A new chapter appeared in the drama with the participation of Pentakvarkov. The LHCB collaboration announced the likely observation of PTNA PCC PCCs with hidden charm and quark composition C C̄ UUD (a pair of fascinated quark and antique, two U-quuities and one D-quark), which occur in the decay of the neutral baron λ0b → PCK- [1] .

The breakdown of this “lovely” baron, which has a lot of about 5620 MeV, occurs due to weak interaction (that is, an exchange of virtual W-bosone) is mainly in two types of final states, J/ψ λ* (where λ* is a baronic resonance with a strangeness of -1) and a state containing Pentaccard PC and K--Meson. Pentakvark PC is disintegrated due to strong interaction on the proton and meson J/ψ (charmonium, vector meson with a weight of 3097 MeV). An important statement of the authors is that to describe the data, it is necessary to include the λ0b collapse channel on Pentakvark PC and K--Meson.

Observation of pentacked with a mass of 4450 MeV and about 40 MAV widths seems more reliable (12 standard deviations); Observation of a lighter pentac coincee with a mass of about 4380 MeV (width of about 200 MeV) - less reliably (9 standard deviations). The likely values ​​of the spins of these pentacvarnes are 5/2 and 3/2, respectively; Plains, apparently, are opposite (options are possible).

Let me remind you that Pentakvark is a baron consisting of three quarks and a pair of quark-Antikvark-hence its name. It should be noted that the existence of pentacquarters is not prohibited by any fundamental principles, and their reliable (!) Observation would significantly enrich our ideas about the structure of the adron. Pentacding naturally occurs not only within the framework of the quark models proper, but also, for example, within the framework of topological (kiral) solitone models (in the Skirm model and its generalizations), which has been discussed since 1985 [2] . In such models, the baronic number is identified with a topological number, which characterizes the configuration of the kiral (meson) fields. The most important question is the energy (mass of peace) of these states.

Dramatic events were played around a pentacquard with positive strangeness (it is worth noting that the barion with positive strangeness can only be pentacked, as it should contain a strange antique; the strange quark has a quantum number of oddity S = –1). The relatively easy pentacvark with S = +1 was predicted in the work of 1997 by D. Dyakonov, V. Petrov and M. Polyakov, who was widely known [3] . However, this work had a number of shortcomings, criticized in the literature, and therefore the prediction of such a pentacquard with a relatively small mass, about 1540 MeV, was not at all strict. The excitement arose when in two experiments performed in Japan (the LPS collaboration, the leader - T. Nakanan) and in Russia (ITEF, Moscow, the leader - A. Dololenko), in 2003-2004, Pentakvark was discovered with positive strangeness and a mass of about 1540 MeV, in close accordance with the prediction of DPP. In total, more than ten different experiments observed such a relatively easy pentacvark over the next 2-3 years, and the reliability of observation in some experiments reached 6 standard deviations. A pentacquard with a strangeness of –2 (collaboration Na49, Cern) and fascinated pentacquard (which was not confirmed) was also announced.

After some time, the experimental situation with the observation of pentacked with a strangeness of +1 began to change in the opposite direction. In a number of experiments, the existence of this pentacked was not confirmed, sometimes in direct contradiction with the previous observations. For example, Pentakvark was not found in Japan at the same installation where it was first observed. Why this happened is still not quite clear. Apparently, the notorious human (psychological) factor played a role. One way or another, interest in this topic faded.

And now a new page has arisen in this drama, and with pentacular, having a heavy fluvor - charm, or charm. According to the authors, the observation of a heavier pentacard was crossed and quite reliably.

I note that the observation is clearly an exotic baronal state, for example, with a strangeness or charm of -1 (it should be reminded that, in accordance with the ratio of Gell -Mann -the fascinated quark has a quantum of charm, or charm, C = +1, the lovely quark, it would have a bump b = -1). The advantage compared to the observation of cryptoexzotic (that is, hidden, “encrypted” exotic [4] ) states, which are observed by the LHCB collaboration with hidden charm. The interpretation of such states still requires certain assumptions about the dynamics of the entire process, in particular, it is assumed that the rightly so-called Cweig's rule, according to which the birth of a pair of quark-antics in the reactions of strong interaction is suppressed compared to reactions in which such a couple is already present in the initial state.

We will wait for the continuation of this drama.

Photo by Iya RAS

1. Observation of J/ψ p Resonance Consistent with PentaQuark States in λ0b → J/ψ K - P Decays. LHCB Collaboration (Roel Aaij (Cern) et al.)-E-Print: Arxiv: 1507.03414 [HEP-EX].

2. Bidenharn, Dutan, 1985; Prazzhalovich M., 1987; Walliser G., 1992; Kopeliovich V., 1990. See also UFN 174 (2004) 323, where a brief overview of the pentacard situation is given at that time.

3. Cm. Petrov V. In search of pentacked // Trv-hunger, No. 125 dated March 26, 2013.

4. There are two types of exotic states: Manifestly Exotic - obviously exotic, external quantum numbers, and Cryptoexotic - cryptoexzotic (exotic in composition).

Amendment to the article "Continuation of the Pentacked Drama" by V. Kopeliovich

In Japan, the existence of a slight pentacked with a positive strangeness θ + was not confirmed in the interaction reaction of positive casons with protons on the proton synchrotron Kek-Ps [Search for theta+ Via K+ Pi+ X Reaction with a 1.2-gev/c+ Beam. Arxiv: 0712.3839 [nucl-ex]; Phys.rev. C77 (2008) 045203], and later in the reaction π-r → K-x [High-Resolations Search for the θ + PentaQuark Via A Pion -induced Reaction at J-Parc. E19 Collaboration, Arxiv: 1407.0669 [nucl-sex]; Phys.rev. C90 (2014) 3, 035205].

LPS collaboration (Laser-Electron Photon Facility at Spring-8), which announced the observation of the pentacquard θ +(1540) in 2003 in the reaction of the photographs on carbon, confirmed its existence in 2008 in the reaction of the photographic Room, at the level of reliability of 5.1 of : + in the γD → K+ K - Pn Reaction. Arxiv: 0812.1035 [nucl-ex]; Phys.rev. C79 (2009) 025210]. The author is grateful A. Dololenko and M. Polyakov, who drew attention to the error when mentioning these data in the article.