Wave-front dynamics in systems with directional anomalous diffusion

Hernández, Damián G.; Barrio, Rafael A.; Varea, C.

doi:10.1103/physreve.74.046116

Cited by 23 publications

(37 citation statements)

References 14 publications

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“…We have studied the semileptonic and nonleptonic decays of T − bb following closely the method developed in Ref. [30]. We present here the results for the most favorable final states where T − bb might be looked for.…”

Section: Tetraquark Mass and Wave Functionmentioning

confidence: 99%

Spectroscopy, lifetime and decay modes of the Tbb− tetraquark

et al. 2020

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We present the first full-fledged study of the flavor-exotic isoscalar T − bb ≡ bbūd tetraquark with spin and parity J P = 1 + . We report accurate solutions of the four-body problem in a quark model, characterizing the structure of the state as a function of the ratio MQ/mq of the heavy to light quark masses. For such a standard constituent model, T − bb lies approximately 150 MeV below the strong decay threshold B −B * 0 and 105 MeV below the electromagnetic decay threshold B −B0 γ. We evaluate the lifetime of T − bb , identifying the promising decay modes where the tetraquark might be looked for in future experiments. Its total decay width is Γ ≈ 87 × 10 −15 GeV and therefore its lifetime τ ≈ 7.6 ps. The promising final states are B * − D * + ℓ −ν ℓ andB * 0 D * 0 ℓ −ν ℓ among the semileptonic decays, and among the nonleptonic ones. The semileptonic decay to the isoscalar J P = 0 + tetraquark T 0 bc is also relevant but it is not found to be dominant. There is a broad consensus about the existence of this tetraquark, and its detection will validate our understanding of the low-energy realizations of Quantum Chromodynamics (QCD) in the multiquark sector. * gajatee@usal.es † javier.vijande@uv.es ‡ valcarce@usal.es § j-m.richard@ipnl.in2p3.fr Hadronic physics has been much stimulated during the last two decades by the experimental discovery of several new resonances in the hidden-charm sector, resonances that are hardly accommodated in the traditional quark-antiquark or three-quark picture [1]. These are the so-called XY Z mesons and LHCb pentaquarks, which belong to the class of "exotic hadrons", although they are not flavor exotics. After several years of studies, no definite conclusion has been drawn as to whether such non-flavor exotic states correspond to multiquark structures or to hadron-hadron molecules. A similar situation was encountered in the light scalar meson sector, where a multiquark picture was first introduced [2] as an attempt to explain the inverted mass spectrum (inverted in comparison to the simple quarkantiquark structure favored by the naive quark model) exhibited by the low-lying scalar mesons, some of which were later on suggested to be meson-meson molecules [3].For years, the sector of flavor-exotic hadrons has been somewhat forgotten, as being less easily accessible than the hidden-flavor sector. However, already some decades ago, investigations on flavor-exotic multiquarks concluded that QQqq four-quark configurations become more and more deeply bound when the mass ratio M Q /m q increases [4]. There is nowadays a broad theoretical consensus about the existence of such unconventional tetraquark configurations for which all strong decays are energetically forbidden. The most promising candidate is an isoscalar tetraquark with double beauty and J P = 1 + quantum numbers, which is stable against strong and electromagnetic decays. The same conclusion about the stability of this state has been reached in a wide variety of theoretical approaches [4][5][6][7][8][9][10][11][12][13][14]. A nov...

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Section: Tetraquark Mass and Wave Functionmentioning

confidence: 99%

Spectroscopy, lifetime and decay modes of the Tbb− tetraquark

et al. 2020

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“…The propagation of fronts in a bistable superdiffusive system governed by the asymmetric model (2.6) with the reaction function (2.3) has been considered in recent studies [34,41].…”

Section: (I) Travelling Wave Solutionsmentioning

confidence: 99%

Fronts in anomalous diffusion–reaction systems

Volpert

Nec

Nepomnyashchy

2013

Phil. Trans. R. Soc. A.

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A review of recent developments in the field of front dynamics in anomalous diffusion–reaction systems is presented. Both fronts between stable phases and those propagating into an unstable phase are considered. A number of models of anomalous diffusion with reaction are discussed, including models with Lévy flights, truncated Lévy flights, subdiffusion-limited reactions and models with intertwined subdiffusion and reaction operators.

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“…In literature, one can find various calculations on some of these form factors which were obtained via different methods. Some of these methods are the light cone QCD sum rules [14,25], QCD sum rules [18,26,27], Bethe-Salpeter equation [28], perturbative QCD factorization approach [16,17], nonrelativistic QCD approach [29], covariant light-front quark model [19], covariant confined quark model [20,30], relativistic quark model [31] and nonrelativistic constituent quark model [32]. To achieve the form factors of the related transitions in full theory, we employ the three point QCD sum rule [33][34][35], which is a powerful nonperturbative method applied in many calculations, successfully.…”

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confidence: 99%

Lepton flavor universality violation in semileptonic tree level weak transitions

2019

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The recent deviations of the experimental data on some parameters of the tree-level semileptonic B and Bc mesons decays from the standard model (SM) predictions indicate considerable violations of the lepton flavor universality, and as a result possible new physics (NP) effects. To better understand the possible NP effects it is necessary to study deeply the physical quantities defining these decays from many aspects. The calculations of the physical quantities require the determinations of the hadronic form factors entering the matrix elements of the considered transitions as the main inputs. We calculate the form factors governing the tree-level Bc → J/ψlν and Bc → ηclν transitions within the QCD sum rules method. The obtained form factors are used in the calculations of the branching ratios (BRs) of the Bc → J/ψlν and Bc → ηclν transitions as well as R(J/ψ) and R(ηc). Our result on R(J/ψ) supports the present tension between the SM theory prediction and the experimental data. Our result on R(ηc) can be checked in future experiments.PACS numbers: I. INTRODUCTIONAlthough the SM provides us with many predictions consistent with the experimental observations, there exist experimental and theoretical reasons to believe that it is not the ultimate theory of nature, but an effective theory. There are many issues that cannot be addressed by the SM. Motivated by this, some new models containing new particles or new interactions are proposed trying to find answers to these problems. The signatures of these particles are simultaneously investigated in experiments. Beside the direct searches at colliders, as an indirect approach for the investigation of new physics effects, the semi-leptonic decays involving b → c and b → s transitions provide crucial testing ground. Experimental results presented by the BABAR, Belle and LHCb collaborations [1-8] have indicated serious deviations from the predictions of SM and triggered the interest on these types of decays. Naturally, the different masses of the charged leptons lead to differences in the branching ratios of the decays containing these particles. However, further deviations from predictions of the SM imply the lepton flavor universality violation (LFUV) and make the subject intriguing from the point of NP effects investigations. Because of the higher mass of the involved τ lepton, the semileptonic transitions containing τ lepton have more sensitivity to the NP effects compared to the other leptons. As a result, a deeper understanding of these transitions will be helpful to test the SM and physics beyond it and improve our knowledge about its parameters.In this respect, investigations of the ratios of the branching fractions for the tree-level semileptonic transitionswhere l is µ or e, will be helpful due to the reduction of the uncertainties coming from the hadronic transition form factors and cancellation of the Cabibbo-Kobayashi-Maskawa matrix elements. Our focus in the present study will be on B c → J/ψlν and B c → η c lν transitions as well as R(J/ψ) and R(η c ), howe...

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Wave-front dynamics in systems with directional anomalous diffusion

Cited by 23 publications

References 14 publications

Spectroscopy, lifetime and decay modes of the Tbb− tetraquark

Spectroscopy, lifetime and decay modes of the Tbb− tetraquark

Fronts in anomalous diffusion–reaction systems

Lepton flavor universality violation in semileptonic tree level weak transitions

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