Search for the doubly charmed baryon ■

A search for the doubly charmed baryon Ξ_(cc)~+ is performed through its decay to the Λ_c~+K~-π~+ final state, using proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 Te V. The data correspond to a total integrated luminosity of 9 fb~(-1). No significant signal is observed in the mass range from 3.4 to 3.8 Ge V/c~2. Upper limits are set at 95% credibility level on the ratio of the Ξ_(cc)~+ production cross-section times the branching fraction to that of Λ_c~+ and Ξ_(cc)~(++) baryons. The limits are determined as functions of the Ξ_(cc)~+ mass for different lifetime hypotheses, in the rapidity range from 2.0 to 4.5 and the transverse momentum range from 4 to 15 GeV/c.     

Search for the doubly charmed baryon ?_(cc)~+

A search for the doubly charmed baryon ?_(cc)~+ with the decay mode ?_(cc)~+→Ξ_c~+K~-π~+ is performed using proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the LHCb experiment from 2016 to 2018, corresponding to an integrated luminosity of 5.4 fb~(-1). No significant signal is observed within the invariant mass range of 3.6 to 4.0 GeV/c~2. Upper limits are set on the ratio R of the production cross-section times the total branching fraction of the ?_(cc)~+→Ξ_c~+K~-π~+ decay with respect to the Ξ_(cc)~(++)→Λ_c~+K~-π~+π~+ decay. Upper limits at 95% credibility level for R in the range 0.005 to 0.11 are obtained for diferent hypotheses on the ?_(cc)~+ mass and lifetime in the rapidity range from 2.0 to 4.5 and transverse momentum range from 4 to 15 GeV/c.     

Search for the doubly heavy baryon ■ decaying to ■

A first search for the ■decay is performed by the LHCb experiment with a data sample of proton-proton collisions, corresponding to an integrated luminosity of 9 fb^-1 recorded at centre-of-mass energies of 7, 8, and 13 TeV. Two peaking structures are seen with a local(global) significance of 4.3(2.8) and 4.1(2.4) standard deviations at masses of 6571 and 6694 MeV/c², respectively. Upper limits are set on the ■ baryon production cross-section times the branching fraction rela...     

Observation of the Ξ(b)(0) baryon

The observation of the bottom, strange baryon Ξ(b)(0) through the decay chain Ξ(b)(0)→Ξ(c)(+)π-, where ΞΞ(c)(+)→Ξ- π+ π+, Ξ-→Λπ-, and Λ→pπ-, is reported by using data corresponding to an integrated luminosity of 4.2 fb(-1) from pp collisions at square root(s)=1.96 TeV recorded with the Collider Detector at Fermilab. A signal of 25.3(-5.4)(+5.6) candidates is observed whose probability of arising from a background fluctuation is 3.6×10(-12), corresponding to 6.8 gaussian standard deviations. The Ξ(b)(0) mass is measured to be 5787.8±5.0(stat)±1.3(syst) MeV/c2. In addition, the Ξ(b)- baryon is observed through the process Ξ(b)-→Ξ(c)(0)π-, where Ξ(c)(0)→Ξ- π+, Ξ-→Λπ-, and Λ→pπ-.     

Search for CP violation in D± meson decays to ϕπ±

We search for CP violation in Cabibbo-suppressed charged D meson decays by measuring the difference between the CP-violating asymmetries for the Cabibbo-suppressed decays D(±)→K(+)K(-)π(±) and the Cabibbo-favored decays D(s)(±)→K(+)K(-)π(±) in the K(+)K(-) mass region of the ? resonance. Using 955 fb(-1) of data collected with the Belle detector, we obtain A(CP)(D+→?π+)=(+0.51±0.28±0.05)%. The measurement improves the sensitivity of previous searches by more than a factor of 5. We find no evidence for direct CP violation.     

Search for the ϕ → π+π−γγ and ϕ → π+π−η decays with the CMD-2 detector

The ? → π⁺π^?γγ and ? → π⁺π^?η decays are sought in the experimental data obtained with the CMD-2 detector in the region of the ?-meson resonance. Upper limits ?(? → ππγγ)< 1.2 × 10^?4 and ?(? → ππη) < 6.1 × 10^?5 (both at a C.L. of 90%) are determined for the branching ratios of these decays.     

Detecting a first-order transition in the QCD phase diagram with baryon–baryon correlations

We suggest baryon–baryon correlations as an experimentally accessible signature for a first-order phase transition between a baryon-rich phase, like quarkyonic, and a baryon-suppressed hadronic phase in the QCD phase diagram. We examine the consequences of baryon-rich bubble formation in an expanding medium and show how the two-particle correlations vary in the transverse and longitudinal direction depending on the strength of the radial flow, the bubble temperature, and the time when the baryons are emitted.     

Observation of the orbitally excited Λ(1520) baryon in e+e− annihilation

We report the first observation of an orbitally excited baryon, the Λ(1520), in quark and gluon fragmentation. The production rate is found to be (1.15±0.21±0.16)×10⁻² and (0.80±0.17_−0.13^+0.10)×10⁻²Λ(1520) hyperons per event in direct ϒ decays and in the continuum, respectively. In contrast to the observed situation for ground state baryons, the production of the Λ(1520) in direct ϒ decays shows little or no enhancement with respect to continuum production.     

O(N) symmetric finite-temperatureϕ 4 theory in 2+1 dimensions

Starting from the grand partition function, the symmetry breaking of a BE gas in 2+1 dimension is investigated both analytically and numerically. For this the Gaussian effective potential method is extended to (chemical potential)-dependentO(N) finite-temperature symmetric ⁴ theory. The relevant integrals involved are evaluated in a simple and straightforward manner. The results are compared with those of others obtained by the loop expansion method.     

Search for exotic state 1~(- ) π_1(1400) at BESⅢ

The J/ψ hadronic decays provide good laboratory to search for the hybrid states with exotic quantum numbers. A full Partial Wave Analysis (PWA) is performed to the generated Monte Carlo J/ψ→ρηπ data, based on the design of BESⅢ detector, to study the sensitivity of searching for a possible exotic state at BESⅢ.     

Search for CP violation in the decays D(0)→K(S)(0)P(0)

We have searched for CP violation in the decays D(0)→K(S)(0)P(0) where P(0) denotes a neutral pseudoscalar meson that is either a π(0), η, or η' using KEKB asymmetric-energy e(+)e(-) collision data corresponding to an integrated luminosity of 791 fb(-1) collected with the Belle detector. No evidence of significant CP violation is observed. We report the most precise CP asymmetry measurement in the decay D(0)→K(S)(0)π(0) to date: A(CP)(D(0)→K(S)(0)π(0))=(-0.28±0.19±0.10)%. We also report the first measurements of CP asymmetries in the decays D(0)→K(S)(0)η and D(0)→K(S)(0)η': A(CP)(D(0)→K(S)(0)η)=(+0.54±0.51±0.16)% and A(CP)(D(0)→K(S)(0)η')=(+0.98±0.67±0.14)%, respectively.     

Description of πp→Δ(1232)π and πp→Δ(1232)ρ(770) reaction proceeding via baryon exchange mechanism

We analyze the available experimental data on the backward production processes N and N in the framework of the strong-cut Reggeized absorption model, which is based on the exchange of the baryon Regge trajectoriesN and with the associated cuts. The model describes rather well the data on the differential cross sections at incident momenta ranging from 2.15 to 20 GeV/c. An essential contribution of exchange even at small energies (E _lab of the order of a few GeV) is found. A model-independent analysis of data confirms this fenomena.     

Search for Scalar Resonance in the ωϕ System in the Pion-Nuclear Interaction at Momentum of 29 GeV/c

Physics of Atomic Nuclei - The charge-exchange reaction $${{\pi }^{ - }}p \to n\omega (783)\phi (1020)$$ , $$\omega \to {{\pi }^{ + }}{{\pi }^{ - }}{{\pi }^{0}}$$ , $$\phi \to {{K}^{ + }}{{K}^{ -...     

Search for f(J)(2220) in radiative J/ψ decays

We present a search for f(J)(2220) production in radiative J/ψ→γf(J)(2220) decays using 460 fb?1 of data collected with the BABAR detector at the SLAC PEP-II e(+)e? collider. The f(J)(2220) is searched for in the decays to K(+)K? and K(S)?K(S)?. No evidence of this resonance is observed, and 90% confidence level upper limits on the product of the branching fractions for J/ψ→γf(J)(2220) and f(J)(2220)→K(+)K?(K(S)?K(S)?) as a function of spin and helicity are set at the level of 10??, below the central values reported by the Mark III experiment.     

Search for low-energy resonances in 27Al(p, α)24Mg

The known low-energy resonances in ²⁷Al(p, γ)²⁸Si at e_R = 203, 223, 293 and 327 keV have been searched for in the ²⁷Al(p, α)²⁴Mg reaction. The observed upper limits for the resonance strength together with the results from previous work show that the MgAl cycle is not closed at all stellar temperatures of interest and that in the important temperature range near T₉ = 0.1 the (p, γ) reaction proceeds at least 100 times faster than the (p, α) reaction. The results might be of importance for the explanation of extinct ²⁶Al in meteoritic samples as well as of the 4 solar masses of ²⁶Al found in the interstellar medium via γ-astronomy.     

Search for proton-proton dibaryon resonances in the dp → (pp)n reaction

The pp mass distribution in the dp → (pp)n reaction has been measured at the deuteron momentum from 1700 to 2280 MeV/c. The results show no prominent peak which suggests the existence of dibaryon resonances in the mass range of 2000 to 2200 MeV/c².     

Experimental search for radiative decays of the pentaquark baryon Θ+(1540)

The data on the reactions K ⁺Xe → K ⁰ γX and K ⁺Xe → K ⁺ γX, obtained with the bubble chamber DIANA, have been analyzed for possible radiative decays of the Θ⁺(1540) baryon: Θ⁺ → K ⁰ pγ and Θ⁺ → K ⁺ nγ. No signals have been observed, and we derive the upper limits Γ(Θ⁺ → K ⁰ pγ)/Γ(Θ⁺ → K ⁰ p) < 0.032 and Γ(Θ⁺ → K ⁺ nγ)/Γ(Θ⁺ → K ⁺ nγ) < 0.041 which, using our previous measurement of Γ(Θ⁺ → KN) = 0.39 ± 0.10 MeV, translate to Γ(Θ⁺ → K ⁰ pγ) < 8 keV and Γ(Θ⁺ → K ⁺ nγ) < 11 keV at 90% confidence level. We have also measured the cross sections of K ⁺-induced reactions involving emission of a neutral pion: σ(K ⁺ n → K ⁰ pπ ⁰) = 68 ± 18 µb and σ(K ⁺ N → K ⁺ Nπ ⁰) = 30 ± 8 µb for incident K ⁺ momentum of 640 MeV.     

Search for the 70 keV resonance in17O(p, α)14N

A direct search for theE _R =70 keV resonance in¹⁷O(p, )¹⁴N was carried out using¹⁷O enriched Ta₂O₅ targets in combination with a 1 mA proton beam and suitable detectors of large solid angle. The observed upper limit for the resonance strength is8×10^–10 eV.Work supported in part by Deutsche Forschungsgemeinschaft (Ro429/21-2) and the Science Program SC1-0065 of the European Economic Community