 to be published in the Japan Physical Society Conference Proceedings

Charge symmetry breaking (CSB) in the $\Lambda$-nucleon strong interaction generates a charge dependence of $\Lambda$ separation energies in mirror hypernuclei, which in the case of the $A=4$ mirror hypernuclei $0^+$ ground states is sizable, $\Delta B^{J=0}_{\Lambda}\equiv B^{J=0}_{\Lambda} (_{\Lambda}^4{\rm He}) -B^{J=0}_{\Lambda}(_{\Lambda}^4{\rm H})=230\pm 90$ keV, and of opposite sign to that induced by the Coulomb repulsion in light hypernuclei. Recent ab-initio calculations of the ($_{\Lambda}^4{\rm H},{_{\Lambda}^4{\rm He}}$) mirror hypernuclei $0^+_{\rm g.s.}$ and $1^+_{\rm exc}$ levels have demonstrated that a $\Lambda - \Sigma^0$ mixing CSB model due to Dalitz and von Hippel (1964) is capable of reproducing this large value of $\Delta B^{J=0}_{\Lambda}$. These calculations are discussed here with emphasis placed on the leading-order chiral EFT hyperon-nucleon strong-interaction Bonn-Juelich potential model used and the no-core shell-model calculational scheme applied. The role of one-pion exchange in producing sizable CSB level splittings in the $A=4$ mirror hypernuclei is discussed., Comment: this v4 version matches the version published in the NPA Special Issue on Recent Progress in Strangeness and Charm in Hadronic and Nuclear Physics, plus (i) an added footnote #4 on OPE CSB contributions, and (ii) an added Appendix A on the present NCSM application to hypernuclei

We report on ab-initio NCSM calculations of the A=4 mirror Lambda hypernuclei Lambda-4H and Lambda-4He, using the Bonn-Juelich LO chiral EFT YN potentials plus a CSB Lambda0--Sigma0 mixing vertex. In addition to reproducing rather well the 0+ (g.s.) and 1+ (exc.) binding energies, these four-body calculations demonstrate for the first time that the observed CSB splitting of mirror levels, reaching hundreds of keV for 0+ (g.s.), can be reproduced using realistic theoretical interaction models, although with a non-negligible momentum cutoff dependence. Our results are discussed in relation to recent measurements of the Lambda-4H (0+ g.s.) binding energy [MAMI A1 Collaboration, Phys. Rev. Lett. 114, 232501 (2015)] and the Lambda-4He (1+ exc.) excitation energy [J-PARC E13 Collaboration, Phys. Rev. Lett. 115, 222501 (2015)]., Comment: v4 matches PRL publication, also updating Ref. [30], with more details and further discussion relegated to arXiv:1604.03434

We discuss a new type of L=0 positive-parity dibaryons, pion-B-B', where the dominant binding mechanism is provided by resonating p-wave pion-baryon interactions. Recent calculations of such pion assisted dibaryons are reviewed with special emphasis placed on the non-strange I(JP)=1(2+) N-Delta dibaryon D_{12}(2150) studied recently at JLab, and on the 0(3+) Delta-Delta dibaryon D_{03}(2380) discovered recently by the WASA-at-COSY Collaboration. We review recent searches by the HADES Collaboration at GSI and by the E15 and E27 Experiments at J-PARC for a strangeness S=-1 I(JP)=1/2(0-) K-pp dibaryon and perhaps also for a strange I(JP)=3/2(2+) N-Sigma(1385) pion assisted dibaryon Y_{3/2(2+)}(2270). Charm C=+1 dibaryons, predicted with these same I(JP) values, are also briefly reviewed., Comment: Presented at the Jagiellonian Symposium on Fundamental and Applied Subatomic Physics, Cracow, June 2015; matches published version

A recent lattice QCD (LQCD) calculation of $\Sigma$-$\Lambda$ mixing by the QCDSF-UKQCD Collaboration [Phys. Rev. D 91, 074512 (2015)] finds a mixing angle about half of that found from the Dalitz-von Hippel (DvH) flavor SU(3) mass formula which relates the $\Sigma$-$\Lambda$ mixing matrix element to known octet baryon mass differences and which has been used widely to evaluate charge symmetry breaking effects in $\Lambda$ hypernuclei. We show that the LQCD-calculated $\Sigma$-$\Lambda$ mixing matrix element and octet baryon masses satisfy the DvH mass formula, concluding thereby that a good LQCD evaluation of $\Sigma$-$\Lambda$ mixing requires an equally good reproduction of octet baryon mass differences which is yet to be demonstrated., Comment: matching Phys. Rev. D published version

The large charge symmetry breaking (CSB) implied by the $\Lambda$ binding energy difference $\Delta B^{4}_{\Lambda}(0^+_{\rm g.s.})\equiv B_{\Lambda}(_{\Lambda}^4$He)$-$$B_{\Lambda}(_{\Lambda}^4$H) = 0.35$\pm$0.06 MeV of the $A=4$ mirror hypernuclei ground states, determined from emulsion studies, has defied theoretical attempts to reproduce it in terms of CSB in hyperon masses and in hyperon-nucleon interactions, including one pion exchange arising from $\Lambda-\Sigma^0$ mixing. Using a schematic strong-interaction $\Lambda N\leftrightarrow\Sigma N$ coupling model developed by Akaishi and collaborators for $s$-shell $\Lambda$ hypernuclei, we revisit the evaluation of CSB in the $A=4$ $\Lambda$ hypernuclei and extend it to $p$-shell mirror $\Lambda$ hypernuclei. The model yields values of $\Delta B^{4}_{\Lambda} (0^+_{\rm g.s.})\sim 0.25$ MeV. Smaller size and mostly negative $p$-shell binding energy differences are calculated for the $A=7-10$ mirror hypernuclei, in rough agreement with the few available data. CSB is found to reduce by almost 30 keV the 110 keV $_{~\Lambda}^{10}$B g.s. doublet splitting anticipated from the hyperon-nucleon strong-interaction spin dependence, thereby explaining the persistent experimental failure to observe the $2^-_{\rm exc}\to 1^-_{\rm g.s.}$ $\gamma$-ray transition., Comment: a few clarifying statements added to v2; matches published PLB version plus a note added after publication on p.13

Experimental evidence for $I(J^P)=0(3^+)$ $\Delta\Delta$ dibaryon ${\cal D}_{03}(2370)$ has been presented recently by the WASA-at-COSY Collaboration. Here I review new hadronic-basis Faddeev calculations of $L=0$ nonstrange pion-assisted $N\Delta$ and $\Delta\Delta$ dibaryon candidates. These calculations are so far the only ones to reproduce the relatively small ${\cal D}_{03}(2370)$ width of 70--80 MeV. Predictions are also given for the location and width of ${\cal D}_{30}$, the $I(J^P)=3(0^+)$ exotic partner of ${\cal D}_{03}(2370)$. Extensions to strangeness ${\cal S}=-1$ dibaryons are briefly discussed., Comment: 8 pages, invited talk at the International Conference on Exotic Atoms and Related Topics - EXA2014, Vienna, Austria, Sept. 15-19, 2014; v2 matching published version

Correct treatment of subthreshold Kbar-N dynamics is mandatory in kaonic-atom and Kbar-nuclear bound-state calculations, as demonstrated by using in-medium chirally-based models of Kbar-N interactions. Recent studies of kaonic-atom data reveal appreciable multi-nucleon contributions. Kbar-nuclear widths larger than 50 MeV are anticipated., Comment: Invited talk by A. Gal in MESON 2014, Cracow, May-June 2014, written up for EPJ Web of Conferences, updating an earlier Conference Proceedings (arXiv:1402.3778)

Neutrino signals in electron-capture decays of hydrogen-like parent ions P in storage-ring experiments at GSI are reconsidered, with special emphasis placed on the storage-ring quasi-circular motion of the daughter ions D in two-body decays P --> D + e-neutrino. It is argued that to the extent that daughter ions are detected, these detection rates might exhibit modulations with periods of order seconds, similar to those reported in the GSI storage-ring experiments for two-body decay rates [1,2]. New dedicated experiments in storage rings, or using traps, could explore these modulations., Comment: Presented first at the EMMI-RRTF Workshop, Jena/Dornburg, July 6-9 2014, and revised substantially since then; this final arXiv version includes footnotes that were excluded from the published version

The HypHI Collaboration at GSI argued recently for a (Lambda-n-n) bound state from the observation of its two-body (t + pi-) weak-decay mode. We derive constraints from several hypernuclear systems, in particular from the A=4 hypernuclei with full consideration of (Lambda N <--> Sigma N) coupling, to rule out a bound (Lambda-n-n)., Comment: 12 pages, 4 tables; v2--extended (i) discussion of Table 4 with a new Eq.(7), (ii) discussion of CSB effects; v3 matches published version

The role played by subthreshold meson-baryon dynamics is demonstrated in kaonic-atom, Kbar-nuclear and eta-nuclear bound-state calculations within in-medium models of Kbar-N and eta-N interactions. New analyses of kaonic atom data reveal appreciable multi-nucleon contributions. Calculations of eta-nuclear bound states show, in particular, that the eta-N scattering length is not a useful indicator of whether or not eta mesons bind in nuclei nor of the widths anticipated for such states., Comment: invited talk at the Second International Symposium on Mesic Nuclei, Cracow, Sept.22-24 2013, matches published version

Three-body hadronic models with separable pairwise interactions are formulated and solved to calculate resonance masses and widths of L=0 N-Delta and Delta-Delta dibaryons using relativistic kinematics. For N-Delta, I(JP)=1(2+) and 2(1+) resonances slightly below threshold are found by solving pi-N-N Faddeev equations. For Delta-Delta, several resonances below threshold are found by solving pi-N-Delta Faddeev equations in which the N-Delta interaction is dominated by the 1(2+) and 2(1+) resonating channels. The lowest Delta-Delta dibaryon resonances found are for I(JP)=0(3+) and 3(0+), the former agreeing well both in mass and in width with the relatively narrow D_{03}(2370) resonance observed recently by the WASA-at-COSY Collaboration. Its spin-isospin symmetric partner D_{30} is predicted with mass around 2.4 GeV and width about 80 MeV., Comment: 22 pages, 4 figures, 10 tables, extension of PRL 111 (2013) 172301, to be published in the Gerry Brown Memorial issue of Nucl. Phys. A (2014)

N-Delta and Delta-Delta dibaryon candidates are discussed and related quark-based calculations are reviewed. New hadronic calculations of L=0 nonstrange dibaryon candidates are reported. For N-Delta, I(JP)=1(2+) and 2(1+) S-matrix poles slightly below threshold are found by solving pi-N-N Faddeev equations with relativistic kinematics, and for Delta-Delta several S-matrix poles below threshold are found by solving pi-N-Delta Faddeev equations with relativistic kinematics in which the N-Delta interaction is dominated by the 1(2+) and 2(1+) resonating channels. In particular, the I(JP)=0(3+) Delta-Delta dibaryon candidate D_{03}(2370) observed recently by the WASA@COSY Collaboration is naturally explained in terms of long-range physics dominated by pions, nucleons and Delta's. These calculations are so far the only ones to reproduce the relatively small width, approximately 70 MeV, of D_{03}(2370). Predictions are also made for the location and width of D_{30}, the I(JP)=3(0+) exotic partner of D_{03}(2370)., Comment: presented by Avraham Gal at HADRON 2013, the XV International Conference on Hadron Spectroscopy at Nara, Japan, Nov. 2013, matches published version, shorter by one page than v1

The D(03) dibaryon is generated dynamically as a resonance pole in a pion-nucleon-Delta' three-body model, where Delta' is a stable Delta baryon. Using separable interactions dominated by the Delta(1232) isobar for pion-nucleon and by the D(12) isobar for nucleon-Delta', where D(12) is the nucleon-Delta 2150 MeV dibaryon deduced in and constrained by 1D2 pp scattering, the model reduces to an effective two-body problem for Delta-Delta' which is solved. The mass and width of D(03) are found close to those of the I(JP)=0(3+) resonance peak observed by WASA@COSY in pion-production pn collisions at 2.37 GeV., Comment: v3 -- 5 pages, 3 figures, 3 tables, matching PRL published version (online before Oct.25 2013)

Part 2 of "Project X: Accelerator Reference Design, Physics Opportunities, Broader Impacts". In this Part, we outline the particle-physics program that can be achieved with Project X, a staged superconducting linac for intensity-frontier particle physics. Topics include neutrino physics, kaon physics, muon physics, electric dipole moments, neutron-antineutron oscillations, new light particles, hadron structure, hadron spectroscopy, and lattice-QCD calculations. Part 1 is available as arXiv:1306.5022 [physics.acc-ph] and Part 3 is available as arXiv:1306.5024 [physics.acc-ph]., Comment: 209 pp. with many figures; prepared in part for the DPF Community Summer Study; v2 corrects typos (including one author surname), adds an author, and conforms with the version being printed; v3 includes two more chapter authors in full list at the top

Recent experimental evidence presented by the FINUDA Collaboration for a particle-stable Lambda-6H has stirred renewed interest in charting domains of particle-stable neutron-rich Lambda hypernuclei, particularly for unbound nuclear cores. We have studied within a shell-model approach several neutron-rich Lambda hypernuclei in the nuclear p shell that could be formed in (pi-,K+) or in (K-,pi+) reactions on stable nuclear targets. Hypernuclear shell-model input is taken from a theoretically inspired successful fit of gamma-ray transitions in p-shell Lambda hypernuclei which includes also Lambda-N <-> Sigma-N coupling (Lambda<->Sigma coupling). The particle stability of Lambda-6H is discussed and predictions are made for binding energies of Lambda-9He, Lambda-10Li, Lambda-12Be, Lambda-14B. None of the large effects conjectured by some authors to arise from Lambda<->Sigma coupling is borne out, neither by these realistic p-shell calculations, nor by quantitative estimates outlined for heavier hypernuclei with substantial neutron excess., Comment: 15 pages, including 1 figure and 6 tables, presented at INPC2013; v4: typos corrected, matching PLB published version

A recently proposed solution of the `GSI anomaly' by spin precession of the decaying heavy ions in the magnetic field that controls their circular motion at the GSI storage ring [G. Lambiase, G. Papini, G. Scarpetta, PLB 718 (2013) 998, Ann. Phys. 332 (2013) 143] is dubious: the uncertainty in the computed electron-capture decay-rate modulation frequency is at least of order 10E(7) Hz, by far exceeding the 1 Hz modulation frequency reported in the GSI experiment., Comment: in memoriam Paul Kienle (1931-2013) who pursued the `GSI anomaly' with boundless imagination, v2--updated references

Recent studies of kaonic atoms, few-body kaonic quasibound states and kaonic nuclei are reviewed, with emphasis on implementing the subthreshold energy dependence of the Kbar-N interaction in chiral interaction models that are consistent with the SIDDHARTA K- hydrogen data. Remarks are made on the possible role of the p-wave Sigma(1385) resonance with respect to that of the s-wave Lambda(1405) resonance in searches for strangeness S=-1 dibaryons., Comment: plenary talk at HYP2012, Barcelona, October 2012, matches published version with updated and correct references

It is pointed out that the Chiral Constituent Quark Model (CCQM) interactions that bind the H dibaryon and Lambda-Lambda-3H overbind Lambda-Lambda-6He by more than 4 MeV, thus outdating the CCQM in the strangeness S=-2 sector., Comment: added Abstract to the published version

The pi-Lambda-N - pi-Sigma-N coupled-channel system with quantum numbers (Y,I,JP) = (1,3/2,2+) is studied in a relativistic three-body model, using two-body separable interactions in the dominant p-wave pion-baryon and 3S1 YN channels. Three-body equations are solved in the complex energy plane to search for quasibound-state and resonance poles, producing a robust narrow pi-Lambda-N resonance about 10 - 20 MeV below the pi-Sigma-N threshold. Viewed as a dibaryon, it is a 5S2 quasibound state consisting of Sigma(1385)-N and Delta(1232)-Y components. Comparison is made between the present relativistic model calculation and a previous, outdated nonrelativistic calculation which resulted in a pi-Lambda-N bound state. Effects of adding a Kbar-N-N channel are studied and found insignificant. Possible production and decay reactions of this (Y,I,JP)=(1,3/2,2+) dibaryon are discussed., Comment: 17 pages, 6 tables; v3 matches journal published version

The (Kbar-N-pi) system is studied using separable interactions fitted to data available on the s-wave (Kbar-N)--(pi-Y) subsystem and the p-wave (pi-N),(pi-Y),(pi-pi) and (pi-Kbar) subsystems. Three-body (Kbar-N-pi)--(pi-Y-pi) coupled channel Faddeev equations with relativistic kinematics are solved in search for quasibound poles in the complex plane, leading to a I(JP)=1(3/2-) (Kbar-N-pi) quasibound state at M ~ (1570 +/- 10) MeV and width greater than 60 MeV near the (Kbar-N-pi) threshold. A D13 Sigma(1570) resonance of molecular structure is thus predicted., Comment: 18 pages, 4 figures, 4 tables; v3--a typo corrected in Eq.(7) where the subscripts Lambda and Sigma in v2 and in the published journal version are interchanged, with none of the results and conclusions affected

Selected topics in Strangeness Nuclear Physics are reviewed: Lambda hypernuclear spectroscopy and structure, multistrangeness, and Kbar mesons in nuclei, Comment: Proceedings version of an Overview talk at New Frontiers in QCD 2010 (NFQCD10) - Exotic Hadron Systems and Dense Matter - Yukawa Institute, Kyoto, Feb. 2010; v2 updates Table II for double-Lambda hypernuclei and its discussion beyond the published journal version

I conjecture that the time modulated decay rates reported in single ion measurements of two body electron capture decay of hydrogen like heavy ions at GSI may be related to neutrino spin precession in the static magnetic field of the storage ring. These `GSI Oscillations' arise from interference between amplitudes of decay within and without the magnetic field, a scenario that requires a Dirac neutrino magnetic moment six times lower than the Borexino solar neutrino upper limit of 0.54 x 10E(-10) Bohr magneton. I also show in a way not discussed before that the time modulation associated with interference between massive neutrino amplitudes, if such interference could arise, is of a period at least four orders of magnitude shorter than reported and must average to zero given the time resolution of the GSI measurements., Comment: corrected for typos and references, outdates arXiv:0809.1213, matches journal published version

We extend the study of a JP=2+, I=3/2 pion-Lambda-nucleon quasibound state [Phys. Rev. D 78, 014013 (2008)] by solving nonrelativistic Faddeev equations, using 3S1-3D1, Lambda N - Sigma N coupled channels Chiral Quark Model local interactions, and pion-nucleon and coupled pion-Lambda - pion-Sigma separable interactions fitted to the position and decay parameters of the Delta(1232) and Sigma(1385) resonances, respectively. The results exhibit a strong sensitivity to the p-wave pion-hyperon interaction, with a pion-Lambda-nucleon quasibound state persisting over a wide range of acceptable parametrizations., Comment: references corrected, matches Phys. Rev. C version

Coupled-channel Kbar-N dynamics near threshold and its repercussions in few-body Kbar-nuclear systems are briefly reviewed, highlighting studies of a K^-pp quasibound state. In heavier nuclei, the extension of mean-field calculations to multi-Kbar nuclear and hypernuclear quasibound states is discussed. It is concluded that strangeness in finite self-bound systems is realized through hyperons, with no room for kaon condensation., Comment: Proceedings version of plenary talk at Quark Nuclear Physics (QNP09) September 2009, Beijing; matches published version

Selected topics in Strangeness Nuclear Physics are reviewed: Lambda-hypernuclear spectroscopy and structure, Sigma-hyperon nuclear interaction, multistrangeness, and anti-kaons in nuclei., Comment: Abridged version of talk at SENDAI08, International Symposium on Strangeness Nuclear and Hadronic Systems, Dec. 2008, to be published in the Proceedings, Int. J. Mod. Phys. E. Version 2: added one reference

Explicit expressions for the parity-violating s-wave and the parity-conserving p-wave contributions to pi- weak-decay rates of Lambda hypernuclei in the 1p shell are given in the weak-coupling limit, to update previous shell-model calculations and to compare with recent pi- spectra and total decay rates measured by the FINUDA Collaboration. A useful sum rule for the summed strength of Lambda_{1s} --> pi- + proton_{1p} weak decays is derived. Fair agreement between experiment and calculations is reached, using the primary s-wave amplitude and Cohen-Kurath nuclear wavefunctions. The role of the p-wave amplitude is studied in detail for Lambda-15N and found to be secondary. Previous assignments of ground-state spin-parity values are confirmed and a new assignment is made, spin-parity 3/2+ for Lambda-15N, based on the substantial suppression calculated here for spin-parity 1/2+., Comment: published version; new footnote 2 added in proof; related to recent FINUDA data, arXiv:0905.0623 [nucl-ex] submitted to Phys. Lett. B