Electromagnetic structure of octet baryons
A numerical simulation of quenched QCD on a 24x12x12x24 lattice at β=5.9 is used to calculate the electric and magnetic form factors of the baryon octet. General forms of the baryon interpolating fields are considered. Magnetic moments, electric radii, magnetic radii, and magnetic transition moments are extracted from the form factors. The electric properties are found to be consistent with a quark-model picture involving spin-dependent forces. The lattice results for the magnetic properties show a mass and spin dependence of the effective quark moments which is not accounted for in conventional quark models. Lattice calculations underestimate the magnitude of electric radii, magnetic radii, and magnetic moments compared to experimental measurements. The finite volume of the periodic lattice may be responsible for the discrepancies. The pattern of electromagnetic radii in the lattice results are seen to be generally reproduced in the model results that are considered. The only exception is that of Ξ- which proves to be a sensitive probe of the quark dynamics. Lattice calculations indicate a positive value for the normalized square magnetic radius in Ξ- which contrasts Skyrme model results. Ratios of the magnetic moments allow a more detailed comparison with the experimental measurements. The lattice calculations are seen to better reproduce the experimental ratios than the model calculations
A holographic model for the baryon octet
Fang, Zhen
2016-01-01
By adopting the nonlinear realization of chiral symmetry, a holographic model for the baryon octet is proposed. The mass spectra of the baryon octet and their low-lying excited states are calculated, which show good consistency with experiments. The couplings of pion to nucleons are derived in two gauges and are shown to be equivalent with each other. It also shows that only derivative couplings of pion to nucleons appear in this holographic model. The coupling constant is then calculated.
Octet-baryon masses in finite space
Ren, Xiu-Lei; Geng, Lisheng; Meng, Jie
2012-01-01
We report on a recent study of finite-volume effects on the lowest-lying octet baryon masses using the covariant baryon chiral perturbation theory up to next-to-leading order by analysing the latest $n_f = 2 + 1$ lattice QCD results from the NPLQCD Collaboration.
Octet baryon magnetic moments in light cone QCD sum rules
Aliev, T M; Özpineci, A
2002-01-01
Octet baryon magnetic moments are calculated in framework of the light cone QCD sum rules. The analysis is carried for the general form of the interpolating currents for octet baryons. A comparison of our results on the magnetic moments of octet baryons with the predictions of other approaches and experimental data is presented.
Baryon octet interactions in the Skyrme model
We calculate baryon-baryon interactions in the SU(3) octet using the Skyrme model. We employ an exact diagonalization procedure for the symmetry-breaking term in the solution of the single-baryon B=1 problem, and a product ansatz for the B=2 solutions. Qualitatively, the results resemble those obtained for the NN potentials using the product ansatz with no additional dynamical features. In particular, the central potentials for the ΛN and ΣN systems do not exhibit attraction. (orig.)
Isospin breaking in octet baryon mass splittings
Horsley, R. [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Najjar, J. [Regensburg Univ. (Germany). Institut fuer Theoretische Physik; Nakamura, Y. [RIKEN Advanced Institute for Computational Science, Kobe, Hyogo (Japan); Pleiter, D. [Forschungszentrum Juelich (Germany). Juelich Supercomputer Centre; Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Division; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Zanotti, J.M. [Adelaide Univ., SA (Australia). CSSM, School of Chemistry and Physics
2012-06-15
Using an SU(3) flavour symmetry breaking expansion in the quark mass, we determine the QCD component of the nucleon, Sigma and Xi mass splittings of the baryon octet due to up-down (and strange) quark mass differences in terms of the kaon mass splitting. Provided the average quark mass is kept constant, the expansion coefficients in our procedure can be determined from computationally cheaper simulations with mass degenerate sea quarks and partially quenched valence quarks. Both the linear and quadratic terms in the SU(3) flavour symmetry breaking expansion are considered; it is found that the quadratic terms only change the result by a few percent, indicating that the expansion is highly convergent.
Isospin breaking in octet baryon mass splittings
Using an SU(3) flavour symmetry breaking expansion in the quark mass, we determine the QCD component of the nucleon, Sigma and Xi mass splittings of the baryon octet due to up-down (and strange) quark mass differences in terms of the kaon mass splitting. Provided the average quark mass is kept constant, the expansion coefficients in our procedure can be determined from computationally cheaper simulations with mass degenerate sea quarks and partially quenched valence quarks. Both the linear and quadratic terms in the SU(3) flavour symmetry breaking expansion are considered; it is found that the quadratic terms only change the result by a few percent, indicating that the expansion is highly convergent.
Electromagnetic form factors of octet baryons in QCD
The electromagnetic form factors of octet baryons are estimated within light cone QCD sum rules method, using the most general form of the interpolating current for baryons. A comparison of our predictions on the magnetic dipole and electric form factors with the results of other approaches is performed
Constraint Analysis for the Interaction of the Vector-Meson Octet with the Baryon Octet
We describe a constraint analysis for the interaction of the vector-meson octet with the baryon octet. Applying Dirac's Hamiltonian method, we verify that the standard interaction in terms of two independent SU(3) structures is consistent at the classical level. We argue how the requirement of self consistency with respect to perturbative renormalizability may lead to relations among the renormalized coupling constants of the system
Constraint analysis for the interaction of the vector-meson octet with the baryon octet
Unal, Y; Scherer, S
2014-01-01
We describe a constraint analysis for the interaction of the vector-meson octet with the baryon octet. Applying Dirac's Hamiltonian method, we verify that the standard interaction in terms of two independent SU(3) structures is consistent at the classical level. We argue how the requirement of self consistency with respect to perturbative renormalizability may lead to relations among the renormalized coupling constants of the system.
Quark-Pauli effects in three octet-baryons
Nakamoto, C
2016-01-01
To sustain a neutron star with about two times the solar mass, multi baryons including hyperons are expected to produce repulsive effects in the interior of its high baryon-density region. To examine possible quark-Pauli repulsion among the baryons, we solve the eigenvalue problem of the quark antisymmetrizer for three octet-baryons that are described by most compact spatial configurations. We find that the Pauli blocking effect is weak in the $\\Lambda nn$ system, while it is strong in the $\\Sigma^-nn$ system. The appearance of the $\\Sigma^-$ hyperon is suppressed in the neutron star interior but no quark-Pauli repulsion effectively works for the $\\Lambda$ hyperon.
Interrelations between baryon trajectories and new mass formulas for baryon octet
In the framework of the dual analytic model the interrelations between Regge slopes and intercepts for baryon octet are obtained. The relations agree well with experiment and lead to new mass formulas for octets 1/2sup(+), 1/2sup(-) and their angular excitations
Virtual decuplet effects on octet baryon masses in covariant baryon chiral perturbation theory
Ren, Xiu-Lei; Geng, Lisheng; Meng, Jie; Toki, Hiroshi
2013-01-01
We extend a previous analysis of the lowest-lying octet baryon masses in covariant baryon chiral perturbation theory (ChPT) by explicitly taking into account the contribution of the virtual decuplet baryons. Up to next-to-next-to-next-to-leading order (N$^3$LO), the effects of these heavier degrees of freedom are systematically studied. Their effects on the light-quark mass dependence of the octet baryon masses are shown to be relatively small and can be absorbed by the available low-energy c...
Strange magnetic moments of octet baryons under SU(3) breaking
CAO Lu; WANG Biao; CHEN Hong
2012-01-01
Magnetic moments of octet baryons are parameterized to all orders of the flavor SU(3) breaking with the irreducible tensor technique in order to extract the contribution of each flavor quark to the magnetic moments of the octet baryons.The not-yet measured magnetic moment of Σ0 is predicted to be 0.649 μN.Our parameterized forms for the magnetic moments are explicitly flavor-dependent,and hence each flavor component of the magnetic moments can be evaluated directly via the flavor projection operator.It is fouud that the strange magnetic moment of the nucleon is suppressed due to the small isoscalar anomalous magnetic moment of the nucleon.In particular,the strange magnetic form factor of the nucleon turns out to be positive,(G(s)N) (0) =0.428 μN,which is consistent with recent data.
Octet baryon masses and sigma terms in covariant baryon chiral perturbation theory
Ren, Xiu-Lei; Geng, Li-Sheng; Meng, Jie
2015-01-01
We report on a recent study of the ground-state octet baryon masses and sigma terms in covariant baryon chiral perturbation theory with the extended-on-mass-shell scheme up to next-to-next-to-next-to-leading order. To take into account lattice QCD artifacts, the finite-volume corrections and finite lattice spacing discretization effects are carefully examined. We performed a simultaneous fit of all the $n_f = 2+1$ lattice octet baryon masses and found that the various lattice simulations are ...
Flavor Asymmetry of the Sea Quarks in the Baryon Octet
Koretune, Susumu
1998-01-01
We show that the chiral $SU(n)\\otimes SU(n)$ flavor symmetry on the null-plane severely restricts the sea quarks in the baryon octet. It predicts large asymmetry for the light sea quarks $(u,d,s)$, and universality and abundance for the heavy sea quarks. Further it is shown that existence of the heavy sea quarks constrained by the same symmetry reduces the theoretical value of the Ellis-Jaffe sum rule substantially.
Borel sum rules for octet baryons in nuclear medium
Borel sum rules are examined for octet baryons in the nuclear medium. First, it is noticed that in the medium the dispersion relation is realized for the retarded correlation ΠR(ω, q2) in the energy ω. Then, ΠR(ω, q2) is split into even and odd parts of ω in order to apply the Borel transformation. The obtained Borel sum rules differ from those of previous works. The mass shifts of octet baryons are calculated in the leading order of the operator product expansion with linear density approximation for the condensates. It is found that both scalar and vector condensates of the quark field, and +q>, induce attraction to the octet baryons in the medium in contrast to the results of previous works. It is also found that |δMN| > |δMΛ| > |δMΣ| ∼ |δMΞ|. The absolute values, however, turn out to be one order of magnitude larger than those empirically known if a Borel mass of around 1 GeV is used in the present approximation. (author)
Proton spin and baryon octet axial couplings
Peripheral spin structure of the nucelon generated by the soft mesonic radiative corrections is studied within the light-cone perturbation theory. Starting with the tree-level SU(6) symmetry, we find a good description of the axial-vector couplings in β-decay of hyperons. We study the proton helicity flow from the baryonic core to the angular momentum of the pionic cloud. It is found that in the relativistic light-cone approach the spin-flip pattern is different from that in the coventional non-relativistic models. The axial-vector current matrix elements are shown to receive large corrections from beyond the conventional static limit. The important virtue of using the light-cone vertex functions of the meson-baryon Fock components of the proton is that the local gauge invariance and the energy-momentum sum rule are satisfied automatically. We infer the radius of the light-cone form factor from an analysis of the experimental data on the fragmentation of high-energy protons into nucleons and hyperons-the process dominated by stripping off the mesons of the meson-baryon Fock states. (orig.)
Polanco-Euán, E N; Sánchez-Colón, G; Bambah, B A
2016-01-01
The SU(3) octet states with baryon number B = 2, hexaquark dibaryons, are considered. Decay coupling constants sum rules for dibaryon octet into two ordinary baryon octets with ?$\\lambda_8$ first order SU(3) symmetry breaking are given. An SU(4) extension of the analysis is commented upon. Possibilities for the experimental observation of multibaryon and anti-multibaryon states are pointed out.
Quark-model interactions for complete baryon octet
Baryon-baryon interactions for the complete baryon octet (B8) are investigated in a unified framework of the resonating-group method, in which the spin-flavor SU6 quark-model wave functions are employed. Model parameters are determined to reproduce properties of the nucleon-nucleon system and the low-energy cross section data for the hyperon-nucleon interaction. We then proceed to explore B8B8 interactions in the strangeness S=-2, -3 and -4 sectors. The S-wave phase-shift behavior and total cross sections are systematically understood by 1) the spin-flavor SU6 symmetry, 2) the special role of the pion exchange and 3) the flavor symmetry breaking. (author)
Finite-volume effects on octet-baryon masses in covariant baryon chiral perturbation theory
Geng, Li-Sheng; Ren, Xiu-Lei; Martin-Camalich, J.; Weise, W.
2011-01-01
We study finite-volume effects on the masses of the ground-state octet baryons using covariant baryon chiral perturbation theory (ChPT) up to next-to-leading order by analyzing the latest $n_f=2+1$ lattice Quantum ChromoDynamics (LQCD) results from the NPLQCD collaboration. Contributions of virtual decuplet baryons are taken into account using the "consistent" coupling scheme. We compare our results with those obtained from heavy baryon ChPT and show that, although both approaches can describ...
Light-cone distribution amplitudes of the baryon octet
Bali, Gunnar S; Göckeler, Meinulf; Gruber, Michael; Hutzler, Fabian; Schäfer, Andreas; Simeth, Jakob; Söldner, Wolfgang; Sternbeck, Andre; Wein, Philipp
2015-01-01
We present results of the first ab initio lattice QCD calculation of the normalization constants and first moments of the leading twist distribution amplitudes of the full baryon octet, corresponding to the small transverse distance limit of the associated S-wave light-cone wave functions. The P-wave (higher twist) normalization constants are evaluated as well. The calculation is done using $N_f=2+1$ flavors of dynamical (clover) fermions on lattices of different volumes and pion masses down to 222 MeV. Significant SU(3) flavor symmetry violation effects in the shape of the distribution amplitudes are observed.
Baryon octet electromagnetic form factors in a confining NJL model
Carrillo-Serrano, Manuel E.; Bentz, Wolfgang; Cloët, Ian C.; Thomas, Anthony W.
2016-08-01
Electromagnetic form factors of the baryon octet are studied using a Nambu-Jona-Lasinio model which utilizes the proper-time regularization scheme to simulate aspects of colour confinement. In addition, the model also incorporates corrections to the dressed quarks from vector meson correlations in the t-channel and the pion cloud. Comparison with recent chiral extrapolations of lattice QCD results shows a remarkable level of consistency. For the charge radii we find the surprising result that rEp quark masses.
Baryon octet electromagnetic form factors in a confining NJL model
Carrillo-Serrano, Manuel E.; Bentz, Wolfgang; Cloët, Ian C.; Thomas, Anthony W.
2016-08-01
Electromagnetic form factors of the baryon octet are studied using a Nambu-Jona-Lasinio model which utilizes the proper-time regularization scheme to simulate aspects of colour confinement. In addition, the model also incorporates corrections to the dressed quarks from vector meson correlations in the t-channel and the pion cloud. Comparison with recent chiral extrapolations of lattice QCD results shows a remarkable level of consistency. For the charge radii we find the surprising result that rEp based on the dressed quark masses.
Lowest-lying octet baryon masses in covariant baryon chiral perturbation theory
Ren, Xiu-Lei; Geng, Lisheng; Meng, Jie; Toki, Hiroshi
2013-01-01
We report on a systematic study of the ground-state octet baryon masses in the covariant baryon chiral perturbation theory with the extended-on-mass-shell renormalization scheme up to next-to-next-to-next-to-leading order, taking into account the contributions of the virtual decuplet baryons. A reasonable description of the lattice results is achieved by fitting simultaneously all the publicly available $n_f = 2+1$ lattice QCD data. It confirms that the various lattice simulations are consist...
Octet baryon masses and sigma terms in covariant baryon chiral perturbation theory
Ren, Xiu-Lei; Meng, Jie
2015-01-01
We report on a recent study of the ground-state octet baryon masses and sigma terms in covariant baryon chiral perturbation theory with the extended-on-mass-shell scheme up to next-to-next-to-next-to-leading order. To take into account lattice QCD artifacts, the finite-volume corrections and finite lattice spacing discretization effects are carefully examined. We performed a simultaneous fit of all the $n_f = 2+1$ lattice octet baryon masses and found that the various lattice simulations are consistent with each other. Although the finite lattice spacing discretization effects up to $\\mathcal{O}(a^2)$ can be safely ignored, but the finite volume corrections cannot even for configurations with $M_\\phi L>4$. As an application, we predicted the octet baryon sigma terms using the Feynman-Hellmann theorem. In particular, the pion- and strangeness-nucleon sigma terms are found to be $\\sigma_{\\pi N} = 55(1)(4)$ MeV and $\\sigma_{sN} = 27(27)(4)$ MeV, respectively.
Baryon Octet Electromagnetic Form Factors in a confining NJL model
Carrillo-Serrano, Manuel E; Cloët, Ian C; Thomas, Anthony W
2016-01-01
Electromagnetic form factors of the baryon octet are studied using a Nambu--Jona-Lasinio model which utilizes the proper-time regularization scheme to simulate aspects of colour confinement. In addition, the model also incorporates corrections to the dressed quarks from vector meson correlations in the t-channel and the pion cloud. Comparison with recent chiral extrapolations of lattice QCD results shows a remarkable level of consistency. For the charge radii we find the surprising result $r_{E}^p < r_{E}^{\\Sigma^+}$ and $|r_{E}^n| < |r_{E}^{\\Xi^0}|$, whereas the magnetic radii have a pattern largely consistent with a naive expectation based on the dressed quark masses.
Sigma Terms and Strangeness Contents of Baryon Octet in Modified Chiral Perturbation Theory
In the frame work of chiral perturbation theory, a modified effective Lagrangian for meson-baryon system is constructed, where the SU(3) breaking effect for meson is considered. The difference between physical and chiral limit decay constants is taken into account. Calculated to one loop at O(p3), the sigma terms and strangeness contents of baryon octet are obtained.
Magnetic form factors of the octet baryons from lattice QCD and chiral extrapolation
We present a 2+1-flavor lattice QCD calculation of the electromagnetic Dirac and Pauli form factors of the octet baryons. The magnetic Sachs form factor is extrapolated at six fixed values of Q2 to physical pseudoscalar masses and infinite volume using a formulation based on heavy baryon chiral perturbation theory with finite-range regularization. We properly account for omitted disconnected quark contractions using a partially-quenched effective field theory formalism. The results compare well with the experimental form factors of the nucleon and the magnetic moments of the octet baryons.
Magnetic Moments of Octet Baryons in Hot and Dense Nuclear Matter
Singh, Harpreet; Dahiya, Harleen
2016-01-01
We have calculated the in-medium magnetic moments of octet baryons in the presence of hot and dense symmetric nuclear matter. Effective magnetic moments of baryons have been derived from medium modified quark masses within chiral SU(3) quark mean field model.Further, for better insight of medium modification of baryonic magnetic moments, we have considered the explicit contributions from the valence as well as sea quark effects. These effects have been successful in giving the description of baryonic magnetic moments in vacuum. The magnetic moments of baryons are found to vary significantly as a function of density of nuclear medium.
Electric form factors of the octet baryons from lattice QCD and chiral extrapolation
We apply a formalism inspired by heavy baryon chiral perturbation theory with finite-range regularization to dynamical 2+1-flavor CSSM/QCDSF/UKQCD Collaboration lattice QCD simulation results for the electric form factors of the octet baryons. The electric form factor of each octet baryon is extrapolated to the physical pseudoscalar masses, after finite-volume corrections have been applied, at six fixed values of Q2 in the range 0.2-1.3 GeV2. The extrapolated lattice results accurately reproduce the experimental form factors of the nucleon at the physical point, indicating that omitted disconnected quark loop contributions are small. Furthermore, using the results of a recent lattice study of the magnetic form factors, we determine the ratio μpGEp/GMp. This quantity decreases with Q2 in a way qualitatively consistent with recent experimental results.
Charge radii of octet and decuplet baryons in chiral constituent quark model
Neetika Sharma; Harleen Dahiya
2013-09-01
The charge radii of the spin-$\\dfrac{1}{2}^{+}$ octet and spin-$\\dfrac{3}{2}^{+}$ decuplet baryons have been calculated in the framework of chiral constituent quark model ( CQM) using a general parametrization method (GPM). Our results are not only comparable with the latest experimental studies but also agree with other phenomenological models. The effects of (3) symmetry breaking pertaining to the strangeness contribution and GPM parameters pertaining to the one-, two- and three-quark contributions have also been investigated in detail and are found to be the key parameters in understanding the non-zero values for the neutral octet $(n, \\sum^{0}, \\Xi, )$ and decuplet $(^{0}, \\sum^{*0}, \\Xi^{*0})$ baryons.
Octet baryon mass splittings from up-down quark mass differences
Horsley, R; Nakamura, Y; Pleiter, D; Rakow, P E L; Schierholz, G; Zanotti, J M
2012-01-01
Using an SU(3) flavour symmetry breaking expansion in the quark mass, we determine the QCD component of the neutron-proton, Sigma and Xi mass splittings of the baryon octet due to up-down (and strange) quark mass differences. Provided the average quark mass is kept constant, the expansion coefficients in our procedure can be determined from computationally cheaper simulations with mass degenerate sea quarks and partially quenched valence quarks. Full details and numerical results are given in ref 1.
SU(3)-flavour breaking in octet baryon masses and axial couplings
Carrillo-Serrano, Manuel E.; Cloët, Ian C.; Thomas, Anthony W.(CSSM and ARC Centre of Excellence for Particle Physics at the Tera-scale, School of Chemistry and Physics, University of Adelaide, Adelaide, SA 5005, Australia 1 1 http://www.physics.adelaide.edu.au/cssm .)
2014-01-01
The lightest baryon octet is studied within a covariant and confining Nambu--Jona-Lasinio model. By solving the relativistic Faddeev equations including scalar and axialvector diquarks, we determine the masses and axial charges for \\Delta S = 0 transitions. For the latter the degree of violation of SU(3) symmetry arising because of the strange spectator quark(s) is found to be up to 10%.
Octet-decuplet baryon mass splittings from self-consistent one-loop perturbation theory
The bag model of confined relativistic quarks in chiral-invariant interaction with scalar, pseudoscalar, vector, and pseudovector mesons, as well as gluons, is used to calculate the masses and wave functions of the spin-1/2 baryon octet and spin-3/2 decuplet, using self-consistent Brillouin-Wigner bound state perturbation theory. Chiral symmetry breaking is invoked with the sigma model. SU (6) and SU (3) symmetries are broken by the experimental meson spectrum, and a strange quark mass. Mass corrections are calculated to one loop order, limited to the baryons of the octet and decuplet and the lowest lying mesons. Encouraging results are obtained, especially for the Δ - N and the Σ - Λ splittings. Convergence and stability have not been demonstrated, but are evidently improved by the self-consistency requirement. An initial parameter tuning gives a fit to all the octet and decuplet masses within ≤0.02 GeV, at the price of choosing the bag radius, the non-strange baryon input bag mass, and the strange quark mass. Even these small discrepancies can be dramatically reduced by fine-tuning the vector meson coupling and including an instanton contribution peculiar to the Λ. (orig.)
Nonrelativistic chiral expansion and nonleptonic decays of octet and decuplet baryons
We discuss the chiral lagrangian for JP=1/2+ octet and JP=3/2+ decuplet baryons in the language of the heavy particle effective theory. We show that the effective theory qualitatively reproduces the Pauli amplitudes for the nonleptonic hyperon decays, calculated recently by Trofimenkoff. We discuss the relation of our results to nonrelativistic SU(6). We argue that we can consistently classify the meson-baryon interaction terms in lowest order in the momentum expansion according to their transformation properties under nonrelativistic SU(6). Nevertheless, the theory as a whole remains explicitly Lorentz invariant. We explain why this does not run afoul of the theorems concerning interacting relativistic SU(6) theories. We use this SU(6) classification to discuss the relation between the nonleptonic Ω- decays and the nonleptonic decays of the octet baryons. We find that the Ω- decays cannot be explained by any interaction term transforming simply under SU(6) because the nonleptonic Ω- decays do not display the pronounced ΔI=1/2 enhancement seen in the octet hyperon decays. Any explanation of the Ω- decays requires a fine tuning of the parameters in the effective theory. We speculate that this problem may point to a flaw in the basic assumption that ΔI=1/2 four-quark operators, universally enhanced by QCD, are the dominant mechanism behind the ΔS=1 nonleptonic decays. (orig.)
Instability of the hedgehog shape for the octet baryon in the chiral quark soliton model
Akiyama, S; Akiyama, Satoru; Futami, Yasuhiko
2003-01-01
In this paper the stability of the hedgehog shape of the chiral soliton is studied for the octet baryon with the SU(3) chiral quark soliton model. The strangeness degrees of freedom are treated by a simplified bound-state approach, which omits the locality of the kaon wave function. The mean field approximation for the flavor rotation is applied to the model. The classical soliton changes shape according to the strangeness. The baryon appears as a rotational band of the combined system of the deformed soliton and the kaon.
SU(3)--Breaking Effects in Axial--Vector Couplings of Octet Baryons
Gensini, P M; Gensini, Paolo M.; Violini, Galileo
1993-01-01
Present evidence on baryon axial--vector couplings is reviewed, the main emphasis being on internal consistency between asymmetry and rate data. A complete account of all {\\sl small} terms in the Standard Model description of these latter leads to {\\sl both} consistency {\\sl and} evidence for breaking of flavour SU(3) in the axial couplings of octet baryons. Talk presented at "5th Int. Sympos. on Meson--Nucleon Physics and the Structure of the Nucleon", Boulder, CO, sept. 1993. To be published in $\\pi N$ Newsletter.
Interaction of the vector-meson octet with the baryon octet in effective field theory
Unal, Y; Scherer, S
2015-01-01
We analyze the constraint structure of the interaction of vector mesons with baryons using the classical Dirac constraint analysis. We show that the standard interaction in terms of two independent SU(3) structures is consistent at the classical level. We then require the self-consistency condition of the interacting system in terms of perturbative renormalizability to obtain relations for the renormalized coupling constants at the one-loop level. As a result we find a universal interaction with one coupling constant which is the same as in the massive Yang-Mills Lagrangian of the vector-meson sector.
Axial form factors of the octet baryons in a covariant quark model
Ramalho, G.; Tsushima, K.
2016-07-01
We study the weak interaction axial form factors of the octet baryons, within the covariant spectator quark model, focusing on the dependence of four-momentum transfer squared, Q2. In our model the axial form factors GA(Q2) (axial-vector form factor) and GP(Q2) (induced pseudoscalar form factor) are calculated based on the constituent quark axial form factors and the octet baryon wave functions. The quark axial current is parametrized by the two constituent quark form factors, the axial-vector form factor gAq(Q2), and the induced pseudoscalar form factor gPq(Q2). The baryon wave functions are composed of a dominant S -state and a P -state mixture for the relative angular momentum of the quarks. First, we study in detail the nucleon case. We assume that the quark axial-vector form factor gAq(Q2) has the same function form as that of the quark electromagnetic isovector form factor. The remaining parameters of the model, the P -state mixture and the Q2 dependence of gPq(Q2), are determined by a fit to the nucleon axial form factor data obtained by lattice QCD simulations with large pion masses. In this lattice QCD regime the meson cloud effects are small, and the physics associated with the valence quarks can be better calibrated. Once the valence quark model is calibrated, we extend the model to the physical regime and use the low Q2 experimental data to estimate the meson cloud contributions for GA(Q2) and GP(Q2). Using the calibrated quark axial form factors and the generalization of the nucleon wave function for the other octet baryon members, we make predictions for all the possible weak interaction axial form factors GA(Q2) and GP(Q2) of the octet baryons. The results are compared with the corresponding experimental data for GA(0 ) and with the estimates of baryon-meson models based on S U (6 ) symmetry.
The hidden charm pentaquarks are the hidden color-octet $uud$ baryons?
Takeuchi, Sachiko
2016-01-01
The $I(J^P)={1\\over 2}({1\\over 2}^-)$, ${1\\over 2}({3\\over 2}^-)$, and ${1\\over 2}({5\\over 2}^-)$ $uudc\\overline{c}$ pentaquarks are investigated by the quark cluster model. This model, which reproduces the mass spectra of the color-singlet $S$-wave $q^3$ baryons and $q\\overline{q}$ mesons, also enables us to evaluate the quark interaction in the color-octet $uud$ configurations. It is shown that the color-octet isospin-${1\\over 2}$ spin-${3\\over 2}$ $uud$ configuration gains attraction. The $uudc\\overline{c}$ states with this configuration cause structures around the $\\Sigma_c{}^{(*)}\\overline{D}{}^{(*)}$ thresholds: one bound state, two resonances, and one large cusp are found. We argue that the negative parity pentaquark found by the LHCb experiments may be given by these structures.
Electric form factors of the octet baryons from lattice QCD and chiral extrapolation
Shanahan, P.E.; Thomas, A.W.; Young, R.D.; Zanotti, J.M. [Adelaide Univ., SA (Australia). ARC Centre of Excellence in Particle Physics at the Terascale and CSSM; Horsley, R. [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Nakamura, Y. [RIKEN Advanced Institute for Computational Science, Kobe, Hyogo (Japan); Pleiter, D. [Forschungszentrum Juelich (Germany). JSC; Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Div.; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Stueben, H. [Hamburg Univ. (Germany). Regionales Rechenzentrum; Collaboration: CSSM and QCDSF/UKQCD Collaborations
2014-03-15
We apply a formalism inspired by heavy baryon chiral perturbation theory with finite-range regularization to dynamical 2+1-flavor CSSM/QCDSF/UKQCD Collaboration lattice QCD simulation results for the electric form factors of the octet baryons. The electric form factor of each octet baryon is extrapolated to the physical pseudoscalar masses, after finite-volume corrections have been applied, at six fixed values of Q{sup 2} in the range 0.2-1.3 GeV{sup 2}. The extrapolated lattice results accurately reproduce the experimental form factors of the nucleon at the physical point, indicating that omitted disconnected quark loop contributions are small. Furthermore, using the results of a recent lattice study of the magnetic form factors, we determine the ratio μ{sub p}G{sub E}{sup p}/G{sub M}{sup p}. This quantity decreases with Q{sup 2} in a way qualitatively consistent with recent experimental results.
Parreno, Assumpta; Tiburzi, Brian C; Wilhelm, Jonas; Chang, Emmanuel; Detmold, William; Orginos, Kostas
2016-01-01
Lattice QCD calculations with background magnetic fields are used to determine the magnetic moments of the octet baryons. Computations are performed at the physical value of the strange quark mass, and two values of the light quark mass, one corresponding to the SU(3) flavor-symmetric point, where the pion mass is ~ 800 MeV, and the other corresponding to a pion mass ~ 450 MeV. The moments are found to exhibit only mild pion-mass dependence when expressed in terms of appropriately chosen magneton units---the natural baryon magneton. This suggests that simple extrapolations can be used to determine magnetic moments at the physical point, and extrapolated results are found to agree with experiment within uncertainties. A curious pattern is revealed among the anomalous baryon magnetic moments which is linked to the constituent quark model, however, careful scrutiny exposes additional features. Relations expected to hold in the large-Nc limit of QCD are studied; and, in one case, the quark model prediction is sig...
We construct the chiral Lagrangians relevant in studies of the ground-state octet baryon masses up to O(a2) by taking into account discretization effects. We calculate the masses up to O(p4) in the extended-on-mass-shell scheme. As an application, we study the latest nf = 2+1 LQCD data on the ground-state octet baryon masses from the PACS-CS, QCDSF-UKQCD, HSC, and NPLQCD Collaborations. It is shown that the discretization effects for the studied LQCD simulations are at the order of 1-2 % for lattice spacings up to 0.15 fm and the pion mass up to 500 MeV. (orig.)
Akiyama, S; Akiyama, Satoru; Futami, Yasuhiko
2006-01-01
Mesonic fluctuations around the chiral solitons are investigated in the SU(3) chiral quark soliton model. Since the soliton takes the non-hedgehog shape for the hyperons and the hedgehog one for the non-hedgehog baryons in our approach, the fluctuations also change according to the baryonic state. The quantum corrections to the masses (the Casimir energies) are estimated for the octet and decuplet baryons. The lack of the confinement in this model demands the cutoff on the energy of the fluctuations. Under the assumption that the value of the cutoff energy is $2\\times$(the lightest constituent quark mass), these calculation reproduces the masses of the baryons within 15 % error.
Extended vector meson dominance model for the baryon octet electromagnetic form factors
An unresolved issue in the present understanding of nucleon structure is the effect of hidden strangeness on electromagnetic observables such as GnE(q2). Previously, we have shown that GnE(q2) is sensitive to small φNN couplings. A complementary approach for understanding effects due to strangeness content and the Okubo-Zweig-Iizuka (OZI) rule is to investigate the electromagnetic structure of hyperons. We apply Sakurai close-quote s universality limit of the SU(3)F symmetry relations and a prescription based on the OZI rule to calculate the electromagnetic form factors of the baryon octet states (p,n,Λ,Σ+,Σ0,Σ-,Ξ0,Ξ-) within the framework of an extended vector meson dominance model. To provide additional motivation for experimental investigation, we discuss the possibility of extracting the ratio GMΛ(q2)/GMΣΛ(q2) from the Λ/Σ polarization ratio in kaon electroproduction experiments. copyright 1996 The American Physical Society
Ren, Xiu-LeiSchool of Physics and Nuclear Energy Engineering, Beihang University, 100191, Beijing, China; Geng, Li-Sheng; Meng, Jie
2014-01-01
We construct the chiral Lagrangians relevant in studies of the ground-state octet baryon masses up to (a2) by taking into account discretization effects. We calculate the masses up to (p4) in the extended-on-mass-shell scheme. As an application, we study the latest nf=2+1 LQCD data on the ground-state octet baryon masses from the PACS-CS, QCDSF-UKQCD, HSC, and NPLQCD Collaborations. It is shown that the discretization effects for the studied LQCD simulations are at the order of 1–2 % for la...
Ren, Xiu-Lei; Geng, Li-Sheng; Meng, Jie
2013-01-01
We construct the chiral Lagrangians relevant in studies of the ground-state octet baryon masses up to O(a2) by taking into account discretization effects. We calculate the masses up to O(p4) in the extended-on-mass-shell scheme. As an application, we study the latest nf=2+1 LQCD data on the ground-state octet baryon masses from the PACS-CS, QCDSF-UKQCD, HSC, and NPLQCD Collaborations. It is shown that the discretization effects for the studied LQCD simulations are at the order of 1–2 % for la...
Determination of Baryon wave functions of the ground-state octet by means of QCD sum rules
In this work we investigate the wave functions of the baryons in the ground state octet by using the QCD sum rules technique, especially referring to the formalism of Chernyak and Zhitnitsky. The moments of the quark distibution amplitudes of the proton, Σ+ and Ξ- are determined by evaluating their sum rules graphically. For the necessary algebraic calculations we have developed a computer program package based on standard REDUCE, such that the Wilson coefficients could be calculated automatically. The contributions of the quark and gluon condensates up to energy dimension 6 have been taken into account. The corresponding quark distribution amplitudes of the cited baryons are plotted. Our results do not agree with those of a paper recently published by Chernyak, Ogloblin and Zhitnitsky and show, that the effects of the SU(3)F symmetry breaking by the mass of the strange quark are unexpectedly large. The electromagnetic form factors of the considered baryons are determined for an intermediate momentum transfer of several GeV. (orig.)
The recent quark-model baryon-baryon interactions by the Kyoto-Niigata group are applied to the triton, hypertriton, 2αΛ and 2Λα systems, in which a new three-cluster Faddeev formalism, using two-cluster resonating-group method (RGM) kernels, is developed for the exact treatment of the Pauli forbidden states between clusters
Ren, Xiu-Lei [Beihang University, School of Physics and Nuclear Energy Engineering, Beijing (China); Beihang University, International Research Center for Nuclei and Particles in the Cosmos, Beijing (China); Geng, Li-Sheng [Beihang University, School of Physics and Nuclear Energy Engineering, Beijing (China); Beihang University, International Research Center for Nuclei and Particles in the Cosmos, Beijing (China); Technische Universitaet Muenchen, Physik Department, Garching (Germany); Meng, Jie [Beihang University, School of Physics and Nuclear Energy Engineering, Beijing (China); Beihang University, International Research Center for Nuclei and Particles in the Cosmos, Beijing (China); Peking University, State Key Laboratory of Nuclear Physics and Technology, School of Physics, Beijing (China); University of Stellenbosch, Department of Physics, Stellenbosch (South Africa)
2014-02-15
We construct the chiral Lagrangians relevant in studies of the ground-state octet baryon masses up to O(a{sup 2}) by taking into account discretization effects. We calculate the masses up to O(p{sup 4}) in the extended-on-mass-shell scheme. As an application, we study the latest n{sub f} = 2+1 LQCD data on the ground-state octet baryon masses from the PACS-CS, QCDSF-UKQCD, HSC, and NPLQCD Collaborations. It is shown that the discretization effects for the studied LQCD simulations are at the order of 1-2 % for lattice spacings up to 0.15 fm and the pion mass up to 500 MeV. (orig.)
Octet magnetic Moments and their sum rules in statistical model
Batra, M
2013-01-01
The statistical model is implemented to find the magnetic moments of all octet baryons. The well-known sum rules like GMO and CG sum rules has been checked in order to check the consistency of our approach. The small discrepancy between the results suggests the importance of breaking in SU(3) symmetry.
Charge specific baryon mass formulas with deformed SU_q(3) flavor symmetry
Gresnigt, Niels G
2016-01-01
The quantum group $SU_q(3)=U_q(su(3))$ is taken as a baryon flavor symmetry to derive mass sum rules for octet and decuplet baryons. Accounting for electromagnetic contributions to baryons masses to zeroth order, the new charge specific $q$-deformed octet and decuplet baryon mass formulas are accurate to 0.02% and 0.08% respectively. A new relation between the octet and decuplet baryon masses that is accurate to 1.0% is derived. An explicit formula for the Cabibbo angle, taken to be $\\frac{\\pi}{14}$, in terms of the deformation parameter $q$ and $J^P$ of the baryons is obtained.
Pion- and strangeness-baryon $\\sigma$ terms in the extended chiral constituent quark model
An, C. S.; Saghai, B.
2014-01-01
Within an extended chiral constituent quark formalism, we investigate contributions from all possible five-quark components in the octet baryons to the pion-baryon ($\\sigma_{\\pi B}$) and strangeness-baryon ($\\sigma_{s B}$) sigma terms; $B \\equiv N,~\\Lambda,~\\Sigma,~\\Xi$. The probabilities of the quark-antiquark components in the ground-state baryon octet wave functions are calculated by taking the baryons to be admixtures of three- and five-quark components, with the relevant transitions hand...
Baryon magnetic moments in the effective quark Lagrangian approach
Simonov, YA; Tjon, JA; Weda, J; Simonov, Yu A.
2002-01-01
An effective quark Lagrangian is derived from first principles through bilocal gluon field correlators. It is used to write down equations for baryons, containing both perturbative and nonperturbative fields. As a result one obtains magnetic moments of octet and decuplet baryons without the introduc
On the quark-mass dependence of baryon ground-state masses
Semke, Alexander
2010-02-17
Baryon masses of the flavour SU(3) octet and decuplet baryons are calculated in the framework of the Chiral Perturbations Theory - the effective field theory of the strong interaction. The chiral extrapolation to the higher meson (quark) masses is carried out. The comparison with the recent results on the baryon masses from lattice calculations are presented. (orig.)
On the quark-mass dependence of baryon ground-state masses
Baryon masses of the flavour SU(3) octet and decuplet baryons are calculated in the framework of the Chiral Perturbations Theory - the effective field theory of the strong interaction. The chiral extrapolation to the higher meson (quark) masses is carried out. The comparison with the recent results on the baryon masses from lattice calculations are presented. (orig.)
Renormalization of the baryon axial vector current in large-Nc chiral perturbation theory
The baryon axial vector current is considered within the combined framework of large-Nc baryon chiral perturbation theory (where Nc is the number of colors) and the baryon axial vector couplings are extracted. Loop graphs with octet and decuplet intermediate states are systematically incorporated into the analysis
Baryons in the unquenched quark model
Bijker, R; Lopez-Ruiz, M A; Santopinto, E
2016-01-01
In this contribution, we present the unquenched quark model as an extension of the constituent quark model that includes the effects of sea quarks via a $^{3}P_{0}$ quark-antiquark pair-creation mechanism. Particular attention is paid to the spin and flavor content of the proton, magnetic moments and $\\beta$ decays of octet baryons.
Li, Hao-Song; Chen, Xiao-Lin; Deng, Wei-Zhen; Zhu, Shi-Lin
2016-01-01
We have systematically investigated the magnetic moments and magnetic form factors of the decuplet baryons to the next-to-next-leading order in the framework of the heavy baryon chiral perturbation theory. Our calculation includes the contributions from both the intermediate decuplet and octet baryon states in the loops. We also calculate the charge and magnetic dipole form factors of the decuplet baryons. Our results may be useful to the chiral extrapolation of the lattice simulations of the decuplet electromagnetic properties.
Strangeness in the baryon ground states
Semke, A
2012-01-01
We compute the strangeness content of the baryon ground states based on an analysis of recent lattice simulations of the BMW, PACS, LHPC and HSC groups for the pion-mass dependence of the baryon masses. Our results rely on the relativistic chiral Lagrangian and large-$N_c$ sum rule estimates of the counter terms relevant for the baryon masses at N$^3$LO. A partial summation is implied by the use of physical baryon and meson masses in the one-loop contributions to the baryon self energies. A simultaneous description of the lattice results of the BMW, LHPC, PACS and HSC groups is achieved. We predict the pion- and strangeness sigma terms and the pion-mass dependence of the octet and decuplet ground states at different strange quark masses.
Partially quenched study of strange baryon with N{sub f}=2 twisted mass fermions
Drach, Vincent; Brinet, Mariane; Carbonell, Jaume [UJF, CNRS/IN2P3, INPG, Grenoble (FR). Lab. de Physique Subatomique et de Cosmologie] (and others)
2009-06-15
We present results on the mass of the baryon octet and decuplet using two flavors of light dynamical twisted mass fermions. The strange quark mass is fixed to its physical value from the kaon sector in a partially quenched set up. Calculations are performed for light quark masses corresponding to a pion mass in the range 270-500 MeV and lattice sizes of 2.1 fm and 2.7 fm. We check for cut-off effects and isospin breaking by evaluating the baryon masses at two different lattice spacings. We carry out a chiral extrapolation for the octet baryons and discuss results for the {omega}. (orig.)
Partially quenched study of strange baryon with Nf = 2 twisted mass fermions
Drach, V; Carbonell, J; Alexandrou, Z L C; Korzec, T; Koutsou, G; Baron, R; Guichon, P; Pène, O; Pallante, E; Reker, S; Urbach, C; Jansen, K
2008-01-01
We present results on the mass of the baryon octet and decuplet using two flavors of light dynamical twisted mass fermions. The strange quark mass is fixed to its physical value from the kaon sector in a partially quenched set up. Calculations are performed for light quark masses corresponding to a pion mass in the range 270-500 MeV and lattice sizes of 2.1 fm and 2.7 fm. We check for cut-off effects and isospin breaking by evaluating the baryon masses at two different lattice spacings. We carry out a chiral extrapolation for the octet baryons and discuss results for the Omega.
One-loop corrections to the baryon axial vector current
M A Hernández-Ruíz
2012-10-01
The symmetry breaking corrections to the pion–baryon couplings vanish to first order in $1/N_{c}$, where $N_{c}$ is the number of colours. Loop graphs with octet and decuplet intermediate states cancel to various orders in $N_{c}$ as a consequence of the large-$N_{c}$ spin-flavour symmetry of QCD baryons. The baryon axial vector current is computed at one-loop order in heavy baryon chiral perturbation theory in the large Nc limit. $1/N_{c}$ corrections in the case of $g_{A}$ in QCD are presented here.
Interaction between the skyrmions LS potential of nuclear force and potential between the octet
Investigations of the spin-orbital (LS) interaction of nuclear force in SU(2)-model are carried out. It is well-known that in LS potential is very important in nuclear force. LS potential is created by means of light π, ρ, σ and ω mesons for the pattern of meson exchange. Adiabatic potential reproduces well the property of π- and ρ-meson exchange within the Skyrme standard model. But the attraction in the intermediate region which corresponds to σ-meson exchange disappears. Adiabatic potential between the baryon octet in SU(3)-model is discussed. The advantage of Skyrme model is in the possibility to investigate systematically the properties and interactions of baryon. There are still many investigated intresting problems in baryon physics. For example interaction between nucleon and hyperon as well as problem of the existance of H-states are still open. 12 refs.; 1 fig.; 1 tab
Chiral extrapolations and strangeness in the baryon ground states
Lutz, Matthias F M
2013-01-01
We review the quark-mass dependence of the baryon octet and decuplet masses as obtained from recent lattice simulations of the BMW, PACS-CS, LHPC, HSC and QCDSF-UKQCD groups. Our discussion relies on the relativistic chiral Lagrangian and large-$N_c$ sum rule estimates of the counter terms relevant for the baryon masses at N$^3$LO. A partial summation is implied by the use of physical baryon and meson masses in the one-loop contributions to the baryon self energies. In our analysis the physical masses are reproduced exactly by means of a suitable set of linear constraints. A quantitative and simultaneous description of all lattice results is achieved in terms of a six parameter fit, where the symmetry conserving counter term that are relevant at N$^3$LO are not yet being used. For pion masses larger than 300 MeV there appears to be an approximate linear pion-mass dependence of all octet and decuplet baryon masses. We discuss the pion- and strangeness sigma terms of the baryon octet states.
We investigate the kaon production at finite temperature and baryon density by means of an effective relativistic mean-field model with the inclusion of the full octet of baryons. Kaons are considered taking into account of an effective chemical potential depending on the self-consistent interaction between baryons. The obtained results are compared with a minimal coupling scheme, calculated for different values of the anti-kaon optical potential.
Colour octet potential to three loops
Anzai, Chihaya; Smirnov, Alexander V; Smirnov, Vladimir A; Steinhauser, Matthias
2013-01-01
We consider the interaction between two static sources in the colour octet configuration and compute the potential to three loops. Special emphasis is put on the treatment of pinch contributions and two methods are applied to reduce their evaluation to diagrams without pinches.
Colour Octet Extension of 2HDM
Valencia, German
2016-01-01
In this talk we consider some aspects of the Manohar-Wise extension of the SM with a colour-octet electroweak-doublet scalar applied to 2HDM. We present theoretical constraints on the parameters of this extension to both the SM and the 2HDM and discuss related phenomenology at LHC.
Exotic charmed baryon production in ultrarelativistic heavy ion collisions
The authors investigate multi-heavy baryon formation in Au + Au collision using an extended version of the combinatoric break up model for rehadronization. A penalty factor, p, is introduced to characterize the coalescence probability of a light quark with a heavy one. At LHC energy large production rate is found for certain multi-heavy baryons and mesons such as Ωccc, Ξcc, J/Ψ and suppression for Λc, D. They speculate also on the possible existence of a heavy bottom-charm six-quark baryon. A semiclassical and a gaussian estimate reveal that the octet-octet bbb-cc configuration can be energetically favored with respect to the singlet-singlet one
This paper contains a discussion of the spectrum of the lowest-lying charm baryons and review the experimental status of the masses of charm baryons and briefly comment on theoretical attempts to understand their spectroscopy. Lifetime measurements and lifetime hierarchies suggested by the interplay of various theoretical mechanisms contributing to the decay and semileptonic decays of charm baryons are discussed. It also treats exclusive nonleptonic charm baryon decays, where there are more data to be compared to theoretical modeling, and contains a summary and an outlook on future charm baryon experiments
Staggered Heavy Baryon Chiral Perturbation Theory
Bailey, Jon A
2007-01-01
Although taste violations significantly affect the results of staggered calculations of pseudoscalar and heavy-light mesonic quantities, those entering staggered calculations of baryonic quantities have not been quantified. Here I develop staggered chiral perturbation theory in the light-quark baryon sector by mapping the Symanzik action into heavy baryon chiral perturbation theory. For 2+1 dynamical quark flavors, the masses of flavor-symmetric nucleons are calculated to third order in partially quenched and fully dynamical staggered chiral perturbation theory. To this order the expansion includes the leading chiral logarithms, which come from loops with virtual decuplet-like states, as well as terms the order of the cubed pion mass, which come from loops with virtual octet-like states. Taste violations enter through the meson propagators in loops and tree-level terms the order of the squared lattice spacing. The pattern of taste symmetry breaking and the resulting degeneracies and mixings are discussed in d...
We review the experimental and theoretical status of baryons containing one heavy quark. The charm and bottom baryon states are classified and their mass spectra are listed. The appropriate theoretical framework for the description of heavy baryons is the Heavy Quark Effective Theory, whose general ideas and methods are introduced and illustrated in specific examples. We present simple covariant expressions for the spin wave functions of heavy baryons including p-wave baryons. The covariant spin wave functions are used to determine the Heavy Quark Symmetry structure of flavour-changing current-induced transitions between heavy baryons as well as one-pion and one-photon transitions between heavy baryons of the same flavour. We discuss 1/mQ corrections to the current-induced transitions as well as the structure of heavy to light baryon transitions. Whenever possible we attempt to present numbers to compare with experiment by making use of further model-dependent assumptions as e.g. the constituent picture for light quarks. We highlight recent advances in the theoretical understanding of the inclusive decays of hadrons containing one heavy quark including polarization. For exclusive semileptonic decays we discuss rates, angular decay distributions and polarization effects. We provide an update of the experimental and theoretical status of lifetimes of heavy baryons and of exclusive nonleptonic two body decays of charm baryons. (orig.)
Non-forward colour octet BFKL kernel
The contribution to the kernel of the non-forward BFKL equation from the two-gluon production is calculated for the case of the antisymmetric colour octet state of the Reggeized gluon in the t-channel. The one-gluon contribution to the kernel in the one-loop approximation is also obtained using the one-loop expression for the effective vertex of the one-gluon production in the Reggeon-Reggeon collisions. The explicit form of the BFKL equation total kernel is presented
Composite Octet Searches with Jet Substructure
Bai, Yang; /SLAC; Shelton, Jessie; /Yale U.
2012-02-14
Many new physics models with strongly interacting sectors predict a mass hierarchy between the lightest vector meson and the lightest pseudoscalar mesons. We examine the power of jet substructure tools to extend the 7 TeV LHC sensitivity to these new states for the case of QCD octet mesons, considering both two gluon and two b-jet decay modes for the pseudoscalar mesons. We develop both a simple dijet search using only the jet mass and a more sophisticated jet substructure analysis, both of which can discover the composite octets in a dijet-like signature. The reach depends on the mass hierarchy between the vector and pseudoscalar mesons. We find that for the pseudoscalar-to-vector meson mass ratio below approximately 0.2 the simple jet mass analysis provides the best discovery limit; for a ratio between 0.2 and the QCD-like value of 0.3, the sophisticated jet substructure analysis has the best discovery potential; for a ratio above approximately 0.3, the standard four-jet analysis is more suitable.
Signatures of color-octet quarkonium production
Beneke, M.
1996-05-01
Quarkonium spectroscopy, decay and production has provided scientists with an interesting place to test their ideas on QCD ever since charmonium was discovered in 1974. Yet, the potential of perturbative QCD (PQCD) to treat production and decay has been fully exploited only recently in a development comparable to that of Heavy Quark Effective Theory for heavy-light mesons. About the same time, experiments measuring quarkonium production at large transverse momentum have confronted theorists with surprisingly large cross sections. These observations have led to the understanding that fragmentation and hadronization of color-octet quark-antiquark (Q{anti Q}) pairs are essential in the production process. Color-octet mechanisms were considered in quarkonium decays already a while ago. They were found to solve the problem of infrared divergences in P-wave decays in a systematic way. Taking them into account also in S-wave production, where they are not required by perturbative consistency in leading order of a nonrelativistic expansion, opens the promise of a quantitative description of quarkonium production. The author briefly reviews the nonrelativistic QCD picture of quarkonium production and its confrontation with experiment in various production processes.
Scalar strangeness content of the nucleon and baryon sigma terms
Ren, Xiu-Lei; Geng, Li-Sheng; Meng, Jie
2014-01-01
The scalar strangeness content of the nucleon, characterized by the so-called strangeness-nucleon sigma term, is of fundamental importance in understanding its sea-quark flavor structure. We report a determination of the octet baryon sigma terms via the Feynman-Hellmann theorem by analyzing the latest high-statistics $n_f=2+1$ lattice QCD simulations with covariant baryon chiral perturbation theory up to next-to-next-to-next-to-leading order. In particular, we predict $\\sigma_{\\pi N}=55(1)(4)...
Kaplunovsky, Vadim; Melnikov, Dmitry; Sonnenschein, Jacob
2012-01-01
In the large N limit cold dense nuclear matter must be in a lattice phase. This applies also to holographic models of hadron physics. In a class of such models, like the generalized Sakai-Sugimoto model, baryons take the form of instantons of the effective flavor gauge theory that resides on probe flavor branes. In this paper we study the phase structure of baryonic crystals by analyzing discrete periodic configurations of such instantons. We find that instanton configurations exhibit a serie...
Charged Lepton Flavor-violating Transitions in Color Octet Model
Li, Bin; Ma, Xiao-Dong
2016-01-01
We study charged lepton flavor-violating (LFV) transitions in the color octet model that generates neutrino mass and lepton mixing at one loop. By taking into account neutrino oscillation data and assuming octet particles of TeV scale mass, we examine the feasibility to detect these transitions in current and future experiments. We find that for general values of parameters the branching ratios for LFV decays of the Higgs and $Z$ bosons are far below current and even future experimental bounds. For LFV transitions of the muon, the present bounds can be satisfied generally, while future sensitivities could distinguish between the singlet and triplet color-octet fermions. The triplet case could be ruled out by future $\\mu-e$ conversion in nuclei, and for the singlet case the conversion and the decays $\\mu\\to 3e,~e\\gamma$ play complementary roles in excluding relatively low mass regions of the octet particles.
Colour-octet bound states, induced by Higgs mechanism
Bladwell, S; Flambaum, V V; Kozlov, A
2012-01-01
The current limits for fourth generation quarks allows to expect their mass of the order of 500 GeV. In this mass region for quark-anti-quark pair the additional Yukawa-type attraction due to Higgs mechanism is expected to emerge. This Higgs induced attraction greatly exceeds strong interaction between quarks and leads to the formation of bound states in both colour octet $S^{(8)}$ and singlet $S^{(1)}$ states. In the key of recent works on significance of colour octet channel for production of colour singlet state of fourth generation $Q\\bar{Q}$ we calculated the binding energies for both octet and singlet states. Such attraction localizes quarks in extremely small area. Hence colour octet pair of fourth generation quarks can form the "nucleus" and together with colour neutralizing light particle that is captured by strong interaction in orbit around the nucleus, create particle, similar by its structure to Deuterium.
On the quark-mass dependence of the baryon ground-state masses
Semke, A
2011-01-01
We perform a chiral extrapolation of the baryon octet and decuplet masses in a relativistic formulation of chiral perturbation theory. A partial summation is assumed as implied by the use of physical baryon and meson masses in the one-loop diagrams. Upon a chiral expansion our results are consistent with strict chiral perturbation theory at the next-to-next-to-next-to-leading order. All counter terms are correlated by a large-$N_c$ operator analysis. Our results are confronted with recent results of unquenched three flavor lattice simulations. We adjust the parameter set to the pion-mass dependence of the nucleon and omega masses as computed by the BMW group and predict the pion-mass dependence of the remaining baryon octet and decuplet states. The current lattice simulations can be described accurately and smoothly up to pion masses of about 600 MeV. In particular we recover the recent results of HSC without any further adjustments.
Evidence for chiral logarithms in the baryon spectrum
Walker-Loud, Andre
2011-01-01
Using precise lattice QCD computations of the baryon spectrum, we present the first direct evidence for the presence of contributions to the baryon masses which are non-analytic in the light quark masses; contributions which are often denoted "chiral logarithms". We isolate the poor convergence of SU(3) baryon chiral perturbation theory to the flavor-singlet mass combination. The flavor-octet baryon mass splittings, which are corrected by chiral logarithms at next to leading order in SU(3) chiral perturbation theory, yield baryon-pion axial coupling constants D, F, C and H consistent with QCD values; the first evidence of chiral logarithms in the baryon spectrum. The Gell-Mann--Okubo relation, a flavor-27 baryon mass splitting, which is dominated by chiral corrections from light quark masses, provides further evidence for the presence of non-analytic light quark mass dependence in the baryon spectrum; we simultaneously find the GMO relation to be inconsistent with the first few terms in a taylor expansion in ...
Zero temperature properties of mesons and baryons from an extended linear sigma-model
An extended linear sigma model with mesons (q q-bar states) and baryons (qqq states) is presented. The model contains a low energy multiplet for every hadronic particle type, namely a scalar, a pseudoscalar, a vector and an axialvector nonet, a baryon octet and a baryon decuplet. The model parameters are determined through a multiparametric minimalization with the help of well known physical quantities. It is found that the considered zero temperature quantities (masses and decay widths) can be described well at tree-level and are in good agreement with the experimental data.
Rate equation network for baryon production in high energy nuclear collisions
We develop and solve a network of rate equations for the production of baryons and antibaryons in high energy nuclear collisions. We include all members of the baryon octet and decuplet and allow for transformations among them. This network is solved during a relativistic 2+1 hydrodynamical expansion of the of the hot matter created in the collision. As an application we compare to the number of protons, Λ's, negative cascades, and Ω baryons measured at midrapidity in central collisions of gold nuclei at 65 GeV per nucleon at the Relativistic Heavy Ion Collider (RHIC)
Study of decuplet baryon resonances from lattice QCD
Alexandrou, C.; Negele, J. W.; Petschlies, M.; Pochinsky, A. V.; Syritsyn, S. N.
2016-06-01
A lattice QCD study of the strong decay width and coupling constant of decuplet baryons to an octet baryon-pion state is presented. The transfer matrix method is used to obtain the overlap of lattice states with decuplet baryon quantum numbers on the one hand and octet baryon-pion quantum numbers on the other as an approximation of the matrix element of the corresponding transition. By making use of leading-order effective field theory, the coupling constants as well as the widths for the various decay channels are determined. The transitions studied are Δ →π N , Σ*→Λ π , Σ*→Σ π and Ξ*→Ξ π . We obtain results for two ensembles of Nf=2 +1 dynamical fermion configurations: one using domain wall valence quarks on a staggered sea at a pion mass of 350 MeV and a box size of 3.4 fm and a second one using domain wall sea and valence quarks at pion mass 180 MeV and box size 4.5 fm.
Large-Nc operator analysis of 2-body meson-baryon counter terms in the chiral Lagrangian
The chiral SU(3) Lagrangian with the baryon octet and decuplet fields is considered. The Q2 counter terms involving the decuplet fields are constructed. We derive the parameter correlation implied by the 1/Nc expansion at leading order in QCD.
A brief review on the theoretical and experimental situation of baryon spectroscopy is first given. Then, the radial structure of baryons, related to the ground state form factors and the baryonic compressibility, is discussed. An experiment has been performed at Saturne laboratory (France) in which for the first time a compression of the nucleon is observed, exciting the P11 (1440 MeV) resonance (Roper resonance) by α-particles. The analysis of the data indicates that this excitation covers a large fraction of the available monopole strength in the nucleon. The derived compressibility is discussed as well as the consequence for other fields, as nuclear medium effects on baryon properties, high density phenomena in nuclear collisions as well as colour transparency. In the last point the spin-flip structure of the P11 (1440 MeV) resonance is discussed. The possibility to determine isoscalar spin-flip strength by polarized deuteron scattering is contrasted with first preliminary results from photon-induced reactions studied at Mainz which indicate a non-negligible M1 excitation of the Roper resonance. (author) 10 figs., 31 refs
Heavy color-octet particles at the LHC
Chen, Chien-Yi; Freitas, Ayres; Han, Tao; Lee, Keith S. M.
2015-05-01
Many new-physics models, especially those with a color-triplet top-quark partner, contain a heavy color-octet state. The "naturalness" argument for a light Higgs boson requires that the color-octet state be not much heavier than a TeV, and thus it can be pair-produced with large cross sections at high-energy hadron colliders. It may decay preferentially to a top quark plus a top partner, which subsequently decays to a top quark plus a color-singlet state. This singlet can serve as a WIMP dark-matter candidate. Such decay chains lead to a spectacular signal of four top quarks plus missing energy. We pursue a general categorization of the color-octet states and their decay products according to their spin and gauge quantum numbers. We review the current bounds on the new states at the LHC and study the expected discovery reach at the 8-TeV and 14-TeV runs. We also present the production rates at a future 100-TeV hadron collider, where the cross sections will be many orders of magnitude greater than at the 14-TeV LHC. Furthermore, we explore the extent to which one can determine the color octet's mass, spin, and chiral couplings. Finally, we propose a test to determine whether the fermionic color octet is a Majorana particle.
Excited baryons from Bayesian priors and overlap fermions
F.X. Lee; S.J. Dong; T. Draper; I. Horvath; K.F. Liu; N. Mathur; J.B. Zhang
2003-05-01
Using the constrained-fitting method based on Bayesian priors, we extract the masses of the two lowest states of octet and decouplet baryons with both parities. The calculation is done on quenched 163 x 28 lattices of a = 0.2 fm using an improved gauge action and overlap fermions, with the pion mass as low as 180 MeV. The Roper state N(1440)+ is clearly observed for the first time as the 1st-excited state of the nucleon from the standard interpolating field. Together with other baryons, our preliminary results indicate that the level-ordering of the low-lying baryon states on the lattice is largely consistent with experiment. The realization is helped by cross-overs between the excited + and - states in the region of mp 300 to 400 MeV.
The status of the theory of the low-energy approach to hadron structure is reviewed briefly by surveying a few relevant models. A few examples of tests needed to sort out the predictions of different models pertaining to the quark-gluon structure of hadrons are discussed, and given the resulting physics objectives, a few experimental options for excited baryon research at CFBAF are suggested
Observation of octet and decuplet hyperons in e+e- annihilation at 10 GeV centre-of-mass energy
Results on hyperon production are reported for data accumulated at 10 GeV centre-of-mass energy with the ARGUS detector. Signals for both the octet states Λ, Σ0 and Ξ- and the decuplet states Σ±(1385), Ξ0(1530) and Ω- are observed (references to a specific state are to be interpreted as also implying the charge conjugate state), some for the first time in e+e- annihilation. Baryon rates from Υdir (1S) decays are enhanced by a factor of about 3 over the continuum. (orig.)
Resonant Production of Color Octet Electron at the Lhec
Sahin, M; Turkoz, S
2010-01-01
In composite models with colored preons leptogluons (l_(8)) has a same status with leptoquarks, excited leptons and quarks etc. We analyze resonant production of color octet electron (e_(8)) at QCD Explorer stage of the Large Hadron electron Collider (LHeC). It is shown that the e_(8) discovery at the LHeC will simultaneously determine the compositeness scale.
Extended-soft-core Baryon-Baryon Model ESC08 I. Nucleon-Nucleon Scattering
Nagels, M M; Yamamoto, Y
2014-01-01
The Nijmegen extended-sft-core ESC08c model for the baryon-baryon (BB) interactions of the SU(3) flavor-octet of baryons ($N, \\Lambda, \\Sigma$, and $\\Xi$) is presented. In this first of a series of papers, the NN results are reported in detail. In the spirit of the Yukawa-approach to the nuclear force problem, the interactions are studied from the meson-exchange picture viewpoint, using generalized soft-core Yukawa-functions. These interactions are supplemented with (i) multiple-gluon-exchange, and (ii) structural effects due to the quark-core of the baryons. The extended-soft-core (ESC) meson-exchange interactions consist of local- and non-local-potentials due to ((i) One-boson-exchanges (OBE, which are the members of nonets of pseudoscalar , vector, scalar, and axial-vector mesons, (ii) diffractive (i.e. multiple-gluon) exchanges, (iii) two pseudoscalar exchange (PS-PS), and (iv) meson-pair-exchange (MPE). The OBE- and MPE-vertices are regulated by gaussian form factors producing potentials with a soft beha...
Staggered heavy baryon chiral perturbation theory
Bailey, Jon A.
2008-03-01
Although taste violations significantly affect the results of staggered calculations of pseudoscalar and heavy-light mesonic quantities, those entering staggered calculations of baryonic quantities have not been quantified. Here I develop staggered chiral perturbation theory in the light-quark baryon sector by mapping the Symanzik action into heavy baryon chiral perturbation theory. For 2+1 dynamical quark flavors, the masses of flavor-symmetric nucleons are calculated to third order in partially quenched and fully dynamical staggered chiral perturbation theory. To this order the expansion includes the leading chiral logarithms, which come from loops with virtual decuplet-like states, as well as terms of O(mπ3), which come from loops with virtual octet-like states. Taste violations enter through the meson propagators in loops and tree-level terms of O(a2). The pattern of taste symmetry breaking and the resulting degeneracies and mixings are discussed in detail. The resulting chiral forms are appropriate to lattice results obtained with operators already in use and could be used to study the restoration of taste symmetry in the continuum limit. I assume that the fourth root of the fermion determinant can be incorporated in staggered chiral perturbation theory using the replica method.
Kaplunovsky, Vadim; Sonnenschein, Jacob
2012-01-01
In the large N limit cold dense nuclear matter must be in a lattice phase. This applies also to holographic models of hadron physics. In a class of such models, like the generalized Sakai-Sugimoto model, baryons take the form of instantons of the effective flavor gauge theory that resides on probe flavor branes. In this paper we study the phase structure of baryonic crystals by analyzing discrete periodic configurations of such instantons. We find that instanton configurations exhibit a series of "popcorn" transitions upon increasing the density. Through these transitions normal (3D) lattices expand into the transverse dimension, eventually becoming a higher dimensional (4D) multi-layer lattice at large densities. We consider 3D lattices of zero size instantons as well as 1D periodic chains of finite size instantons, which serve as toy models of the full holographic systems. In particular, for the finite-size case we determine solutions of the corresponding ADHM equations for both a straight chain and for a 2...
On light baryons and their excitations
Eichmann, Gernot; Sanchis-Alepuz, Helios
2016-01-01
We study ground states and excitations of light octet and decuplet baryons within the framework of Dyson-Schwinger and Faddeev equations. We improve upon similar approaches by explicitly taking into account the momentum-dependent dynamics of the quark-gluon interaction that leads to dynamical chiral symmetry breaking. We perform calculations in both the three-body Faddeev framework and the quark-diquark approximation in order to assess the impact of the latter on the spectrum. Our results indicate that both approaches agree well with each other. The resulting spectra furthermore agree one-to-one with experiment, provided well-known deficiencies of the rainbow-ladder approximation are compensated for. We also discuss the mass evolution of the Roper and the excited Delta with varying pion mass and analyse the internal structure in terms of their partial wave decompositions.
Quark Spin and Orbital Angular Momentum in the Baryon
Song, X.
1999-01-01
The spin and orbital angular momentum carried by different quark flavors in the nucleon are calculated in the SU(3) chiral quark model with symmetry-breaking. The model is extended to all octet and decuplet baryons. In this model, the reduction of the quark spin, due to the spin dilution in the chiral splitting processes, is transferred into the orbital motion of quarks and antiquarks. The orbital angular momentum for each quark flavor in the proton as function of the partition factor $\\kappa...
Kaplunovsky, Vadim; Melnikov, Dmitry; Sonnenschein, Jacob
2012-11-01
In the large N c limit cold dense nuclear matter must be in a lattice phase. This applies also to holographic models of hadron physics. In a class of such models, like the generalized Sakai-Sugimoto model, baryons take the form of instantons of the effective flavor gauge theory that resides on probe flavor branes. In this paper we study the phase structure of baryonic crystals by analyzing discrete periodic configurations of such instantons. We find that instanton configurations exhibit a series of "popcorn" transitions upon increasing the density. Through these transitions normal (3D) lattices expand into the transverse dimension, eventually becoming a higher dimensional (4D) multi-layer lattice at large densities. We consider 3D lattices of zero size instantons as well as 1D periodic chains of finite size instantons, which serve as toy models of the full holographic systems. In particular, for the finite-size case we determine solutions of the corresponding ADHM equations for both a straight chain and for a 2D zigzag configuration where instantons pop up into the holographic dimension. At low density the system takes the form of an "abelian anti- ferromagnetic" straight periodic chain. Above a critical density there is a second order phase transition into a zigzag structure. An even higher density yields a rich phase space characterized by the formation of multi-layer zigzag structures. The finite size of the lattices in the transverse dimension is a signal of an emerging Fermi sea of quarks. We thus propose that the popcorn transitions indicate the onset of the "quarkyonic" phase of the cold dense nuclear matter.
Isospin splittings of meson and baryon masses from three-flavor lattice QCD+QED
Lattice QCD simulations are now reaching a precision where isospin breaking effects become important. Previously, we have developed a program to systematically investigate the pattern of flavor symmetry beaking within QCD and successfully applied it to meson and baryon masses involving up, down and strange quarks. In this Letter we extend the calculations to QCD+QED and present our first results on isospin splittings in the pseudoscalar meson and baryon octets. In particular, we obtain Mπ+ - Mπ0=4.60(20) MeV and Mn-Mp=1.35(18) MeV.
D-wave baryon resonances with charm from coupled-channel dynamics
Hofmann, J
2006-01-01
Identifying the zero-range exchange of vector mesons as the driving force for the s-wave scattering of pseudo-scalar mesons off the baryon ground states, the spectrum of ${3/2}^-$ molecules is computed. We predict a strongly bound 15-plet of $C=-1$ states. A narrow crypto-exotic octet of charm-zero states is foreseen. In the $C=+1$ sector a sextet of narrow resonances is formed due to the interaction of D mesons with the baryon decuplet. A strongly bound triplet of double-charm states is a consequence of coupled-channel dynamics driven by the D mesons.
On finite volume effects in the chiral extrapolation of baryon masses
Lutz, M F M; Kobdaj, C; Schwarz, K
2014-01-01
We perform an analysis of the QCD lattice data on the baryon octet and decuplet masses based on the relativistic chiral Lagrangian. The baryon self energies are computed in a finite volume at next-to-next-to-next-to leading order (N^3LO), where the dependence on the physical meson and baryon masses is kept. The number of free parameters is reduced significantly down to 12 by relying on large-N_c sum rules. Altogether we describe accurately more than 220 data points from six different lattice groups, BMW, PACS-CS, HSC, LHPC, QCDSF-UKQCD and NPLQCD. Precise values for all counter terms relevant at N^3LO are predicted. In particular we extract a pion-nucleon sigma term of (39 +- 1) MeV and a strangeness sigma term of the nucleon of sigma_{sN} simeq (4 +- 1) MeV. The flavour SU(3) chiral limit of the baryon octet and decuplet masses is determined with ( 802 +- 4 ) MeV and (1103 +- 6) MeV. Detailed predictions for the baryon masses as currently evaluated by the ETM lattice QCD group are made.
The soft function for color octet production at threshold
Czakon, M.; Fiedler, P.
2014-01-01
We evaluate the next-to-next-to-leading order soft function for the production of a massive color octet state at rest in the collision of two massless colored partons in either the fundamental or the adjoint representation. The main application of our result is the determination of the threshold expansion of the heavy-quark pair-production cross sections in the quark annihilation and gluon fusion channels. We discuss the factorization necessary for this purpose and explain the relationship be...
Flavor dependence of baryon melting temperature in effective models of QCD
Torres-Rincon, Juan M; Aichelin, Joerg
2015-01-01
We apply the three-flavor (Polyakov-)Nambu-Jona-Lasinio model to generate baryons as quark-diquark bound states using many-body techniques at finite temperature. All the baryonic states belonging to the octet and decuplet flavor representations are generated in the isospin-symmetric case. For each state we extract the melting temperature at which the baryon may decay into a quark-diquark pair. We seek for an evidence of the strangeness dependence of the baryon melting temperature as suggested by the statistical thermal models and supported by lattice-QCD results. A clear and robust signal for this claim is found, pointing to a flavor dependence of the hadronic deconfinement temperature.
Heavy Color-Octet Particles at the LHC
Chen, Chien-Yi; Han, Tao; Lee, Keith S M
2014-01-01
Many new-physics models, especially those with a color-triplet top-quark partner, contain a heavy color-octet state. The "naturalness" argument for a light Higgs boson requires that the color-octet state be not much heavier than a TeV, and thus it can be pair-produced with large cross sections at high-energy hadron colliders. It may decay preferentially to a top quark plus a top-partner, which subsequently decays to a top quark plus a color-singlet state. This singlet can serve as a WIMP dark-matter candidate. Such decay chains lead to a spectacular signal of four top quarks plus missing energy. We pursue a general categorization of the color-octet states and their decay products according to their spin and gauge quantum numbers. We review the current bounds on the new states at the LHC and study the expected discovery reach at the 8-TeV and 14-TeV runs. We also present the production rates at a future 100-TeV hadron collider, where the cross sections will be many orders of magnitude greater than at the 14-Te...
Calculation of the decay width of decuplet baryons
Alexandrou, Constantia; Petschlies, Marcus; Pochinsky, Andrew V; Syritsyn, Sergey S
2015-01-01
We calculate the coupling constant and decay width of the decuplet to octet baryon transitions in lattice QCD using the transfer matrix method. The transition amplitude is related to the coupling constant and via the Fermi's Golden Rule to the decay width. The method is applicable for near-degeneracy of the energy levels of initial and final states and, when this condition is fulfilled, yields a good estimate of the decay width. We present results using a hybrid action with domain wall valence quarks on a staggered sea with $350$ MeV pion mass as well as for a domain wall fermion action with $180$ MeV pion mass. We find $\\Gamma\\left( \\Delta \\to \\pi\\,N \\right) = 119\\,( 8)\\,( 8)$ MeV for the transition of Delta to pion-nucleon within the unitary domain wall setup. We also report values for the decay widths of the $\\Sigma^*$ and $\\Xi*$ baryons.
Quark-Model Baryon-Baryon Interaction and its Applications to Hypernuclei
Fujiwara, Y; Suzuki, Y; Kohno, M; Miyagawa, K
2004-01-01
The quark-model baryon-baryon interaction fss2, proposed by the Kyoto-Niigata group, is a unified model for the complete baryon octet (B_8=N, Lambda, Sigma and Xi), which is formulated in a framework of the (3q)-(3q) resonating-group method (RGM) using the spin-flavor SU_6 quark-model wave functions and effective meson-exchange potentials at the quark level. Model parameters are determined to reproduce properties of the nucleon-nucleon system and the low-energy cross section data for the hyperon-nucleon scattering. Due to the several improvements including the introduction of vector-meson exchange potentials, fss2 has achieved very accurate description of the NN and YN interactions, comparable to various one-boson exchange potentials. We review the essential features of fss2 and our previous model FSS, and their predictions to few-body systems in confrontation with the available experimental data. Some characteristic features of the B_8 B_8 interactions with the higher strangeness, S=-2, -3, -4, predicted by ...
Baryon-Baryon Interactions in the Flavor SU(3) Limit from Full QCD Simulations on the Lattice
Inoue, Takashi; Aoki, Sinya; Doi, Takumi; Hatsuda, Tetsuo; Ikeda, Yoichi; Murano, Keiko; Nemura, Hidekatsu; Sasaki, Kenji
2010-01-01
We investigate baryon-baryon (BB) interactions in the 3-flavor full QCD simulations with degenerate quark masses for all flavors. The BB potentials in the orbital S-wave are extracted from the Nambu-Bethe-Salpeter wave functions measured on the lattice. We observe strong flavor-spin dependences of the BB potentials at short distances. In particular, a strong repulsive core exists in the flavor-octet and spin-singlet channel (the 8_s representation), while an attractive core appears in the flavor singlet channel (the 1 representation). We discuss a relation of such flavor-spin dependence with the Pauli exclusion principle in the quark level. Possible existence of an H-dibaryon resonance above the Lambda-Lambda threshold is also discussed.
Baryonic and Non-Baryonic Dark Matter
Carr, Bernard
2000-01-01
Cosmological nucleosynthesis calculations imply that there should be both non-baryonic and baryonic dark matter. Recent data suggest that some of the non-baryonic dark matter must be "hot" (i.e. massive neutrinos) and there may also be evidence for "cold" dark matter (i.e. WIMPs). If the baryonic dark matter resides in galactic halos, it is likely to be in the form of compact objects (i.e. MACHOs) and these would probably be the remnants of a first generation of pregalactic or protogalactic P...
Chiral perturbation theory analysis of baryon temperature mass shifts
Bedaque, P F
1995-01-01
We compute the finite temperature pole mass shifts of the octet and decuplet baryons using heavy baryon chiral perturbation theory and the 1/N_c expansion, where N_c is the number of QCD colors. We consider the temperatures of the order of the pion mass m_\\pi, and expand truncate the chiral and 1/N_c expansions assuming that m_\\pi \\sim 1/N_c. There are three scales in the problem: the temperature T, the pion mass m_\\pi, and the octet--decuplet mass difference. Therefore, the result is not simply a power series in T. We find that the nucleon and \\Delta temperature mass shifts are opposite in sign, and that their mass difference changes by 20% in the temperature range 90 MeV < T < 130 MeV, that is the range where the freeze out in relativistic heavy ion collisions is expected to occur. We argue that our results are insensitive to the neglect of 1/N_c- supressed effects; the main purpose of the 1/N_c expansion in this work is to justify our treatment of the decuplet states.
Evidence for non-analytic light quark mass dependence in the baryon spectrum
Walker-Loud, Andre
2011-01-01
Using precise lattice QCD computations of the baryon spectrum, we present the first direct evidence for the presence of contributions to the baryon masses which are non-analytic in the light quark masses; contributions which are often denoted "chiral logarithms". We isolate the poor convergence of SU(3) baryon chiral perturbation theory to the flavor-singlet mass combination. The flavor-octet baryon mass splittings, which are corrected by chiral logarithms at next to leading order in SU(3) chiral perturbation theory, yield baryon-pion axial coupling constants D, F, C and H consistent with QCD values; the first evidence of chiral logarithms in the baryon spectrum. The Gell-Mann--Okubo relation, a flavor-27 baryon mass splitting, which is dominated by chiral corrections from light quark masses, provides further evidence for the presence of non-analytic light quark mass dependence in the baryon spectrum; we simultaneously find the GMO relation to be inconsistent with the first few terms in a taylor expansion in ...
Faria da Veiga, Paulo A.; O'Carroll, Michael; Valencia Alvites, José C.
2016-03-01
Considering a 3 + 1 dimensional lattice quantum chromodynamics (QCD) model defined with the improved Wilson action, three flavors, and 4 × 4 Dirac spin matrices, in the strong coupling regime, we reanalyze the question of the existence of the eightfold way baryons and complete our previous work where the existence of isospin octet baryons was rigorously solved. Here, we show the existence of isospin decuplet baryons which are associated with isolated dispersion curves in the subspace of the underlying quantum mechanical Hilbert space with vectors constructed with an odd number of fermion and antifermion basic quark and antiquark fields. Moreover, smoothness properties for these curves are obtained. The present work deals with a case for which the traditional method to solve the implicit equation for the dispersion curves, based on the use of the analytic implicit function theorem, cannot be applied. We do not have only one but two solutions for each one-baryon decuplet sector with fixed spin third component. Instead, we apply the Weierstrass preparation theorem, which also provides a general method for the general degenerate case. This work is completed by analyzing a spectral representation for the two-baryon correlations and providing the leading behaviors of the field strength normalization and the mass of the spectral contributions with more than one-particle. These are needed results for a rigorous analysis of the two-baryon and meson-baryon particle spectra.
Fukushima, Kenji
2014-01-01
We summarize recent developments in identifying the ground state of dense baryonic matter and beyond. The topics include deconfinement from baryonic matter to quark matter, a diquark mixture, topological effect coupled with chirality and density, and inhomogeneous chiral condensates.
Low-lying baryon spectrum with two dynamical twisted mass fermions
Alexandrou, C. [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Computation-based Science and Technology Research Center, Cyprus Institute, Nicosia (Cyprus); Baron, R.; Guichon, P. [CEA-Saclay, IRFU/Service de Physique Nucleaire, Gif-sur-Yvette (France); Carbonell, J.; Drach, V. [UJF/CNRS/IN2P3, Grenoble (France). Lab. de Physique Subatomique et Cosmologie; Jansen, K. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Korzec, T. [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Pene, O. [Paris-11 Univ., 91 - Orsay (France). Lab. de Physique Theorique
2009-10-15
The masses of the low lying baryons are evaluated using two degenerate flavors of twisted mass sea quarks corresponding to pseudo scalar masses in the range of about 270 MeV to 500 MeV. The strange valence quark mass is tuned to reproduce the mass of the kaon in the physical limit. The tree-level Symanzik improved gauge action is employed. We use lattices of spatial size 2.1 fm and 2.7 fm at two values of the lattice spacing with r{sub 0}/a=5.22(2) and r{sub 0}/a=6.61(3). We check for both finite volume and cut-off effects on the baryon masses. We performed a detailed study of the chiral extrapolation of the octet and decuplet masses using SU(2) {chi}PT. The lattice spacings determined using the nucleon mass at the physical point are consistent with the values extracted using the pion decay constant. We examine the issue of isospin symmetry breaking for the octet and decuplet baryons and its dependence on the lattice spacing. We show that in the continuum limit isospin breaking is consistent with zero, as expected. The baryon masses that we find after taking the continuum limit and extrapolating to the physical limit are in good agreement with experiment. (orig.)
The baryon vector current in the combined chiral and 1/Nc expansions
Flores-Mendieta, Ruben; Goity, Jose L [JLAB
2014-12-01
The baryon vector current is computed at one-loop order in large-Nc baryon chiral perturbation theory, where Nc is the number of colors. Loop graphs with octet and decuplet intermediate states are systematically incorporated into the analysis and the effects of the decuplet-octet mass difference and SU(3) flavor symmetry breaking are accounted for. There are large-Nc cancellations between different one-loop graphs as a consequence of the large-Nc spin-flavor symmetry of QCD baryons. The results are compared against the available experimental data through several fits in order to extract information about the unknown parameters. The large-Nc baryon chiral perturbation theory predictions are in very good agreement both with the expectations from the 1/Nc expansion and with the experimental data. The effect of SU(3) flavor symmetry breaking for the |Delta S|=1 vector current form factors f1(0) results in a reduction by a few percent with respect to the corresponding SU(3) symmetric values.
Low-lying baryon spectrum with two dynamical twisted mass fermions
The masses of the low lying baryons are evaluated using two degenerate flavors of twisted mass sea quarks corresponding to pseudo scalar masses in the range of about 270 MeV to 500 MeV. The strange valence quark mass is tuned to reproduce the mass of the kaon in the physical limit. The tree-level Symanzik improved gauge action is employed. We use lattices of spatial size 2.1 fm and 2.7 fm at two values of the lattice spacing with r0/a=5.22(2) and r0/a=6.61(3). We check for both finite volume and cut-off effects on the baryon masses. We performed a detailed study of the chiral extrapolation of the octet and decuplet masses using SU(2) χPT. The lattice spacings determined using the nucleon mass at the physical point are consistent with the values extracted using the pion decay constant. We examine the issue of isospin symmetry breaking for the octet and decuplet baryons and its dependence on the lattice spacing. We show that in the continuum limit isospin breaking is consistent with zero, as expected. The baryon masses that we find after taking the continuum limit and extrapolating to the physical limit are in good agreement with experiment. (orig.)
Yao, De-Liang; Siemens, D.; Bernard, V.; Epelbaum, E.; Gasparyan, A. M.; Gegelia, J.; Krebs, H.; Meißner, Ulf-G.
2016-05-01
We present the results of a third order calculation of the pion-nucleon scattering amplitude in a chiral effective field theory with pions, nucleons and delta resonances as explicit degrees of freedom. We work in a manifestly Lorentz invariant formulation of baryon chiral perturbation theory using dimensional regularization and the extended on-mass-shell renormalization scheme. In the delta resonance sector, the on mass-shell renormalization is realized as a complex-mass scheme. By fitting the low-energy constants of the effective Lagrangian to the S- and P -partial waves a satisfactory description of the phase shifts from the analysis of the Roy-Steiner equations is obtained. We predict the phase shifts for the D and F waves and compare them with the results of the analysis of the George Washington University group. The threshold parameters are calculated both in the delta-less and delta-full cases. Based on the determined low-energy constants, we discuss the pion-nucleon sigma term. Additionally, in order to determine the strangeness content of the nucleon, we calculate the octet baryon masses in the presence of decuplet resonances up to next-to-next-to-leading order in SU(3) baryon chiral perturbation theory. The octet baryon sigma terms are predicted as a byproduct of this calculation.
Relativistic chiral SU(3) symmetry, large Nc sum rules and meson-baryon scattering
The relativistic chiral SU(3) Lagrangian is used to describe kaon-nucleon scattering imposing constraints from the pion-nucleon sector and the axial-vector coupling constants of the baryon octet states. We solve the covariant coupled-channel Bethe-Salpeter equation with the interaction kernel truncated at chiral order Q3 where we include only those terms which are leading in the large Nc limit of QCD. The baryon decuplet states are an important explicit ingredient in our scheme, because together with the baryon octet states they form the large Nc baryon ground states of QCD. Part of our technical developments is a minimal chiral subtraction scheme within dimensional regularization, which leads to a manifest realization of the covariant chiral counting rules. All SU(3) symmetry-breaking effects are well controlled by the combined chiral and large Nc expansion, but still found to play a crucial role in understanding the empirical data. We achieve an excellent description of the data set typically up to laboratory momenta of plab ≅ 500 MeV. (orig.)
The soft function for color octet production at threshold
Czakon, M
2014-01-01
We evaluate the next-to-next-to-leading order soft function for the production of a massive color octet state at rest in the collision of two massless colored partons in either the fundamental or the adjoint representation. The main application of our result is the determination of the threshold expansion of the heavy-quark pair-production cross sections in the quark annihilation and gluon fusion channels. We discuss the factorization necessary for this purpose and explain the relationship between hard functions and virtual amplitudes.
$\\Upsilon$ decay into charmonium and the color octet mechanism
Trottier, Howard D.
1993-01-01
A factorization theorem for $P$-wave quarkonium production, recently derived by Bodwin, Braaten, Yuan and Lepage, is applied to $\\Upsilon \\to \\chi_{cJ} + X$, where $\\chi_{cJ}$ labels the ${}^3 P_J$ charmonium states. The widths for $\\chi_{cJ}$ production through color-singlet $P$-wave and color-octet $S$-wave $c \\bar c$ subprocesses are computed each to leading order in $\\alpha_s$. Experimental data on $\\Upsilon \\to J / \\psi + X$ is used to obtain an upper bound on a nonperturbative parameter...
Chemical Principles Revisited: The "6N+2 Rule" for Writing Lewis Octet Structures.
Zandler, Melvin E.; Talaty, Erach R.
1984-01-01
Provides a set of instructions for writing Lewis octet structures which incorporates a simple rule called the "6N+2 Rule." Discusses the importance of these structures in elementary chemistry, biochemistry, and organic chemistry courses. Also discusses non-octet structures and how they are characterized. (JM)
The calculation of the quark distribution amplitudes of decuplet baryons by means of QCD sum rules
Using the QCD sum rule technique, we derive the quark distribution amplitudes of the decuplet memebers Δ(1232), Σ*(1385), Ξ*(1530) and Ω(1672). Generalizing the treatment of the Bethe-Salpeter amplitude, we can distinguish spin- and orbital- angular momentum parts of the quark distributions and establish separate sum rules for the contributions. Projecting out the angular momentum 1/2 contributions, we obtain sum rules which are saturated by the lowest resonance in the given iso spin channel, thus resolving deficiencies of the standard approach. We find that for helicity 1/2 the spin part of the quark distributions is asymmetric. Also the orbital angular momentum contributions are extremely asymmetric and tend to decrease the asymmetry of the spin part. As a result of SU(3) symmetry breaking, configuration mixing occurs and the decuplet baryons Σ* and Ξ* receive octet contributions. The antisymmetric part of these octet contributions is calculated. (orig.)
Raduta, Ad R; Oertel, M
2014-01-01
The phase diagram of dense baryonic matter is investigated in the non-relativistic mean-field framework including the full baryonic octet. It is shown that, depending on the thermodynamic conditions, up to three strangeness-driven phase transitions may occur, such that a huge fraction of the total baryonic density domain corresponds to phase coexistence. The phase transitions are associated to the onset of the different hyperonic species or hyperonic families. We demonstrate that, due to a moderate component of the order parameter along the direction of charge density, phase coexistence persists if the Coulomb coupling to the electrons is accounted for. This makes the phase transition potentially relevant for neutron star and supernova evolution. The sensitivity of the results on the hyperonic coupling constants is explored, both for purely phenomenological energy functionals and for functionals adjusted to microscopic BHF calculations. We show that the presence of a phase transition is compatible both with t...
Quark Molecular Model of the S=0 Strange Pentaquark (u-sbar)-(uds) Baryon Spectrum
Williams, R A; Williams, Robert A.; Gueye, Paul
2003-01-01
We present a non-relativistic quark molecular model (QMM) of the strange crypto-exotic pentaquark baryon spectrum motivated by the recent data showing narrow, resonance enhancements in electromagnetic and hadronic production of kaons. Our model assumes color octet bonded quark molecular clusters forming exotic color singlet pentaquark baryons. We develop explicit molecular pentaquark wavefunctions that exhibit color interchange and cluster fermion antisymmetry. Our color electro-dynamics (CED) inspired Hamiltonian, which includes confinement, one gluon exchange and color magnetic interactions, is a natural generalization of the Isgur and Karl quark model Hamiltonian that reproduces the conventional meson (q-qbar) and baryon (qqq) spectrumWe introduce the idea of Color Magnetic Confinement (CMC) which is employed to restrict the physical pentaquark spectrum and constrain the fundamental constants (color gyromagnetic ratios) of the QMM-CED Hamiltonian. Comparing our QMM spectrum predictions with the recent expe...
On the consistency of recent QCD lattice data of the baryon ground-state masses
Lutz, M F M
2012-01-01
In our recent analysis of lattice data of the BMW, LHPC and PACS-CS groups we determined a parameter set of the chiral Lagrangian that allows a simultaneous description of the baryon octet and decuplet masses as measured by those lattice groups. The results on the baryon spectrum of the HSC group were recovered accurately without their inclusion into our 6 parameter fit. We show that the same parameter set provides an accurate reproduction of the recent results of the QCDSF-UKQCD group probing the baryon masses at quite different quark masses. This shows a remarkable consistency amongst the different lattice simulations. With even more accurate lattice data in the near future it will become feasible to determine all low-energy parameters relevant at N$^3$LO.
Experiments on strangeness production in nucleus-nucleus collisions at SIS energies address fundamental aspects of modern nuclear physics: the determination of the nuclear equation-of-state at high baryon densities and the properties of hadrons in dense nuclear matter. Experimental data and theoretical results will be reviewed. Future experiments at the FAIR accelerator aim at the exploration of the QCD phase diagram at highest baryon densities. The proposal for the Compressed Baryonic Matter (CBM) experiment will be presented. (author)
Exact formula of the spectrum of the pseudoscalar octet
R. Ling
2015-01-01
Full Text Available Non-perturbative proof is presented of a generalized version of Goldstone theorem, where the Lagrangian conserves an approximate SU(3 chiral symmetry, that both quark masses and electromagnetism make contributions to the masses of spinless particles of pseudoscalar octet. We show that apart from what comes in the form of some projections of a two-body Bethe–Salpeter amplitude for which the photon lines like the gluon ones are all internal in the case of neutral pseudo-Goldstone bosons, the charged pseudoscalar mesons receive additional contributions that may be expressed in terms of the axial–vectorial projection of a three-body Bethe–Salpeter amplitude with an extra external photon line.
Exact formula of the spectrum of the pseudoscalar octet
Ling, R., E-mail: raimund.ling@gmail.com [Department of Physics, Nanjing University, Nanjing 210093 (China); Li, B.L.; Ping, J.L. [School of Physics and Technology, Nanjing Normal University, Nanjing 210046 (China)
2015-01-05
Non-perturbative proof is presented of a generalized version of Goldstone theorem, where the Lagrangian conserves an approximate SU(3) chiral symmetry, that both quark masses and electromagnetism make contributions to the masses of spinless particles of pseudoscalar octet. We show that apart from what comes in the form of some projections of a two-body Bethe–Salpeter amplitude for which the photon lines like the gluon ones are all internal in the case of neutral pseudo-Goldstone bosons, the charged pseudoscalar mesons receive additional contributions that may be expressed in terms of the axial–vectorial projection of a three-body Bethe–Salpeter amplitude with an extra external photon line.
Two Higgs doublet models augmented by a scalar color octet
Cheng, Li
2016-01-01
The LHC is now studying in detail the couplings of the Higgs boson in order to determine if there is new physics. Many recent studies have examined the available fits to Higgs couplings from the perspective of constraining two Higgs doublet models (2HDM). In this paper we extend those studies to include constraints on the one loop couplings of the Higgs to gluons and photons. These couplings are particularly sensitive to the existence of new colored particles that are hard to detect otherwise and we use them to constrain a 2HDM augmented with a color-octet scalar, a possibility motivated by minimal flavor violation. We first study theoretical constraints on this model and then compare them with LHC measurements.
Exact formula of the spectrum of the pseudoscalar octet
Non-perturbative proof is presented of a generalized version of Goldstone theorem, where the Lagrangian conserves an approximate SU(3) chiral symmetry, that both quark masses and electromagnetism make contributions to the masses of spinless particles of pseudoscalar octet. We show that apart from what comes in the form of some projections of a two-body Bethe–Salpeter amplitude for which the photon lines like the gluon ones are all internal in the case of neutral pseudo-Goldstone bosons, the charged pseudoscalar mesons receive additional contributions that may be expressed in terms of the axial–vectorial projection of a three-body Bethe–Salpeter amplitude with an extra external photon line
The low-lying baryon spectrum with two dynamical twisted mass fermions
Alexandrou, C; Carbonell, J; Drach, V; Guichon, P; Jansen, K; Korzec, T; Pène, O
2009-01-01
The masses of the low lying baryons are evaluated using two degenerate flavors of twisted mass sea quarks corresponding to pseudo scalar masses in the range of about 270-500 MeV. The strange valence quark mass is tuned to reproduce the mass of the kaon in the physical limit. The tree-level Symanzik improved gauge action is employed. We use lattices of spatial size 2.1 fm and 2.7 fm at two values of the lattice spacing with $r_0/a=5.22(2)$ and $r_0/a=6.61(3)$. We check for both finite volume and cut-off effects on the baryon masses. We performed a detailed study of the chiral extrapolation of the octet and decuplet masses using SU(2) $\\chi$PT. The lattice spacings determined using the nucleon mass at the physical point are consistent with the values extracted using the pion decay constant. We examine the issue of isospin symmetry breaking for the octet and decuplet baryons and its dependence on the lattice spacing. We show that in the continuum limit isospin breaking is consistent with zero, as expected. The b...
Quark-model baryon-baryon interaction and its applications to hypernuclei
The quark-model baryon-baryon interaction fss2, proposed by the Kyoto-Niigata group, is a unified model for the complete baryon octet (B8=N, Λ, Σ and Ξ), which is formulated in a framework of the (3q)-(3q) resonating-group method (RGM) using the spin-flavor SU6 quark-model was functions and effective meson-exchange potentials at the quark level. Model parameters are determined to reproduce properties of the nucleon-nucleon system and the low-energy cross section data for the hyperon-nucleon scattering. Due to the several improvements including the introduction of vector-meson exchange potentials, fss2 has achieved very accurate description of the NN and YN interactions, comparable to various one-boson exchange potentials. We review the essential features of fss2 and our previous model FSS, and their predictions to few-body systems in confrontation with the available experimental data. Some characteristic features of the B8B8 interactions with the higher strangeness, S = -2, -3, -4, predicted by fss2 are discussed. These quark-model interactions are now applied to realistic calculations of few-body systems in a new three-cluster Faddeev formalism which uses two-cluster RGM kernels. As for the few-body systems, we discuss the three-nucleon bound states, the ΛNN-ΣNN system for the hypertriton, the ααΛ system for Λ9Be, and the ΛΛα system for ΛΛ6He. (author)
Study of ψ(3770) decaying to baryon anti-baryon pairs
Xia, Li-Gang
2016-05-01
To study the decays of ψ (3770) going to baryon anti-baryon pairs (B B bar), all available experiments of measuring the cross sections of e+e- → B B bar at center-of-mass energy ranging from 3.0 GeV to 3.9 GeV are combined. To relate the baryon octets, a model based on the SU(3) flavor symmetry is used and the SU(3) breaking effects are also considered. Assuming the electric and magnetic form factors are equal (|GE | = |GM |), a global fit including the interference between the QED process and the resonant process is performed. The branching fraction of ψ (3770) → B B bar is determined to be (2.4 ± 0.8 ± 0.3) ×10-5, (1.7 ± 0.6 ± 0.1) ×10-5, (4.5 ± 0.9 ± 0.1) ×10-5, (4.5 ± 0.9 ± 0.1) ×10-5, (2.0 ± 0.7 ± 0.1) ×10-5, and (2.0 ± 0.7 ± 0.1) ×10-5 for B = p , Λ ,Σ+ ,Σ0 ,Ξ- and Ξ0, respectively, where the first uncertainty is from the global fit and the second uncertainty is the systematic uncertainty due to the assumption |GE | = |GM |. They are at least one order of magnitude larger than a simple scaling of the branching fraction of J / ψ / ψ (3686) → B B bar .
Study of ψ(3770 decaying to baryon anti-baryon pairs
Li-Gang Xia
2016-05-01
Full Text Available To study the decays of ψ(3770 going to baryon anti-baryon pairs (BB¯, all available experiments of measuring the cross sections of e+e−→BB¯ at center-of-mass energy ranging from 3.0 GeV to 3.9 GeV are combined. To relate the baryon octets, a model based on the SU(3 flavor symmetry is used and the SU(3 breaking effects are also considered. Assuming the electric and magnetic form factors are equal (|GE|=|GM|, a global fit including the interference between the QED process and the resonant process is performed. The branching fraction of ψ(3770→BB¯ is determined to be (2.4±0.8±0.3×10−5, (1.7±0.6±0.1×10−5, (4.5±0.9±0.1×10−5, (4.5±0.9±0.1×10−5, (2.0±0.7±0.1×10−5, and (2.0±0.7±0.1×10−5 for B=p,Λ,Σ+,Σ0,Ξ− and Ξ0, respectively, where the first uncertainty is from the global fit and the second uncertainty is the systematic uncertainty due to the assumption |GE|=|GM|. They are at least one order of magnitude larger than a simple scaling of the branching fraction of J/ψ/ψ(3686→BB¯.
Bottom Baryon Decays to Pseudoscalar Meson and Pentaquark
Cheng, Hai-Yang
2015-01-01
Based on SU(3) flavor symmetry, we decompose the decay amplitudes of bottom baryon decays to a pseudoscalar meson and an octet or a decuplet pentaquark in terms of three invariant amplitudes $T_1$ and $T_{2,3}$ corresponding to external $W$-emission and internal $W$-emission diagrams, respectively. For antitriplet bottom baryons $\\Lambda_b^0,\\Xi_b^0$ and $\\Xi_b^-$, their decays to a decuplet pentaquark proceed only through the internal $W$-emission diagram. Assuming the dominance from the external $W$-emission amplitudes, we present an estimate of the decay rates relative to $\\Lambda_b^0\\to P_p^+K^-$, where $P_p^+$ is the hidden-charm pentaquark with the same light quark content as the proton. Hence, our numerical results will provide a very useful guideline to the experimental search for pentaquarks in bottom baryon decays. For example, $\\Xi_b^0\\to P_{\\Sigma^+}K^-$, $\\Xi_b^-\\to P_{\\Sigma^-}\\bar K^0$, $\\Omega_b^-\\to P_{\\Xi^-}\\bar K^0$ and $\\Omega_b^-\\to P_{\\Xi^0}K^-$ may have rates comparable to that of $\\Lam...
Spectroscopy of beautiful baryons
Caloi, R.; Gentile, S.; Mignani, R. (Rome Univ. (Italy). Ist. di Fisica)
1980-09-20
By assuming a non-relativistic quark model, an estimate of the masses of the low-lying (non-strange and non-charmed) beautiful baryons is given. Electromagnetic mass splittings of the same baryons are also discussed in some detail.
Three body calculations for studying the baryons are performed in a non-relativistic treatment with three quarks interacting via Bhaduri's potential. From the resulting wave functions, it is analysed under which conditions can a diquark structure occurs. Several photos showing quark distributions inside the baryons are presented and discussed in details
Υ Radiative Decays to Light Quark Jets and Color Octet Mechanism
GAO Ying-Jia; ZHANG Yu-Jie; CHAO Kuang-Ta
2006-01-01
We study radiative decays of Υ to light quark jets in nonrelativistic QCD by taking both the color singlet and color octet b(b) operators into consideration. The cut for quark jet energy and cut for the angle between two quarkjets are introduced. The sensitivity to the soft and collinear singularities in the loop integrals are greatly reduced by these cuts. With the jet energy cut of about 1 GeV, and the jet angle cut of about 36°, the branching ratio for Υ→γq(q)is found to be 8.2 × 10-4 from color singlet contributions. The color octet contributions could be much larger than that of color singlet, depending on the estimate of the color octet matrix elements. This process may provide a new test for the color octet mechanism in nonrelativistic QCD.
Associated J/ψ + γ Production Through Color-Octet Mechanism in P + Fe Collision
DUAN Chun-Gui; YAN Zhan-Yuan; HE Zhen-Min
2001-01-01
The contribution of color-octet heavy quarkonium production mechanism in P+ Fe → J/ψ + γ + X process is calculated and discussed. The results show that color-octet contributions are rather large and sometimes can exceed the color-singlct contributions. Using the structure function of Fe given by double Q2-rescaling model, the influence of nuclear effect on this process is also studied.``
G. Pilania; Gubernatis, J. E.; Lookman, T.
2015-01-01
The role of dynamical (or Born effective) charges in classification of octet AB-type binary compounds between four-fold (zincblende/wurtzite crystal structures) and six-fold (rocksalt crystal structure) coordinated systems is discussed. We show that the difference in the dynamical charges of the fourfold and sixfold coordinated structures, in combination with Harrison’s polarity, serves as an excellent feature to classify the coordination of 82 sp–bonded binary octet compounds. We use a suppo...
Low lying baryon spectrum with N{sub f}=2+1+1 dynamical twisted quarks
Drach, Vincent; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Carbonell, Jaume; Papinutto, Mauro [UJF, CNRS/IN2P3, INPG (France). Lab. de Physique Subatomique et de Cosmologie; Alexandrou, Constantia [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics
2010-12-15
We present first results on the octet and decuplet strange baryon spectrum with N{sub f}=2+1+1 twisted mass quarks. We use an Osterwalder Seiler valence strange quark with a mass tuned to the kaon and compare the results with those obtained in the unitary setup. This comparison allows to perform a first study of the lattice artefacts introduced by the mixed action approach. We investigate the effect of the strange and charm quarks in the sea by using two lattice spacings and comparing with preceding N{sub f}=2 twisted mass fermion calculations. (orig.)
Low lying baryon spectrum with Nf=2+1+1 dynamical twisted quarks
We present first results on the octet and decuplet strange baryon spectrum with Nf=2+1+1 twisted mass quarks. We use an Osterwalder Seiler valence strange quark with a mass tuned to the kaon and compare the results with those obtained in the unitary setup. This comparison allows to perform a first study of the lattice artefacts introduced by the mixed action approach. We investigate the effect of the strange and charm quarks in the sea by using two lattice spacings and comparing with preceding Nf=2 twisted mass fermion calculations. (orig.)
Dipion decays of heavy baryons
Compared with the charmed baryons, the bottom baryons are not known very well both experimentally and theoretically. In this paper, we investigate the dipion strong decays of the P-wave and D-wave excited bottom baryons in the framework of the QPC model. We also extend the same analysis to the charmed baryons
Torsten Leddig
2012-11-01
From inclusive measurements, it is known that about 7% of all mesons decay into final states with baryons. In these decays, some striking features become visible compared to mesonic decays. The largest branching fractions come with quite moderate multiplicities of 3–4 hadrons. We note that two-body decays to baryons are suppressed relative to three- and four-body decays. In most of these analyses, the invariant baryon–antibaryon mass shows an enhancement near the threshold. We propose a phenomenological interpretation of this quite common feature of hadronization to baryons.
Chiral dynamics of baryons in the perturbative chiral quark model
Pumsa-ard, K.
2006-07-01
In this work we develop and apply variants of a perturbative chiral quark model (PCQM) to the study of baryonic properties dominantly in the low-energy region. In a first step we consider a noncovariant form of the PCQM, where confinement is modelled by a static, effective potential and chiral corrections are treated to second order, in line with similar chiral quark models. We apply the PCQM to the study of the electromagnetic form factors of the baryon octet. We focus in particular on the low-energy observables such as the magnetic moments, the charge and magnetic radii. In addition, the electromagnetic N-delta transition is also studied in the framework of the PCQM. In the chiral loop calculations we consider a quark propagator, which is restricted to the quark ground state, or in hadronic language to nucleon and delta intermediate states, for simplicity. We furthermore include the low-lying excited states to the quark propagator. In particular, the charge radius of the neutron and the transverse helicity amplitudes of the N-delta transition are considerably improved by this additional effect. In a next step we develop a manifestly Lorentz covariant version of the PCQM, where in addition higher order chiral corrections are included. The full chiral quark Lagrangian is motivated by and in analogy to the one of Chiral Perturbation Theory (ChPT). This Lagrangian contains a set of low energy constants (LECs), which are parameters encoding short distance effects and heavy degrees of freedom. We evaluate the chiral Lagrangian to order O(p{sup 4}) and to one loop to generate the dressing of the bare quark operators by pseudoscalar mesons. In addition we include the vector meson degrees of freedom in our study. Projection of the dressed quark operators on the baryonic level serves to calculate the relevant matrix elements. In a first application of this scheme, we resort to a parameterization of the valence quark form factors in the electromagnetic sector. Constraints
Hidden charm octet tetraquarks from a diquark-antidiquark model
Zhu, Ruilin
2016-01-01
Four exotic charmonium-like states, i.e. $X(4140)$, $X(4274)$, $X(4500)$, and $X(4700)$, have been observed very recently by LHCb Collaboration in the decay process $B^+\\to J/\\psi \\phi K^+$ using the 3${\\rm fb}^{-1}$ data of $p\\bar p$ collision at $\\sqrt s= 7$ and $8$ TeV. In this paper, we investigate systematically the hidden charm tetraquark states. The hidden charm tetraquarks form an octet and a singlet representation according to flavor $SU(3)$ symmetry. Based on a diquark-antidiquark model, the hidden charm tetraquarks spectra are given. The previous XYZ exotic states altogether with the newly ones $X(4140)$, $X(4274)$, $X(4500)$, and $X(4700)$, can be well classified into certain representations. The spin-parities and masses of the XYZ are predicted, most of which are in agreement with the data. We particularly find that $Z_c(4430)$ can be treated as the first radial excitation of $Z_c(3900)$, while the $Y(1^{--})$ states can be obtained by the first orbital excitation of $X/Z$. Besides, we calculate ...
Photoproduction of hermaphrodite baryons
We show that photoexcitation of the lightest hermaphrodite baryons is strongly suppressed from proton targets but allowed from neutrons, a result that is reminiscent of a quark model selection rule due to Moorhouse. This is consistent with suggestions that the P11 (1710) is the lightest q3G baryon and eliminates the possibility of considerable mixing of q3G into the nucleon and delta's Fock space wavefunctions. (orig.)
Flavor structure of $\\Lambda$ baryons from lattice QCD - from strange to charm
Gubler, Philipp; Oka, Makoto
2016-01-01
$\\Lambda$ baryons of spin-parity $\\frac{1}{2}^{\\pm}$ with either a strange or charm valence quark are studied in full 2+1 flavor lattice QCD. Multiple $SU(3)$ singlet and octet operators are employed to generate the desired single baryon states on the lattice. Via the variational method, the couplings of these states to the different operators provide information about the flavor structure of the $\\Lambda$ baryons. We make use of the gauge configurations of the PACS-CS collaboration and chirally extrapolate the results for the masses and $SU(3)$ flavor components to the physical point. We furthermore gradually change the hopping parameter of the heaviest quark from strange to charm to study how the properties of the $\\Lambda$ baryons evolve as a function of the heavy quark mass. It is found that the baryon energy levels increase almost linearly with the quark mass. Meanwhile, the flavor structure of most of the states remains stable, with the exception of the lowest $\\frac{1}{2}^{-}$ state, which changes from...
Three-flavor chiral effective model with four baryonic multiplets within the mirror assignment
Olbrich, L; Giacosa, F
2016-01-01
We study three-flavor octet baryons by using the so-called extended Linear Sigma Model (eLSM). Within a quark-diquark picture, the requirement of a mirror assignment naturally leads to the consideration of four spin-$\\frac{1}{2}$ baryon multiplets. A reduction of the Lagrangian to the two-flavor case leaves four doublets of nucleonic states which mix to form the experimentally observed states $N(939)$, $N(1440)$, $N(1535)$ and $N(1650)$. We determine the parameters of the nucleonic part of the Lagrangian from a fit to masses and decay properties of the aforementioned states. By tracing their masses when chiral symmetry is restored, we conclude that the pairs $N(939)$, $N(1535)$ and $N(1440)$, $N(1650)$ form chiral partners.
Dark Matter and Color Octets Beyond the Standard Model
Krnjaic, Gordan Zdenko [Johns Hopkins Univ., Baltimore, MD (United States)
2012-07-01
Although the Standard Model (SM) of particles and interactions has survived forty years of experimental tests, it does not provide a complete description of nature. From cosmological and astrophysical observations, it is now clear that the majority of matter in the universe is not baryonic and interacts very weakly (if at all) via non-gravitational forces. The SM does not provide a dark matter candidate, so new particles must be introduced. Furthermore, recent Tevatron results suggest that SM predictions for benchmark collider observables are in tension with experimental observations. In this thesis, we will propose extensions to the SM that address each of these issues.
Dark matter, first definitely found in the large clusters of galaxies, is now known to be dominant mass in the outer parts of galaxies. All the mass definitely deduced could be made up of baryons, and this would fit well with the requirements of nucleosynthesis in a big bang of small ΩB. However, if inflation is the explanation of the expansion and large scale homogeneity of the universe and of baryon synthesis, and if the universe did not have an infinite extent at the big bang, then Ω should be minutely greater than unity. It is commonly hypothesized that most mass is composed of some unknown, non-baryonic form. This book first discusses the known forms, comets, planets, brown dwarfs, stars, gas, galaxies and Lyman α clouds in which baryons are known to exist. Limits on the amount of dark matter in baryonic form are discussed in the context of the big bang. Inhomogeneities of the right type alleviate the difficulties associated with ΩB = 1 cosmological nucleosynthesis
Color-octet Companions of a 750 GeV Heavy Pion
Bai, Yang; Berger, Joshua
2016-01-01
Color octet bosons are a universal prediction of models in which the 750 GeV diphoton resonance corresponds to a pion of a QCD-like composite sector. We show that the existing searches for dijet and photon plus jet resonances at the LHC constrain single productions of color octet states and can be translated into stringent limits on the 750 GeV diphoton rate. For a minimal 5 + 5bar model, the 750 GeV diphoton signal cross section at the 13 TeV LHC is constrained to be below around 5 fb. Future LHC searches for the photon plus jet resonances can establish evidence of a new color-octet state with 20/fb and validate a pion-like explanation for the 750 GeV resonance.
Indirect search for color octet electron at next generation linear colliders
Akay, A N; Sahin, M; Sultansoy, S
2010-01-01
In this study we investigated indirect manifestations of color octet electron at the next generation linear colliders: International Linear Collider (ILC) and Compact Linear Collider (CLIC). Namely, production of two gluons via color octet electron exchange is considered. Signal and background analysis have been performed taking into account initial state radiation and beamstrahlung. We show that color octet electron (e_(8)) manifestation will be seen upto M(e_(8))=1.75 TeV and 1.70 TeV at ILC and CLIC with sqrt(s)=0.5 TeV, respectively. CLIC with sqrt(s)=3 TeV will be sensitive upto M(e_(8)=6.88 TeV.
Quark cluster model of baryon-baryon interaction
The quark cluster model of the baryon-baryon interaction is reviewed. The emphasis is on the foundation of the approach and the main features of the model. The origins of the short-range repulsion in the nuclear force and other baryonic interactions are discussed. (author)
Supersymmetric Baryonic Branes
Gomis, J P; Simón, J; Townsend, P K; Gomis, Joaquim; Ramallo, Alfonso V.; Simon, Joan; Townsend, Paul K.
1999-01-01
We derive an energy bound for a `baryonic' D5-brane probe in the $adS_5\\times S^5$ background near the horizon of $N$ D3-branes. Configurations saturating the bound are shown to be 1/4 supersymmetric $S^5$-wrapped D5-branes with $N$ singularities at arbitrary positions. Previous results for $N$ coincident singularities are recovered as a special case. We derive a similar energy bound for a `baryonic' M5-brane probe in the background of $N$ M5-branes. Configurations saturating the bound are again 1/4 supersymmetric and, in the $adS_7\\times S^4$ near-horizon limit, provide a worldvolume realization of the `baryon string' vertex of the (2,0)-supersymmetric six-dimensional conformal field theory on coincident M5-branes. For the full M5-background we find a worldvolume realization of the Hannany-Witten effect in M-theory.
Measurements of inclusive Λ + anti Λ production for 1.0 less than or equal to p less than or equal to 10.0 GeV/c and p + anti p production for 0.4 less than or equal to p less than or equal to 2.0 GeV/c show significant baryon production in e+e- annihilation at E/sub cm/ = 29 GeV. Λ + anti Λ production represents 0.2 Λ's or anti Λ's per PEP event while the observed p + anti p production implies all baryon-antibaryon pair production is occurring at least as often as 0.6 per event, depending on the yet to be measured p + anti p production at high momentum. Comparisons are made with the first theoretical attempts to account for baryon production at these energies
Charmed Bottom Baryon Spectroscopy
Brown, Zachary S; Detmold, William; Meinel, Stefan; Orginos, Kostas
2014-11-01
The spectrum of doubly and triply heavy baryons remains experimentally unexplored to a large extent. Although the detection of such heavy particle states may lie beyond the reach of exper- iments for some time, it is interesting compute this spectrum from QCD and compare results between lattice calculations and continuum theoretical models. Several lattice calculations ex- ist for both doubly and triply charmed as well as doubly and triply bottom baryons. Here, we present preliminary results from the first lattice calculation of doubly and triply heavy baryons including both charm and bottom quarks. We use domain wall fermions for 2+1 flavors (up down and strange) of sea and valence quarks, a relativistic heavy quark action for the charm quarks, and non-relativistic QCD for the heavier bottom quarks. We present preliminary results for the ground state spectrum.
Baryon-baryon interactions in the SU6 quark model and their applications to light nuclear systems
Fujiwara, Y; Suzuki, Y
2006-01-01
Interactions between the octet-baryons (B8) in the spin-flavor SU6 quark model are investigated in a unified coupled-channels framework of the resonating-group method (RGM). The interaction Hamiltonian for quarks consists of the phenomenological confinement potential, the color Fermi-Breit interaction with explicit flavor-symmetry breaking (FSB), and effective-meson exchange potentials of scalar-, pseudoscalar- and vector-meson types. The model parameters are determined to reproduce the properties of the nucleon-nucleon (NN) system and the low-energy cross section data for the hyperon-nucleon (YN) interactions. The NN phase shifts and many observables for the NN and YN interactions are nicely reproduced. Properties of these B8 B8 interactions are analyzed through the G-matrix calculations. The B8 B8 interactions are then applied to some of few-baryon systems and light Lambda-hypernuclei in a three-cluster Faddeev formalism using two-cluster RGM kernels. An application to the three-nucleon system shows that th...
Photoproduction of hermaphrodite baryons
It is shown that photoexcitation of the lightest hermaphrodite baryons is strongly suppressed from proton targets but allowed from neutrons, a result that is reminiscent of a quark model selection rule due to Moorhouse (Phys. Rev. Lett.; 16:772 (1966)). This is consistent with suggestions that the P11(1710) is the lightest q3G baryon and eliminates the possibility that the Roper resonance is dominantly an hermaphrodite state. Magnetic moments do not constrain the possibility of considerable mixing of q3G into the nucleon and delta's Fock space wavefunctions. (author)
Using state of the art lattice techniques we investigate the static baryon potential. We employ the multi-hit procedure for the time links and a variational approach to determine the ground state with sufficient accuracy that, for distances up to ∼ 1.2 fm, we can distinguish the Y- and Δ- Ansaetze for the baryonic Wilson area law. Our analysis shows that the Δ-Ansatz is favoured. This result is also supported by the gauge-invariant nucleon wave function which we measure for the first time
Liu, Keh-Fei
2016-01-01
The relevance of chiral symmetry in baryons is highlighted in three examples in the nucleon spectroscopy and structure. The first one is the importance of chiral dynamics in understanding the Roper resonance. The second one is the role of chiral symmetry in the lattice calculation of $\\pi N \\sigma$ term and strangeness. The third one is the role of chiral $U(1)$ anomaly in the anomalous Ward identity in evaluating the quark spin and the quark orbital angular momentum. Finally, the chiral effective theory for baryons is discussed.
Electroproduction of light quark baryons
The status of electromagnetic excitation of light quark (u, d) baryon states is reviewed and confronted with results of calculations within the framework of microscopic models of the baryon structure and the photon-baryon coupling. Prospects for a qualitative improvement of our knowledge in this sector using photon and electron beams at the new, intermediate energy continuous wave electron machines are discussed
Electromagnetic properties of light and heavy baryons in the relativistic quark model
Nicmorus Marinescu, Diana
2007-06-14
One of the main challenges of nowadays low-energy physics remains the description of the internal structure of hadrons, strongly connected to the electromagnetic properties of matter. In this vein, the success of the relativistic quark model in the analysis of the hadron structure constitutes a solid motivation for the study carried out throughout this work. The relativistic quark model is extended to the investigation of static electromagnetic properties of both heavy and light baryons. The bare contributions to the magnetic moments of the single-, double- and triple-heavy baryons are calculated. Moreover, the relativistic quark model allows the study of the electromagnetic properties of the light baryon octet incorporating meson cloud contributions in a perturbative manner. The long disputed values of the multipole ratios E2/M1 and C2/M1 and the electromagnetic form factors of the N{yields}{delta}{gamma} transition are successfully reproduced. The relativistic quark model can be viewed as a quantum field theory approach based on a phenomenological Lagrangian coupling light and heavy baryons to their constituent quarks. In our approach the baryon is a composite object of three constituent quarks, at least in leading order. The effective interaction Lagrangian is written in terms of baryon and constituent quark fields. The effective action preserves Lorentz covariance and gauge invariance. The main ingredients of the model are already introduced at the level of the interaction Lagrangian: the three-quark baryon currents, the Gaussian distribution of the constituent quarks inside the baryon and the compositeness condition which sets an upper limit for the baryon-quark vertex. The S-matrix elements are expressed by a set of Feynman quark-diagrams. The model contains only few parameters, namely, the cut-off parameter of the Gaussian quark distribution and the free quark propagator, which are unambiguously determined from the best fit to the data. The heavy quark limit
Electromagnetic properties of light and heavy baryons in the relativistic quark model
One of the main challenges of nowadays low-energy physics remains the description of the internal structure of hadrons, strongly connected to the electromagnetic properties of matter. In this vein, the success of the relativistic quark model in the analysis of the hadron structure constitutes a solid motivation for the study carried out throughout this work. The relativistic quark model is extended to the investigation of static electromagnetic properties of both heavy and light baryons. The bare contributions to the magnetic moments of the single-, double- and triple-heavy baryons are calculated. Moreover, the relativistic quark model allows the study of the electromagnetic properties of the light baryon octet incorporating meson cloud contributions in a perturbative manner. The long disputed values of the multipole ratios E2/M1 and C2/M1 and the electromagnetic form factors of the N→Δγ transition are successfully reproduced. The relativistic quark model can be viewed as a quantum field theory approach based on a phenomenological Lagrangian coupling light and heavy baryons to their constituent quarks. In our approach the baryon is a composite object of three constituent quarks, at least in leading order. The effective interaction Lagrangian is written in terms of baryon and constituent quark fields. The effective action preserves Lorentz covariance and gauge invariance. The main ingredients of the model are already introduced at the level of the interaction Lagrangian: the three-quark baryon currents, the Gaussian distribution of the constituent quarks inside the baryon and the compositeness condition which sets an upper limit for the baryon-quark vertex. The S-matrix elements are expressed by a set of Feynman quark-diagrams. The model contains only few parameters, namely, the cut-off parameter of the Gaussian quark distribution and the free quark propagator, which are unambiguously determined from the best fit to the data. The heavy quark limit within this
Babu, K S; Al-Binni, U; Banerjee, S; Baxter, D V; Berezhiani, Z; Bergevin, M; Bhattacharya, S; Brice, S; Brock, R; Burgess, T W; Castellanos, L; Chattopadhyay, S; Chen, M-C; Church, E; Coppola, C E; Cowen, D F; Cowsik, R; Crabtree, J A; Davoudiasl, H; Dermisek, R; Dolgov, A; Dutta, B; Dvali, G; Ferguson, P; Perez, P Fileviez; Gabriel, T; Gal, A; Gallmeier, F; Ganezer, K S; Gogoladze, I; Golubeva, E S; Graves, V B; Greene, G; Handler, T; Hartfiel, B; Hawari, A; Heilbronn, L; Hill, J; Jaffe, D; Johnson, C; Jung, C K; Kamyshkov, Y; Kerbikov, B; Kopeliovich, B Z; Kopeliovich, V B; Korsch, W; Lachenmaier, T; Langacker, P; Liu, C-Y; Marciano, W J; Mocko, M; Mohapatra, R N; Mokhov, N; Muhrer, G; Mumm, P; Nath, P; Obayashi, Y; Okun, L; Pati, J C; Pattie, R W; Phillips, D G; Quigg, C; Raaf, J L; Raby, S; Ramberg, E; Ray, A; Roy, A; Ruggles, A; Sarkar, U; Saunders, A; Serebrov, A; Shafi, Q; Shimizu, H; Shiozawa, M; Shrock, R; Sikdar, A K; Snow, W M; Soha, A; Spanier, S; Stavenga, G C; Striganov, S; Svoboda, R; Tang, Z; Tavartkiladze, Z; Townsend, L; Tulin, S; Vainshtein, A; Van Kooten, R; Wagner, C E M; Wang, Z; Wehring, B; Wilson, R J; Wise, M; Yokoyama, M; Young, A R
2013-01-01
This report, prepared for the Community Planning Study - Snowmass 2013 - summarizes the theoretical motivations and the experimental efforts to search for baryon number violation, focussing on nucleon decay and neutron-antineutron oscillations. Present and future nucleon decay search experiments using large underground detectors, as well as planned neutron-antineutron oscillation search experiments with free neutron beams are highlighted.
By formal manipulation of the QCD functional integral we arrive at a relativistic low energy effective theory of non-local color singlet mesons and baryons, which at tree level sums up ladders of effective glue exchange between constituent quarks. (orig.)
Problems in baryon spectroscopy
Capstick, S. [Florida State Univ., Tallahassee, FL (United States)
1994-04-01
Current issues and problems in the physics of ground- and excited-state baryons are considered, and are classified into those which should be resolved by CEBAF in its present form, and those which may require CEBAF to undergo an energy upgrade to 8 GeV or more. Recent theoretical developments designed to address these problems are outlined.
Paolis, F.; Ingrosso, G.; Jetzer, Ph.; Roncadelli, M.
1997-01-01
Reasons supporting the idea that most of the dark matter in galaxies and clusters of galaxies is baryonic are discussed. Moreover, it is argued that most of the dark matter in galactic halos should be in the form of MACHOs and cold molecular clouds.
Photoproduction of charmed baryons
The results of a search for the photoproduction of charmed baryons in the broad-band neutral beam at Fermi National Accelerator Laboratory are reported. The lowest lying charmed baryon (Λ/sub c/+) is observed through its decay to p-anti K0. The cross section times branching ratio of γ + C → Λ/sub c/+ + X, γ + C → p + anti K0 is measured to be sigma B = 3 nanobarns/nucleon. The total error on this measurement is estimated to be -20% to +40%. The mass of the Λ/sub c/+ is found to be 2.284 +- 0.001 GeV/c2, in good agreement with the Mark II result from SPEAR. Upper limits (90% confidence level) are set on sigma B for the modes Λ0π, Λ0πππ, pKπ
Buccella, F.; Farrar, G.R.; Rutgers - the State Univ., New Brunswick, NJ; Pugliese, A.
1985-04-04
The MIT bag model is used to calculate masses of (R-)baryons, composed of three quarks and a gluino. If the gluino mass is small, the lightest of these, a flavor singlet, could be long-lived or even absolutely stable. The next lighest, the R-nucleons, probably have only weak decays, while all others are likely to decay strongly. This physical picture is not ruled out experimentally. (orig.).
Buccella, F.; Farrar, G.R.; Pugliese, A.
1985-04-04
The MIT bag model is used to calculate masses of (R-)baryons, composed of three quarks and a gluino. If the gluino mass is small, the lightest of these, a flavor singlet, could be long-lived or even absolutely stable. The next lighest, the R-nucleons, probably have only weak decays, while all others are likely to decay strongly. This physical picture is not ruled out experimentally.
The MIT bag model is used to calculate masses of (R-)baryons, composed of three quarks and a gluino. If the gluino mass is small, the lightest of these, a flavor singlet, could be long-lived or even absolutely stable. The next lighest, the R-nucleons, probably have only weak decays, while all others are likely to decay strongly. This physical picture is not ruled out experimentally. (orig.)
CP Violating Baryon Oscillations
McKeen, David; Nelson, Ann E.
2015-01-01
We analyze neutron-antineutron oscillation in detail, developing a Hamiltonian describing the system in the presence of electromagnetic fields. While magnetic fields can couple states of different spin, we show that, because of Fermi statistics, this coupling of different spin states does not involve baryon-number--changing transitions and, therefore, a two-state analysis ignoring spin is sufficient even in the presence of electromagnetic fields. We also enumerate the conditions necessary for...
Reconstructing baryon oscillations
Noh, Yookyung; White, Martin; Padmanabhan, Nikhil
2009-01-01
The baryon acoustic oscillation (BAO) method for constraining the expansion history is adversely affected by non-linear structure formation, which washes out the correlation function peak created at decoupling. To increase the constraining power of low z BAO experiments, it has been proposed that one use the observed distribution of galaxies to "reconstruct'' the acoustic peak. Recently Padmanabhan, White and Cohn provided an analytic formalism for understanding how reconstruction works withi...
Strangeness S = -3 and -4 baryon-baryon interactions in chiral EFT
I report on recent progress in the description of baryon-baryon systems within chiral effective field theory. In particular, I discuss results for the strangeness S = -3 to -4 baryon-baryon systems, obtained to leading order.
Baryon spectroscopy in lattice QCD
Derek B. Leinweber; Wolodymyr Melnitchouk; David Richards; Anthony G. Williams; James Zanotti
2004-04-01
We review recent developments in the study of excited baryon spectroscopy in lattice QCD. After introducing the basic methods used to extract masses from correlation functions, we discuss various interpolating fields and lattice actions commonly used in the literature. We present a survey of results of recent calculations of excited baryons in quenched QCD, and outline possible future directions in the study of baryon spectra.
Chiral dynamics and baryon resonances
Hyodo, Tetsuo
2010-01-01
The structure of baryon resonance in coupled-channel meson-baryon scattering is studied from the viewpoint of chiral dynamics. The meson-baryon scattering amplitude can be successfully described together with the properties of the resonance in the scattering, by implementing the unitarity condition for the amplitude whose low energy structure is constrained by chiral theorem. Recently, there have been a major progress in the study of the structure of the resonance in chiral dynamics. We revie...
Ding, Ran [Peking University, Center for High Energy Physics, Beijing (China); Han, Zhi-Long; Ma, Xiao-Dong [Nankai University, School of Physics, Tianjin (China); Liao, Yi [Peking University, Center for High Energy Physics, Beijing (China); Nankai University, School of Physics, Tianjin (China); Chinese Academy of Sciences, State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Beijing (China)
2016-04-15
We propose that the possible 750 GeV diphoton excess can be explained in the color-octet neutrino mass model extended with a scalar singlet Φ. The model generally contains N{sub s} species of color-octet, electroweak doublet scalars S and N{sub f} species of color-octet, electroweak triplet χ or singlet ρ fermions. While both scalars and fermions contribute to the production of Φ through gluon fusion, only the charged members induce the diphoton decay of Φ. The diphoton rate can be significantly enhanced due to interference between the scalar and fermion loops.We show that the diphoton cross section can be from 3 to 10 fb for O(TeV) color-octet particles while evading all current LHC limits. (orig.)
Ding, Ran; Liao, Yi; Ma, Xiao-Dong
2016-01-01
We propose that the possible 750 GeV diphoton excess can be explained in the color-octet neutrino mass model extended with a scalar singlet $\\Phi$. The model generally contains $N_s$ species of color-octet, electroweak doublet scalars $S$ and $N_f$ species of color-octet, electroweak triplet $\\chi$ or singlet $\\rho$ fermions. While both scalars and fermions contribute to the production of $\\Phi$ through gluon fusion, only the charged members induce the diphoton decay of $\\Phi$. The diphoton rate can be significantly enhanced due to interference between the scalar and fermion loops. We show that the diphoton cross section can be from 3 to 10 fb for O(TeV) color-octet particles while evading all current LHC limits.
We propose that the possible 750 GeV diphoton excess can be explained in the color-octet neutrino mass model extended with a scalar singlet Φ. The model generally contains Ns species of color-octet, electroweak doublet scalars S and Nf species of color-octet, electroweak triplet χ or singlet ρ fermions. While both scalars and fermions contribute to the production of Φ through gluon fusion, only the charged members induce the diphoton decay of Φ. The diphoton rate can be significantly enhanced due to interference between the scalar and fermion loops.We show that the diphoton cross section can be from 3 to 10 fb for O(TeV) color-octet particles while evading all current LHC limits. (orig.)
Composite scalars at the LHC: the Higgs, the Sextet and the Octet
Cacciapaglia, Giacomo; Cai, Haiying; Deandrea, Aldo; Flacke, Thomas; Lee, Seung J.; Parolini, Alberto
2015-11-01
We present a phenomenological theory of scalar particles that transform as a sextet and an octet of QCD interactions. These particles may arise as light bound states of a fundamental dynamics giving rise to a composite Higgs boson and partial compositeness for the top. As a concrete example, we discuss an explicit UV completion based on the SU(4)/Sp(4) coset, where QCD colour is carried by additional fundamental fermions charged under the confining gauge group. Top partners, as well as potentially even lighter coloured scalars, arise as bound states of the coloured fermions. We study production and detection at LHC Run I and II of the octet and sextet, setting lower limits on masses and couplings to Standard Model particles using existing 8 TeV analyses. We finally explore prospects for the ongoing 13 TeV Run II: we focus on final states with two same sign leptons, that have the potential to discriminate the sextet.
Composite scalars at the LHC: the Higgs, the Sextet and the Octet
Cacciapaglia, Giacomo; Deandrea, Aldo; Flacke, Thomas; Lee, Seung J; Parolini, Alberto
2015-01-01
We present a phenomenological theory of scalar particles that transform as a sextet and an octet of QCD interactions. These particles may arise as light bound states of a fundamental dynamics giving rise to a composite Higgs boson and partial compositeness for the top. As a concrete example, we discuss an explicit UV completion based on the SU(4)/Sp(4) coset, where QCD colour is carried by additional fundamental fermions charged under the confining gauge group. Top partners, as well as potentially even lighter coloured scalars, arise as bound states of the coloured fermions. We study production and detection at LHC Run I and II of the octet and sextet, setting lower limits on masses and couplings to Standard Model particles using existing 8 TeV analyses. We finally explore prospects for the ongoing 13 TeV Run II: we focus on final states with two same sign leptons, that have the potential to discriminate the sextet.
The Polyakov loop correlator at NNLO and singlet and octet correlators
Ghiglieri, Jacopo
2010-01-01
We present the complete next-to-next-to-leading-order calculation of the correlation function of two Polyakov loops for temperatures smaller than the inverse distance between the loops and larger than the Coulomb potential. We discuss the relationship of this correlator with the singlet and octet potentials which we obtain in an Effective Field Theory framework based on finite-temperature potential Non-Relativistic QCD, showing that the Polyakov loop correlator can be re-expressed, at the lea...
Phenomenological SU(6) breaking of baryon wave functions and the chromodynamic spin-spin force
A contradiction is found between two successful models of SU(6) breaking. A quark-model mixing scheme (56,0+) + (70,0+) for the baryon octet has been devised to explain the ratio F/sup e/n2(x)/F/sup e/p2(x) in the valence-quark region and explains naturally other departures from the usual SU(6) predictions. On the other hand, the gluon-exchange model of SU(6) breaking accounts satisfactorily for the hadron spectrum splittings. The spin-spin contribution from this chromodynamic force is indeed shown to generate a (56,0+) + (70,0+) mixing of the octet. However, it yields a wrong sign for the mixing angle, thus pointing to a contradiction between spin-spin forces of one-gluon-exchange type and the deep-inelastic structure functions in the valence-quark region. Other spin-spin potentials, giving the right sign for the mixing angle, are shown to be also in difficulty, because of the hyperfine structure of excited levels. Finally, a careful discussion is made of the subtle Σ-Λ effect in both approaches
Color-octet contributions to P-wave Bc meson hadroproduction
The contributions from the color-octet components vertical bar (cb)8(1S0)g> and vertical bar (cb)8(3S1)g> to the hBc or χBcJ (the P-wave Bc meson) hadroproduction are estimated in terms of the complete O(αs4) calculation. As necessary inputs in the estimate, we take the values of the octet matrix elements according to the nonrelativistic quantum chromodynamics scaling rules, and as a result, we have found that the contributions to the P-wave production may be the same in order of magnitude as those from the color-singlet ones, |(cb)1(1P1)> and |(cb)1(3PJ)> (J=1,2,3). Especially, our result indicates that the observation of the color-octet contributions to the P-wave production in the low transverse momentum region is not very far from the present experimental capability at Tevatron and LHC
Strange Baryon Electromagnetic Form Factors and SU(3) Flavor Symmetry Breaking
Lin, Huey-Wen; Orginos, Konstantinos
2009-01-01
We study the nucleon, Sigma and cascade octet baryon electromagnetic form factors and the effects of SU(3) flavor symmetry breaking from 2+1-flavor lattice calculations. We find that electric and magnetic radii are similar; the maximum discrepancy is about 10\\%. In the pion-mass region we explore, both the quark-component and full-baryon moments have small SU(3) symmetry breaking. We extrapolate the charge radii and the magnetic moments using three-flavor heavy-baryon chiral perturbation theory (HBXPT). The systematic errors due to chiral and continuum extrapolations remain significant, giving rise to charge radii for $p$ and $\\Sigma^-$ that are 3--4 standard deviations away from the known experimental ones. Within these systematics the predicted $\\Sigma^+$ and $\\Xi^-$ radii are 0.67(5) and 0.306(15)~fm$^2$ respectively. When the next-to-next-to-leading order of HBXPT is included, the extrapolated magnetic moments are less than 3 standard deviations away from PDG values, and the d
Nawa, K; Suganuma, H; Kojo, Toru; Nawa, Kanabu; Suganuma, Hideo
2006-01-01
We study the baryon in holographic QCD with $D4/D8/\\bar{D8}$ multi-$D$ brane system. In holographic QCD, the baryon appears as a topologically non-trivial chiral soliton in a four-dimensional effective theory of mesons. We call this topological soliton as Brane-induced Skyrmion. Some review of $D4/D8/\\bar{D8}$ holographic QCD is presented from the viewpoints of recent hadron physics and phenomenologies. Four-dimensional effective theory with pions and $\\rho$ mesons is uniquely derived from the non-abelian Dirac-Born-Infeld (DBI) action of $D8$ brane with $D4$ supergravity background, without small amplitude expansion of meson fields to discuss chiral solitons. For the hedgehog configuration of pion and $\\rho$-meson fields, we derive the energy functional and the Euler-Lagrange equation of Brane-induced Skyrmion from the meson effective action induced by holographic QCD. Performing the numerical calculation, we obtain the pion profile $F(r)$ and the $\\rho$-meson profile $G(r)$ of the Brane-induced Skyrmion, an...
Dynamically generated baryon resonances
Lutz, M F M
2005-01-01
Identifying a zero-range exchange of vector mesons as the driving force for the s-wave scattering of pseudo-scalar mesons off the baryon ground states, a rich spectrum of molecules is formed. We argue that chiral symmetry and large-$N_c$ considerations determine that part of the interaction which generates the spectrum. We suggest the existence of strongly bound crypto-exotic baryons, which contain a charm-anti-charm pair. Such states are narrow since they can decay only via OZI-violating processes. A narrow nucleon resonance is found at mass 3.52 GeV. It is a coupled-channel bound state of the $(\\eta_c N), (\\bar D \\Sigma_c)$ system, which decays dominantly into the $(\\eta' N)$ channel. Furthermore two isospin singlet hyperon states at mass 3.23 GeV and 3.58 GeV are observed as a consequence of coupled-channel interactions of the $(\\bar D_s \\Lambda_c), (\\bar D \\Xi_c)$ and $(\\eta_c \\Lambda),(\\bar D \\Xi_c')$ states. Most striking is the small width of about 1 MeV of the lower state. The upper state may be signi...
The Spectrum of the Baryon Masses in a Self-consistent SU(3) Quantum Skyrme Model
Jurciukonis, Darius; Regelskis, Vidas
2012-01-01
The semiclassical SU(3) Skyrme model is traditionally considered as describing a rigid quantum rotator with the profile function being fixed by the classical solution of the corresponding SU(2) Skyrme model. In contrast, we go beyond the classical profile function by quantizing the SU(3) Skyrme model canonically. The quantization of the model is performed in terms of the collective coordinate formalism and leads to the establishment of purely quantum corrections of the model. These new corrections are of fundamental importance. They are crucial in obtaining stable quantum solitons of the quantum SU(3) Skyrme model, thus making the model self-consistent and not dependent on the classical solution of the SU(2) case. We show that such a treatment of the model leads to a family of stable quantum solitons that describe the baryon octet and decuplet and reproduce the experimental values of their masses.
Baryon Production in the String Fragmentation Picture
Eden, Patrik; Gustafson, Gosta
1996-01-01
An improved version of the ``pop-corn'' model for baryon production in quark and gluon jets is presented. With a reduced number of parameters the model reproduces well both production rates for different baryon species and baryon momentum distributions. Predictions are presented for a set of baryon-antibaryon correlations.
Decay and spectra of baryons especially beauty baryons
Kalman, C. S.
1996-06-01
Masses and decays of the baryons are considered. The entire spectroscopy of baryons containing u,d,s,c and b quarks is calculated using the five quark masses and only four additional parameters describing the potential between the baryons. This potential is taken to be a short-range Coulomb potential together with a long-range linear potential modified by a harmonic-oscillator potential. Decays are studied using the quark pair creation model of Le Yaouanc et. al. The pair strength γ is replaced by kγ . This and the meson radius are the only parameters used in the calculation of the decays. Overall, we have a useful model, employing a small number of parameters, yet capable of yielding a description of the baryons in good accord with experimental data.
Baryon asymmetry in inflationary universe
The problem of the baryon asymmetry in inflationary universe is discussed. It is shown that the baryon asymmetry in inflationary universe under certain constrainsts on masses of superheavy bosons can be larger than that in the standard scenario. An important property of the model considered is that the final baryon asymmetry does not depend on initial conditions in the early universe in contrast to what occUrs in the standard scenario based on (B-L) conserving grand unified theories. The new scenario is realized in the framework of the SU(5) Coleman-Weinberg theory with the symmetry breaking
Baryon mapping of quark systems
Sambataro, M
1995-01-01
We discuss a mapping procedure from a space of colorless three-quark clusters into a space of elementary baryons and illustrate it in the context of a three-color extension of the Lipkin model recently developed. Special attention is addressed to the problem of the formation of unphysical states in the mapped space. A correspondence is established between quark and baryon spaces and the baryon image of a generic quark operator is defined both in its Hermitian and non-Hermitian forms. Its spectrum (identical in the two cases) is found to consist of a physical part containing the same eigenvalues of the quark operator in the cluster space and an unphysical part consisting only of zero eigenvalues. A physical subspace of the baryon space is also defined where the latter eigenvalues are suppressed. The procedure discussed is quite general and applications of it can be thought also in the correspondence between systems of 2n fermions and n bosons.
Baryon Instability in SUSY Models
Nath, Pran; Arnowitt, R.
1996-01-01
Comment: 14 pages, latex, 1 fig, to be published in proceedings of the International Workshop on " Future Prospects of Baryon Instability Search in p-Decay and n-nbar Oscillation Experiments", Oak Ridge, Tennessee, March 28-30,1996
Excitations of strange bottom baryons
Woloshyn, R M
2016-01-01
The ground state and first excited state masses of Omega(b) and Omega(bb) baryons are calculated in lattice QCD using dynamical 2+1 flavour gauge fields. A set of baryon operators employing different combinations of smeared quark fields was used in the framework of the variational method. Results for radial excitation energies were confirmed by carrying out a supplementary multiexponential fitting analysis. Comparison is made with quark model calculations.
Baryonic Operators for Lattice Simulations
Edwards, R; Fleming, G; Heller, U M; Morningstar, C J; Richards, D; Sato, I; Wallace, S
2004-01-01
The construction of baryonic operators for determining the N* excitation spectrum is discussed. The operators are designed with one eye towards maximizing overlaps with the low-lying states of interest, and the other eye towards minimizing the number of sources needed in computing the required quark propagators. Issues related to spin identification are outlined. Although we focus on tri-quark baryon operators, the construction method is applicable to both mesons and penta-quark operators.
Anomalous Dimensions of Conformal Baryons
Pica, Claudio
2016-01-01
We determine the anomalous dimensions of baryon operators for the three color theory as function of the number of massless flavours within the conformal window to the maximum known order in perturbation theory. We show that the anomalous dimension of the baryon is controllably small for a wide range of number of flavours. We also find that this is always smaller than the anomalous dimension of the fermion mass operator. These findings challenge the partial compositeness paradigm.
Galaxy Cluster Baryon Fractions Revisited
Gonzalez, Anthony H; Zabludoff, Ann I; Zaritsky, Dennis
2013-01-01
We measure the baryons contained in both the stellar and hot gas components for twelve galaxy clusters and groups at z~0.1 with M=1-5e14 Msun. This paper improves upon our previous work through the addition of XMM data, enabling measurements of the total mass and masses of each major baryonic component --- ICM, intracluster stars, and stars in galaxies --- for each system. We recover a relation for the stellar mass versus halo mass consistent with our previous result. We confirm that the partitioning of baryons between the stellar and hot gas components is a strong function of M500; the fractions of total mass in stars and X-ray gas within r500 scale as M500^-0.45 and M500^0.26, respectively. We also confirm that the combination of the BCG and intracluster stars is an increasingly important contributor to the stellar baryon budget in lower halo masses. We find a weak, but statistically significant, dependence of the total baryon fraction upon halo mass, scaling as M500^0.16. For M500>2e14, the total baryon fr...
Constraining spin-one color-octet resonances using CDF and ATLAS data
Zerwekh, Alfonso R. [Universidad Austral de Chile and Centro Cientifico-Tecnologico de Valparaiso, Instituto de Fisica, Facultad de Ciencias, Valdivia (Chile)
2010-12-15
In this paper, we study the production of spin-one color-octet resonances (colorons) at hadron colliders in a model independent way. We use dijets data measured by CDF (at {radical}(s)=1.96 TeV and L=1.13 pb{sup -1}) and ATLAS (at {radical}(s)=7 TeV and L=315 nb{sup -1}) collaborations at the Tevatron and the LHC respectively to impose limits on the coupling of colorons to fermions. We show that CDF data still produce the more stringent limits on the coloron coupling constant. (orig.)
Color Octet Electron Search Potential of the FCC Based e-p Colliders
Acar, Y C; Oner, B B; Sultansoy, S
2016-01-01
Resonant production of color octet electron, e_{8}, at the FCC based ep colliders has been analyzed. It is shown that e-FCC will cover much a wider region of e_{8} masses compared to the LHC. Moreover, with highest electron beam energy, e_{8} search potential of the e-FCC exceeds that of FCC pp collider. If e_{8} is discovered earlier by the FCC pp collider, e-FCC will give opportunity to handle very important additional information. For example, compositeness scale can be probed up to hundreds TeV region.
An upper bound on $P$-wave charmonium production via the color-octet mechanism
Trottier, Howard D.
1993-01-01
A factorization theorem for $P$-wave quarkonium production, recently derived by Bodwin, Braaten, Yuan and Lepage, is applied to $\\Upsilon \\to \\chi_{cJ} + X$, where $\\chi_{cJ}$ labels the ${}^3 P_J$ charmonium states. The widths for $\\chi_{cJ}$ production through color-singlet $P$-wave and color-octet $S$-wave $c \\bar c$ subprocesses are computed each to leading order in $\\alpha_s$. Experimental data on $\\Upsilon \\to J / \\psi + X$ is used to obtain an upper bound on a nonperturbative parameter...
Samples of approx.= 1900 identified protons and approx.= 500 Λ have been used to search for decuplet baryon production in e+e- annihilation at a c.m. energy of 34.4 GeV. The pπ+ and Λπsup(+-) invariant mass spectra contain no Δ or Σsup(*) signals. Upper limits, at 95% confidence level, are that less than 12% of all p and less than 26% of all Λ come from the decay of doubly charged Δ and singly charged Σsup(*) states respectively. These limits correspond to production rates of ++ and ++ and Σsup(*+-) is suppressed by a factor > or approx. 9 relative to octet baryons of the same strangeness. (orig.)
Samples of proportional1,900 identified protons and proportional500 Λ have been used to search for decuplet baryon production in e+e- annihilation at a c.m. energy of 34.4 GeV. The pπ4 and Λπsup(+-) invariant mass spectra contain no Δ or Σsup(*) signals. Upper limits, at 95% confidence level, are that less than 12% of all p and less than 26% of all Λ come from the decay of doubly charged Δ and singly charged Σsup(*) states respectively. These limits correspond to production rates of ++ and ++ and Σsup(*+-) is suppressed by a factor > or approx.9 relative to octet baryons of the same strangeness. (orig.)
Baryons and baryonic matter in four-fermion interaction models
In this work we discuss baryons and baryonic matter in simple four-fermion interaction theories, the Gross-Neveu model and the Nambu-Jona-Lasinio model in 1+1 and 2+1 space-time dimensions. These models are designed as toy models for dynamical symmetry breaking in strong interaction physics. Pointlike interactions (''four-fermion'' interactions) between quarks replace the full gluon mediated interaction of quantum chromodynamics. We consider the limit of a large number of fermion flavors, where a mean field approach becomes exact. This method is formulated in the language of relativistic many particle theory and is equivalent to the Hartree-Fock approximation. In 1+1 dimensions, we generalize known results on the ground state to the case where chiral symmetry is broken explicitly by a bare mass term. For the Gross-Neveu model, we derive an exact self-consistent solution for the finite density ground state, consisting of a one-dimensional array of equally spaced potential wells, a baryon crystal. For the Nambu- Jona-Lasinio model we apply the derivative expansion technique to calculate the total energy in powers of derivatives of the mean field. In a picture akin to the Skyrme model of nuclear physics, the baryon emerges as a topological soliton. The solution for both the single baryon and dense baryonic matter is given in a systematic expansion in powers of the pion mass. The solution of the Hartree-Fock problem is more complicated in 2+1 dimensions. In the massless Gross-Neveu model we derive an exact self-consistent solution by extending the baryon crystal of the 1+1 dimensional model, maintaining translational invariance in one spatial direction. This one-dimensional configuration is energetically degenerate to the translationally invariant solution, a hint in favor of a possible translational symmetry breakdown by more general geometrical structures. In the Nambu-Jona-Lasinio model, topological soliton configurations induce a finite baryon number. In contrast
Galaxy cluster baryon fractions revisited
Gonzalez, Anthony H. [Department of Astronomy, University of Florida, Gainesville, FL 32611-2055 (United States); Sivanandam, Suresh; Zabludoff, Ann I.; Zaritsky, Dennis [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)
2013-11-20
We measure the baryons contained in both the stellar and hot-gas components for 12 galaxy clusters and groups at z ∼ 0.1 with M = 1-5 × 10{sup 14} M {sub ☉}. This paper improves upon our previous work through the addition of XMM-Newton X-ray data, enabling measurements of the total mass and masses of each major baryonic component—intracluster medium, intracluster stars, and stars in galaxies—for each system. We recover a mean relation for the stellar mass versus halo mass, M{sub ⋆}∝M{sub 500}{sup −0.52±0.04}, that is 1σ shallower than in our previous result. We confirm that the partitioning of baryons between the stellar and hot-gas components is a strong function of M {sub 500}; the fractions of total mass in stars and X-ray gas within a sphere of radius r {sub 500} scale as f{sub ⋆}∝M{sub 500}{sup −0.45±0.04} and f{sub gas}∝M{sub 500}{sup 0.26±0.03}, respectively. We also confirm that the combination of the brightest cluster galaxy and intracluster stars is an increasingly important contributor to the stellar baryon budget in lower halo masses. Studies that fail to fully account for intracluster stars typically underestimate the normalization of the stellar baryon fraction versus M {sub 500} relation by ∼25%. Our derived stellar baryon fractions are also higher, and the trend with halo mass weaker, than those derived from recent halo occupation distribution and abundance matching analyses. One difference from our previous work is the weak, but statistically significant, dependence here of the total baryon fraction upon halo mass: f{sub bary}∝M{sub 500}{sup 0.16±0.04}. For M {sub 500} ≳ 2 × 10{sup 14}, the total baryon fractions within r {sub 500} are on average 18% below the universal value from the seven year Wilkinson Microwave Anisotropy Probe (WMAP) analysis, or 7% below for the cosmological parameters from the Planck analysis. In the latter case, the difference between the universal value and cluster baryon fractions is
Baryon Transition in Holographic QCD
Li, Siwen
2015-01-01
We propose a mechanism of holographic baryon transition in the Sakai-Sugimoto (SS) model: baryons in this model can jump to different states under the mediated effect of gravitons (or glueballs by holography). We consider a time-dependent gravitational perturbation from M5-brane solution of D=11 supergravity and by employing the relations between 11D M-theory and IIA string theory, we get its 10 dimensional counterpart in the SS model. Such a perturbation is received by the D4-branes wrapped on the $S^{4}$ part of the 10D background, namely the baryon vertex. Technically, baryons in the SS model are described by BPST instanton ansatz and their dynamics can be analyzed using the quantum mechanical system in the instanton's moduli space. In this way, different baryonic states are marked by quantum numbers of moduli space quantum mechanics. By holographic spirit, the gravitational perturbation enters the Hamiltonian as a time-dependent perturbation and it is this time-dependent perturbative Hamiltonian produces ...
Decuplet baryon masses in covariant baryon chiral perturbation theory
Ren, Xiu-Lei; Geng, Li-Sheng; Meng, Jie
2013-01-01
We present an analysis of the lowest-lying decuplet baryon masses in the covariant baryon chiral perturbation theory with the extended-on-mass-shell scheme up to next-to-next-to-next-to-leading order. In order to determine the $14$ low-energy constants, we perform a simultaneous fit of the $n_f=2+1$ lattice QCD data from the PACS-CS, QCDSF-UKQCD, and HSC Collaborations, taking finite-volume corrections into account self-consistently. We show that up to next-to-next-to-next-to-leading order on...
Baryon masses at second order in large-N chiral perturbation theory
We consider flavor breaking in the octet and decuplet baryon masses at second order in large-N chiral perturbation theory, where N is the number of QCD colors. We assume that 1/N∼1/NF∼ms/Λ>mu,d/Λ,αEM, where NF is the number of light quark flavors, and mu,d,s/Λ are the parameters controlling SU(NF) flavor breaking in chiral perturbation theory. We consistently include nonanalytic contributions to the baryon masses at orders mq3/2, m2qlnmq, and (mqlnmq)/N. The mq3/2 corrections are small for the relations that follow from SU(NF) symmetry alone, but the corrections to the large-N relations are large and have the wrong sign. Chiral power counting and large-N consistency allow a two-loop contribution at order m2qlnmq, and a nontrivial explicit calculation is required to show that this contribution vanishes. At second order in the expansion, there are eight relations that are nontrivial consequences of the 1/N expansion, all of which are well satisfied within the experimental errors. The average deviation at this order is 7 MeV for the ΔI=0 mass differences and 0.35 MeV for the ΔI≠0 mass differences, consistent with the expectation that the error is of order 1/N2∼10%. copyright 1996 The American Physical Society
Kalashnikova, Yu S
1996-01-01
The QCD-motivated constituent string model is extended to consider the baryon. The system of three quarks propagating in the confining background field is studied in the Wilson loop approach, and the effective action is obtained. The resulting Lagrangian at large interquark distances corresponds to the Mercedes Benz string configuration. Assuming the quarks to be heavy enough to allow the adiabatic separation of quark and string junction motion and using the hyperspherical expansion for the quark subsystem we write out and solve the classical equation of motion for the junction. We quantize the motion of the junction and demonstrate that the account of these modes leads to the effective "swelling" of the baryon in comparison with the standard potential picture. We discuss the effects of the finite gluonic correlation length which do not affect the excited states but appear to be substantial for the baryonic ground state, reducing the "swelling" considerably and leaving room to the short range Coulomb force in...
National Aeronautics and Space Administration — Analysis of NASA science data is analyzed to understand dynamic systems such as the sun, oceans, and Earth's climate as well as to look back in time to explore the...
Density-dependent effective baryon-baryon interaction from chiral three-baryon forces
Petschauer, Stefan; Kaiser, Norbert; Meißner, Ulf-G; Weise, Wolfram
2016-01-01
A density-dependent effective potential for the baryon-baryon interaction in the presence of the (hyper)nuclear medium is constructed, based on the leading (irreducible) three-baryon forces derived within SU(3) chiral effective field theory. We evaluate the contributions from three classes: contact terms, one-pion exchange and two-pion exchange. In the strangeness-zero sector we recover the known result for the in-medium nucleon-nucleon interaction. Explicit expressions for the Lambda-nucleon in-medium potential in (asymmetric) nuclear matter are presented. Our results are suitable for implementation into calculations of (hyper)nuclear matter. In order to estimate the low-energy constants of the leading three-baryon forces we introduce the decuplet baryons as explicit degrees of freedom and construct the relevant terms in the minimal non-relativistic Lagrangian. With these, the constants are estimated through decuplet saturation. Utilizing this approximation we provide numerical results for the effect of the ...
The question of baryon conservation
A modern version of the law of baryon conservation might read: the net number of baryons (ΣB-ΣB-bar) does not change spontaneously or in any known interactions. For a long time it was believed that protons are absolutely stable, and neutrons sufficiently strongly bound by nuclei were also considered absolutely stable. Then a few years ago the grand unified theories were proposed in which strong, weak and electromagnetic interactions are combined, leading to the possibility that protons decay. Their lifetime is predictable in some of these theories. An experiment by the Irvine-Michigan-Brookhaven Collaboration to detect proton decays is described. (UK)
Deforming baryons into confining strings
Hartnoll, S A; Hartnoll, Sean A.; Portugues, Ruben
2004-01-01
We find explicit probe D3-brane solutions in the infrared of the Maldacena-Nunez background. The solutions describe deformed baryon vertices: q external quarks are separated in spacetime from the remaining N-q. As the separation is taken to infinity we recover known solutions describing infinite confining strings in ${\\mathcal{N}}=1$ gauge theory. We present results for the mass of finite confining strings as a function of length. We also find probe D2-brane solutions in a confining type IIA geometry, the reduction of a G_2 holonomy M theory background. The interpretation of these solutions as deformed baryons/confining strings is not as straightforward.
Heavy Baryons and Exotics Spectrum
Karliner, Marek; Tornqvist, Nils A
2011-01-01
We discuss several highly accurate theoretical predictions for masses of baryons containing the b quark which have been recently confirmed by experimental data. Several predictions are given for additional properties of heavy baryons. We also discuss the two charged exotic resonances Z_b with quantum numbers of a (b bbar u ddbar) tetraquark, very recently reported by Belle in the channel [Upsilon(nS) \\pi^+, n=1,2,3]. Among possible implications are deeply bound I=0 counterparts of the Z_b-s and existence of a Sigma_b^+ Sigma_b^- dibaryon, a "beauteron".
Decuplet baryons in hot medium
Azizi, K
2016-01-01
The thermal properties of the light decuplet baryons are investigated in the framework of the thermal QCD sum rules. In particular, the behavior of the mass and residue of the $\\Delta$, $\\Sigma^{*}$, $\\Xi^{*}$ and $\\Omega$ baryons with respect to temperature are analyzed taking into account the additional operators coming up in the Wilson expansion at finite temperature. It is found that the mass and residue of these particles remain overall unaffected up to $T\\simeq150~MeV$ but, after this point, they start to diminish, considerably.
Baryonic spectroscopy and its immediate future
The quark model is reviewed briefly for baryons and the various versions of SU(6) symmetry which were proposed and used in connection with baryon spectroscopy are reviewed. A series of basic questions are reviewed which experimental work in this field should aim to settle, as a minimal program. One also heralds the beginning of a new baryon spectroscopy associated with psi physics
Baryon Resonance Analysis from SAID
Arndt, R A; Paris, M W; Strakovsky, I I; Workman, R L
2009-01-01
We discuss the analysis of data from piN elastic scattering and single pion photo- and electroproduction. The main focus is a study of low-lying non-strange baryon resonances. Here we concentrate on some difficulties associated with resonance identification, in particular the Roper and higher P11 states.
Magnetic monopoles and baryon decay
The scattering of a non-relativistic quark from a GUT monopole is affected by the anomalous magnetic moment of the quark. In order that monopole catalysis of baryon decay can occur, it must be assumed that the anomalous magnetic moment decreases sufficiently rapidly below the QCD scale. (author)
First moment of the flavour octet nucleon parton distribution function using lattice QCD
Alexandrou, C; Dinter, S; Drach, V; Hadjiyiannakou, K; Jansen, K; Koutsou, G; Vaquero, A
2015-01-01
We perform a lattice computation of the flavour octet contribution to the average quark momentum in a nucleon, $\\la x\\ra^{(8)} _{\\mu^2 = 4~\\gev^2 }$. In particular, we fully take the disconnected contributions into account in our analysis for which we use a generalization of the technique developed in \\cite{Dinter:2012tt}. We investigate systematic effects with a particular emphasis on the excited states contamination. We find that in the renormalization free ratio $\\frac{\\la x \\ra^{(3)}}{\\la x \\ra^{(8)}}$ (with $\\la x \\ra^{(3)}$ the non-singlet moment) the excited state contributions cancel to a large extend making this ratio a promising candidate for a comparison to phenomenological analyses. Our final result for this ratio is in agreement with the phenomenological value and we find, including systematic errors, $\\frac{\\la x \\ra^{(3)}}{\\la x \\ra^{(8)}} = 0.39(1)(4)$.
Alternative large Nc baryons and holography
In gauge theories in the limit of a large number Nc of colors baryons are usually described as heavy solitonic objects with mass of order Nc. We discuss an alternative large Nc description both directly in the field theory as well as using holography. In this alternative large Nc limit at least some of the baryons behave like mesons, that is they stay light even at large Nc and their interactions vanish in that limit. For Nc=3 these alternative large Nc baryons are equivalent to the standard baryons. In the holographic description it is manifest that the Regge slopes of mesons and alternative baryons are degenerate.
Alternative large Nc baryons and holography
Hoyos-Badajoz, Carlos
2009-01-01
In gauge theories in the limit of a large number Nc of colors, baryons are usually described as heavy solitonic objects with mass of order Nc. We discuss an alternative large Nc description both directly in the field theory as well as using holography. In this alternative large Nc limit at least some of the baryons behave like mesons, that is they stay light even at large Nc and their interactions vanish in that limit. For Nc=3 these alternative large Nc baryons are equivalent to the standard baryons. In the holographic description it is manifest that the Regge slopes of mesons and alternative baryons are degenerate.
Li, Jian; Schantz, Allen; Schwegler, Maureen; Shankar, Gopi
2011-01-25
We assessed the utility of the FortéBio Octet(®) system for detection of anti-drug antibodies (ADAs) against an investigational therapeutic human IgG1 monoclonal antibody (mAb), CNTO X. To understand the relative merits of this technology, key performance requirements were compared with two popularly accepted ADA detection methods, a step-wise bridging ELISA and a Meso Scale Discovery (MSD) homogeneous (single step binding) bridging ECLIA. When used to detect 13 monoclonal ADAs of varying affinities and one polyclonal ADA, all three methods demonstrated their greatest apparent sensitivity to the polyclonal sample (1, 6, and 130 ng/mL, respectively for ECLIA, ELISA, and Octet). Sensitivity to monoclonal ADAs tended to vary in accordance with their affinities, however, the sensitivity of the Octet method varied much less between ADAs. As a result, the above ranking became reversed such that Octet was the most and ELISA least sensitive for detection of low-affinity ADAs. With regard to drug tolerance, the presence of CNTO X could lead to false-negative assay results, although each method was affected to a different degree, with the Octet method tolerating up to 10 times more drug than the ECLIA method, which in turn tolerated up to 10 times more than the ELISA. Finally, the ECLIA and Octet methods were applied to the bioanalysis of cynomolgus monkey sera from a pre-clinical multiple dose study of CNTO X. Octet indicated 3 positive animals developed ADA as early as day 15 of the dosing phase while drug was present at nearly 1mg/mL. ECLIA detected only one of these, and only in a day 57 recovery sample after drug had cleared from circulation. We conclude that the Octet is a promising platform for detection of lower affinity ADAs and is particularly suitable for ADA detection when drug persists at levels that negatively impact bridging immunoassays. PMID:20869832
Heavy baryon production and decay
The branching ratio B(Λc→pK-π+) normalizes the production and decay of charmed and bottom baryons. At present, this crucial branching ratio is extracted dominantly from bar B→baryons analyses. This paper questions several of the underlying assumptions and predicts sizable bar B→D(*)N bar N'X transitions, which were traditionally neglected. It predicts B(Λc→pK-π+) to be larger (0.07±0.02) than the world average. Some consequences are briefly mentioned. Several techniques to measure B(Λc→pK-π+) are outlined with existing or soon available data samples. By equating two recent CLEO results, an appendix obtains B(D0→K-π+)=0.035±0.002, which is somewhat smaller than the current world average. copyright 1998 The American Physical Society
Bergstrom, L.
2001-01-01
The need for dark matter is briefly reviewed. A wealth of observational information points to the existence of a non-baryonic component. To the theoretically favoured candidates today belong axions, supersymmetric particles, and to some extent massive neutrinos. The theoretical foundation and experimental situation for each of these is reviewed. In particular, indirect detection methods of supersymmetric dark matter are described. Present experiments are just reaching the required sensitivity...
Baryons and Mesons with Beauty
Goldstein, Gary R.; Wali, Kameshwar C.
2007-01-01
Recent experimental findings of several mesons and baryons with "beauty" and "charm" as flavors remind us of the days when strangeness was discovered, and how its inclusion led to SU(3)-flavor symmetry with enormous success in the classification of the "proliferated" states into SU(3) multiplets. One of the key elements was the successful application of the first order perturbation in symmetry breaking, albeit what then appeared to be huge mass differences, and the prediction of new states th...
Transport coefficients of heavy baryons
Tolos, Laura; Torres-Rincon, Juan M.; Das, Santosh K.
2016-08-01
We compute the transport coefficients (drag and momentum diffusion) of the low-lying heavy baryons Λc and Λb in a medium of light mesons formed at the later stages of high-energy heavy-ion collisions. We employ the Fokker-Planck approach to obtain the transport coefficients from unitarized baryon-meson interactions based on effective field theories that respect chiral and heavy-quark symmetries. We provide the transport coefficients as a function of temperature and heavy-baryon momentum, and analyze the applicability of certain nonrelativistic estimates. Moreover we compare our outcome for the spatial diffusion coefficient to the one coming from the solution of the Boltzmann-Uehling-Uhlenbeck transport equation, and we find a very good agreement between both calculations. The transport coefficients for Λc and Λb in a thermal bath will be used in a subsequent publication as input in a Langevin evolution code for the generation and propagation of heavy particles in heavy-ion collisions at LHC and RHIC energies.
The QCD-motivated constituent string model is extended to consider the baryon. The system of three quarks propagating in a confining background field is studied in the Wilson loop approach, and the effective action is obtained. The resulting Lagrangian at large interquark distances corresponds to the Mercedes Benz string configuration. Under the assumption that quarks are sufficiently heavy to allow the adiabatic separation of quark and string-junction motions, the use of hyperspherical expansion for the quark subsystem makes it possible to write and solve the classical equation of motion for the junction. The motion of the junction is quantized, and it is shown that the effective ''swelling'' of the baryon in relation to the standard potential picture occurs as the result of taking these modes into account. Effects associated with a finite gluon-correlation length, which do not affect excited states, but which appear to be substantial for the baryon ground state, reducing the ''swelling'' considerably and leaving room to the short-range Coulomb force in the three-quark system, are discussed
Quayle, Paul C.; Blanton, Eric W.; Punya, Atchara; Junno, Grant T.; He, Keliang; Han, Lu; Zhao, Hongping; Shan, Jie; Lambrecht, Walter R. L.; Kash, Kathleen
2015-05-01
We investigate lattice ordering phenomena for the heterovalent ternaries that are based on the wurtzite lattice, under the constraint that the octet rule be preserved. We show that, with the single exception of a highly symmetric twinned structure, all allowed lattice orderings can be described by a pseudospin model corresponding to the two different stackings of A B A B rows of atoms in the basal plane that occur in the P n a 21 and P m c 21 crystal structures. First-principles calculations show that the difference in the energies of formation between these two structures is 13 ±3 meV/fu (formula unit) for ZnSnN2 and is an order of magnitude larger for ZnGeN2 and that for both materials the P m 31 structure, which contains only octet-rule-violating tetrahedra, has a significantly higher energy of formation and a signficantly lower band gap. We predict almost random stacking and wurtzitelike x-ray-diffraction spectra in the case of ZnSnN2, consistent with reported measurements. The octet-rule-preserving model of disorder proposed here predicts a band gap that for ZnSnN2 is relatively insensitive to ordering, in contrast to the prevailing model, which invokes the random placement of atoms on the cation sublattice. The violations of the octet rule in the latter model lead to significant narrowing of the band gap. The Raman and photoluminescence spectra of ZnSnN2 are interpreted in light of the ordering model developed here. The observation that ZnGeN2 orders in the P n a 21 structure under appropriate growth conditions is consistent with the larger difference in the energies of formation of the P n a 21 and P m c 21 structures for this material. The ordering model presented here has important implications for the optical, electronic, and lattice properties of all wurtzite-based heterovalent ternaries.
Faddeev study of heavy baryon spectroscopy
Garcilazo, H; Vijande, J
2007-01-01
We investigate the structure of heavy baryons containing a charm or a bottom quark. We employ a constituent quark model successful in the description of the baryon-baryon interaction which is consistent with the light baryon spectra. We solve exactly the three-quark problem by means of the Faddeev method in momentum space. Heavy baryon spectrum shows a manifest compromise between perturbative and nonperturbative contributions. The flavor dependence of the one-gluon exchange is analyzed. We assign quantum numbers to some already observed resonances and we predict the first radial and orbital excitations of all states with $J=1/2$ or 3/2. We combine our results with heavy quark symmetry and lowest-order SU(3) symmetry breaking to predict the masses and quantum numbers of six still non-measured ground-state beauty baryons.
The Heavy Baryon Physics by means LEP
This report describes the experimental research about the heavy baryons which were obtained in the last decade at LEP. The most important among them concern the lifetimes of beauty baryons. The methods of theoretical description of heavy hadrons together with the LEP experimental apparatus are also discussed. Heavy baryon studies are shown in a broader perspective of other LEP results: the test of the standard model and the latest measurements concerning the beauty mesons. (author)
Baryon Asymmetry, Inflation and Squeezed States
Bambah, Bindu A.; Chaitanya, K. V. S. Shiv; Mukku, C.
2006-01-01
We use the general formalism of squeezed rotated states to calculate baryon asymmetry in the wake of inflation through parametric amplification. We base our analysis on a B and CP violating Lagrangian in an isotropically expanding universe. The B and CP violating terms originate from the coupling of complex fields with non-zero baryon number to a complex background inflaton field. We show that a differential amplification of particle and anti-particle modes gives rise to baryon asymmetry.
Hadronic molecules in the heavy baryon spectrum
We study possible baryon molecules in the non-strange heavy baryon spectrum. We include configurations with a heavy-meson and a light baryon. We find several structures, in particular we can understand the Λc(2940) as a D*N molecule with JP = 3/2− quantum numbers. We also find D(*)Δ candidates for the recently discovered Xc(3250) resonance
Baryons with Two Heavy Quarks as Solitons
Bander, Myron; Subbaraman, Anand
1994-01-01
Using the chiral soliton model and heavy quark symmetry we study baryons containing two heavy quarks. If there exists a stable (under strong interactions) meson consisting of two heavy quarks and two light ones, then we find that there always exists a state of this meson bound to a chiral soliton and to a chiral anti-soliton, corresponding to a two heavy quark baryon and a baryon containing two heavy anti-quarks and five light quarks, or a ``heptaquark".
First moment of the flavour octet nucleon parton distribution function using lattice QCD
Alexandrou, Constantia [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; The Cyprus Institute, Nicosia (Cyprus). Computation-based Science and Technology Research Center (CaSToRC); Constantinou, Martha; Hadjiyiannakou, Kyriakos; Koutsou, Giannis [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Dinter, Simon [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Drach, Vincent [Univ. of Southern Denmark, Odense (Denmark). CP3-Origins and the Danish Institute for Advanced Study DIAS; Jansen, Karl [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; The Cyprus Institute, Nicosia (Cyprus). Computation-based Science and Technology Research Center (CaSToRC); Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Vaquero, Alejandro [INFN, Sezione di Milano-Bicocca, Milano (Italy); Collaboration: European Twisted Mass Collaboration
2015-03-15
We perform a lattice computation of the flavour octet contribution to the average quark momentum in a nucleon, left angle x right angle {sup (8)}{sub μ{sup 2}=4} {sub GeV{sup 2}}. In particular, we fully take the disconnected contributions into account in our analysis for which we use a generalization of the technique developed by S. Dinter et. al. (2012). We investigate systematic effects with a particular emphasis on the excited states contamination. We find that in the renormalization free ratio (left angle x right angle {sup (3)})/(left angle x right angle {sup (8)}) (with left angle x right angle {sup (3)} the non-singlet moment) the excited state contributions cancel to a large extend making this ratio a promising candidate for a comparison to phenomenological analyses. Our final result for this ratio is in agreement with the phenomenological value and we find, including systematic errors, (left angle x right angle {sup (3)})/(left angle x right angle {sup (8)})=0.39(1)(4).
CP violation with beautiful baryons
Dunietz, I. (European Organization for Nuclear Research, Geneva (Switzerland). Theory Div.)
1992-10-01
CP violation can be studied in modes of charmed or bottom baryons when a decay process is compared with its charge-conjugated partner. It can show up as a rate asymmetry and in a study of other decay parameters. Neither tagging nor time-dependences are required to observe CP violation with modes of baryons, in contrast to the conventional B{sup 0} modes. Numerous modes of bottom baryons have the potential to show large CP-violating effects within the Standard Model. Those effects can be substantial for modes with a D{sup 0}, which is seen in a final state that can also be fed from {anti D}{sup 0}. For instance, a comparison of the {Lambda}{sub b}{yields}{Lambda}D{sub CP}{sup 0} with the anti {Lambda}{sub b}{yields} anti {Lambda}D{sub CP}{sup 0} process can show sizeable CP violation. Here D{sub CP}{sup 0} denotes CP eigenstates of D{sup 0}, which occur at a few percent. Six related processes, such as {Lambda}{sub b}{yields}{Lambda}D{sup 0}, {Lambda}{sub b}{yields}{Lambda}{anti D}{sup 0}, {Lambda}{sub b}{yields}{Lambda}D{sub CP}{sup 0}, and their charge-conjugated counterparts, can extract {phi}, which is the most problematic angle of the unitarity triangle and which is conventionally probed with the B{sub s}{yields}{rho}{sup 0} K{sub S} asymmetry. Here D{sup 0} and anti D{sup 0} are identified by their charged kaon or lepton.
Doubly Heavy Tetraquarks and Baryons
Karliner Marek
2014-04-01
Full Text Available During the last three years strong experimental evidence from B and charm factories has been accumulating for the existence of exotic hadronic quarkonia, narrow resonances which cannot be made from a quark and an antiquark. Their masses and decay modes show that they contain a heavy quark-antiquark pair, but their quantum numbers are such that they must also contain a light quark-antiquark pair. The theoretical challenge has been to determine the nature of these resonances. The main possibilities are that they are either "genuine tetraquarks", i.e. two quarks and two antiquarks within one confinement volume, or "hadronic molecules" of two heavy-light mesons. In the last few months there as been more and more evidence in favor of the latter. I discuss the experimental data and its interpretation and provide fairly precise predictions for masses and quantum numbers of the additional exotic states which are naturally expected in the molecular picture but have yet to be observed. In addition, I provide arguments in favor of the existence of an even more exotic state – a hypothetical deuteron-like bound state of two heavy baryons. I also consider “baryon-like" states QQ' q¯q¯′$\\bar q\\bar q\\prime $, which if found will be direct evidence not just for near-threshold binding of two heavy mesons, but for genuine tetraquarks with novel color networks. I stress the importance of experimental search for doubly-heavy baryons in this context.
Quarks, baryons and chiral symmetry
Hosaka, Atsushi
2001-01-01
This book describes baryon models constructed from quarks, mesons and chiral symmetry. The role of chiral symmetry and of quark model structure with SU(6) spin-flavor symmetry are discussed in detail, starting from a pedagogic introduction. Emphasis is placed on symmetry aspects of the theories. As an application, the chiral bag model is studied for nucleon structure, where important methods of theoretical physics, mostly related to the semiclassical approach for a system of strong interactions, are demonstrated. The text is more practical than formal; tools and ideas are explained in detail w
Bergström, L
1999-01-01
The need for dark matter is briefly reviewed. A wealth of observational information points to the existence of a non-baryonic component. To the theoretically favoured candidates today belong axions, supersymmetric particles, and to some extent massive neutrinos. The theoretical foundation and experimental situation for each of these is reviewed. In particular, indirect detection methods of supersymmetric dark matter are described. Present experiments are just reaching the required sensitivity to discover or rule out some of these candidates, and major improvements are planned over the next few years.
The need for dark matter is briefly reviewed. A wealth of observational information points to the existence of a non-baryonic component. To the theoretically favoured candidates today belong axions, supersymmetric particles, and to some extent massive neutrinos. The theoretical foundation and experimental situation for each of these is reviewed. In particular, indirect detection methods of supersymmetric dark matter are described. Present experiments are just reaching the required sensitivity to discover or rule out some of these candidates, and major improvements are planned over the next few years
Beautiful Baryons from Lattice QCD
Alexandrou, C.; Borrelli, A; Güsken, S.; Jegerlehner, F.; K. Schilling; Siegert, G.; Sommer, R
1994-01-01
We perform a lattice study of heavy baryons, containing one ($\\Lambda_b$) or two $b$-quarks ($\\Xi_b$). Using the quenched approximation we obtain for the mass of $\\Lambda_b$ $$ M_{\\Lambda_b}= 5.728 \\pm 0.144 \\pm 0.018 {\\rm GeV}.$$ The mass splitting between the $\\Lambda_b$ and the B-meson is found to increase by about 20\\% if the light quark mass is varied from the chiral limit to the strange quark mass.
Baryon Form Factors at Threshold
Baldini Ferroli, Rinaldo [Museo Storico della Fisica e Centro Studi e Ricerche ' E. Fermi' , Rome (Italy); INFN, Laboratori Nazionali di Frascati, Frascati (Italy); Pacetti, Simone [INFN and Dipartimento di Fisica, Universita di Perugia, Perugia (Italy)
2012-04-15
An extensive study of the e{sup +}e{sup -}{yields}pp{sup Macron }BABAR cross section data is presented. Two unexpected outcomes have been found: the modulus of the proton form factor is normalized to one at threshold, i.e.: |G{sup p}(4M{sub p}{sup 2})|=1, as a pointlike fermion, and the resummation factor in the Sommerfeld formula is not needed. Other e{sup +}e{sup -} {yields} baryon-antibaryon cross sections show a similar behavior near threshold.
The good, the bad, and the baryon
We describe the incorporation of baryons into an effective theory of QCD at low energies. The baryon is not a Skyrmion, rather it consists of three valence quarks bound by effective gluon exchanges, enveloped in a meson cloud, which may possibly take the form of a chiral soliton. Some of the physical implications of these results are also discussed. (orig.)
Baryon spectroscopy and the omega minus
In this report, I will mainly discuss baryon resonances with emphasis on the discovery of the Ω-. However, for completeness, I will also present some data on the meson resonances which together with the baryons led to the uncovering of the SU(3) symmetry of particles and ultimately to the concept of quarks
Heavy baryons in the relativistic quark model
In the framework of the relativistic quasipotential quark model the mass spectrum of baryons with two heavy quarks is calculated. The quasipotentials for interactions of two quarks and of a quark with a scalar and axial vector diquark are evaluated. The bound state masses of baryons with JP=1/2+, 3/2+ are computed. (orig.)
Domain walls. II. Baryon-number generation
Domain walls present in the early universe due to a spontaneous breakdown of charge conjugation can leave behind net baryon number. SU/sub R/(2) instantons provide baryon nonconservation and the proton is effectively stable. Density perturbations (on scales large enough for galaxy formation) and monopole suppression can occur if walls dominate the energy density. Mechanisms for wall removal are discussed
Exploring the simplest purely baryonic decay processes
Geng, C Q; Rodrigues, Eduardo
2016-01-01
We propose to search for purely baryonic decay processes at the LHCb experiment. In particular, we concentrate on the decay $\\Lambda_b^0\\to p\\bar pn$, which is the simplest purely baryonic decay mode, with solely spin-1/2 baryons involved. We predict its decay branching ratio to be ${\\cal B}(\\Lambda_b^0\\to p\\bar pn)=(2.0^{+0.3}_{-0.2})\\times 10^{-6}$, which is sufficiently large to make the decay mode accessible to LHCb. Though not considered in general, purely baryonic decays could shed light on the puzzle of the baryon number asymmetry in the universe by means of a better understanding of the baryonic nature of our matter world. As such, they constitute a yet unexplored class of decay processes worth investigating. Our study can be extended to the purely baryonic decays of $\\Lambda_b^0\\to p\\bar p \\Lambda$, $\\Lambda_b^0\\to \\Lambda \\bar p\\Lambda$ and $\\Lambda_b^0\\to \\Lambda\\bar \\Lambda\\Lambda$, as well as other similar anti-triplet $b$-baryon decays, such as $\\Xi_b^{0,-}$.
Frishman, Y. (Weizmann Inst. of Science, Rehovoth (Israel). Dept. of Physics); Zakrzewski, W.J. (Durham Univ. (UK). Dept. of Mathematical Siences)
1989-12-18
We find multi-baryon states in two-dimensional quantum chromodynamics. We show that to bind two baryons the model must involve at least seven flavours. All calculations are performed in the strong coupling limit and the semiclassical approximation is employed in the derivation of the results. We briefly comment on the properties of the derived states. (orig.).
Baryonic masses based on the NJL model
We employ the Nambu-Jona-Lasinio model to determine the vacuum pressure on the quarks in a baryon and hence their density inside. Then we estimate the baryonic masses by implementing the local density approximation for the mean-field quark energies obtained in a uniform and isotropic system. We obtain a fair agreement with the experimental masses. (orig.)
Baryon symmetric big bang cosmology
Stecker, F. W.
1978-01-01
Both the quantum theory and Einsteins theory of special relativity lead to the supposition that matter and antimatter were produced in equal quantities during the big bang. It is noted that local matter/antimatter asymmetries may be reconciled with universal symmetry by assuming (1) a slight imbalance of matter over antimatter in the early universe, annihilation, and a subsequent remainder of matter; (2) localized regions of excess for one or the other type of matter as an initial condition; and (3) an extremely dense, high temperature state with zero net baryon number; i.e., matter/antimatter symmetry. Attention is given to the third assumption, which is the simplest and the most in keeping with current knowledge of the cosmos, especially as pertains the universality of 3 K background radiation. Mechanisms of galaxy formation are discussed, whereby matter and antimatter might have collided and annihilated each other, or have coexisted (and continue to coexist) at vast distances. It is pointed out that baryon symmetric big bang cosmology could probably be proved if an antinucleus could be detected in cosmic radiation.
Froggatt, C D
2005-01-01
It is proposed that dark matter could consist of compressed collections of atoms (or metallic matter) encapsulated into, for example, 20 cm big pieces of a different phase. The idea is based on the assumption that there exists at least one other phase of the vacuum degenerate with the usual one. Apart from the degeneracy of the phases we only assume Standard Model physics. The other phase has a Higgs VEV appreciably smaller than in the usual electroweak vacuum. The balls making up the dark matter are very difficult to observe directly, but inside dense stars may expand eating up the star and cause huge explosions (gamma ray bursts). The ratio of dark matter to ordinary baryonic matter is estimated to be of the order of the ratio of the binding energy per nucleon in helium to the difference between the binding energies per nucleon in heavy nuclei and in helium. Thus we predict approximately five times as much dark matter as ordinary baryonic matter!
Strange decays of nonstrange baryons
The strong decays of excited nonstrange baryons into the final states ΛK, ΣK, and for the first time into Λ(1405)K, Λ(1520)K, Σ(1385)K, ΛK*, and ΣK*, are examined in a relativized quark pair creation model. The wave functions and parameters of the model are fixed by previous calculations of Nπ and Nππ, etc., decays. The results show that it should be possible to discover several new negative parity excited baryons and confirm the discovery of several others by analyzing these final states in kaon production experiments. They also establish clear predictions for the relative strengths of certain states to decay to Λ(1405)K and Λ(1520)K, which can be tested to determine if a three-quark model of the Λ(1405)K is valid. The authors results compare favorably with the results of partial wave analyses of the limited existing data for the ΛK and ΣK channels. They do not find large ΣK decay amplitudes for a substantial group of predicted and weakly established negative-parity states, in contrast to the only previous work to consider decays of these states into the strange final states ΛK and ΣK