Quark confinement in a constituent quark model
International Nuclear Information System (INIS)
Langfeld, K.; Rho, M.
1995-01-01
On the level of an effective quark theory, we define confinement by the absence of quark anti-quark thresholds in correlation function. We then propose a confining Nambu-Jona-Lasinio-type model. The confinement is implemented in analogy to Anderson localization in condensed matter systems. We study the model's phase structure as well as its behavior under extreme conditions, i.e. high temperature and/or high density
Goldstone-Boson Dynamics for Constituent Quarks
Plessas, W.
2003-07-01
We address some essential features of the Goldstone-boson-exchange constituent quark model. Starting from its background we discuss the motivation for its construction and show its performance in light and strange baryon spectroscopy. Then we quote results from first applications of this type of constituent quark model in covariant calculations of electroweak nucleon form factors.
Quark solitons as constituents of hadrons
International Nuclear Information System (INIS)
Ellis, J.; Frishman, Y.; Hanany, A.; Karlinev, M.
1992-01-01
We exhibit static solutions of multi-flavour QCD in two dimensions that have the quantum numbers of baryons and mesons, constructed out of quark and anti-quark solitons. In isolation the latter solitons have infinite energy, corresponding to the presence of a string carrying the non-singlet colour flux off to spatial infinity. When N c solitons of this type are combined, a static, finite-energy, colour singlet solution is formed, corresponding to a baryon. Similarly, static meson solutions are formed out of a soliton and an anti-soliton of different flavours. The stability of the mesons against annihilation is ensured by flavour conservation. The static solutions exist only when the fundamental fields of the bosonized lagrangian belong to U(N c xN f ) rather than to SU(N c )xU(N f ). Discussion of flavour-symmetry breaking requires a careful treatment of the normal-ordering ambiguity. Our results can be viewed as a derivation of the constituent quark model in QCD 2 , allowing a detailed study of constituent mass generation and of the heavy-quark symmetry. (orig.)
Kaon quark distribution functions in the chiral constituent quark model
Watanabe, Akira; Sawada, Takahiro; Kao, Chung Wen
2018-04-01
We investigate the valence u and s ¯ quark distribution functions of the K+ meson, vK (u )(x ,Q2) and vK (s ¯)(x ,Q2), in the framework of the chiral constituent quark model. We judiciously choose the bare distributions at the initial scale to generate the dressed distributions at the higher scale, considering the meson cloud effects and the QCD evolution, which agree with the phenomenologically satisfactory valence quark distribution of the pion and the experimental data of the ratio vK (u )(x ,Q2)/vπ (u )(x ,Q2) . We show how the meson cloud effects affect the bare distribution functions in detail. We find that a smaller S U (3 ) flavor symmetry breaking effect is observed, compared with results of the preceding studies based on other approaches.
International Nuclear Information System (INIS)
Bhaduri, Partha Pratim; Chattopadhyay, Subhasis
2010-01-01
Differential elliptic flow v 2 (p T ) for identified hadrons is investigated in the FAIR energy regime, employing a hadronic-string transport model (UrQMD) as well as a partonic transport model (AMPT). It is observed that both models show a mass ordering of v 2 at low p T and a switch-over resulting in a baryon-meson crossing at intermediate p T . AMPT generates higher v 2 values compared to UrQMD. In addition, constituent quark number scaling behavior of elliptic flow is addressed. Scaling behavior in terms of the transverse momentum p T is found to be absent for both the partonic and the hadronic model. However, UrQMD and AMPT with a string melting scenario do exhibit an NCQ scaling of v 2 to varying degrees, with respect to the transverse kinetic energy KE T . But the default AMPT, where partonic scatterings are not included, does not show any considerable scaling behavior. A variable α is defined to quantify the degree of KE T scaling. We found that UrQMD gives better scaling than AMPT at FAIR.
Sivers function in constituent quark models
Scopetta, S.; Fratini, F.; Vento, V.
2008-01-01
A formalism to evaluate the Sivers function, developed for calculations in constituent quark models, is applied to the Isgur-Karl model. A non-vanishing Sivers asymmetry, with opposite signs for the u and d flavor, is found; the Burkardt sum rule is fulfilled up to 2 %. Nuclear effects in the extraction of neutron single spin asymmetries in semi-inclusive deep inelastic scattering off 3He are also evaluated. In the kinematics of JLab, it is found that the nuclear effects described by an Impulse Approximation approach are under control.
Do quarks play an explicit role as nuclear constituents ?
International Nuclear Information System (INIS)
Yamazaki, Toshimitsu.
1986-10-01
Experimental signatures for explicit roles of quarks as nuclear constituents are looked for. It is stressed that hyperons in nuclei may reveal unique information on nuclear interior and possible quark deconfinement. Future directions of hypernuclear spectroscopy are discussed. (author)
Constituent gluons and the static quark potential
Energy Technology Data Exchange (ETDEWEB)
Greensite, Jeff [San Francisco State Univ., CA (United States); Szczepaniak, Adam P. [Indiana Univ., Bloomington, IN (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
2016-04-01
We suggest that Hamiltonian matrix elements between physical states in QCD might be approximated, in Coulomb gauge, by "lattice-improved" tree diagrams; i.e. tree diagram contributions with dressed ghost, transverse gluon, and Coulomb propagators obtained from lattice simulations. Such matrix elements can be applied to a variational treatment of hadronic states which include constituent gluons. As an illustration and first application of this hybrid approach, we derive a variational estimate of the heavy quark potential for distances up to 2.5 fm. The Coulomb string tension in SU(3) gauge theory is about a factor of four times greater than the asymptotic string tension. In our variational approach, using for simplicity a single variational parameter, we can reduce this overshoot by nearly the factor required. The building blocks of our approach are Coulomb gauge propagators, and in this connection we present new lattice results for the ghost and transverse gluon propagators in position space.
Quark mass effects in quark number susceptibilities
International Nuclear Information System (INIS)
Graf, Thorben; Petreczky, Peter
2017-01-01
The quark degrees of freedom of the QGP with special focus on mass effects are investigated. A next-to-leading-order perturbation theory approach with quark mass dependence is applied and compared to lattice QCD results. (paper)
Energy Technology Data Exchange (ETDEWEB)
Kanki, T [Osaka Univ., Toyonaka (Japan). Coll. of General Education
1976-12-01
We present a quark-gluon-parton model in which quark-partons and gluons make clusters corresponding to two or three constituent quarks (or anti-quarks) in the meson or in the baryon, respectively. We explicitly construct the constituent quark state (cluster), by employing the Kuti-Weisskopf theory and by requiring the scaling. The quark additivity of the hadronic total cross sections and the quark counting rules on the threshold powers of various distributions are satisfied. For small x (Feynman fraction), it is shown that the constituent quarks and quark-partons have quite different probability distributions. We apply our model to hadron-hadron inclusive reactions, and clarify that the fragmentation and the diffractive processes relate to the constituent quark distributions, while the processes in or near the central region are controlled by the quark-partons. Our model gives the reasonable interpretation for the experimental data and much improves the usual ''constituent interchange model'' result near and in the central region (x asymptotically equals x sub(T) asymptotically equals 0).
Constituent quark mass and nucleon properties in nuclei
International Nuclear Information System (INIS)
Beyer, M.; Singh, S.K.
1986-01-01
It is shown that the Nolen-Schiffer anomaly, the quenching of gsub(A) and the increase in some electromagnetic properties of nucleons in nuclei can all be explained qualitatively in a constituent quark model if the quark mass is assumed to depend on its confinement size. (author)
From fundamental fields to constituent quarks and nucleon form factors?
International Nuclear Information System (INIS)
Coester, F.
1991-01-01
Constituent-quark models formulated in the frame work of nonrelativistic quantum mechanics have been successful in accounting for the mass spectra of mesons and baryons. Applications to elastic electron scattering require relativistic dynamics. Relativistic quantum mechanics of constituent quarks can be formulated by constructing a suitable unitary representation of the Poincare group on the three-quark Hilbert space. The mass and spin operators of this representation specify the relativistic model dynamics. The dynamics of fundamental quark fields, on the other hand, is specified by a Euclidean functional integral. In this paper, the author shows how the dynamics of the fundamental fields can be related in principle to the Hamiltonian dynamics of quark particles through the properties of the Wightman functions
Successes and failures of the constituent quark model
International Nuclear Information System (INIS)
Lipkin, H.J.
1982-01-01
Our approach considers the model as a possible bridge between QCD and the experimental data and examines its predictions to see where these succeed and where they fail. We also attempt to improve the model by looking for additional simple assumptions which give better fits to the experimental data. But we avoid complicated models with too many ad hoc assumptions and too many free parameters; these can fit everything but teach us nothing. We define our constituent quark model by analogy with the constituent electron model of the atom and the constituent nucleon model of the nucleus. In the same way that an atom is assumed to consist only of constituent electrons and a central Coulomb field and a nucleus is assumed to consist only of constituent nucleons hadrons are assumed to consist only of their constituent valence quarks with no bag, no glue, no ocean, nor other constituents. Although these constituent models are oversimplified and neglect other constituents we push them as far as we can. Atomic physics has photons and vacuum polarization as well as constituent electrons, but the constituent model is adequate for calculating most features of the spectrum when finer details like the Lamb shift are neglected. 54 references
Symmetries and aggregates of quarks as constituents of hadrons
International Nuclear Information System (INIS)
Kibler, M.
1982-07-01
The interest of the Lie algebra of the group SU(n) for the classification of hadrons and the description of some of their static properties is emphasized for n=3, 4, 6, 8. The cases n=3 and 4 allow to introduce the quark flavors (u,d,s,) and (u,d,c,s), respectively, and the consideration of the spin of hadrons leads to the chain SU(2m) contains SU(m) x SU(2). The hadrons are described as bound states or aggregates of quarks of type quark-quark-quark for baryons and quark-antiquark for mesons. The Pauli exclusion principle applied to the three-quark baryons requires the introduction of a new quantum number, the color: each flavor of quark then comes in three colors
Kaon-Nucleon scattering in a constituent quark model
International Nuclear Information System (INIS)
Lemaire, S.
2002-06-01
We have investigated Kaon-Nucleon (KN) interaction in a constituent quark model in the momentum range for the Kaon between 0 and 1 GeV/c in the laboratory frame. This study has been motivated by the fact that in an approach relying on a boson exchange mechanism the Bonn group was forced, in order to obtain good agreement with I = 0 s-wave phase shifts, to add the exchange of a short range fictitious repulsive scalar meson. This need for repulsion, whose range (∼ 0.2 fm) is smaller than the nucleon radius, clearly shows that the quark substructure of the nucleons and K + mesons cannot be neglected. The Kaon-Nucleon phase shifts are calculated in a quark potential model using the resonating group method (RGM). We have to cope with a five body problem with antisymmetrization with respect to the four ordinary quarks of the Kaon-Nucleon system. One requirement of our approach is that the quark-quark interaction must give a quite good description of the hadron spectra. One goal of the present work aims at determining the influence of a relativistic kinematics, in this constituent quark model, for the calculation of KN phase shifts. We have also investigated s, p, d, f, g waves KN elastic phase shifts and we have included a spin-orbit term in the quark-quark interaction. Then we have studied the influence of medium and long range exchange mechanism in the quark quark interaction on KN phase shifts. (author)
Deformed baryons: constituent quark model vs. bag model
International Nuclear Information System (INIS)
Iwamura, Y.; Nogami, Y.
1985-01-01
Recently Bhaduri et al. developed a nonrelativistic constituent quark model for deformed baryons. In that model the quarks move in a deformable mean field, and the deformation parameters are determined by minimizing the quark energy subject to the constraint of volume conservation. This constraint is an ad hoc assumption. It is shown that, starting with a bag model, a model similar to that of Bhaduri et al. can be constructed. The deformation parameters are determined by the pressure balance on the bag surface. There is, however, a distinct difference between the two models with respect to the state dependence of the ''volume''. Implications of this difference are discussed
KN interaction in a constituent quark model
International Nuclear Information System (INIS)
Labarsouque, J.; Leandri, J.; Silvestre Brac, B.
1997-01-01
The kaon-nucleon s-wave phase shift have been calculated in a quark potential model using the resonating group method. The Hill-Wheeler equation has been solved numerically without any parametrization of the KN relative wave-function. The I = 0 phase shift has been found in agreement with the experimental data. In the I = 1 channel too much repulsion has been obtained., probably due to the lack of medium-range boson exchange type attraction. In a second step, pion and sigma-type exchange have been incorporated in the calculation
Tensor Susceptibilities of the Vacuum from Constituent Quarks
International Nuclear Information System (INIS)
Broniowski, W.; Polyakov, M.; Goeke, K.; Hyun-Chul Kim
1998-01-01
We show that the constituent quark model leads to simple expression for the isoscalar and isovector tensor susceptibilities of the vacuum. The found values are negative and of magnitude compatible with QCD-sum-rule parametrizations of spectral densities in appropriate L=1-meson channels. (author)
Tensor Susceptibilities of the Vacuum from Constituent Quarks
Energy Technology Data Exchange (ETDEWEB)
Broniowski, W [The H. Niewodniczanski Institute of Nuclear Physics, Cracow (Poland); Polyakov, M; Goeke, K [Institute for Theoretical Physics II, Ruhr-Universitaet-Bochum, Bochum (Germany); Kim, Hyun-Chul [Pusan National University, Department of Physics, Pusan (Korea, Republic of)
1998-05-15
We show that the constituent quark model leads to simple expression for the isoscalar and isovector tensor susceptibilities of the vacuum. The found values are negative and of magnitude compatible with QCD-sum-rule parametrizations of spectral densities in appropriate L=1-meson channels. (author)
Polarized constituent quarks in NLO approximation
International Nuclear Information System (INIS)
Khorramian, Ali N.; Tehrani, S. Atashbar; Mirjalili, A.
2006-01-01
The valon representation provides a basis between hadrons and quarks, in terms of which the bound-state and scattering properties of hadrons can be united and described. We studied polarized valon distributions which have an important role in describing the spin dependence of parton distribution in leading and next-to-leading order approximation. Convolution integral in frame work of valon model as a useful tool, was used in polarized case. To obtain polarized parton distributions in a proton we need to polarized valon distribution in a proton and polarized parton distributions inside the valon. We employed Bernstein polynomial averages to get unknown parameters of polarized valon distributions by fitting to available experimental data
Electromagnetic splitting for mesons and baryons using dressed constituent quarks
International Nuclear Information System (INIS)
Silvestre-Brac, Bernard; Brau, Fabian; Semay, Claude
2003-01-01
Electromagnetic splittings for mesons and baryons are calculated in a formalism where the constituent quarks are considered as dressed quasiparticles. The electromagnetic interaction, which contains coulomb, contact and hyperfine terms, is folded with the quark electrical density. Two different types of strong potentials are considered. Numerical treatment is done very carefully and several approximations are discussed in detail. Our model contains only one free parameter and the agreement with experimental data is reasonable although it seems very difficult to obtain a perfect description in any case
Tetraquarks in a chiral constituent-quark model
International Nuclear Information System (INIS)
Vijande, J.; Fernandez, F.; Valcarce, A.; Silvestre-Brac, B.
2004-01-01
We analyze the possibility of heavy-light tetraquark bound states by means of a chiral constituent-quark model. The study is done in a variational approach. Special attention is paid to the contribution given by the different terms of the interacting potential and also to the role played by the different color channels. We find a stable state for both qq anti c anti c and qq anti b anti b configurations. Possible decay modes of these structures are analyzed. (orig.)
Tetraquarks in a chiral constituent-quark model
Energy Technology Data Exchange (ETDEWEB)
Vijande, J.; Fernandez, F.; Valcarce, A. [Grupo de Fisica Nuclear, Universidad de Salamanca, E-37008, Salamanca (Spain); Silvestre-Brac, B. [Institut des Sciences Nucleaires, 53 Avenue des Martyrs, F-38026, Grenoble Cedex (France)
2004-03-01
We analyze the possibility of heavy-light tetraquark bound states by means of a chiral constituent-quark model. The study is done in a variational approach. Special attention is paid to the contribution given by the different terms of the interacting potential and also to the role played by the different color channels. We find a stable state for both qq anti c anti c and qq anti b anti b configurations. Possible decay modes of these structures are analyzed. (orig.)
Various decays of some hadronic systems in constituent quark models
International Nuclear Information System (INIS)
Bonnaz, R.
2001-09-01
The topic of this study is the decay of mesons in constituent quark models. Those models as well as the various quark-antiquark interaction potentials are presented. Strong decay of a meson into two or three mesons is studied in the second part. The original 3 P o model is presented as well as the research of a vertex function γ(p) depending on the momentum for the created qq-bar pair. We show that a function γ(p) of constant+Gaussian type is superior than the constant usually used. The second part is dedicated to electromagnetic transitions studied through the emission of a real or a virtual photon. In the case of real photon emission, the different approximations found in the literature are reviewed and compared to the formalism going beyond the long wave length approximation. Mixing angles are tested for some mesons. In the case of virtual photon, the expression of decay width obtained by van Royen and Weisskopf is re-demonstrated and then improved by taking into account the quark momentum distribution inside the meson. An electromagnetic dressing of quarks is introduced that improves the results. All along this study, wave functions of various sophistication degrees are used. The results of decay widths are compared to a large bulk of experimental data. (author)
Current quarks and constituent-classification quarks: some questions and ideas
International Nuclear Information System (INIS)
Close, F.E.
1977-01-01
A brief introduction is given to the spin dependence of inelastic photo and electroproduction. Parton model predictions of Kuti and Weisskopf are then criticized and a paradox noted in connection with a sum rule of Bjorken. The resolution of this paradox raises several questions concerning the constituent and current quark approaches to resonance excitation. Particular attention is given to current algebra constraints, angular momentum in the nucleon, the x → 1 behavior of inelastic electroproduction, psi production and radiative decays
Hadron form factors in the constituent quark model
International Nuclear Information System (INIS)
Cardarelli, F.; Salme', G.; Simula, S.; Pace, E.
1998-01-01
Hadron electromagnetic form factors are evaluated in a light-front constituent quark model based on the eigenfunctions of a mass operator, including in the q-q interaction a confining term and a one-gluon-exchange term (OGE). The spin-dependent part of the interaction plays an essential role for obtaining both a proper fit of the experimental nucleon electromagnetic form factors and the faster than dipole decrease of the magnetic N-P 33 (1232) transition form factor. The effects of the D wave, produced by the tensor part of the OGE interaction, on the quadrupole and Coulomb N-P 33 (1232) transition form factors have been found to be negligible. (author)
Chiral bag model with constituent quarks: topological and nontopological decisions
International Nuclear Information System (INIS)
Malakhov, I.Yu.; Sveshnikov, K.A.; Fedorov, S.M.; Khalili, M.F.
2002-01-01
The three-phase modification of the hybrid chiral bag containing along with asymptotic freedom and hadronization phases and also intermediate phase of the constituent quarks is considered. The self-consistent solutions of the equations of the model in the (1 + 1)-dimensional case are determined with an account of the fermion vacuum polarization effects. The bag renormalized complete energy is studied as a function of the parameters characterizing the bag geometry and its topological (baryon) charge. It is shown that for nonzero topological charge there exists the whole series of configurations representing the local minima of the bag complete energy and containing all three phases, whereas the bag energy minimum in the nontopological case corresponds to zero dimensions of the area corresponding to asymptotic freedom phase [ru
Double parton correlations in Light-Front constituent quark models
Directory of Open Access Journals (Sweden)
Rinaldi Matteo
2015-01-01
Full Text Available Double parton distribution functions (dPDF represent a tool to explore the 3D proton structure. They can be measured in high energy proton-proton and proton nucleus collisions and encode information on how partons inside a proton are correlated among each other. dPFDs are studied here in the valence quark region, by means of a constituent quark model, where two particle correlations are present without any additional prescription. This framework allows to understand the dynamical origin of the correlations and to clarify which, among the features of the results, are model independent. Use will be made of a relativistic light-front scheme, able to overcome some drawbacks of the previous calculation. Transverse momentum correlations, due to the exact treatment of the boosts, are predicted and analyzed. The role of spin correlations is also shown. Due to the covariance of the approach, some symmetries of the dPDFs are seen unambigously. For the valence sector, also the study of the QCD evolution of the model results, which can be performed safely thanks to the property of good support, has been also completed.
International Nuclear Information System (INIS)
Xu Shu-Sheng; Shi Chao; Cui Zhu-Fang; Zong Hong-Shi; Jiang Yu
2015-01-01
Generally speaking, the quark propagator is dependent on the quark chemical potential in the dense quantum chromodynamics (QCD). By means of the generating functional method, we prove that the quark propagator actually depends on p_4 + iμ from the first principle of QCD. The relation between quark number density and quark condensate is discussed by analyzing their singularities. It is concluded that the quark number density has some singularities at certain μ when T = 0, and the variations of the quark number density as well as the quark condensate are located at the same point. In other words, at a certain μ the quark number density turns to nonzero, while the quark condensate begins to decrease from its vacuum value. (paper)
On equal constituent quark masses in different heavy quarkonia potential models
International Nuclear Information System (INIS)
Lewin, K.; Motz, G.
1989-01-01
In a representative number of more or less QCD-motivated QQ-bar potentials the simultaneous transformations of potentials V' j (r)=V i (r)-V i (r 0 ), m' Qi +1/2V j (r 0 ) (i -model index) introduce approximately equal constituent quark masses m' Qi ≅m Q (Q=b,c) for all considered models. The known model independence of m bi -m ci is explained and the influence of the transformation on data reproduction is studied. 16 refs.; 4 figs.; 1 tab
Constituent quarks and the gluonic contribution to the spin of the nucleon
International Nuclear Information System (INIS)
Eldahoumi, Gamal
2009-01-01
The internal structure of the nucleon is more complicated than expected in a simple quark model. In particular, the portion of the nucleon spin carried by the spins of the quarks is not, as expected, of the order of one, but according to the experimental data much smaller. In this thesis we study the spin structure of the proton in quantum chromodynamics. The constituent quark model, based on SU(6), predicts that the spin of the proton should be carried by the quarks, in disagreement with the experiments. It appears strange, that the theoretical model works so well for the magnetic moments of the nucleons, but not for the spin, although the spin and the magnetic moments are closely related to each other. We shall resolve this problem by assuming that the constituent quarks have an internal structure on their own. Thus a constituent quark has a dynamical structure, and we can introduce notions like the quark or gluon distributions inside a constituent quark. In the light of new experimental data from HERMES, COMPASS, JLab, and RHIC-spin, the current status of our knowledge of the spin structure is discussed in the two theoretical frameworks: the naive parton model, and the QCD evolved parton model. QCD a is successful theory, both in perturbative and non-perturbative regions, but the spin of the nucleon still needs to be explained within QCD. (orig.)
Constituent quarks and the gluonic contribution to the spin of the nucleon
Energy Technology Data Exchange (ETDEWEB)
Eldahoumi, Gamal
2009-01-15
The internal structure of the nucleon is more complicated than expected in a simple quark model. In particular, the portion of the nucleon spin carried by the spins of the quarks is not, as expected, of the order of one, but according to the experimental data much smaller. In this thesis we study the spin structure of the proton in quantum chromodynamics. The constituent quark model, based on SU(6), predicts that the spin of the proton should be carried by the quarks, in disagreement with the experiments. It appears strange, that the theoretical model works so well for the magnetic moments of the nucleons, but not for the spin, although the spin and the magnetic moments are closely related to each other. We shall resolve this problem by assuming that the constituent quarks have an internal structure on their own. Thus a constituent quark has a dynamical structure, and we can introduce notions like the quark or gluon distributions inside a constituent quark. In the light of new experimental data from HERMES, COMPASS, JLab, and RHIC-spin, the current status of our knowledge of the spin structure is discussed in the two theoretical frameworks: the naive parton model, and the QCD evolved parton model. QCD a is successful theory, both in perturbative and non-perturbative regions, but the spin of the nucleon still needs to be explained within QCD. (orig.)
Color exotic constituent quarks and their possible manifestations in hadron spectroscopy
International Nuclear Information System (INIS)
Anisovich, V.V.
1985-01-01
Hypothetical colour-exotic constituent (or dressed) quarks are discussed. It is shown that the data on the excited baryons with Jsup(P)=1/2 + , 3/2 + and excited mesons with Jsup(P)=0 - , 1 - are in reasonable agreement with the hypothesis of the existence of colour-exotic quark in the colour state 6
Constituent quarks in nuclear matter and the Nolen-Schiffer anomaly
International Nuclear Information System (INIS)
Lutz, M.; Lee, H.K.; Weise, W.
1991-01-01
We investigate the density dependence of the neutron-proton mass difference using the Nambu and Jona-Lasinio model in combination with the Isgur-Karl constituent quark model. The decrease of the constituent quark masses with increasing density reduces the n-p mass difference in the proper way to help resolving the Nolen-Schiffer anomaly. We point out however, that in the presence of vector interactions, this effect is less pronounced than previously suggested. (orig.)
In quest of a relativistic constituent quark model - some constructive remarks
International Nuclear Information System (INIS)
Hofsaess, T.; Schierholz, G.
1978-01-01
The set-up of a relativistic constituent quark model in four dimensions is one of the outstanding problems in particle physics. For the time being this involves a great deal of model building which, very probably, will not change in the near future. In this paper we shall offer some general remarks which might help putting such models into shape. Most of the earlier attempts are found controversial. In particular, a conventional quark constituent interpretation could not be recovered. (orig.) [de
Testing the constituent quark model in KN scattering
Energy Technology Data Exchange (ETDEWEB)
Lemaire, S. E-mail: lemaire@cenbg.in2p3.fr; Labarsouque, J.; Silvestre-Brac, B
2003-02-10
The kaon-nucleon S, P, D, F, G waves phase shifts have been calculated using a non-relativistic quark potential model and the resonating group method (RGM). The calculation has been performed using quark-quark potential which both includes gluon, pion and sigma exchanges and reproduces as well as possible the meson spectrum. The agreement obtained with the existing experimental phase shifts is quite poor. The results are also compared with a previous calculation based only on gluon exchanges at the quark level.
Testing the constituent quark model in KN scattering
International Nuclear Information System (INIS)
Lemaire, S.; Labarsouque, J.; Silvestre-Brac, B.
2003-01-01
The kaon-nucleon S, P, D, F, G waves phase shifts have been calculated using a non-relativistic quark potential model and the resonating group method (RGM). The calculation has been performed using quark-quark potential which both includes gluon, pion and sigma exchanges and reproduces as well as possible the meson spectrum. The agreement obtained with the existing experimental phase shifts is quite poor. The results are also compared with a previous calculation based only on gluon exchanges at the quark level
Electromagnetic properties of baryons in the constituent quark model
International Nuclear Information System (INIS)
Warns, M.
1992-01-01
The electromagnetic properties of baryons are investigated in the framework of a relativized quark model. The model includes beyond the usual single quark transition ansatz relativistic effects due to the strong interaction and confinement forces between the quarks. Furthermore the center-of-mass motion of the three-quark system is separated off in a Lorentz-invariant way. All relativistic correction terms are obtained by expanding the corresponding relativistic expressions in powers of the quark velocity. In this way recoil effects on the electromagnetic interaction between the photon and the baryon could be explicitly studied. Using the harmonic oscillator wavefunctions with the configuration mixing from the Isgur-Karl model, the form factors of the nucleon and the electromagnetic transition amplitudes both for longitudinally and transversely polarized photons are calculated for the most important baryon resonances. An extension to baryons involving strange quarks is also considered. Comparisons are made with the results of the nonrelativistic quark model and with some other approaches. (orig.)
The constituent quark model the spectrum of mesons
International Nuclear Information System (INIS)
Shojaei, M.R.; Rajabi, A.A.; Hasanabadi, H.
2007-01-01
Full text: We calculate exact solution of the Schroedinger equation analytically for a meson consisting of a quark and antiquark, considering the interaction potential between the particles as a combination of two potentials, a potential due to color charge and an oscillatory potential as confining potential. in this paper, first consider potential between quarks as a function of radios x, thus we assume this potential as a central potential. This potential is derived from that the central potential. This potential is derived from that the quark see itself under influence of another quark, in this case central potential is considered as: V(x)=ax 2 -c/x. Potential is obtained from interaction between a quark and an antiquary. The source of it is color charge and ax 2 potential plays confining potential. Because this potential shows oscillations of one quark to another quark in the distance x from it.. In addition to the above potentials we consider the spin-spin, spin - isospin and isospin - isospin interactions as perturbing potentials, and calculate the mass of the mesons for each potential separately finally using the equivalence of mass-energy we calculate the mass of the mesons
Parton distributions and EMC ratios of the 6Li nucleus in the constituent quark exchange model
Modarres, M.; Hadian, A.
2017-10-01
While the constituent quark model (CQM), in which the quarks are assumed to be the complex objects, is used to calculate the parton distribution functions of the iso-scalar lithium-6 (6Li) nucleus, the u-d constituent quark distribution functions of the 6Li nucleus are evaluated from the valence quark exchange formalism (VQEF) for the A = 6 iso-scalar system. After computing the valence quark, sea quark, and gluon distribution functions in the constituent quark exchange model (CQEM, i.e., CQM +VQEF), the nucleus structure function is calculated for the 6Li nucleus at the leading order (LO) and the next-to-leading-order (NLO) levels to extract the European muon collaboration (EMC) ratio, at different hard scales, using the standard Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGALP) evolution equations. The outcomes are compared with those of our previous works and the available NMC experimental data, and various physical points are discussed. It is observed that the present EMC ratios are considerably improved compared with those of our previous works, in which only the valence quark distributions were considered to calculate the EMC ratio, and are closer to the NMC data. Finally, it is concluded that at a given appropriate hard scale, the LO approximation may be enough for calculating the nucleus EMC ratio.
Nucleon form factors at high q2 within constituent quark models
International Nuclear Information System (INIS)
Desplanques, B.; Silvestre-Brac, B.; Cano, F.; Noguera, S.; Gonzalez, P.; .
2000-01-01
The nucleon form factors are calculated using a non-relativistic description in terms of constituent quarks. The emphasis is put on present numerical methods used to solve the three-body problem in order to reliably predict the expected asymptotic behavior of form factors. Nucleon wave functions obtained in the hyperspherical formalism or employing Faddeev equations have been considered. While a q -8 behavior is expected at high q for a quark-quark force behaving like 1/r at short distances, it is found that the hyper central approximation in the hyperspherical formalism (K = 0) leads to a q -7 behavior. An infinite set of waves would be required to get the correct behavior. Solutions of the Faddeev equations lead to the q -8 behavior. The coefficient of the corresponding term, however, depends on the number of partial waves retained in the Faddeev amplitude. The convergence to the asymptotic behavior has also been studied. Approximate expressions characterizing this one have been derived. From the comparison with the most complete Faddeev calculation, a validity range is inferred for restricted calculations. Refs. 46 (author)
Multiplicity of secondaries in hadron-nucleus collisions and constituent quark rescattering
International Nuclear Information System (INIS)
Shabelsky, Yu.M.; Shekhter, V.M.
1980-01-01
A ratio of the relativistic secondary multiplicities for hadron-nucleus and hadron-nucleon interactions, Rsub(s)(hA), is considered in the central region and a part of the target nucleus fragmentation region. The multiplicities are obtained from the experimental average numbers of relativistic charged or negative particles by subtraction of the projectile fragment numbers estimated theoretically. Two hypotheses on the A dependence of the secondary multiplicity in a constituent quark interaction with a nucleus are discussed. An assumption that this multiplicity is independent of A leads to Rsub(s)(hA) = antiνsub(hA)/antiνsub(qA). An alternative assumption that the qA multiplicity increases with A due to quark rescattering from several nucleons gives Rsub(s)(hA) = antiνsub(hA). Comparison with experiment in the former case requires a great number of positively charged hadrons, probably protons, emitted from the nucleus. This number must rise significantly with both A and incident energy. The latter hypothesis is consistent with all data on as well as in pA collisions but disagrees by approximately 20% with in π - A interactions. (author)
Constraints on constituent quark masses from potential models
International Nuclear Information System (INIS)
Silvestre-Brac, B.
1998-01-01
Starting from reasonable hypotheses, the magnetic moments for the baryons are revisited dat the light of general space wave functions. They allow to put very severe bounds on the quark masses as derived from usual potential models. The experimental situation cannot be explained in the framework of such models. (author)
Spin content of constituent quarks and one-spin asymmetries in inclusive processes
International Nuclear Information System (INIS)
Troshin, S.M.; Tyurin, N.E.
1995-01-01
A mechanism for one-spin asymmetries observed in inclusive hadron production is considered. The main role belongs to the orbital angular momentum of the quark-antiquark cloud in the internal structure of constituent quarks. The origin of the asymmetries in pion production is a result of retaining this internal angular orbital momentum by the perturbative phase of QCD under transition from the non-perturbative phase is proved. The non-perturbative hadron structure is based on the results of chiral quark models. 33 refs.; 8 figs
Low energy constituent quark and pion effective couplings in a weak external magnetic field
Braghin, Fábio L.
2018-03-01
An effective model with pions and constituent quarks in the presence of a weak external background electromagnetic field is derived by starting from a dressed one gluon exchange quark-quark interaction. By applying the auxiliary field and background field methods, the structureless pion limit is considered to extract effective pion and constituent quark couplings in the presence of a weak magnetic field. The leading terms of a large quark and gluon masses expansion are obtained by resolving effective coupling constants which turn out to depend on a weak magnetic field. Two pion field definitions are considered for that. Several relations between the effective coupling constants and parameters can be derived exactly or in the limit of very large quark mass at zero and weak constant magnetic field. Among these ratios, the Gell-Mann-Oakes-Renner and the quark level Goldberger-Treiman relations are obtained. In addition to that, in the pion sector, the leading terms of Chiral Perturbation Theory coupled to the electromagnetic field are recovered. Some numerical estimates are provided for the effective coupling constants and parameters.
Constituent quark model for nuclear stopping in high energy nuclear collisions
International Nuclear Information System (INIS)
Choi, T.K.; Maruyama, M.; Takagi, F.
1997-01-01
We study nuclear stopping in high energy nuclear collisions using the constituent quark model. It is assumed that wounded nucleons with a different number of interacted quarks hadronize in different ways. The probabilities of having such wounded nucleons are evaluated for proton-proton, proton-nucleus, and nucleus-nucleus collisions. After examining our model in proton-proton and proton-nucleus collisions and fixing the hadronization functions, it is extended to nucleus-nucleus collisions. It is used to calculate the rapidity distribution and the rapidity shift of final-state protons in nucleus-nucleus collisions. The computed results are in good agreement with the experimental data on 32 S+ 32 S at E lab =200A GeV and 208 Pb+ 208 Pb at E lab =160A GeV. Theoretical predictions are also given for proton rapidity distribution in 197 Au+ 197 Au at √(s)=200A GeV (BNL-RHIC). We predict that the nearly baryon-free region will appear in the midrapidity region and the rapidity shift is left-angle Δy right-angle=2.24
KN phase shifts in a constituent quark model
International Nuclear Information System (INIS)
Lemaire, S.; Labarsouque, J.; Silvestre-Brac, B.
2001-01-01
In a first step, the I=1 and I=0 kaon-nucleon s-wave phase shifts have been calculated in a quark potential model using the resonating group method (RGM) and a relativistic kinematics. The spinless Salpeter equation has been solved numerically using the Fourier grid hamiltonian method. The results have been compared to the nonrelativistic ones. For each isospin channel the phase shifts obtained are not so far from the nonrelativistic results. Then, K-nucleon p, d, f, g-waves phase shifts have been calculated using a nonrelativistic kinematics
Bethe-Salpeter dynamics and the constituent mass concept for heavy quark mesons
International Nuclear Information System (INIS)
Souchlas, N.; Stratakis, D.
2010-01-01
The definition of a quark as heavy requires a comparison of its mass with the nonperturbative chiral symmetry breaking scale which is about 1 GeV (Λ χ ∼1 GeV) or with the scale Λ QCD ∼0.2 GeV that characterizes the distinction between perturbative and nonperturbative QCD. For quark masses significantly larger than these scales, nonperturbative dressing effects, or equivalently nonperturbative self-energy contributions, and relativistic effects are believed to be less important for physical observables. We explore the concept of a constituent mass for heavy quarks in the Dyson-Schwinger equations formalism, for light-heavy and heavy-heavy quark mesons by studying their masses and electroweak decay constants.
Low-lying 1/2-hidden strange pentaquark states in the constituent quark model
Institute of Scientific and Technical Information of China (English)
Hui Li; Zong-Xiu Wu; Chun-Sheng An; Hong Chen
2017-01-01
We investigate the spectrum of the low-lying 1/2-hidden strange pentaquark states,employing the constituent quark model,and looking at two ways within that model of mediating the hyperfine interaction between quarks-Goldstone boson exchange and one gluon exchange.Numerical results show that the lowest 1/2-hidden strange pentaquark state in the Goldstone boson exchange model lies at ～ 1570 MeV,so this pentaquark configuration may form a notable component in S11(1535) if the Goldstone boson exchange model is applied.This is consistent with the prediction that S11 (1535) couples very strongly to strangeness channels.
The quark mass and baryon numbers of empty chiral bags
International Nuclear Information System (INIS)
Jezabek, M.; Zalewski, K.
1984-01-01
We show that for spherical chiral bags the baryon number of the Dirac vacuum inside the bag does not depend on quark masses. Thus, the sum of the baryon numbers of an empty chiral bag and the skyrmion surrounding the bag is an integer, which depends on the boundary condition on the surface of the bag. This extends the result obtained by Goldstone and Jaffe for massless quarks. (orig.)
Possible D(*) anti D(*) and B(*) anti B(*) molecular states in the extended constituent quark models
International Nuclear Information System (INIS)
Yang, You-Chang; Tan, Zhi-Yun; Ping, Jialun; Zong, Hong-Shi
2017-01-01
The possible neutral D (*) anti D (*) and B (*) anti B (*) molecular states are studied in the framework of the constituent quark models, which is extended by including the s-channel one-gluon exchange. Using different types of quark-quark potentials, we solve the four-body Schroedinger equation by means of the Gaussian expansion method. The bound states of D (*) anti D (*) with J PC = 1 ++ , 2 ++ and B (*) anti B (*) with J PC = 0 ++ , 1 +- , 1 ++ , 2 ++ are obtained. The molecular states D* anti D with J PC = 1 ++ and B* anti B with J PC = 1 +- are good candidates for X(3872) and Z 0 b (10610), respectively. The dependence of the results on the model parameters is also discussed. (orig.)
Constituent quarks and systematic errors in mid-rapidity charged multiplicity dNch/dη distributions
Tannenbaum, M. J.
2018-01-01
Centrality definition in A + A collisions at colliders such as RHIC and LHC suffers from a correlated systematic uncertainty caused by the efficiency of detecting a p + p collision (50 ± 5% for PHENIX at RHIC). In A + A collisions where centrality is measured by the number of nucleon collisions, Ncoll, or the number of nucleon participants, Npart, or the number of constituent quark participants, Nqp, the error in the efficiency of the primary interaction trigger (Beam-Beam Counters) for a p + p collision leads to a correlated systematic uncertainty in Npart, Ncoll or Nqp which reduces binomially as the A + A collisions become more central. If this is not correctly accounted for in projections of A + A to p + p collisions, then mistaken conclusions can result. A recent example is presented in whether the mid-rapidity charged multiplicity per constituent quark participant (dNch/dη)/Nqp in Au + Au at RHIC was the same as the value in p + p collisions.
International Nuclear Information System (INIS)
Rozanska, M.; Jezabek, M.
1991-04-01
Three version of a model with colour excitations of constituent quarks are examined using inclusive leading proton and antiproton spectra in nuclear interactions at high energies. The comparison with experimental data excludes the models in which fragmentation into leading final hadrons depends only on the colour charge of constituents in an intermediate system. (author)
Low-lying 1/2- hidden strange pentaquark states in the constituent quark model
Li, Hui; Wu, Zong-Xiu; An, Chun-Sheng; Chen, Hong
2017-12-01
We investigate the spectrum of the low-lying 1/2- hidden strange pentaquark states, employing the constituent quark model, and looking at two ways within that model of mediating the hyperfine interaction between quarks - Goldstone boson exchange and one gluon exchange. Numerical results show that the lowest 1/2- hidden strange pentaquark state in the Goldstone boson exchange model lies at ˜1570 MeV, so this pentaquark configuration may form a notable component in S 11(1535) if the Goldstone boson exchange model is applied. This is consistent with the prediction that S 11(1535) couples very strongly to strangeness channels. Supported by National Natural Science Foundation of China (11675131, 11645002), Chongqing Natural Science Foundation (cstc2015jcyjA00032) and Fundamental Research Funds for the Central Universities (SWU115020)
Strange mesonic transition form factor in the chiral constituent quark model
International Nuclear Information System (INIS)
Ito, H.; Ramsey-Musolf, M.J.
1998-01-01
The form factor g ρπ (S) (Q 2 ) of the strange vector current transition matrix element left-angle ρ|bar sγ μ s|π right-angle is calculated within the chiral quark model. A strange vector current of the constituent U and D quarks is induced by kaon radiative corrections and this mechanism yields the nonvanishing values of g ρπ (S) (0). The numerical result at the photon point is consistent with the one given by the φ-meson dominance model, but the falloff in the Q 2 dependence is faster than the monopole form factor. Mesonic radiative corrections are also examined for the electromagnetic ρ-to-π and K * -to-K transition amplitudes. copyright 1998 The American Physical Society
Quark flavour conserving violations of the lepton number
Binétruy, Pierre; Lavignac, Stephane; Savoy, C A
1998-01-01
We study supersymmetric models of lepton and baryon number violation based on an abelian family gauge group. Due to possible lepton-Higgs mixing, the lepton violating couplings are related to the Yukawa couplings and may be generated by them even if they were absent in the original theory. Such terms may be dominant and are not given by the naive family charge counting rules. This enhancement mechanism can provide an alignment between lepton-number violating terms and Yukawa couplings: as a result they conserve quark flavour. A natural way of suppressing baryon number violation in this class of models is also proposed.
Improving the quark number susceptibilities for staggered fermions
International Nuclear Information System (INIS)
Gavai, Rajiv V.
2003-01-01
Quark number susceptibilities approach their ideal gas limit at sufficiently high temperatures. As in the case of other thermodynamic quantities, this limit itself is altered substantially on lattices with small temporal extent, N t = 4-8, making it thus difficult to check the validity of perturbation theory. Unlike other observables, improving susceptibilities or number densities is subject to constraints of current conservation and absence of chemical potential (μ) dependent divergences. We construct such an improved number density and susceptibility for staggered fermions and show that they approximate the continuum ideal gas limit better on small temporal lattices
Topological and nontopological solutions for the chiral bag model with constituent quarks
International Nuclear Information System (INIS)
Sveshnikov, K.; Malakhov, I.; Khalili, M.; Fedorov, S.
2002-01-01
The three-phase version of the hybrid chiral bag model, containing the phase of asymptotic freedom, the hadronization phase as well as the intermediate phase of constituent quarks is proposed. For this model the self-consistent solutions of different topology are found in (1 + 1)D with due regard for fermion vacuum polarization effects. The renormalized total energy of the bag is studied as a function of its geometry and topological charge. It is shown that in the case of nonzero topological charge there exists a set of configurations being the local minima of the total energy of the bag and containing all the three phases, while in the nontopological case the minimum of the total energy of the bag corresponds to vanishing size of the phase of asymptotic freedom
Constituent quarks and charge particle production in heavy-ion collisions
International Nuclear Information System (INIS)
Mishra, Aditya Nath; Mazumder, Rakesh; Sahoo, Raghunath; Nandi, Basanta Kumar
2012-01-01
Relativistic heavy-ion collisions aims at producing a state of matter which is governed by partonic degree of freedom. The pseudorapidity density of particle multiplicity and transverse energy are the key observables which provide the properties of matter produced in heavy-ion collisions. Study of their dependence on centrality and collision energy is of paramount importance to understand the particle production mechanism. This may provide insight into the partonic phase that might be created in nuclear collisions. Here, in a constituent quarks framework, charged particle and transverse energy production in heavy-ion collisions are studied both as a function of centrality and collision energy, and hence the study gives a prediction for Pb + Pb collisions
Energy Technology Data Exchange (ETDEWEB)
Albaladejo, M.; Fernandez-Soler, P.; Nieves, J.; Ortega, P.G. [Centro Mixto CSIC-Universidad de Valencia, Instituto de Fisica Corpuscular (IFIC), Institutos de Investigacion de Paterna, Aptd. 22085, Valencia (Spain)
2017-03-15
The discovery of the D{sup *}{sub s0}(2317) and D{sub s1}(2460) resonances in the charmed-strange meson spectra revealed that formerly successful constituent quark models lose predictability in the vicinity of two-meson thresholds. The emergence of non-negligible effects due to meson loops requires an explicit evaluation of the interplay between Q anti q and (Q anti q)(q anti q) Fock components. In contrast to the c anti s sector, there is no experimental evidence of J{sup P} = 0{sup +}, 1{sup +} bottom-strange states yet. Motivated by recent lattice studies, in this work the heavy-quark partners of the D{sub s0}{sup *}(2317) and D{sub s1}(2460) states are analyzed within a heavy meson chiral unitary scheme. As a novelty, the coupling between the constituent quark-model P-wave anti B{sub s} scalar and axial mesons and the anti B{sup (*)}K channels is incorporated employing an effective interaction, consistent with heavy-quark spin symmetry, constrained by the lattice energy levels. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Shekhter, V [AN SSSR, Leningrad. Inst. Yadernoj Fiziki
1981-04-01
The history is described of the concept of quarks, ie., hypothetical particles of which,hadrons (strongly interacting particles) are believed to consist. The quark properties differ from those of known elementary particles. The electric charge of quarks is 1/3 and 2/3 of the electron charge and they obviously only exist inside hadrons. Quark existence is generally recognized because it has been confirmed by experimental verification of predictions made using a quark model.
Hard-Thermal-Loop QCD thermodynamics and quark number susceptibility
Directory of Open Access Journals (Sweden)
Mogliacci Sylvain
2014-04-01
Full Text Available The weak-coupling expansion of the QCD pressure is known up to the order g6 log g. However, at experimentally relevant temperatures, the corresponding series is poorly convergent. In this proceedings, we discuss at which extent the gauge-invariant resummation scheme, Hard-Thermal-Loop perturbation theory (HTLpt, improves the apparent convergence. We first present HTLpt results for QCD thermodynamic functions up to three-loop order at vanishing chemical potential. Then, we report a preliminary HTLpt result of one-loop quark number susceptibility, probing the finite density equation of state. Our results are consistent with lattice data down to 2 − 3Tc, reinforcing the weakly-coupled quasiparticle picture in the intermediate coupling regime.
Quark-number susceptibility, thermodynamic sum rule, and the hard thermal loop approximation
International Nuclear Information System (INIS)
Chakraborty, Purnendu; Mustafa, Munshi G.; Thoma, Markus H.
2003-01-01
The quark number susceptibility, associated with the conserved quark number density, is closely related to the baryon and charge fluctuations in the quark-gluon plasma, which might serve as signature for the quark-gluon plasma formation in ultrarelativistic heavy-ion collisions. In addition to QCD lattice simulations, the quark number susceptibility has been calculated recently using a resummed perturbation theory (hard thermal loop resummation). In the present work we show, based on general arguments, that the computation of this quantity neglecting hard thermal loop vertices contradicts the Ward identity and violates the thermodynamic sum rule following from quark number conservation. We further show that the hard thermal loop perturbation theory is consistent with the thermodynamic sum rule
Constituent quarks and enhancement of multi-strange baryons in heavy-ion collisions
International Nuclear Information System (INIS)
Behera, Nirbhay Kumar; Nandi, Basanta Kumar; Sahoo, Raghunath
2011-01-01
Heavy-ion collisions at relativistic energies aim to produce a state of matter which is governed by partonic degrees of freedom, known as Quark-Gluon Plasma (QGP). In the central rapidity region, strangeness enhancement has been proposed as a potential signature of QGP. It has been observed that a quark participant scaling of the multi-strange baryon production and also a strangeness scaling of the enhancement. This confirms that the partonic degrees of freedom is playing a major role in the particle production mechanism and may therefore significantly determine the formation of QGP in heavy ion collisions
Constituent quarks and multi-strange baryon production in heavy-ion collisions
International Nuclear Information System (INIS)
Sahoo, Raghunath; Behera, Nirbhay K.; Nandi, Basanta K.; Varma, Raghava
2009-01-01
Relativistic heavy-ion collisions aim at creating matter at extreme conditions of energy density and temperature which is governed by the partonic degrees of freedom called Quark-Gluon Plasma (QGP). In the early phase of ultra-relativistic heavy ion collisions, when a hot and dense region is formed in the core of the reaction zone, different quark flavors are produced copiously. The produced matter then undergoes transverse expansion and the produced particles suffer multiple scattering among themselves. The formation of the hadrons from the partonic phase is accomplished through further expansion and cooling of the system
International Nuclear Information System (INIS)
Jacob, M.
1982-01-01
This chapter discusses interactions only at the constituent level, as observed in hadron-hadron collisions. It defines quarks and gluons as constituents of the colliding hadrons, reviews some applications of perturbative OCD, discussing in turn lepton pair production, which in lowest order approximation corresponds to the Drell-Yan process. It investigates whether quark-quark interactions could not lead to some new color structure different from those prevalent for known baryons and mesons, which could be created in hadron interactions, and whether color objects (not specifically quarks or gluons) could not appear as free particles. Discussed is perturbative QCD in hadron collisions; the quark approach to soft processes; and new color structures. It points out that perturbative QCD has been at the origin of much progress in the understanding of hadron interactions at the constituent level
The baryonic spectrum in a constituent quark model including a three-body force
International Nuclear Information System (INIS)
Desplanques, B.; Gignoux, C.; Silvestre-Brac, B.; Gonzalez, P.; Navarro, J.; Noguera, S.
1992-01-01
We analyze, within a non-relativistic quark model, the low energy part of the baryonic spectrum in the octet and decuplet flavour representations. The relevance of a strong Coulomb potential is emphasized in order to explain its general features. The addition of a three-body force allows to solve the 'Roper puzzle', giving a consistent explanation to its relative position in the spectrum. (orig.)
Bound nucleon structure function in the picture of relativistic constituent quarks
International Nuclear Information System (INIS)
Grigoryan, L.A.; Shakhbazyan, V.A.
1987-01-01
The structure function F 2N of nucleons in the deuterium, carbon and iron nuclei is calculated as a function of Q 2 in two approaches: taking into account the nucleon swelling in nuclei due to the partial deconfinement of quarks in nuclear medium; in the conventional approach of nuclear physics, taking into account the getting off the mass shell of the bound nucleon and Fermi motion in nucleons. It is shown that the conventional approach of nuclear physics does not explain the EMC effect in the region of small x
Two-colour QCD at finite fundamental quark-number density and related theories
International Nuclear Information System (INIS)
Hands, S.J.; Kogut, J.B.; Morrison, S.E.; Sinclair, D.K.
2001-01-01
We are simulating SU(2) Yang-Mills theory with four flavours of dynamical quarks in the fundamental representation of SU(2) 'colour' at finite chemical potential, μ for quark number, as a model for QCD at finite baryon number density. In particular we observe that for μ large enough this theory undergoes a phase transition to a state with a diquark condensate which breaks quark-number symmetry. In this phase we examine the spectrum of light scalar and pseudoscalar bosons and see evidence for the Goldstone boson associated with this spontaneous symmetry breaking. This theory is closely related to QCD at finite chemical potential for isospin, a theory which we are now studying for SU(3) colour
Two-colour QCD at finite fundamental quark-number density and related theories
International Nuclear Information System (INIS)
Hands, S. J.; Kogut, J. B.; Morrison, S. E.; Sinclair, D. K.
2000-01-01
We are simulating SU(2) Yang-Mills theory with four flavours of dynamical quarks in the fundamental representation of SU(2) colour at finite chemical potential, p for quark number, as a model for QCD at finite baryon number density. In particular we observe that for p large enough this theory undergoes a phase transition to a state with a diquark condensate which breaks quark-number symmetry. In this phase we examine the spectrum of light scalar and pseudoscalar bosons and see evidence for the Goldstone boson associated with this spontaneous symmetry breaking. This theory is closely related to QCD at finite chemical potential for isospin, a theory which we are now studying for SU(3) colour
The quark-hadron transition in systems with net baryon number
International Nuclear Information System (INIS)
Olive, K.A.; Harvard Univ., Cambridge, MA
1982-01-01
The transition from quark matter to hadronic matter is examined in systems with arbitrary chemical potentials corresponding to net baryon number. In the hardron phase, both a Reid-type potential for nucleons and the ππ potential derived from Weinberg's effective lagrangian have been included. In the quark phase, a linear confining potential has been considered. Results are most sensitive to the slope of the confining potential, although qualitatively the behavior of the thermodynamic properties remain unchanged. The critical baryon density is found to remain roughly constant for all temperatures below the critical temperature, Tsub(c), then falls rapidly to zero as T → Tsub(c). Below Tsub(c) this density is about 30n 0 for K = 0.18 GeV 2 (the slope of the quark potential) and 23n 0 for K = 0.10 GeV 2 . (orig.)
Energy Technology Data Exchange (ETDEWEB)
Yang, You-Chang [Nanjing University, Department of Physics, Nanjing (China); Zunyi Normal University, School of Physics and Electronic Science, Zunyi (China); Institute of Theoretical Physics, CAS, State Key Laboratory of Theoretical Physics, Beijing (China); Tan, Zhi-Yun [Zunyi Normal University, School of Physics and Electronic Science, Zunyi (China); Ping, Jialun [Nanjing Normal University, Department of Physics, Nanjing (China); Zong, Hong-Shi [Nanjing University, Department of Physics, Nanjing (China); Institute of Theoretical Physics, CAS, State Key Laboratory of Theoretical Physics, Beijing (China)
2017-09-15
The possible neutral D{sup (*)} anti D{sup (*)} and B{sup (*)} anti B{sup (*)} molecular states are studied in the framework of the constituent quark models, which is extended by including the s-channel one-gluon exchange. Using different types of quark-quark potentials, we solve the four-body Schroedinger equation by means of the Gaussian expansion method. The bound states of D{sup (*)} anti D{sup (*)} with J{sup PC} = 1{sup ++}, 2{sup ++} and B{sup (*)} anti B{sup (*)} with J{sup PC} = 0{sup ++}, 1{sup +-}, 1{sup ++}, 2{sup ++} are obtained. The molecular states D* anti D with J{sup PC} = 1{sup ++} and B* anti B with J{sup PC} = 1{sup +-} are good candidates for X(3872) and Z{sup 0}{sub b}(10610), respectively. The dependence of the results on the model parameters is also discussed. (orig.)
International Nuclear Information System (INIS)
Tyapkin, A.A.
1976-01-01
The problem is raised on the interpretation of quarks having fractional quantum numbers as structural quasi-particles. A new composite model is proposed on the basis of the fundamental triplet representation of fermions having integral quantum numbers
Compound quarks and gluons and parton confinement (proposal of a different approach)
International Nuclear Information System (INIS)
Krolikowski, W.
1978-01-01
The author develops further the compound model proposed in 1971, where coloured quarks are factorized into elementary constituents carrying separately the flavour and colour quantum numbers and obeying the 'compensating' wrong statistics. An 'effective quantum chromodynamics' is conjectured, where both coloured quarks and vector gluons (which obey good statistics) are factorized into elementary constituents obeying wrong statistics. Then the Pauli connection of spin and statistics confines these elementary constituents within bound states obeying good statistics. In the parton model approximation with these elementary constituents as partons it prevents also coloured quarks and vector gluons from appearing as free particles. The expected confinement violation for coloured quarks and vector gluons and the observed scaling violation have here a common origin, namely the clustering of elementary constituents inside hadrons. The basic difference between leptons and quarks is related in this model to wrong statistics of elementary constituents involved in the quark structure. (Auth.)
Quark number density and susceptibility calculation with one correction in mean field potential
International Nuclear Information System (INIS)
Singh, S. Somorendro
2016-01-01
We calculate quark number density and susceptibility of a model which has one loop correction in mean field potential. The calculation shows continuous increasing in the number density and susceptibility up to the temperature T = 0.4 GeV. Then the value of number density and susceptibility approach to the lattice result for higher value of temperature. The result indicates that the calculated values of the model fit well and the result increase the temperature to reach the lattice data with the one loop correction in the mean field potential. (author)
Variable-flavor-number scheme in analysis of heavy-quark electro-production data
International Nuclear Information System (INIS)
Alekhin, S.; Bluemlein, J.; Klein, S.; Moch, S.
2009-08-01
We check the impact of the factorization scheme employed in the calculation of the heavy-quark deep-inelastic scattering (DIS) electro-production on the PDFs determined in the NNLO QCD analysis of the world inclusive neutral-current DIS data combined with the ones on the neutrino-nucleon DIS di-muon production and the fixed-target Drell-Yan process. The charm-quark DIS contribution is calculated in the general-mass variable-flavor-number (GMVFN) scheme: At asymptotically large values of the momentum transfer Q it is given by the zero-mass 4-flavor scheme and at the value of Q equal to the charm-quark mass it is smoothly matched with the 3-flavor scheme using the Buza-Matiounine-Smith-van Neerven prescription. The PDFs obtained in this variant of the fit are very similar to the ones obtained in the fit with a 3-flavor scheme employed. Our 5-flavor PDFs derived from the 3-flavor ones using the NNLO matching conditions are used to calculate the rates of W ± /Z and t anti t production at the Tevatron collider and the LHC at NNLO. (orig.)
Tidal Love numbers of neutron and self-bound quark stars
International Nuclear Information System (INIS)
Postnikov, Sergey; Prakash, Madappa; Lattimer, James M.
2010-01-01
Gravitational waves from the final stages of inspiraling binary neutron stars are expected to be one of the most important sources for ground-based gravitational wave detectors. The masses of the components are determinable from the orbital and chirp frequencies during the early part of the evolution, and large finite-size (tidal) effects are measurable toward the end of inspiral, but the gravitational wave signal is expected to be very complex at this time. Tidal effects during the early part of the evolution will form a very small correction, but during this phase the signal is relatively clean. The accumulated phase shift due to tidal corrections is characterized by a single quantity related to a star's tidal Love number. The Love number is sensitive, in particular, to the compactness parameter M/R and the star's internal structure, and its determination could provide an important constraint to the neutron star radius. We show that Love numbers of self-bound strange quark matter stars are qualitatively different from those of normal neutron stars. Observations of the tidal signature from coalescing compact binaries could therefore provide an important, and possibly unique, way to distinguish self-bound strange quark stars from normal neutron stars. Tidal signatures from self-bound strange quark stars with masses smaller than 1M · are substantially smaller than those of normal stars owing to their smaller radii. Thus tidal signatures of stars less massive than 1M · are probably not detectable with Advanced LIGO. For stars with masses in the range 1-2M · , the anticipated efficiency of the proposed Einstein telescope would be required for the detection of tidal signatures.
''Follow that quark!'' (and other exclusive stories)
International Nuclear Information System (INIS)
Carroll, A.S.
1987-01-01
Quarks are considered to be the basic constituents of matter. In a series of recent experiments, Carroll studied exclusive reactions as a means of determining the interactions between quarks. Quantum Chromo-dynamics (QCD) is the modern theory of the interaction of quarks. This theory explains how quarks are held together via the strong interaction in particles known as hadrons. Hadrons consisting of three quarks are called baryons. Hadrons made up of a quark and an antiquark are called mesons. In his lecture, Carroll describes what happens when two hadrons collide and scatter to large angles. The violence of the collision causes the gluons that bind the quarks in a particular hadron to temporarily lose their grip on particular quarks. Quarks scramble toward renewed unity with other quarks, and they undergo rearrangement, which generally results in additional new particles. A two-body exclusive reaction has occurred when the same number of particles exist before and after the collisions. At large angles these exclusive reactions are very rare. The labels on the quarks known as flavor enable the experimenter to follow the history of individual quarks in detail during these exclusive reactions. Carroll describes the equipment used in the experiment to measure short distance, hard collisions at large angles. The collisions he discusses occur when a known beam of mesons or protons collide with a stationary proton target. Finally, Carroll summarizes what the experiments have shown from the study of exclusive reactions and what light some of their results shed on the theory of QCD
Compositeness of quarks and leptons
International Nuclear Information System (INIS)
Peskin, M.E.
1981-01-01
I review along grand lines the theoretical ideas associated with the notion that quarks and leptons are composite. I first discuss various constituent pictures which have been proposed to account for the quantum numbers of the observed quarks and leptons, a study I call the Quantum Numerology. I then discuss some new theoretical developments of the past two years which bear on the subject of composite fermions and which make plausible (or rule out) some of the major dynamical assumptions of these constituent models. Finally, I discuss the consequences of the compositeness of quarks and leptons by setting up a series of scenarios for this compositeness and exploring, for each scenario, its experimental implications. (orig./HSI)
Quantum numbers of anti-grand-unified-theory Higgs fields from the quark-lepton spectrum
International Nuclear Information System (INIS)
Froggatt, C.D.; Nielsen, H.B.; Smith, D.J.
2002-01-01
A series of Higgs field quantum numbers in the anti-grand-unification model, based on the gauge group SMG 3 xU(1) f , is tested against the spectrum of quark and lepton masses and mixing angles. A more precise formulation of the statement that the couplings are assumed of order unity is given. It is found that the corrections coming from this more precise assumption do not contain factors of the order of the number of colors, N c =3, as one could have feared. We also include a combinatorial correction factor, taking account of the distinct internal orderings within the chain Feynman diagrams in our statistical estimates. Strictly speaking our model predicts that the uncertainty in its predictions and thus the accuracy of our fits should be ±60%. Many of the best fitting quantum numbers give a higher accuracy fit to the masses and mixing angles, although within the expected fluctuations in a χ 2 . This means that our fit is as good as it can possibly be
B{sup ¯}{sub s}→K semileptonic decay from an Omnès improved constituent quark model
Energy Technology Data Exchange (ETDEWEB)
Albertus, C. [Departamento de Física Atómica, Nuclear y Molecular e Instituto Carlos I de Física Teórica y Computacional, Universidad de Granada, Avenida de Fuentenueva s/n, E-18071 Granada (Spain); Hernández, E. [Departamento de Física Fundamental e IUFFyM, Universidad de Salamanca, Plaza de la Merced s/n, E-37008 Salamanca (Spain); Hidalgo-Duque, C.; Nieves, J. [Instituto de Física Corpuscular (IFIC), Centro Mixto CSIC-Universidad de Valencia, Institutos de Investigación de Paterna, Apartado 22085, E-46071 Valencia (Spain)
2014-11-10
We study the f{sup +} form factor for the semileptonic B{sup ¯}{sub s}→K{sup +}ℓ{sup −}ν{sup ¯}{sub ℓ} decay in a constituent quark model. The valence quark estimate is supplemented with the contribution from the B{sup ¯⁎} pole that dominates the high q{sup 2} region. We use a multiply-subtracted Omnès dispersion relation to extend the quark model predictions from its region of applicability near q{sub max}{sup 2}=(M{sub B{sub s}}−M{sub K}){sup 2}∼23.75 GeV{sup 2} to all q{sup 2} values accessible in the physical decay. To better constrain the dependence of f{sup +} on q{sup 2}, we fit the subtraction constants to a combined input from previous light cone sum rule by Duplancic and Melic (2008) [11] and the present quark model results. From this analysis, we obtain Γ(B{sup ¯}{sub s}→K{sup +}ℓ{sup −}ν{sup ¯}{sub ℓ})=(5.47{sub −0.46}{sup +0.54})|V{sub ub}|{sup 2}×10{sup −9} MeV, which is about 10% and 20% higher than the predictions based on Lattice QCD and QCD light cone sum rules respectively. The former predictions, for both the form factor f{sup +}(q{sup 2}) and the differential decay width, lie within the 1σ band of our estimated uncertainties for all q{sup 2} values accessible in the physical decay, except for a quite small region very close to q{sub max}{sup 2}. Differences with the light cone sum results for the form factor f{sup +} are larger than 20% in the region above q{sup 2}=15 GeV{sup 2}.
International Nuclear Information System (INIS)
Matveev, V.A.; Tavkhelidze, A.N.
2006-01-01
A brief review is given of the priority works which were mainly carried out at the Laboratory of Theoretical Physics, JINR, and devoted to the introduction to hadron physics of the concept of color and colored quarks, and to the description of hadrons in the framework of the model of quasi-free quarks. These ideas play a key role in the modern theory of strong interactions - quantum chromodynamics
Perturbation theory of the quark-gluon plasma at finite temperature and baryon number density
International Nuclear Information System (INIS)
Anon.
1984-01-01
At very high energy densities, hadronic matter becomes an almost ideal gas of quarks and gluons. In these circumstances, the effects of particle interactions are small, and to some order in perturbation theory are computable by methods involving weak coupling expansions. To illustrate the perturbative methods which may be used to compute the thermodynamic potential, the results and methods which are employed to compute to first order in α/sub s/ are reviewed. The problem of the plasmon effect, and the necessity of using non-perturbative methods when going beyond first order in α/sub s/ in evaluating the thermodynamic potential are discussed. The results at zero temperature and finite baryon number density to second order in α/sub s/ are also reviewed. The method of renormalization group improving the weak coupling expansions by replacing the expansion by an expansion in a temperature and baryon number density dependent coupling which approaches zero at high energy densities is discussed. Non-perturbative effects such as instantons are briefly mentioned and the breakdown of perturbation theory for the thermodynamical at order α/sub s/ 3 for finite temperature is presented
Baryons in the unquenched quark model
Energy Technology Data Exchange (ETDEWEB)
Bijker, R.; Díaz-Gómez, S. [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, AP 70-543, 04510 Mexico DF (Mexico); Lopez-Ruiz, M. A. [Physics Department and Center for Exploration of Energy and Matter, Indiana University, Bloomington, IN 47408 (United States); Santopinto, E. [Istituto Nazionale di Fisica Nucleare, Sezione di Genova, via Dodecaneso 33, I-16146 Italy (Italy)
2016-07-07
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 {sup 3}P{sub 0} quark-antiquark pair-creation mechanism. Particular attention is paid to the spin and flavor content of the proton, magnetic moments and β decays of octet baryons.
Important configurations in six-quark N-N states. II. Current quark model
International Nuclear Information System (INIS)
Stancu, F.; Wilets, L.
1989-01-01
Quark basis states constructed from molecular-type orbitals were shown previously to be more convenient to use than cluster model states for N-N processes. The usual cluster model representation omits configurations which emerge naturally in a molecular basis which contains the same number of spatial functions. The importance of the omitted states was demonstrated for a constituent quark model. The present work extends the study to the prototypical current quark model, namely the MIT bag. In order to test the expansion for short-range N-N interactions, the eigenstates and eigenenergies of six quarks in a spherical bag, including one-gluon exchange, are calculated. The lowest eigenenergies are lowered significantly with respect to the usual cluster model. This reaffirms the importance of dynamics for obtaining the needed short-range repulsion
International Nuclear Information System (INIS)
Hasenfratz, P.; Kuti, J.
1978-01-01
The quark bag model is reviewed here with particular emphasis on spectroscopic applications and the discussion of exotic objects as baryonium, gluonium, and the quark phase of matter. The physical vacuum is pictured in the model as a two-phase medium. In normal phase of the vacuum, outside hadrons, the propagation of quark and gluon fields is forbidden. When small bubbles in a second phase are created in the medium of the normal phase with a characteristic size of one fermi, the hadron constituent fields may propagate inside the bubbles in normal manner. The bubble (bag) is stabilized against the pressure of the confined hadron constituent fields by vacuum pressure and surface tension. Inside the bag the colored quarks and gluons are governed by the equations of quantum chromodynamics. (Auth.)
Remarks on electromagnetic form factors of hadrons in the quark model
International Nuclear Information System (INIS)
Vainshtein, A.I.; Zakharov, V.I.
1977-01-01
Relations between the transversal and longitudinal parts of elastic and quasielastic form factors are studied within the quark model. It is shown that for an even number of the constituent quarks the longitudinal part dominates while for an odd number the transversal part is the largest one. Consequences form this result are considered for deuteron form factor and for matrix elements of the electromagnetic transitions between π, rho, A 1 mesons
International Nuclear Information System (INIS)
Kramer, G.; Spiesberger, H.; Cape Town Univ., Rondebosch
2015-09-01
We present predictions for b-quark production in photoproduction and compare with experimental data from HERA. Our theoretical predictions are obtained at next-to-leading-order in the general-mass variable-flavor-number scheme, an approach which takes into account the finite mass of the b quarks. We use realistic evolved nonperturbative fragmentation functions obtained from fits to e + e - data. We find in general good agreement of data with both the GM-VFNS and the FFNS calculations, while the more precise ZEUS data seem to prefer the GM-VFNS predictions.
International Nuclear Information System (INIS)
Gasiorowicz, S.; Rosner, J.L.
1982-01-01
The quark model began as little more than a quantum-number counting device. After a brief period during which quarks only played a symmetry role, serious interest in quark dynamics developed. The marriage of the principle of local gauge invariance and quarks has been astonishingly productive. Although many questions still need to be be answered, there is little doubt that the strong, weak and electroweak interactions of matter are described by gauge theories of interactions of the quarks. This review is focussed on the successes
International Nuclear Information System (INIS)
Close, F.E.
1976-01-01
The studies of inelastic electron scattering at SLAC and of neutrino scattering at CERN have been widely interpreted as giving support to the idea that the nucleon is built from elementary constituents, called partons, and that these partons have the same quantum numbers as the quarks that are familiar in spectroscopy. In particular, a very simple regularity in the data, known as scale invariance or just 'scaling' was seen at least at moderate energies (2 2 > approximately 1 GeV) which is natural in the parton model. The data on e + e - annihilation also appear to be consistent with scaling when Esub(cm) approximately 5 GeV. These lectures are concerned with the scaling phenomena. One may expect the new hadronic degree of freedom to generate scaling violations in inelastic electron and neutrino scattering. These are mentioned briefly in these lectures. (Auth.)
S, P, D, F, G-waves KN phase shifts in a constituent quark model with a spin-orbit interaction
International Nuclear Information System (INIS)
Lemaire, S.; Labarsouque, J.; Silvestre-Brac, B.
2002-01-01
The I=1 and I=0 kaon-nucleon s, p, d, f, g-waves phase shifts have been calculated in a nonrelativistic quark potential model using the resonating group method (RGM). The interquark potential includes gluon exchanges with a spin-orbit interaction. This force has been determined to reproduce as well as possible the meson and baryon spectra. The same force is employed for the cluster and intercluster dynamics and the relative KN wave-function is calculated without any approximation. While some channels are correctly described, the theory is still unable to explain others
Static quark-antiquark potential
International Nuclear Information System (INIS)
Deo, B.B.; Barik, B.K.
1983-01-01
A heavy-quark--antiquark potential is suggested which connects asymptotic freedom and quark confinement in a unified manner by formal methods of field theory using some plausible assumptions. The potential has only one additional adjustable parameter B which is proportional to (M/sub q//m/sub q/), where M/sub q/ and m/sub q/ are the constituent and current quark masses, respectively
Directory of Open Access Journals (Sweden)
Wonhoon Lee
Full Text Available Bemisia tabaci (Hemiptera: Aleyrodidae is one of the most important insect pests in the world. In the present study, the taxonomic status of B. tabaci and the number of species composing the B. tabaci complex were determined based on 1059 COI sequences of B. tabaci and 509 COI sequences of 153 hemipteran species. The genetic divergence within B. tabaci was conspicuously higher (on average, 11.1% than interspecific genetic divergence within the respective genera of the 153 species (on average, 6.5%. This result indicates that B. tabaci is composed of multiple species that may belong to different genera or subfamilies. A phylogenetic tree constructed based on 212 COI sequences without duplications revealed that the B. tabaci complex is composed of a total of 31 putative species, including a new species, JpL. However, genetic divergence within six species (Asia II 1, Asia II 7, Australia, Mediterranean, New World, and Sub Saharan Africa 1 was higher than 3.5%, which has been used as a threshold of species boundaries within the B. tabaci complex. These results suggest that it is necessary to increase the threshold for species boundaries up to 4% to distinguish the constituent species in the B. tabaci complex.
Meson Spectroscopy in the Light Quark Sector
De Vita, R.
2014-03-01
Understanding the hadron spectrum is one of the fundamental issues in modern particle physics. We know that existing hadron configurations include baryons, made of three quarks, and mesons, made of quark-antiquark pairs. However most of the mass of the hadrons is not due to the mass of these elementary constituents but to their binding force. Studying the hadron spectrum is therefore a tool to understand one of the fundamental forces in nature, the strong force, and Quantum Chromo Dynamics (QCD), the theory that describes it. This investigation can provide an answer to fundamental questions as what is the origin of the mass of hadrons, what is the origin of quark confinement, what are the relevant degrees of freedom to describe these complex systems and how the transition between the elementary constituents, quarks and gluons, and baryons and mesons occurs. In this field a key tool is given by meson spectroscopy. Mesons, being made by a quark and an anti-quark, are the simplest quark bound system and therefore the ideal benchmark to study the interaction between quarks and understand what the role of gluons is. In this investigation, it is fundamental to precisely determine the spectrum and properties of mesons but also to search for possible unconventional states beyond the qbar q configuration as tetraquarks (qqoverline{qq}), hybrids (qbar qg) and glueballs. These states can be distinguished unambiguously from regular mesons when they have exotic quantum numbers, i.e. combinations of total angular momentum, spin and parity that are not allowed for qbar q states. These are called exotic quantum numbers and the corresponding states are referred to as exotics. The study of the meson spectrum and the search for exotics is among the goals of several experiments in the world that exploit different reaction processes, as e+e- annihilation, pbar p annihilation, pion scattering, proton-proton scattering and photo-production, to produce meson states. This intense effort is
Abbaspour, S.; Mohammad Moosavi Nejad, S.
2018-05-01
Charged Higgs bosons are predicted by some non-minimal Higgs scenarios, such as models containing Higgs triplets and two-Higgs-doublet models, so that the experimental observation of these bosons would indicate physics beyond the Standard Model. In the present work, we introduce a channel to indirect search for the charged Higgses through the hadronic decay of polarized top quarks where a top quark decays into a charged Higgs H+ and a bottom-flavored meson B via the hadronization process of the produced bottom quark, t (↑) →H+ + b (→ B + jet). To obtain the energy spectrum of produced B-mesons we present, for the first time, an analytical expression for the O (αs) corrections to the differential decay width of the process t →H+ b in presence of a massive b-quark in the General-Mass Variable-Flavor-Number (GM-VFN) scheme. We find that the most reliable predictions for the B-hadron energy spectrum are made in the GM-VFN scheme, specifically, when the Type-II 2HDM scenario is concerned.
International Nuclear Information System (INIS)
Volkov, D.V.; Zheltukhin, A.A.; Pashnev, A.I.
1975-01-01
As it has shown, the study of vacuum transitions in dual models makes it possible to establish certain relations between duality, on the one hand, and the quark structure of resonances and the internal symmetries, on the other. In the case of Veneziano model the corresponding quark structure of resonances is determined by the infinity number of quarks of increasing mass. The intercents of the main trajectory and all adopted trajectories are additive with respect to squares of mass-forming quarks. The latter circumstance results in a number of important consequences: the presence of quadratic mass formulas for resonance states; the exact SU(infinity)-symmetry for the three-resonance coupling constants; the validity of Adler's self-consistency principle for external particles composed of different quarks and anti-quarks, etc
Quasinuclear colored quark model for hadrons
International Nuclear Information System (INIS)
Lipkin, H.J.
1978-09-01
Lectures are presented in which a quasinuclear constituent quark model in which constituent quarks are assumed to be made of constituent interacting with a two-body color-exchange logarithmic potential is considered. The color degree of freedom is discussed in detail. Some properties of the logarithmic potential and the definition of the quasinuclear model and its validity, and a comparison of some of its predictions with experiment are described. 31 references
The quark revolution and the ZGS - new quarks physics since the ZGS
International Nuclear Information System (INIS)
Lipkin, H.J.
1994-01-01
Overwhelming experimental evidence for quarks as real physical constituents of hadrons along with the QCD analogs of the Balmer Formula, Bohr Atom and Schroedinger Equation already existed in 1966 but was dismissed as heresy. ZGS experiments played an important role in the quark revolution. This role is briefly reviewed and subsequent progress in quark physics is described
Laenen, E.
2012-01-01
The theoretical aspects of a number of top quark properties such as its mass and its couplings are reviewed. Essential aspects in the theoretical description of top quark production, singly, in pairs and in association, as well as its decay related to spin and angular correlations are discussed.
Quark Condensate in the Strange Matter
Institute of Scientific and Technical Information of China (English)
LU Chang-Fang; LU" Xiao-Fu
2003-01-01
In a nonlinear chiral SU(3) framework, we investigate the quark condensate in the strange matter including N, Σ, Ξ, and Λ, making use of chiral symmetry spontaneous breaking Lagrangian and mean-field approximation. The results show that the chiral symmetry is restored partially when the strange matter density increases and that 〈π→2〉 plays a very important role in the strange matter which may approach the constituents of the neutron stars. In addition, we can find that the strange matter density where the π-condensate emerges leads to the ratio of the nucleon number to baryon number.
International Nuclear Information System (INIS)
Rho, Mannque.
1980-04-01
The present status of our understanding of the physics of hadronic (nuclear or neutron) matter under extreme conditions, in particular at high densities is discussed. This is a problem which challenges three disciplines of physics: nuclear physics, astrophysics and particle physics. It is generally believed that we now have a correct and perhaps ultimate theory of the strong interactions, namely quantum chromodynamics (QCD). The constituents of this theory are quarks and gluons, so highly dense matters should be describable in terms of these constituents alone. This is a question that addresses directly to the phenomenon of quark confinement, one of the least understood aspects in particle physics. For nuclear physics, the possibility of a phase change between nuclear matter and quark matter introduces entirely new degrees of freedom in the description of nuclei and will bring perhaps a deeper understanding of nuclear dynamics. In astrophysics, the properties of neutron stars will be properly understood only when the equation of state of 'neutron' matter at densities exceeding that of nuclear matter can be realiably calculated. Most fascinating is the possibility of quark stars existing in nature, not entirely an absurd idea. Finally the quark matter - nuclear matter phase transition must have occured in the early stage of universe when matter expanded from high temperature and density; this could be an essential ingredient in the big-bang cosmology
International Nuclear Information System (INIS)
Kerman, A.K.
1981-01-01
This short talk gives some very general comments on what I see as the impact on nuclear physics of the last ten years' developments in the picture of the nucleon and the hadron. On the other hand there may also be some nuclear physics lessons - lessons we've learned by trying to deal with the multi-fermion system over a long period - and I will discuss what those lessons might be for the problem at hand, hadron phy-physics up to 31 GeV. After that I will discuss a number of implications of quarks for low energy physics
Heavy quark production processes in QCD
International Nuclear Information System (INIS)
Brodsky, S.J.; Gunion, J.F.
1984-12-01
We have identified two novel effects in QCD, each of which acts to enhance the production of heavy quark and supersymmetric particles beyond what is conventionally expected from gluon fusion. Both effects are present in QED, but are compounded in QCD because of the increased number of diagrams and the much larger coupling constant. The intrinsic charm quark distribution in the nucleon could account for the observed enhancements of the charm structure function at large x and features of the charm production data but this mechanism is relatively suppressed for heavier systems. Prebinding distortion of the fusion cross section is, however, likely to be significant for the production at low p/sub T/ of all particles containing heavy colored constituents. At this stage the QCD calculations are highly model dependent although they agree with the general properties which can be inferred from the operator product expansion in the heavy quark mass. Much more theoretical analysis of these effects is clearly needed. It is also clear that much more experimental work is necessary to extend and confirm the reported anomalous heavy quark signals. 22 references
International Nuclear Information System (INIS)
Greenberg, O.W.
1982-01-01
Quarks as fundamental constituents of hadrons play a central role in elementary particle physics. We give an annotated bibliography of references to quarks and related topics in elementary particle physics, as well as to the role of quarks in areas outside elementary particle physics, such as nuclear physics, and astrophysics and cosmology. We label references E (elementary), I (intermediate), and A (advanced) to guide the reader. Articles selected for incorporation in a reprint volume (to be published separately by the American Association of Physics Teachers) are indicated by an an asterisk. A short list of particularly helpful elementary and intermediate references is indicated by a star
The calculation of multiquark hadrons by the quark model baryon, meson and multiquark states
International Nuclear Information System (INIS)
Takeuchi, Sachiko; Takizawa, Makoto; Yasui, Shigehiro
2011-01-01
The 1st new hadron summer school related with the new science field, 'the comprehensive research of new hadron states searched by variable flavor number scheme', was held on August 18-20, 2010. This report is one of the 'quark model' lectures. The chapter 1 describes following problems: 1. The background and the significance as a phenomenological theory of the constituent quark model. 2. The introduction of the quark model. 3. The summary of the properties of hadrons in which the quark model can apply to three quarks (qqq) and, one quark and antiquark (q - q) configurations, but is difficult to apply to some configurations. 4. A brief summary of exotic hadrons and recent problems. In chapter 2, the introduction and some exercises of the stochastic variational method are reported as a technique of solving spatial part of multiquark states. In the chapter 3, spins and color parts in multiquark states are calculated. The group theory is applied to calculate the eigenvalues of the Casimir operators of SU(2), SU(3) and SU(6). In the problems of being unable to apply Casimir operators, the direct matrix diagonalization method, m-scheme, is employed for interacting quarks and for the interaction involving quark mass. To find the attractive interaction in tetraquark (QQqq-bar) state is given as an exercise problem. (Y. Kazumata)
Additivity of quark masses in gauge theories
International Nuclear Information System (INIS)
Scadron, M.D.
1987-01-01
It is shown that, in spite of the confinement of quarks in (color-singlet) hadrons, effective quark masses of all types (dynamically generated, constituent and current masses), naturally form hadron masses in an additivity fashion. For the purposes of brevity, the discussion is limited primarily to the nonstrange flavor sector
International Nuclear Information System (INIS)
Anon.
1987-01-01
Quarks are understood to interact through the 'colour' force, carried by gluons. Under normal conditions these quarks are confined - frozen together in 'colourless' states such as protons, neutrons and other strongly interacting particles. However if the quarks are compressed tightly together and/or are 'heated' by increasing their energy, they should eventually break loose from their colour bonds to form a new kind of matter – the so-called quark-gluon plasma. Although QGP has not yet been synthesized in the Laboratory, it was most likely the stuff of the Universe 10 -5 second after the Big Bang. Thus the search for this 'new' matter is attracting a growing number of physicists, theorists and experimenters from both the particle physics and nuclear physics fields
International Nuclear Information System (INIS)
Joos, H.
1976-07-01
The main topics of these lectures are: phenomenological approach to quark confinement, standard Lagrangian of hadrondynamics, Lagrangian field theory and quark confinement, classical soliton solutions in a simple model, quantization of extended systems, colour charge screening and quantization on a lattice and remarks on applications. A survey of the scientific publications listed according to the topics until 26 March 1976 is supplemented. (BJ) [de
Quarks for hadrons and leptons
International Nuclear Information System (INIS)
Lopes, J.L.
1975-01-01
The simplest, naive, model for a unified description of leptons and hadrons consists in postulating, besides the usual quarks p, n, lambda a fourth quark, with very heavy mass and very high binding to pairs like anti p n and anti p lambda. In a SU(4) scheme the fourth quark has a quantum number charm which may be taken as proportional to the lepton number. Muons would be distinguished from electrons by the occurence of a lambda-quark instead of a n-quark in their structure. The forces among these quarks would have to be such as to give leptons an almost point-like structure at the experimentally known energies as well as absence of strong interactions at these energies. However, one would expect the display of strong interactions by leptons at extremely high energies [pt
Quark and pion effective couplings from polarization effects
Energy Technology Data Exchange (ETDEWEB)
Braghin, Fabio L. [Federal University of Goias, Instituto de Fisica, Goiania, GO (Brazil)
2016-05-15
A flavor SU(2) effective model for pions and quarks is derived by considering polarization effects departing from the usual quark-quark effective interaction induced by dressed gluon exchange, i.e. a global color model for QCD. For that, the quark field is decomposed into a component that yields light mesons and the quark-antiquark condensate, being integrated out by means of the auxiliary field method, and another component which yields constituent quarks, which is basically a background quark field. Within a long-wavelength and weak quark field expansion (or large quark effective mass expansion) of a quark determinant, the leading terms are found up to the second order in a zero-order derivative expansion, by neglecting vector mesons that are considerably heavier than the pion. Pions are considered in the structureless limit and, besides the chiral invariant terms that reproduce previously derived expressions, symmetry breaking terms are also presented. The leading chiral quark-quark effective couplings are also found corresponding to a NJL and a vector-NJL couplings. All the resulting effective coupling constants and parameters are expressed in terms of the current and constituent quark masses and of the coupling g. (orig.)
Bootstrapping quarks and gluons
Energy Technology Data Exchange (ETDEWEB)
Chew, G.F.
1979-04-01
Dual topological unitarization (DTU) - the approach to S-matrix causality and unitarity through combinatorial topology - is reviewed. Amplitudes associated with triangulated spheres are shown to constitute the core of particle physics. Each sphere is covered by triangulated disc faces corresponding to hadrons. The leading current candidate for the hadron-face triangulation pattern employs 3-triangle basic subdiscs whose orientations correspond to baryon number and topological color. Additional peripheral triangles lie along the hadron-face perimeter. Certain combinations of peripheral triangles with a basic-disc triangle can be identified as quarks, the flavor of a quark corresponding to the orientation of its edges that lie on the hadron-face perimeter. Both baryon number and flavor are additively conserved. Quark helicity, which can be associated with triangle-interior orientation, is not uniformly conserved and interacts with particle momentum, whereas flavor does not. Three different colors attach to the 3 quarks associated with a single basic subdisc, but there is no additive physical conservation law associated with color. There is interplay between color and quark helicity. In hadron faces with more than one basic subdisc, there may occur pairs of adjacent flavorless but colored triangles with net helicity +-1 that are identifiable as gluons. Broken symmetry is an automatic feature of the bootstrap. T, C and P symmetries, as well as up-down flavor symmetry, persist on all orientable surfaces.
Bootstrapping quarks and gluons
International Nuclear Information System (INIS)
Chew, G.F.
1979-04-01
Dual topological unitarization (DTU) - the approach to S-matrix causality and unitarity through combinatorial topology - is reviewed. Amplitudes associated with triangulated spheres are shown to constitute the core of particle physics. Each sphere is covered by triangulated disc faces corresponding to hadrons. The leading current candidate for the hadron-face triangulation pattern employs 3-triangle basic subdiscs whose orientations correspond to baryon number and topological color. Additional peripheral triangles lie along the hadron-face perimeter. Certain combinations of peripheral triangles with a basic-disc triangle can be identified as quarks, the flavor of a quark corresponding to the orientation of its edges that lie on the hadron-face perimeter. Both baryon number and flavor are additively conserved. Quark helicity, which can be associated with triangle-interior orientation, is not uniformly conserved and interacts with particle momentum, whereas flavor does not. Three different colors attach to the 3 quarks associated with a single basic subdisc, but there is no additive physical conservation law associated with color. There is interplay between color and quark helicity. In hadron faces with more than one basic subdisc, there may occur pairs of adjacent flavorless but colored triangles with net helicity +-1 that are identifiable as gluons. Broken symmetry is an automatic feature of the bootstrap. T, C and P symmetries, as well as up-down flavor symmetry, persist on all orientable surfaces
International Nuclear Information System (INIS)
Lipkin, H.J.
1980-09-01
Quark-lepton unification is examined without assuming higher symmetries on more general gauge theories. In particular, properties are sought which are generally attributed to SU(5) models which are already present without the assumption of SU(5)
Hydrodynamical model with massless constituents
International Nuclear Information System (INIS)
Chiu, C.B.; Wang, K.H.
1974-01-01
Within the constituent hydrodynamical model, it is shown that the total number of constituents is conserved, if these constituents are massless and satisfy the Fermi-Dirac distribution. A simple scheme for the transition from the constituent-phase to the hadron-phase is suggested, and the hadron inclusive momentum spectra are presented for this case. This phase transition scheme predicts the average transverse momentum of meson resonances which is compatible with the data. (U.S.)
Quark chemistry: charmonium molecules
International Nuclear Information System (INIS)
De Rujula, A.; Jaffe, R.L.
1977-01-01
The theoretical and experimental evidence for two quark-two antiquark hadrons is reviewed. Concentration is placed on predictions for S-wave ''charmonium molecules,'' built of a c anti c charmonium pair and a light quark-antiquark pair. Their spectrum and quantum numbers are predicted and an estimate of their decay couplings and their prediction in monochromatic pion decays from charmonium resonances produced in e + e - -annihilation is given. Some S-wave charmonium resonances should be detectable in these decays, but typical branching ratios are only at the 1% level. 19 references
International Nuclear Information System (INIS)
Anon.
1981-01-01
In spite of (or perhaps because of) the present doctrine of total quark confinement held by the majority of particle theorists, experimental searches for free fractional charge and other anomalous stable particles in ordinary matter have been increasing in number during recent years, using a range of techniques of increasing sophistication and sensitivity. As a result, researchers in this area had a conference to themselves in June. About 40 participants and 150 observers gathered at San Francisco State University to report progress and discuss future plans, with representatives present from almost every group involved in quark searches
Indian Academy of Sciences (India)
2012-10-04
Oct 4, 2012 ... The theoretical aspects of a number of top quark properties such as ... to the quadratic divergences of the Higgs self-energy, while yet, ..... given in the literature, each with the aim of recovering a well-behaved expansion in αs.
International Nuclear Information System (INIS)
Abelev, B.I.; Adams, J.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson, B.D.; Anderson, M.; Arkhipkin, D.; Averichev, G.S.; Bai, Y.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellingeri-Laurikainen, A.; Bellwied, R.; Benedosso, F.; Bhardwaj, S.; Bhasin, A.; Bhati, A.K.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L.C.; Blyth, S.-L.; Bonner, B.E.; Botje, M.; Bouchet, J.; Brandin, A.V.; Bravar, A.; Bystersky, M.; Cadman, R.V.; Cai, X.Z.; Caines, H.; Calderon de la Barca Sanchez, M.; Castillo, J.; Catu, O.; Cebra, D.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen, H.F.; Chen, J.H.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cosentino, M.R.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; Daugherity, M.; de Moura, M.M.; Dedovich, T.G.; DePhillips, M.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Djawotho, P.; Dogra, S.M.; Dong, W.J.; Dong, X.; Draper, J.E.; Du, F.; Dunin, V.B.; Dunlop, J.C.; Dutta Mazumdar, M.R.; Eckardt, V.; Edwards, W.R.; Efimov, L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Fatemi, R.; Fedorisin, J.; Filimonov, K.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Fu, J.; Gagliardi, C.A.; Gaillard, L.; Ganti, M.S.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.S.; Gorbunov, Y.G.; Gos, H.; Grebenyuk, O.; Grosnick, D.; Guertin, S.M.; Guimaraes, K.S.F.F.; Guo, Y.; Gupta, N.; Gutierrez, T.D.; Haag, B.; Hallman, T.J.; Hamed, A.; Harris, J.W.; He, W.; Heinz, M.; Henry, T.W.; Hepplemann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffman, A.M.; Hoffmann, G.W.; Horner, M.J.; Huang, H.Z.; Huang, S.L.; Hughes, E.W.; Humanic, T.J.; Igo, G.; Jacobs, P.; Jacobs, W.W.; Jakl, P.; Jia, F.; Jiang, H.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kang, K.; Kapitan, J.; Kaplan, M.; Keane, D.; Kechechyan, A.; Khodyrev, V.Yu.; Kim, B.C.; Kiryluk, J.; Kisiel, A.; Kislov, E.M.; Klein, S.R.; Kocoloski, A.; Koetke, D.D.
2007-01-01
We present STAR measurements of the azimuthal anisotropy parameter v 2 for pions, kaons, protons, Lambda, bar Lambda, Xi+bar Xi,and Omega + bar Omega, along with v 4 for pions, kaons, protons, and Lambda + bar Lambda at mid-rapidity for Au+Au collisions at sqrt sNN=62.4and 200 GeV. The v 2 (p T ) values for all hadron species at 62.4 GeV are similar to those observed in 130 and 200 GeV collisions. For observed kinematic ranges, v 2 values at 62.4, 130, and 200 GeV are as little as 10 percent-15 percent larger than those in Pb+Pb collisions at sqrt s NN=17.3 GeV. At intermediate transverse momentum (p T from 1.5-5 GeV/c),the 62.4 GeV v 2 (p T ) and v 4 (p T ) values are consistent with the quark-number scaling first observed at 200 GeV. A four-particle cumulant analysis is used to assess the non-flow contributions to pions and protons and some indications are found for a smaller non-flow contribution to protons than pions. Baryon v 2 is larger than anti-baryon v 2 at 62.4 and 200 GeV perhaps indicating either that the initial spatial net-baryon distribution is anisotropic, that the mechanism leading to transport of baryon number from beam- to mid-rapidity enhances v 2 , or that anti-baryon and baryon annihilation is larger in the in-plane direction
Nuclear matter from effective quark-quark interaction.
Baldo, M; Fukukawa, K
2014-12-12
We study neutron matter and symmetric nuclear matter with the quark-meson model for the two-nucleon interaction. The Bethe-Bruckner-Goldstone many-body theory is used to describe the correlations up to the three hole-line approximation with no extra parameters. At variance with other nonrelativistic realistic interactions, the three hole-line contribution turns out to be non-negligible and to have a substantial saturation effect. The saturation point of nuclear matter, the compressibility, the symmetry energy, and its slope are within the phenomenological constraints. Since the interaction also reproduces fairly well the properties of the three-nucleon system, these results indicate that the explicit introduction of the quark degrees of freedom within the considered constituent quark model is expected to reduce the role of three-body forces.
Quark matter and quark stars at finite temperature in Nambu-Jona-Lasinio model
Energy Technology Data Exchange (ETDEWEB)
Chu, Peng-Cheng; Wang, Bin; Dong, Yu-Min; Jia, Yu-Yue; Wang, Shu-Mei; Ma, Hong-Yang [Qingdao Technological University, School of Science, Qingdao (China); Li, Xiao-Hua [University of South China, School of Nuclear Science and Technology, Hengyang (China); University of South China, Cooperative Innovation Center for Nuclear Fuel Cycle Technology and Equipment, Hengyang (China)
2017-08-15
We extend the SU(3) Nambu-Jona-Lasinio (NJL) model to include two types of vector interaction. Using these two types of vector interaction in NJL model, we study the quark symmetry free energy in asymmetric quark matter, the constituent quark mass, the quark fraction, the equation of state (EOS) for β-equilibrium quark matter, the maximum mass of QSs at finite temperature, the maximum mass of proto-quark stars (PQSs) along the star evolution, and the effects of the vector interaction on the QCD phase diagram. We find that comparing zero temperature case, the values of quark matter symmetry free energy get larger with temperature increasing, which will reduce the difference between the fraction of u, d and s quarks and stiffen the EoS for β-equilibrium quark matter. In particular, our results indicate that the maximum masses of the quark stars increase with temperature because of the effects of the quark matter symmetry free energy, and we find that the heating(cooling) process for PQSs will increase (decrease) the maximum mass within NJL model. (orig.)
Soap opera: the sad tale of the quark
International Nuclear Information System (INIS)
Lipkin, H.
1984-01-01
The history of quark physics is briefly reviewed, followed by an introduction to quantum chromodynamics, leading terms, and the OZI rule. The basic physics of hadron structure as revealed by experiment is then discussed, followed by the models used to treat it. The two complementary models are the quasinuclear colored quark model and the quark-parton model. Another model for orthogonal physical properties is the bag model. Several applications of the constituent quark model are considered, including hadron masses, spin physics, and multiquark physics. The theoretical basis and phenomenology of the OZI rule forbids processes described by disconnected quark line diagrams
Semileptonic Decays of Heavy Omega Baryons in a Quark Model
International Nuclear Information System (INIS)
Muslema Pervin; Winston Roberts; Simon Capstick
2006-01-01
The semileptonic decays of (Omega) c and (Omega) b are treated in the framework of a constituent quark model developed in a previous paper on the semileptonic decays of heavy Λ baryons. Analytic results for the form factors for the decays to ground states and a number of excited states are evaluated. For (Omega) b to (Omega) c the form factors obtained are shown to satisfy the relations predicted at leading order in the heavy-quark effective theory at the non-recoil point. A modified fit of nonrelativistic and semirelativistic Hamiltonians generates configuration-mixed baryon wave functions from the known masses and the measured Λ c + → Λe + ν rate, with wave functions expanded in both harmonic oscillator and Sturmian bases. Decay rates of (Omega) b to pairs of ground and excited (Omega) c states related by heavy-quark symmetry calculated using these configuration-mixed wave functions are in the ratios expected from heavy-quark effective theory, to a good approximation. Our predictions for the semileptonic elastic branching fraction of (Omega) Q vary minimally within the models we use. We obtain an average value of (84 ± 2%) for the fraction of (Omega) c → Ξ (*) decays to ground states, and 91% for the fraction of (Omega) c → (Omega) (*) decays to the ground state (Omega). The elastic fraction of (Omega) b → (Omega) c ranges from about 50% calculated with the two harmonic-oscillator models, to about 67% calculated with the two Sturmian models
Constituent rearrangement model and large transverse momentum reactions
International Nuclear Information System (INIS)
Igarashi, Yuji; Imachi, Masahiro; Matsuoka, Takeo; Otsuki, Shoichiro; Sawada, Shoji.
1978-01-01
In this chapter, two models based on the constituent rearrangement picture for large p sub( t) phenomena are summarized. One is the quark-junction model, and the other is the correlating quark rearrangement model. Counting rules of the models apply to both two-body reactions and hadron productions. (author)
International Nuclear Information System (INIS)
Khoze, V.A.
1983-10-01
We discuss the results accumulated during the last five years in heavy quark physics and try to draw a simple general picture of the present situation. The survey is based on a unified point of view resulting from quantum chromodynamics. (orig.)
Quark-flavor mixing and the nucleon strangeness form factors
International Nuclear Information System (INIS)
Ito, H.
1995-01-01
We have calculated the strangeness form factors of the nucleon G E s (Q), G M s (Q) and G A s (Q) and the electromagnetic form factors G E N (Q) as well, by using a relativistic constituent quark model of the nucleon wave function on the light-cone. Octet of Goldstone bosons (π, K, η) are assumed to induce the SU flavor mixing among the light constituent quarks; d-→K+s →d for example, and this mechanism induces the strangeness content in the nucleon. To calculate the meson-loop corrections to the electroweak couplings of constituent quarks, we have employed two models of the quark-meson vertex; (1) composite model of the Goldstone bosons (2) and (3) chiral quark Lagrangian. The loop momenta are regulated in a gauge-invariant way for both models
Quark-lepton unification and proton decay
International Nuclear Information System (INIS)
Pati, J.C.; Salam, A.
1980-05-01
Complexions for proton decay arising within a maximal symmetry for quark-lepton unification, which leads to spontaneous rather than intrinsic violations of B, L and F are considered. Four major modes satisfying δB=-1 and δF=0, -2, -4 and -6 are noted. It is stressed that some of these modes can coexist in accord with allowed solutions for renormalization group equations for coupling constants for a class of unifying symmetries. None of these remarks is dependent on the nature of quark charges. It is noted that if quarks and leptons are made of constituent preons, the preon binding is likely to be magnetic. (author)
Quarks as quasiparticles of bound states
International Nuclear Information System (INIS)
Tyapkin, A.A.
1977-01-01
Interpretation of quarks as strongly bound subsystems of the baryon structure, being in various states with integer the quantum numbers Q and B, is considered. Three original quark states, distinguished by Q, B, and J, are unambiguously determined from the condition that the quarks have the corresponding fractional quantum numbers while the integer quantum numbers for the whole system are known. With this in view the new quantum number ''colour'' is interpreted as a quantity, specifying the appearance of the subsystems in various eigen-states. Basing on the generalized Sakata model, the self-consistency of change of the colour states in the three-quark system is explained
Meson-Meson molecules and compact four-quark states
International Nuclear Information System (INIS)
Vijande, J.; Valcarce, A.
2010-01-01
The physics of charm has become one of the best laboratories exposing the limitations of the naive constituent quark model and also giving hints into a more mature description of meson spectroscopy, beyond the simple quark-antiquark configurations. In this talk we review some recent studies of multiquark components in the charm sector and discuss in particular exotic and non-exotic four-quark systems.
International Nuclear Information System (INIS)
Maki, Tuula; Helsinki Inst. of Phys.; Helsinki U. of Tech.
2008-01-01
The top quark is the heaviest elementary particle. Its mass is one of the fundamental parameters of the standard model of particle physics, and an important input to precision electroweak tests. This thesis describes three measurements of the top-quark mass in the dilepton decay channel. The dilepton events have two neutrinos in the final state; neutrinos are weakly interacting particles that cannot be detected with a multipurpose experiment. Therefore, the signal of dilepton events consists of a large amount of missing energy and momentum carried off by the neutrinos. The top-quark mass is reconstructed for each event by assuming an additional constraint from a top mass independent distribution. Template distributions are constructed from simulated samples of signal and background events, and parameterized to form continuous probability density functions. The final top-quark mass is derived using a likelihood fit to compare the reconstructed top mass distribution from data to the parameterized templates. One of the analyses uses a novel technique to add top mass information from the observed number of events by including a cross-section-constraint in the likelihood function. All measurements use data samples collected by the CDF II detector
International Nuclear Information System (INIS)
Jackson, T.L.
1976-01-01
The infrared limit in asymptotically free non-abelian gauge theories using recently developed non-perturbative methods which allow derivation of zero momentum theorems for Green's functions and vertices is described. These low-energy theorems are compared to the infrared behavior predicted from the renormalization group equation when the existence of an infrared fixed point is assumed. A set of objects is exhibited whose low energy theorems violate the scaling behavior predicted by the renormalization group. This shows that the assumed fixed point cannot exist and that in the Landau gauge the effective charge becomes infinite in the infrared. Qualitatively this implies that as an attempt is made to separate elementary quanta the interaction between the quanta becomes arbitrarily strong. This indicates at least that the theories studied are capable of color confinement. Results are true only for theories with large numbers of quarks. This opens the possibility that large numbers of quarks are actually necessary for confinement
The conventional quark picture
International Nuclear Information System (INIS)
Dalitz, R.H.
1976-01-01
For baryons, mesons and deep inelastic phenomena the ideas and the problems of the conventional quark picture are pointed out. All observed baryons fit in three SU(3)-multiplets which cluster into larger SU(6)-multiplets. No mesons are known which have quantum numbers inconsistent with belonging to a SU(3) nonet or octet. The deep inelastic phenomena are described in terms of six structure functions of the proton. (BJ) [de
International Nuclear Information System (INIS)
Nambu, J.
1978-01-01
Three quark models of hadron structure, which suggest an explanation of quarks confinement mechanism in hadrons are considered. Quark classifications, quark flawors and colours, symmetry model of hadron structure based on the colour theory of strong interaction are discussed. Diagrams of colour combinations of quarks and antiquarks, exchange of gluons, binding quarks in hadron. Quark confinement models based on the field theory, string model rotating and bag model are discussed. Diagrams of the colour charge distribution explaining the phenomena of infrared ''slavery'' and ultraviolet ''freedom'' are given. The models considered explain but some quark properties, creating prerequisites for the development of the consequent theory of hadron structure
Prospects of detecting baryon and quark superfluidity from cooling neutron stars
Page; Prakash; Lattimer; Steiner
2000-09-04
Baryon and quark superfluidity in the cooling of neutron stars are investigated. Future observations will allow us to constrain combinations of the neutron or Lambda-hyperon pairing gaps and the star's mass. However, in a hybrid star with a mixed phase of hadrons and quarks, quark gaps larger than a few tenths of an MeV render quark matter virtually invisible for cooling. If the quark gap is smaller, quark superfluidity could be important, but its effects will be nearly impossible to distinguish from those of other baryonic constituents.
Energy Technology Data Exchange (ETDEWEB)
Wicke, Daniel; /Wuppertal U., Dept. Math.
2009-08-01
Tevatron experiments CDF and D0 and was the last of the quarks to be discovered. As the partner of the bottom quark the top quark is expected to have quantum numbers identical to that of the other known up-type quarks. Only the mass is a free parameter. We now know that it is more than 30 times heavier than the next heaviest quark, the bottom quark. Thus, within the Standard Model all production and decay properties are fully defined. Having the complete set of quarks further allows to verify constraints that the Standard Model puts on the sum of all quarks or particles. This alone is reason enough to experimentally study the top quark properties. The high value of the top quark mass and its closeness to the electroweak scale has inspired people to speculate that the top quark could have a special role in the electroweak symmetry breaking. Confirming the expected properties of the top quark experimentally establishes the top quark as we expect it to be. Any deviation from the expectations gives hints to new physics that may help to solve the outstanding questions. In this review the recent results on top quark properties obtained by the Tevatron experiments CDF and D0 are summarized. At the advent of the LHC special emphasis is given to the basic measurement methods and the dominating systematic uncertainties. After a short introduction to the Standard Model and the experimental environment in the remainder of this chapter, Chapter 2 describes the current status of top quark mass measurements. Then measurments of interaction properties are described in Chapter 3. Finally, Chapter 4 deals with analyses that consider hypothetical particles beyond the Standard Model in the observed events.
International Nuclear Information System (INIS)
Wicke, Daniel
2009-01-01
Tevatron experiments CDF and D0 and was the last of the quarks to be discovered. As the partner of the bottom quark the top quark is expected to have quantum numbers identical to that of the other known up-type quarks. Only the mass is a free parameter. We now know that it is more than 30 times heavier than the next heaviest quark, the bottom quark. Thus, within the Standard Model all production and decay properties are fully defined. Having the complete set of quarks further allows to verify constraints that the Standard Model puts on the sum of all quarks or particles. This alone is reason enough to experimentally study the top quark properties. The high value of the top quark mass and its closeness to the electroweak scale has inspired people to speculate that the top quark could have a special role in the electroweak symmetry breaking. Confirming the expected properties of the top quark experimentally establishes the top quark as we expect it to be. Any deviation from the expectations gives hints to new physics that may help to solve the outstanding questions. In this review the recent results on top quark properties obtained by the Tevatron experiments CDF and D0 are summarized. At the advent of the LHC special emphasis is given to the basic measurement methods and the dominating systematic uncertainties. After a short introduction to the Standard Model and the experimental environment in the remainder of this chapter, Chapter 2 describes the current status of top quark mass measurements. Then measurments of interaction properties are described in Chapter 3. Finally, Chapter 4 deals with analyses that consider hypothetical particles beyond the Standard Model in the observed events.
Two-Quark Condensate Changes with Quark Current Mass
International Nuclear Information System (INIS)
Lu Changfang; Lue Xiaofu; Wu Xiaohua; Zhan Yongxin
2009-01-01
Using the Schwinger-Dyson equation and perturbation theory, we calculate the two-quark condensates for the light quarks u, d, strange quark s and a heavy quark c with their current masses respectively. The results show that the two-quark condensate will decrease when the quark mass increases, which hints the chiral symmetry may be restored for the heavy quarks.
Thermal recombination: Beyond the valence quark approximation
Energy Technology Data Exchange (ETDEWEB)
Mueller, B. [Department of Physics, Duke University, Durham, NC 27708 (United States); Fries, R.J. [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States)]. E-mail: fries@physics.umn.edu; Bass, S.A. [Department of Physics, Duke University, Durham, NC 27708 (United States); RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973 (United States)
2005-07-07
Quark counting rules derived from recombination models agree well with data on hadron production at intermediate transverse momenta in relativistic heavy-ion collisions. They convey a simple picture of hadrons consisting only of valence quarks. We discuss the inclusion of higher Fock states that add sea quarks and gluons to the hadron structure. We show that, when recombination occurs from a thermal medium, hadron spectra remain unaffected by the inclusion of higher Fock states. However, the quark number scaling for elliptic flow is somewhat affected. We discuss the implications for our understanding of data from the Relativistic Heavy Ion Collider.
Heavy quark production in quantum chromodynamics
International Nuclear Information System (INIS)
Brodsky, S.J.
1986-09-01
For very heavy quark masses, the inclusive hadronic production of hadron pairs containing heavy quarks is predicted to be governed by QCD fusion subprocesses. For intermediate mass scales other QCD mechanisms can be important including higher-twist intrinsic contributions and low relative velocity enchancements, possibly accounting for the anomalies observed in charm hadroproduction, such as the nuclear number dependence, the longitudinal momentum distributions, and beam flavor dependence. We also discuss scaling laws for exclusive processes involving heavy quarks and diffractive excitation into heavy quark systems
International Nuclear Information System (INIS)
Granier de Cassagnac, R.
2010-01-01
The quark-gluon plasma (QGP) is a state of matter in which the universe was expected to be a few micro-seconds after the big-bang. Violent collisions of heavy ions are supposed to re-create this state in particle accelerators. Numerous signatures of this fugacious state have already been observed at the RHIC (relativistic heavy ion collider). The first evidence of the violence of collisions is the number of generated particles: about 6000 per collision, mostly hadrons. This figure seems high but in fact is less than theoretically expected and is the first sign of the formation of a QGP that saturates the density of gluons. Another sign, observed at the RHIC is the damping of the particle jets that are produced in the collision. This damping is consistent with the crossing of a medium whose density is so high that it can not be made of hadrons but of partons. In the RHIC experiments the collective behaviour of quarks and gluons shows that they are strongly interacting with one another. This fact supports the idea that the QGP is more a perfect liquid rather than an ideal gas in which quarks and gluons move freely. (A.C.)
Instanton vacuum at finite density of quark matter
International Nuclear Information System (INIS)
Molodtsov, S.V.; Zinovjev, G.M.
2002-01-01
We study light quark interactions in the instanton liquid at finite quark/baryon number density analyzing chiral and diquark condensates and investigate the behaviors of quark dynamical mass and both condensates together with instanton liquid density as a function of quark chemical potential. We conclude the quark impact (estimated in the tadpole approximation) on the instanton liquid could shift color superconducting phase transition to higher values of the chemical potential bringing critical quark matter density to the values essentially higher than conventional nuclear one
Who needs more than four quarks
International Nuclear Information System (INIS)
Montonen, C.; Roos, M.
1976-09-01
The authors argue that there are no compelling reasons, experimental or theoretical, for an enlarged quark sector. They show that there is a large number of acceptable anomaly-free models with the usual four-quark-sector and one or two heavy charged leptons. (L.M.K.)
Constituent models and large transverse momentum reactions
International Nuclear Information System (INIS)
Brodsky, S.J.
1975-01-01
The discussion of constituent models and large transverse momentum reactions includes the structure of hard scattering models, dimensional counting rules for large transverse momentum reactions, dimensional counting and exclusive processes, the deuteron form factor, applications to inclusive reactions, predictions for meson and photon beams, the charge-cubed test for the e/sup +-/p → e/sup +-/γX asymmetry, the quasi-elastic peak in inclusive hadronic reactions, correlations, and the multiplicity bump at large transverse momentum. Also covered are the partition method for bound state calculations, proofs of dimensional counting, minimal neutralization and quark--quark scattering, the development of the constituent interchange model, and the A dependence of high transverse momentum reactions
Effective field theories of baryons and mesons, or, what do quarks do?
International Nuclear Information System (INIS)
Keaton, G.L.
1995-01-01
This thesis is an attempt to understand the properties of the protons, pions and other hadrons in terms of their fundamental building blocks. In the first chapter the author reviews several of the approaches that have already been developed. The Nambu-Jona-Lasinio model offers the classic example of a derivation of meson properties from a quark Lagrangian. The chiral quark model encodes much of the intuition acquired in recent decades. The author also discusses the non-linear sigma model, the Skyrme model, and the constituent quark model, which is one of the oldest and most successful models. In the constituent quark model, the constituent quark appears to be different from the current quark that appears in the fundamental QCD Lagrangian. Recently it was proposed that the constituent quark is a topological soliton. In chapter 2 the author investigates this soliton, calculating its mass, radius, magnetic moment, color magnetic moment, and spin structure function. Within the approximations used, the magnetic moments and spin structure function cannot simultaneously be made to agree with the constituent quark model. In chapter 3 the author uses a different plan of attack. Rather than trying to model the constituents of the baryon, he begins with an effective field theory of baryons and mesons, with couplings and masses that are simply determined phenomenologically. Meson loop corrections to baryon axial currents are then computed in the 1/N expansion. It is already known that the one-loop corrections are suppressed by a factor 1/N; here it is shown that the two-loop corrections are suppressed by 1/N 2 . To leading order, these corrections are exactly the same as would be calculated in the constituent quark model. This method therefore offers a different approach to the constituent quark
Measurements and searches with top quarks
International Nuclear Information System (INIS)
Peters, Reinhild Yvonne
2008-01-01
to search for charged or neutral Higgs bosons. Depending on its mass, the charged Higgs boson is expected to decay either into top quarks or be the decay product of a top quark. For masses below the top quark mass, the top decay into a charged Higgs boson and a b quark can occur at a certain rate, additionally to the decays into W bosons and a b quark. The different decays of W and charged Higgs bosons can lead to deviations of the observed final number of events in certain final states with respect to the Standard Model expectation. A global search for charged Higgs bosons in top quark pair events is presented in this thesis, resulting in the most stringent limits to-date. Besides the decay of top quarks into charged Higgs or W bosons, new physics can also show up in the quark part of the decay. While in the Standard Model the top quark decays with a rate of about 100% into a W boson and a b quark, there are models where the top quark can decay into a W boson and a non-b quark. The ratio of branching fractions in which the top quark decays into a b quark over the branching fractions in which the top quark decays into all quarks is measured as part of this thesis, yielding the most precise measurement today. Furthermore, the Standard Model top quark pair production cross section is essential to be known precisely since the top quark pair production is the main background for t(bar t)H production and many other Higgs and beyond the Standard Model searches. However, not only the search or the test of the Standard Model itself make the precise measurement of the top quark pair production cross section interesting. As the cross section is calculated with high accuracy in perturbative QCD, a comparison of the measurement to the theory expectation yields the possibility to extract the top quark mass from the cross section measurement. Although many dedicated techniques exist to measure the top quark mass, the extraction from the cross section represents an important
International Nuclear Information System (INIS)
Bjorken, J.D.
1985-12-01
Even if stable hadrons with fractional charge do not exist, most of the criteria of observability used for ordinary elementary particles apply in principle to quarks as well. This is especially true in a simplified world containing only hadrons made of top quarks and gluons. In the real world containing light quarks, essential complications do occur, but most of the conclusions survive
International Nuclear Information System (INIS)
Jacob, Maurice
1988-01-01
The 'Quark Matter' Conference caters for physicists studying nuclear matter under extreme conditions. The hope is that relativistic (high energy) heavy ion collisions allow formation of the long-awaited quark-gluon plasma, where the inter-quark 'colour' force is no longer confined inside nucleon-like dimensions
Pseudoscaler meson masses in the quark model
International Nuclear Information System (INIS)
Karl, G.
1976-10-01
Pseudoscaler meson masses and sum rules are compared in two different limits of a quark model with 4 quarks. The conventional limit corresponds to a heavy c anti c state and generalizes ideal mixing in a nonet. The second limit corresponds to a missing SU 4 unitary singlet and appears more relevant to the masses of π, K, eta, eta'. If SU 3 is broken only by the mass difference between the strange and nonstrange quarks, the physical masses imply that the u anti u, d anti d and s anti s pairs account only for 33% of the composition of the eta'(960), while for the eta(548) this fraction is 86%. If some of the remaining matter is in the form of the constituents of J/psi, the relative proportion of the relative decays J/psi → eta γ vs J/psi → etaγ is accounted for in satisfactory agreement with experiment. (author)
Workshop: Waiting for the top quark
International Nuclear Information System (INIS)
Anon.
1991-01-01
The world of elementary particle physics is eagerly waiting for the top quark, probably the final element of the 'periodic table' of elementary particle constituents. This table consists of two families of weakly interacting particles (leptons) - one series carrying electric charge; the other being electrically neutral - together with a family of quarks carrying electric charge 2/3 (up, charm, top) and a family of charge -1/3 quarks (down, strange, beauty). It was then not surprising that the 1990 Theory Workshop at the DESY Laboratory in Hamburg in October, devoted this time to 'top physics', attracted some 200 physicists, substantially more than previous workshops in the series
Quark Matter May Not Be Strange.
Holdom, Bob; Ren, Jing; Zhang, Chen
2018-06-01
If quark matter is energetically favored over nuclear matter at zero temperature and pressure, then it has long been expected to take the form of strange quark matter (SQM), with comparable amounts of u, d, and s quarks. The possibility of quark matter with only u and d quarks (udQM) is usually dismissed because of the observed stability of ordinary nuclei. However, we find that udQM generally has lower bulk energy per baryon than normal nuclei and SQM. This emerges in a phenomenological model that describes the spectra of the lightest pseudoscalar and scalar meson nonets. Taking into account the finite size effects, udQM can be the ground state of baryonic matter only for baryon number A>A_{min} with A_{min}≳300. This ensures the stability of ordinary nuclei and points to a new form of stable matter just beyond the periodic table.
More sum rules for quark and lepton masses
International Nuclear Information System (INIS)
Terazawa, Hidezumi.
1990-04-01
Sum rules for quark and lepton masses are derived from the Ward identity of Chanowitz and Ellis for the vertex function of the trace of the energy-momentum tensor and the two axial-vector currents and the partially conserved axial-vector current hypothesis. They indicate, among other things, that the constituent quark masses of u and d and those of the techniquarks, if any, are about 300 MeV and 300 GeV, respectively. (author)
Determination of quark-antiquark potentials and meson spectra
International Nuclear Information System (INIS)
Semay, C.; Silvestre-Brac, B.
1999-01-01
We determine two different sets of quark-antiquark potential to be used in a Schroedinger or a Salpeter type of equation. The central part contains QCD inspired components: the Coulomb like interaction, the confinement potential and an instanton interaction. It is supplemented with phenomenological relativistic corrections. The constituent quarks are characterized by a colour charge density. The parameters are determined by a minimization procedure on representative samples of mesons and the full spectra are calculated. Refs. 6, tabs. 2 (author)
Heavy quark symmetry at large recoil: The case of baryons
International Nuclear Information System (INIS)
Koerner, J.G.; Kroll, P.
1992-02-01
We analyze the large recoil behaviour of heavy baryon transition form factors in semi-leptonic decays. We use a generalized Brodsky-Lepage hard scattering formalism where diquarks are considered as quasi-elementary constituents of baryons. In the limit of infinitely heavy quark masses the large recoil form factors exhibit a new model-independent heavy quark symmetry which is reminiscent but not identical to the Isgur-Wise symmetry at low recoil. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Hinzmann, Andreas Dominik
2011-10-07
The Large Hadron Collider (LHC) at the Conseil Europeen pour la Recherche Nucleaire (CERN) allows to study the interactions of quarks and gluons in a yet unexplored energy regime. In 2010, the LHC delivered an integrated luminosity of more than 36 pb{sup -1} of proton-proton collisions at a center-of-mass energy of {radical}(s)=7 TeV. In these proton-proton collisions, the interactions of the constituent quarks and gluons produced a considerable amount of jets of particles with transverse momenta above 1 TeV. Well suited for the study of these jet processes is the Compact Muon Solenoid (CMS) experiment situated at the LHC point 5 as it can measure jets with the necessary energy and angular resolutions over a large range of transverse momentum ({proportional_to}30 GeV
quarks (quark compositeness). Models describing quarks as bound states of constituent particles may be able to explain the number of quark generations, quark masses and charges. A common signature of these models are additional contact interactions between quarks in high-momentum-transfer interactions, observable in the cross section of jet processes. Inspired by the Rutherford experiment, the scattering angle of two-jet processes (dijets) is measured to study the point-like quark and gluon scattering processes predicted by QCD. The dijet scattering angle is expressed in terms of {chi}{sub dijet} = e {sup vertical} {sup stroke} {sup y{sub 1}-y
Energy Technology Data Exchange (ETDEWEB)
Hinzmann, Andreas Dominik
2011-10-07
The Large Hadron Collider (LHC) at the Conseil Europeen pour la Recherche Nucleaire (CERN) allows to study the interactions of quarks and gluons in a yet unexplored energy regime. In 2010, the LHC delivered an integrated luminosity of more than 36 pb{sup -1} of proton-proton collisions at a center-of-mass energy of {radical}(s)=7 TeV. In these proton-proton collisions, the interactions of the constituent quarks and gluons produced a considerable amount of jets of particles with transverse momenta above 1 TeV. Well suited for the study of these jet processes is the Compact Muon Solenoid (CMS) experiment situated at the LHC point 5 as it can measure jets with the necessary energy and angular resolutions over a large range of transverse momentum ({proportional_to}30 GeV
quarks (quark compositeness). Models describing quarks as bound states of constituent particles may be able to explain the number of quark generations, quark masses and charges. A common signature of these models are additional contact interactions between quarks in high-momentum-transfer interactions, observable in the cross section of jet processes. Inspired by the Rutherford experiment, the scattering angle of two-jet processes (dijets) is measured to study the point-like quark and gluon scattering processes predicted by QCD. The dijet scattering angle is expressed in terms of {chi}{sub dijet} = e {sup vertical} {sup stroke} {sup y{sub 1}-y
Quark interchange model of baryon interactions
Energy Technology Data Exchange (ETDEWEB)
Maslow, J.N.
1983-01-01
The strong interactions at low energy are traditionally described by meson field theories treating hadrons as point-like particles. Here a mesonic quark interchange model (QIM) is presented which takes into account the finite size of the baryons and the internal quark structure of hadrons. The model incorporates the basic quark-gluon coupling of quantum chromodynamics (QCD) and the MIT bag model for color confinement. Because the quark-gluon coupling constant is large and it is assumed that confinement excludes overlap of hadronic quark bags except at high momenta, a non-perturbative method of nuclear interactions is presented. The QIM allows for exchange of quark quantum numbers at the bag boundary between colliding hadrons mediated at short distances by a gluon exchange between two quarks within the hadronic interior. This generates, via a Fierz transformation, an effective space-like t channel exchange of color singlet (q anti-q) states that can be identified with the low lying meson multiplets. Thus, a one boson exchange (OBE) model is obtained that allows for comparison with traditional phenomenological models of nuclear scattering. Inclusion of strange quarks enables calculation of YN scattering. The NN and YN coupling constants and the nucleon form factors show good agreement with experimental values as do the deuteron low energy data and the NN low energy phase shifts. Thus, the QIM provides a simple model of strong interactions that is chirally invariant, includes confinement and allows for an OBE form of hadronic interaction at low energies and momentum transfers.
Quark interchange model of baryon interactions
International Nuclear Information System (INIS)
Maslow, J.N.
1983-01-01
The strong interactions at low energy are traditionally described by meson field theories treating hadrons as point-like particles. Here a mesonic quark interchange model (QIM) is presented which takes into account the finite size of the baryons and the internal quark structure of hadrons. The model incorporates the basic quark-gluon coupling of quantum chromodynamics (QCD) and the MIT bag model for color confinement. Because the quark-gluon coupling constant is large and it is assumed that confinement excludes overlap of hadronic quark bags except at high momenta, a non-perturbative method of nuclear interactions is presented. The QIM allows for exchange of quark quantum numbers at the bag boundary between colliding hadrons mediated at short distances by a gluon exchange between two quarks within the hadronic interior. This generates, via a Fierz transformation, an effective space-like t channel exchange of color singlet (q anti-q) states that can be identified with the low lying meson multiplets. Thus, a one boson exchange (OBE) model is obtained that allows for comparison with traditional phenomenological models of nuclear scattering. Inclusion of strange quarks enables calculation of YN scattering. The NN and YN coupling constants and the nucleon form factors show good agreement with experimental values as do the deuteron low energy data and the NN low energy phase shifts. Thus, the QIM provides a simple model of strong interactions that is chirally invariant, includes confinement and allows for an OBE form of hadronic interaction at low energies and momentum transfers
Making quark matter at brook haven's new collider
International Nuclear Information System (INIS)
Jones, P.
2002-01-01
Quarks are believed to come in 6 flavours, only the lightest of which, the up and down quarks, are found in protons and neutrons. Isolated quarks have never been observed. As quarks are brought closer together, the force between them decreases dramatically, vanishing as the separation becomes very small. This suggests that quarks may become unbound if the density of quarks could be increased by squeezing a nucleus. The nucleus would have melted their constituent quarks, now free to roam the extended volume of the compressed nucleus. This situation would make a significant change in the structure of matter corresponding to a change of phase, rather like the transition from solid to liquid, but in this case from quark confined matter, to a quark gluon plasma (QGP). This new state of matter is thought to have been the natural phase of matter until 10 micro-seconds after the big-bang, and also to exist today in the core of neutron stars. Calculations show that the energy density needed to observe the phase transition is around 1 GeV/fm 3 , approximately 8 times that of normal nuclear matter. Attempts to recreate QGP have been underway at the relativistic heavy ion collider (RHIC) and at the CERN by colliding heavy-ion beams at the maximal energy possible. Between 4000 and 5000 charged particles are produced in the most violent events. The experimental challenge is to establish the existence of QGP from all this wealth of data. (A.C.)
Searches for baryons with multiple heavy quarks at LHCb
CERN. Geneva
2017-01-01
Hadrons are systems bound by the strong interaction, which is described at the fundamental level by quantum chromodynamics (QCD). While QCD is well understood at high energy in the perturbative regime, low-energy phenomena, such as the binding of quarks and gluons within hadrons, are more difficult to predict. High precision measurements are then of paramount importance to test the reliability of several models and computational techniques, such as constituent-quark models or lattice-QCD calculations, in predicting the mass spectrum and the properties of hadrons. Owing to its excellent capabilities with particle identification, tracking and vertex reconstruction, LHCb is in a unique position to make significant contributions to the sector of particle spectroscopy. For example, five narrow structures have been recently observed in the $\\Xi_c^+K^-$ mass spectrum, consistent with excited $\\Omega_c^{0}$ states, composed of a charm quark and two strange quarks. Despite the fact that the quark model predicts the ex...
Space-Time Geometry of Quark and Strange Quark Matter
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
We study quark and strange quark matter in the context of general relativity. For this purpose, we solve Einstein's field equations for quark and strange quark matter in spherical symmetric space-times. We analyze strange quark matter for the different equations of state (EOS) in the spherical symmetric space-times, thus we are able to obtain the space-time geometries of quark and strange quark matter. Also, we discuss die features of the obtained solutions. The obtained solutions are consistent with the results of Brookhaven Laboratory, i.e. the quark-gluon plasma has a vanishing shear (i.e. quark-gluon plasma is perfect).
Big Bang to Little Bang ---- Study of Quark-Gluon Plasma
Indian Academy of Sciences (India)
Tapan K. Nayak
2013-07-05
Jul 5, 2013 ... ... compressed into a space billions of times smaller than a proton. ... Quarks in neutron/proton. • Range 10. -13 cm ... Structure of an atom… …separate constituents nucleus electron .... HIGHEST MAN-MADE TEMPERATURE.
Jan-e~Alam; Subhasis~Chattopadhyay; Tapan~Nayak
2008-10-01
Quark Matter 2008—the 20th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions was held in Jaipur, the Pink City of India, from 4-10 February, 2008. Organizing Quark Matter 2008 in India itself indicates the international recognition of the Indian contribution to the field of heavy-ion physics, which was initiated and nurtured by Bikash Sinha, Chair of the conference. The conference was inaugurated by the Honourable Chief Minister of Rajasthan, Smt. Vasundhara Raje followed by the key note address by Professor Carlo Rubbia. The scientific programme started with the theoretical overview, `SPS to RHIC and onwards to LHC' by Larry McLerran followed by several theoretical and experimental overview talks on the ongoing experiments at SPS and RHIC. The future experiments at the LHC, FAIR and J-PARC, along with the theoretical predictions, were discussed in great depth. Lattice QCD predictions on the nature of the phase transition and critical point were vigorously debated during several plenary and parallel session presentations. The conference was enriched by the presence of an unprecedented number of participants; about 600 participants representing 31 countries across the globe. This issue contains papers based on plenary talks and oral presentations presented at the conference. Besides invited and contributed talks, there were also a large number of poster presentations. Members of the International Advisory Committee played a pivotal role in the selection of speakers, both for plenary and parallel session talks. The contributions of the Organizing Committee in all aspects, from helping to prepare the academic programme down to arranging local hospitality, were much appreciated. We thank the members of both the committees for making Quark Matter 2008 a very effective and interesting platform for scientific deliberations. Quark Matter 2008 was financially supported by: Air Liquide (New Delhi) Board of Research Nuclear Sciences (Mumbai) Bose
Electromagnetic properties of light and heavy baryons in the relativistic quark model
International Nuclear Information System (INIS)
Nicmorus Marinescu, Diana
2007-01-01
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
Electromagnetic properties of light and heavy baryons in the relativistic quark model
Energy Technology Data Exchange (ETDEWEB)
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
International Nuclear Information System (INIS)
Zhenping Li; Close, F.E.
1990-03-01
The photo and electroproduction of baryon resonances has been calculated using the Constituent Quark Model with chromodynamics consistent with O(υ 2 /c 2 ) for the quarks. We find that the successes of the nonrelativistic quark model are preserved, some problems are removed and that QCD mixing effects may become important with increasing q 2 in electroproduction. For the first time both spectroscopy and transitions receive a unified treatment with a single set of parameters. (author)
Roles of quarks and gluons in the spin structure of nucleons
International Nuclear Information System (INIS)
Modarres, M.; Amir-Kabir Univ., Teheran; Ghafoori-Tabrizi, K.; Shahid-Beheshti Univ., Teheran
1992-01-01
The spin structure of protons will be discussed by using MIT-bag model and considering constituent quarks to be combined from current quarks and gluons. It will be shown that the gluonic degrees of freedom play an important role in prediction of the recent EMC results. (orig.)
Charge radii of octet and decuplet baryons in chiral constituent ...
Indian Academy of Sciences (India)
in electron–baryon scattering experiments [4,5] giving rp = 0.877 ± 0.007 fm ... breaking of the SU(3) symmetry and a non-vanishing neutron charge mean square radius ... QCD Lagrangian is not invariant under the chiral transformation. ... of a constituent quark GBs [34–37], successfully explains the 'proton spin problem'.
Heavy-quark physics in quantum chromodynamics
International Nuclear Information System (INIS)
Brodsky, S.J.
1991-04-01
Heavy quarks can expose new symmetries and novel phenomena in QCD not apparent in ordinary hadronic systems. In these lectures I discuss the use of effective-Lagrangian and light-cone Fock methods to analyze exclusive heavy hadron decays such as Υ → p bar p and B → ππ, and also to derive effective Schroedinger and Dirac equations for heavy quark systems. Two contributions to the heavy quark structure functions of the proton and other light hadrons are identified: an ''extrinsic'' contribution associated with leading twist QCD evolution of the gluon distribution, and a higher twist ''intrinsic'' contribution due to the hardness of high-mass fluctuations of multi-gluon correlations in hadronic wavefunctions. A non-perturbative calculation of the heavy quark distribution of a meson in QCD in one space and one time is presented. The intrinsic higher twist contributions to the pion and proton structure functions can dominate the hadronic production of heavy quark systems at large longitudinal momentum fraction x F and give anomalous contributions to the quark structure functions of ordinary hadrons at large x bj . I also discuss a number of ways in which heavy quark production in nuclear targets can test fundamental QCD phenomena and provide constraints on hadronic wavefunctions. The topics include color transparency, finite formation time, and predictions for charm production at threshold, including nuclear-bound quarkonium. I also discuss a number of QCD mechanisms for the suppression of J/ψ and Υ production in nuclear collisions, including gluon shadowing, the peripheral excitation of intrinsic heavy quark components at large x F , and the coalescence of heavy quarks with co-moving spectators at low x F
Testa, Massimo
1990-01-01
In the large quark mass limit, an argument which identifies the mass of the heavy-light pseudoscalar or scalar bound state with the renormalized mass of the heavy quark is given. The following equation is discussed: m(sub Q) = m(sub B), where m(sub Q) and m(sub B) are respectively the mass of the heavy quark and the mass of the pseudoscalar bound state.
Bulk viscosity in 2SC quark matter
International Nuclear Information System (INIS)
Alford, Mark G; Schmitt, Andreas
2007-01-01
The bulk viscosity of three-flavour colour-superconducting quark matter originating from the nonleptonic process u + s ↔ u + d is computed. It is assumed that up and down quarks form Cooper pairs while the strange quark remains unpaired (2SC phase). A general derivation of the rate of strangeness production is presented, involving contributions from a multitude of different subprocesses, including subprocesses that involve different numbers of gapped quarks as well as creation and annihilation of particles in the condensate. The rate is then used to compute the bulk viscosity as a function of the temperature, for an external oscillation frequency typical of a compact star r-mode. We find that, for temperatures far below the critical temperature T c for 2SC pairing, the bulk viscosity of colour-superconducting quark matter is suppressed relative to that of unpaired quark matter, but for T ∼> T c /30 the colour-superconducting quark matter has a higher bulk viscosity. This is potentially relevant for the suppression of r-mode instabilities early in the life of a compact star
Quark diquark symmetry breaking
International Nuclear Information System (INIS)
Souza, M.M. de
1980-01-01
Assuming the baryons are made of quark-diquark pairs, the wave functions for the 126 allowed ground states are written. The quark creation and annihilations operators are generalized to describe the quark-diquark structure in terms of a parameter σ. Assuming that all quark-quark interactions are mediated by gluons transforming like an octet of vector mesons, the effective Hamiltonian and the baryon masses as constraint equations for the elements of the mass matrix is written. The symmetry is the SU(6) sub(quark)x SU(21) sub(diquark) broken by quark-quark interactions respectively invariant under U(6), U(2) sub(spin), U(3) and also interactions transforming like the eighth and the third components of SU(3). In the limit of no quark-diquark structure (σ = 0), the ground state masses is titted to within 1% of the experimental data, except for the Δ(1232), where the error is almost 2%. Expanding the decuplet mass equations in terms of σ and keeping terms only up to the second order, this error is reduced to 67%. (Author) [pt
Quarks in hadrons and nuclei and electromagnetic probes
International Nuclear Information System (INIS)
Faessler, Amand
1995-01-01
Deuteron properties and nuclear magnetic moments are studied in the non-relativistic quark cluster model. The quark cluster model is modified to include chiral symmetry. This reduces the number of parameters. The σ meson is exchanged between quarks and not as in earlier versions between nucleons. The charge monopole, quadrupole and magnetic-dipole form factors and the tensor polarization of the deuteron in this microscopic meson-quark cluster model are calculated. The deuteron wave function is derived from a microscopic 6-quark Hamiltonian which, in addition to a quadratic confinement potential, includes the one-pion and the one-gluon exchange potentials between quarks. The electromagnetic current operators are constructed on the quark level, i.e., the photon is coupled directly to the quarks. Aside from the one-body impulse current, pionic and gluonic exchange current corrections are included. Due to the Pauli principle on the quark level, new quark interchange terms arise in the one-body and two-body current matrix elements, that are not present on the nucleon level. While these additional quark exchange currents are small for low momentum transfers, we find that they appreciably influence the electromagnetic structure of the deuteron beyond a momentum transfer of q = 5fm -1 . (author)
Dakin, James T.
1974-01-01
Reviews theoretical principles underlying the quark model. Indicates that the agreement with experimental results and the understanding of the quark-quark force are two hurdles for the model to survive in the future. (CC)
The catamorphy of quark-lepton families
International Nuclear Information System (INIS)
Wilkinson, D.H.
1988-11-01
Quark-lepton families appear to be limited in number. This can be understood if they are catamorphically related. This is illustrated by a simple geometrical Ansatz that gives the correct number of fermion fields per family and limits the number of families to three
The quark propagator in a covariant gauge
International Nuclear Information System (INIS)
Bonnet, F.D.R.; Leinweber, D.B.; Williams, A.G.; Zanotti, J.M.
2000-01-01
Full text: The quark propagator is one of the fundamental building blocks of QCD. Results strongly depend on the ansatz for the propagator. Direct simulations of QCD on a space time lattice can provide guidance and constraints on the analytic structure of the quark propagator. On the lattice the infrared and asymptotic behaviour of the quark propagator is of particular interest since it is a reflection of the accuracy of the discretised quark action. In the deep infrared region, artefacts associated with the finite size of the lattice spacing become small. This is the most interesting region as nonperturbative physics lies here. However, the ultraviolet behaviour at large momentum of the propagator will in general strongly deviate from the correct continuum behaviour. This behaviour will be action dependent. Some interesting progress has been made in improving the ultraviolet behaviour of the propagator. A method, recently developed and referred to as tree-level correction, consists of using the knowledge of the tree-level behaviour to eliminate the obvious lattice artefacts. Tree-level correction represents a crucial step in extracting meaningful results for the mass function and the renormalisation function outside of the deep infrared region. The mass function is particularly interesting as it provides insights into the constituent quark mass as a measure of the nonperturbative physics. In this poster I will present results from the analytic structure of the propagator in recent lattice studies for a variety of fermion actions in lattice QCD. I will also present the new ratio method used to tree-level correct these quark propagators
Quark ensembles with the infinite correlation length
Zinov'ev, G. M.; Molodtsov, S. V.
2015-01-01
A number of exactly integrable (quark) models of quantum field theory with the infinite correlation length have been considered. It has been shown that the standard vacuum quark ensemble—Dirac sea (in the case of the space-time dimension higher than three)—is unstable because of the strong degeneracy of a state, which is due to the character of the energy distribution. When the momentum cutoff parameter tends to infinity, the distribution becomes infinitely narrow, leading to large (unlimited) fluctuations. Various vacuum ensembles—Dirac sea, neutral ensemble, color superconductor, and BCS state—have been compared. In the case of the color interaction between quarks, the BCS state has been certainly chosen as the ground state of the quark ensemble.
Quark ensembles with the infinite correlation length
International Nuclear Information System (INIS)
Zinov’ev, G. M.; Molodtsov, S. V.
2015-01-01
A number of exactly integrable (quark) models of quantum field theory with the infinite correlation length have been considered. It has been shown that the standard vacuum quark ensemble—Dirac sea (in the case of the space-time dimension higher than three)—is unstable because of the strong degeneracy of a state, which is due to the character of the energy distribution. When the momentum cutoff parameter tends to infinity, the distribution becomes infinitely narrow, leading to large (unlimited) fluctuations. Various vacuum ensembles—Dirac sea, neutral ensemble, color superconductor, and BCS state—have been compared. In the case of the color interaction between quarks, the BCS state has been certainly chosen as the ground state of the quark ensemble
Quark ensembles with the infinite correlation length
Energy Technology Data Exchange (ETDEWEB)
Zinov’ev, G. M. [National Academy of Sciences of Ukraine, Bogoliubov Institute for Theoretical Physics (Ukraine); Molodtsov, S. V., E-mail: molodtsov@itep.ru [Joint Institute for Nuclear Research (Russian Federation)
2015-01-15
A number of exactly integrable (quark) models of quantum field theory with the infinite correlation length have been considered. It has been shown that the standard vacuum quark ensemble—Dirac sea (in the case of the space-time dimension higher than three)—is unstable because of the strong degeneracy of a state, which is due to the character of the energy distribution. When the momentum cutoff parameter tends to infinity, the distribution becomes infinitely narrow, leading to large (unlimited) fluctuations. Various vacuum ensembles—Dirac sea, neutral ensemble, color superconductor, and BCS state—have been compared. In the case of the color interaction between quarks, the BCS state has been certainly chosen as the ground state of the quark ensemble.
Frixione, Stefano; Nason, Paolo; Ridolfi, Giovanni
1997-01-01
We review the present theoretical and experimental status of heavy quark production in high-energy collisions. In particular, we cover hadro- and photoproduction at fixed target experiments, at HERA and at the hadron colliders, as well as aspects of heavy quark production in e+e- collisions at the Z0 peak.
International Nuclear Information System (INIS)
Frampton, P.H.; Jarlskog, C.
1985-01-01
It is shown that the quark mass matrices in the Standard Electroweak Model satisfy the empirical relation M = M 1 + Ψ(Λ 2 ), where M(M sp (')) refers to the mass matrix of the charge 2/3(-1/3) quarks normalized to the largest eigenvalue, m sub (t)(m sub (b)), and Λ = V sub (us) = 0.22
Colourless confinement for quarks
International Nuclear Information System (INIS)
Anon.
1994-01-01
The enigma of quarks is that they are there, hidden deep inside nucleons and other strongly interacting particles, but refuse to come out. The tighter the quark bonds are stretched, the more difficult they are to break. This dogma has been accepted for some thirty years but has never been mathematically proved
International Nuclear Information System (INIS)
Cartwright, Susan
1992-01-01
Like any other electrically charged particles, quarks should give out electromagnetic radiation (photons) when they vibrate. One of the physics results from CERN's LEP collider is the first clear observation of this quark radiation from electron-positron collisions. At lower energies this radiation could only be inferred
Energy Technology Data Exchange (ETDEWEB)
Cartwright, Susan
1992-04-15
Like any other electrically charged particles, quarks should give out electromagnetic radiation (photons) when they vibrate. One of the physics results from CERN's LEP collider is the first clear observation of this quark radiation from electron-positron collisions. At lower energies this radiation could only be inferred.
International Nuclear Information System (INIS)
Larios, F.
2006-01-01
We give an overview of the physics of the Top quark, from the experimental discovery to the studies of its properties. We review some of the work done on the Electroweak and Flavor Changing couplings associated with the Top quark in the Standard Model and beyond. We will focus on the specific contribution of phycisits working in Mexico and Mexican physicists working abroad
International Nuclear Information System (INIS)
Azimov, Ya.I.; Khoze, V.A.
1979-01-01
Experimental results which proved the reality of quarks are reviewed along with further experiments broadening the representation of quarks and leptons and providing the basis to develop the theory of elementary particles. The discovery of the J/psi particle is noted to give rise to the discovery of c-quark, the existance of which is confirmed by the discovery of charmed hadrons. The main aspects of quantum chromodynamics explaining the mechanism of strong interaction of quarks are considered along with those of the Weinberg-Salam theory proposed to describe weak and electromagnetic interactions of quarks and leptons. Experimental data testifying to the existance of heavy tausup(+-) leptons are presented. The history of discovery of γ mesons and of a new heavier b-quark is described. Perspectives for studying elementary particles are discussed. Further studies of γ mesons, discovery and investigation of charmed particles are noted to be immediate tasks along with the search for manifestation of t-quark considered to be a partner of b-quark from the viewpoint of the Weinberg-Salam model
Critical parameters of Quark-Hadron phase transition with interacting and massive quarks
International Nuclear Information System (INIS)
Singh, C.P.; Patra, B.K.
1994-06-01
Current techniques to simulate the dynamical behaviour of Quark-Gluon Plasma (QGP) reveal that the order of the phase transition as well as the values of the critical parameters depend on the number of quark flavours as well as on the quark-masses included in the simulation. We attempt to show here the effects of the number of quark flavours and quark-masses on critical parameters by using the perturbative, finite temperature field theory to g 3 s order in the strong coupling g s . We treat the hadrons as particles with finite size and its implications on the equation of state for hadron gas are studied. We find that the critical temperature T c is lowered by 9 MeV as we move from two to three quark flavours. The nature of the phase transition always remains as first order. However, the inclusion of quark-masses in our calculation does not affect the result much. (author). 14 refs, 3 figs
A relativized quark model for radiative baryon transitions
International Nuclear Information System (INIS)
Warns, M.; Schroeder, H.; Pfeil, W.; Rollnik, H.
1989-03-01
In this paper we investigate the electromagnetic form factors of baryons and their resonances using the framework of a relativized constituent quark model. Beyond the usual single-quark transition ansatz, we incorporate relativistic corrections which are well-determined by the intrinsic strong interaction and confinement forces between the quarks. Furthermore we separate off for the compound three-quark system the relativistic center-of-mass motion by an approximately Lorentz-invariant approach. In this way for the first time recoil effects could be explicitly studied. Using the harmonic oscillator wavefunctions with the configuration mixing as derived in the Isgur-Karl model, after restoring gauge invariance our relativized interaction hamiltonian can be used to calculate the transversely and longitudinally polarized photon transition form factors of the baryons. (orig.)
Quark self-energy beyond the mean field at finite temperature
International Nuclear Information System (INIS)
Zhuang, P.
1995-01-01
The Nambu--Jona-Lasinio model, an effective low-energy model of QCD, is extended to the next to the leading order in the 1/N c expansion at finite temperature and density. The contributions to the quark self-energy and the constituent quark mass from the meson dressing are considered in a perturbative approach about the mean field. In particular, the temperature dependence of the quark mass is shown numerically at zero chemical potential. The correction to the quark mass from the meson dressing amounts to 20% compared to the result of the leading order at low temperature, and rapidly approaches zero at high temperature
A nucleon description based on confinement and a dynamic generation of the quark masses
International Nuclear Information System (INIS)
Caillon, J.C.
2010-01-01
We have considered the nucleon as an MIT bag, but instead of a perturbative vacuum, we use a QCD vacuum modified as compared to the outside space and hence a modified quark-condensate. Quarks acquire their constituent-masses through their interactions with this modified QCD vacuum in a framework of an NJL model. The value of the quark condensate modified in the nucleon is then determined self-consistently by the equilibrium condition for the bag: the outward pressure due to both the motion of three quarks and the modified vacuum in the nucleon must be counterbalanced by the inward pressure of the vacuum outside the bag. We are able to pass continuously from a nucleon description in a pure MIT bag model to a description using constituent quark masses determined in an NJL model.
A scalar-vector model of quark-antiquark interaction under linear confinement
International Nuclear Information System (INIS)
Chakrabarty, S.
1992-08-01
Considering the idea that the constituent quark mass is the dressed sum of current quark mass and dynamical quark mass, and using the standard values of current quark masses we obtain approximate values of constituent quark masses, which are then used in our extensively studied Bethe-Salpeter-reduced potential model. We find that the mass formulas become much simpler for linear potential ar with zero anomalous magnetic moment (λ), the values of scalar-vector fraction (η) and 'a' in the linear potential being (1/4) and (1/5) respectively. Also, some of the quantities can be related to each other and the match with experimental data is good. (author). 18 refs, 3 tabs
Quark confinement and the quark model
International Nuclear Information System (INIS)
Kuti, J.
1977-01-01
The CERN-JINR School of Physics is meant to give young experimental physicists and introduction to the theoretical aspects of recent advances in elementary particle physics. The purpose of the lectures contained in this paper is to discuss recent work on the quark model and its applications to hadron spectroscopy and some high-energy phenomena. (Auth.)
Fritzsch, Harald
1983-01-01
Quark rossi, verdi e blu ; quark dotati di stranezza e di incanto ; quark 'su' e 'giù' : sembra che i fisici delle particelle giochino a confondere la curiosità del profano, con queste denominazioni fantasiose. Che cosa significano ? e, soprattutto, i quark sono i costituenti davvero elementari della materia ?
Top Quark Properties at Tevatron
Energy Technology Data Exchange (ETDEWEB)
Lysák, Roman [Prague, Inst. Phys.
2017-11-27
The latest CDF and D0 experiment measurements of the top quark properties except the top quark mass are presented. The final combination of the CDF and D0 forward-backward asymmetry measurements is shown together with the D0 measurements of the inclusive top quark pair cross-section as well as the top quark polarization.
Relativistic form factors for hadrons with quark-model wave functions
International Nuclear Information System (INIS)
Stanley, D.P.; Robson, D.
1982-01-01
The relationship between relativistic form factors and quark-potential-model wave functions is examined using an improved version of an approach by Licht and Pagnamenta. Lorentz-contraction effects are expressed in terms of an effective hadron mass which varies as the square root of the number of quark constituents. The effective mass is calculated using the rest-frame wave functions from the mean-square momentum along the direction of the momentum transfer. Applications with the parameter-free approach are made to the elastic form factors of the pion, proton, and neutron using a Hamiltonian which simultaneously describes mesons and baryons. A comparison of the calculated radii for pions and kaons suggests that the measured kaon radius should be slightly smaller than the corresponding pion radius. The large negative squared charge radius for the neutron is partially explained via the quark model but a full description requires the inclusion of a small component of a pion ''cloud'' configuration. The problematic connection between the sizes of hadrons deduced from form factors and the ''measured'' values of average transverse momenta is reconciled in the present model
A chiral quark model of the nucleon
International Nuclear Information System (INIS)
Wakamatsu, M.; Yoshiki, H.
1991-01-01
The baryon-number-one extended solution of a chiral quark lagrangian is obtained in the stationary-phase approximation with full inclusion of the sea-quark degrees of freedom. The collective quantization method is then applied to this static solution to obtain the nucleon (and Δ) state with the definite spin and isospin. A fundamental quantity appearing in this quantization procedure is the moment of inertia of the soliton system. We evaluate this quantity without recourse to the derivative expansion, by performing the necessary double sum over all the positive- and negative-energy quark orbitals in the mean field potential. Closed formulas are-derived for the nucleon (and Δ) matrix elements of arbitrary quark bilinear operators. These formulas are then used for calculating various nucleon observables in a nonperturbative manner with inclusion of the sea-quark effects. An especially interesting observable is the spin expectation value of the proton related to the recent EMC experiment. We derive the proton spin sum rule, and then explicitly evaluate the detailed contents of this sum rule. The proton spin analysis is shown to be particularly useful for clarifying the underlying dynamical content of the Skyrme model at quark level, thereby providing us with valuable information about its utility and limitation. (orig.)
Experimental constraint on quark electric dipole moments
Liu, Tianbo; Zhao, Zhiwen; Gao, Haiyan
2018-04-01
The electric dipole moments (EDMs) of nucleons are sensitive probes of additional C P violation sources beyond the standard model to account for the baryon number asymmetry of the universe. As a fundamental quantity of the nucleon structure, tensor charge is also a bridge that relates nucleon EDMs to quark EDMs. With a combination of nucleon EDM measurements and tensor charge extractions, we investigate the experimental constraint on quark EDMs, and its sensitivity to C P violation sources from new physics beyond the electroweak scale. We obtain the current limits on quark EDMs as 1.27 ×10-24 e .cm for the up quark and 1.17 ×10-24 e .cm for the down quark at the scale of 4 GeV2 . We also study the impact of future nucleon EDM and tensor charge measurements, and show that upcoming new experiments will improve the constraint on quark EDMs by about 3 orders of magnitude leading to a much more sensitive probe of new physics models.
International Nuclear Information System (INIS)
Anisovich, V.V.
1989-06-01
Using the language of the quarks and gluons for description of the soft hadron physics it is necessary to take into account two characteristic phenomena which prevent one from usage of QCD Lagrangian in the straightforward way, chiral symmetry breaking, and confinement of colour particles. The topics discussed in this context are: QCD in the domain of soft processes, phenomenological Lagrangian for soft processes and exotic mesons, spectroscopy of low-lying hadrons (mesons, baryons and mesons with heavy quarks - c,b -), confinement forces, spectral integration over quark masses. (author) 3 refs.; 19 figs.; 3 tabs
Energy Technology Data Exchange (ETDEWEB)
Goldhaber, J.
1986-11-13
The paper concerns the experimental search for quark-gluon plasma. The theory of a quark-gluon plasma is first given. Then the method which researchers hope will create the quark-gluon plasma is described; the idea is to use heavy ion beams in, the CERN SPS. The CERN 'heavy-ion programme' involves research groups mainly from CERN, Lawrence Berkeley Laboratory and Gellsellschaft fuer Schwerionenforschung. The experiments in the research programme are outlined, together with the detector equipment employed in the experiments.
Quark mass correction to chiral separation effect and pseudoscalar condensate
Energy Technology Data Exchange (ETDEWEB)
Guo, Er-dong [State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics,Chinese Academy of Sciences,Beijing 100190 (China); Kavli Institute of Theoretical Physics China, Chinese Academy of Sciences,Beijing 100190 (China); Lin, Shu [School of Physics and Astronomy, Sun Yat-Sen University,No 2 University Road, Zhuhai 519082 (China)
2017-01-25
We derived an analytic structure of the quark mass correction to chiral separation effect (CSE) in small mass regime. We confirmed this structure by a D3/D7 holographic model study in a finite density, finite magnetic field background. The quark mass correction to CSE can be related to correlators of pseudo-scalar condensate, quark number density and quark condensate in static limit. We found scaling relations of these correlators with spatial momentum in the small momentum regime. They characterize medium responses to electric field, inhomogeneous quark mass and chiral shift. Beyond the small momentum regime, we found existence of normalizable mode, which possibly leads to formation of spiral phase. The normalizable mode exists beyond a critical magnetic field, whose magnitude decreases with quark chemical potential.
Effect of soft mode on shear viscosity of quark matter
International Nuclear Information System (INIS)
Fukutome, Takahiko; Iwasaki, Masaharu
2008-01-01
We calculate the shear viscosity of quark matter at finite temperature and density. If we assume that the quark interacts with the soft mode, which is a collective mode of a quark-antiquark pair, the self-energy of the quark is calculated by quasi-particle random phase approximation. It is shown that its imaginary part is large and its mean free path is short. With the use of the Kubo formula, the shear viscosity of quark matter decreases. The Reynolds number of quark matter is estimated to be about 10. As temperature increases, shear viscosity increases gradually for T>200 MeV. Moreover it is shown that the shear viscosity also increases with the chemical potential for μ>200 MeV. (author)
Top quark measurements at ATLAS
Grancagnolo, Sergio; The ATLAS collaboration
2017-01-01
The top quark is the heaviest known fundamental particle. As it is the only quark that decays before it hadronizes, this gives us the unique opportunity to probe the properties of bare quarks at the Large Hadron Collider. This talk will present highlights of a few recent precision measurements by the ATLAS Collaboration of the top quark using 13 TeV and 8 TeV collision data: top-quark pair and single top production cross sections including differential distributions will be presented alongside top quark properties measurements. These measurements, including results using boosted top quarks, probe our understanding of top quark production in the TeV regime. Measurements of the top quark mass and searches for rare top quark decays are also presented.
Top quark measurements at ATLAS
AUTHOR|(INSPIRE)INSPIRE-00041686; The ATLAS collaboration
2017-01-01
The top quark is the heaviest known fundamental particle. As it is the only quark that decays before it hadronizes, it allows us to probe the properties of bare quarks at the Large Hadron Collider. Highlights of a few recent precision measurements by the ATLAS Collaboration of the top quark using 13 TeV and 8 TeV collision data will be presented: top-quark pair and single top production cross sections including differential distributions will be presented alongside measurements of top-quark properties, including results using boosted top quarks, probe our understanding of top-quark production in the TeV regime. Measurements of the top-quark mass and searches for rare top quark decays are also presented.
Spinodal instability of baryon-rich quark matter
International Nuclear Information System (INIS)
Li, Feng; Ko, Che Ming
2017-01-01
The spinodal instabilities of both confined and expanding baryon-rich quark matters are studied in a transport model derived from the Nambu-Jona-Lasino model. Appreciable higher-order density moments are seen as a result of the first-order phase transition in both cases. The skewness of the quark number event-by-event distribution in a small subvolume of the system becomes appreciable for the confined quark matter. For the expanding quark matter, the density fluctuations lead to enhanced anisotropic flows and dilepton yield. (paper)
Institute of Scientific and Technical Information of China (English)
ZONG Hong-Shi; PING Jia-Lun; SUN Wei-Min; CHANG Chao-Hsi; WANG Fan
2002-01-01
We exhibit a method for obtaining the low chemical potential dependence of the dressed quark propagatorfrom an effective quark-quark interaction model. Within this approach we explore the chemical potential dependenceof the dressed-quark propagator, which provides a means of determining the behavior of the chiral and deconfinementorder parameters. A comparison with the results of previous researches is given.
International Nuclear Information System (INIS)
Luttrell, S.P.; Wada, S.; Webber, B.R.
1981-01-01
We calculate the leading order Wilson coefficient functions of the four-quark operators in the current product expansion. The process dependence of the contributions of the four-quark operators is given, and it is argued that they are likely to be negative. It is also argued that the spin (n) dependence of the ratio of the four-quark term to the twist-two terms is linear in n (or at most proportional n log n), though the number of independent four-quark operators grows like n 2 . (orig.)
Strong interactions - quark models
International Nuclear Information System (INIS)
Goto, M.; Ferreira, P.L.
1979-01-01
The variational method is used for the PSI and upsilon family spectra reproduction from the quark model, through several phenomenological potentials, viz.: linear, linear plus coulomb term and logarithmic. (L.C.) [pt
Multileptons from heavy quarks
International Nuclear Information System (INIS)
Phillips, R.J.N.
1984-03-01
The paper is concerned with a brief look at the various multilepton signals that are expected at p-barp colliders from the production and cascade decay of top quarks, plus the backgrounds from b and c production. (author)
International Nuclear Information System (INIS)
Roberts, R.G.
1984-11-01
The paper concerns the behaviour of quarks in nuclei. Confinement size changes and dynamical rescaling; A dependence; low-x region; gluons and confinement size; and nucleons in a nucleus; are all discussed. (U.K.)
International Nuclear Information System (INIS)
Guersey, F.
1974-01-01
A mathematical framework based on octonions is developed for the description of the color quark scheme in which quarks are unobservable, the color SU(3) is exact, and only color singlets correspond to observable hadrons. The fictitious Hilbert space in which quarks operate is taken to be a space of vectors with octonion components. This space admits as a gauge group an exact SU(3) identified with the color SU/sub C/(3). Because of the nonassociativity of the underlying algebra, nonsinglet representations of SU/sub C/(3) are unobservable, while the subspace of color singlets satisfies associativity along with conditions for observability. Octonion quark fields satisfy the commutation relations of parafermions of order 3, leading to the correct SU(6) multiplets for hadrons. (U.S.)
International Nuclear Information System (INIS)
Anon.
1995-01-01
Nine months after a careful announcement of tentative evidence for the long-awaited sixth 'top' quark, physicists from the CDF and DO experiments at Fermilab's Tevatron proton-antiproton collider declared on 2 March that they had finally discovered the top quark. Last year (June 1994, page 1), the CDF experiment at the Tevatron reported a dozen candidate top events. These, said CDF, had all the characteristics expected of top, but the difficulties of extracting the tiny signal from a trillion proton-antiproton collisions made them shy of claiming a discovery. For its part, the companion DO Tevatron experiment reported a few similar events but were even more guarded about their interpretation as top quarks. Just after these hesitant announcements, performance at the Tevatron improved dramatically last summer. After the commissioning of a new linear accelerator and a magnet realignment, the machine reached a new world record proton-antiproton collision luminosity of 1.28 x 10 31 per sq cm per s, ten times that originally planned. Data began to pour in at an unprecedented rate and the data sample grew to six trillion collisions. Luminosity has subsequently climbed to 1.7 x 10 31 . The top quark is the final letter in the alphabet of Standard Model particles. According to this picture, all matter is composed of six stronglyinteracting subnuclear particles, the quarks, and six weakly interacting particles, the leptons. Both sextets are neatly arranged as three pairs in order of increasing mass. The fifth quark, the 'beauty' or 'b' quark, was also discovered at Fermilab, back in 1977. Since then physicists have been eagerly waiting for the top to turn up, but have been frustrated by its heaviness - the top is some 40 times the mass of its 'beautiful' partner. Not only is the top quark the heaviest by far, but it is the only quark which has been actively hunted. After the quarry was glimpsed last year, the net has now been
Heavy hadron spectroscopy: A quark model perspective
International Nuclear Information System (INIS)
Vijande, J.; Valcarce, A.; Caramés, T.F.; Garcilazo, H.
2013-01-01
We present recent results of hadron spectroscopy and hadron–hadron interaction from the perspective of constituent quark models. We pay special attention to the role played by higher order Fock space components in the hadron spectra and the connection of this extension with the hadron–hadron interaction. The main goal of our description is to obtain a coherent understanding of the low-energy hadron phenomenology without enforcing any particular model, to constrain its characteristics and learn about low-energy realization of the theory
DEFF Research Database (Denmark)
Sørensen, Paul Haase; Taylor, John C.
1984-01-01
Processes with coloured particles in the initial state are generally infrared divergent. We investigate the effect of this on processes with colourless particles in the initial state, when the amplitude is near an intermediate quark pole. The result is a characteristic logarithmic depedence...... on the 'binding energy'(even though spectator interactions are taken into account), and the result is gauge-invariant. Summed to all orders the logarithms could perhaps suppress the quark pole....
Surface structure of quark stars with magnetic fields
Indian Academy of Sciences (India)
We investigate the impact of magnetic fields on the electron distribution of the electrosphere of quark stars. For moderately strong magnetic fields of ∼ 1013 G, quantization effects are generally weak due to the large number density of electrons at surface, but can nevertheless affect the photon emission properties of quark ...
Twisted mass lattice QCD with non-degenerate quark masses
International Nuclear Information System (INIS)
Muenster, Gernot; Sudmann, Tobias
2006-01-01
Quantum Chromodynamics on a lattice with Wilson fermions and a chirally twisted mass term is considered in the framework of chiral perturbation theory. For two and three numbers of quark flavours, respectively, with non-degenerate quark masses the pseudoscalar meson masses and decay constants are calculated in next-to-leading order including lattice effects quadratic in the lattice spacing a
Prediction of new Quarks, Generations and Quark Masses
Lach, Thedore
2002-04-01
The Standard model currently suggests no relationship between the quark and lepton masses. The CBM (model) of the nucleus has resulted in the prediction of two new quarks, an up quark mass of 237.31 MeV/c2 and a dn quark mass of 42.392 MeV/c2. These two new quarks help explain the numerical relationship between all the quark and lepton masses in a single function. The mass of each SNU-P (quark or lepton) is just the geometric mean of two related SNU-Ps, either in the same generation or in the same family. This numerology predicts the following masses for the electron family: 0.511000 (electron), 7.743828 (predicted), 117.3520, 1778.38, 26950.08 MeV. The resulting slope of these masses when plotted on semi log paper is "e" to 5 significant figures using the currently accepted mass for Tau. This theory suggests that all the "dn like" quarks have a mass of just 10X multiples of 4.24 MeV (the mass of the "d" quark). The first 3 "up like" quark masses are 38, 237 and 1500 MeV. This theory also predicts a new heavy generation with a lepton mass of 27 GeV, a "dn like" quark of 42.4 GeV, and an "up like" quark of 65 GeV. Significant evidence already exists for the existence of these quarks, and lepton.
Diffractive dissociation and new quarks
International Nuclear Information System (INIS)
White, A.R.
1983-04-01
We argue that the chiral limit of QCD can be identified with the strong (diffractive dissociation) coupling limit of reggeon field theory. Critical Pomeron scaling at high energy must then be directly related to an infra-red fixed-point of massless QCD and so requires a large number of flavors. This gives a direct argument that the emergence of diffraction-peak scaling, KNO scaling etc. at anti p-p colliders are evidence of a substantial quark structure still to be discovered
A QCD derivation of the additive quark model from two and three gluon exchanges
International Nuclear Information System (INIS)
Lipkin, H.J.
1982-06-01
The contributions to the Pomeron from two and three gluon exchanges are shown to give the correct combinatorial factors for the additive quark model relation between meson and baryon Pomeron couplings, even though two-quark and three-quark operators are involved. Similar results hold for the contributions to hadron masses from three-gluon vertices as well as one-gluon exchange. The color algebra reduces the multiquark couplings to a linear function of quark number. (author)
Color quarks as a new stage of knowledge of microcosm
International Nuclear Information System (INIS)
Bogolyubov, N.N.
1985-01-01
The theory of color quarks is discussed in a popular form. The idea of color quarks lies in the main principle of modern conceptions of the world of elementary particles and atomic nuclei. In 1965 in the studies of A.N. Tavkhelidze, B.V. Struminsky and N.N. Bogolyubov as well as independently in the studies of M. Khan, E.Nambu and J.Miyamote the hypothesis on the presence of a new quantum number of quarks called subsequently color has been suggested. For each type of quarks with specified values of isotopic spin, electrical charge and strangeness three unitary-equivalent states which differ in the values of the new quantum number - color exist. The hypothesis of color quarks turned out cardinal idea which cleared the way to the solution of fundamental problems of the theory of elementary particles
Heavy quark fragmentation functions in the heavy quark effective theory
International Nuclear Information System (INIS)
Martynenko, A.P.; Saleev, V.A.
1996-01-01
The fragmentation of b-bar-antiquark into polarized B c * -mesons and b-quark into P-wave (c-bar b) states in the Heavy Quark Effective Theory. The heavy quark fragmentation functions in longitudinally and transversely polarized S-wave b-bar c-states and P-wave mesons containing b-, c-quarks also, with the exact account of corrections of first order in 1/m b . 20 refs., 2 figs
A quark structure of hadrons and nuclei
International Nuclear Information System (INIS)
Chakrabarty, S.; Deoghuria, S.
1992-08-01
In this review we look into the recent understanding of mesons, baryons and nuclei as few quark bound states within the framework of quantum chromodynamics (QCD). In particular, we have reviewed our understanding of the nature of confining interaction, the spin - dependence of colour forces and the role of non-perturbative effects in the study of quark forces in the potential model approach. We also give a comparative study of results obtained by several potential models with reference to the experimental data. We find that although the Lorentz nature of confinement and the nature of spin-dependent colour forces have been better understood now, only a partial understanding of these problems are obtained so far. Our study reveals that properties of baryons could be explained by the same potential model which successfully describe the mesons. However, the nuclei require chiral symmetry and non-perturbative methods for their description. We also discuss the relation between constituent, current and dynamical quark masses. We conclude that QCD motivated approaches have shown much success in explaining many results on hadronic and nuclear data. (author). 212 refs, 14 tabs
A quark interpretation of the combinatorial hierarchy
International Nuclear Information System (INIS)
Enqvist, Kari.
1979-01-01
We propose a physical interpretation of the second level of the combinatorial hierarchy in terms of three quarks, three antiquarks and the vacuum. This interpretation allows us to introduce a new quantum number, which measures electromagnetic mass splitting of the quarks. We extend our argument by analogue to baryons, and find some SU(3) and some new mass formulas for baryons. The generalization of our approach to other hierarchy levels is discussed. We present also an empirical mass formula for baryons, which seems to be loosely connected with the combinatorial hierarchy. (author)
Single top quark production at LEP200?
International Nuclear Information System (INIS)
Boos, E.; Ishikawa, T.; Kaneko, T.; Kawabata, S.; Kurihara, Y.; Shimizu, Y.; Tanaka, H.
1994-01-01
A complete tree-level calculation of the reaction e + e - → e + ν e anti tb (e - anti ν e t anti b) in the electroweak standard theory in the LEP200 energy range is presented. For top quark masses in the range 130 to 190 GeV the cross sections are found to be in the order of 10 -5 to 10 -6 pb. Therefore, the number of single top quark events is expected to be negligible even with an integrated luminosity of L = 500 pb -1 . It is further demonstrated that the Weizsaecker-Williams approximation is approaching the accurate cross section calculations resonably well. (orig.)
The fourth family of quarks and leptons
International Nuclear Information System (INIS)
Cline, D.B.; Soni, A.
1987-01-01
This book presents the proceedings of The Fourth Family of Quarks and Leptons. Topics covered include: Missing Transverse Energy Events and a Search for Additional Neutrino Families and a Fourth-Generation Lepton; Cosmological Limit on the Number of Families; and Charmed Baryon Decay
The heavy top quark and supersymmetry
Energy Technology Data Exchange (ETDEWEB)
Hall, L.J. [Lawrence Berkeley Lab., CA (United States)]|[Univ. of California, Berkeley, CA (United States)
1997-01-01
Three aspects of supersymmetric theories are discussed: electroweak symmetry breaking, the issues of flavor, and gauge unification. The heavy top quark plays an important, sometimes dominant, role in each case. Additional symmetries lead to extensions of the Standard Model which can provide an understanding for many of the outstanding problems of particle physics. A broken supersymmetric extension of spacetime allows electroweak symmetry breaking to follow from the dynamics of the heavy top quark; an extension of isospin provides a constrained framework for understanding the pattern of quark and lepton masses; and a grand unified extension of the Standard Model gauge group provides an elegant understanding of the gauge quantum numbers of the components of a generation. Experimental signatures for each of these additional symmetries are discussed.
Quark vs Gluon Jet Tagging at ATLAS
Rubbo, Francesco; The ATLAS collaboration
2017-01-01
Distinguishing quark-initiated from gluon-initiated jets is useful for many measurements and searches at the LHC. We present a quark-initiated versus gluon-initiated jet tagger from the ATLAS experiment using the number of reconstructed charged particles inside the jet. The measurement of the charged-particle multiplicity inside jets from Run 1 is used to derive uncertainties on the tagger performance for Run 2. With an efficiency of 60% to select quark-initiated jets, the efficiency to select gluon-initiated jets is between 10 and 20% across a wide range in jet pT up to 1.5 TeV with about an absolute 5% systematic uncertainty on the efficiencies. In addition, we also present preliminary studies on a tagger for the ATLAS experiment using the full radiation pattern inside a jet processed as images in deep neural network classifiers.
The heavy top quark and supersymmetry
International Nuclear Information System (INIS)
Hall, L.J.; Univ. of California, Berkeley, CA
1996-01-01
Three aspects of supersymmetric theories are discussed: electroweak symmetry breaking, the issues of flavor, and gauge unification. The heavy top quark plays an important, sometimes dominant, role in each case. Additional symmetries lead to extensions of the standard model which can provide an understanding for many of the outstanding problems of particle physics. A broken supersymmetric extension of spacetime allows electroweak symmetry breaking to follow from the dynamics of the heavy top quark; an extension of isospin provides a constrained framework for understanding the pattern of quark and lepton masses; and a grand unified extension of the standard model gauge group provides an elegant understanding of the gauge quantum numbers of the components of a generation. Experimental signatures for each of these additional symmetries are discussed
The heavy top quark and supersymmetry
International Nuclear Information System (INIS)
Hall, L.J.
1997-01-01
Three aspects of supersymmetric theories are discussed: electroweak symmetry breaking, the issues of flavor, and gauge unification. The heavy top quark plays an important, sometimes dominant, role in each case. Additional symmetries lead to extensions of the Standard Model which can provide an understanding for many of the outstanding problems of particle physics. A broken supersymmetric extension of spacetime allows electroweak symmetry breaking to follow from the dynamics of the heavy top quark; an extension of isospin provides a constrained framework for understanding the pattern of quark and lepton masses; and a grand unified extension of the Standard Model gauge group provides an elegant understanding of the gauge quantum numbers of the components of a generation. Experimental signatures for each of these additional symmetries are discussed
International Nuclear Information System (INIS)
Benenson, G.; Chau, L.L.; Ludlam, T.; Paige, F.E.; Platner, E.D.; Protopopescu, S.D.; Rehak, P.
1983-01-01
In this exercise we examine the performance of a detector specifically configured to tag heavy quark (HQ) jets through direct observations of D-meson decays with a high resolution vertex detector. To optimize the performance of such a detector, we assume the small diamond beam crossing configuration as described in the 1978 ISABELLE proposal, giving a luminosity of 10 32 cm -2 sec -1 . Because of the very large backgrounds from light quark (LQ) jets, most triggering schemes at this luminosity require high P/sub perpendicular to/ leptons and inevitably give missing neutrinos. If alternative triggering schemes could be found, then one can hope to find and calculate the mass of objects decaying to heavy quarks. A scheme using the high resolution detector will also be discussed in detail. The study was carried out with events generated by the ISAJET Monte Carlo and a computer simulation of the described detector system
Mulders, Martijn
2016-01-01
Ever since the discovery of the top quark at the Tevatron collider in 1995 the measurement of its mass has been a high priority. As one of the fundamental parameters of the Standard Theory of particle physics, the precise value of the top quark mass together with other inputs provides a test for the self-consistency of the theory, and has consequences for the stability of the Higgs field that permeates the Universe. In this review I will briefly summarize the experimental techniques used at the Tevatron and the LHC experiments throughout the years to measure the top quark mass with ever improving accuracy, and highlight the recent progress in combining all measurements in a single world average combination. As experimental measurements became more precise, the question of their theoretical interpretation has become important. The difficulty of relating the measured quantity to the fundamental top mass parameter has inspired alternative measurement methods that extract the top mass in complementary ways. I wil...
The Quark's Model and Confinement
Novozhilov, Yuri V.
1977-01-01
Quarks are elementary particles considered to be components of the proton, the neutron, and others. This article presents the quark model as a mathematical concept. Also discussed are gluons and bag models. A bibliography is included. (MA)
Heavy quarks at hadron colliders
International Nuclear Information System (INIS)
Paige, F.E.
1989-01-01
This paper discusses a conference at which the standard model requiring the existence of a top quark + to form a weak isospin doublet with the b quark is explored. Collaboration suggestions are offered. Results are explored
International Nuclear Information System (INIS)
Welke, G.M.; Heiss, W.D.
1986-01-01
In an infinite one-dimensional quark gas it is shown that a static color force, which increases at large distance, leads to a density fluctuation in the ground state. A self-consistent mean field can only be found for an effectively attractive quark-quark interaction that increases less than linearly at large distances. For a fixed coupling constant, the clustering disappears at high quark density
Energy Technology Data Exchange (ETDEWEB)
Biswas, S. N.
1980-07-01
The application of quantum statistical mechanics to a system of particles consisting of quarks is considered. Realistic theoretical investigations have been underway to understand highly dense objects such as white dwarfs and neutron stars. The various possibilities in the case of very high densities such as 10/sup 15/ or 10/sup 16/ g/cm/sup 3/ are enumerated. The thermodynamics of a phase transition from neutron matter phase to quark matter phase is analysed. Preliminary results based on quantum chromodynamics and other phenomenological models are reported.
International Nuclear Information System (INIS)
Rho, M.; CEA Centre d'Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette
1983-01-01
Some features of quark degrees of freedom in nuclei are discussed in the light of recent developments in QCD. The principal aim of this talk is to propose, and give a tentative support to, the motion that one can study through nuclear matter different facets of the vacuum structure implied by quantum chromodynamics (QCD). This will be done using the recent (exciting) results obtained in particle physics, in particular lattice gauge calculations. Relevance of this aspect of problem to quark degrees of freedom as well as meson degrees of freedom in nuclei will be discussed. (orig.)
Quark Orbital Angular Momentum
Directory of Open Access Journals (Sweden)
Burkardt Matthias
2015-01-01
Full Text Available Definitions of orbital angular momentum based on Wigner distributions are used as a framework to discuss the connection between the Ji definition of the quark orbital angular momentum and that of Jaffe and Manohar. We find that the difference between these two definitions can be interpreted as the change in the quark orbital angular momentum as it leaves the target in a DIS experiment. The mechanism responsible for that change is similar to the mechanism that causes transverse single-spin asymmetries in semi-inclusive deep-inelastic scattering.
International Nuclear Information System (INIS)
Anon.
1995-01-01
High energy heavy ion collisions have become one of the major growth areas of modern physics. Providing common ground between particle and nuclear physics, it has produced a wave of new interest and a series of major projects to provide beams of higher energies and increasing nuclear complexity. Reflecting this interest, and despite record rainstorms, over 450 enthusiastic high energy heavy ion followers met in Monterey, California, at the 11th International Conference on Ultra-relativistic Nucleus-Nucleus Collisions. Named Quark Matter '95, the meeting was characterized by its own flood of new results from experiments studying collisions of gold nuclei at the Brookhaven Alternating Gradient Synchrotron (AGS) and with silicon beams at the CERN SPS synchrotron, as well as preliminary results from the first run with lead beams at CERN late last year (December 1994, page 15). A striking aspect of the Conference was the growth in attendance and, in particular, the large number of young physicists who attended the meeting, underlining the vitality and appeal of this important field. The new preliminary data from CERN experiments NA44, NA49, NA52, WA97, and WA98, made available with remarkable speed following the initial lead beam run in November and December 1994, represent a significant step in the study of heavy ion collisions. Physicists have finally come close to conditions where it is possible to consider event-by-event analysis of these very complex final states. The importance of this emerging approach to relativistic heavy ion collisions was emphasized by Reinhard Stock (Frankfurt) and other speakers in a pre-conference workshop devoted to physics with the collider detectors at big new projects now in the pipeline - RHIC at Brookhaven and LHC at CERN. The study of collisions of heavy nuclei at relativistic energies is dominated by the search for the Quark-Gluon Plasma, the 'soup' of free quarks and gluons expected to have played an important role
A measurement of the top quark's charge
Energy Technology Data Exchange (ETDEWEB)
Unalan, Zeynep Gunay [Michigan State Univ., East Lansing, MI (United States)
2007-01-01
The top quark was discovered in 1995 at the Fermilab National Accelerator Laboratory (Fermilab). One way to confirm if the observed top quark is really the top quark posited in the Standard Model (SM) is to measure its electric charge. In the Standard Model the top quark is the isospin partner of the bottom quark and is expected to have a charge of +2/3. However, an alternative 'exotic' model has been proposed with a fourth generation exotic quark that has the same characteristics, such as mass, as our observed top but with a charge of -4/3. This thesis presents the first CDF measurement of the top quark's charge via its decay products, a W boson and a bottom quark, using ~ 1 fb^{-1} of data. The data were collected by the CDF detector from proton anti-proton (p$\\bar{p}$) collisions at √s = 1.96 TeV at Fermilab. We classify events depending on the charges of the bottom quark and associated W boson and count the number of events which appear 'SM-like' or 'exotic-like' with a SM-like event decaying as t → W^{+}b and an exotic event as t → W^{-}b. We find the p-value under the Standard Model hypothesis to be 0.35 which is consistent with the Standard Model. We exclude the exotic quark hypothesis at an 81% confidence level, for which we have chosen a priori that the probability of incorrectly rejecting the SM would be 1%. The calculated Bayes Factor (BF) is 2 x Ln(BF)=8.54 which is interpreted as the data strongly favors the Standard Model over the exotic quark hypothesis.
Possibility of stable quark stars
International Nuclear Information System (INIS)
Bowers, R.L.; Gleeson, A.M.; Pedigo, R.D.
1976-08-01
A recent zero temperature equation of state which contains quark-partons separated from conventional baryons by a phase transition is used to investigate the stability of quark stars. The sensitivity to the input physics is also considered. The conclusions, which are found to be relatively model independent, indicate that a separately identifiable class of stable objects called quark stars does not exist
PSR1987A: the case for strange-quark stars
International Nuclear Information System (INIS)
Glendenning, N.K.
1989-01-01
The new fast pulsar observed in the remnant of SN1987A, together with other considerations, provide evidence that there are two types of collapsed stars: neutron stars, having moderate central densities and subject to the usual mass constraint, and strange-quark-matter stars. We show that (i) all known pulsar masses and frequencies, with the exception of the new one, can be accounted for by plausible neutron star models; (ii) no known neutron star model can withstand the fast rotation of the new pulsar unless the central energy density is ∼ 15 that of normal nuclei, at which densities hadrons cannot plausibly exist as constituents; and (iii) if strange-quark matter is the true ground state of the strong interactions, strange-quark stars can sustain the high rotation imputed to the new pulsar. In the absence of another plausible structure that can withstand the fast rotation, we provisionally infer that the new pulsar is such a star. (author)
Quark-antiquark bound-state spectroscopy and QCD
International Nuclear Information System (INIS)
Bloom, E.D.
1982-11-01
The discussion covers quarks as we know them, the classification of ordinary mesons in terms of constituent quarks, hidden charm states and charmed mesons, bottom quarks, positronium as a model for quarti q, quantum chromodynamics and its foundation in experiment, the charmonium model, the mass of states, fine structure and hyperfine structure, classification, widths of states, rate and multipolarity of gamma transitions, questions about bottom, leptonic widths and the determination of Q/sub b/, the mass splitting of the n 3 S 1 states, the center of gravity of the masses of the n 3 P; states, n 3 P; fine structure and classification, branching ratios for upsilon' → tau chi/sub 6j/ and the tau cascade reactions, hyperfine splitting, and top
Electromagnetic moments of hadrons and quarks in a hybrid model
International Nuclear Information System (INIS)
Gerasimov, S.B.
1989-01-01
Magnetic moments of baryons are analyzed on the basis of general sum rules following from the theory of broken symmetries and quark models including the relativistic effects and hadronic corrections due to the meson exchange currents. A new sum rule is proposed for the hyperon magnetic moments, which is in accord with the most precise new data and also with a theory of the electromagnetic ΛΣ 0 mixing. The numerical values of the quark electromagnetic moments are obtained within a hybrid model treating the pion cloud effects through the local coupling of the pion field with the constituent massive quarks. Possible sensitivity of the weak neutral current magnetic moments to violation of the Okubo-Zweig-Izuki rule is emphasized nand discussed. 39 refs.; 1 fig
Quark-antiquark bound-state spectroscopy and QCD
Energy Technology Data Exchange (ETDEWEB)
Bloom, E.D.
1982-11-01
The discussion covers quarks as we know them, the classification of ordinary mesons in terms of constituent quarks, hidden charm states and charmed mesons, bottom quarks, positronium as a model for quarti q, quantum chromodynamics and its foundation in experiment, the charmonium model, the mass of states, fine structure and hyperfine structure, classification, widths of states, rate and multipolarity of gamma transitions, questions about bottom, leptonic widths and the determination of Q/sub b/, the mass splitting of the n/sup 3/S/sub 1/ states, the center of gravity of the masses of the n/sup 3/P; states, n/sup 3/ P; fine structure and classification, branching ratios for upsilon' ..-->.. tau chi/sub 6j/ and the tau cascade reactions, hyperfine splitting, and top. (GHT)
Hadronic interactions from effective chiral Lagrangians of quarks and gluons
International Nuclear Information System (INIS)
Krein, G.
1996-06-01
We discuss the combined used of the techniques of effective chiral field theory and the field theoretic method known as Fock-Tani representation to derive effective hadron interactions. The Fock-Tani method is based on a change of representation by means of a unitary transformation such that the composite hadrons are redescribed by elementary-particle field operators. Application of the unitary transformation on the microscopic quark-quark interaction derived from a chiral effective Lagrangian leads to chiral effective interactions describing all possible processes involving hadrons and their constituents. The formalism is illustrated by deriving the one-pion-exchange potential between the nucleons using the quark-gluon effective chiral Lagrangian of Manohar and Georgi. We also present the results of a study of the saturation properties of the nuclear matter using this formalism. (author). 9 refs., 2 figs
Ratios of Vector and Pseudoscalar B Meson Decay Constants in the Light-Cone Quark Model
Dhiman, Nisha; Dahiya, Harleen
2018-05-01
We study the decay constants of pseudoscalar and vector B meson in the framework of light-cone quark model. We apply the variational method to the relativistic Hamiltonian with the Gaussian-type trial wave function to obtain the values of β (scale parameter). Then with the help of known values of constituent quark masses, we obtain the numerical results for the decay constants f_P and f_V, respectively. We compare our numerical results with the existing experimental data.
Light-cone quark model with spin force for the nucleon and Δ(1232)
International Nuclear Information System (INIS)
Weber, H.J.
1992-01-01
Electromagnetic structure functions for the nucleon, static observables for the nucleon and N→D(1232) transition form factors are calculated in a relativistic constituent quark model on the light cone. The model simulates the main effect of the spin force between quarks in terms of smaller (and lighter) scalar ud diquarks in the nucleon. The polarized proton structure function is found to agree with the EMC data. (orig.)
Calculating infrared contributions to vacuum expectation values of gluonic and quark fields
International Nuclear Information System (INIS)
Arbuzov, B.A.; Boos, E.E.; Turashvili, K.Sh.
1986-01-01
Based on the infrared asymptotics of the lower QCD Green's functions obtained before, we propose a definition and elaborate a technique for calculating non-perturbative vacuum expectations of gluon and quark fields. In our calculations, we use only the known QCD parameters: constituent quark masses, the confining potential slope and the QCD parameter Λ. The values obtained for the vacuum expectations agree well with experiment. (orig.)
Quarks: Two's company, three a crowd?
International Nuclear Information System (INIS)
Anon.
1990-01-01
Last year, careful measurements by the experiments studying electron positron annihilation in CERN's new LEP ring and at Stanford's SLC linear collider showed that the conventional list of the basic constituents of matter is complete. Three types of particles (electron, muon and tau) interacting under the weak nuclear force are linked to six quarks - the constituents of nuclear matter - grouped pairwise into three distinct families ('up' and 'down', 'strange' and 'charm', 'beauty' and 'top'). The question now is to understand why this sixquark model works
Unlocking color and flavor in superconducting strange quark matter
International Nuclear Information System (INIS)
Alford, Mark; Berges, Juergen; Rajagopal, Krishna
1999-01-01
We explore the phase diagram of strongly interacting matter with massless u and d quarks as a function of the strange quark mass m s and the chemical potential μ for baryon number. Neglecting electromagnetism, we describe the different baryonic and quark matter phases at zero temperature. For quark matter, we support our model-independent arguments with a quantitative analysis of a model which uses a four-fermion interaction abstracted from single-gluon exchange. For any finite m s , at sufficiently large μ we find quark matter in a color-flavor-locked state which leaves a global vector-like SU(2) color+L+R symmetry unbroken. As a consequence, chiral symmetry is always broken in sufficiently dense quark matter. As the density is reduced, for sufficiently large m s we observe a first-order transition from the color-flavor-locked phase to color superconducting phase analogous to that in two-flavor QCD. At this unlocking transition chiral symmetry is restored. For realistic values of m s our analysis indicates that chiral symmetry breaking may be present for all densities down to those characteristic of baryonic matter. This supports the idea that quark matter and baryonic matter may be continuously connected in nature. We map the gaps at the quark Fermi surfaces in the high density color-flavor-locked phase onto gaps at the baryon Fermi surfaces at low densities
Study of stellar objects with strange quark matter crust
International Nuclear Information System (INIS)
Hothi, N.; Bisht, S.
2012-01-01
The absolute stability of strange quark matter is a viable possibility and immensely effects physics at the astrophysical scale. Relativistic heavy-ion reactions offer a stage to produce this exotic state of matter and the enhanced production of strange particles during these reactions can be studied within the framework of quark-gluon plasma (QGP). We have tried to investigate the role of strangeness under the compact star phenomenology. Emphasis is laid upon the possibility of existence of a third family of strange quark stars and its study help in revealing a number of unexplored features of the cosmos. Bag model parameters have been used to determine some integral parameters for a sequence of strange stars with crust and strange dwarfs constructed out of strange quark matter crust. A comparative analysis is performed between the strange and neutron stars and the strange and white dwarfs based upon these intrinsic parameters and paramount differences are observed. The intimacy between astrophysics and strange quarks depends strongly upon the strange quark matter hypothesis. It states that for a collection of more than a few hundred u, d and s quarks, the energy per baryon E/A of strange quark matter (SQM) can be well below the energy per baryon of the most stable atomic nuclei
Chemical Evolution of Strongly Interacting Quark-Gluon Plasma
International Nuclear Information System (INIS)
Pan, Ying-Hua; Zhang, Wei-Ning
2014-01-01
At very initial stage of relativistic heavy ion collisions a wave of quark-gluon matter is produced from the break-up of the strong color electric field and then thermalizes at a short time scale (~1 fm/c). However, the quark-gluon plasma (QGP) system is far out of chemical equilibrium, especially for the heavy quarks which are supposed to reach chemical equilibrium much late. In this paper a continuing quark production picture for strongly interacting QGP system is derived, using the quark number susceptibilities and the equation of state; both of them are from the results calculated by the Wuppertal-Budapest lattice QCD collaboration. We find that the densities of light quarks increase by 75% from the temperature T=400 MeV to T=150 MeV, while the density of strange quark annihilates by 18% in the temperature region. We also offer a discussion on how this late production of quarks affects the final charge-charge correlations
High temperature QCD with three flavors of improved staggered quarks
International Nuclear Information System (INIS)
Bernard, C.; Burch, T.; Tar, C.E. de; Gottlieb, Steven; Gregory, Eric; Heller, U.M.; Osborn, J.; Sugar, R.L.; Toussaint, D.
2003-01-01
We present an update of our study of high temperature QCD with three flavors of quarks, using a Symanzik improved gauge action and the Asqtad staggered quark action. Simulations are being carried out on lattices with N t = 4, 6 and 8 for the case of three degenerate quarks with masses less than or equal to the strange quark mass, m s and on lattices with N t = 6 and 8 for degenerate up and down quarks with masses in the range 0.2m s ≤ m u,d ≤ 0.6m s and the strange quark fixed near its physical value. We also report on first computations of quark number susceptibilities with the Asqtad action. These susceptibilities are of interest because they can be related to event-by-event fluctuations in heavy ion collision experiments. Use of the improved quark action leads to a substantial reduction in lattice artifacts. This can be seen already for free fermions and carries over into our results for QCD
International Nuclear Information System (INIS)
Rosner, J.L.
1985-10-01
New experimental and theoretical developments in heavy quark spectroscopy are reviewed. From studies of J/psi decays, the eta' is found to have some ''glue'' or other inert component, while the iota (a glueball candidate) probably contains some quarks as well. The xi(2.2) persists in new Mark III data, but is not seen by the DM2 collaboration. The production of charmonium states by anti pp reactions is reviewed. First evidence for a P- wave charmed meson, D(2420), has been presented by the ARGUS group. Radiative UPSILON decay studies fail to confirm the zeta(8.3) and begin to place useful limits on Higgs bosons. First results from an experiment at Fermilab on low-background hadronic production of UPSILON states are shown. Accurate measurements of chi/sub b/(1P) masses by the ARGUS collaboration are noted, and interpreted as favoring scalar quark confinement. Studies of t and other heavy quarks will probe the q anti q interaction below 0.05 fm, are likely to be strongly affected by t anti t-Z interference, and can provide varied information on Higgs bosons. 144 refs., 21 figs
Indian Academy of Sciences (India)
eter for the tests of the electroweak theory, since radiative corrections to many ... The uncertainty due to jet energy scale (JES) is the dominating systematic .... In the Standard Model, the charge of the top quark is predicted to be that of a normal up- ..... non-negative and f+ + f0 < 1, and the star marks the expectation from the ...
International Nuclear Information System (INIS)
Cacciari, M.
1996-08-01
The state of the art of the theoretical calculations for heavy quarks photoproduction is reviewed. The full next-to-leading order calculation and two possible resummations, the high energy one for total cross sections and the large p T one for differential cross sections, are described. (orig.)
Resinous constituent extracting process
Energy Technology Data Exchange (ETDEWEB)
Sayer, W F
1947-10-07
The method of recovering oily constituents from coal or oil shale comprising the saturation of coal or oil shale in a sealed vessel with an organic solution having a boiling point at atmospheric pressure of not exceeding 220/sup 0/C, elevating the temperature within the vessel to a temperature below the cracking temperature of the constituents and maintaining the pressure within the vessel below 51 pounds, to extract the oily material from the coal or oil shale and subsequently separating the solvent from the oily material.
International Nuclear Information System (INIS)
Deligeorges, S.
1985-01-01
After a brief recall on the classification of subatomic particles, this paper deals with quark nuggets, particle with more than three quarks, a big bag, which is called ''nuclearite''. Neutron stars, in fact, are big sacks of quarks, gigantic nuggets. Now, physicists try to calculate which type of nuggets of strange quark matter is stable, what has been the influence of quark nuggets on the primordial nucleosynthesis. At the present time, one says that if these ''nuggets'' exist, and in a large proportion, they may be candidates for the missing mass [fr
International Nuclear Information System (INIS)
Hollebeek, R.
1990-01-01
The purpose of these lectures, given at the 1989 SLAC Summer School, was to discuss the experimental aspects of heavy quark production. A companion set of lectures on the theoretical point of view were to be given by Keith Ellis. An experimentalist should gather together the measurements which have been made by various groups, compare, contrast and tabulate them, and if possible point out the ways in which these measurements confirm or contradict current theories. Here the authors has tried to do this, although the reader who expects to find here the latest of all experimental measurements should probably be forewarned that the field is moving extremely rapidly. In some cases, he has added and updated materials where crucial new information became available after or during the summer of 1989, but not in all cases. He has concentrated on trying to select those measurements which are at the moment most crucial in refining our understanding of heavy quarks as opposed to those which merely measure things which are perhaps too complicated to be enlightening at the moment. While theorists worry primarily about production mechanisms, cross sections, QCD corrections, and to some extent about signatures, the experimentalist must determine which measurements he is interested in making, and which signatures for heavy quark production are realistic and likely to produce results which will shed some new light on the underlying production model without undo theoretical complications. Experimentalists also need to evaluate the available experimental equipment, both machines and detectors to find the best way to investigate the properties of heavy quarks. In many cases, the things which we would like to measure are severely restricted by what we can measure. Nevertheless, many properties of heavy quark production and decay can be measured, and the results have already taught us much about the weak interactions and QCD
Nitta, Tatsumi; The ATLAS collaboration
2017-01-01
By colliding protons and examining particles emitted from the collisions, the Large Hadron Collider aims to study the interactions of quarks and gluons at the highest energies accessible in a controlled experimental way. In such collisions, W bosons or top quarks which have TeV scale momentum can be accessible. Reconstructing such boosted jets are becoming important. In particular, the ability to identify original particle that decays to quarks against normal QCD jets plays a central role in various searches at high energy scale. This is typically done by the use of a single physically motivated observable constructed from the constituents of the jet. In this work, multiple complementary observables are combined using boosted decision trees and neural networks to increase the ability to distinguish W bosons and top quarks from light quark jets in the ATLAS experiment.
Vector and Axial-Vector Correlators in AN Instanton-Like Quark Model
Dorokhov, Alexander E.
The behavior of the vector Adler function at spacelike momenta is studied in the framework of a covariant chiral quark model with instanton-like quark-quark interaction. This function describes the transition between the high energy asymptotically free region of almost massless current quarks to the low energy hadronized regime with massive constituent quarks. The model reproduces the Adler function and V-A correlator extracted from the ALEPH and OPAL data on hadronic τ lepton decays, transformed into the Euclidean domain via dispersion relations. The leading order contribution from hadronic part of the photon vacuum polarization to the anomalous magnetic moment of the muon, aμ hvp(1), is estimated.
Adler function and hadronic contribution to the muon g-2 in a nonlocal chiral quark model
International Nuclear Information System (INIS)
Dorokhov, Alexander E.
2004-01-01
The behavior of the vector Adler function at spacelike momenta is studied in the framework of a covariant chiral quark model with instantonlike quark-quark interaction. This function describes the transition between the high-energy asymptotically free region of almost massless current quarks to the low-energy hadronized regime with massive constituent quarks. The model reproduces the Adler function and V-A correlator extracted from the ALEPH and OPAL data on hadronic τ lepton decays, transformed into the Euclidean domain via dispersion relations. The leading order contribution from the hadronic part of the photon vacuum polarization to the anomalous magnetic moment of the muon, a μ hvp(1) , is estimated
Quark effects in nuclear physics
International Nuclear Information System (INIS)
Miller, G.A.
1983-01-01
A phenomenological approach which enables the size of quark effects in various nuclear processes is discussed. The principle of conservation of probability provides significant constraints on six quark wave functions. Using this approach, it is found that the low-energy proton-proton weak interaction can be explained in terms of W and Z boson exchanges between quarks. That the value of the asymptotic ratio of D to S state wave functions is influenced (at the 5% level) by quark effects, is another result of our approach. We have not discovered a nuclear effect that can be uniquely explained by quark-quark interactions. However it does seem that quark physics is very relevant for nuclear physics. 52 references
The A=3 Nolen-Schiffer anomaly and the up-down quark mass difference
International Nuclear Information System (INIS)
Encinosa, M.; Robson, D.
1990-01-01
A recently proposed nonrelativistic many-body quark model is used to generate class III nucleon-nucleon potentials in a Born-Oppenheimer approach. These potentials, when treated in first-order perturbation theory with a simple ansatz for the three-nucleon wave function, allow us to make an estimate of the 3 He- 3 H mass difference. For accepted values of the constituent up-down quark mass difference we find that approximately sixty percent of the A=3 Nolen-Schiffer anomaly can be accounted for solely from the up-down quark kinetic energy difference. (orig.)
Nuclei with exotic constituents
International Nuclear Information System (INIS)
Yamazaki, Toshimitsu.
1990-08-01
We discuss various interesting features in the behavior of exotic constituents of nuclei such as hyperons and mesons, in particular, with emphases on the aspect of exotic halos which are formed in general by short-range repulsion and long-range attraction. Specifically, Λ and Σ hypernuclei and pionic nuclei are discussed. (author)
Constituents of Chondria armata
Digital Repository Service at National Institute of Oceanography (India)
Govenkar, M.B.; Wahidullah, S.
A novel long chain fatty ester, pentyl hentriacontanoate 1 and an orange red pigment, caulerpin 2 have been isolated and characterised from a red alga Chondria armata. The pigment caulerpin hitherto known to be a constituent of green algae of genus...
arXiv Top Quark Mass Measurements at the LHC
AUTHOR|(INSPIRE)INSPIRE-00220136
2016-01-01
The top quark mass ($m_{top}$) is a fundamental parameter of the Standard Model of Particle Physics (SM). As the heaviest of all SM particles with a mass close to the electroweak symmetry-breaking scale, the top quark plays a pivotal role in the theory of elementary particles. The exact value of the top quark mass has implications on a number of theoretical predictions, which motivates the need for precision measurements of $m_{top}$. This document highlights a number of such measurements carried out by the ATLAS and CMS collaborations based on the combined LHC Run 1 datasets at centre-of-mass energies of $\\sqrt{s}=7$ and $8$ TeV. A wide range of analysis strategies are employed for a number of final-state signatures. Measurements of both the top quark pole mass as well as the value of $m_{top}$ as defined by the Monte Carlo generator in simulated signal samples are discussed.
Non-leptonic decays in an extended chiral quark model
Energy Technology Data Exchange (ETDEWEB)
Eeg, J. O. [Dept. of Physics, Univ. of Oslo, P.O. Box 1048 Blindern, N-0316 Oslo (Norway)
2012-10-23
We consider the color suppressed (nonfactorizable) amplitude for the decay mode B{sub d}{sup 0}{yields}{pi}{sup 0}{pi}{sup 0}. We treat the b-quark in the heavy quark limit and the energetic light (u,d,s) quarks within a variant of Large Energy Effective Theory combined with an extension of chiral quark models. Our calculated amplitude for B{sub d}{sup 0}{yields}{pi}{sup 0}{pi}{sup 0} is suppressed by a factor of order {Lambda}{sub QCD}/m{sub b} with respect to the factorized amplitude, as it should according to QCD-factorization. Further, for reasonable values of the (model dependent) gluon condensate and the constituent quark mass, the calculated nonfactorizable amplitude for B{sub d}{sup 0}{yields}{pi}{sup 0}{pi}{sup 0} can easily accomodate the experimental value. Unfortunately, the color suppressed amplitude is very sensitive to the values of these model dependent parameters. Therefore fine-tuning is necessary in order to obtain an amplitude compatible with the experimental result for B{sub d}{sup 0}{yields}{pi}{sup 0}{pi}{sup 0}.
More about unphysical zeroes in quark mass matrices
Energy Technology Data Exchange (ETDEWEB)
Emmanuel-Costa, David, E-mail: david.costa@tecnico.ulisboa.pt [Departamento de Física and Centro de Física Teórica de Partículas - CFTP, Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais, 1049-001 Lisboa (Portugal); González Felipe, Ricardo, E-mail: ricardo.felipe@tecnico.ulisboa.pt [Departamento de Física and Centro de Física Teórica de Partículas - CFTP, Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais, 1049-001 Lisboa (Portugal); ISEL - Instituto Superior de Engenharia de Lisboa, Instituto Politécnico de Lisboa, Rua Conselheiro Emídio Navarro, 1959-007 Lisboa (Portugal)
2017-01-10
We look for all weak bases that lead to texture zeroes in the quark mass matrices and contain a minimal number of parameters in the framework of the standard model. Since there are ten physical observables, namely, six nonvanishing quark masses, three mixing angles and one CP phase, the maximum number of texture zeroes in both quark sectors is altogether nine. The nine zero entries can only be distributed between the up- and down-quark sectors in matrix pairs with six and three texture zeroes or five and four texture zeroes. In the weak basis where a quark mass matrix is nonsingular and has six zeroes in one sector, we find that there are 54 matrices with three zeroes in the other sector, obtainable through right-handed weak basis transformations. It is also found that all pairs composed of a nonsingular matrix with five zeroes and a nonsingular and nondecoupled matrix with four zeroes simply correspond to a weak basis choice. Without any further assumptions, none of these pairs of up- and down-quark mass matrices has physical content. It is shown that all non-weak-basis pairs of quark mass matrices that contain nine zeroes are not compatible with current experimental data. The particular case of the so-called nearest-neighbour-interaction pattern is also discussed.
Study of dibaryon states containing three different types of quarks
International Nuclear Information System (INIS)
Leandri, J.; Silvestre-Brac, B.
1997-01-01
Previously we have shown, in a simple chromomagnetic model, that including heavy quarks in the dibaryon sector can lead to favorable configurations for stability against decay into two baryons. In this study we investigate a reduced set of favorable candidates that have emerged from our previous works. We use a non-relativistic quark model with quarks interacting through a QCD-inspired potential, which has been tested previously in meson and baryon spectroscopy. A variational procedure is performed using a great number of Gaussian functions containing all the possibilities for colour, isospin, and spin components. (author)
The spin and flavor content of intrinsic sea quarks
International Nuclear Information System (INIS)
Bo-Qiang Ma; Brodsky, S.J.
1997-07-01
The intrinsic quark-antiquark pairs generated by the minimal energy nonperturbative meson-baryon fluctuations in the nucleon sea provide a consistent framework for understanding a number of empirical anomalies observed in the deep inelastic quark-parton structure of nucleons: the flavor asymmetry of the nucleon sea implied by the violation of Gottfried sum rule, the proton spin problem implied by the violation of the Ellis-Jaffe sum rule, and the outstanding conflict between two different determinations of the strange quark sea in the nucleon
Nucleon quark distributions in a covariant quark-diquark model
Energy Technology Data Exchange (ETDEWEB)
Cloet, I.C. [Special Research Centre for the Subatomic Structure of Matter and Department of Physics and Mathematical Physics, University of Adelaide, SA 5005 (Australia) and Jefferson Lab, 12000 Jefferson Avenue, Newport News, VA 23606 (United States)]. E-mail: icloet@physics.adelaide.edu.au; Bentz, W. [Department of Physics, School of Science, Tokai University, Hiratsuka-shi, Kanagawa 259-1292 (Japan)]. E-mail: bentz@keyaki.cc.u-tokai.ac.jp; Thomas, A.W. [Jefferson Lab, 12000 Jefferson Avenue, Newport News, VA 23606 (United States)]. E-mail: awthomas@jlab.org
2005-08-18
Spin-dependent and spin-independent quark light-cone momentum distributions and structure functions are calculated for the nucleon. We utilize a modified Nambu-Jona-Lasinio model in which confinement is simulated by eliminating unphysical thresholds for nucleon decay into quarks. The nucleon bound state is obtained by solving the Faddeev equation in the quark-diquark approximation, where both scalar and axial-vector diquark channels are included. We find excellent agreement between our model results and empirical data.
Prediction of new Quarks, Generations & low Mass Quarks
Lach, Theodore
2003-04-01
The CBM (model) of the nucleus has resulted in the prediction of two new quarks, an "up" quark of mass 237.31 MeV/c2 and a "dn" quark of mass 42.392 MeV/c2. These two new predicted quarks helped to determine that the masses of the quarks and leptons are all related by a geometric progression relationship. The mass of each quark or lepton is just the "geometric mean" of two related elementary particles, either in the same generation or in the same family. This numerology predicts the following masses for the electron family: 0.511000 (electron), 7.74 (predicted), 117.3, 1778.4 (tau), 26950.1 MeV. The geometric ratio of this progression is 15.154 (e to the power e). The mass of the tau in this theory agrees very well with accepted values. This theory suggests that all the "dn like" quarks have a mass of just 10X multiples of 4.24 MeV (the mass of the "d" quark). The first 3 "up like" quark masses are 38, 237.31 and 1500 MeV. This theory also predicts a new heavy generation with a lepton mass of 27 GeV, a "dn like" quark of 42.4 GeV, and an "up like" quark of 65 GeV. Significant evidence already exists for the existence of these new quarks, and lepton. Ref. Masses of the Sub-Nuclear Particles, nucl-th/ 0008026, @ http://xxx.lanl.gov. Infinite Energy, Vol 5, issue 30.
1990-01-01
This volume contains 14 review articles on the theory and phenomenology of the creation and diagnosis of quark-gluon plasma. They are written by active investigators of in the various research topics, which range from the QCD foundation through transport theory and thermalization models to the examination of possible signatures. The monograph should be useful not only to the experienced researchers in the subject but also to newcomers.
Wood, Barry
2018-01-01
The value of Tyler Volk’s Quarks to Culture is evident when the book is placed against popular histories of the universe, dozens of which have provided evidence for an immense cosmic past. But such histories are often anecdotal, like early British histories of the kings of England. Unlike these works, Volk artfully presents the case for structural continuity and systematic creativity across 13.8 billion years of cosmic history.
International Nuclear Information System (INIS)
Paschos, E.A.
1976-08-01
The quark parton model describes the inclusive electro- and neutrino production data if a clear distinction is made between reactions which take place at high and at low energies. For the low energy region the classical view of six structure functions of the proton is still adequate. For the high energy region models can be constructed which are consistent with the experimental data. (BJ) [de
Nayak, Tapan; Sarkar, Sourav
2014-01-01
At extremely high temperatures and densities, protons and neutrons may dissolve into a "soup" of quarks and gluons, called the Quark-Gluon Plasma (QGP). For a few microseconds, shortly after the Big Bang, the Universe was filled with the QGP matter. The search and study of Quark-Gluon Plasma (QGP) is one of the most fundamental research topics of our times. The QGP matter has been probed by colliding heavy ions at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory, New York and the Large Hadron Collider at CERN, Geneva. By colliding heavy-ions at a speed close to that of light, scientists aim to obtain - albeit over a tiny volume of the size of a nucleus and for an infinitesimally short instant - a QGP state. This QGP state can be observed by dedicated experiments, as it reverts to hadronic matter through expansion and cooling. This volume presents some of the current theoretical and experimental understandings in the field of QGP.
Fields, symmetries, and quarks
International Nuclear Information System (INIS)
Mosel, U.
1989-01-01
'Fields, symmetries, and quarks' covers elements of quantum field theory, symmetries, gauge field theories and phenomenological descriptions of hadrons, with special emphasis on topics relevant to nuclear physics. It is aimed at nuclear physicists in general and at scientists who need a working knowledge of field theory, symmetry principles of elementary particles and their interactions and the quark structure of hadrons. The book starts out with an elementary introduction into classical field theory and its quantization. As gauge field theories require a working knowledge of global symmetries in field theories this topic is then discussed in detail. The following part is concerned with the general structure of gauge field theories and contains a thorough discussion of the still less widely known features of Non-Abelian gauge field theories. Quantum Chromodynamics (QCD), which is important for the understanding of hadronic matter, is discussed in the next section together with the quark compositions of hadrons. The last two chapters give a detailed discussion of phenomenological bag-models. The MIT bag is discussed, so that all theoretical calculations can be followed step by step. Since in all other bag-models the calculational methods and steps are essentially identical, this chapter should enable the reader to actually perform such calculations unaided. A last chapter finally discusses the topological bag-models which have become quite popular over the last few years. (orig.)
Transversity quark distributions in a covariant quark-diquark model
Energy Technology Data Exchange (ETDEWEB)
Cloet, I.C. [Physics Division, Argonne National Laboratory, Argonne, IL 60439-4843 (United States)], E-mail: icloet@anl.gov; Bentz, W. [Department of Physics, School of Science, Tokai University, Hiratsuka-shi, Kanagawa 259-1292 (Japan)], E-mail: bentz@keyaki.cc.u-tokai.ac.jp; Thomas, A.W. [Jefferson Lab, 12000 Jefferson Avenue, Newport News, VA 23606 (United States); College of William and Mary, Williamsburg, VA 23187 (United States)], E-mail: awthomas@jlab.org
2008-01-17
Transversity quark light-cone momentum distributions are calculated for the nucleon. We utilize a modified Nambu-Jona-Lasinio model in which confinement is simulated by eliminating unphysical thresholds for nucleon decay into quarks. The nucleon bound state is obtained by solving the relativistic Faddeev equation in the quark-diquark approximation, where both scalar and axial-vector diquark channels are included. Particular attention is paid to comparing our results with the recent experimental extraction of the transversity distributions by Anselmino et al. We also compare our transversity results with earlier spin-independent and helicity quark distributions calculated in the same approach.
Quark core stars, quark stars and strange stars
International Nuclear Information System (INIS)
Grassi, F.
1988-01-01
A recent one flavor quark matter equation of state is generalized to several flavors. It is shown that quarks undergo a first order phase transition. In addition, this equation of state depends on just one parameter in the two flavor case, two parameters in the three flavor case, and these parameters are constrained by phenomenology. This equation of state is then applied to the hadron-quark transition in neutron stars and the determination of quark star stability, the investigation of strange matter stability and possible strange star existence. 43 refs., 6 figs
Top quark pair production and top quark properties at CDF
Energy Technology Data Exchange (ETDEWEB)
Moon, Chang-Seong [INFN, Pisa
2016-06-02
We present the most recent measurements of top quark pairs production and top quark properties in proton-antiproton collisions with center-of-mass energy of 1.96 TeV using CDF II detector at the Tevatron. The combination of top pair production cross section measurements and the direct measurement of top quark width are reported. The test of Standard Model predictions for top quark decaying into $b$-quarks, performed by measuring the ratio $R$ between the top quark branching fraction to $b$-quark and the branching fraction to any type of down quark is shown. The extraction of the CKM matrix element $|V_{tb}|$ from the ratio $R$ is discussed. We also present the latest measurements on the forward-backward asymmetry ($A_{FB}$) in top anti-top quark production. With the full CDF Run II data set, the measurements are performed in top anti-top decaying to final states that contain one or two charged leptons (electrons or muons). In addition, we combine the results of the leptonic forward-backward asymmetry in $t\\bar t$ system between the two final states. All the results show deviations from the next-to-leading order (NLO) standard model (SM) calculation.
A Study of charm quark production in beauty quark decays with the OPAL detector at LEP
Waller, David
2003-01-01
The production of charm quarks in beauty quark decays has been studied with the OPAL detector at the Large Electron Positron collider near Geneva, Switzerland. The branching ratio Br(b -1 DDX) has been measured using hadronic zo decays collected between 1993 and 1995. Here b refers to the admixture of weakly decaying hadrons containing ab quark that are produced in electron-positron annihilations at a centre of mass energy equal to the mass of the zo boson. The impact parameter significance of tracks in tagged b-jets is used to differentiate b -1 DDX decays from other decays. The result is Br(b -1 DDX) = (10.0 ± 3.2(stat.)~~:~(syst. det.)~~~04 (syst. phys.))%. where syst. det. is the systematic uncertainty due to the modelling of the detector, and syst. phys. is the systematic uncertainty due to the modelling of the underlying particle physics. Using this result, the average number of charm and anti-charm quarks produced in a beauty quark decay, nc, is found to be l.12~8:i6- Ill
Chemical constituents of Asparagus
Negi, J. S.; Singh, P.; Joshi, G. P.; Rawat, M. S.; Bisht, V. K.
2010-01-01
Asparagus species (family Liliaceae) are medicinal plants of temperate Himalayas. They possess a variety of biological properties, such as being antioxidants, immunostimulants, anti-inflammatory, antihepatotoxic, antibacterial, antioxytocic, and reproductive agents. The article briefly reviews the isolated chemical constituents and the biological activities of the plant species. The structural formula of isolated compounds and their distribution in the species studied are also given. PMID:22228964
Inorganic Constituents in Coal
Directory of Open Access Journals (Sweden)
Rađenović A.
2006-02-01
Full Text Available Coal contains not only organic matter but also small amounts of inorganic constituents. More thanone hundred different minerals and virtually every element in the periodic table have been foundin coal. Commonly found group minerals in coal are: major (quartz, pyrite, clays and carbonates,minor, and trace minerals. Coal includes a lot of elements of low mass fraction of the orderof w=0.01 or 0.001 %. They are trace elements connected with organic matter or minerals comprisedin coal. The fractions of trace elements usually decrease when the rank of coal increases.Fractions of the inorganic elements are different, depending on the coal bed and basin. A varietyof analytical methods and techniques can be used to determine the mass fractions, mode ofoccurrence, and distribution of organic constituents in coal. There are many different instrumentalmethods for analysis of coal and coal products but atomic absorption spectroscopy – AAS is theone most commonly used. Fraction and mode of occurrence are one of the main factors that haveinfluence on transformation and separation of inorganic constituents during coal conversion.Coal, as an important world energy source and component for non-fuels usage, will be continuouslyand widely used in the future due to its relatively abundant reserves. However, there is aconflict between the requirements for increased use of coal on the one hand and less pollution onthe other. It’s known that the environmental impacts, due to either coal mining or coal usage, canbe: air, water and land pollution. Although, minor components, inorganic constituents can exert asignificant influence on the economic value, utilization, and environmental impact of the coal.
Nonequilibrium quark production in the expanding QCD plasma
Tanji, Naoto; Berges, Jürgen
2018-02-01
We perform real-time lattice simulations of nonequilibrium quark production in the longitudinally expanding QCD plasma. Starting from a highly occupied gluonic state with vacuum quark sector, we extract the time evolution of quark and gluon number densities per unit transverse area and rapidity. The total quark number shows after an initial rapid increase an almost linear growth with time. Remarkably, this growth rate appears to be consistent with a simple kinetic theory estimate involving only two-to-two scattering processes in small-angle approximation. This extends previous findings about the role of two-to-two scatterings for purely gluonic dynamics in accordance with the early stages of the bottom-up thermalization scenario.
The Quark-Gluon Plasma Collective Dynamics and Hard Thermal Loops
Blaizot, J P; Blaizot, Jean-Paul; Iancu, Edmond
2002-01-01
We present a unified description of the high temperature phase of QCD, the so-called quark-gluon plasma, in a regime where the effective gauge coupling $g$ is sufficiently small to allow for weak coupling calculations. The main focuss is the construction of the effective theory for the collective excitations which develop at a typical scale $gT$, which is well separated from the typical energy of single particle excitations which is the temperature $T$. We show that the plasma particles provide a source for long wavelength oscillations of average fields which carry the quantum numbers of the plasma constituents, the quarks and the gluons. To leading order in $g$, the plasma particles obey simple gauge-covariant kinetic equations, whose derivation from the general Dyson-Schwinger equations is outlined. As a by-product, the ``hard thermal loops'' emerge naturally in a physically transparent framework. We show that the collective excitations can be described in terms of classical fields, and develop for these a ...
Infrared slavery and quark confinement
Alabiso, C
1976-01-01
The question is considered of whether the so-called infrared slavery mechanism as, e.g., being manifest in non-Abelian gauge theories, necessarily confines quarks. Making a specific ansatz for the long- range forces, the Schwinger-Dyson equation is solved for the quark Green function. Besides having a confining solution, it appears that quarks may by-pass the long-range forces and be produced. (20 refs).
Infrared slavery and quark confinement
International Nuclear Information System (INIS)
Alabiso, C.; Schierholz, G.
1976-01-01
The question of whether the so-called infrared slavery mechanism as, e.g., being manifest in non-Abelian gauge theories, necessarily confines quarks is posed. Making a specific ansatz for the long-range forces, the Schwinger-Dyson equation is solved for the quark Green function. Besides having a confining solution, it appears that quarks may by-pass the long-range forces and be produced. (Auth.)
Exotic Signals of Vectorlike Quarks
Energy Technology Data Exchange (ETDEWEB)
Dobrescu, Bogdan A. [Fermilab; Yu, Felix [U. Mainz, PRISMA
2016-12-06
Vectorlike fermions are an important target for hadron collider searches. We show that the vectorlike quarks may predominantly decay via higher-dimensional operators into a quark plus a couple of other Standard Model fermions. Pair production of vectorlike quarks of charge 2/3 at the LHC would then lead to a variety of possible final states, including $t\\bar t + 4\\tau$, $t\\bar b\
Phenomenology of heavy quark systems
International Nuclear Information System (INIS)
Gilman, F.J.
1987-03-01
The spectroscopy of heavy quark systems is examined with regards to spin independent and spin dependent potentials. It is shown that a qualitative picture exists of the spin-independent forces, and that a semi-quantitative understanding exists for the spin-dependent effects. A brief review is then given of the subject of the decays of hadrons containing heavy quarks, including weak decays at the quark level, and describing corrections to the spectator model
Quark matter or new particles?
Michel, F. Curtis
1988-01-01
It has been argued that compression of nuclear matter to somewhat higher densities may lead to the formation of stable quark matter. A plausible alternative, which leads to radically new astrophysical scenarios, is that the stability of quark matter simply represents the stability of new particles compounded of quarks. A specific example is the SU(3)-symmetric version of the alpha particle, composed of spin-zero pairs of each of the baryon octet (an 'octet' particle).
International Nuclear Information System (INIS)
Zouzou, S.
1986-01-01
In the framework of simple non-relativistic potential models, we examine the system consisting of two quarks and two antiquarks with equal or unequal masses. We search for possible bound states below the threshold for the spontaneous dissociation into two mesons. We solve the four body problem by empirical or systematic variational methods and we include the virtual meson-meson components of the wave function. With standard two-body potentials, there is no proliferation of multiquarks. With unequal quark masses, we obtain however exotic (anti Qanti Qqq) bound states with a baryonic antidiquark-quark-quark structure very analogous to the heavy flavoured (Q'qq) baryons. (orig.)
Pions, delta's and quarks in nuclei
International Nuclear Information System (INIS)
Laget, J.M.
1983-10-01
Nuclear Physics has now evolved from the study of the many nucleon problem, to the study of the interplay of the degrees of freedom of such a complex system and the internal degrees of freedom of each of its hadronic constituents. Extensive studies of electronuclear reactions have all allowed us to disentangle the basic mechanisms of the interaction between two baryons in a nucleus. The pion exchange mechanisms, which dominates at large distance has been singled out. The NΔ interaction, which enter the description of the intermediate range part, has been studied. Evidences for effects due to the quark structure of the nucleon have been found. But more systematic studies are needed to study them in detail
From nucleons to quarks in nuclei
International Nuclear Information System (INIS)
Laget, J.M.
1984-07-01
Nuclear Physics has now evolved from the study of the many nucleon problem, to the study of the interplay of the degrees of freedom of such a complex system and the internal degrees of freedom of each of its hadronic constituents. Extensive studies of electronuclear reactions have allowed us to disentangle the basic mechanisms of the interaction between two baryons in a nucleus. The pion exchange mechanism, which dominates at large distance has been singled out. The NΔ interaction, which enter the description of the intermediate range part, has been studied. Evidences for effects due to the quark structure of the nucleon have been found. They involve the short distance structure of the nucleus
Hadron production at RHIC: recombination of quarks
Energy Technology Data Exchange (ETDEWEB)
Fries, Rainer J [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States)
2005-01-01
We discuss quark recombination applied to the hadronization of a quark gluon plasma. It has been shown that the quark recombination model can explain essential features of hadron production measured in high energy heavy ion collisions.
Cold quark matter in compact stars
Energy Technology Data Exchange (ETDEWEB)
Franzon, B.; Fogaca, D. A.; Navarra, F. S. [Instituto de Fisica, Universidade de Sao Paulo Rua do Matao, Travessa R, 187, 05508-090 Sao Paulo, SP (Brazil); Horvath, J. E. [Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo, Rua do Matao, 1226, 05508-090, Sao Paulo, SP (Brazil)
2013-03-25
We used an equation of state for the cold quark matter to the study of properties of quark stars. We also discuss the absolute stability of quark matter and compute the mass-radius relation for self-bound stars.
Models of quark bags and their consequences
International Nuclear Information System (INIS)
Bogolubov, P.N.
1977-01-01
The development of the first Dubna Quark Bag and the results obtained in this way are considered. The idea of the first Dubna Quark Bag is as follows: baryons are constructed of three quarks measons are constructed of two quarks, and each quark is interpreted as the Dirac particle which moves in a scalar square well. The so-called quasiindependent quark model is considered too. It is a simple quark model based on an analogy with the shell model for nuclei. The quarks are considered as moving in an arbitrary radially-symmetric field, and their one-particle wave function satisfies the usual Dirac equation. Such quark model can give at least the same results as the relativistic bag model. A possibility exists to improve the results of the relativistic quark model with the oscillator interaction between quarks. The results of the MIT-Bag model and the quasiindependent quark model coincide
A gentilionic approach to quark colours
International Nuclear Information System (INIS)
Cattani, M.S.D.; Fernandes, N.C.
1984-01-01
An extended form of Noether's theorem enable us to identify the colour quantum number with the eigenvalue of the invariant of the algebra of S sup((3)). In the gentilionic approach, the composition of the S sup((3)) colour with the symmetric quark model seems to constitute an exact symmetry of Nature. It is also argued some general properties and the universality of Gentile statistics. (Author) [pt
A gentilion hypothesis for quark colours
International Nuclear Information System (INIS)
Cattani, M.S.D.; Fernandes, N.C.
1984-01-01
Extendind the Noether's theorem it is possible to identify the colour quantum numbers with the eigenvalue of a S sup((3)) algebra invariant. In the gentilion approximation, the composition of the coloured S sup((3)) with the symmetric quark model seems to constitute in an exact symmetry of the nature. Some general properties related with the observationality in Quantum Mechanics are also approached and the Gentile statistical universality is asserted. (L.C.) [pt
Effective field theory and the quark model
International Nuclear Information System (INIS)
Durand, Loyal; Ha, Phuoc; Jaczko, Gregory
2001-01-01
We analyze the connections between the quark model (QM) and the description of hadrons in the low-momentum limit of heavy-baryon effective field theory in QCD. By using a three-flavor-index representation for the effective baryon fields, we show that the 'nonrelativistic' constituent QM for baryon masses and moments is completely equivalent through O(m s ) to a parametrization of the relativistic field theory in a general spin-flavor basis. The flavor and spin variables can be identified with those of effective valence quarks. Conversely, the spin-flavor description clarifies the structure and dynamical interpretation of the chiral expansion in effective field theory, and provides a direct connection between the field theory and the semirelativistic models for hadrons used in successful dynamical calculations. This allows dynamical information to be incorporated directly into the chiral expansion. We find, for example, that the striking success of the additive QM for baryon magnetic moments is a consequence of the relative smallness of the non-additive spin-dependent corrections
Quark and Gluon Relaxation in Quark-Gluon Plasmas
Heiselberg, H.; Pethick, C. J.
1993-01-01
The quasiparticle decay rates for quarks and gluons in quark-gluon plasmas are calculated by solving the kinetic equation. Introducing an infrared cutoff to allow for nonperturbative effects, we evaluate the quasiparticle lifetime at momenta greater than the inverse Debye screening length to leading order in the coupling constant.
The discovery of the top quark
International Nuclear Information System (INIS)
Sinervo, P.K.
1995-12-01
The top quark and the Higgs boson are the heaviest elementary particles predicted by the standard model. The four lightest quark flavours, the up, down, strange and charm quarks, were well-established by the mid-1970's. The discovery in 1977 of the Τ resonances, a new family of massive hadrons, required the introduction of the fifth quark flavour. Experimental and theoretical studies have indicated that this quark also has a heavier partner, the top quark
The Discovery of the Top Quark
Sinervo, P.K.
1995-12-01
The top quark and the Higgs boson are the heaviest elementary particles predicted by the standard model. The four lightest quark flavours, the up, down, strange and charm quarks, were well-established by the mid-1970's. The discovery in 1977 of the {Tau} resonances, a new family of massive hadrons, required the introduction of the fifth quark flavour. Experimental and theoretical studies have indicated that this quark also has a heavier partner, the top quark.
Energy Technology Data Exchange (ETDEWEB)
Otterlund, Ingvar; Ruuskanen, Vesa
1993-12-15
In his welcome address to the 10th International Conference on Ultra- Relativistic Nucleus-Nucleus Collisions (Quark Matter '93), held in Borlange, Sweden, from 20-24 June, Hans-Ake Gustafsson was puzzled why this year's conference was billed as the tenth in the series. He had tried to count but could only find eight forerunners - Bielefeld (1982), Brookhaven (1983), Helsinki (1984), Asilomar (1986), Nordkirchen (1987), Lenox (1988), Menton (1990), Gatlinburg (1991), making this year's meeting at Borlange the ninth. The answer was given by Helmut Satz in his introductory talk, pointing out that at the time of the Bielefeld meeting, a few conferences dealing with similar topics had already been held. The Bielefeld organizers thus did not consider their conference the first. Whatever its pedigree, the Borlange meeting covered particle production in highly excited and compressed nuclear matter, fluctuations and correlations, quark phenomena (quantum chromodynamics - QCD) in nuclear collisions, probes and signatures of Quark-Gluon Plasma (QGP), future collider experiments and instrumentation. The theoretical talks were split between the fundamental properties of the hot and dense matter at or near equilibrium, and the interface between theory and experiment. The phenomenological modelling of heavy ion collisions seems to reproduce at least all the main features of the data with hadrons, resonances and strings as the degrees of freedom. However secondary interactions among the produced hadrons or strings need to be added. Hydrodynamic calculations lead to results which reproduce the main features of the collisions. With increasing collision energy, the parton degrees of freedom become more important. Klaus Geiger described an ambitious scheme treating the whole nucleus-nucleus collision in terms of a kinetic parton (quark/gluon) cascade. The initial parton distribution at the beginning of the collision is determined from the quark-gluon nuclear structure and the
International Nuclear Information System (INIS)
Otterlund, Ingvar; Ruuskanen, Vesa
1993-01-01
In his welcome address to the 10th International Conference on Ultra- Relativistic Nucleus-Nucleus Collisions (Quark Matter '93), held in Borlange, Sweden, from 20-24 June, Hans-Ake Gustafsson was puzzled why this year's conference was billed as the tenth in the series. He had tried to count but could only find eight forerunners - Bielefeld (1982), Brookhaven (1983), Helsinki (1984), Asilomar (1986), Nordkirchen (1987), Lenox (1988), Menton (1990), Gatlinburg (1991), making this year's meeting at Borlange the ninth. The answer was given by Helmut Satz in his introductory talk, pointing out that at the time of the Bielefeld meeting, a few conferences dealing with similar topics had already been held. The Bielefeld organizers thus did not consider their conference the first. Whatever its pedigree, the Borlange meeting covered particle production in highly excited and compressed nuclear matter, fluctuations and correlations, quark phenomena (quantum chromodynamics - QCD) in nuclear collisions, probes and signatures of Quark-Gluon Plasma (QGP), future collider experiments and instrumentation. The theoretical talks were split between the fundamental properties of the hot and dense matter at or near equilibrium, and the interface between theory and experiment. The phenomenological modelling of heavy ion collisions seems to reproduce at least all the main features of the data with hadrons, resonances and strings as the degrees of freedom. However secondary interactions among the produced hadrons or strings need to be added. Hydrodynamic calculations lead to results which reproduce the main features of the collisions. With increasing collision energy, the parton degrees of freedom become more important. Klaus Geiger described an ambitious scheme treating the whole nucleus-nucleus collision in terms of a kinetic parton (quark/gluon) cascade. The initial parton distribution at the beginning of the collision is determined from the quark-gluon nuclear structure
Hot nuclear matter in the modified quark-meson coupling model with quark-quark correlations
International Nuclear Information System (INIS)
Zakout, I.; Jaqaman, H.R.
2000-01-01
Short-range quark-quark correlations in hot nuclear matter are examined within the modified quark-meson coupling (MQMC) model by adding repulsive scalar and vector quark-quark interactions. Without these correlations, the bag radius increases with the baryon density. However, when the correlations are introduced the bag size shrinks as the bags overlap. Also as the strength of the scalar quark-quark correlation is increased, the decrease of the effective nucleon mass M* N with the baryonic density is slowed down and tends to saturate at high densities. Within this model we study the phase transition from the baryon-meson phase to the quark-gluon plasma (QGP) phase with the latter modelled as an ideal gas of quarks and gluons inside a bag. Two models for the QGP bag parameter are considered. In one case, the bag is taken to be medium-independent and the phase transition from the hadron phase to QGP is found to occur at five to eight times ordinary nuclear matter density for temperatures less than 60 MeV. For lower densities, the transition takes place at a higher temperature, reaching up to 130 MeV at zero density. In the second case, the QGP bag parameter is considered to be medium-dependent as in the MQMC model for the hadronic phase. In this case, it is found that the phase transition occurs at much lower densities. (author)
Quark fragmentation function and the nonlinear chiral quark model
International Nuclear Information System (INIS)
Zhu, Z.K.
1993-01-01
The scaling law of the fragmentation function has been proved in this paper. With that, we show that low-P T quark fragmentation function can be studied as a low energy physocs in the light-cone coordinate frame. We therefore use the nonlinear chiral quark model which is able to study the low energy physics under scale Λ CSB to study such a function. Meanwhile the formalism for studying the quark fragmentation function has been established. The nonlinear chiral quark model is quantized on the light-front. We then use old-fashioned perturbation theory to study the quark fragmentation function. Our first order result for such a function shows in agreement with the phenomenological model study of e + e - jet. The probability for u,d pair formation in the e + e - jet from our calculation is also in agreement with the phenomenological model results
Kurkela, Aleksi
2016-07-20
We generalize the state-of-the-art perturbative Equation of State of cold quark matter to nonzero temperatures, needed in the description of neutron star mergers and core collapse processes. The new result is accurate to order g^5 in the gauge coupling, and is based on a novel framework for dealing with the infrared sensitive soft field modes of the theory. The zero Matsubara mode sector is treated using a dimensionally reduced effective theory, while the soft non-zero modes are resummed using the Hard Thermal Loop approximation. This combination of known effective descriptions offers unprecedented access to small but nonzero temperatures, both in and out of beta equilibrium.
Manohar, A. V.
2003-02-01
These lecture notes present some of the basic ideas of heavy quark effective theory. The topics covered include the classification of states, the derivation of the HQET Lagrangian at tree level, hadron masses, meson form factors, Luke's theorem, reparameterization invariance and inclusive decays. Radiative corrections are discussed in some detail, including an explicit computation of a matching correction for HQET. Borel summability, renormalons, and their connection with the QCD perturbation series is covered, as well as the use of the upsilon expansion to improve the convergence of the perturbation series.
Hard probes (and soft ones) to test the quark-gluon soup
Preuss, Paul
2006-01-01
"We need the hardest probes of all to study the hot, dense state of matter that exists when two heavy nuclei like gold collide with enough energy to temporarily free the quarks and gluons in their constituent protons and neutrons." (3 pages)
Exactly solvable model of phase transition between hadron and quark-gluon-matter
International Nuclear Information System (INIS)
Gorenstein, M.I.; Petrov, V.K.; Shelest, V.P.; Zinovjev, G.M.
1982-01-01
An exactly solvable model of phase transition between hadron and quark-gluon matter is proposed. The hadron phase of this model is considered as a gas of bags filled by point massless constituents. The mass and volume spectrum of the bag is found. The thermodynamical characteristics of a bag gas in the neighbourhood of a phase transition point are ascertained in analytical form
On the limits of application of the nolocal quark model
International Nuclear Information System (INIS)
Efimov, G.V.; Ivanov, M.A.; Novitsyn, E.A.; Ryabtsev, A.D.
1983-01-01
The possibility of application of the nolocal quark model (NQM) to the physics of mesons, containin charmed quarks, is considered. A method for description of states with identical quantum numbers is suggested. I' order to distinguish between such states different quark currents are introduced with additional condition of ''o thogonality'' implied. The latter allows one to neglect nondiagonal off-shell matrix elements in compositeness conditi ' for coupling constants. In the framework of NQM with ditional assumptions mentioned several decay widths of vector charmonium states have been computed, namely lepton c widths of J/psi(3100), psi'(3685) and psi(3770) an the decay width into charmed D-mesons psi(3770) → D nti D. It is shown that the two-parametric freedom of the m del is not sufficient to fit the experimental data. It is co'cluded that the revision of basic concepts of NQM is nec ssary in physics of mesons containing c-quarks
Dual Ginzburg-Landau theory and quark nuclear physics
International Nuclear Information System (INIS)
Toki, Hiroshi
1999-01-01
The elementary building blocks of matter are quarks. Hence, it is fundamental to describe hadrons and nuclei in terms of quarks and gluons, the subject of which is called Quark Nuclear Physics. The quark-dynamics is described by Quantum Chromodynamics (QCD). Our interest is the non-perturbative aspect of QCD as confinement, chiral symmetry breaking, hadronization etc. We introduce the dual Ginzburg-Landau theory (DGL), where the color monopole fields and their condensation is the QCD vacuum, play essential roles in describing these non-perturbative phenomena. We emphasize its connection to QCD through the use of the Abelian gauge. We apply the DGL theory to various observables. We discuss then the connection of the monopole fields with instantons, which are the classical solutions of the non-Abelian gauge theory and connect through the tunneling process QCD vacuum with different winding numbers. (author)
Study of quark structure functions
International Nuclear Information System (INIS)
Dao, F.T.; Flaminio, E.; Lai, K.; Metcalf, M.; Wang, L.
1977-01-01
The quark structure functions of the proton are determined through a combined analysis of the reactions pN → ll-barX and eN → eX. The valence-quark structure function of the pion is also given by analyzing the πN → μμ-barX data measured by the Branson et al
Hadron interactions in quark models
International Nuclear Information System (INIS)
Narodetskij, I.M.
1987-01-01
Some recent developments on the study of quark degrees of freedom in hadron scattering at intermediate energy are reviewed. Physical foundations of the P-matrix approach and the Quark Compound Bag method are discussed including applications to pion-pion, pion-nucleon, nucleon-nucleon and three-nucleon systems
Quark models in hadron physics
International Nuclear Information System (INIS)
Phatak, Shashikant C.
2007-01-01
In this talk, we review the role played by the quark models in the study of interaction of strong, weak and electromagnetic probes with hadrons at intermediate and high momentum transfers. By hadrons, we mean individual nucleons as well as nuclei. We argue that at these momentum transfers, the structure of hadrons plays an important role. The hadron structure of the hadrons is because of the underlying quark structure of hadrons and therefore the quark models play an important role in determining the hadron structure. Further, the properties of hadrons are likely to change when these are placed in nuclear medium and this change should arise from the underlying quark structure. We shall consider some quark models to look into these aspects. (author)
International Nuclear Information System (INIS)
Anderson, J.T.
1994-01-01
Without the spin interactions the hardron masses within a multiplet are degenerate. The light quark hadron degenerate mulitplet mass spectrum is extended from the 3 quark ground state multiplets at J P =0 - , 1/2 + , 1 - to include the excited states which follow the spinorial decomposition of SU(2)xSU(2). The mass scales for the 4, 5, 6, .. quark hadrons are obtained from the degenerate multiplet mass m 0 /M=n 2 /α with n=4, 5, 6, .. The 4, 5, 6, .. quark hadron degenerate multiplet masses follow by splitting of the heavy quark mass scales according to the spinorial decomposition of SU(2)xSU(2). (orig.)
Quark approach to Santilli's conjecture on hadronic structure - II
International Nuclear Information System (INIS)
Animalu, A.O.E.
1982-08-01
In this paper, we continue an earlier investigation of an exactly soluble relativistic Bohr-type model of the internal structure of the proton (three-quark baryon system) and the pion (quark-antiquark meson system), based on a realization of Santilli's conjecture that the hadronic constituents are extended (non-pointlike) objects. The model is abstracted from an expansion of a Yukawa-type potential between the valence quarks and a massive core, in which the meson or gluon exchange term has the effect of reducing the effective Bohr radius for binding to a value less than the radius of the strong charge sphere (or Compton wavelength) of each constituent, so that appreciable overlap of charge volumes occurs, to within a typical distance of order 0.25F or 1/(800 MeV) in qqq-system, and order 1/(1200 MeV) in qq-bar-system, which are comparable to gluon masses, msub(G) approx.= 800 to 1200 MeV, required by the lattice QCD and the MIT Bag Model. Based on the assumptions that the ground state of the proton has 1s 2 2s valence quark configuration, the non-strange quark mass is msub(p)/3, and the dimensionless strong coupling constant of the Yukawa-type potential is g 2 =1, the mass of the proton core is determined self-consistently to be 2470 MeV, exactly balancing the quark binding energy so that the valence quarks appear free. The model correctly predicts the masses of the well-known resonant states of the proton with Jsup(P)=1/2 + as excited states associated with the configuration 1s2s 2 and predicts an upper bound (spectroscopic limit) for the mass of the excited states of the proton in ns 2 ms configuration, as n→infinity and m→infinity, to be 3409 MeV. Based on a generalization of the model to qq-bar-systems, an upper bound (spectroscopic limit) for the mass of qq-bar in ns 2 configuration, as n→infinity, is found to be 3096 MeV, which is the mass of the J/psi-meson. The relation of the model to violation of time-reversal invariance (T-symmetry) by non
International Nuclear Information System (INIS)
Schramm, D.N.; Fields, B.; Thomas, D.
1992-01-01
The possible implications of the quark-hadron transition for cosmology are explored. Possible surviving signatures are discussed. In particular, the possibility of generating a dark matter candidate such as strange nuggets or planetary mass black holes is noted. Much discussion is devoted to the possible role of the transition for cosmological nucleosynthesis. It is emphasized that even an optimized first order phase transition will not significantly alter the nucleosynthesis constraints on the cosmological baryon density nor on neutrino counting. However, it is noted that Be and B observations in old stars may eventually be able to be a signature of a cosmologically significant quark-hadron transition. It is pointed out that the critical point in this regard is whether the observed B/Be ratio can be produced by spallation processes or requires cosmological input. Spallation cannot produce a B/Be ratio below 7.6. A supporting signature would be Be and B ratios to oxygen that greatly exceed galactic values. At present, all data is still consistent with a spallagenic origin
Constituent gluon interpretation of glueballs and gluelumps
International Nuclear Information System (INIS)
Boulanger, N.; Buisseret, F.; Mathieu, V.; Semay, C.
2008-01-01
Arguments are given that support the interpretation of the lattice QCD glueball and gluelump spectra in terms of bound states of massless constituent gluons with helicity 1. In this scheme, we show that the mass hierarchy of the currently known gluelumps and glueballs is mainly due to the number of constituent gluons and can be understood within a simple flux tube model. It is also argued that the lattice QCD 0 +- glueball should be seen as a four-gluon bound state. We finally predict the mass of the 0 - state, not yet computed in lattice QCD. (orig.)
Top quark production at the LHC (single top and tt-bar cross sections)
International Nuclear Information System (INIS)
Lange, J.
2014-01-01
With the large number of top quarks produced at the LHC, top quark physics enters an era of precision and properties measurements. This article reviews the recent advances in top quark cross section measurements performed by ATLAS and CMS using data recorded in 2011 with integrated luminosities up to 5 fb -1 . They include precision inclusive cross sections, the establishment of challenging channels, first differential cross section measurements and single top production. An overall good agreement with Standard Model predictions is observed
Strange particle production from quark matter droplets
International Nuclear Information System (INIS)
Werner, K.; Hladik, M.
1995-01-01
We recently introduced new methods to study ultrarelativistic nuclear scattering by providing a link between the string model approach and a thermal description. The string model is used to provide information about fluctuations in energy density. Regions of high energy density are considered to be quark matter droplets and treated macroscopically. At SPS energies, we find mainly medium size droplets---with energies up to few tens of Gev. A key issue is the microcanonical treatment of individual quark matter droplets. Each droplet hadronizes instantaneously according to the available n-body phase space. Due to the huge number of possible hadron configurations, special Monte Carlo techniques have been developed to calculate this disintegration. We present results concerning the production of strange particles from such a hadronization as compared to string decay. copyright 1995 American Institute of Physics
The potential model of coloured quarks
International Nuclear Information System (INIS)
Greenberg, O.W.
1981-01-01
The success of the additive potential model of colored quarks for the masses, decay rates, and other properties of single mesons and baryons does not imply that this model can yield the observed meson-nucleon and nucleon-nucleon interactions. We give a comprehensive discussion of this issue. In agreement with previous authors, we conclude that, on the contrary, this model predicts inverse-power color-analog van der Waals potentials between separated hadrons which are in substantial contradiction with experimental data. We also discuss pathologies of non-abelian confining potentials, and show that the hamiltonian is unbounded below for an arbitrary number of quarks and antiquarks in a definite color state for all color states, except the singlet, triplet, and antitriplet. (orig.)
Bound-state quark and gluon contributions to structure functions in QCD
International Nuclear Information System (INIS)
Brodsky, S.J.
1990-08-01
One can distinguish two types of contributions to the quark and gluon structure functions of hadrons in quantum chromodynamics: ''intrinsic'' contributions, which are due to the direct scattering on the bound-state constituents, and ''extrinsic'' contributions, which are derived from particles created in the collision. In this talk, I discussed several aspects of deep inelastic structure functions in which the bound-state structure of the proton plays a crucial role: the properties of the intrinsic gluon distribution associated with the proton bound-state wavefunction; the separation of the quark structure function of the proton onto intrinsic ''bound-valence'' and extrinsic ''non-valence'' components which takes into account the Pauli principle; the properties and identification of intrinsic heavy quark structure functions; and a theory of shadowing and anti-shadowing of nuclear structure functions, directly related to quark-nucleon interactions and the gluon saturation phenomenon. 49 refs., 5 figs
Bound-state quark and gluon contributions to structure functions in QCD
International Nuclear Information System (INIS)
Brodsky, S.J.
1991-01-01
One can distinguish two types of contributions to the quark and gluon structure functions of hadrons in quantum chromodynamics: 'intrinsic' contributions, which are due to the direct scattering on the bound-state constituents, and 'extrinsic' contributions, which are derived from particles created in the collision. In this talk, I discuss several aspects of deep inealstic structure functions in which the bound-state structure of the proton plays a crucial role: (1) the properties of the intrinsic gluon distribution associated with the proton bound-state wavefunction; (2) the separation of the quark structure function of the proton into intrinsic 'bound-valence' and extrinsic 'non-valence' components which takes into account the Pauli principle; (3) the properties and identification of intrinsic heavy quark structure functions; and (4) a theory of shadowing and anti-shadowing of nuclear structure functions, directly related to quark-nucleon interactions and the gluon saturation phenomenon. (orig.)
Light-quark, heavy-quark systems: An update
Grinstein, B.
1993-06-01
We review many of the recently developed applications of Heavy Quark Effective Theory techniques. After a brief update on Luke's theorem, we describe striking relations between heavy baryon form factors, and how to use them to estimate the accuracy of the extraction of (vert bar)V(sub cb)(vert bar). We discuss factorization and compare with experiment. An elementary presentation, with sample applications, of reparametrization invariance comes next. The final and most extensive chapter in this review deals with phenomenological lagrangians that incorporate heavy-quark spin-flavor as well as light quark chiral symmetries. We compile many interesting results and discuss the validity of the calculations.
Light-quark, heavy-quark systems: An update
International Nuclear Information System (INIS)
Grinstein, B.
1993-01-01
The author reviews many of the recently developed applications of Heavy Quark Effective Theory techniques. After a brief update on Luke's theorm, he describes striking relations between heavy baryon form factors, and how to use them to estimate the accuracy of the extraction of |B cb |. He discusses factorization and compares with experiment. An elementary presentation, with sample applications, of reparametrization invariance comes next. The final and most extensive chapter in this review deals with phenomenological lagrangians that incorporate heavy-quark spin-flavor as well as light quark chiral symmetries. He compiles many interesting results and discuss the validity of the calculations
How the physicists nailed the quarks
International Nuclear Information System (INIS)
Anon.
1985-01-01
The paper reviews quarks, from its prediction in 1962, to the experiments confirming its existence in the 1970's and 1980's. The elementary particles of matter; building particles from quarks; why quarks can never be isolated; and the six quarks; are all discussed. (U.K.)
Heavy baryons in the relativistic quark model
International Nuclear Information System (INIS)
Ebert, D.; Faustov, R.N.; Galkin, V.O.; Martynenko, A.P.; Saleev, V.A.
1996-07-01
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 J P =1/2 + , 3/2 + are computed. (orig.)
International Nuclear Information System (INIS)
Menzione, A.
1995-10-01
Most of the material presented in this report, comes from contributions to the parallel session PL20 of this conference. We summarise the experimental results of direct production of Top quarks, coming from the CDF and C0 Collaborations at Fermilab, and compare these results to what one expects within current theoretical understanding. Particular attention is given to new results such as all hadronic modes of t bar t decay. As far as the mass is concerned, a comparison is made with precision measurements of related quantities, coming from LEP and other experiments. An attempt is made to look at the medium-term future and understand which variables and with what accuracy one can measure them with increased integrated luminosity
Quarks and numerical simulation
International Nuclear Information System (INIS)
Weingarten, D.
1996-01-01
This work deals with the quantum chromodynamics and the theory of quarks's behaviour. The experimentation supports this theory but until now no computation have prove it. The resolution of the mathematic equations were far beyond the capability of human or the quickest computer of the seventies. A dedicated computer was built: the GF11. The mass of eight hadrons was computed in 91. In 95, a new particle was found by computation. The author explains the mathematical modeling of chromodynamics and the methods to solve it. It requires 10 17 arithmetic operations. So specific computer is needed. GF11 uses 566 processors in parallel. New machines hundred of times more efficient will be needed to go further. That will be a new tool for theorician physicists. (O.M.). 9 refs., 2 figs., 1 tab
Dihadron fragmentation functions in the quark-jet model: Transversely polarized quarks
Matevosyan, Hrayr H.; Kotzinian, Aram; Thomas, Anthony W.
2018-01-01
Within the most recent extension of the quark-jet hadronization framework, we explore the transverse-polarization-dependent dihadron fragmentation functions (DiFFs) H1∢ and H1⊥ of a quark into π+π- pairs. Monte Carlo (MC) simulations are employed to model polarized quark hadronization and calculate the corresponding number densities. These, in turn, are used to extract the Fourier cosine moments of the DiFFs H1∢ and H1⊥. A notable finding is that there are previously unnoticed apparent discrepancies between the definitions of the so-called interference DiFF (IFF) H1∢ , entering the cross sections for two-hadron semi-inclusive electroproduction, and those involved in the production of two pairs of hadrons from back-to-back jets in electron-positron annihilation. This manuscript completes the studies of all four leading-twist DiFFs for unpolarized hadron pairs within the quark-jet framework, following our previous work on the helicity-dependent DiFF G1⊥.
A new parametric equation of state and quark stars
International Nuclear Information System (INIS)
Na Xuesen; Xu Renxin
2011-01-01
It is still a matter of debate to understand the equation of state of cold matter with supra-nuclear density in compact stars because of unknown non-perturbative strong interaction between quarks. Nevertheless, it is speculated from an astrophysical view point that quark clusters could form in cold quark matter due to strong coupling at realistic baryon densities. Although it is hard to calculate this conjectured matter from first principles, one can expect that the inter-cluster interaction will share some general features with the nucleon- nucleon interaction successfully depicted by various models. We adopt a two-Gaussian component soft-core potential with these general features and show that quark clusters can form stable simple cubic crystal structure if we assume that the wave function of quark clusters have a Gaussian form. With this parametrization, the Tolman-Oppenheimer-Volkoff equation is solved with reasonably constrained parameter space to give mass-radius relations of crystalline solid quark stars. With baryon number densities truncated at 2n 0 at surface and the range of the interaction fixed at 2 fm we can reproduce similar mass-radius relations to that obtained with bag model equations of state. The maximum mass ranges from ∼ 0.5 solar mass to approx.> 3 solar mass . The recently measured high pulsar mass (approx.> 2 solar mass ) is then used to constrain the parameters of this simple interaction potential. (authors)
From the top-quark to the Higgs-Boson: the search for the heaviest particles of nature
International Nuclear Information System (INIS)
Mueller, T.
2001-01-01
According to our present knowledge the fundamental constituents of matter are quarks and leptons ordered by their mass into three particle families. With the discovery of the top quark about six years age our periodic table of elementary particles has been completed but the origin of its unusually high mass and, more general, of the mass of all particles, still needs to be established. The Institut fuer Experimentelle Kernphysik in Karlsruhe, who researches on the top quark and its properties, also takes part in the world-wide race for the discovery of the widely believed mediator of mass, the Higgs boson. (orig.)
International Nuclear Information System (INIS)
Gaillard, M.K.
1978-08-01
The properties that may help to identify the two additional quark flavors that are expected to be discovered. These properties are lifetime, branching ratios, selection rules, and lepton decay spectra. It is also noted that CP violation may manifest itself more strongly in heavy particle decays than elsewhere providing a new probe of its origin. The theoretical progress in the understanding of nonleptonic transitions among lighter quarks, nonleptonic K and hyperon decay amplitudes, omega minus and charmed particle decay predictions, and lastly the Kobayashi--Maskawa model for the weak coupling of heavy quarks together with the details of its implications for topology and bottomology are treated. 48 references
Holographic lessons for quark dynamics
Chernicoff, Mariano; García, J. Antonio; Güijosa, Alberto; Pedraza, Juan F.
2012-05-01
We give a brief overview of recent results obtained through the gauge/gravity correspondence, concerning the propagation of a heavy quark in strongly coupled conformal field theories (such as {N}=4 super-Yang-Mills), both at zero and finite temperature. In the vacuum, we discuss energy loss, radiation damping, signal propagation and radiation-induced fluctuations. In the presence of a thermal plasma, our emphasis is on early-time energy loss, screening and quark-antiquark evolution after pair creation. Throughout, quark dynamics is seen to be efficiently encapsulated in the usual string worldsheet dynamics.
Energy Technology Data Exchange (ETDEWEB)
Harari, H
1976-01-01
The experimental information which was accumulated in the last 18 months in e/sup +/e/sup -/ collisions and ..nu..N scattering indicates that more than four kinds of quarks are already present. Six different pieces of evidence for the existence of six quarks: the triangle anomalies, the value of R, psi-spectroscopy, neutrino processes, CP-violation and the possible existence of V+A currents are discussed. It is concluded that there is strong (but not yet conclusive) evidence for the existence of six quarks and six leptons.
International Nuclear Information System (INIS)
Harari, Haim
The experimental information which was accumulated in the last 18 months in e + e - collisions and neutrino+N scattering indicates that more than four kinds of quarks are already present. Six different pieces of evidence for the existence of six quarks are discussed: the triangle anomalies, the value of R, psi-spectroscopy, neutrino processes, CP-violation and the possible existence of V+A currents. It is concluded that there is strong (but not yet conclusive) evidence for the existence of six quarks and six leptons
International Nuclear Information System (INIS)
Thorndike, E.H.; Poling, R.A.
1988-01-01
Recent experimental results on the decay of b-flavored hadrons are reviewed. Substantial progress has been made in the study of exclusive and inclusive B-meson decays, as well as in the theoretical understanding of these processes. The two most prominent developments are the continuing failure to observe evidence of decays of the b quark to a u quark rather than a c quark, and the surprisingly high level of B 0 -anti B 0 mixing which has recently been reported by the ARGUS collaboration. Notwithstanding these results, we conclude that the health of the Standard Model is excellent. (orig.)
Quark chiral condensate from the overlap quark propagator
Wang, Chao; Bi, Yujiang; Cai, Hao; Chen, Ying; Gong, Ming; Liu, Zhaofeng
2017-05-01
From the overlap lattice quark propagator calculated in the Landau gauge, we determine the quark chiral condensate by fitting operator product expansion formulas to the lattice data. The quark propagators are computed on domain wall fermion configurations generated by the RBC-UKQCD Collaborations with N f = 2+1 flavors. Three ensembles with different light sea quark masses are used at one lattice spacing 1/a = 1.75(4) GeV. We obtain in the SU(2) chiral limit. Supported by National Natural Science Foundation of China (11575197, 11575196, 11335001, 11405178), joint funds of NSFC (U1632104, U1232109), YC and ZL acknowledge the support of NSFC and DFG (CRC110)
Diquark condensation and the quark-quark interaction
International Nuclear Information System (INIS)
Bloch, J. C. R.; Roberts, C. D.; Schmidt, S. M.
1999-01-01
We employ a bispinor gap equation to study superfluidity at nonzero chemical potential, μ≠0, in two- and three-color QCD, exploring the gap's sensitivity to the nature of the quark-quark interaction. The two-color theory, QC 2 D, is an excellent exemplar; the order of truncation of the quark-quark scattering kernel K has no qualitative impact, which allows a straightforward elucidation of the effects of μ when the coupling is strong. In the three-color theory the rainbow-ladder truncation admits diquark bound states, a defect that is eliminated by an improvement of K. The corrected gap equation describes a superfluid phase that is semiquantitatively similar to that obtained using the rainbow truncation. A model study suggests that the width of the superfluid gap and the transition point in QC 2 D provide reliable quantitative estimates of those quantities in QCD. (c) 1999 The American Physical Society
Quark-anti-quark potential in N=4 SYM
Energy Technology Data Exchange (ETDEWEB)
Gromov, Nikolay [Mathematics Department, King’s College London,The Strand, London WC2R 2LS (United Kingdom); St. Petersburg INP,Gatchina, 188 300, St.Petersburg (Russian Federation); Levkovich-Maslyuk, Fedor [Mathematics Department, King’s College London,The Strand, London WC2R 2LS (United Kingdom); Nordita, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, SE-106 91 Stockholm (Sweden)
2016-12-22
We construct a closed system of equations describing the quark-anti-quark potential at any coupling in planar N=4 supersymmetric Yang-Mills theory. It is based on the Quantum Spectral Curve method supplemented with a novel type of asymptotics. We present a high precision numerical solution reproducing the classical and one-loop string predictions very accurately. We also analytically compute the first 7 nontrivial orders of the weak coupling expansion. Moreover, we study analytically the generalized quark-anti-quark potential in the limit of large imaginary twist to all orders in perturbation theory. We demonstrate how the QSC reduces in this case to a one-dimensional Schrodinger equation. In the process we establish a link between the Q-functions and the solution of the Bethe-Salpeter equation.
Top quark studies at hadron colliders
Energy Technology Data Exchange (ETDEWEB)
Sinervo, P.K. [Univ. of Toronto, Ontario (Canada)
1997-01-01
The techniques used to study top quarks at hadron colliders are presented. The analyses that discovered the top quark are described, with emphasis on the techniques used to tag b quark jets in candidate events. The most recent measurements of top quark properties by the CDF and DO Collaborations are reviewed, including the top quark cross section, mass, branching fractions, and production properties. Future top quark studies at hadron colliders are discussed, and predictions for event yields and uncertainties in the measurements of top quark properties are presented.
Quark virtuality and QCD vacuum condensates
International Nuclear Information System (INIS)
Zhou Lijuan; Ma Weixing
2004-01-01
Based on the Dyson-Schwinger equations (DSEs) in the 'rainbow' approximation, the authors investigate the quark virtuality in the vacuum state and quantum-chromodynamics (QCD) vacuum condensates. In particular, authors calculate the local quark vacuum condensate and quark-gluon mixed condensates, and then the virtuality of quark. The calculated quark virtualities are λ u,d 2 =0.7 GeV 2 for u, d quarks, and λ s 2 =1.6 GeV 2 for s quark. The theoretical predictions are consistent with empirical values used in QCD sum rules, and also fit to lattice QCD predictions
Top quark studies at hadron colliders
International Nuclear Information System (INIS)
Sinervo, P.K.
1997-01-01
The techniques used to study top quarks at hadron colliders are presented. The analyses that discovered the top quark are described, with emphasis on the techniques used to tag b quark jets in candidate events. The most recent measurements of top quark properties by the CDF and DO Collaborations are reviewed, including the top quark cross section, mass, branching fractions, and production properties. Future top quark studies at hadron colliders are discussed, and predictions for event yields and uncertainties in the measurements of top quark properties are presented
Top quark studies at hadron colliders
International Nuclear Information System (INIS)
Sinervo, P.K.
1996-08-01
The techniques used to study top quarks at hadron colliders are presented. The analyses that discovered the top quark are described, with emphasis on the techniques used to tag b quark jets in candidate events. The most recent measurements of top quark properties by the CDF and D null collaborations are reviewed, including the top quark cross section, mass, branching fractions and production properties. Future top quark studies at hadron colliders are discussed, and predictions for event yields and uncertainties in the measurements of top quark properties are presented
SHORT COMMUNICATION CHEMICAL CONSTITUENTS AND ...
African Journals Online (AJOL)
CHEMICAL CONSTITUENTS AND ANTIOXIDANT ACTIVITIES OF THE FRUITS ... alkaloids, phenols, steroids, flavonoids, saponins and terpenoids while tannin ..... Harveer, K.; Jasmeen, S. Synthesis, characterization and radical scavenging ...
Theoretical estimation of Photons flow rate Production in quark gluon interaction at high energies
Al-Agealy, Hadi J. M.; Hamza Hussein, Hyder; Mustafa Hussein, Saba
2018-05-01
photons emitted from higher energetic collisions in quark-gluon system have been theoretical studied depending on color quantum theory. A simple model for photons emission at quark-gluon system have been investigated. In this model, we use a quantum consideration which enhances to describing the quark system. The photons current rate are estimation for two system at different fugacity coefficient. We discussion the behavior of photons rate and quark gluon system properties in different photons energies with Boltzmann model. The photons rate depending on anisotropic coefficient : strong constant, photons energy, color number, fugacity parameter, thermal energy and critical energy of system are also discussed.
Domain wall QCD with physical quark masses
Blum, T.; Christ, N.H.; Frison, J.; Garron, N.; Hudspith, R.J.; Izubuchi, T.; Janowski, T.; Jung, C.; Jüttner, A.; Kelly, C.; Kenway, R.D.; Lehner, C.; Marinkovic, M.; Mawhinney, R.D.; McGlynn, G.; Murphy, D.J.; Ohta, S.; Portelli, A.; Sachrajda, C.T.; Soni, A.
2016-01-01
We present results for several light hadronic quantities ($f_\\pi$, $f_K$, $B_K$, $m_{ud}$, $m_s$, $t_0^{1/2}$, $w_0$) obtained from simulations of 2+1 flavor domain wall lattice QCD with large physical volumes and nearly-physical pion masses at two lattice spacings. We perform a short, O(3)%, extrapolation in pion mass to the physical values by combining our new data in a simultaneous chiral/continuum `global fit' with a number of other ensembles with heavier pion masses. We use the physical values of $m_\\pi$, $m_K$ and $m_\\Omega$ to determine the two quark masses and the scale - all other quantities are outputs from our simulations. We obtain results with sub-percent statistical errors and negligible chiral and finite-volume systematics for these light hadronic quantities, including: $f_\\pi$ = 130.2(9) MeV; $f_K$ = 155.5(8) MeV; the average up/down quark mass and strange quark mass in the $\\bar {\\rm MS}$ scheme at 3 GeV, 2.997(49) and 81.64(1.17) MeV respectively; and the neutral kaon mixing parameter, $B_K$...
Effects of dynamical quarks in UKQCD simulations
International Nuclear Information System (INIS)
Allton, Chris
2002-01-01
Recent results from the UKQCD Collaboration's dynamical simulations are presented. The main feature of these ensembles is that they have a fixed lattice spacing and volume, but varying sea quark mass from infinite (corresponding to the quenched simulation) down to roughly that of the strange quark mass. The main aim of this work is to uncover dynamical quark effects from these 'matched' ensembles. We obtain some evidence of dynamical quark effects in the static quark potential with less effects in the hadronic spectrum
Heavy quarks and CP: Moriond 1985
International Nuclear Information System (INIS)
Bjorken, J.D.
1985-03-01
The presentations at the Fifth Moriond Workshop on Heavy Quarks, Flavor Mixing, and CP Violation (La Plagne, France, January 13-19, 1985) are summarized. The following topics are reviewed. What's New (beyond the top, top quarks, bottom quarks, charm quarks, strange quarks, and others); why is all this being done (strong interactions and hadron structure, and electroweak properties); and what next (facilities and can one see CP violation in the B-anti B system). 64 refs., 10 figs
Top Quark Mass Measurements at ATLAS and CMS
McCarthy, Tom; The ATLAS collaboration
2016-01-01
The top quark mass ($m_{top}$) is a fundamental parameter of the Standard Model of Particle Physics (SM). As the heaviest of all known SM particles with a mass close to the EW symmetry breaking scale, the top quark plays a pivotal role in the theory of elementary particles. The exact value of the top quark mass has implications on a number of theoretical predictions, which motivates the need for precision measurements of $m_{top}$. This presentation highlights a number of such precision measurements carried out by the ATLAS and CMS collaborations at centre-of-mass energies of $\\sqrt{s}=7$ and $8$ TeV from the combined LHC Run I datasets. A wide range of analysis strategies are employed in a number of channels. Measurements of both the top quark pole mass and $m_{top}$ as defined by the Monte Carlo generator in simulated signal samples are shown. Finally, a summary of combinations of the LHC measurements is presented, together with a look toward top quark mass measurements at $\\sqrt{s}=13$ TeV.
Quark effects in nuclear physics
International Nuclear Information System (INIS)
Scholten, O.
1990-01-01
The magnitude of the quark effect for low-energy nuclear physics is investigated. Coulomb energy is studied in the A=3 system in order to determine the effect of the composite structure of the nucleon. In the actual calculations a non-relativistic quark-cluster model description has been used. A nucleon size b=0.617 fm, the width of the relative wave function Φ of the quarks in the nucleon, has been assumed. It is concluded that the contribution to Coulomb energies due to quark effects are significant compared to the observed Nolen-Schiffer anomaly. However these do not provide the long searched for 'smoking gun'. When the free parameters that appear in the calculation are adjusted to reproduce the same charge form factor, the calculated anomalies are not significantly different. 2 figs., 2 tabs., 8 refs.2
Heavy quark and magnetic moment
International Nuclear Information System (INIS)
Mubarak, Ahmad; Jallu, M.S.
1979-01-01
The magnetic moments and transition moments of heavy hadrons including the conventional particles are obtained under the SU(5) truth symmetry scheme. To this end state vectors are defined and the quark additivity principle is taken into account. (author)
Quark potential of spontaneous strings
International Nuclear Information System (INIS)
German, G.; Kleinert, H.
1989-01-01
The authors present some recent developments in string models with an extrinsic curvature term in action. Particular emphasis is placed upon the static quark potential and on the thermal deconfinement properties of spontaneous strings
Dilip, Jana
2008-01-01
The ATLAS potential for the study of the top quark properties and physics beyond the Standard Model in the top quark sector, is described. The measurements of the top quark charge, the spin and spin correlations, the Standard Model decay (t-> bW), rare top quark decays associated to flavour changing neutral currents (t-> qX with X = gluon, Z, photon) and ttbar resonances are discussed. The sensitivity of the ATLAS experiment is estimated for an expected luminosity of 1fb-1 at the LHC. The full simulation of the ATLAS detector is used. For the Standard Model measurements the expected precision is presented. For the tests of physics beyond the Standard Model, the 5 sigma discovery potential (in the presence of a signal) and the 95% Confidence Level (CL) limit (in the absence of a signal) are given.
CERN. Geneva
2011-01-01
Higgs mechanism. There are various hints at deviations from the Standard Model expectation which have been observed recently by Tevatron experiments in top final states. Several signatures of new physics accessible at the LHC either suffer from top-quark production as a significant background or contain top quarks themselves. In this talk, we present results on top quark physics obtained from the first LHC data collected by the CMS experiment.They include measurements of the top pair production cross section in various channels and their combination, measurements of the top quark mass, the single top cross section, a search for new particles decaying into top pairs, and a first look at the charge asymmetry.
Dumé, Belle
2003-01-01
"Physicists working at the Relativistic Heavy Ion Collider (RHIC) at the Brookhaven National Laboratory in the US say that they have come closer than ever before to creating a quark-gluon plasma" (0.5 page)
Colour screening and quark confinement
International Nuclear Information System (INIS)
Mack, G.
1978-03-01
It is proposed that in Quantum Chromodynamics the colour charge of gluons and of anything with zero triality is screened by a dynamical Higgs mechanism with Higgs scalars made out of gluons. The center Z 3 of the gauge group SU(3) is left unbroken in this way, and single quarks, which have nonzero triality, cannot be screened. Long range forces between them persist therefore. Given that the Higgs mechanism produces a mass gap, the most favorable configuration of field lines between e.g. quark and antiquark will be in strings analogous to magnetic field lines in a superconductor. The strings confine the quarks. The screening mechanism, on the other hand, produces not only the mass gap (which leads to string formation) but is also responsible for saturation of forces, i.e. absence of bound states of six quarks etc. (orig.) [de
Colour screening and quark confinement
International Nuclear Information System (INIS)
Mack, G.
1978-01-01
It is proposed that in quantum chromodynamics the colour charge of gluons and of anything with zero triality is screened by a dynamic Higgs mechanism with Higgs scalars made out of gluons, but the center Z 3 of the gauge group SU(3) is left unbroken, and single quarks, which have nonzero triality, are not screened. Long range forces between them persist therefore. Given that the Higgs mechanism produces a mass gap, the most favourable configuration of field lines between e.g., quark and antiquark will be in strings analogous to magnetic field lines in a superconductor. The string confine the quarks. The screening mechanism, on the other hand, produces not only the mass gap (which leads to string formation) but is also responsible for saturation of forces, i.e. absence of bound states of six quarks, etc. (Auth.)
Generation labels in composite models for quarks and leptons
International Nuclear Information System (INIS)
Harari, H.; Seiberg, N.
1981-03-01
Models in which quarks and leptons are approximately massless composites of fundamental massless fermions which are confined by a hypercolor force are considered. The fundamental Lagrangian exhibits an axial U(1)sub(X) symmetry which is broken by hypercolor instantons, leaving a conserved discrete subgroup. It is proposed that the distinction between different generations of quarks and leptons is given by the X-number. The resulting generation labelling scheme does not lead to massless Goldstone bosons or to new anomalies and is based on a quantum number which is already contained in the theory. The dynamical rishon model is described as an illustrative example. (H.K.)
International Nuclear Information System (INIS)
Toki, H.
2000-01-01
We discuss the research fields to be studied by the Japan Hadron Facility being planned in the site of JAERI as a joint project with Neutron Science Project. We would expect to reveal the most microscopic structure of matter using the intensity frontier proton machine. In particular, we would like to develop Quark Nuclear Physics to describe hadrons and nuclei in terms of quarks and gluons. (author)
Heavy quark production and spectroscopy
International Nuclear Information System (INIS)
Appel, J.A.
1993-11-01
This review covers many new experimental results on heavy flavor production and spectroscopy. It also shows some of the increasingly improved theoretical understanding of results in light of basic perturbative QCD and heavy quark symmetry. At the same time, there are some remaining discrepancies among experiments as well as significant missing information on some of the anticipated lowest lying heavy quark states. Most interesting, perhaps, are some clearly measured production effects awaiting full explanation
Quark effects in nuclear structure
International Nuclear Information System (INIS)
Watt, A.
1987-01-01
Some experimental data in nuclear structure physics cannot be explained on the assumption that nuclei consist of inert protons and neutrons. The quark model attributes a definite internal structure to nucleons and implies that their properties should change when embedded in a nucleus. This article reviews some of the experimental evidence for these effects and discusses some new aspects of nuclear structure predicted by the quark model
Sextet quarks and light pseudoscalars
International Nuclear Information System (INIS)
Clark, T.E.; Leung, C.N.; Love, S.T.; Rosner, J.L.; Chicago Univ., IL
1986-01-01
Light pseudoscalar bosons are a very general consequence of the existence of higher-color representations (such as sextets) of quarks. It is shown that if the condensate vertical stroke vertical stroke=F 3 defines a scale F>>Λ QCD , as has been expected on the basis of perturbative and lattice calculations, then present limits on axions exclude a wide range of values of F. Such limits therefore serve as complements to direct accelerator searches for higher-color quarks. (orig.)
Theory of quark mixing matrix and invariant functions of mass matrices
International Nuclear Information System (INIS)
Jarlskog, C.
1987-10-01
The outline of this talk is as follows: The origin of the quark mixing matrix. Super elementary theory of flavour projection operators. Equivalences and invariances. The commutator formalism and CP violation. CP conditions for any number of families. The 'angle' between the quark mass matrices. Application to Fritzsch and Stech matrices. References. (author)
Semileptonic Decays of Heavy Lambda Baryons in a Quark Model
Energy Technology Data Exchange (ETDEWEB)
Winston Roberts; Muslema Pervin; Simon Capstick
2005-03-01
The semileptonic decays of {Lambda}{sub c} and {Lambda}{sub b} are treated in the framework of a constituent quark model. Both nonrelativistic and semirelativistic Hamiltonians are used to obtain the baryon wave functions from a fit to the spectra, and the wave functions are expanded in both the harmonic oscillator and Sturmian bases. The latter basis leads to form factors in which the kinematic dependence on q{sup 2} is in the form of multipoles, and the resulting form factors fall faster as a function of q{sup 2} in the available kinematic ranges. As a result, decay rates obtained in the two models using the Sturmian basis are significantly smaller than those obtained using the harmonic oscillator basis. In the case of the {Lambda}{sub c}, decay rates calculated using the Sturmian basis are closer to the experimentally reported rates. However, we find a semileptonic branching fraction for the {Lambda}{sub c} to decay to excited {Lambda}* states of 11% to 19%, in contradiction with what is assumed in available experimental analyses. Our prediction for the {Lambda}{sub b} semileptonic decays is that decays to the ground state {Lambda}{sub c} provide a little less than 70% of the total semileptonic decay rate. For the decays {Lambda}{sub b} {yields} {Lambda}{sub c}, the analytic form factors we obtain satisfy the relations expected from heavy-quark effective theory at the non-recoil point, at leading and next-to-leading orders in the heavy-quark expansion. In addition, some features of the heavy-quark limit are shown to naturally persist as the mass of the heavy quark in the daughter baryon is decreased.
Constituency Input into Budget Management.
Miller, Norman E.
1995-01-01
Presents techniques for ensuring constituency involvement in district- and site-level budget management. Outlines four models for securing constituent input and focuses on strategies to orchestrate the more complex model for staff and community participation. Two figures are included. (LMI)
Polarization in heavy quark decays
Energy Technology Data Exchange (ETDEWEB)
Alimujiang, K.
2006-07-01
In this thesis I concentrate on the angular correlations in top quark decays and their next.to.leading order (NLO) QCD corrections. I also discuss the leading.order (LO) angular correlations in unpolarized and polarized hyperon decays. In the first part of the thesis I calculate the angular correlation between the top quark spin and the momentum of decay products in the rest frame decay of a polarized top quark into a charged Higgs boson and a bottom quark in Two-Higgs-Doublet-Models: t({up_arrow}) {yields} b + H{sup +}. I provide closed form formulae for the O({alpha}{sub s}) radiative corrections to the unpolarized and the polar correlation functions for m{sub b}{ne}0 and m{sub b}=0. In the second part I concentrate on the semileptonic rest frame decay of a polarized top quark into a bottom quark and a lepton pair: t({up_arrow}){yields}X{sub b}+l{sup +}+{nu}{sub l}. I present closed form expressions for the O({alpha}{sub s}) radiative corrections to the unpolarized part and the polar and azimuthal correlations for m{sub b}{ne}0 and m{sub b}=0. In the last part I turn to the angular distribution in semileptonic hyperon decays. Using the helicity method I derive complete formulas for the leading order joint angular decay distributions occurring in semileptonic hyperon decays including lepton mass and polarization effects. (orig.)
Searching for color sextet quarks at high energy hardon colliders
International Nuclear Information System (INIS)
Kantar, M.
2005-01-01
We analyze the resonance and pair production of color sextet quarks and their decay modes at very high energy hadron colliders such as VHLC (Very Large Hadron Collider) with the energy of 28 TeV and SSC (Superconducting Super Collider) for two options with energies of 40 TeV and 100 TeV, respectively. The total cross sections of color sextet quark for three different machines are calculated and plotted versus its mass. The distributions of transverse momentum T p and invariant mass jj m of two final state jets are plotted for signals and backgrounds and analyzed the discovery limits of this resonance particle. The observation condition of color sextet quarks are performed by the number of signal events to the number of background events
International Nuclear Information System (INIS)
Barik, N.; Das, M.
1983-01-01
The effect of confinement on the magnetic moment of a quark has been studied in a simple independent-quark model based on the Dirac equation with a power-law potential. The magnetic moments so obtained for the constituent quarks, which are found to be significantly different from their corresponding Dirac moments, are used in predicting the magnetic moments of baryons in the nucleon octet as well as those in the charmed and b-flavored sectors. We not only get an improved result for the proton magnetic moment, but the calculation for the rest of the nucleon octet also turns out to be in reasonable agreement with experiment. The overall predictions for the charmed and b-flavored baryons are also comparable with other model predictions
Quark-diquark approximation of the three-quark structure of baryons in the quark confinement model
International Nuclear Information System (INIS)
Efimov, G.V.; Ivanov, M.A.; Lyubovitskij, V.E.
1990-01-01
Octet (1 + /2) and decuplet (3 + /2) of baryons as relativistic three-quark states are investigated in the quark confinement model (QCM), the relativistic quark model, based on some assumptions about hadronization and quark confinement. The quark-diquark approximation of the three-quark structure of baryons is proposed. In the framework of this approach the description of the main low-energy characteristics of baryons as magnetic moments, electromagnetic radii and form factors, ratio of axial and vector constants in semileptonic baryon octet decays, strong form factors and decay widths is given. The obtained results are in agreement with experimental data. 31 refs.; 4 figs.; 5 tabs
Composite quarks and their magnetic moments
International Nuclear Information System (INIS)
Parthasarathy, R.
1980-08-01
A composite quark model based on the symmetry group SU(10)sub(flavour) x SU(10)sub(colour) with the assumption of mass non-degenerate sub-quarks is considered. Magnetic moments of quarks and sub-quarks are obtained from the observed nucleon magnetic moments. Using these quark and sub-quark magnetic moments, a satisfactory agreement for the radiative decays of vector mesons (rho,ω) is obtained. The ratio of the masses of the sub-quarks constituting the u,d,s quarks are found to be Msub(p)/Msub(n) = 0.3953 and Msub(p)/Msub(lambda) = 0.596, indicating a mass hierarchy Msub(p) < Msub(n) < Msub(lambda) for the sub-quarks. (author)
Top quark production at the LHC
Gilles, Geoffrey; The ATLAS collaboration
2018-01-01
The top quark is the heaviest known fundamental particle. As it is the only quark that decays before it hadronizes, it gives us the unique opportunity to probe the properties of bare quarks at the Large Hadron Collider. This talk will present highlights of a few recent precision measurements of the top quark using 13 TeV and 8 TeV collision data: top-quark pair and single top production cross sections, including differential distributions and production in association with bosons, will be presented alongside top quark properties measurements. These measurements, including results using boosted top quarks, probe our understanding of top quark production in the TeV regime. Measurements of the top quark mass are also presented.
International Nuclear Information System (INIS)
Harari, H.
1977-01-01
The physics of quarks and leptons within the framework of gauge theories for the weak and electromagnetic interactions is reviewed. The Weinberg-Salam SU(2)xU(1) theory is used as a ''reference point'' but models based on larger gauge groups, especially SU(2)sub(L)xSU(2)sub(R)xU(1), are discussed. We distinguish among three ''Generations'' of fundamental fermions: The first generation (e - , νsub(e), u, d), the second generation (μ - , νsub(μ), c, s) and the third generation (tau - , νsub(tau), t, b). For each generation are discussed the classification of all fermions, the charged and neutral weak currents, possible right-handed currents, parity and CP-violation, fermion masses and Cabibbo-like angles and related problems. Theoretical ideas as well as experimental evidence, emphasizing open theoretical problems and possible experimental tests are reviewed, as well as the possibility of unifying the weak, electromagnetic and strong interactions in a grand unification scheme. The problems and their possible solutions are presented, generation by generation, but a brief subject-index (following the table of contents) enbales the interested reader to follow any specific topic throughout the three generations. (author)
AUTHOR|(SzGeCERN)655637
The measurement of prompt photon associated with a b jet in proton-proton interactions can provide us insight into the inner structure of proton. This is because precision of determination of parton distribution functions of b quark and gluon can be increased by such a measurement. The measurement of cross-section of prompt photon associated with a b jet (process $pp\\longrightarrow \\gamma + b + X$) at $\\sqrt{s}$= 8 TeV with the ATLAS detector is presented. Full 8 TeV dataset collected by ATLAS during the year 2012 was used in this analysis. Corresponding integrated luminosity is 20.3 $fb^{-1}$. Fiducial differential cross-section as a function of photon transverse momentum at particle level was extracted from data and compared with the prediction of leading order event generator Pythia 8. Cross-section extracted from data is normalised independently on the Monte Carlo prediction. Values of data distribution lie above Monte Carlo values. The difference can be explained by presence of higher order effects not ...
CP violation for electroweak baryogenesis from mixing of standard model and heavy vector quarks
International Nuclear Information System (INIS)
McDonald, J.
1996-01-01
It is known that the CP violation in the minimal standard model is insufficient to explain the observed baryon asymmetry of the Universe in the context electroweak baryogenesis. In this paper we consider the possibility that the additional CP violation required could originate in the mixing of the standard model quarks and heavy vector quark pairs. We consider the baryon asymmetry in the context of the spontaneous baryogenesis scenario. It is shown that, in general, the CP-violating phase entering the mass matrix of the standard model and heavy vector quarks must be space dependent in order to produce a baryon asymmetry, suggesting that the additional CP violation must be spontaneous in nature. This is true for the case of the simplest models which mix the standard model and heavy vector quarks. We derive a charge potential term for the model by diagonalizing the quark mass matrix in the presence of the electroweak bubble wall, which turns out to be quite different from the fermionic hypercharge potentials usually considered in spontaneous baryogenesis models, and obtain the rate of baryon number generation within the wall. We find, for the particular example where the standard model quarks mix with weak-isodoublet heavy vector quarks via the expectation value of a gauge singlet scalar, that we can account for the observed baryon asymmetry with conservative estimates for the uncertain parameters of electroweak baryogenesis, provided that the heavy vector quarks are not heavier than a few hundred GeV and that the coupling of the standard model quarks to the heavy vector quarks and gauge singlet scalars is not much smaller than order of 1, corresponding to a mixing angle of the heavy vector quarks and standard model quarks not much smaller than order of 10 -1 . copyright 1996 The American Physical Society
Valence QCD: Connecting QCD to the quark model
International Nuclear Information System (INIS)
Liu, K.F.; Dong, S.J.; Draper, T.; Sloan, J.; Leinweber, D.; Woloshyn, R.M.
1999-01-01
A valence QCD theory is developed to study the valence quark properties of hadrons. To keep only the valence degrees of freedom, the pair creation through the Z graphs is deleted in the connected insertions, whereas the sea quarks are eliminated in the disconnected insertions. This is achieved with a new 'valence QCD' Lagrangian where the action in the time direction is modified so that the particle and antiparticle decouple. It is shown in this valence version of QCD that the ratios of isovector to isoscalar matrix elements (e.g., F A /D A and F S /D S ratios) in the nucleon reproduce the SU(6) quark model predictions in a lattice QCD calculation. We also consider how the hadron masses are affected on the lattice and discover new insights into the origin of dynamical mass generation. It is found that, within statistical errors, the nucleon and the Δ become degenerate for the quark masses we have studied (ranging from 1 to 4 times the strange mass). The π and ρ become nearly degenerate in this range. It is shown that valence QCD has the C, P, T symmetries. The lattice version is reflection positive. It also has the vector and axial symmetries. The latter leads to a modified partially conserved axial Ward identity. As a result, the theory has a U(2N F ) symmetry in the particle-antiparticle space. Through lattice simulation, it appears that this is dynamically broken down to U q (N F )xU bar q (N F ). Furthermore, the lattice simulation reveals spin degeneracy in the hadron masses and various matrix elements. This leads to an approximate U q (2N F )xU bar q (2N F ) symmetry which is the basis for the valence quark model. In addition, we find that the masses of N, Δ,ρ,π,a 1 , and a 0 all drop precipitously compared to their counterparts in the quenched QCD calculation. This is interpreted as due to the disappearance of the 'constituent' quark mass which is dynamically generated through tadpole diagrams. The origin of the hyperfine splitting in the baryon is
Höing, Rebekka Sophie; Haller, Johannes
2015-01-01
A search for pairs of vector-like T' quark produced in proton-proton collisions recorded with the CMS experiment at p s = 8 TeV is presented. The search is optimized for decays of T' quarks to top quarks and Higgs bosons, where the top quarks and Higgs bosons decay hadronically. The T'-quark mass range between 500 and 1000 GeV is investigated. The top quarks and Higgs bosons produced in decays of the heavy T' quarks acquire large Lorentz boosts. The signatures of these particles in the detector can overlap and are therefore dicult to resolve using classical jet reconstruction methods. Large-radius jets are reconstructed and subjets formed from their constituents. The decay products of particles with large Lorentz boosts are highly collimated and can all be found within a single one of these large-radius jets. Top jets containing hadronic top-quark decays are identied with a top-tagging algorithm that analyzes the jet substructure. A b-tagging algorithm is applied to the reconstructed subjets in order to nd bo...
A new kind of bottom quark factory
International Nuclear Information System (INIS)
Mtingwa, S.K.; Strikman, M.; AN SSSR, Leningrad
1991-01-01
We describe a novel method of producing large numbers of B mesons containing bottom quarks. It is known that one should analyze at least 10 9 B meson decays to elucidate the physics of CP violation and rare B decay modes. Using the ultra high energy electron beams from the future generation of electron linear colliders, we Compton backscatter low energy laser beams off these electron beams. From this process, we produce hot photons having energy hundreds of GeV. Upon scattering these hot photons onto stationary targets, we show that it is possible to photoproduce and measure the necessary 10 9 B mesons per year. 24 refs., 4 figs
Quark color-hyperfine interactions in baryons
International Nuclear Information System (INIS)
Anselmino, M.; Lichtenberg, D.B.
1990-01-01
We consider the contribution from the color-hyperfine interaction to the energies of groundstate hadrons, with an emphasis on baryons. We use experimental information about how the color-hyperfine term depends on flavor to make predictions about the masses of baryons containing a heavy quark. We then generalize some relations between color-hyperfine matrix elements in mesons and baryons to obtain a number of additional predictions about the masses of as-yet unobserved baryons. Most of our predictions are in the form of inequalities. (orig.)
The Ways of Four-Quark Hadrons
CERN. Geneva
2014-01-01
Ten years after the discovery of the X(3872) we can assert that a number of exotic four-quark hadrons with hidden charm and beauty have been discovered, the most recent, Z(3900), found by BES in 2013, being among the top-striking ones. However, ten years have not been enough to dispel the controversy about their inner structure, with two body hadron molecules and compact multiquark states being the withstanding antipodal models. In this seminar I will review the status of the field, presenting both the experimental facts and the theoretical pictures attempting to interpret them.
Inclusive production of large-p/sub T/ protons and quark-quark elastic scattering
International Nuclear Information System (INIS)
Chen, C.K.
1978-01-01
A proton-formation process in combination with hard quark-quark scattering is capable of explaining the observed large-p/sub T/ single-proton inclusive production data. This model implies that the inclusive production of two large-p/sub T/ protons at opposite directions is dominated by large-angle elastic scattering of two up quarks, and becomes an ideal place to study elastic quark-quark scattering. This two-proton inclusive production process is also ideal for the study of the spin structure of quark-quark elastic scattering, so the assumptions of pure vector-type quark-quark interaction and of colored quarks can be checked empirically. The consistency of applying the quark-elastic-scattering idea to large-angle elastic proton-proton scattering and to the inclusive production of large-p/sub T/ protons is also demonstrated
Heavy quark energy loss in nuclear medium
International Nuclear Information System (INIS)
Zhang, Benr-Wei; Wang, Enke; Wang, Xin-Nian
2003-01-01
Multiple scattering, modified fragmentation functions and radiative energy loss of a heavy quark propagating in a nuclear medium are investigated in perturbative QCD. Because of the quark mass dependence of the gluon formation time, the medium size dependence of heavy quark energy loss is found to change from a linear to a quadratic form when the initial energy and momentum scale are increased relative to the quark mass. The radiative energy loss is also significantly suppressed relative to a light quark due to the suppression of collinear gluon emission by a heavy quark
Strange Quark Matter Status and Prospects
Sandweiss, J.
2004-01-01
The existence of quark states with more than three quarks is allowed in QCD. The stability of such quark matter states has been studied with lattice QCD and phenomenological bag models, but is not well constrained by theory. The addition of strange quarks to the system allows the quarks to be in lower energy states despite the additional mass penalty. There is additional stability from reduced Coulomb repulsion. SQM is expected to have a low Z/A. Stable or metastable massive multiquark states contain u, d, and s quarks.
Searches for new heavy quarks in ATLAS
Nikiforou, Nikiforos; The ATLAS collaboration
2018-01-01
A search for new heavy quarks focusing on recent vector-like quark searches with the ATLAS detector at the CERN Large Hadron Collider is presented. Two recent searches targeting the pair production of type vector-like quarks are described. The first search is sensitive to vector-like up-type quark (T ) decays to a t quark and either a Standard Model Higgs boson or a Z boson. The second search is primarily sensitive to T decays to W boson and a b quark. Additionally, the results can be interpreted for alternative VLQ decays.
Radiation damage to DNA constituents
International Nuclear Information System (INIS)
Bergene, R.
1977-01-01
The molecular changes of the DNA molecule, in various systems exposed to inoizing radiation, have been the subject of a great number of studies. In the present work electron spin resonance spectroscopy (ESR) has been applied to irradiated crystalline systems, in particular single crystals of DNA subunits and their derivatives. The main conclusions about the molecular damage are based on this technique in combination with molecular orbital calculations. It should be emphasized that the ESR technique is restricted to damage containing unpaired electrons. These unstable intermediates called free radicals seem, however, to be involved in all molecular models describing the action of radiation on DNA. One of the premises for a detailed theory of the radiation induced reactions at the physico-chemical level seems to involve exact knowledge of the induced free radicals as well as the modes of their formation and fate. For DNA, as such, it is hardly possible to arrive at such a level of knowledge since the molecular complexity prevents selective studies of the many different radiation induced products. One possible approach is to study the free radicals formed in the constituents of DNA. In the present work three lines of approach should be mentioned. The first is based on the observation that radical formation in general causes only minor structural alterations to the molecule in question. The use of isotopes with different spin and magnetic moment (in particular deuterium) may also serve a source of information. Deuteration leads to a number of protons, mainly NH - and OH, becoming substituted, and if any of these are involved in interactions with unpaired protons the resonance pattern is influeneed. The third source of information is molecular orbital calculation. The electron spin density distribution is a function in the three dimensional space based on the system's electronic wave functions. This constitutes the basis for the idea that ESR data can be correlated with
Flavor Physics in the Quark Sector
Energy Technology Data Exchange (ETDEWEB)
Antonelli, Mario; /Frascati; Asner, David Mark; /Carleton U.; Bauer, Daniel Adams; /Imperial Coll., London; Becher, Thomas G.; /Fermilab; Beneke, M.; /Aachen, Tech. Hochsch.; Bevan, Adrian John; /Queen Mary, U. of London; Blanke, Monika; /Munich, Tech. U. /Munich, Max Planck Inst.; Bloise, C.; /Frascati; Bona, Marcella; /CERN; Bondar, Alexander E.; /Novosibirsk, IYF; Bozzi, Concezio; /INFN, Ferrara; Brod, Joachim; /Karlsruhe U.; Buras, Andrzej J.; /Munich, Tech. U.; Cabibbo, N.; /INFN, Rome /Rome U.; Carbone, A.; /INFN, Bologna; Cavoto, Gianluca; /INFN, Rome; Cirigliano, Vincenzo; /Los Alamos; Ciuchini, Marco; /INFN, Rome; Coleman, Jonathon P.; /SLAC; Cronin-Hennessy, Daniel P.; /Minnesota U.; Dalseno, J.P.; /KEK, Tsukuba /Glasgow U. /Queen Mary, U. of London /Freiburg U. /Charles U. /Pisa U. /Vienna, OAW /Imperial Coll., London /Bergen U. /INFN, Rome /Rome U. /Munich, Tech. U. /INFN, Rome /Rome U. /Southampton U. /INFN, Rome /Nara Women' s U. /Florida U. /INFN, Turin /Turin U. /Edinburgh U. /Warwick U. /INFN, Rome /Rome U. /Massachusetts U., Amherst /KEK, Tsukuba /Bern U. /CERN /Munich, Tech. U. /Mainz U., Inst. Phys. /Wayne State U. /Munich, Max Planck Inst. /CERN /Frascati /Brookhaven /Mainz U., Inst. Kernphys. /Munich, Tech. U. /Siegen U. /Imperial Coll., London /Victoria U. /KEK, Tsukuba /Fermilab /Washington U., St. Louis /Frascati /Warwick U. /Indian Inst. Tech., Madras /Melbourne U. /Princeton U. /Beijing, Inst. High Energy Phys. /INFN, Rome /INFN, Rome3 /Fermilab /SLAC /York U., Canada /Brookhaven /UC, Irvine /INFN, Rome /Rome U. /Valencia U., IFIC /INFN, Padua /Padua U. /Munich, Max Planck Inst. /Barcelona U. /Warwick U. /Tata Inst. /Frascati /Mainz U., Inst. Phys. /Vienna U. /KEK, Tsukuba /Orsay, LPT /Frascati /Munich, Tech. U. /Brookhaven /Bern U. /CERN /Mainz U., Inst. Phys. /Wayne State U. /Valencia U., IFIC /CERN /Kentucky U. /Oxford U. /Iowa State U. /Bristol U. /INFN, Rome /Rutherford /CERN /Orsay, LAL /Glasgow U. /INFN, Padua /Queen Mary, U. of London /Texas U. /LPHE, Lausanne /Fermilab /UC, Santa Cruz /Vienna, OAW /Cincinnati U. /Frascati /Orsay, LAL /Ohio State U. /Purdue U. /Novosibirsk, IYF /Frascati /INFN, Rome /Padua U. /INFN, Rome /Bern U. /Karlsruhe U. /Brookhaven /CERN /Paris U., VI-VII /Zurich, ETH /Pisa U. /Frascati /Oxford U. /Orsay, LAL /INFN, Rome2 /INFN, Rome /INFN, Rome3 /Princeton U. /Fermilab /Queen' s U., Kingston /KEK, Tsukuba /Melbourne U. /Brookhaven /Indiana U. /INFN, Rome /Rome U. /Pisa U. /Mainz U., Inst. Phys. /Karlsruhe U. /Oxford U. /Cambridge U., DAMTP /Edinburgh U. /CERN
2010-08-26
In the past decade, one of the major challenges of particle physics has been to gain an in-depth understanding of the role of quark flavor. In this time frame, measurements and the theoretical interpretation of their results have advanced tremendously. A much broader understanding of flavor particles has been achieved, apart from their masses and quantum numbers, there now exist detailed measurements of the characteristics of their interactions allowing stringent tests of Standard Model predictions. Among the most interesting phenomena of flavor physics is the violation of the CP symmetry that has been subtle and difficult to explore. In the past, observations of CP violation were confined to neutral K mesons, but since the early 1990s, a large number of CP-violating processes have been studied in detail in neutral B mesons. In parallel, measurements of the couplings of the heavy quarks and the dynamics for their decays in large samples of K,D, and B mesons have been greatly improved in accuracy and the results are being used as probes in the search for deviations from the Standard Model. In the near future, there will be a transition from the current to a new generation of experiments, thus a review of the status of quark flavor physics is timely. This report is the result of the work of the physicists attending the 5th CKM workshop, hosted by the University of Rome 'La Sapienza', September 9-13, 2008. It summarizes the results of the current generation of experiments that is about to be completed and it confronts these results with the theoretical understanding of the field which has greatly improved in the past decade.
Spin effects in high energy quark-quark scattering
International Nuclear Information System (INIS)
Goloskokov, S.V.; Selyugin, O.V.
1993-01-01
The spin amplitudes in high-energy quark-quark scattering at /t/>1 GeV 2 are analyzed. It is shown that the gluon contributions in the QCDα s 3 order lead to the spin-flip amplitude growing as s. This means the existence of the spin-flip part in pomeron exchange. The resulting T f is about few per cent of the spin-non-flip contribution. The factorization of the large-distance and high-energy effects in the spin-flip amplitude is obtained. 13 refs.; 2 figs.; 1 tab
Constituency Orientation in Irish Politics
DEFF Research Database (Denmark)
Kusche, Isabel
2017-01-01
The constituency orientation of Irish politicians is a recurring topic in Irish political science. Its analysis has predominantly focused on TDs. This article uses a content analysis of candidate video statements in the general election 2016 in order to assess the strength of constituency...... this pattern, indicated by the weak constituency orientation in Dublin and Cork constituencies. Results also indicate differences between parties and some political statuses, while the gender of the candidates is of no relevance. Although the material does not permit a clear distinction between effects...... of political culture and short-term considerations, taken together the results indicate that localism in Irish politics matters, but in more complicated ways than usually depicted....
On exact account of heavy quark thresholds in hard processes
International Nuclear Information System (INIS)
Dokshitzer, Yu. L.
1993-01-01
We study the problem to accurately account for the heavy quark threshold effects in hard processes. We employ the direction perturbative Feynman diagram analysis and the Stueckelberg-Bogoliubov massive renormalization group formalism to show that both methods results in the same prescription for the 'physical' mass-dependent QCD effective coupling as an argument of anomalous dimensions that determine the evolution of structure function (parton distributions). By considering the one-loop example, we demonstrate that an intrinsic ambiguity of the standard approach based on the notion of 'effective number of quark flavours' may affect the α s determination at the level of two-loop effects
Analytical Formulae linking Quark Confinement and Chiral Symmetry Breaking
International Nuclear Information System (INIS)
Doi, Takahiro M.; Redlich, Krzysztof; Sasaki, Chihiro; Suganuma, Hideo
2016-01-01
Dirac spectrum representations of the Polyakov loop fluctuations are derived on the temporally odd-number lattice, where the temporal length is odd with the periodic boundary condition. We investigate the Polyakov loop fluctuations based on these analytical relations. It is semi-analytically and numerically found that the low-lying Dirac eigenmodes have little contribution to the Polyakov loop fluctuations, which are sensitive probe for the quark deconfinement. Our results suggest no direct one-to-one corresponding between quark confinement and chiral symmetry breaking in QCD
Covariant introduction of quark spin into the dual resonance model
International Nuclear Information System (INIS)
Iroshnikov, G.S.
1979-01-01
A very simple method of insertion of a quark spin into the dual resonance model of hadron interaction is proposed. The method is suitable for amplitudes with an arbitrary number of particles. The amplitude of interaction of real particles is presented as a product of contribution of oscillatory excitations in the (q anti q) system and of a spin factor. The latter is equal to the trace of the product of the external particle wave functions constructed from structural quarks and satisfying the relativistic Bargman-Wigner equations. Two examples of calculating the meson interaction amplitudes are presented
Dibaryon states containing two different types of heavy quarks
International Nuclear Information System (INIS)
Leandri, J.; Silvestre-Brac, B.
1995-01-01
In a recent series of papers we have shown that including heavy quarks in the dibaryon sector can lead to configurations stable against decay into two baryons. In this study we extend our previous work by a study of all the physical Q 2 q 4 [Q denotes a heavy quark and q denotes a member of the SU(3) F triplet representation] systems in a solvable chromomagnetic model. We propose a number of new heavy states which could be stable under strong interactions
Fundamental quark, lepton correspondence and dynamics with weak decay interactions
International Nuclear Information System (INIS)
Van der Spuy, E.
1977-10-01
A nonlinear fermion-field equation of motion and its (in principle) exact solutions, making use of the previously developed technique of infinite component free spinor fields, are discussed. It is shown to be essential for the existence of the solutions to introduce the isosymmetry breaking mechanism by coupling the isospin polarization of the domain of the universe of such particle fields to the field isospin. The essential trigger for the isosymmetry breaking mechanism is the existence of the electromagnetic interaction and the photon fields, carrying an infinite range isospin polarization change in the domain. A quartet of proton, neutron, lambda and charmed quark field solutions, with their respective characteristic Regge trajectories and primary isospin quantum numbers, and a quartet of lepton fields electron neutrino, electron, muon, muon nutrino, are shown to emerge naturally. The equations of motion of the quark and lepton propagators are deduced. The complicated charge nature of the quarks and the need for quark confinement is discussed and a correspondence principle is established between the quark and lepton field solutions. The correspondence is such that the dynamics of the leptons on their own appears to be compatible with quantum electrodynamics on the one hand, and on the other hand permits a natural GIM-Cabibbo weak decay interaction with a Cibibbo angle equal to the domain isospin polarization-change phase angle
The p-antip annihilation in the quark model
International Nuclear Information System (INIS)
Niskanen, J.A.
1988-05-01
After a concise review of the N-antiN annihilation in the quark rearrangement and 3 P 0 annihilation models, preliminary results are given for the case with an additional term where a q-antiq pair with the gluon quantum number 3 S 1
Some spectroscopic problems in the bag theory of quark confinement
International Nuclear Information System (INIS)
Jaffe, R.L.
1976-04-01
In addition to conventional mesons and baryons, the bag model predicts the existence of several classes of unusual hadrons. The spectroscopy of two classes of unconventional hadrons is discussed: first are the Q 2 antiQ 2 mesons; second are Q 3 baryons or QantiQ mesons with quantum numbers forbidden by the nonrelativistic quark model
Sub-color and leptoquark-quark symmetry
International Nuclear Information System (INIS)
Nakamura, Fumihiko
1982-01-01
On the basis of leptoquark-quark symmetry, we propose possible models, in which leptons and gauge bosons are constructed is SU(2) symmetry. In one of the cases, the subcolor is introduced as the quantum number of the leptoquark. Then the possibility of baryon decay is discussed. (author)
Heavy baryon transitions and the heavy quark effective theory
International Nuclear Information System (INIS)
Hussain, F.
1992-01-01
Heavy baryon decays are studied in the context of the Bethe-Salpeter approach to the heavy quark effective theory. A drastic reduction, in the number of independent form factors, is found. Results are presented both for heavy to heavy and heavy to light baryon decays. (orig.)
Dynamical quark and gluon condensates from a modified perturbative QCD
International Nuclear Information System (INIS)
Cabo Montes de Oca, A.; Martinez Pedrera, D.
2004-12-01
As it was suggested by previous works on a modified perturbation expansion for QCD, the possibility for the generation of large quark condensates in the massless version of the theory is explored. For this purpose, it is firstly presented a way to well define the Feynman diagrams at any number of loops by just employing dimensional regularization. After that, the calculated zero and one loop corrections to the effective potential indicate a strong instability of the system under the generation of quark condensates even in the absence of the gluon one. The quark condensate dependence of particular two loop terms does not modify the instability picture arising at one loop. The results suggest a possible mechanism for a sort of Top Condensate Model to be a dynamically fixed effective action for massless QCD. The inability of lattice calculations in detecting this possibility could be related to the current limitations in treating the fermion determinants. (author)
On the ultimate uncertainty of the top quark pole mass
Beneke, M.; Marquard, P.; Nason, P.; Steinhauser, M.
2017-12-01
We combine the known asymptotic behaviour of the QCD perturbation series expansion, which relates the pole mass of a heavy quark to the MS ‾ mass, with the exact series coefficients up to the four-loop order to determine the ultimate uncertainty of the top-quark pole mass due to the renormalon divergence. We perform extensive tests of our procedure by varying the number of colours and flavours, as well as the scale of the strong coupling and the MS ‾ mass. Including an estimate of the internal bottom and charm quark mass effect, we conclude that this uncertainty is around 110 MeV. We further estimate the additional contribution to the mass relation from the five-loop correction and beyond to be around 300 MeV.
Quark distributions in nuclear matter and the EMC effect
Energy Technology Data Exchange (ETDEWEB)
Mineo, H.; Bentz, W. E-mail: bentz@keyaki.cc.u-tokai.ac.jp; Ishii, N.; Thomas, A.W.; Yazaki, K
2004-05-03
Quark light cone momentum distributions in nuclear matter and the structure function of a bound nucleon are investigated in the framework of the Nambu-Jona-Lasinio model. This framework describes the nucleon as a relativistic quark-diquark state, and the nuclear matter equation of state by using the mean field approximation. The scalar and vector mean fields in the nuclear medium couple to the quarks in the nucleon and their effect on the spin independent nuclear structure function is investigated in detail. Special emphasis is placed on the important effect of the vector mean field and on a formulation which guarantees the validity of the number and momentum sum rules from the outset.
Pomeron-Quark Coupling from Charge Conjugation Invariance
International Nuclear Information System (INIS)
Zhou Lijuan; Wu Qing; Ma Weixing; Gu Yunting
2006-01-01
Based on the charge conjugation invariance and the vacuum property of the Pomeron, we point out that the commonly used vector vertex of the Pomeron coupling to quark is incorrect since it contradicts with the Pomeron property. We also claim that the soft Pomeron could be a tensor glueball ξ(2230) with quantum numbers I G J PC = 0 + 2 ++ and total decay width Γ tot ≅100 MeV, which lies on the soft Pomeron trajectory α p = 1.08+0.20t. Therefore, the coupling vertex of the soft Pomeron to quark should be tensorial which is invariant under the charge conjugation and can explain why the inadequate vector coupling, γ μ , of the soft Pomeron to quark is successful in dealing with Pomeron physics.
Quark exchange and nuclear dynamics
International Nuclear Information System (INIS)
Moniz, E.J.
1985-01-01
This paper gives a qualitative understanding of hadronic phenomena in terms of quark degrees of freedom. The basic model which incorporates saturating confining interactions and the study of hadron-hadron scattering has been carried through in collaboration with F. Lenz, J.T. Londergan, R. Rosenfelder, M. Stingl and K. Yazaki. It is shown that minimal confining dynamics together with exchange symmetry indeed leads to a remarkable range of phenomena at both the nuclear and particle energy scales. Most observables are well described by an effective hadron theory, the quark momentum distribution being the major exception. These features emerge even in the simplest model, namely, U(1) color and hadrons composed of two quarks (anti qq or qq). The author concentrates here on this model. In the concluding section, he remarks on the SU(N) results, particularly on the extent to which the color-hidden dynamics are constrained by examining the systematics of nuclear and hadronic phenomena. (Auth.)
Measuring the sea quark polarization
International Nuclear Information System (INIS)
Makdisi, Y.
1993-01-01
Spin is a fundamental degree of freedom and measuring the spin structure functions of the nucleon should be a basic endeavor for hadron physics. Polarization experiments have been the domain of fixed target experiments. Over the years large transverse asymmetries have been observed where the prevailing QCD theories predicted little or no asymmetries, and conversely the latest deep inelastic scattering experiments of polarized leptons from polarized targets point to the possibility that little of the nucleon spin is carried by the valence quarks. The possibility of colliding high luminosity polarized proton beams in the Brookhaven Relativistic Heavy Ion Collider (RHIC) provides a great opportunity to extend these studies and systematically probe the spin dependent parton distributions specially to those reactions that are inaccessible to current experiments. This presentation focuses on the measurement of sea quark and possibly the strange quark polarization utilizing the approved RHIC detectors
Waves in magnetized quark matter
Fogaça, D. A.; Sanches, S. M.; Navarra, F. S.
2018-05-01
We study wave propagation in a non-relativistic cold quark-gluon plasma immersed in a constant magnetic field. Starting from the Euler equation we derive linear wave equations and investigate their stability and causality. We use a generic form for the equation of state, the EOS derived from the MIT bag model and also a variant of the this model which includes gluon degrees of freedom. The results of this analysis may be relevant for perturbations propagating through the quark matter phase in the core of compact stars and also for perturbations propagating in the low temperature quark-gluon plasma formed in low energy heavy ion collisions, to be carried out at FAIR and NICA.
Heavy quark spectroscopy and decay
International Nuclear Information System (INIS)
Schindler, R.H.
1987-01-01
The understanding of q anti q systems containing heavy, charmed, and bottom quarks has progressed rapidly in recent years, through steady improvements in experimental techniques for production and detection of their decays. These lectures are meant to be an experimentalist's review of the subject. In the first of two lectures, the existing data on the spectroscopy of the bound c anti c and b anti b systems will be discussed. Emphasis is placed on comparisons with the theoretical models. The second lecture covers the rapidly changing subject of the decays of heavy mesons (c anti q and b anti q), and their excited states. In combination, the spectroscopy and decays of heavy quarks are shown to provide interesting insights into both the strong and electroweak interactions of the heavy quarks. 103 refs., 39 figs
Quark matter brings heavy ions to Oakland
International Nuclear Information System (INIS)
Klein, Spencer; Nystrand, Joakim
2004-01-01
The Quark Matter 2004 conference, held in Oakland, California, in January, provided participants with evidence for the elusive quark-gluon plasma. Spencer Klein and Joakim Nystrand describe the highlights of the meeting
On the Coulomb gauge quark propagator
International Nuclear Information System (INIS)
Kloker, M.; Alkofer, R.; Krassnigg, A.; Krenn, R.
2006-01-01
Full text: A solution of the quark Dyson-Schwinger equation including transverse gluons is presented. The corresponding retardation effects in the quark propagator are discussed. Especially, their effects on confinement properties and dynamical mass generation are described. (author)
International Nuclear Information System (INIS)
Rho, M.
1981-01-01
Quantum chromodynamics is believed to be candidate theory for the strong interactions and contains as its ingredients spinor quark fields and vector gluons, none of which can perhaps be ever liberated and detected in laboratories. A nucleus consists of nucleons bound by nuclear force which are however separately observable and which seem to preserve their identities even under extreme conditions. An intriguing question is: when compressed to high densities or heated to high temperature, at what point does a nuclear matter cease to be describable in terms of nucleon and meson degrees of freedom, but become a plasma of quarks and gluons; and how does this transition occur. This is not an idle question. If quarks and gluons are never to be observed isolated, then it may be that at low energies (or at low densities) they are not the right variables to do physics with. Instead hadrons must be. On the other hand, asymptotic freedom - the unique property of non-abelian gauge theories to which QCD belongs that quark-gluon and gluon-gluon interactions get weaker at short distances - tells us that at some large matter density the matter must necessarily be in the form of quark gas interacting only weakly. This means that a change in degrees of freedom must take place. We would like to know where this occurs and how. In this talk, I would like to address to this question by discussing first the large success we have had in understanding the role that mesons play in finite nuclei and nuclear matter and then attempting to correlate nucleon and meson degrees of freedom to quark-gluon degrees of freedom. In my opinion we are now at a stage where we feel fairly confident in our understanding of nucleon-meson structure of nuclei and nuclear matter and any further progress in deeper understanding of nuclear dynamics - and strong interactions - must come from QCD or its effective version, bags or strings. (orig.)
Quark degrees of freedom in compact stars
Energy Technology Data Exchange (ETDEWEB)
Marranghello, G.F.; Vasconcellos, C.A.Z. [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Inst. de Fisica. Dept. de Fisica; Hadjimichef, D. [Pelotas Univ., RS (Brazil). Inst. de Fisica e Matematica. Dept. de Fisica
2001-07-01
Nuclear matter may show a phase transition at high densities, where quarks and gluons are set free, forming a so called quark-gluon plasma. At the same range of densities, neutron stars are formed. In this work we have grouped both ideas in the study of the quark-gluon plasma formation inside compact stars, here treated as pure neutron star, hybrid star and pure quark matter star. (author)
Quark degrees of freedom in compact stars
International Nuclear Information System (INIS)
Marranghello, G.F.; Vasconcellos, C.A.Z.; Hadjimichef, D.
2001-01-01
Nuclear matter may show a phase transition at high densities, where quarks and gluons are set free, forming a so called quark-gluon plasma. At the same range of densities, neutron stars are formed. In this work we have grouped both ideas in the study of the quark-gluon plasma formation inside compact stars, here treated as pure neutron star, hybrid star and pure quark matter star. (author)
The weak conversion rate in quark matter
International Nuclear Information System (INIS)
Heiselberg, H.
1992-01-01
The weak conversion rate of strange to down quarks, s + u ↔ u + d, is calculated analytically for degenerate u, d and s quark matter to leading orders in temperature and deviations from chemical equilibrium. The rate is applied to burning of neutron matter into quark matter, to evaporation from quark nuggets in the early universe, for estimating the lifetime of strangelets, and to pulsar glitches
Top quark production at the Tevatron
Energy Technology Data Exchange (ETDEWEB)
Varnes, Erich W.; /Arizona U.
2010-09-01
The Fermilab Tevatron has, until recently, been the only accelerator with sufficient energy to produce top quarks. The CDF and D0 experiments have collected large samples of top quarks. We report on recent top quark production measurements of the single top and t{bar t} production cross sections, as well as studies of the t{bar t} invariant mass distribution and a search for highly boosted top quarks.
Free-quark phases in dense stars
Energy Technology Data Exchange (ETDEWEB)
Keister, B D; Kisslinger, L S [Carnegie-Mellon Univ., Pittsburgh, Pa. (USA). Dept. of Physics
1976-08-30
The possibility is examined that superdense matter can undergo a transition to a phase of free quarks within models which assume that the quark confinement potential is screened at high densities. The results imply that a phase of pure quarks of this type is unlikely to be found in stable stellar systems although they do not preclude the possible existence of a transition region which contains quarks and neutrons in equilibrium at the center of neutron stars.
Triplicity of hadrons, quarks and subquarks
International Nuclear Information System (INIS)
Terazawa, Hidezumi.
1989-11-01
Triplicity of hadrons, quarks and subquarks asserting that a certain physical quantity such as the weak current is taken equally well as either one of a composite operator of hadrons, that of quarks and that of subquarks is proposed. Among other things, the weak mixing angle, the quark mixing matrix and the mass sum rules for quarks and leptons are revisited, reinterpreted and discussed in detail in triplicity. (author)
An alternative approach to heavy quark bags
International Nuclear Information System (INIS)
Baacke, J.; Kasperidus, G.
1980-01-01
We discuss a formulation of quark bags where the quark wave function depends only on the relative coordinate and the bag boundary is fixed with respect to the center of mass of the quark system. For technical reasons we have to restrict ourselves to a heavy quark-antiquark system in an s-wave with spherical boundary. A phenomenological application to quarkonium states encourages further investigation of the approach. (orig.)
Pion electromagnetic polarizabilities and quarks
International Nuclear Information System (INIS)
Llanta, E.; Tarrach, R.
1980-01-01
The electric and magnetic polarizabilities of the neutral and charged pion are calculated in a coloured quark field theory at the one-loop level. The theory has as free parameter the quark mass but our results do not depend on it. We have found that the electric polarizabilities are αsub(π+-) = -0.04 α/m 3 sub(π), αsub(π 0 ) = -0.4 α/m 3 sub(π). These values are compared with calculations in other models and some comments are made about the polarizability sum rules. (orig.)
International Nuclear Information System (INIS)
Rho, M.
1983-11-01
The issue as to whether or not quarks will manifest themselves explicitly in nuclear processes is discussed in the light of the recently discovered topological structure of the baryon. Due to the leakage of the baryon charge from a confinement region (bag) into a meson-cloud region, there emerges a sort of topological equivalence principle which renders physically equivalent the description in terms of Goldstone meson fields alone (the Skyrmion) and the description in terms of a bag (confining quarks) surrounded by a meson cloud (the chiral bag model). How this new structure will modify our understanding of the nucleon and the nucleus is examined
The unconfined quarks and gluons
International Nuclear Information System (INIS)
Abdus Salam
1977-01-01
The consequences of the lepton-hadron gauge unification hypothesis with unconfined quarks and gluons being the hall-mark are discussed. Quark and gluon decays into leptons are shown to provide a new source of multileptonic production in NN, νN and μN collisions. A theorem is stated and proved which highlights the differences between the dynamics of gauge versus non-gauge 1 - particles. Empirical manifestations of gauge coloured mesons are discussed. The question of exact confinement or not is concluded to be in the end an empirical one and must be settled in the laboratory
Flavor Physics in the Quark Sector
Antonelli, Mario; Bauer, Daniel Adams; Becher, Thomas G.; Beneke, M.; Bevan, Adrian John; Blanke, Monika; Bloise, C.; Bona, Marcella; Bondar, Alexander E.; Bozzi, Concezio; Brod, Joachim; Buras, Andrzej J.; Cabibbo, N.; Carbone, A.; Cavoto, Gianluca; Cirigliano, Vincenzo; Ciuchini, Marco; Coleman, Jonathon P.; Cronin-Hennessy, Daniel P.; Dalseno, J.P.; Davies, C.H.; Di Lodovico, Francesca; Dingfelder, Jochen C.; Dolezal, Zdenek; Donati, Simone; Dungel, W.; Egede, Ulrik; Eigen, Gerald; Faccini, Riccardo; Feldmann, Thorsten; Ferroni, Fernando; Flynn, Jonathan M.; Franco, Enrico; Fujikawa, M.; Furic, Ivan K.; Gambino, Paolo; Gardi, E.; Gershon, Timothy John; Giagu, Stefano; Golowich, Eugene; Goto, Toru; Greub, C.; Grojean, Christophe; Guadagnoli, Diego; Haisch, U.A.; Harr, Robert Francis; Hoang, Andre H.; Hurth, Tobias; Isidori, Gino; Jaffe, D.E.; Juttner, Andreas; Jager, Sebastian; Khodjamirian, Alexander; Koppenburg, Patrick Stefan; Kowalewski, Robert V.; Krokovny, P.; Kronfeld, Andreas Samuel; Laiho, J.; Lanfranchi, G.; Latham, Thomas Edward; Libby, James F.; Limosani, A.; Lopes Pegna, David; Lu, Cai-Dian; Lubicz, Vittorio; Lunghi, Enrico; Luth, Vera G.; Maltman, K.; Marciano, William Joseph; Martin, Emilie Claire Mutsumi; Martinelli, Guido; Martinez-Vidal, Fernando; Masiero, A.; Mateu, V.; Mescia, Federico; Mohanty, Gagan Bihari; Moulson, Matthew; Neubert, Matthias; Neufeld, Helmut; Nishida, Shohei; Offen, Nils; Palutan, M.; Paradisi, Paride; Parsa, Z.; Passemar, Emilie; Patel, M.; Pecjak, B.D.; Petrov, Alexey A.; Pich, Antonio; Pierini, Maurizio; Plaster, Brad; Powell, Brian Alfred; Prell, Soeren Andre; Rademaker, J.; Rescigno, Marco; Ricciardi, Stefania; Robbe, Patrick; Rodrigues, E.; Rotondo, Marcello; Sacco, Roberto; Schilling, Christopher James; Schneider, Olivier; Scholz, Enno E.; Schumm, Bruce Andrew; Schwanda, C.; Schwartz, Alan Jay; Sciascia, Barbara; Serrano, Justine; Shigemitsu, J.; Shipsey, Ian P.J.; Sibidanov, A.L.; Silvestrini, Luca; Simonetto, Franco; Simula, Silvano; Smith, Christopher; Soni, A.; Sonnenschein, Lars; Sordini, Viola; Sozzi, Marco S.; Spadaro, Tommaso; Spradlin, Patrick Michael; Stocchi, Achille; Tantalo, Nazario; Tarantino, Cecilia; Telnov, Alexandre V.; Tonelli, Diego; Towner, I.S.; Trabelsi, K.; Urquijo, Phillip; Van de Water, R.S.; Van Kooten, Richard J.; Virto, Javier; Volpi, Guido; Wanke, R.; Westhoff, Susanne; Wilkinson, G.; Wingate, Matthew Bowen; Xie, Y.; Zupan, Jure
2010-01-01
One of the major challenges of particle physics has been to gain an in-depth understanding of the role of quark flavor and measurements and theoretical interpretations of their results have advanced tremendously: apart from masses and quantum numbers of flavor particles, there now exist detailed measurements of the characteristics of their interactions allowing stringent tests of Standard Model predictions. Among the most interesting phenomena of flavor physics is the violation of the CP symmetry that has been subtle and difficult to explore. Till early 1990s observations of CP violation were confined to neutral $K$ mesons, but since then a large number of CP-violating processes have been studied in detail in neutral $B$ mesons. In parallel, measurements of the couplings of the heavy quarks and the dynamics for their decays in large samples of $K, D$, and $B$ mesons have been greatly improved in accuracy and the results are being used as probes in the search for deviations from the Standard Model. In the near...
Heavy quark physics in ep collisions at LEP+LHC
International Nuclear Information System (INIS)
Ali, A.; Barreiro, F.; Troconiz, J.F. de; Schuler, G.A.; Bij, J.J. van der
1990-12-01
We study electroweak production of heavy quarks - charm, beauty, and top - in deep inelastic electron-proton collisions at the proposed LEP+LHC collider at CERN. The assumed energy for the collisions is E e =50 GeV, E p =8000 GeV, providing an ep center of mass energy, √s≅1.26 TeV. We invoke the boson-gluon fusion model to estimate theoretical cross sections and distributions for the heavy quarks. Higher order QCD corrections are only approximately taken into account, by assuming a (normalization) K-factor of 2 for the charm and beauty quark production rates and incorporating the parton shower cascades. With these assumptions and the parameterization of Eichten et al. for the structure functions (EHLQ, set 1), we find the following cross sections: σ(ep→c+X)≅O(3 μb), σ(ep→b+X)≅O(40 nb), and σ(ep→t+X)≅4 pb for m t =120 GeV, decreasing to 0.5 pb for m t =250 GeV. These cross sections would provide O(6x10 9 ) charmed hadrons, O(8x10 7 ) beauty hadrons, and O(10 3 ) top hadrons, for an integrated ep luminosity of 1000 pb -1 . The heavy quark rates in ep collisions are considerably smaller than the corresponding rates in pp collisions at LHC, with √s=16 TeV. This gives a clear advantage to pp collisions for top searches. However, for the charmed and beauty quarks only a tiny fraction of the cross sections in p+p→Q+X can be triggered in comparison to the corresponding cross sections in e+p→Q+X, resulting in comparable number of measured heavy quark events in the ep and pp mode. We sketch the energy-momentum profile of heavy quark events in ep collisions and illustrate the kind of analyses that experiments at the LEP+LHC collider would undertake to quantitatively study heavy quark physics. In particular, prospects of measuring the particle-antiparticle mixing parameter x s =ΔM/Γ for the B s 0 -anti B s 0 meson system are evaluated, and search strategies for the top quark in ep collisions are presented. (orig.)
Simulating at realistic quark masses. Light quark masses
International Nuclear Information System (INIS)
Goeckeler, M.; Streuer, T.
2006-11-01
We present new results for light quark masses. The calculations are performed using two flavours of O(a) improved Wilson fermions. We have reached lattice spacings as small as a ∝0.07 fm and pion masses down to m π ∝340 MeV in our simulations. This gives us significantly better control on the chiral and continuum extrapolations. (orig.)
New theoretical results in heavy quark hadroproduction
International Nuclear Information System (INIS)
Nason, P.
1992-01-01
We describe the status of the heavy quark hadroproduction theory. In particular, we discuss recent developments on production of heavy quarks in the high energy limit, and the results of a new calculation to next-to-leading accuracy of the fully exclusive parton cross section for heavy quark production. (orig.)
Quark fragmentation in e+e- collisions
International Nuclear Information System (INIS)
Oddone, P.
1984-12-01
This brief review of new results in quark and gluon fragmentation observed in e + e - collisions concentrates mostly on PEP results and, within PEP, mostly on TPC results. The new PETRA results have been reported at this conference by M. Davier. It is restricted to results on light quark fragmentation since the results on heavy quark fragmentation have been reported by J. Chapman
Planar quark diagrams and binary spin processes
International Nuclear Information System (INIS)
Grigoryan, A.A.; Ivanov, N.Ya.
1986-01-01
Contributions of planar diagrams to the binary scattering processes are analyzed. The analysis is based on the predictions of quark-gluon picture of strong interactions for the coupling of reggeons with quarks as well as on the SU(6)-classification of hadrons. The dependence of contributions of nonplanar corrections on spins and quark composition of interacting particles is discussed
Charm-quarks and new elementary particles
International Nuclear Information System (INIS)
Petersen, J.L.
1978-01-01
This is the first part of an extensive paper which discusses: the Nobel prize in physics 1976; discovery of the J/psi-particle; elementary particles and elementary building blocks; the four reciprocal effects; gauge theories; quark-antiquark reciprocal effects; the high-energy approximation; a simple quark-antiquark potential; and quark diagrams and the Zweig rule. (Auth.)
Variational approach to chiral quark models
Energy Technology Data Exchange (ETDEWEB)
Futami, Yasuhiko; Odajima, Yasuhiko; Suzuki, Akira
1987-03-01
A variational approach is applied to a chiral quark model to test the validity of the perturbative treatment of the pion-quark interaction based on the chiral symmetry principle. It is indispensably related to the chiral symmetry breaking radius if the pion-quark interaction can be regarded as a perturbation.
A variational approach to chiral quark models
International Nuclear Information System (INIS)
Futami, Yasuhiko; Odajima, Yasuhiko; Suzuki, Akira.
1987-01-01
A variational approach is applied to a chiral quark model to test the validity of the perturbative treatment of the pion-quark interaction based on the chiral symmetry principle. It is indispensably related to the chiral symmetry breaking radius if the pion-quark interaction can be regarded as a perturbation. (author)
Pole masses of quarks in dimensional reduction
International Nuclear Information System (INIS)
Avdeev, L.V.; Kalmykov, M.Yu.
1997-01-01
Pole masses of quarks in quantum chromodynamics are calculated to the two-loop order in the framework of the regularization by dimensional reduction. For the diagram with a light quark loop, the non-Euclidean asymptotic expansion is constructed with the external momentum on the mass shell of a heavy quark
The quark gluon plasma; Le plasma de quarks et de gluons
Energy Technology Data Exchange (ETDEWEB)
Granier de Cassagnac, R. [Ecole Polytechnique, Lab. Leprince-Ringuet, 91 - Palaiseau (France)
2010-05-15
The quark-gluon plasma (QGP) is a state of matter in which the universe was expected to be a few micro-seconds after the big-bang. Violent collisions of heavy ions are supposed to re-create this state in particle accelerators. Numerous signatures of this fugacious state have already been observed at the RHIC (relativistic heavy ion collider). The first evidence of the violence of collisions is the number of generated particles: about 6000 per collision, mostly hadrons. This figure seems high but in fact is less than theoretically expected and is the first sign of the formation of a QGP that saturates the density of gluons. Another sign, observed at the RHIC is the damping of the particle jets that are produced in the collision. This damping is consistent with the crossing of a medium whose density is so high that it can not be made of hadrons but of partons. In the RHIC experiments the collective behaviour of quarks and gluons shows that they are strongly interacting with one another. This fact supports the idea that the QGP is more a perfect liquid rather than an ideal gas in which quarks and gluons move freely. (A.C.)
International Nuclear Information System (INIS)
Hill, C.T.
1981-10-01
Exactly two years ago at the 1979 Lepton, Photon Symposium at Fermilab, Mary K. Gaillard presented a histogram showing the number of papers predicting a given value of toponium mass as a function of mass. I have translated this into the t-quark mass and presented it including several other bounds arising from an assortment of physical principles and arguments. These include Veltman's rho-parameter bound, a well-known bound from grand unification due to Cabibbo, Maiani, Parisi and Petronzio, and considerations of Higgs potential stability and unitarity. The central popular mechanism for generating t-quark mass predictions, you will recall, was to employ discrete symmetries in the Higgs sector of left-right symmetric models, leading to a central popular prediction of m approx. 15 GeV. It should be noted that discrete symmetries can lead to larger values (and smaller ones), but clearly with diminished unanimity. We should also mention independent ideas which presume a basic universal ratio of m/sup (+2/3)//m/sup (-1/3)/ for all generations and lead to a prediction of m approx. 26 GeV. In the intervening two years physicists have kept busy generating new t-quark mass predictions and Petra has pushed the lower bound up to approx. 18.5 GeV. New physical ideas have emerged which now focus more directly upon dynamical aspects of grand-unification. uv versus ir behavior of field theory, and nonlinear renormalization group equations with quasi-fixed point behavior. Some of these ideas make statements about hypothetical fourth generation fermion masses. These ideas are reviewed with an eye to statements one can make about mass scales beyond the third generation, as well
Charge asymmetry ratio as a probe of quark flavour couplings of resonant particles at the LHC
International Nuclear Information System (INIS)
Kom, Chun-Hay; Stirling, W.J.
2011-01-01
We show how a precise knowledge of parton distribution functions, in particular those of the u and d quarks, can be used to constrain a certain class of New Physics models in which new heavy charged resonances couple to quarks and leptons. We illustrate the method by considering a left-right symmetric model with a W' from a SU(2) R gauge sector produced in quark-antiquark annihilation and decaying into a charged lepton and a heavy Majorana neutrino. We discuss a number of quark and lepton mixing scenarios, and simulate both signals and backgrounds in order to determine the size of the expected charge asymmetry. We show that various quark-W' mixing scenarios can indeed be constrained by charge asymmetry measurements at the LHC, particularly at √(s)=14 TeV. (orig.)
Baryonic hybrids: Gluons as beads on strings between quarks
International Nuclear Information System (INIS)
Cornwall, John M.
2005-01-01
In this paper we analyze the ground state of the heavy-quark qqqG system using standard principles of quark confinement and massive constituent gluons as established in the center-vortex picture. The known string tension K F and approximately-known gluon mass M lead to a precise specification of the long-range nonrelativistic part of the potential binding the gluon to the quarks with no undetermined phenomenological parameters, in the limit of large interquark separation R. Our major tool (also used earlier by Simonov) is the use of proper-time methods to describe gluon propagation within the quark system, along with some elementary group theory describing the gluon Wilson-line as a composite of colocated q and q lines. We show that (aside from color-Coulomb and similar terms) the gluon potential energy in the presence of quarks is accurately described (for small gluon fluctuations) via attaching these three strings to the gluon, which in equilibrium sits at the Steiner point of the Y-shaped string network joining the three quarks. The gluon undergoes small harmonic fluctuations that slightly stretch these strings and quasiconfine the gluon to the neighborhood of the Steiner point. To describe nonrelativistic ground-state gluonic fluctuations at large R we use the Schroedinger equation, ignoring mixing with l=2 states. Available lattice data and real-world hybrids require consideration of R values small enough for significant relativistic corrections, which we apply using a variational principle for the relativistic harmonic-oscillator. We also consider the role of color-Coulomb contributions. In terms of interquark separations R, we find leading nonrelativistic large-R terms in the gluon excitation energy of the form ε(R)→M+ξ[K F /(MR)] 1/2 -ζα c /R where ξ,ζ are calculable numerical coefficients and α c ≅ 0.15 is the color-Coulomb qq coupling. When the gluon is relativistic, ε∼(K F /R) 1/3 . We get an acceptable fit to lattice data with M=500 Me
Fragmentation of quarks and gluons
International Nuclear Information System (INIS)
Soeding, P.
1983-10-01
The author presents a review about quark and gluon jets. He describes the particle contents of the different types of jets. Finally he considers the hadronization mechanism with special regards to three-jet events in e + e - annihilation and hadronization in nuclear matter. (HSI)
Quarks, history of a discovery
International Nuclear Information System (INIS)
Husson, D.
2000-01-01
This book gives a presentation of quarks and stresses on the historical aspects of the studies that led to their discovery. The 'aesthetical' motivations of the scientists in their research are explained with only a minimum of mathematical concepts. (J.S.)
Phase space quark counting rule
International Nuclear Information System (INIS)
Wei-gin, C.; Lo, S.
1980-01-01
A simple quark counting rule based on phase space consideration suggested before is used to fit all 39 recent experimental data points on inclusive reactions. Parameter free relations are found to agree with experiments. Excellent detail fits are obtained for 11 inclusive reactions
Correlations among static quark masses
International Nuclear Information System (INIS)
Lewin, K.; Motz, G.B.
1987-01-01
Nonrelativistic heavy quarkonia potentials with Coulomb and linearly rising limiting behaviour are correlated additively by Taylor expansion extracting the limiting structure and a constant term. Relations between fit parameters of different potentials including the quark masses m b and m c , are obtained. The known stability of the difference m b -m c , appears as direct consequence of flavour invariance of the potentials
1995-01-01
This is a sequel to the review volume Quark-Gluon Plasma. There are 13 articles contributed by leading investigators in the field, covering a wide range of topics about the theoretical approach to the subject. These contributions are timely reviews of nearly all the actively pursued problems, written in a pedagogical style suitable for beginners as well as experienced researchers.
Quark Matter '87: Concluding remarks
International Nuclear Information System (INIS)
Gyulassy, M.
1988-03-01
This year marked the beginning of the experimental program at BNL and CERN to probe the properties of ultra dense hadronic matter and to search for the quark-gluon plasma phase of matter. Possible implications of the preliminary findings are discussed. Problems needing further theoretical and experimental study are pointed out. 50 refs
Kim, S. B.
1995-08-01
Top quark production is observed in{bar p}p collisions at{radical}s= 1.8 TeV at the Fermilab Tevatron. The Collider Detector at Fermilab (CDF) and D{O} observe signals consistent with t{bar t} to WWb{bar b}, but inconsistent with the background prediction by 4.8{sigma} (CDF), 4.6a (D{O}). Additional evidence for the top quark Is provided by a peak in the reconstructed mass distribution. The kinematic properties of the excess events are consistent with the top quark decay. They measure the top quark mass to be 176{plus_minus}8(stat.){plus_minus}10(sys.) GeV/c{sup 2} (CDF), 199{sub -21}{sup+19}(stat.){plus_minus}22(sys.) GeV/c{sup 2} (D{O}), and the t{bar t} production cross section to be 6.8{sub -2.4}{sup+3.6}pb (CDF), 6.4{plus_minus}2.2 pb (D{O}).
Hydrodynamics of a quark droplet
DEFF Research Database (Denmark)
Bjerrum-Bohr, Johan J.; Mishustin, Igor N.; Døssing, Thomas
2012-01-01
We present a simple model of a multi-quark droplet evolution based on the hydrodynamical description. This model includes collective expansion of the droplet, effects of the vacuum pressure and surface tension. The hadron emission from the droplet is described following Weisskopf's statistical...
Young, Robert D.
1973-01-01
Discusses the charge independence, wavefunctions, magnetic moments, and high-energy scattering of hadrons on the basis of group theory and nonrelativistic quark model with mass spectrum calculated by first-order perturbation theory. The presentation is explainable to advanced undergraduate students. (CC)
2003-01-01
Fitted with new state-of-the-art silicon detectors, NA60 is prepared to study the phase transition from confined hadronic matter to a deconfined (free) quark-gluon plasma, a state of matter which probably existed an instant after the Big Bang.
Vogt, Ramona
1998-01-01
Aspects of quark-gluon plasma signatures that can be measured by CMS are discussed. First the initial conditions of the system from minijet production are introduced, including shadowing effects. Color screening of the Upsilon family is then presented, followed by energy loss effects on charm and bottom hadrons, high Pt jets and global observables.
Brown, Laurie Mark; Dresden, Max; Hoddeson, Lillian
2009-01-01
Part I. Introduction; 1. Pions to quarks: particle physics in the 1950s Laurie M Brown, Max Dresden and Lillian Hoddeson; 2. Particle physics in the early 1950s Chen Ning Yang; 3. An historian's interest in particle physics J. L. Heilbron; Part II. Particle discoveries in cosmic rays; 4. Cosmic-ray cloud-chamber contributions to the discovery of the strange particles in the decade 1947-1957 George D. Rochester; 5. Cosmic-ray work with emulsions in the 1940s and 1950s Donald H. Perkins; Part III. High-energy nuclear physics; Learning about nucleon resonances with pion photoproduction Robert L. Walker; 7. A personal view of nucleon structure as revealed by electron scattering Robert Hofstadter; 8. Comments on electromagnetic form factors of the nucleon Robert G. Sachs and Kameshwar C. Wali; Part IV. The new laboratory; 9. The making of an accelerator physicist Matthew Sands; 10. Accelerator design and construction in the 1950s John P. Blewett; 11. Early history of the Cosmotron and AGS Ernest D. Courant; 12. Panel on accelerators and detectors in the 1950s Lawrence W. Jones, Luis W. Alvarez, Ugo Amaldi, Robert Hofstadter, Donald W. Kerst, Robert R. Wilson; 13. Accelerators and the Midwestern Universities Research Association in the 1950s Donald W. Kerst; 14. Bubbles, sparks and the postwar laboratory Peter Galison; 15. Development of the discharge (spark) chamber in Japan in the 1950s Shuji Fukui; 16. Early work at the Bevatron: a personal account Gerson Goldhaber; 17. The discovery of the antiproton Owen Chamberlain; 18. On the antiproton discovery Oreste Piccioni; Part V. The Strange Particles; 19. The hydrogen bubble chamber and the strange resonances Luis W. Alvarez; 20. A particular view of particle physics in the fifties Jack Steinberger; 21. Strange particles William Chinowsky; 22. Strange particles: production by Cosmotron beams as observed in diffusion cloud chambers William B. Fowler; 23. From the 1940s into the 1950s Abraham Pais; Part VI. Detection of the
Directory of Open Access Journals (Sweden)
Jeong Kim Tae
2014-04-01
Full Text Available In 2011, an integrated luminosity of more than 5 fb−1 at 7 TeV has been delivered by the LHC. The measurement of the cross section in top quark pair production and in single top quark production, top quark mass, top quark properties and new physics searches in top quark decays have been performed at the CMS experiment with various integrated luminosities. An overview of the latest results of these measurements and searches by the time of ICFP 2012 conference will be presented.
Analysis of gamma irradiated pepper constituents, 2
International Nuclear Information System (INIS)
Takagi, Kazuko; Ochiai, Junko; Okuyama, Tsuneo
1988-01-01
Black pepper, white pepper, frozen green pepper and real pink pepper (kept in vinegar) were analyzed by reversed phase IIPLC. The extraction method and HPLC conditions were same as the first report, that is, the extraction from pepper was performed by Automatic Air Hammer and the extracted samples were separated on a reversed phase C 8 column with a concave gradient from 0.1% trifluoro aceticacid (TFA) in water to 75% acetonitrile - 0.1% TFA in water for 60 minutes and detected at 210 nm, 280 nm. The different constituents were observed clearly on chromatogram between black pepper and white pepper. The different constituents were observed between different producing white peppers, and as the result that the analyzed pepper was distinguished its producing district by HPLC chromatogram. In order to investigate of effect of lyophilization on white pepper extracts, lyophilized extraction was analyzed by this HPLC method. Some peaks were decreased by lyophilization. The effect of heat on white pepper constituents was examined. White pepper was heated by electronic oven and thermostat. When the former method was used, decreased peak number (peak height was lower than without heat treatment) was more than latter method. These subtle change was able to be recognized by these HPLC chromatograms. (author)
[Chemical constituents in Buddleja albiflora].
Tao, Liang; Huang, Jincheng; Zhao, Yanping; Li, Chong
2009-12-01
To study the chemical constituents of Buddleja albiflora. The constituents were isolated by column chromatography and their structures were elucidated by spectroscopic methods. Eleven compounds were isolated and identified as luteolin (1), quercetin (2), quercetin-3-O-beta-D-glucopyranoside (3), apigenin (4), apigenin-7-O-beta-D-glucopyranoside (5), apigenin-7-O-neohesperidoside (6), acacetin-7-O-beta-L-rhamnopyranosyl-(1-6)-beta-D-glucopyranoside (7), cranioside A (8), acetylmartynoside B (9), 4"-O-acetylmartynoside (10), isomartynoside (11). All these compounds were obtained from B. albiflora for the first time and compound 8 was obtained from the genus Buddleja for the first time.
KN scattering in the nonrelativistic quark model
International Nuclear Information System (INIS)
Barnes, F.E.
1995-01-01
KN scattering is of interest as a probe of nuclear structure and, more fundamentally, as a laboratory for the study of nonresonant hadron-hadron interactions. KN is a I theoretically attractive channel because of its simplicity, having only S = 1/2, no one pion exchange contributions and no valence q anti q annihilation. It may therefore be useful for the study of short-ranged quark forces analogous to the NN repulsive core. Since there are two isospin states, comparison of two closely related amplitudes is possible. This contribution reviews the experimental status of S-wave KN scattering and related theoretical studies based on quark-gluon dynamics. The experimental low-energy S-wave phase shift is well established for I = 1, but is not yet well determined for I = 0. The ratio of I = 0 to I = 1 scattering lengths is an interesting number theoretically, and may discriminate between different scattering mechanisms. A measurement of these scattering lengths at DAPHNE would be a useful contribution to low energy hadron physics
On the quark structure of resonance states in dual models
International Nuclear Information System (INIS)
Volkov, D.V.; Zheltukhin, A.A.; Pashnev, A.I.
1975-01-01
It is shown using as an example the Veneziano dual model, that each particular dual model already contains a certain latent quark structure unambiauously determined by internal properties of the dual model. To prove this degeneration of the resonance state spectrum is studied by introducing an additional disturbing interaction into the model being considered. Induced transitions of particles into a vacuum act as such an additional disturbance. This method complements the known factorization method of Fubini, Gordon and Veneziano and turns out to be free from an essential limitation of the latter connected with implicit assumption about the basence of internal additive laws of conservation in the model. By using the method of induced transitions of particles into a vacuum it has been possible to show that the resonance state spectrum is indeed more degenerated than it should be expected from the factorization theorem, and that the supplementary degeneration corresponds to the quark model with an infinite number of quarks of the increasing mass. Structures of some terms of the dual amplitude expansion over the degrees of the constant of the induced transition of particles to vacuum are considered; it is shown that the summation of this expansion may be reduced to a solution of a certain integral equation. On the basis of the integral equation obtained an integral representation ofr dual amplitudes is established. The problems related with degeneration of resonance states and with determination of additive quantum numbers leading to the quark interpretation of the degeneration being considered are discussed
The effect of dynamical quark mass on the calculation of a strange quark star's structure
Institute of Scientific and Technical Information of China (English)
Gholam Hossein Bordbar; Babak Ziaei
2012-01-01
We discuss the dynamical behavior of strange quark matter components,in particular the effects of density dependent quark mass on the equation of state of strange quark matter.The dynamical masses of quarks are computed within the Nambu-Jona-Lasinio model,then we perform strange quark matter calculations employing the MIT bag model with these dynamical masses.For the sake of comparing dynamical mass interaction with QCD quark-quark interaction,we consider the one-gluon-exchange term as the effective interaction between quarks for the MIT bag model.Our dynamical approach illustrates an improvement in the obtained equation of state values.We also investigate the structure of the strange quark star using TolmanOppenheimer-Volkoff equations for all applied models.Our results show that dynamical mass interaction leads to lower values for gravitational mass.
Simulating at realistic quark masses. Light quark masses
Energy Technology Data Exchange (ETDEWEB)
Goeckeler, M. [Regensburg Univ. (Germany). Inst. fuer Physik 1 - Theoretische Physik; Horsley, R.; Zanotti, J.M. [Edinburgh Univ. (United Kingdom). School of Physics; Nakamura, Y.; Pleiter, D. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Dept. of Mathematical Sciences; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC]|[Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Streuer, T. [Kentucky Univ., Lexington, KY (United States). Dept. of Physics and Astronomy; Stueben, H. [Konrad-Zuse-Zentrum fuer Informationstechnik Berlin (ZIB) (Germany)
2006-11-15
We present new results for light quark masses. The calculations are performed using two flavours of O(a) improved Wilson fermions. We have reached lattice spacings as small as a {proportional_to}0.07 fm and pion masses down to m{sub {pi}} {proportional_to}340 MeV in our simulations. This gives us significantly better control on the chiral and continuum extrapolations. (orig.)
Antifungal constituents of Melicope borbonica
DEFF Research Database (Denmark)
Simonsen, Henrik Toft; Adsersen, Anne; Bremner, Paul
2004-01-01
-methoxycoumarin, cedrelopsin and psoralen], two sesquiterpenes (alpha-curcumene and 3,6-epidioxy-1,10-bisaboladiene), eugenol, methyleugenol and a lignan (sesamin) were isolated. None of the isolated constituents exhibited antiin fl ammatory activity in vitro. No alkaloids were detected....
Energy Technology Data Exchange (ETDEWEB)
Nejad, S.M.M. [Yazd University, Faculty of Physics, P.O. Box 89195-741, Yazd (Iran, Islamic Republic of); Institute for Research in Fundamental Sciences (IPM), School of Particles and Accelerators, P.O.Box 19395-5531, Tehran (Iran, Islamic Republic of); Balali, Mahboobe [Yazd University, Faculty of Physics, P.O. Box 89195-741, Yazd (Iran, Islamic Republic of)
2016-03-15
We present the analytical expressions for the next-to-leading order corrections to the partial decay width t(↑) → bW{sup +}, followed by b @→ H{sub b}X, for nonzero b-quark mass (m{sub b} ≠ 0) in the fixed-flavor-number scheme (FFNs). To make the predictions for the energy distribution of outgoing hadrons H{sub b}, as a function of the normalized H{sub b}-energy fraction x{sub H}, we apply the general-mass variable-flavor-number scheme (GM-VFNs) in a specific helicity coordinate system where the polarization of top quark is evaluated relative to the b-quark momentum. We also study the effects of gluon fragmentation and finite hadron mass on the hadron energy spectrum so that hadron masses are responsible for the low x{sub H} threshold. In order to describe both the b-quark and the gluon hadronizations in top decays we apply realistic and nonperturbative fragmentation functions extracted through a global fit to the e{sup +}e{sup -} annihilation data from CERN LEP1 and SLAC SLC by relying on their universality and scaling violations. (orig.)
QCD phase transition with chiral quarks and physical quark masses.
Bhattacharya, Tanmoy; Buchoff, Michael I; Christ, Norman H; Ding, H-T; Gupta, Rajan; Jung, Chulwoo; Karsch, F; Lin, Zhongjie; Mawhinney, R D; McGlynn, Greg; Mukherjee, Swagato; Murphy, David; Petreczky, P; Renfrew, Dwight; Schroeder, Chris; Soltz, R A; Vranas, P M; Yin, Hantao
2014-08-22
We report on the first lattice calculation of the QCD phase transition using chiral fermions with physical quark masses. This calculation uses 2+1 quark flavors, spatial volumes between (4 fm)(3) and (11 fm)(3) and temperatures between 139 and 196 MeV. Each temperature is calculated at a single lattice spacing corresponding to a temporal Euclidean extent of N(t) = 8. The disconnected chiral susceptibility, χ(disc) shows a pronounced peak whose position and height depend sensitively on the quark mass. We find no metastability near the peak and a peak height which does not change when a 5 fm spatial extent is increased to 10 fm. Each result is strong evidence that the QCD "phase transition" is not first order but a continuous crossover for m(π) = 135 MeV. The peak location determines a pseudocritical temperature T(c) = 155(1)(8) MeV, in agreement with earlier staggered fermion results. However, the peak height is 50% greater than that suggested by previous staggered results. Chiral SU(2)(L) × SU(2)(R) symmetry is fully restored above 164 MeV, but anomalous U(1)(A) symmetry breaking is nonzero above T(c) and vanishes as T is increased to 196 MeV.
Results on top-quark physics and top-quark-like signatures by CMS
Chabert, Eric; CMS Collaboration
2017-07-01
This report reviews the results obtained by the CMS Collaboration on top quark physics, focusing on the latest ones based on p-p collisions provided by the LHC at \\sqrt{s}=13{{TeV}} during Run II. It covers measurements of single-top, top quark pairs and associated productions as well as measurements of top quark properties. Finally several beyond the standard model searches involving top quark in the final states are presented, such as searches for supersymmetry in the third generation, heavy resonances decaying into a top quark pair, or dark matter produced in association to a single-top or a top quark pair.
Hadron matrix elements of quark operators in the relativistic quark model, 2. Model calculation
Energy Technology Data Exchange (ETDEWEB)
Arisue, H; Bando, M; Toya, M [Kyoto Univ. (Japan). Dept. of Physics; Sugimoto, H
1979-11-01
Phenomenological studies of the matrix elements of two- and four-quark operators are made on the basis of relativistic independent quark model for typical three cases of the potentials: rigid wall, linearly rising and Coulomb-like potentials. The values of the matrix elements of two-quark operators are relatively well reproduced in each case, but those of four-quark operators prove to be too small in the independent particle treatment. It is suggested that the short-range two-quark correlations must be taken into account in order to improve the values of the matrix elements of the four-quark operators.
DEFF Research Database (Denmark)
Thrane, Torben
2004-01-01
Taking language as a special, second-order representational system, the article explores some consequences of this view for syntactico-semantic analysis, in particular for the notion of argument structure.......Taking language as a special, second-order representational system, the article explores some consequences of this view for syntactico-semantic analysis, in particular for the notion of argument structure....
General structure of democratic mass matrix of quark sector in E{sub 6} model
Energy Technology Data Exchange (ETDEWEB)
Ciftci, R., E-mail: rciftci@cern.ch [Ankara (Turkey); Çiftci, A. K., E-mail: abbas.kenan.ciftci@cern.ch [Ankara University, Ankara (Turkey)
2016-03-25
An extension of the Standard Model (SM) fermion sector, which is inspired by the E{sub 6} Grand Unified Theory (GUT) model, might be a good candidate to explain a number of unanswered questions in SM. Existence of the isosinglet quarks might explain great mass difference of bottom and top quarks. Also, democracy on mass matrix elements is a natural approach in SM. In this study, we have given general structure of Democratic Mass Matrix (DMM) of quark sector in E6 model.
Quark interactions and colour chemistry
International Nuclear Information System (INIS)
Hong-Mo, C.
1982-01-01
The interaction between quarks, according to the current theory of quantum chromodynamics, is similar to the electromagnetic interaction between electrons and nucleons, both being governed by locally gauge-invariant field theories. It is tempting therefore to discuss the spectroscopy of hadrons, which are quark composites bound by colour forces, in the same language as the spectroscopy of atoms and molecules which are bound states of electrons and nucleons held together by e.m. forces. Because of the difference in gauge groups, however, the dynamics are very different. Nonetheless, it appears likely that metastable multiquark hadron states can exist which are analogous to atoms and molecules in QED. In these lectures, tentative steps are taken in developing the rudiments of a new colour chemistry' of these 'atoms' and 'molecules'. (author)
International Nuclear Information System (INIS)
Oset, E.
1980-01-01
A short review of the topic of mesons in nuclei is exposed paying particular attention to the relationship between several mesonic processes. Special emphasis is put into the microscopic pictures that can ultimately relate all these processes with the elementary coupling of mesons to the nuclear hadronic components. The importance of the short range part of the nuclear interaction opens the doors to a more basic understanding in terms of the quark components of nucleons and isobars. (orig.)
Walsh, Karen McNulty
2011-03-28
Near-light-speed collisions of gold ions provide a recipe for in-depth explorations of matter and fundamental forces. The Relativistic Heavy Ion Collider (RHIC) has produced the most massive antimatter nucleus ever discovered?and the first containing an anti-strange quark. The presence of strange antimatter makes this antinucleus the first to be entered below the plane of the classic Periodic Table of Elements, marking a new frontier in physics.
Spin interactions of light quarks
International Nuclear Information System (INIS)
Simonov, Yu.A.
1989-01-01
Spin-spin and spin-orbit interactions of light quarks is calculated exactly, i.e. without use of perturbation expansion in (mass) -1 . Vacuum gluonic fields are represented by bilocal correlators and higher order correlators are neglected. Perturbative contribution is reproduced in lowest order by a simple modification of the bilocal correlator, and the smearing of the function in the hyperfine term is discussed. 12 refs
Directory of Open Access Journals (Sweden)
Reimer Paul E
2016-01-01
Full Text Available The proton is a composite particle in which the binding force is responsible for the majority of its mass. To understand this structure, the distributions and origins of the quark-antiquark pairs produced by the strong force must be measured. The SeaQuest collaboration is using the Drell-Yan process to elucidate antiquark distributions in the proton and to study their modification when the proton is held within a nucleus.
Quarks in high energy interactions
International Nuclear Information System (INIS)
Landshoff, P.V.
1978-01-01
The great interest of the quark parton model is that is seems to provide a successful way of relating together a variety of apparently very different reactions. In these lectures the author reviews the principal applications of the model. The following reactions are discussed: 1) Deep inelastic scattering of electrons, muons and neutrinos, 2) Production of lepton pairs, J/psi and W in hadronic collisions, 3) Electron-positron annihilation, 4) Large transverse momentum hadronic processes. (Auth.)
A Study of Quark Fragmentation Using Kaons Produced in Association with Prompt $D_s^±/D^±$ Mesons
Energy Technology Data Exchange (ETDEWEB)
Singh, Niharika Ranjan [Purdue Univ., West Lafayette, IN (United States)
2012-01-01
Quarks are considered to be the fundamental constituents of hadronic matter, but they have never been observed as free particles. When quarks are produced at high energy colliders, they quickly form bound colorless states, which then decay to produce the particles observed in experiments. The process by which an initially free quark combines with other quarks to form a hadronic particle is called quark fragmentation and has been described using phenomenological models since quarks were first proposed. Since then, several models have been developed to describe the quark fragmentation phenomenon, and these have been tuned to reproduce many average properties of hadrons produced in high energy collisions. In this dissertation, we describe an analysis that probes the properties of particles produced in association with a hadron containing a charm quark that provides a way, for the first time, to study what is thought of as the second particle produced in the process of heavy quar k fragmentation. Data from proton anti-proton collisions was used to carry out this research, which were collected with the CDF II detector at the Fermilab Tevatron and corresponds to 360/pb^{-1} of integrated luminosity. We reconstruct $D_s^±$ and $D^±$ mesons, which contain charm quarks, and identify the kaons produced in association with them. The kinematic properties of these kaons are compared with predictions of the fragmentation models implemented in the PYTHIA and HERWIG event generators. We find that kaon production in association with $D_s^±$ mesons is enhanced at levels that are in agreement with the fragmentation models but observe differences in production rates of kaons that are produced later in the fragmentation process.
Heavy quark and sparticle phenomenology
International Nuclear Information System (INIS)
Barger, V.
1985-01-01
Data from the CERN p anti p collider provide a new avenue for the study of heavy-quark production and possibly also provide the first indication for the sparticles of supersymmetry. This discussion of the associated phenomenology begins with charm and bottom quarks, proceeds to the strategies that lead to top quark identification, and concludes with possible supersymmetry scenarios to explain the events observed by the UA1 collaboration with large missing transverse momentum. The fusion predictions of single muon and dimuon rates are in the ballpark of UA1 observations. The discovery of isolated like-sign dimuons is at present an anomaly. The p anti p collider is a good place to do B physics, and answer the question of whether B 0 - anti B 0 mixing occurs. Also, it should soon be possible to identify a few dimuon events of W → t anti b and t anti t origins. Finally, enhanced charm in jets, if established, would have to be ascribed to non-perturbative QCD effects. In conclusion, if the UA1 monojets are of supersymmetry origin, then squark and gluino masses are already tightly constrained and dijet events with large missing transverse momentum should help distinguish between the two most promising scenarios. The top signal is not being faked by sparticles. (Nogami, K.)
PEP quark search proportional chambers
Energy Technology Data Exchange (ETDEWEB)
Parker, S I; Harris, F; Karliner, I; Yount, D [Hawaii Univ., Honolulu (USA); Ely, R; Hamilton, R; Pun, T [California Univ., Berkeley (USA). Lawrence Berkeley Lab.; Guryn, W; Miller, D; Fries, R [Northwestern Univ., Evanston, IL (USA)
1981-04-01
Proportional chambers are used in the PEP Free Quark Search to identify and remove possible background sources such as particles traversing the edges of counters, to permit geometric corrections to the dE/dx and TOF information from the scintillator and Cerenkov counters, and to look for possible high cross section quarks. The present beam pipe has a thickness of 0.007 interaction lengths (lambdasub(i)) and is followed in both arms each with 45/sup 0/ <= theta <= 135/sup 0/, ..delta..phi=90/sup 0/ by 5 proportional chambers, each 0.0008 lambdasub(i) thick with 32 channels of pulse height readout, and by 3 thin scintillator planes, each 0.003 lambdasub(i) thick. Following this thin front end, each arm of the detector has 8 layers of scintillator (one with scintillating light pipes) interspersed with 4 proportional chambers and a layer of lucite Cerenkov counters. Both the calculated ion statistics and measurements using He-CH/sub 4/ gas in a test chamber indicate that the chamber efficiencies should be >98% for q=1/3. The Landau spread measured in the test was equal to that observed for normal q=1 traversals. One scintillator plane and thin chamber in each arm will have an extra set of ADC's with a wide gate bracketing the normal one so timing errors and tails of earlier pulses should not produce fake quarks.
Quark cluster model and confinement
International Nuclear Information System (INIS)
Koike, Yuji; Yazaki, Koichi
2000-01-01
How confinement of quarks is implemented for multi-hadron systems in the quark cluster model is reviewed. In order to learn the nature of the confining interaction for fermions we first study 1+1 dimensional QED and QCD, in which the gauge field can be eliminated exactly and generates linear interaction of fermions. Then, we compare the two-body potential model, the flip-flop model and the Born-Oppenheimer approach in the strong coupling lattice QCD for the meson-meson system. Having shown how the long-range attraction between hadrons, van der Waals interaction, shows up in the two-body potential model, we discuss two distinct attempts beyond the two-body potential model: one is a many-body potential model, the flip-flop model, and the other is the Born-Oppenheimer approach in the strong coupling lattice QCD. We explain how the emergence of the long-range attraction is avoided in these attempts. Finally, we present the results of the application of the flip-flop model to the baryon-baryon scattering in the quark cluster model. (author)
Do bound color octet states of liberated quarks exist
International Nuclear Information System (INIS)
Lipkin, H.J.
1979-01-01
In models where quarks are liberated and color can be excited, the three-quark color-octet state is shown to be unbound and unstable against breakup into free quarks and diquarks. The signature for color excitation in deep inelastic processes will not be a bound three-quark state which decays electromagnetically but a final state containing free quarks. (author)
Impact of the heavy quark matching scales in PDF fits
Energy Technology Data Exchange (ETDEWEB)
Bertone, V. [VU Univ., Amsterdam (Netherlands). Dept. of Physics and Astronomy; Nikhef Theory Goup, Amsterdam (Netherlands); Britzger, D. [DESY, Hamburg (Germany); Camarda, S. [CERN, Geneva (Switzerland); Collaboration: The xFitter Developers' Team; and others
2017-07-15
We investigate the impact of displaced heavy quark matching scales in a global fit. The heavy quark matching scale μ{sub m} determines at which energy scale μ the QCD theory transitions from N{sub F} to N{sub F}+1 in the Variable Flavor Number Scheme (VFNS) for the evolution of the Parton Distribution Functions (PDFs) and strong coupling α{sub S}(μ). We study the variation of the matching scales, and their impact on a global PDF fit of the combined HERA data. As the choice of the matching scale μ{sub m} effectively is a choice of scheme, this represents a theoretical uncertainty; ideally, we would like to see minimal dependence on this parameter. For the transition across the charm quark (from N{sub F}=3 to 4), we find a large μ{sub m}=μ{sub c} dependence of the global fit χ{sup 2} at NLO, but this is significantly reduced at NNLO. For the transition across the bottom quark (from N{sub F}=4 to 5), we have a reduced μ{sub m}=μ{sub b} dependence of the χ{sup 2} at both NLO and NNLO as compared to the charm. This feature is now implemented in xFitter 2.0.0, an open source QCD fit framework.
Quark contact interactions at the LHC
Bazzocchi, F.; De Sanctis, U.; Fabbrichesi, M.; Tonero, A.
2012-06-01
Quark contact interactions are an important signal of new physics. We introduce a model in which the presence of a symmetry protects these new interactions from giving large corrections in flavor changing processes at low energies. This minimal model provides the basic set of operators which must be considered to contribute to the high-energy processes. To discuss their experimental signature in jet pairs produced in proton-proton collisions, we simplify the number of possible operators down to two. We show (for a representative integrated luminosity of 200pb-1 at s=7TeV) how the presence of two operators significantly modifies the bound on the characteristic energy scale of the contact interactions, which is obtained by keeping a single operator.
Quark number density and susceptibility calculation under one-loop ...
Indian Academy of Sciences (India)
Author Affiliations. S SOMORENDRO SINGH1 G SAXENA2. Department of Physics and Astrophysics, University of Delhi, Delhi 110 007, India; Physics Department, Government Women Engineering College, Ajmer 305 002, India ...
Quark number density and susceptibility calculation under one loop ...
Indian Academy of Sciences (India)
S Somorendro Singh
2017-05-30
May 30, 2017 ... other experimental facilities like FAIR at Darmstadt and ... can provide information of QCD phase structure. To ... the mean-field potential through coupling value [9– .... The results are very consistent with the current results.
Vector Susceptibility of QCD Vacuum from an Effective Quark-Quark Interaction
Institute of Scientific and Technical Information of China (English)
ZONG Hong-Shi; QI Shi; CHEN Wei; WU Xiao-Hua
2003-01-01
.A new approach for calculating vacuum susceptibilities from an effective quark-quark interaction model is derived. As a special case, the vector vacuum susceptibility is calculated. A comparison with the results of the previous approaches is given.
Comment on ``Brown dwarfs, quark stars, and quark-hadron phase transition``
Energy Technology Data Exchange (ETDEWEB)
Kubis, S.; Kutschera, M. [Institute of Nuclear Physics, Cracow (Poland)
1995-12-01
It is shown that the cosmological quark-hadron phase transition within the Lee-Wick model with a high degree of supercooling cannot be completed. No quark stars could be produced in this scenario. (author). 2 refs.
Comment on ''Brown dwarfs, quark stars, and quark-hadron phase transition''
International Nuclear Information System (INIS)
Kubis, S.; Kutschera, M.
1995-12-01
It is shown that the cosmological quark-hadron phase transition within the Lee-Wick model with a high degree of supercooling cannot be completed. No quark stars could be produced in this scenario. (author). 2 refs
The significance of the heavy top quark
International Nuclear Information System (INIS)
Simmons, Elizabeth H.
1997-01-01
Experiment shows that the top quark is far heavier than the other elementary fermions. This finding has stimulated research on theories of electroweak and flavor symmetry breaking that include physics beyond the standard model. Efforts to accommodate a heavy top quark within existing frameworks have revealed constraints on model-building. Other investigations have started from the premise that a large top quark mass could signal a qualitative difference between the top quark and other fermions, perhaps in the form of new interactions peculiar to the top quark. Such new dynamics may also help answer existing questions about electroweak and flavor physics. This talk explores the implications of the heavy top quark in the context of weakly-coupled (e.g., SUSY) and strongly-coupled (e.g., technicolor) theories of electroweak symmetry breaking
Top quark physics in ATLAS (CORFU 2014)
Moreno Llácer, M; The ATLAS collaboration
2014-01-01
The top quark is the heaviest elementary particle observed to date. Being heavier than a W boson, it is the only quark that decays weakly, i.e. into a real W boson and a b quark, before hadronization can occur. In addition, it is the only quark whose Yukawa coupling to the Higgs boson is order of unity. For these reasons the top quark plays a special role in the Standard Model of Particle Physics and in many of its extensions. An accurate knowledge of its properties (mass, couplings, production cross section, decay branching ratios, etc.) can bring key information on fundamental interactions at the electroweak breaking scale and beyond. In this talk the latest measurements of the characteristics of the top quark carried out in the ATLAS experiment at the Large Hadron Collider are presented.
Quark matter in a chiral chromodielectric model
International Nuclear Information System (INIS)
Broniowski, W.; Kutschera, M.; Cibej, M.; Rosina, M.
1989-03-01
Zero and finite temperature quark matter is studied in a chiral chromodielectric model with quark, meson and chromodielectric degrees of freedom. Mean field approximation is used. Two cases are considered: two-flavor and three-flavor quark matter. It is found that at sufficiently low densities and temperatures the system is in a chirally broken phase, with quarks acquiring effective masses of the order of 100 MeV. At higher densities and temperatures a chiral phase transition occurs and the quarks become massless. A comparison to traditional nuclear physics suggests that the chirally broken phase with massive quark gas may be the ground state of matter at densities of the order of a few nuclear saturation densities. 24 refs., 5 figs. (author)
Energy Technology Data Exchange (ETDEWEB)
Barik, N; Das, M [Utkal Univ., Bhubaneswar (India). Dept. of Physics
1983-01-13
Several properties of octet baryons such as (i) the magnetic moment, (ii) (Gsub(A)/Gsub(v))sub(n) for neutron ..beta..-decay and (iii) the charge radius of the proton have been calculated in a simple independent-quark model under the assumption that the individual constituent quarks are confined, in first approximation, by a relativistic power-law potential Vsub(q)(r)=(1+..beta..) (asup(..nu..+1)rsup(..nu..)+V/sub 0/) with a, ..nu..>0. In view of the simplicity of the model, the results obtained are quite encouraging.
International Nuclear Information System (INIS)
Barik, N.; Das, M.
1983-01-01
Several properties of octet baryons such as (i) the magnetic moment, (ii) (Gsub(A)/Gsub(v))sub(n) for neutron #betta#-decay and (iii) the charge radius of the proton have been calculated in a simple independent-quark model under the assumption that the individual constituent quarks are confined, in first approximation, by a relativistic power-law potential Vsub(q)(r)=(1+#betta#) (asup(#betta#+1)rsup(#betta#)+V 0 ) with a, #betta#>0. In view of the simplicity of the model, the results obtained are quite encouraging. (orig.)
Top Quark Production at Hadron Colliders
Energy Technology Data Exchange (ETDEWEB)
Phaf, Lukas Kaj [Univ. of Amsterdam (Netherlands)
2004-03-01
This thesis describes both theoretical and experimental research into top quark production. The theoretical part contains a calculation of the single-top quark production cross section at hadron colliders, at Next to Leading Order (NLO) accuracy. The experimental part describes a measurement of the top quark pair production cross section in proton-antiproton collisions, at a center of mass energy of 1.96 TeV.
Phenomenology of heavy leptons and heavy quarks
International Nuclear Information System (INIS)
Gilman, F.J.
1978-11-01
The review of the quark and lepton family includes properties of the tau, SU(2) x U(1) classification of the tau and its decays, heavier leptons, the spectroscopy of heavy hadrons composed of quarks, their strong and electromagnetic decays, the weak interaction properties of the c, b, and t quarks, and the decays of hadrons containing them expected within the context of the standard SU(2) x U(1) model. 76 references
Heavy quarks and their experimental consequences
International Nuclear Information System (INIS)
Appelquist, T.
1975-09-01
Recent theoretical work on heavy quark dynamics is reviewed. In the context of a color gauge theory of strong interactions, the structure of heavy quark-antiquark bound states and their decay properties is discussed. The emphasis is on the dynamical differences between heavy and light quark bound states. It is suggested that the former will more directly reflect the structure of the underlying field theory
QCD thermodynamics with two flavors of quarks
International Nuclear Information System (INIS)
Bernard, C.; Ogilvie, M.C.; DeGrand, T.A.; DeTar, C.; Gottlieb, S.; Krasnitz, A.; Sugar, R.L.; Toussaint, D.
1992-01-01
We present results of numerical simulations of quantum chromo-dynamics at finite temperature on the Intel iPSC/860 parallel processor. We performed calculations with two flavors of Kogut-Susskind quarks and of Wilson quarks on 6 x 12 3 lattices in order to study the crossover from the low temperature hadronic regime to the high temperature regime. We investigate the properties of the objects whose exchange gives static screening lengths by reconstructing their correlated quark-antiquark structure. (orig.)
The Skyrmions and quarks in nuclei
International Nuclear Information System (INIS)
Rho, M.
1984-08-01
It is proposed that the quark-bag description and the Skyrmion description of baryons are related to each other by quantized parameters. Topology (through a chiral anomaly) plays an important role in bridging the fundamental theory of the strong interactions (QCD) to effective theories. Some consequences on the efforts to see quark degrees of freedom in nuclear matter are discussed. It is suggested that at low energies there will be no ''smoking gun'' evidences for quark presence in nuclei
The proton's spin: A quark model perspective
International Nuclear Information System (INIS)
Close, F.E.
1989-01-01
Magnetic moments and g A /g V provide information on the correlations among quark spins and flavors in the proton. I compare this information with the deep inelastic polarized data from EMC which has been claimed to show that very little of the proton's spin is due to the quarks. The possibility that there is significant polarization of strange quarks within protons is discussed. 38 refs
A single quark effective potential model
International Nuclear Information System (INIS)
Bodmann, B.E.J.; Vasconcellos, C.A.Z.
1994-01-01
In the present work we construct a radial spherical symmetric single quark potential model for the nucleon, consistent with asymptotic freedom and confinement. The quark mass enters as potential parameter and that way induces indirectly an isospin dependence in the interaction. As a consequence, a contribution to the negative charge square radius of the neutron arises an an effect of the quark core, which simulates an isospin symmetry breaking effect in the nucleon due to strong interaction. (author)
Test of quark fragmentation in the quark-parton model framework
International Nuclear Information System (INIS)
Derrick, M.; Barish, S.J.; Barnes, V.E.
1979-08-01
The hadronic system produced in charged-current antineutrino interactions is used to study fragmentation of the d-quark. Some problems encountered in separating the current quark-fragments are discussed. The fragmentation function for the current quark is in good agreement with the expectations of the naive quark-parton model and, in particular, there is no evidence of either a Q 2 - or x/sub BJ/-dependence. 10 references
Measurement of the Production Rate of Charm Quark Pairs from Gluons in Hadronic $Z^{0}$ Decays
Abbiendi, G; Alexander, Gideon; Allison, J; Anderson, K J; Anderson, S; Arcelli, S; Asai, S; Ashby, S F; Axen, D A; Azuelos, Georges; Ball, A H; Barberio, E; Barlow, R J; Batley, J Richard; Baumann, S; Bechtluft, J; Behnke, T; Bell, K W; Bella, G; Bellerive, A; Bentvelsen, Stanislaus Cornelius Maria; Bethke, Siegfried; Betts, S; Biebel, O; Biguzzi, A; Bloodworth, Ian J; Bock, P; Böhme, J; Boeriu, O; Bonacorsi, D; Boutemeur, M; Braibant, S; Bright-Thomas, P G; Brigliadori, L; Brown, R M; Burckhart, Helfried J; Capiluppi, P; Carnegie, R K; Carter, A A; Carter, J R; Chang, C Y; Charlton, D G; Chrisman, D; Ciocca, C; Clarke, P E L; Clay, E; Cohen, I; Conboy, J E; Cooke, O C; Couchman, J; Couyoumtzelis, C; Coxe, R L; Cuffiani, M; Dado, S; Dallavalle, G M; Dallison, S; Davis, R; De Jong, S; de Roeck, A; Dervan, P J; Desch, Klaus; Dienes, B; Dixit, M S; Donkers, M; Dubbert, J; Duchovni, E; Duckeck, G; Duerdoth, I P; Estabrooks, P G; Etzion, E; Fabbri, Franco Luigi; Fanfani, A; Fanti, M; Faust, A A; Feld, L; Ferrari, P; Fiedler, F; Fierro, M; Fleck, I; Frey, A; Fürtjes, A; Futyan, D I; Gagnon, P; Gary, J W; Gaycken, G; Geich-Gimbel, C; Giacomelli, G; Giacomelli, P; Gibson, W R; Gingrich, D M; Glenzinski, D A; Goldberg, J; Gorn, W; Grandi, C; Graham, K; Gross, E; Grunhaus, Jacob; Gruwé, M; Hajdu, C; Hanson, G G; Hansroul, M; Hapke, M; Harder, K; Harel, A; Hargrove, C K; Harin-Dirac, M; Hauschild, M; Hawkes, C M; Hawkings, R; Hemingway, Richard J; Herten, G; Heuer, R D; Hildreth, M D; Hill, J C; Hobson, P R; Höcker, Andreas; Hoffman, K; Homer, R James; Honma, A K; Horváth, D; Hossain, K R; Howard, R; Hüntemeyer, P; Igo-Kemenes, P; Imrie, D C; Ishii, K; Jacob, F R; Jawahery, A; Jeremie, H; Jimack, Martin Paul; Jones, C R; Jovanovic, P; Junk, T R; Kanaya, N; Kanzaki, J I; Karlen, D A; Kartvelishvili, V G; Kawagoe, K; Kawamoto, T; Kayal, P I; Keeler, Richard K; Kellogg, R G; Kennedy, B W; Kim, D H; Klier, A; Kobayashi, T; Kobel, M; Kokott, T P; Kolrep, M; Komamiya, S; Kowalewski, R V; Kress, T; Krieger, P; Von Krogh, J; Kühl, T; Kyberd, P; Lafferty, G D; Landsman, Hagar Yaël; Lanske, D; Lauber, J; Lawson, I; Layter, J G; Lellouch, Daniel; Letts, J; Levinson, L; Liebisch, R; Lillich, J; List, B; Littlewood, C; Lloyd, A W; Lloyd, S L; Loebinger, F K; Long, G D; Losty, Michael J; Lü, J; Ludwig, J; Liu, D; Macchiolo, A; MacPherson, A L; Mader, W F; Mannelli, M; Marcellini, S; Marchant, T E; Martin, A J; Martin, J P; Martínez, G; Mashimo, T; Mättig, P; McDonald, W J; McKenna, J A; McKigney, E A; McMahon, T J; McPherson, R A; Meijers, F; Méndez-Lorenzo, P; Merritt, F S; Mes, H; Meyer, I; Michelini, Aldo; Mihara, S; Mikenberg, G; Miller, D J; Mohr, W; Montanari, A; Mori, T; Nagai, K; Nakamura, I; Neal, H A; Nisius, R; O'Neale, S W; Oakham, F G; Odorici, F; Ögren, H O; Okpara, A N; Oreglia, M J; Orito, S; Pásztor, G; Pater, J R; Patrick, G N; Patt, J; Pérez-Ochoa, R; Petzold, S; Pfeifenschneider, P; Pilcher, J E; Pinfold, James L; Plane, D E; Poffenberger, P R; Poli, B; Polok, J; Przybycien, M B; Quadt, A; Rembser, C; Rick, Hartmut; Robertson, S; Robins, S A; Rodning, N L; Roney, J M; Rosati, S; Roscoe, K; Rossi, A M; Rozen, Y; Runge, K; Runólfsson, O; Rust, D R; Sachs, K; Saeki, T; Sahr, O; Sang, W M; Sarkisyan-Grinbaum, E; Sbarra, C; Schaile, A D; Schaile, O; Scharff-Hansen, P; Schieck, J; Schmitt, S; Schöning, A; Schröder, M; Schumacher, M; Schwick, C; Scott, W G; Seuster, R; Shears, T G; Shen, B C; Shepherd-Themistocleous, C H; Sherwood, P; Siroli, G P; Skuja, A; Smith, A M; Snow, G A; Sobie, Randall J; Söldner-Rembold, S; Spagnolo, S; Sproston, M; Stahl, A; Stephens, K; Stoll, K; Strom, D; Ströhmer, R; Surrow, B; Talbot, S D; Taras, P; Tarem, S; Teuscher, R; Thiergen, M; Thomas, J; Thomson, M A; Torrence, E; Towers, S; Trefzger, T M; Trigger, I; Trócsányi, Z L; Tsur, E; Turner-Watson, M F; Ueda, I; Van Kooten, R; Vannerem, P; Verzocchi, M; Voss, H; Wäckerle, F; Wagner, A; Waller, D; Ward, C P; Ward, D R; Watkins, P M; Watson, A T; Watson, N K; Wells, P S; Wermes, N; Wetterling, D; White, J S; Wilson, G W; Wilson, J A; Wyatt, T R; Yamashita, S; Zacek, V; Zer-Zion, D
2000-01-01
The rate of secondary charm-quark-pair production has been measured in 4.4 million hadronic Z0 decays collected by OPAL. By selecting events with three jets and tagging charmed hadrons in the gluon jet candidate using leptons and charged D* mesons, the average number of secondary charm-quark pairs per hadronic event is found to be (3.20+-0.21+-0.38)x10-2.
Nonperturbative QCD simulations with 2+1 flavors of improved staggered quarks
International Nuclear Information System (INIS)
Bazavov, A.; Toussaint, D.; Bernard, C.; Laiho, J.; DeTar, C.; Levkova, L.; Oktay, M. B.; Gottlieb, Steven; Heller, U. M.; Hetrick, J. E.; Mackenzie, P. B.; Sugar, R.; Van de Water, R. S.
2010-01-01
Dramatic progress has been made over the last decade in the numerical study of quantum chromodynamics (QCD) through the use of improved formulations of QCD on the lattice (improved actions), the development of new algorithms, and the rapid increase in computing power available to lattice gauge theorists. In this article simulations of full QCD are described using the improved staggered quark formalism, ''asqtad'' fermions. These simulations were carried out with two degenerate flavors of light quarks (up and down) and with one heavier flavor, the strange quark. Several light quark masses, down to about three times the physical light quark mass, and six lattice spacings have been used. These enable controlled continuum and chiral extrapolations of many low energy QCD observables. The improved staggered formalism is reviewed, emphasizing both advantages and drawbacks. In particular, the procedure for removing unwanted staggered species in the continuum limit is reviewed. Then the asqtad lattice ensembles created by the MILC Collaboration are described. All MILC lattice ensembles are publicly available, and they have been used extensively by a number of lattice gauge theory groups. The physics results obtained with them are reviewed, and the impact of these results on phenomenology is discussed. Topics include the heavy quark potential, spectrum of light hadrons, quark masses, decay constants of light and heavy-light pseudoscalar mesons, semileptonic form factors, nucleon structure, scattering lengths, and more.
Single top quark production with CMS
Directory of Open Access Journals (Sweden)
Piccolo Davide
2013-11-01
Full Text Available Measurements of single top quark production performed using the CMS experiment [1] data collected in 2011 at centre-of-mass energies of 7 TeV and in 2012 at 8 TeV, are presented. The cross sections for the electroweak production of single top quarks in the t-channel and in association with W-bosons is measured and the results are used to place constraints on the CKM matrix element Vtb. Measurements of top quark properties in single top quark production are also presented. The results include the measurement of the charge ratio in the single top t-channel.
The quark model and asymptotic freedom
International Nuclear Information System (INIS)
Anon.
1986-01-01
The authors stress that it is not their task to provide a detailed account of the quark model (this is given in many monographs and reviews). This chapter is merely a prolog to the complex contemporary problems of high-energy physics which form the main subject of the present monograph. The quark model is based on the idea that there exist hypothetical fundamental particles - quarks, which they shall denote by q-bar/sub i/ (the index i characterizes the type of quark). From these particles and their antiparticles one constructs bound states, which are identified with the known hadrons. It turns out that all the observed mesons can be constructed from a quark q/sub i/ and an antiquark q-bar/sub i/, while the baryons (antibaryons) can be constructed from three quarks (antiquarks). To make it possible to build up all the observed hadrons and their characteristics, the authors must postulate that the quarks (antiquarks) possess the following properties: 1) spin 1/2; 2) isospin. It is necessary to introduce isospin 1/2 for the construction of the nonstrange hadrons. It has been proposed to denote the quark with isospin projection tau/sub 3/ = 1/2 by the symbol u (from the English ''up'') and the quark with isospin projection tau/sub 3/ = -1/2 by the symbol d (from the English ''down'')
CP Violation in Single Top Quark Production
Energy Technology Data Exchange (ETDEWEB)
Geng, Weigang [Michigan State Univ., East Lansing, MI (United States)
2012-01-01
We present a search for CP violation in single top quark production with the DØ experiment at the Tevatron proton-antiproton collider. CP violation in the top electroweak interaction results in different single top quark production cross sections for top and antitop quarks. We perform the search in the single top quark final state using 5.4 fb^{-1} of data, in the s-channel, t-channel, and for both combined. At this time, we do not see an observable CP asymmetry.
Quark Physics without Quarks: A Review of Recent Developments in S-Matrix Theory.
Capra, Fritjof
1979-01-01
Reviews the developments in S-matrix theory over the past five years which have made it possible to derive results characteristic of quark models without any need to postulate the existence of physical quarks. In the new approach, the quark patterns emerge as a consequence of combining the general S-matrix principles with the concept of order.…
Non-diagonal processes of singlet and ordinary quark production
International Nuclear Information System (INIS)
Bejlin, V.A.; Vereshkov, G.M.; Kuksa, V.I.
1995-01-01
Non-diagonal processes of singlet and ordinary quark production are analyzed in the model where the down singlet quark mixes with the ordinary ones. The possibility of experimental selection of h-quark effects is demonstrated
A higher twist correction to heavy quark production
International Nuclear Information System (INIS)
Brodsky, S.J.; Gunion, J.F.; Soper, D.E.
1987-06-01
The leading twist prediction for heavy quark production and a model for a higher twist correction that may be important for charm production was discussed. The correction arises from the interaction of the charm quark with spectator quarks
The charge form factor of pseudoscalar mesons in a relativistic constituent quark model
Energy Technology Data Exchange (ETDEWEB)
Cardarelli, F.; Pace, E. [Univ. of Rome, Roma (Italy); Grach, I.L. [Inst. of Theoretical and Experimental Physics, Moscow (Russian Federation)] [and others
1994-04-01
The charge form factor of pseudoscalar mesons has been investigated in the light-cone formalism, up to Q{sup 2} relevant to CEBAF energies. The consequences of adopting the meson wave functions generated through the Godfrey-Isgur q{bar q} potential, which reproduces the mass spectra, are discussed.
Superconvergent gluon propagator and the quark-antiquark potential
International Nuclear Information System (INIS)
Oehme, R.; Chicago Univ., IL; Chicago Univ., IL
1989-01-01
Superconvergence of the gluon propagator, together with the asymptotically negative sign of the discontinuity, imply that the structure function has a representation which corresponds to an approximately linear quark-antiquark potential, provided the number of flavors is less than ten. For more than ten flavors, there is no indication for a linear potential within this framework. The connection with metric confinement is emphasized. Possible dipole terms are considered briefly. (orig.)
Quark mean field theory and consistency with nuclear matter
International Nuclear Information System (INIS)
Dey, J.; Tomio, L.; Dey, M.; Frederico, T.
1989-01-01
1/N c expansion in QCD (with N c the number of colours) suggests using a potential from meson sector (e.g. Richardson) for baryons. For light quarks a σ field has to be introduced to ensure chiral symmetry breaking ( χ SB). It is found that nuclear matter properties can be used to pin down the χ SB-modelling. All masses, M Ν , m σ , m ω are found to scale with density. The equations are solved self consistently. (author)
Estimates for the parameters of the heavy quark expansion
Energy Technology Data Exchange (ETDEWEB)
Heinonen, Johannes; Mannel, Thomas [Universitaet Siegen (Germany)
2015-07-01
We give improved estimates for the non-perturbative parameters appearing in the heavy quark expansion for inclusive decays. While the parameters appearing in low orders of this expansion can be extracted from data, the number of parameters in higher orders proliferates strongly, making a determination of these parameters from data impossible. Thus, one has to rely on theoretical estimates which may be obtained from an insertion of intermediate states. We refine this method and attempt to estimate the uncertainties of this approach.