Multi-\bar K configurations and the limit of kaon condensation

Our recent relativistic mean-field (RMF) calculations of multi?-? $\bar K$ nuclei are briefly reviewed. I discuss the saturation pattern of the $\bar K$ separation energy $B_{\bar K}$ and nuclear densities on increasing the number of antikaons embedded in the nuclear medium. Saturation appears to be a robust feature of multi- $\bar K$ nuclei. Because $B_{\bar K}$ generally does not exceed 200 MeV, it is unlikely that kaon condensation occurs in strong-interaction self-bound strange hadronic matter. Last, I present our calculations of self-bound strange systems made out of neutrons and ${\bar K}^0$ mesons.     

Reaction pp \rightarrow pp \pi \pi \pi as a background for hadronic decays of the \eta^{{\prime}}_{} meson

Isospin violating hadronic decays of the $ \eta$ and $ \eta{^\prime}$ mesons into 3 $ \pi$ mesons are driven by a term in the QCD Lagrangian proportional to the mass difference of the d and u quarks. The source giving large yield of the mesons for such decay studies are pp interactions close to the respective kinematical thresholds. The most important physics background for $ \eta$ , $ \eta{^\prime}$ $ \rightarrow$ $ \pi$ $ \pi$ $ \pi$ is coming from direct three-pion production reactions. In case of the $ \eta$ meson the background for the decays is relatively low ( $ \approx$ 10% . The purpose of this article is to provide an estimate of the direct pion production background for the $ \eta{^\prime}$ $ \rightarrow$ 3 $ \pi$ decays. Using the inclusive data from the COSY-11 experiment we have extracted the differential cross-section for the pp $ \rightarrow$ pp -multipion production reactions with the invariant mass of the pions equal to the $ \eta{^\prime}$ meson mass and estimated an upper limit for the signal to background ratio for studies of the $ \eta{^\prime}$ $ \rightarrow$ $ \pi^{+}_{}$ $ \pi^{-}_{}$ $ \pi^{0}_{}$ decay.     

Radiative open charm decay of the Y(3940) , Z(3930) , X(4160) resonances

We determine the radiative decay amplitudes for the decay into D^* and $ \bar{{D}}$ $ \gamma$ , or D ^* _s and $ \bar{{D}}_{s}^{}$ $ \gamma$ of some of the charmonium-like states classified as X , Y , Z resonances, plus some other hidden charm states which are dynamically generated from the interaction of vector mesons with charm. The mass distributions as a function of the $ \bar{{D}}$ $ \gamma$ or $ \bar{{D}}_{s}^{}$ $ \gamma$ invariant mass show a peculiar behavior as a consequence of the D ^* $ \bar{{D}}^{*}_{}$ nature of these states. The experimental search of these magnitudes can shed light on the nature of these states.     

Charm Production in Antiproton-Proton Annihilation

We study the production of charmed mesons (D) and baryons (?? _c ) in antiproton-proton ${(\bar{p}p)}$ annihilation close to their respective production thresholds. The elementary charm production process is described by either baryon/meson exchange or by quark/gluon dynamics. Effects of the interactions in the initial and final states are taken into account rigorously. The calculations are performed in close analogy to our earlier study on ${\bar{p}p \to \bar{\Lambda} \Lambda}$ and ${\bar{p} p \to \bar{K} K}$ by connecting the processes via SU(4) flavor symmetry. Our predictions for the ${\bar{\Lambda}_c \Lambda_c}$ production cross section are in the order of 1 to 7 mb, i.e. a factor of around 10?C70 smaller than the corresponding cross sections for ${\bar{\Lambda} \Lambda}$ However, they are 100 to 1000 times larger than predictions of other model calculations in the literature. On the other hand, the resulting cross sections for ${\bar{D} D}$ production are found to be in the order of 10^?2 ?C 10^?1 ??b and they turned out to be comparable to those obtained in other studies.     

Physics beyond the Standard Model through b → s μ ?+? μ ? transition

A comprehensive study of the impact of new-physics operators with different Lorentz structures on decays involving the b ?? s ?? ^?+? ?? ^? transition is performed. The effects of new vector?Caxial vector (VA), scalar?Cpseudoscalar (SP) and tensor (T) interactions on the differential branching ratios, forward?Cbackward asymmetries (A _FB??s), and direct CP asymmetries of ${\bar B}_{\rm s}^0 \to \mu^+ \mu^-$ , ${\bar B}_{\rm d}^0 \to$ $ X_{\rm s} \mu^+ \mu^-$ , ${\bar B}_{\rm s}^0 \to \mu^+ \mu^- \gamma$ , ${\bar B}_{\rm d}^0 \to {\bar K} \mu^+ \mu^-$ , and ${\bar B}_{\rm d}^0\to {\bar{K}^*} \mu^+ \mu^-$ are examined. In ${\bar B}_{\rm d}^0\to {\bar{K}^*} \mu^+ \mu^-$ , we also explore the longitudinal polarization fraction f _L and the angular asymmetries $A_{\rm T}^{(2)}$ and A _LT, the direct CP asymmetries in them, as well as the triple-product CP asymmetries $A_{\rm T}^{\rm (im)}$ and $A^{\rm (im)}_{\rm LT}$ . While the new VA operators can significantly enhance most of the observables beyond the Standard Model predictions, the SP and T operators can do this only for A _FB in ${\bar B}_{\rm d}^0 \to {\bar K} \mu^+ \mu^-$ .     

\bar pp-Annihilation processes in the tree approximation of SU(3) chiral effective theory

The $\bar pp$ -annihilation reactions $\bar pp \to \eta \eta \eta$ and $\bar pp \to \eta {\rm K}\bar {\rm K}$ at rest are considered in the tree approximation in the framework of SU(3) chiral effective theory at leading order. The calculated branchings are compared with the data. The results for neutral (????, $\eta {\rm K}^0 \bar {\rm K}^0$ ) and charged (??K ⁺ K ^?) channels are essentially different.     

Finite W-Superalgebras and Truncated Super Yangians

Let ${Y_{m|n}^{\ell}}$ be the super Yangian of general linear Lie superalgebra for ${\mathfrak{gl}_{m|n}}$ . Let ${e \in \mathfrak{gl}_{m\ell|n\ell}}$ be a “rectangular” nilpotent element and ${\mathcal{W}_e}$ be the finite W-superalgebra associated to e. We show that ${Y_{m|n}^{\ell}}$ is isomorphic to ${\mathcal{W}_e}$ .     

{\boldsymbol N}\boldsymbol{\bar N} exotics and antiprotonic atoms

The BES Collaboration measurements of J/ψ radiative decays into $ p{\bar p}$ indicate a strong enhancement at $ p {\bar p}$ threshold. In a related experiment a peak in the invariant π ^?+? π ^???η′ mass is observed. It is shown that both structures may be related to a broad $ N{\bar N}$ quasi-bound state in the $^{11}S_{0} $ wave. The existence of this state finds additional support from the antiprotonic atom level widths. It is also explained by a traditional model of $ N \bar{N} $ interactions based on G-parity transformation. The level widths in H, D and He antiprotonic atoms and the radiochemical studies of $ {\bar p}$ capture in nuclei indicate the existence of another near-threshold quasi-bound state in a P wave.     

Antihydrogen (hydrogen) atom formation

In this paper we show how the ATHENA data samples on the antihydrogen ( ${\bar{\rm H}}$ ) formation in very different conditions provide useful information on the two different possible mechanisms: the 3-body reaction ( $\bar{p}+{e^+}+{e^+}\rightarrow {\bar{\rm H}}+ e^+$ ) and the 2-body reaction ( $\bar{p}+{\rm e^+}\rightarrow {\bar{\rm H}}+{h\nu}$ ).     

A brief review of antimatter production

In this article, we present a brief review of the discoveries of kinds of antimatter particles, including positron ( $ \bar e $ ), antiproton ( $ \bar p $ ), antideuteron ( $ \bar d $ ) and antihelium-3 ( $ ^3 \overline {He} $ ). Special emphasis is put on the discovery of the antihypertriton( $ \frac{3} {\Lambda }\overline H $ ) and antihelium-4 nucleus ( $ ^4 \overline {He} $ , or $ \bar \alpha $ ) which were reported by the RHIC-STAR experiment very recently. In addition, brief discussions about the effort to search for antinuclei in cosmic rays and study of the longtime confinement of the simplest antimatter atom, antihydrogen are also given. Moreover, the production mechanism of anti-light nuclei is introduced.     

Few-Body Approaches and Problems in Hypernuclei

It takes two nucleons to bind a Λ hyperon, and perhaps as many as three nucleons to bind two Λ hyperons. Here I review few-body calculations which consider the onset of binding in multi-strange hypernuclei, including ${\Xi}$ hyperons once the free-space strong-interaction conversion ${\Xi N \to \Lambda \Lambda}$ becomes Pauli forbidden in Λ-abundant matter. Quasibound states of ${\overline {K}}$ mesons in few-nucleon systems are also briefly discussed.     

Analysis of the \frac{1} {2}^ - and \frac{3} {2}^ - heavy and doubly heavy baryon states with QCD sum rules

In this article, we study the $\frac{1} {2}^ -$ and $\frac{3} {2}^ -$ heavy and doubly heavy baryon states $\Sigma _Q \left( {\frac{1} {2}^ - } \right)$ , $\Xi '_Q \left( {\frac{1} {2}^ - } \right)$ , $\Omega _Q \left( {\frac{1} {2}^ - } \right)$ , $\Xi _{QQ} \left( {\frac{1} {2}^ - } \right)$ , $\Omega _{QQ} \left( {\frac{1} {2}^ - } \right)$ , $\Sigma _Q^* \left( {\frac{3} {2}^ - } \right)$ , $\Xi _Q^* \left( {\frac{3} {2}^ - } \right)$ , $\Omega _Q^* \left( {\frac{3} {2}^ - } \right)$ , $\Xi _{QQ}^* \left( {\frac{3} {2}^ - } \right)$ and $\Omega _{QQ}^* \left( {\frac{3} {2}^ - } \right)$ by subtracting the contributions from the corresponding $\frac{1} {2}^ +$ and $\frac{3} {2}^ +$ heavy and doubly heavy baryon states with the QCD sum rules in a systematic way, and make reasonable predictions for their masses.     

{\Xi} Hypernucler States Predicted by the New Interaction Model ESC08c

The features of the new interaction model ESC08c in ${\Lambda N}$ , ${\Sigma N}$ and ${\Xi N}$ channels are demonstrated single hyperon potentials ${U_Y(Y=\Lambda, \Sigma, \Xi)}$ in nuclear matter on the basis of the G-matrix theory. (K ^?, K ⁺) productions of ${\Xi}$ hypernuclei are studied with ${\Xi}$ -nucleus folding potentials.     

Ultraheavy Yukawa-bound states of fourth-generation at Large Hadron Collider

A study of bound states of the fourth-generation quarks in the range of 500?C700 GeV is presented, where the binding energies are expected to be mainly of Yukawa origin, with QCD subdominant. Near degeneracy of their masses exhibits a new ??isospin??. The production of a colour-octet, isosinglet vector meson via $q\bar q \to \omega_8$ is the most interesting. Its leading decay modes are $\pi_8^\pm W^\mp$ , $\pi_8^0Z^0$ , and constituent quark decay, with $q\bar q$ and $t\bar t'$ and $b\bar b'$ subdominant. The colour octet, isovector pseudoscalar ?? ₈ meson decays via constituent quark decay, or to Wg. This work calls for more detailed study of fourth-generation phenomena at LHC.     

A new analysis improving the evidence of a narrow peak in the invariant-mass distribution of the \Lambdap system observed in the \bar{{p}} annihilation at rest on 4He

The presence of a narrow peak in the $ \Lambda$ p invariant-mass distribution observed in the $ \bar{{p}}$ annihilation reaction at rest $\ensuremath \bar{p} {}^4\mathrm{He}\rightarrow p\pi^-p\pi^+\pi^-n X$ is discussed again through an analysis procedure which improves the ratio signal/background in comparison with the previous analysis. The peak is centred at 2223.2±3.2_stat±1.2_syst MeV and has a statistical significance of 4.7 $ \sigma$ , values compatible with those published previously. If interpreted as the result of the decay into $ \Lambda$ p of a $\ensuremath { }_{\bar{K}}{}^2\mathrm{H}$ bound system, the corresponding binding energy should be B = - 151.0±3.2_stat±1.2_syst MeV and the width $ \Gamma_{{FWHM}}^{}$ < 33.9±6.2 MeV. The production rate has a lower limit of 1.2 10^-4. Data on the $ \bar{{p}}$ annihilation reaction at rest $ \bar{{p}}$ ⁴He $ \rightarrow$ p $ \pi^{-}_{}$ p $ \pi^{-}_{}$ p _s X , analyzed for the first time, lead to a result in qualitative agreement with the previous one.     

Haag Duality and the Distal Split Property for Cones in the Toric Code

We prove that Haag duality holds for cones in the toric code model. That is, for a cone ??, the algebra ${\mathcal{R}_{\Lambda}}$ of observables localized in ?? and the algebra ${\mathcal{R}_{\Lambda^c}}$ of observables localized in the complement ?? ^c generate each other??s commutant as von Neumann algebras. Moreover, we show that the distal split property holds: if ${\Lambda_1 \subset \Lambda_2}$ are two cones whose boundaries are well separated, there is a Type I factor ${\mathcal{N}}$ such that ${\mathcal{R}_{\Lambda_1} \subset \mathcal{N} \subset \mathcal{R}_{\Lambda_2}}$ . We demonstrate this by explicitly constructing ${\mathcal{N}}$ .     

Large N approach to Kaon decays and mixing 28 years later: \Delta I=1/2 rule, \hat{B}_K,and \Delta M_K

We review and update our results for $K\rightarrow \pi \pi $ decays and $K^0$ – $\bar{K}^0$ mixing obtained by us in the 1980s within an analytic approximate approach based on the dual representation of QCD as a theory of weakly interacting mesons for large $N$ , where $N$ is the number of colors. In our analytic approach the Standard Model dynamics behind the enhancement of $\hbox {Re}A_0$ and suppression of $\hbox {Re}A_2$ , the so-called $\Delta I=1/2$ rule for $K\rightarrow \pi \pi $ decays, has a simple structure: the usual octet enhancement through the long but slow quark–gluon renormalization group evolution down to the scales $\mathcal{O}(1\, {\hbox { GeV}})$ is continued as a short but fast meson evolution down to zero momentum scales at which the factorization of hadronic matrix elements is at work. The inclusion of lowest-lying vector meson contributions in addition to the pseudoscalar ones and of Wilson coefficients in a momentum scheme improves significantly the matching between quark–gluon and meson evolutions. In particular, the anomalous dimension matrix governing the meson evolution exhibits the structure of the known anomalous dimension matrix in the quark–gluon evolution. While this physical picture did not yet emerge from lattice simulations, the recent results on $\hbox {Re}A_2$ and $\hbox {Re}A_0$ from the RBC-UKQCD collaboration give support for its correctness. In particular, the signs of the two main contractions found numerically by these authors follow uniquely from our analytic approach. Though the current–current operators dominate the $\Delta I=1/2$ rule, working with matching scales $\mathcal{O}(1 \, {\hbox { GeV}})$ we find that the presence of QCD-penguin operator $Q_6$ is required to obtain satisfactory result for $\hbox {Re}A_0$ . At NLO in $1/N$ we obtain $R=\hbox {Re}A_0/\hbox {Re}A_2= 16.0\pm 1.5$ which amounts to an order of magnitude enhancement over the strict large $N$ limit value $\sqrt{2}$ . We also update our results for the parameter $\hat{B}_K$ , finding $\hat{B}_K=0.73\pm 0.02$ . The smallness of $1/N$ corrections to the large $N$ value $\hat{B}_K=3/4$ results within our approach from an approximate cancelation between pseudoscalar and vector meson one-loop contributions. We also summarize the status of $\Delta M_K$ in this approach.     

Analytic Binding Energies for Two-Baryon Bound States in 2 + 1 Strongly Coupled Lattice QCD With Two-Flavors

We consider a lattice SU(3) QCD model in 2 + 1 dimensions, with two flavors and 2 × 2 spin matrices. An imaginary time functional integral formulation with Wilson’s action is used in the strong coupling regime, i.e. small hopping parameter ${0 < \kappa \ll 1}$ , and much smaller plaquette coupling ${\beta, 0 < \beta \ll \kappa}$ . In this regime, it is known that the low-lying energy-momentum spectrum contains isolated dispersion curves identified with baryons and mesons with asymptotic masses ${m\approx-3\ln\kappa}$ and ${m_m\approx-2\ln\kappa}$ , respectively. We prove the existence of two (labelled by ±) two-baryon bound states for each of the total isospin sectors I = 0,1 and we obtain, in each case, the exact binding energies ${\epsilon_{I\,\pm} }$ (of order ${\kappa^2}$ ) which extend to jointly analytic function in ${\kappa}$ and β. We also prove that these points are the only mass spectrum up to slightly above the bound state masses. Precisely, we show, for ${\alpha_0=\frac 14, \alpha_1=\frac 1{12}, \alpha_2=\frac12, \alpha_3=\frac 34}$ and small ${\delta >0 }$ , that the bound state masses ${2m-\epsilon_{I\,\pm}}$ are the only points in the mass spectrum in ${(0,2m-\epsilon_{I\,\pm}+\delta \alpha_I\kappa^2)}$ , for I = 0,1, and in ${(0,2m-(1+\delta)\alpha_I\kappa^2)}$ , for I = 2,3. These results are exact and validate our previous results obtained in a ladder approximation. The method employs suitable two- and four-point correlations with spectral representations and a lattice Bethe-Salpeter equation. For I = 0,1, a quark, antiquark space-range one potential of order ${\kappa^2}$ is found to be the dominant contribution to the two-baryon interaction and the interaction of the individual quark isospins of one baryon with those of the other is described by permanents. A novel spectral free decomposition (but spectral representation motivated, for real κ and β) of the two-point correlation, after performing a complex extension, is a key ingredient in showing the joint analyticity of the binding energy.     

Structure of neutron-rich nuclei around the N = 126 closed shell; the yrast structure of 205Au126 up to spin-parity I^{\pi} = (19/2+)

Heavy neutron-rich nuclei have been populated through the relativistic fragmentation of a $\ensuremath ^{208}_{\ 82}{\rm Pb}$ beam at $\ensuremath E/A = 1$ GeV on a $\ensuremath 2.5 {\rm g/cm^2}$ thick Be target. The synthesised nuclei were selected and identified in-flight using the fragment separator at GSI. Approximately 300 ns after production, the selected nuclei were implanted in an $\ensuremath \sim 8$ mm thick perspex stopper, positioned at the centre of the RISING $\ensuremath \gamma$ -ray detector spectrometer array. A previously unreported isomer with a half-life $\ensuremath T_{1/2} = 163(5)$ ns has been observed in the N = 126 closed-shell nucleus $\ensuremath ^{205}_{\ 79}{\rm Au}$ . Through $ \gamma$ -ray singles and $ \gamma$ - $ \gamma$ coincidence analysis a level scheme was established. The comparison with a shell model calculation tentatively identifies the spin-parity of the excited states, including the isomer itself, which is found to be $\ensuremath I^{\pi} = (19/2^+)$ .     

Meson spectra and mass splitting of \eta_{c}^{} - J/ \psi calculated with a regularized quark potential

The complete Breit potential contains the terms of spin-spin, spin-orbit, orbit-orbit, and tensor force interactions which become singular at short distance. Most of previous calculations of the non-relativistic potential quark model considered only the spin-spin interaction and substituted the $ \delta$ (r) -function by the Gaussian or Yukawa potential in coordinate space. Recently, a method to regularize the Breit potential consists of subtracting terms that cancel the singularity at the origin but leave the intermediate- and long-distance behavior unchanged. Motivated by this work we regularize the Breit potential by multiplying the singular terms in momentum space identically by the form factor [ $ \mu^{2}_{}$ /(q ² + $ \mu^{2}_{}$ )]² of the momentum transfer q , where the screened mass μ increases with the reduced mass of the meson. With the regularized Breit potential we calculate the masses of 30 common mesons and the new $ \eta_{b}^{}$ meson. We find that the calculated masses from light to heavy mesons agree well with experimental data. The inclusion of such a dependence of the reduced mass in the potential regularization improves the spin-spin splittings of $ \eta_{c}^{}$ -J/ $ \psi$ and $ \eta_{b}^{}$ - $ \Upsilon$ (1S) . The spin-orbit and tensor force interactions in the Breit potential lead to the splittings of $ \chi_{{c0}}^{}$ , $ \chi_{{c1}}^{}$ , and $ \chi_{{c2}}^{}$ .