Proton spectra from Non-Mesonic Weak Decay of p-shell Λ-hypernuclei and evidence for the two-nucleon induced process

Agnello, M.; Andronenkov, A.; Beer, G.; Benussi, L.; Bertani, M.; Bhang, H.; Bonomi, G.; Botta, E.; Bregant, M.; Bressani, T.; Bufalino, S.; Busso, L.; Calvo, D.; Camerini, P.; Dalena, B.; Mori, F. De; D’Erasmo, G.; Fabbri, F.; Feliciello, A.; Filippi, A.; Fiore, E. M.; Fontana, A.; Fujioka, Hiroyuki; Genova, P.; Gianotti, P.; Grion, N.; Hartmann, O.; Lenti, V.; Lucherini, V.; Marcello, S.; Maruta, T.; Mirfakhrai, N.; Montagna, P.; Morra, O.; Nagae, T.; Nakajima, D.; Outa, H.; Pace, E.; Palomba, M.; Pantaleo, A.; Panzarasa, A.; Paticchio, V.; Piano, S.; Pompili, F.; Rui, R.; Sekimoto, M.; Simonetti, G.; Toyoda, A.; Wheadon, R.; Zenoni, A.; Garbarino, G.

doi:10.1016/j.physletb.2010.02.003

Cited by 37 publications

(66 citation statements)

References 28 publications

(68 reference statements)

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“…1 are shown the theoretical results for: a) the proton kinetic energy S p (E) developed by the decay Λp → np (left panel), and b) the total neutron spectrum S nt (E), induced both by protons, Λp → np, and by neutron, Λn → nn, yielding, respectively, the spectra S p (E), and S n (E). The BNL data for 4 Λ He [31], and the KEK [32], and FINUDA [36] data for the theory strongly overestimates all the data. In turn the SPKE potential reproduces both 4 Λ He spectra quite well, but not so well in the case of 5 Λ He.…”

Section: Resultsmentioning

confidence: 99%

“…momentum P ≡ P nN = |P nN | = |p n + p N |. More, we will seize the opportunity to discuss the spectra of other two light hypernuclei, namely of 4 Λ H, and 5 Λ He, taking care of measurements done on the latter at KEK [32][33][34], and FINUDA [36]. Theoretical expressions for different NM weak decay spectra within the IPSM that are used here have been presented previously [10,[25][26][27][28][29] and will not be repeated here.…”

Section: Introductionmentioning

confidence: 99%

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Nonmesonic Weak Decay Spectra of Light Hypernuclei

Krmpotić

2014

Few-Body Syst

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The nonmesonic weak decay spectra of light hypernuclei have been evaluated in a systematic way. As theoretical framework we adopt the independent particle shell model with three different one-meson-exchange transition potentials. Good agreement with data is obtained for proton and neutron kinetic energy spectra of 4 Λ He, and 5 Λ He, when the recoil effect is considered. The coincidence spectra of proton-neutron pairs are also accounted for quite reasonably, but it was not possible to reproduce the data for the neutron-neutron pair spectra. It is suggested that the π + K meson-exchange model with soft monopole form factors could be a good starting point for describing the dynamics responsible for the decays of these two hypernuclei. The 4 Λ H spectra are also presented.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Nonmesonic Weak Decay Spectra of Light Hypernuclei

Krmpotić

2014

Few-Body Syst

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“…A detailed description of the experimental apparatus can be found in Ref. [1]. The layout figured a cylindrical symmetry arrangement; here we briefly sketch its main components moving outwards from the beam axis: the interaction/target region, composed by a barrel of 12 thin scintillator slabs (TOFINO), surrounded by an octagonal array of Si microstrips (ISIM) facing eight target tiles; the tracking device, consisting of four layers of position sensitive detectors (a decagonal array of Si microstrips (OSIM), two octagonal layers of low mass drift chambers (LMDC) and a stereo system of straw tubes (ST)) arranged in coaxial geometry; the external time of flight detector (TO-FONE), a barrel of 72 scintillator slabs.…”

Section: Introductionmentioning

confidence: 99%

Proceedings of RIKEN BNL Research Center Workshop: Hyperon-Hyperon Interactions and Searches for Exotic Di-Hyperons in Nuclear Collisions

Baltz¹,

Fries²,

Huang³

et al. 2012

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RBRC has an active workshop program on strong interaction physics with each workshop focused on a specific physics problem. In most cases all the talks are made available on the RBRC website. In addition, highlights to each speaker's presentation are collected to form proceedings which can therefore be made available within a short time after the workshop. To date there are over one hundred proceeding volumes available.A 10 teraflops RBRC QCDOC computer funded by RIKEN, Japan, was unveiled at a dedication ceremony at BNL on May 26, 2005. This supercomputer was designed and built by individuals from Columbia University, mM, BNL, RBRC, and the University of Edinburgh, with the U.S. D.O.E. Office of Science providing infrastructure support at BNL. Physics results were reported at the RBRC QCDOC Symposium following the dedication. QCDSP, a 0.6 teraflops parallel processor, dedicated to lattice QCD, was begun at the Center on February 19, 1998, was completed on August 28, 1998, and was decommissioned in 2006. It was awarded the Gordon Bell Prize for price performance in 1998. The next generation computer in this sequence, QCDCQ (400 Teraflops), is expected to be fully operational in early 2012. H-dibaryon from INTRODUCTIONThis workshop, held on February 29 through March 2,2012 at Brookhaven National Laboratory, was dedicated to the study of hyperon-hyperon interactions and searches for exotic di-hyperons in nuclear collisions. We brought together the heavy ion and hyperon physics communities to explore new physics opportunities arising from the large number of multiple hyperons produced in heavy ion collisions .. In heavy ion collisions many hyperons (Lambda, Xi, Omega and their anti-particles) are produced in each collision as a result of coalescence or recombination processes from strangeness equilibrated dense partonic matter. This provides a unique opportunity to study hyperon-hyperon interactions through their correlations in heavy ion collisions. The investigation of multi-strangeness hyperonhyperon interactions with high statistics is not feasible in any other laboratory setting. This is a potentially very rich physics area that the heavy ion community has not fully explored yet. For example, the STAR experiment can reconstruct more than several tens of thousands of LambdaLambda pairs, more than a few tens of thousands Xi-Xi pairs and a sizable number of Omega-Omega pairs from TPC data in one year of RHIC running for Au+Au collisions. A large data volume of hyperon samples is also expected from the ALICE experiment at LHC. Such a large amount of hyperon pairs will also provide unprecedented sensitivity on exotic di-hyperon searches.The workshop program covered both recent theoretical progress and experimental results. Exciting talks were presented at the workshop on: a) latest lattice QCD calculations on the hypothetical H particle b) model calculations on nucleon-nucleon, nucleon-hyperon and hyperon-hyperon interactions and the possible existence of stable di-hyperons c) hypemuclear physics and astrophysic...

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“…The dominance of the nnp-and ppn-induced decay modes originates from the relative importance of the different isospin channels in a twofold way: it is due to the isospin factors and the way in which the weak and the strong interactions weight these factors in Eqs. (5) and (7). It turns out that the exchange of vector mesons provide dominant nnp-and nppinduced contributions by the charge-exchange terms.…”

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confidence: 99%

“…Different measurements of single and coincidence spectra of the nucleons emitted in hypernuclear nonmesonic decay, by the SKS Collaboration at KEK [5,6] and the FINUDA Collaboration at LNF [7][8][9], their theoretical analysis and the many calculations incorporating: 1) complete meson-exchange weak interaction potentials (with both oneand two-meson exchange) [10][11][12][13], 2) the description of the ΛN and NN short-range correlations in terms of quark degrees of freedom [14], 3) twonucleon induced modes, ΛNN → nNN [15][16][17][18][19][20], as well as 4) nucleon final state interactions [21][22][23], have proven crucial to solve the "Γ n /Γ p puzzle", in a continuous dialogue and exchange between theory and experiment. The two-nucleon induced decay mechanism is rather well understood at present too, although the data on Γ 2 are still affected by large error bars.…”

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confidence: 99%

Nonmesonic weak decay of Λ hypernuclei: The ΛN−ΣN coupling

2017

Self Cite

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The nonmesonic weak decay of Λ hypernuclei is studied within a microscopic diagrammatic approach which is extended to include the three-nucleon induced mechanism. We adopt a nuclear matter formalism which, through the local density approximation, allows us to model finite hypernuclei, a one-meson-exchange weak transition potential and a Bonn nucleon-nucleon strong potential. One-, two-and three-nucleon induced weak decay rates are predicted for 12 Λ C by including ground state correlations up to second order in the nucleon-nucleon potential and the recoil of the residual nucleus. Three-nucleon stimulated decays, ΛN N N → nN N N (N = n or p), are considered here for the first time. The obtained decay rates compare well with the latest KEK and FINUDA data. The three-nucleon induced rate turns out to be dominated by nnp-and npp-induced decays, it amounts to ∼ 7% of the total nonmesonic rate and it is ∼ 1/2 of the neutron-induced decay rate. The reduction effect of the nuclear recoil is particularly relevant for the three-nucleon induced rates (∼ 15%), less important for the two-nucleon induced rates (∼ 4%) and negligible for the one-nucleon induced rates. Given the non-negligible size of the three-nucleon induced contribution and consequently its importance in the precise determination of the complete set of decay rates, new measurements and/or experimental analysis are encouraged. Introduction -Since the first observation of Λ hypernuclei in 1953 and the introduction of the strangeness quantum number in the same year, strange nuclei have been investigated with increasing theoretical and experimental efforts [1]. Hypernuclear physics is nowadays a mature field of research which in many aspects is located at the crossroads between particle and nuclear physics. It implies important connections with QCD [2] -consider the relevance of the production of hypernuclei and anti-hypernuclei in relativistic heavy-ion collisions and the possible extension of the usual techniques of lattice QCD, effective field theories and chiral perturbation theory to the baryon-baryon interactions in the strange sector-as well as with astrophysical processes and observables [3], where it provides important inputs to study the thermal evolution, the stability, the macroscopic properties and the composition of compact astrophysical objects, including the so-called "hyperon puzzle" in neutron stars.

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Proton spectra from Non-Mesonic Weak Decay of p-shell Λ-hypernuclei and evidence for the two-nucleon induced process

Abstract: Physics Letters B for the first time. A value for the two-nucleon stimulated decay rate to the total decay rate Γ2/ΓNMWD=0.24±0.10 is also extracted.

Cited by 37 publications

References 28 publications

Nonmesonic Weak Decay Spectra of Light Hypernuclei

Nonmesonic Weak Decay Spectra of Light Hypernuclei

Proceedings of RIKEN BNL Research Center Workshop: Hyperon-Hyperon Interactions and Searches for Exotic Di-Hyperons in Nuclear Collisions

Nonmesonic weak decay of Λ hypernuclei: The ΛN−ΣN coupling

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