Quark Models and Quark Phenomenology
Lipkin, Harry Jeannot
1997-01-01
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. A model of colored quarks interacting with a one-gluon-exchange potential explained the systematics of the meson and baryon spectrum and gave a hadron mass formula in surprising agreement with experiment. The simple quark model dismissed as heresy and witchcraft by the establishment predicted quantum numbers of an enormous number of hadronic states as well as relations between masses, reaction cross sections and electromagnetic properties, all unexplained by other approaches. Further developments leading to QCD included confinement in the large $N_c$ limit, duality, dual resonance and string models, high energy scattering systematics, unified treatment of mesons and baryons, no exotics and no free quarks.
Quark confinement in a constituent quark model
Energy Technology Data Exchange (ETDEWEB)
Langfeld, K.; Rho, M. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Service de Physique Theorique
1995-07-01
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.
Indian Academy of Sciences (India)
H Weigel
2003-11-01
In this talk I review studies of hadron properties in bosonized chiral quark models for the quark ﬂavor dynamics. Mesons are constructed from Bethe–Salpeter equations and baryons emerge as chiral solitons. Such models require regularization and I show that the two-fold Pauli–Villars regularization scheme not only fully regularizes the effective action but also leads the scaling laws for structure functions. For the nucleon structure functions the present approach serves to determine the regularization prescription for structure functions whose leading moments are not given by matrix elements of local operators. Some numerical results are presented for the spin structure functions.
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)
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)
Institute of Scientific and Technical Information of China (English)
ZONG Hong-Shi; WU Xiao-Hua; SUN Wei-Min; ZHAO En-Guang; WANG Fan
2003-01-01
A method for obtaining the smallcurrent quark mass dependence of the dressed quark propagator froman effective quark-quark interaction model is developed. Within this approach the small current quark mass effects ondressed-quark propagator have been studied. A comparison with previous results is given.
Santopinto, E
2015-01-01
In this contribution, we briefly discuss the results for charmonium and bottomonium spectra with self-energy corrections in the unquenched quark model, due to the coupling to the meson-meson continuum. The UQM formalism can be extended to include also the effects of hybrid mesons, i.e. hybrid loops. Finally, we discuss the results of a calculation of hybrid mesons spectrum in Coulomb Gauge QCD.
Recursive fragmentation model with quark spin. Application to quark polarimetry
Artru, X
2010-01-01
An elementary recursive model accounting for the quark spin in the fragmentation of a quark into mesons is presented. The quark spin degree of freedom is represented by a two-components spinor. Spin one meson can be included. The model produces Collins effect and jet handedness. The influence of the initial quark polarisation decays exponentially with the rank of the meson, at dierent rates for longitudinal and transverse polarisations
Quark Model and multiquark system
da Silva, Cristiane Oldoni
2010-01-01
The discovery of many particles, especially in the 50's, when the firsts accelerators appeared, caused the searching for a model that would describe in a simple form the whole of known particles. The Quark Model, based in the mathematical structures of group theory, provided in the beginning of the 60's a simplified description of hadronic matter already known, proposing that three particles, called quarks, would originate all the observed hadrons. This model was able to preview the existence of particles that were later detected, confirming its consistency. Extensions of the Quark Model were made in the beginning of the 70's, focusing in describing observed particles that were excited states of the fundamental particles and others that presented new quantum numbers (flavors). Recently, exotic states as tetraquarks and pentaquarks types, also called multiquarks systems, previewed by the model, were observed, what renewed the interest in the way as quarks are confined inside the hadrons. In this article we pre...
Stability of Quark Star Models
Azam, M.; Mardan, S. A.; Rehman, M. A.
2016-05-01
In this paper, we investigate the stability of quark stars with four different types of inner matter configurations; isotropic, charged isotropic, anisotropic and charged anisotropic by using the concept of cracking. For this purpose, we have applied local density perturbations technique to the hydrostatic equilibrium equation as well as on physical parameters involved in the model. We conclude that quark stars become potentially unstable when inner matter configuration is changed and electromagnetic field is applied.
Baryons in the unquenched quark model
Bijker, R; Lopez-Ruiz, M A; Santopinto, E
2016-01-01
In this contribution, we present the unquenched quark model as an extension of the constituent quark model that includes the effects of sea quarks via a $^{3}P_{0}$ quark-antiquark pair-creation mechanism. Particular attention is paid to the spin and flavor content of the proton, magnetic moments and $\\beta$ decays of octet baryons.
Pallante, E.; Petronzio, R.
1995-01-01
We construct an effective Lagrangian for low energy hadronic interactions through an infinite expansion in inverse powers of the low energy cutoff Î›Ï‡ of all possible chiral invariant non-renormalizable interactions between quarks and mesons degrees of freedom arising from the bosonization of a gen
Strange quark matter and quark stars with the Dyson-Schwinger quark model
Chen, H.; Wei, J.-B.; Schulze, H.-J.
2016-09-01
We calculate the equation of state of strange quark matter and the interior structure of strange quark stars in a Dyson-Schwinger quark model within rainbow or Ball-Chiu vertex approximation. We emphasize constraints on the parameter space of the model due to stability conditions of ordinary nuclear matter. Respecting these constraints, we find that the maximum mass of strange quark stars is about 1.9 solar masses, and typical radii are 9-11km. We obtain an energy release as large as 3.6 × 10^{53} erg from conversion of neutron stars into strange quark stars.
Strange quark matter and quark stars with the Dyson-Schwinger quark model
Chen, H; Schulze, H -J
2016-01-01
We calculate the equation of state of strange quark matter and the interior structure of strange quark stars in a Dyson-Schwinger quark model within rainbow or Ball-Chiu vertex approximation. We emphasize constraints on the parameter space of the model due to stability conditions of ordinary nuclear matter. Respecting these constraints, we find that the maximum mass of strange quark stars is about 1.9 solar masses, and typical radii are 9--11 km. We obtain an energy release as large as $3.6 \\times 10^{53}\\,\\text{erg}$ from conversion of neutron stars into strange quark stars.
Strange quark matter and quark stars with the Dyson-Schwinger quark model
Energy Technology Data Exchange (ETDEWEB)
Chen, H.; Wei, J.B. [China University of Geosciences, School of Mathematics and Physics, Wuhan (China); Schulze, H.J. [Universita di Catania, Dipartimento di Fisica, Catania (Italy); INFN, Sezione di Catania (Italy)
2016-09-15
We calculate the equation of state of strange quark matter and the interior structure of strange quark stars in a Dyson-Schwinger quark model within rainbow or Ball-Chiu vertex approximation. We emphasize constraints on the parameter space of the model due to stability conditions of ordinary nuclear matter. Respecting these constraints, we find that the maximum mass of strange quark stars is about 1.9 solar masses, and typical radii are 9-11 km. We obtain an energy release as large as 3.6 x 10{sup 53} erg from conversion of neutron stars into strange quark stars. (orig.)
NN Interaction in Chiral Constituent Quark Models
Valcarce, A; González, P
2003-01-01
We review the actual state in the description of the NN interaction by means of chiral constituent quark models. We present a series of relevant features that are nicely explained within the quark model framework.
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)
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)
Mesons in the Constituent Quark Model
Institute of Scientific and Technical Information of China (English)
WANG Li; PING Jia-Lun
2007-01-01
The quark-antiquark (q(-q)) spectrum is studied by solving the Schrǒdinger equation in the framework of non-relativistic constituent quark model. An overall good fit to the experimental data of meson is obtained. The interactions between quark and antiquark consist of quadratic colour confinement-exchange, one-gluon-exchange, and Goldstone-boson-exchange potentials.
Wang, X J; Wang, Xiao-Jun; Yan, Mu-Lin
1999-01-01
We study SU(3)$_L\\timesSU(3)_R$ chiral quark model of mesons up to next leading order of $1/N_c$ expansion. Composite vector and axial-vector mesons resonances are introduced via non-linear realization of chiral SU(3) and vector meson dominant. Effects of one-loop graphs of pseudoscalar, vector and axial-vector mesons is calculated systematically and the significant results are obtained. Correction of effective gluon interaction is studied too. The light quark masses are introduced via new mechanism which agree with phenomenology and the requirement of chiral symmetry. Up to powers four of derivatives, chiral effective lagrangian of mesons is derived and evaluated to next leading order of $1/N_c$. Low energy limit of the model is examined. Ten low energy coupling constants $L_i(i=1,2,...,10)$ in ChPT are obtained and agree with ChPT well.
Gell-Mann, M.
In these lectures I want to speak about at least two interpretations of the concept of quarks for hadrons and the possible relations between them. First I want to talk about quarks as "constituent quarks". These were used especially by G. Zweig (1964) who referred to them as aces. One has a sort of a simple model by which one gets elementary results about the low-lying bound and resonant states of mesons and baryons, and certain crude symmetry properties of these states, by saying that the hadrons act as if they were made up of subunits, the constituent quarks q. These quarks are arranged in an isotopic spin doublet u, d and an isotopic spin singlet s, which has the same charge as d and acts as if it had a slightly higher mass…
Xu, J L
2002-01-01
We assume that the u quarks and the d quarks constitute a body center cubic quark lattice in the vacuum. Using energy band theory, we deduce an excited quark spectrum (from the quark lattice). Using the accompanying excitation concept, we deduce a baryon spectrum (including S, C, b, I, Q, and mass) from the quark spectrum. With a phenomenological binding energy formula, we deduce a meson spectrum (including S, C, b, I, Q, and mass) from the quark spectrum. The baryon and meson spectra agree well with experimental results. The BCC Quark Model predicts many new quarks (u'(3), d'(6)), baryons ($\\Lambda^0(4280)$, $\\Lambda_{C}^{+}(6600)$, $\\Lambda_{b}^{0}(9960))$, and mesons (K(3597), D(5996), B(9504), $\\eta(5926)$, $\\Upsilon(17805)$, T(1603) with I=2). The quarks u'(3) and d'(6) and the meson T(1603) have already been discovered.
Nuclear Structure Functions from Constituent Quark Model
Arash, F; Arash, Firooz; Atashbar-Tehrani, Shahin
1999-01-01
We have used the notion of the constituent quark model of nucleon, where a constituent quark carries its own internal structure, and applied it to determine nuclear structure functions ratios. It is found that the description of experimental data require the inclusion of strong shadowing effect for $x<0.01$. Using the idea of vector meson dominance model and other ingredients this effect is calculated in the context of the constituent quark model. It is rather striking that the constituent quark model, used here, gives a good account of the data for a wide range of atomic mass number from A=4 to A=204.
Composite Models of Quarks and Leptons.
Geng, Chaoqiang
1987-09-01
We review the various constraints on composite models of quarks and leptons. Some dynamical mechanisms for chiral symmetry breaking in chiral preon models are discussed. We have constructed several "realistic candidate" chiral preon models satisfying complementarity between the Higgs and confining phases. The models predict three to four generations of ordinary quarks and leptons.
Radiatively induced quark and lepton mass model
Nomura, Takaaki; Okada, Hiroshi
2016-10-01
We propose a radiatively induced quark and lepton mass model in the first and second generation with extra U (1) gauge symmetry and vector-like fermions. Then we analyze the allowed regions which simultaneously satisfy the FCNCs for the quark sector, LFVs including μ- e conversion, the quark mass and mixing, and the lepton mass and mixing. Also we estimate the typical value for the (g - 2) μ in our model.
An Extended Chiral SU(3) Quark Model
Institute of Scientific and Technical Information of China (English)
ZHANG Zong-Ye; YU You-Wen; WANG Ping; DAI Lian-Rong
2003-01-01
The chiral SU(3) quark model is extended by including the vector meson exchanges to describe the short range interactions. The phase shifts of NN scattering are studied in this model. Compared with the results of the chiral SU(3) quark model in which only the pseudo-scalar and scalar chiralfields are considered, the phase shifts of 1 So wave are obviously improved.
A New Model for Quark Mass Matrix
Institute of Scientific and Technical Information of China (English)
JIANG Zhi-Wei
2011-01-01
We study the status of S3, I.e. A slightly broken symmetry of quarks and propose a new model in which the S3 symmetry among the three generation up-quarks is slightly broken into the C2 symmetry while the S3 symmetry of the down-quarks is completely broken in a different way.%@@ We study the status of Sa, i.e.a slightly broken symmetry of quarks and propose a new model in which the Sa symmetry among the three generation up-quarks is slightly broken into the C symmetry while the S symmetry of the down-quarks is completely broken in a different way.
The Body Center Cubic Quark Lattice Model
Lin Xu, Jiao
2004-01-01
The Standard Model while successful in many ways is incomplete; many questions remain. The origin of quark masses and hadronization of quarks are awaiting an answer. From the Dirac sea concept, we infer that two kinds of elementary quarks (u(0) and d(0)) constitute a body center cubic (BCC) quark lattice with a lattice constant a < $10^{-18}$m in the vacuum. Using energy band theory and the BCC quark lattice, we can deduce the rest masses and the intrinsic quantum numbers (I, S, C, b and Q) of quarks. With the quark spectrum, we deduce a baryon spectrum. The theoretical spectrum is in agreement well with the experimental results. Not only will this paper provide a physical basis for the Quark Model, but also it will open a door to study the more fundamental nature at distance scales <$10^{-18}$m. This paper predicts some new quarks $u_{c}$(6490) and d$_{b}$(9950), and new baryons $\\Lambda_{c}^{+}$(6500), $\\Lambda_{b}^{0}$(9960).
Explicit and Dynamical Chiral Symmetry Bresking in an Effective Quark-Quark Interaction Model
Institute of Scientific and Technical Information of China (English)
宗红石; 吴小华; 侯丰尧; 赵恩广
2004-01-01
A method for obtaining the small current quark mass effect on the dressed quark propagator from an effective quark-quark interaction model is developed. Within this approach both the explicit and dynamical chiral symmetry breakings are analysed. A comparison with the previous results is given.
Quark Model in the Quantum Mechanics Curriculum.
Hussar, P. E.; And Others
1980-01-01
This article discusses in detail the totally symmetric three-quark karyonic wave functions. The two-body mesonic states are also discussed. A brief review of the experimental efforts to identify the quark model multiplets is given. (Author/SK)
Quark Model in the Quantum Mechanics Curriculum.
Hussar, P. E.; And Others
1980-01-01
This article discusses in detail the totally symmetric three-quark karyonic wave functions. The two-body mesonic states are also discussed. A brief review of the experimental efforts to identify the quark model multiplets is given. (Author/SK)
Senju, H.
1991-07-01
Inspired by unique features of the preon-subpreon model, we propose a new scheme for quark mixing. In our scheme, the mass relations m_{d} << m_{s} << m_{b} and m_{u} << m_{c} << m_{t} are naturally understood. The resultant CKM matrix has very nice properties. The fact that |V_{us}| and |V_{cd}| are remarkably large compared with other off-diagonal elements is naturally understood. |V_{cb}| =~ |V_{ts}| is predicted and their small values are explained. |V_{ub}| and |V_{td}| are predicted to be much smaller than |V_{cb}|. The parametrization invariant measure of CP violation, J, is predicted to be |V_{ud}| |V_{ub}| |V_{td}| sin phi. The mass relations and mixings of q', q'', l_{s} and leptons are also discussed.
Duality between quark-quark and quark-antiquark pairing in 1+1 dimensional large N models
Thies, M
2003-01-01
We identify a canonical transformation which maps the chiral Gross-Neveu model onto a recently proposed Cooper pair model. Baryon number and axial charge are interchanged. The same physics can be described either as chiral symmetry breaking (quark-antiquark pairing) or as superconductivity (quark-quark pairing).
Strangeness suppression in the unquenched quark model
Bijker, Roelof; Santopinto, Elena
2016-01-01
In this contribution, we discuss the strangeness suppression in the proton in the framework of the unquenched quark model. The theoretical results are in good agreement with the values extracted from CERN and JLab experiments.
The Meson Spectrum of the BCC Quark Model (A Modification of the Quark Model)
Xu, J L; Xu, Jiao Lin; Yu, Xin
2002-01-01
Using the quark spectrum of the BCC Quark Model [1] and the phenomenological formula for the binding energies of the mesons, not only have we deduced the intrinsic quantum numbers (I, S, C, b, and Q) of all mesons as was done with the Quark Model [2], but also we deduced the meson mass spectrum in agreement with experimental results [3] that we could not deduce using the Quark Model. The experimental meson spectrum gives some evidence of the existence of the new quarks $q_S^*(1391)$, $q_S^*(2551)$ and $q_C^*(6591)$..., which are predicted by the BCC Quark Model. The meson $\\chi (1600)$ $[2^+(2^{++})]$ with I = 2 (predicted by the BCC Quark Model--T(1603)) has already been discovered [4]. If this is finally confirmed, it will provide a strong support for the BCC Quark Model. We propose a search for the mesons D(5996), $D_S (6151)$, B(9504), $B_S (9659)$, $B_C (11031)$, $\\eta (5926)$, $\\eta (17837)$, $\\psi (25596)$, $\\Upsilon (17805)$, $\\Upsilon (29597)$, T(960), T(1282), T(1603), and T(1924).
The Physical Foundation of the Quark Model the Quark Model as an approximation of the BCC Model
Xu, J L
2001-01-01
From the Dirac sea concept, the BCC model infers that the quarks u and d constitute a body center cubic quark lattice in the vacuum; when a quark $q^*$ is excited from the vacuum, the nearest primitive cell u' and d' is accompanying excited by the quark $q^*$. Using the energy band theory, the model deduces the quantum numbers (I, S, C, b, and Q) and the masses of all quarks using a united mass formula. Then, it shows that the system of} 3 excited quarks ($q^*u'd'
Decaying hadrons within constituent-quark models
Kleinhappel, Regina
2012-01-01
Within conventional constituent-quark models hadrons come out as stable bound states of the valence (anti)quarks. Thereby the resonance character of hadronic excitations is completely ignored. A more realistic description of hadron spectra can be achieved by including explicit mesonic degrees of freedom, which couple directly to the constituent quarks. We will present a coupled-channel formalism that describes such hybrid systems in a relativistically invariant way and allows for the decay of excited hadrons. The formalism is based on the point-form of relativistic quantum mechanics. If the confining forces between the (anti)quarks are described by instantaneous interactions it can be formally shown that the mass-eigenvalue problem for a system that consists of dynamical (anti)quarks and mesons reduces to a hadronic eigenvalue problem in which the eigenstates of the pure confinement problem (bare hadrons) are coupled via meson loops. The only point where the quark substructure enters are form factors at the m...
Extended Quark Potential Model From Random Phase Approximation
Institute of Scientific and Technical Information of China (English)
DENGWei－Zhen; CHENXiao－Lin; 等
2002-01-01
The quark potential model is extended to include the sea quark excitation using the random phase approximation.The effective quark interaction preserves the important QCD properties-chiral symmetry and confinement simultaneously.A primary qualitative analysis shows that the π meson as a well-known typical Goldstone boson and the other mesons made up of valence qq quark pair such as the ρ meson can also be described in this extended quark potential model.
QQqq Four-Quark Bound States in Chiral SU(3) Quark Model
Institute of Scientific and Technical Information of China (English)
ZHANG Ming; ZHANG Hai-Xia; ZHANG Zong-Ye
2008-01-01
The possibility of QQqq heavy-light four-quark bound states has been analyzed by means of the chiral SU(3) quark model, where Q is the heavy quark (c or b) and q is the light quark (u, d, or s). We obtain a bound state for the bbnn configuration with quantum number JP=1+, I=0 and for the ccnn (JP=1+, I=0) configuration, which is not bound but slightly above the D*D* threshold (n is u or d quark). Meanwhile, we also conclude that a weakly bound state in bbnn system can also be found without considering the chiral quark interactions between the two light quarks, yet its binding energy is weaker than that with the chiral quark interactions.
Heavy Baryons in a Quark Model
Energy Technology Data Exchange (ETDEWEB)
Winston Roberts; Muslema Pervin
2007-11-14
A quark model is applied to the spectrum of baryons containing heavy quarks. The model gives masses for the known heavy baryons that are in agreement with experiment, but for the doubly-charmed baryon $\\Xi_{cc}$, the model prediction is too heavy. Mixing between the $\\Xi_Q$ and $\\Xi_Q^\\prime$ states is examined and is found to be small for the lowest lying states. In contrast with this, mixing between the $\\Xi_{bc}$ and $\\Xi_{bc}^\\prime$ states is found to be large, and the implication of this mixing for properties of these states is briefly discussed. We also examine heavy-quark spin-symmetry multiplets, and find that many states in the model can be placed in such multiplets.
The NJL Model for Quark Fragmentation Functions
Energy Technology Data Exchange (ETDEWEB)
T. Ito, W. Bentz, I. Cloet, A W Thomas, K. Yazaki
2009-10-01
A description of fragmentation functions which satisfy the momentum and isospin sum rules is presented in an effective quark theory. Concentrating on the pion fragmentation function, we first explain the reason why the elementary (lowest order) fragmentation process q → qπ is completely inadequate to describe the empirical data, although the “crossed” process π → qq describes the quark distribution functions in the pion reasonably well. Then, taking into account cascade-like processes in a modified jet-model approach, we show that the momentum and isospin sum rules can be satisfied naturally without introducing any ad-hoc parameters. We present numerical results for the Nambu-Jona-Lasinio model in the invariant mass regularization scheme, and compare the results with the empirical parametrizations. We argue that this NJL-jet model provides a very useful framework to calculate the fragmentation functions in an effective chiral quark theory.
The NJL Model for Quark Fragmentation Functions
Energy Technology Data Exchange (ETDEWEB)
T. Ito, W. Bentz, I. Cloet, A W Thomas, K. Yazaki
2009-10-01
A description of fragmentation functions which satisfy the momentum and isospin sum rules is presented in an effective quark theory. Concentrating on the pion fragmentation function, we first explain the reason why the elementary (lowest order) fragmentation process q → qπ is completely inadequate to describe the empirical data, although the “crossed” process π → qq describes the quark distribution functions in the pion reasonably well. Then, taking into account cascade-like processes in a modified jet-model approach, we show that the momentum and isospin sum rules can be satisfied naturally without introducing any ad-hoc parameters. We present numerical results for the Nambu-Jona-Lasinio model in the invariant mass regularization scheme, and compare the results with the empirical parametrizations. We argue that this NJL-jet model provides a very useful framework to calculate the fragmentation functions in an effective chiral quark theory.
Quark Nova Model for Fast Radio Bursts
Shand, Zachary; Koning, Nico; Ouyed, Rachid
2015-01-01
FRBs are puzzling, millisecond, energetic radio transients with no discernible source; observations show no counterparts in other frequency bands. The birth of a quark star from a parent neutron star experiencing a quark nova - previously thought undetectable when born in isolation - provides a natural explanation for the emission characteristics of FRBs. The generation of unstable r-process elements in the quark nova ejecta provides millisecond exponential injection of electrons into the surrounding strong magnetic field at the parent neutron star's light cylinder via $\\beta$-decay. This radio synchrotron emission has a total duration of hundreds of milliseconds and matches the observed spectrum while reducing the inferred dispersion measure by approximately 200 cm$^{-3}$ pc. The model allows indirect measurement of neutron star magnetic fields and periods in addition to providing astronomical measurements of $\\beta$-decay chains of unstable neutron rich nuclei. Using this model, we can calculate expected FR...
Quark distribution functions in the chiral quark-soliton model cancellation of quantum anomalies
Göke, K; Polyakov, M V; Schweitzer, P; Urbano, D
2001-01-01
In the framework of the chiral quark-soliton model of the nucleon we investigate the properties of the polarized quark distribution. In particular we analyse the so called anomalous difference between the representations of the quark distribution functions in terms of occupied and non-occupied quark states. By an explicit analytical calculation it is shown that this anomaly is absent in the polarized isoscalar distribution \\Delta u + \\Delta d, which is ultaviolet finite. In the case of the polarized isovector quark distribution which is also needed for the regularization of the ultraviolet divergence.
Quark model and high energy collisions
Anisovich, V V; Nyíri, J; Shabelski, Yu M
2004-01-01
This is an updated version of the book published in 1985. QCD-motivated, it gives a detailed description of hadron structure and soft interactions in the additive quark model, where hadrons are regarded as composite systems of dressed quarks. In the past decade it has become clear that nonperturbative QCD, responsible for soft hadronic processes, may differ rather drastically from perturbative QCD. The understanding of nonperturbative QCD requires a detailed investigation of the experiments and the theoretical approaches. Bearing this in mind, the book has been rewritten paying special attenti
Moreno Llacer, Maria; The ATLAS collaboration
2016-01-01
Production of top quark pairs in association with heavy Standard Model bosons or with heavy flavour quark-pairs is important both as a signal and a background in several ATLAS analyses. Strong constraints on such processes cannot at present be obtained from data, and therefore their modeling by Monte Carlo simulation as well as the associated uncertainties are important. This poster documents the Monte Carlo samples currently being used in ATLAS for the ttH and ttV (V=W,Z vector bosons) and tt+bottom and charm quark pairs processes for sqrt(s)=13 TeV proton-proton collisions.
Extended Quark Potential Model from Random Phase Approximation
Institute of Scientific and Technical Information of China (English)
DENG Wei-Zhen; CHEN Xiao-Lin; LU Da-Hai; YANG Li-Ming
2002-01-01
The quark potential model is extended to include the sea quark excitation using the random phase approx-imation. The effective quark interaction preserves the important QCD properties - chiral symmetry and confinementsimultaneously. A primary qualitative analysis shows that the π meson as a well-known typical Goldstone boson andthe other mesons made up of valence qq quark pair such as the ρ meson can also be described in this extended quarkpotential model.
A model of quark and lepton mixing
Energy Technology Data Exchange (ETDEWEB)
King, Stephen F. [School of Physics and Astronomy, University of Southampton,Southampton, SO17 1BJ (United Kingdom)
2014-01-22
We propose a model of quark and lepton mixing based on the tetrahedral A{sub 4} family symmetry with quark-lepton unification via the tetra-colour Pati-Salam gauge group SU(4){sub PS}, together with SU(2){sub L}×U(1){sub R}. The “tetra-model” solves many of the flavour puzzles and remarkably gives ten predictions at leading order, including all six PMNS parameters. The Cabibbo angle is approximately given by θ{sub C}≈1/4, due to the tetra-vacuum alignment (1,4,2), providing the Cabibbo connection between quark and lepton mixing. Higher order corrections are responsible for the smaller quark mixing angles and CP violation and provide corrections to the Cabibbo and lepton mixing angles and phases. The tetra-model involves an SO(10)-like pattern of Dirac and heavy right-handed neutrino masses, with the strong up-type quark mass hierarchy cancelling in the see-saw mechanism, leading to a normal hierarchy of neutrino masses with an atmospheric angle in the first octant, θ{sub 23}{sup l}=40{sup ∘}±1{sup ∘}, a solar angle θ{sub 12}{sup l}=34{sup ∘}±1{sup ∘}, a reactor angle θ{sub 13}{sup l}=9.0{sup ∘}±0.5{sup ∘}, depending on the ratio of neutrino masses m{sub 2}/m{sub 3}, and a Dirac CP violating oscillation phase δ{sup l}=260{sup ∘}±5{sup ∘}.
Meson cloud effects on the pion quark distribution function in the chiral constituent quark model
Watanabe, Akira; Suzuki, Katsuhiko
2016-01-01
We investigate the valence quark distribution function of the pion $v^{\\pi}(x,Q^2)$ in the framework of the chiral constituent quark model and evaluate the meson cloud effects on $v^{\\pi}(x,Q^2)$. We explicitly demonstrate how the meson cloud effects affect $v^{\\pi}(x,Q^2)$ in detail. We find that the meson cloud correction causes an overall 32\\% reduction of the valence quark distribution and an enhancement at the small Bjorken $x$ regime. Besides, we also find that the dressing effect of the meson cloud will make the valence quark distribution to be softer in the large $x$ region.
Heavy Baryon Transitions in a Relativistic Three-Quark Model
Ivanov, M A; Kroll, P; Lyubovitskij, V E
1997-01-01
Exclusive semileptonic decays of bottom and charm baryons are considered within a relativistic three-quark model with a Gaussian shape for the baryon-three-quark vertex and standard quark propagators. We calculate the baryonic Isgur-Wise functions, decay rates and asymmetry parameters.
Flavor content of the nucleon in an unquenched quark model
Bijker, R
2008-01-01
We discuss the flavor content of the nucleon in an unquenched quark model in which the effects of quark-antiquark pairs (up, down and strange) are taken into account in an explicit form. It is shown that the inclusion of quark-antiquark pairs leads to an excess of anti-d over anti-u quarks in the proton and to a large contribution of orbital angular momentum to the spin of the proton.
Statistical Quark Model for the Nucleon Structure Function
Mirez, Carlos; Tomio, Lauro; Trevisan, Luis A.; Frederico, Tobias
2009-06-01
A statistical quark model, with quark energy levels given by a central linear confining potential is used to obtain the light sea-quark asymmetry, d¯/ū, and also for the ratio d/u, inside the nucleon. After adjusting a temperature parameter by the Gottfried sum rule violation, and chemical potentials by the valence up and down quark normalizations, the results are compared with experimental data available.
Chiral quark model with relativistic kinematics
Garcilazo, H
2003-01-01
The non-strange baryon spectrum is studied within a three-body model that incorporates relativistic kinematics. We found that the combined effect of relativistic kinematics together with the pion exchange between quarks is able to reverse the order of the first positive- and negative-parity nucleon excited states as observed experimentally. Including the chiral partner of the pion (the $\\sigma$ meson) leads to an overall good description of the spectrum.
A model of radiatively induced quark and lepton mass model
Nomura, Takaaki
2017-07-01
We discuss a radiatively induced quark and lepton mass model in the rst and second generation introducing extra U(1) gauge symmetry, discrete Z 2 symmetry, vector-like fermions and exotic scalar elds. Then we analyze the allowed parameter regions which simultaneously satisfy the constraints of FCNCs for the quark sector and of LFVs including μ - e conversion, observed quark mass and mixing, and the lepton mass and mixing. In addition, the typical value for the (g - 2) μ in our model is presented. We also show extension of the model in which Majorana type neutrino masses are generated at the two loop level.
Semiclassical projection of hedgehog models with quarks
Energy Technology Data Exchange (ETDEWEB)
Cohen, T.D.; Broniowski, W.
1986-12-01
A simple semiclassical method is presented for calculating physical observables in states with good angular momentum and isospin for models whose mean-field solutions are hedgehogs. The method is applicable for theories which have both quark and meson degrees of freedom. The basic approach is to find slowly rotating solutions to the time-dependent mean-field equations. A nontrivial set of differential equations must be solved to find the quark configuration for these rotating hedgehogs. The parameters which specify the rotating solutions are treated as the collective degrees of freedom. They are requantized by imposing a set of commutation relations which ensures the correct algebra for the SU(2) x SU(2) group of angular momentum and isospin. Collective wave functions can then be found and with these wave functions all matrix elements can be calculated. The method is applied to a simple version of the chiral quark-meson model. A number of physical quantities such as magnetic moments, charge distributions, g/sub A/, g/sub ..pi..//sub N//sub N/, N-..delta.. mass splitting, properties of the N-..delta.. transition, etc., are calculated.
Charmed particle lifetimes. [Review, six quark model
Energy Technology Data Exchange (ETDEWEB)
Rosner, J.L.
1979-01-01
Conventional estimates are reviewed for charmed particle lifetimes. Free-quark models give values of (a few) x 10/sup -13/ sec to (a few) x 10/sup -12/ sec. The shorter of these values also follows from an extrapolation based on D ..-->.. Ke/sup nu/. Possible differences among the lifetimes and production rates of D/sup 0/, D/sup +/, F/sup +/, C/sub 0//sup +/, the heavy lepton tau, and the fifth quark b are discussed. Extreme values of mixing angles in a six-quark model could extend charmed particle lifetimes by a factor of at most three from the above estimates, while shorter lifetimes than those predicted could occur for some species like D/sup 0/ or F/sup +/ if their nonleptonic decays were enhanced. The predictions are discussed in the light of some current experimental results, and it is estimated that sigma(pp ..-->.. charm) approx. = 10 ..mu..b at 400 GeV/c. 95 references.
Spectrum of heavy baryons in the quark model
Yoshida, Tetsuya; Hosaka, Atsushi; Oka, Makoto; Sadato, Katsunori
2015-01-01
Single- and double- heavy baryons are studied in the constituent quark model. The model Hamiltonian is chosen as a standard one with two exceptions : (1) The color-Coulomb term depend on quark masses, and (2) an antisymmetric $LS$ force is introduced. Model parameters are fixed by the strange baryon spectra, $\\Lambda$ and $\\Sigma$ baryons. The masses of the observed charmed and bottomed baryons are, then, fairly well reproduced. Our focus is on the low-lying negative-parity states, in which the heavy baryons show specific excitation modes reflecting the mass differences of heavy and light quarks. By changing quark masses from the SU(3) limit to the strange quark mass, further to the charm and bottom quark masses, we demonstrate that the spectra change from the SU(3) symmetry patterns to the heavy quark symmetry ones.
Constituent quark models and pentaquark baryons
Maltman, K
2004-01-01
We discuss certain general features of the pentaquark picture for the theta, its 10bar_F partner, Xi_{3/2}, and possible heavy quark analogues. Models employing spin-dependent interactions based on either effective Goldstone boson exchange or effective color magnetic exchange are also used to shed light on possible corrections to the Jaffe-Wilczek and Karliner-Lipkin scenarios. Some model-dependent features of the pentaquark picture (splitting patterns and relative decay couplings) are also discussed in the context of these models.
Quark model for kaon nucleon scattering
Indian Academy of Sciences (India)
Ahmed Osman
2011-12-01
Kaon nucleon elastic scattering is studied using chiral (3) quark model including antiquarks. Parameters of the present model are essentially based on nucleon–nucleon and nucleon–hyperon interactions. The mass of the scalar meson is taken as 635 MeV. Using this model, the phase shifts of the and partial waves of the kaon nucleon elastic scattering are investigated for isospins 0 and 1. The results of the numerical calculations of different partial waves are in good agreement with experimental data.
Pion production model - connection between dynamics and quark models
Energy Technology Data Exchange (ETDEWEB)
Lee, T.-S. H.; Sato, T.
2000-05-17
The authors discuss the difficulties in testing the hadron models by using the N{sup *} parameters extracted from the empirical amplitude analyses of the {pi}N and {gamma}N reaction data. As an alternative or perhaps a more advantageous approach, they present a Hamiltonian formulation that can relate the pion production dynamics and the constituent quark models of N{sup *} structure. The application of the approach in investigating the {Delta} and N{sup *}(S{sub 11}) excitations is reviewed. It is found that while the {Delta} excitation can be described satisfactory, the {pi}N scattering in S{sub 11} channel can not be described by the constituent quark models based on either the one-gluon-exchange or one-meson-exchange mechanisms. A phenomenological quark-quark potential has been constructed to reproduce the S{sub 11} amplitude.
Effect of temperature gradient on heavy quark anti-quark potential using gravity dual model
Ganesh, S
2016-01-01
The Quark-gluon plasma (QGP) is an expanding fireball, with finite dimensions. Given the finite dimensions, the temperature would be highest at the center, and close to the critical temperature, $T_c$, at the boundary, giving rise to a temperature gradient inside the QGP. A heavy quark anti-quark pair immersed in the QGP medium would see this temperature gradient. The effect of the temperature gradient on the quark anti-quark potential is analyzed using a gravity dual model. The resulting modification to the potential due to the temperature gradient is seen to have a $L^{-2}$ correction term. This could be a possible fallout of the breaking of conformal invariance at finite temperature.
Exotic Quarks in Twin Higgs Models
Cheng, Hsin-Chia; Salvioni, Ennio; Tsai, Yuhsin
2015-01-01
The Twin Higgs model provides a natural theory for the electroweak symmetry breaking without the need of new particles carrying the standard model gauge charges below a few TeV. In the low energy theory, the only probe comes from the mixing of the Higgs fields in the standard model and twin sectors. However, an ultraviolet completion is required below ~ 10 TeV to remove residual logarithmic divergences. In non-supersymmetric completions, new exotic fermions charged under both the standard model and twin gauge symmetries have to be present to accompany the top quark, thus providing a high energy probe of the model. Some of them carry standard model color, and may therefore be copiously produced at current or future hadron colliders. Once produced, these exotic quarks can decay into a top together with twin sector particles. If the twin sector particles escape the detection, we have the irreducible stop-like signals. On the other hand, some twin sector particles may decay back into the standard model particles ...
A supersymmetric composite model of quarks and leptons
Luty, Markus A.; Mohapatra, Rabindra N.
1997-02-01
We present a class of supersymmetric models with complete generations of composite quarks and leptons using recent non-perturbative results for the low energy dynamics of supersymmetric QCD. In these models, the quarks arise as composite ``mesons'' and the leptons emerge as composite ``baryons''. The quark and lepton flavor symmetries are linked at the preon level. Baryon number violation is automatically suppressed by accidental symmetries. We give some speculations on how this model might be made realistic.
Nucleon Spin Content in a Relativistic Quark Potential Model Approach
Institute of Scientific and Technical Information of China (English)
DONG YuBing; FENG QingGuo
2002-01-01
Based on a relativistic quark model approach with an effective potential U(r) = (ac/2)(1 + γ0)r2, the spin content of the nucleon is investigated. Pseudo-scalar interaction between quarks and Goldstone bosons is employed to calculate the couplings between the Goldstone bosons and the nucleon. Different approaches to deal with the center of mass correction in the relativistic quark potential model approach are discussed.
Constituent quark model description of charmonium phenomenology
Segovia, J; Fernandez, F; Hernandez, E
2013-01-01
We review how quark models are able to describe the phenomenology of the charm meson sector. The spectroscopy and decays of charmonium and open charm mesons are described in a particular quark model and compared with the data and the results of other existing models in the literature. A quite reasonable global description of the heavy meson spectra is reached. A new assignment of the $\\psi(4415)$ resonance as a 3D state leaving aside the 4S state to the X(4360) is tested through the analysis of the resonance structure in $e^{+}e^{-}$ exclusive reactions around the $\\psi(4415)$ energy region. We make tentative assignments of some of the $XYZ$ mesons. To elucidate the structure of the $1^{+}$ $c\\bar{s}$ states, i.e. $D_{s1}(2460)$ and $D_{s1}(2536)$, we study the strong decay properties of the $D_{s1}(2536)$ meson. We also perform a calculation of the branching fractions for the semileptonic decays of $B$ and $B_{s}$ mesons into final states containing orbitally excited charmed and charmed-strange mesons, which...
Factorization model for distributions of quarks in hadrons
Ermolaev, B I; Troyan, S I
2015-01-01
We consider distributions of unpolarized (polarized) quarks in unpolarized (polarized) hadrons. Our approach is based on QCD factorization. We begin with study of Basic factorization for the parton-hadron scattering amplitudes in the forward kinematics and suggest a model for non-perturbative contributions to such amplitudes. This model is based on the simple observation: after emitting an active quark by the initial hadron, the remaining set quarks and gluons becomes unstable, so description of this colored state can approximately be done in terms of resonances, which leads to expressions of the Breit-Wigner type. for non-perturbative contributions to the distributions of unpolarized and polarized quarks in the hadrons. Then we reduce these formulae to obtain explicit expressions for the quark-hadron scattering amplitudes and quark distributions in K_T- and Collinear factorizations.
Two types of glitches in a solid quark star model
Lu, Jiguang
2015-01-01
The glitch of anomalous X-ray pulsars \\& soft gamma repeaters (AXP/SGRs) usually accompanied with detectable energy releases manifesting as X-ray bursts or outbursts, while the glitch of some pulsars like Vela release negligible energy. We find that these two types of glitch can naturally correspond to two types of starquake of solid stars. So far only quark star and quark cluster star model develop a solid star model. Then the two types of glitch may be an implication that the pulsar is composed by quark matter or quark cluster matter.
Recent results in the NJL model with heavy quarks
Feldmann, T
1996-01-01
We investigate the interplay of chiral and heavy quark symmetries by using the NJL quark model. Heavy quarks with finite masses m(Q) as well as the limit m(Q) to infinity are studied. We found large corrections to the heavy mass scaling law for the pseudoscalar decay constant. The influence of external momenta on the shape parameters of the Isgur-Wise form factor is discussed.
The Spectral Quark Model and Light Cone Phenomenology
Ruiz-Arriola, E; Broniowsk, Wojciech
2003-01-01
Chiral quark models offer a practical and simple tool to describe covariantly both low and high energy phenomenology in combination with QCD evolution. This can be done in full harmony with chiral symmetry and electromagnetic gauge invariance. We review the recently proposed spectral quark model where all these constraints are implemented.
The ccbar Pentaquarks by a Quark Model
Takeuchi, Sachiko
2016-01-01
Recent LHCb experiments have shown us that there are two resonances in the $J/\\psi p$ channel in the $\\Lambda_b$ decay, whose spin and parity are most probably (3/2$^-$ 5/2$^+$). In this work, we investigate the $I(J^P)=1/2(1/2^-)$, $1/2(3/2^-)$, and $1/2(5/2^-)$ $uudc{\\bar c}$ pentaquark states by employing the quark cluster model. It is found that the color-octet isospin-1/2 spin-3/2 $uud$ configuration gives an attraction to such five-quark systems. This configuration together with the color-octet $c{\\bar c}$ pair gives structures around the $\\Sigma_c^{(*)}{\\bar D}{}^{(*)}$ thresholds: one bound state, two resonances, and one large cusp are found in the $uudc{\\bar c}$ negative parity channels. We argue that these resonances and cusp may correspond to, or combine to form, the negative parity pentaquark peak observed by LHCb.
The Quark Model and $b$ Baryons
Karliner, Marek; Lipkin, Harry J; Rosner, Jonathan L
2008-01-01
The recent observation at the Tevatron of $\\Sigma_b^{\\pm}$ ($uub$ and $ddb$) baryons within 2 MeV of the predicted $\\Sigma_b - \\Lambda_b$ splitting and of $\\Xi_b^-$ $(dsb)$ baryons at the Tevatron within a few MeV of predictions has provided strong confirmation for a theoretical approach based on modeling the color hyperfine interaction. The prediction of $M(\\Xi^-_b) = 5790$ to 5800 MeV is reviewed and similar methods used to predict the masses of the excited states $\\Xi_b^\\prime$ and $\\Xi_b^*$. The main source of uncertainty is the method used to estimate the mass difference $m_b - m_c$ from known hadrons. We verify that corrections due to the details of the interquark potential and to $\\Xi_b$--$\\Xi_b^\\prime$ mixing are small. For S-wave $qqb$ states we predict $M(\\Omega_b) = 6052.1 \\pm 5.6$ MeV, $M(\\Omega^*_b) = 6082.8 \\pm 5.6$ MeV, and $M(\\Xi_b^0) = 5786.7 \\pm 3.0$ MeV. For states with one unit of orbital angular momentum between the $b$ quark and the two light quarks we predict $M(\\Lambda_{b[1/2]}) = 5929...
Dibaryons with two strange quarks and one heavy flavor in a constituent quark model
Park, Aaron; Park, Woosung; Lee, Su Houng
2016-09-01
We investigate the symmetry property and the stability of dibaryons containing two strange quarks and one heavy flavor with isospin I =1/2 . We construct the wave function of the dibaryon in two ways. First, we directly construct the color and spin state of the dibaryon starting from the four possible S U (3 ) flavor states. Second, we consider the states composed of five light quarks and then construct the wave function of the dibaryon by adding one heavy quark. The stability of the dibaryon against the strong decay into two baryons is discussed by using the variational method in a constituent quark model with a confining and hyperfine potential. We find that, for all configurations with spin S =0 , 1, 2, the ground states of the dibaryons are the sum of two baryons, and there is no compact bound state that is stable against the strong decay.
Dibaryons with two strange quarks and one heavy flavor in a constituent quark model
Park, Aaron; Lee, Su Houng
2016-01-01
We investigate the symmetry property and the stability of dibaryons containing two strange quarks and one heavy flavor with $I=\\frac{1}{2}$. We construct the wave function of the dibaryon in two ways. First, we directly construct the color and spin state of the dibaryon starting from the four possible SU(3) flavor state. Second, we consider the states composed of five light quarks, and then construct the wave function of the dibaryon by adding one heavy quark. The stability of the dibaryon against the strong decay into two baryons is discussed by using variational method in a constituent quark model with confining and hyperfine potential. We find that for all configurations with S=0,1,2, the ground states of the dibaryons are the sum of two baryons, and there are no compact bound state that is stable against the strong decay.
A Model of Quark and Lepton Mixing and Mass Hierarchy
Barr, S M
2015-01-01
It is shown that an idea proposed in 1996 that relates in a qualitatively correct way the inter-family mass hierarchies of the up quarks, down quarks, charged leptons, and neutrinos, can be combined with a predictive scheme recently proposed for relating quark mixing and neutrino mixing. In the resulting model, the entire flavor structure of the quarks and leptons is expressible in terms of two "master matrices": a diagonal matrix that gives the inter-family mass ratios, and an off-diagonal matrix that controls all flavor mixing.
Relativistic quark model and pentaquark spectroscopy
Gerasyuta, S M
2002-01-01
The relativistic five-quark equations are found in the framework of the dispersion relation technique. The solutions of these equations using the method based on the extraction of leading singularities of the amplitudes are obtained. The five-quark amplitudes for the low-lying pentaquarks are calculated under the condition that flavor SU(3) symmetry holds. The poles of five-quark amplitudes determine the masses of the lowest pentaquarks. The mass spectra of pentaquarks which contain only light quarks are calculated. The calculation of pentaquark amplitudes estimates the contributions of three subamplitudes. The main contributions to the pentaquark amplitude are determined by the subamplitudes, which include the meson states.
Relativistic quark model for the Omega- electromagnetic form factors
Energy Technology Data Exchange (ETDEWEB)
G. Ramalho, K. Tsushima, Franz Gross
2009-08-01
We compute the Omega- electromagnetic form factors and the decuplet baryon magnetic moments using a quark model application of the Covariant Spectator Theory. Our predictions for the Omega- electromagnetic form factors can be tested in the future by lattice QCD simulations at the physical strange quark mass.
A relativistic quark model for the Omega- electromagnetic form factors
Ramalho, G; Gross, Franz
2009-01-01
We compute the Omega- electromagnetic form factors and the decuplet baryon magnetic moments using a quark model application of the Covariant Spectator Theory. Our predictions for the Omega- electromagnetic form factors can be tested in the future by lattice QCD simulations at the physical strange quark mass.
Light baryons in a constituent quark model with chiral dynamics
Glozman, L Ya; Plessas, W
1996-01-01
It is shown from rigorous three-body Faddeev calculations that the masses of all 14 lowest states in the N and \\Delta spectra can be described within a constituent quark model with a Goldstone-boson-exch ange interaction plus linear confinement between the constituent quarks.
The Thomas-Fermi Quark Model: Non-Relativistic Aspects
Liu, Quan
2012-01-01
Non-relativistic aspects of the Thomas-Fermi statistical quark model are developed. A review is given and our modified approach to spin in the model is explained. Our results are limited so far to two inequivalent simultaneous wave functions which can apply to multiple degenerate flavors. An explicit spin interaction is introduced, which requires the introduction of a generalized spin "flavor". Although the model is designed to be most reliable for many-quark states, we find surprisingly that it may be used to fit the low energy spectrum of octet and decouplet baryons. The low energy fit allows us to investigate the six-quark doubly strange H-dibaryon state, possible 6 quark nucleon-nucleon resonances and flavor symmetric strange states of higher quark content.
Strange baryon spectroscopy in the relativistic quark model
Faustov, R N
2015-01-01
Mass spectra of strange baryons are calculated in the framework of the relativistic quark model based on the quasipotential approach. Baryons are treated as the relativistic quark-diquark bound systems. It is assumed that two quarks with equal constituent masses form a diquark. The diquark excitations and its internal structure are consistently taken into account. Calculations are performed up to rather high orbital and radial excitations of strange baryons. On this basis the Regge trajectories are constructed. The obtained results are compared with available experimental data and previous predictions. It is found that all masses of the 4- and 3-star, as well as most of the 2- and 1-star states of strange baryons with established quantum numbers are well reproduced. The developed relativistic quark-diquark model predicts less excited states than three-quark models of strange baryons.
Strange baryon spectroscopy in the relativistic quark model
Faustov, R. N.; Galkin, V. O.
2015-09-01
Mass spectra of strange baryons are calculated in the framework of the relativistic quark model based on the quasipotential approach. Baryons are treated as relativistic quark-diquark bound systems. It is assumed that two quarks with equal constituent masses form a diquark. The diquark excitations and its internal structure are consistently taken into account. Calculations are performed up to rather high orbital and radial excitations of strange baryons. On this basis the Regge trajectories are constructed. The obtained results are compared with available experimental data and previous predictions. It is found that all masses of the 4- and 3-star states of strange baryons with established quantum numbers, as well as most of the 2- and 1-star states, are well reproduced. The developed relativistic quark-diquark model predicts less excited states than three-quark models of strange baryons.
Factorization model for distributions of quarks in hadrons
Energy Technology Data Exchange (ETDEWEB)
Ermolaev, B.I. [Ioffe Physico-Technical Institute, St. Petersburg (Russian Federation); Greco, M. [University Roma Tre, Department of Mathematics and Physics, Rome (Italy); INFN, Rome (Italy); Troyan, S.I. [St. Petersburg Institute of Nuclear Physics, Gatchina (Russian Federation)
2015-07-15
We consider distributions of unpolarized (polarized) quarks in unpolarized (polarized) hadrons. Our approach is based on QCD factorization. We begin with a study of the basic factorization for the parton-hadron scattering amplitudes in the forward kinematics and suggest a model for non-perturbative contributions to such amplitudes. This model is based on this simple observation: after emitting an active quark by the initial hadron, the remaining set of quarks and gluons becomes unstable, so a description of this colored state can approximately be done in terms of resonances, which leads to expressions of the Breit-Wigner type. Then we reduce these formulas to obtain explicit expressions for the quark-hadron scattering amplitudes and quark distributions in K{sub T}- and collinear factorizations. (orig.)
Bulk viscosity of strange quark matter in density dependent quark mass model
Indian Academy of Sciences (India)
J D Anand; N Chandrika Devi; V K Gupta; S Singh
2000-05-01
We have studied the bulk viscosity of strange quark matter in the density dependent quark mass model (DDQM) and compared results with calculations done earlier in the MIT bag model where , masses were neglected and ﬁrst order interactions were taken into account. We ﬁnd that at low temperatures and high relative perturbations, the bulk viscosity is higher by 2 to 3 orders of magnitude while at low perturbations the enhancement is by 1–2 order of magnitude as compared to earlier results. Also the damping time is 2–3 orders of magnitude lower implying that the star reaches stability much earlier than in MIT bag model calculations.
Quark-gluon double parton distributions in the light-front dressed quark model
Kasemets, Tomas
2016-01-01
We study parton distributions for two partons, a quark and a gluon, in the light-front dressed quark model, with focus on correlations between the two partons. The model calculation leads to sizable spin-spin and spin-kinematic correlations of interest for studies of double parton scattering (DPS) in high-energy collisions. In particular, we find that the transverse dependence of the double parton distributions (DPDs) does not factorize within the model. The results gives insight to the strengths of correlations in different kinematical regions, which can help in constructing input DPDs in cross section calculations.
The state of cold quark matter: a model-independent view
Xu, Renxin
2009-01-01
From a model-independent point of view, we address the possibility that quark clustering could occur in cold quark matter at realistic baryon densities because of the likely strong coupling between quarks in compact stars.
Modeling Quark Gluon Plasma Using CHIMERA
Abelev, Betty
2011-09-01
We attempt to model Quark Gluon Plasma (QGP) evolution from the initial Heavy Ion collision to the final hadronic gas state by combining the Glauber model initial state conditions with eccentricity fluctuations, pre-equilibrium flow, UVH2+1 viscous hydrodynamics with lattice QCD Equation of State (EoS), a modified Cooper-Frye freeze-out and the UrQMD hadronic cascade. We then evaluate the model parameters using a comprehensive analytical framework which together with the described model we call CHIMERA. Within our framework, the initial state parameters, such as the initial temperature (Tinit), presence or absence of initial flow, viscosity over entropy density (η/S) and different Equations of State (EoS), are varied and then compared simultaneously to several experimental data observables: HBT radii, particle spectra and particle flow. χ2/nds values from comparison to the experimental data for each set of initial parameters will then used to find the optimal description of the QGP with parameters that are difficult to obtain experimentally, but are crucial to understanding of the matter produced.
Modeling Quark Gluon Plasma Using CHIMERA
Abelev, Betty B I
2011-01-01
We attempt to model Quark Gluon Plasma (QGP) evolution from the initial Heavy Ion collision to the final hadronic gas state by combining the Glauber model initial state conditions with eccentricity fluctuations, pre-equilibrium flow, UVH2+1 viscous hydrodynamics with lattice QCD Equation of State (EoS), a modified Cooper-Frye freeze-out and the UrQMD hadronic cascade. We then evaluate the model parameters using a comprehensive analytical framework which together with the described model we call CHIMERA. Within our framework, the initial state parameters, such as the initial temperature (T$_{\\mathrm{init}}$), presence or absence of initial flow, viscosity over entropy density ($\\eta$/s) and different Equations of State (EoS), are varied and then compared simultaneously to several experimental data observables: HBT radii, particle spectra and particle flow. $\\chi^2$/nds values from comparison to the experimental data for each set of initial parameters will then used to find the optimal description of the QGP wi...
Baryon Wave Functions in Covariant Relativistic Quark Models
Dillig, M
2002-01-01
We derive covariant baryon wave functions for arbitrary Lorentz boosts. Modeling baryons as quark-diquark systems, we reduce their manifestly covariant Bethe-Salpeter equation to a covariant 3-dimensional form by projecting on the relative quark-diquark energy. Guided by a phenomenological multigluon exchange representation of a covariant confining kernel, we derive for practical applications explicit solutions for harmonic confinement and for the MIT Bag Model. We briefly comment on the interplay of boosts and center-of-mass corrections in relativistic quark models.
Heavy quark potential from deformed AdS5 models
Zhang, Zi-qiang; Hou, De-fu; Chen, Gang
2017-04-01
In this paper, we investigate the heavy quark potential in some holographic QCD models. The calculation relies on a modified renormalization scheme mentioned in a previous work of Albacete et al. After studying the heavy quark potential in Pirner-Galow model and Andreev-Zakharov model, we extend the discussion to a general deformed AdS5 case. It is shown that the obtained potential is negative definite for all quark-antiquark separations, differs from that using the usual renormalization scheme.
A radiative model of quark masses with binary tetrahedral symmetry
Natale, Alexander
2017-01-01
A radiative model of quark and lepton masses utilizing the binary tetrahedral (T‧) flavor symmetry, or horizontal symmetry, is proposed which produces the first two generation of quark masses through their interactions with vector-like quarks that carry charges under an additional U (1). By softly-breaking the T‧ to a residual Z4 through the vector-like quark masses, a CKM mixing angle close to the Cabibbo angle is produced. In order to generate the cobimaximal neutrino oscillation pattern (θ13 ≠ 0 ,θ23 = π / 4 ,δCP = ± π / 2) and protect the horizontal symmetry from arbitrary corrections in the lepton sector, there are automatically two stabilizing symmetries in the dark sector. Several benchmark cases where the correct relic density is achieved in a multi-component DM scenario, as well as the potential collider signatures of the vector-like quarks are discussed.
Preon Trinity a new model of leptons and quarks
Dugne, J J; Hansson, J; Predazzi, Enrico; Dugne, Jean-Jacques; Fredriksson, Sverker; Hansson, Johan; Predazzi, Enrico
1999-01-01
A new model for the substructure of quarks, leptons and weak gauge bosons, is discussed. It is based on three fundamental and absolutely stable spin-1/2 preons. Its preon flavour SU(3) symmetry leads to a prediction of nine quarks, nine leptons and nine heavy vector bosons. One of the quarks has charge $-4e/3$, and is speculated to be the top quark (whose charge has not been measured). The flavour symmetry leads to three conserved lepton numbers in all known weak processes, except for some neutrinos, which might either oscillate or decay. There is also a (Cabibbo) mixing of the $d$ and $s$ quarks due to an internal preon-antipreon annihilation channel. An identical channel exists inside the composite $Z^0$, leading to a relation between the Cabibbo and Weinberg mixing angles.
Pentaquark with diquark correlations in a quark model
Takeuchi, S; Takeuchi, Sachiko; Shimizu, Kiyotaka
2004-01-01
We have investigated uudd\\sbar pentaquarks by employing quark models with the meson exchange and the effective gluon exchange as qq and q\\qbar interactions. The system for five quarks is dynamically solved; two quarks are allowed to have a diquark-like qq correlation. It is found that the lowest mass of the pentaquark is about 1947 -- 2144 MeV. There are parameter sets where the mass of the lowest positive-parity state become lower than that of the negative-parity states. Which parity corresponds to the observed peak is still an open question. Relative distance of two quarks with the attractive interaction is found to be by about 1.2 -- 1.3 times closer than that of the repulsive one. The diquark-like quark correlation seems to play an important role in the pentaquark systems.
Chiral Dynamics of Baryons in a Lorentz Covariant Quark Model
Faessler, A; Lyubovitskij, V E; Pumsa-ard, K; Faessler, Amand; Gutsche, Th.
2006-01-01
We develop a manifestly Lorentz covariant chiral quark model for the study of baryons as bound states of constituent quarks dressed by a cloud of pseudoscalar mesons. The approach is based on a non-linear chirally symmetric Lagrangian, which involves effective degrees of freedom - constituent quarks and the chiral (pseudoscalar meson) fields. In a first step, this Lagrangian can be used to perform a dressing of the constituent quarks by a cloud of light pseudoscalar mesons and other heavy states using the calculational technique of infrared dimensional regularization of loop diagrams. We calculate the dressed transition operators with a proper chiral expansion which are relevant for the interaction of quarks with external fields in the presence of a virtual meson cloud. In a second step, these dressed operators are used to calculate baryon matrix elements. Applications are worked out for the masses of the baryon octet, the meson-nucleon sigma terms, the magnetic moments of the baryon octet, the nucleon charge...
Magnetic moments of heavy baryons in the relativistic three-quark model
Faessler, A; Ivanov, M A; Körner, J G; Lyubovitskij, V E; Nicmorus, D; Pumsa-ard, K; Faessler, Amand; Gutsche, Th.
2006-01-01
The magnetic moments of ground state single, double and triple heavy baryons containing charm or bottom quarks are calculated in a relativistic three-quark model, which, in the heavy quark limit, is consistent with Heavy Quark Effective Theory and Heavy Hadron Chiral Perturbation Theory. The internal quark structure of baryons is modeled by baryonic three-quark currents with a spin-flavor structure patterned according to standard covariant baryonic wave functions and currents used in QCD sum rule calculations.
Effective models for interacting quarks from QCD
Energy Technology Data Exchange (ETDEWEB)
Braghin, Fabio L. [Universidade Federal de Goias (UFG), Goiania, GO (Brazil). Inst. de Fisica
2012-07-01
Full text: In this work the Quantum Chromodynamics ( QCD ) path integral is considered with the introduction of auxiliary variables for composite gluon fields. One of these variables eventually leads to the gluon condensates of order 2 and another one corresponds to an anti - symmetric composite gluon configuration. Gluon degrees of freedom, and part of the quark degrees of freedom, are integrated out and two different limits of the resulting effective quark interactions are analysed. (author)
Chiral symmetry and the constituent quark model
Glozman, L Ya
1995-01-01
New results on baryon structure and spectrum developed in collaboration with Dan Riska [1-4] are reported. The main idea is that beyond the chiral symmetry spontaneous breaking scale light and strange baryons should be considered as systems of three constituent quarks with an effective confining interaction and a chiral interaction that is mediated by the octet of Goldstone bosons (pseudoscalar mesons) between the constituent quarks.
Baryons in chiral constituent quark model
Glozman, L Ya
1996-01-01
Beyond the spontaneous chiral symmetry breaking scale light and strange baryons should be considered as systems of three constituent quarks with an effective confining interaction and a flavor-spin chiral interaction that is mediated by the octet of Goldstone bosons (pseudoscalar mesons) between the constituent quarks. One cannot exclude, however, the possibility that this flavor-spin interaction has an appreciable vector- and higher meson exchange component.
Nonlocal quark model description of a composite Higgs particle
Kachanovich, Aliaksei
2016-01-01
We propose a description of the Higgs boson as top-antitop quark bound state within a nonlocal relativistic quark model of Nambu - Jona-Lasinio type. In contrast to model with local four-fermion interaction, the mass of the scalar bound state can be lighter than the sum of its constituents. This is achieved by adjusting the interaction range and the value of the coupling constant to experimental data, for both the top quark mass and the scalar Higgs boson mass, which can simultaneously be described.
Effective Q-Q Interactions in Constituent Quark Models
Glozman, L Ya; Plessas, W; Varga, K; Wagenbrun, R F
1998-01-01
We study the performance of some recent potential models suggested as effective interactions between constituent quarks. In particular, we address constituent quark models for baryons with hybrid Q-Q interactions stemming from one-gluon plus meson exchanges. Upon recalculating two of such models we find them to fail in describing the N and \\Delta spectra. Our calculations are based on accurate solutions of the three-quark systems in both a variational Schrödinger and a rigorous Faddeev approach. It is argued that hybrid {Q-Q} interactions encounter difficulties in describing baryon spectra due to the specific contributions from one-gluon and pion exchanges together. In contrast, a chiral constituent quark model with a Q-Q interaction solely derived from Goldstone-boson exchange is capable of providing a unified description of both the N and \\Delta spectra in good agreement with phenomenology.
Improved Nucleon Properties in the Extended Quark Sigma Model
Abu-Shady, M
2013-01-01
The quark sigma model describes the quarks interacting via exchange the pions and sigma meson fields. A new version of mesonic potential is suggested in the frame of some aspects of the quantum chromodynamics (QCD). The field equations have been solved in the mean-field approximation for the hedgehog baryon state. The obtained results are compared with previous works and other models. We conclude that the suggested mesonic potential successfully calculates nucleon properties.
Modelling hybrid stars in quark-hadron approaches
Energy Technology Data Exchange (ETDEWEB)
Schramm, S. [FIAS, Frankfurt am Main (Germany); Dexheimer, V. [Kent State University, Department of Physics, Kent, OH (United States); Negreiros, R. [Federal Fluminense University, Gragoata, Niteroi (Brazil)
2016-01-15
The density in the core of neutron stars can reach values of about 5 to 10 times nuclear matter saturation density. It is, therefore, a natural assumption that hadrons may have dissolved into quarks under such conditions, forming a hybrid star. This star will have an outer region of hadronic matter and a core of quark matter or even a mixed state of hadrons and quarks. In order to investigate such phases, we discuss different model approaches that can be used in the study of compact stars as well as being applicable to a wider range of temperatures and densities. One major model ingredient, the role of quark interactions in the stability of massive hybrid stars is discussed. In this context, possible conflicts with lattice QCD simulations are investigated. (orig.)
The Phase Structure of the Polyakov--Quark-Meson Model
Schaefer, Bernd-Jochen; Wambach, Jochen
2007-01-01
The relation between the deconfinement and chiral phase transition is explored in the framework of an Polyakov-loop-extended two-flavor quark-meson (PQM) model. In this model the Polyakov loop dynamics is represented by a background temporal gauge field which also couples to the quarks. As a novelty an explicit quark chemical potential and N_f-dependence in the Polyakov loop potential is proposed by using renormalization group arguments. The behavior of the Polyakov loop as well as the chiral condensate as function of temperature and quark chemical potential is obtained by minimizing the grand canonical thermodynamic potential of the system. The effect of the Polyakov loop dynamics on the chiral phase diagram and on several thermodynamic bulk quantities is presented.
Phase structure of the Polyakov-quark-meson model
Schaefer, B.-J.; Pawlowski, J. M.; Wambach, J.
2007-10-01
The relation between the deconfinement and chiral phase transition is explored in the framework of a Polyakov-loop-extended two-flavor quark-meson (PQM) model. In this model the Polyakov loop dynamics is represented by a background temporal gauge field which also couples to the quarks. As a novelty an explicit quark chemical potential and Nf-dependence in the Polyakov loop potential is proposed by using renormalization group arguments. The behavior of the Polyakov loop as well as the chiral condensate as function of temperature and quark chemical potential is obtained by minimizing the grand canonical thermodynamic potential of the system. The effect of the Polyakov loop dynamics on the chiral phase diagram and on several thermodynamic bulk quantities is presented.
A Euclidean bridge to the relativistic constituent quark model
Hobbs, T J; Miller, Gerald A
2016-01-01
${\\bf Background}$ Knowledge of nucleon structure is today ever more of a precision science, with heightened theoretical and experimental activity expected in coming years. At the same time, a persistent gap lingers between theoretical approaches grounded in Euclidean methods (e.g., lattice QCD, Dyson-Schwinger Equations [DSEs]) as opposed to traditional Minkowski field theories (such as light-front constituent quark models). ${\\bf Purpose}$ Seeking to bridge these complementary worldviews, we explore the potential of a Euclidean constituent quark model (ECQM). This formalism enables us to study the gluonic dressing of the quark-level axial-vector vertex, which we undertake as a test of the framework. ${\\bf Method}$ To access its indispensable elements with a minimum of inessential detail, we develop our ECQM using the simplified quark $+$ scalar diquark picture of the nucleon. We construct a hyperspherical formalism involving polynomial expansions of diquark propagators to marry our ECQM with the results of ...
Nucleon polarizabilities in the perturbative chiral quark model
Dong, Y; Gutsche, T; Kuckei, J; Lyubovitskij, V E; Pumsa-ard, K; Shen, P; Faessler, Amand; Gutsche, Th.
2006-01-01
The nucleon polarizabilities alpha(E) and beta(M) are studied in the context of the perturbative chiral quark model. We demonstrate that meson cloud effects are sufficient to explain the electric polarizability of nucleon. Contributions of excite quark states to the paramagnetic polarizability are dominant and cancel the diamagnetic polarizability arising from the chiral field. The obtained results are compared to data and other theoretical predictions.
Radiative transitions in mesons in a non relativistic quark model
Bonnaz, R.; Silvestre-Brac, B.; Gignoux, C.
2001-01-01
In the framework of the non relativistic quark model, an exhaustive study of radiative transitions in mesons is performed. The emphasis is put on several points. Some traditional approximations (long wave length limit, non relativistic phase space, dipole approximation for E1 transitions, gaussian wave functions) are analyzed in detail and their effects commented. A complete treatment using three different types of realistic quark-antiquark potential is made. The overall agreement with experi...
Radiative transitions in mesons in a non relativistic quark model
Bonnaz, R; Gignoux, C
2002-01-01
In the framework of the non relativistic quark model, an exhaustive study of radiative transitions in mesons is performed. The emphasis is put on several points. Some traditional approximations (long wave length limit, non relativistic phase space, dipole approximation for E1 transitions, gaussian wave functions) are analyzed in detail and their effects commented. A complete treatment using three different types of realistic quark-antiquark potential is made. The overall agreement with experimental data is quite good, but some improvements are suggested.
A Diquark-Quark Model with Its Use in Nucleon Form Factors
Institute of Scientific and Technical Information of China (English)
WANG Hong-Min; ZHANG Ben-Ai
2005-01-01
The nucleon electromagnetic form factors are investigated within a simple diquark-quark model using the light-front formalism. In this model, baryon is described as a bound state of one quark and one clustering diquark.The calculational results are compared with the experimental ones. We also regard the quarks in a baryon as pointlike constituent quarks.
A light front quark-diquark model for the nucleons
Maji, Tanmay
2016-01-01
We present a quark-diquark model for the nucleons where the light front wave functions are constructed from the soft-wall AdS/QCD prediction. The model is consistent with quark counting rule and Drell-Yan-West relation. The model reproduces the scale evolution of unpolarized PDF of proton for a wide range of energy scale. Helicity and transversity distributions for the proton predicted in this model agree with phenomenological fits. The axial and tensor charges are also shown to agree with the experimental data. The model can be used to evaluate distributions like GPDS, TMDs etc. and their scale evolutions.
The quark mean field model with pion and gluon corrections
Xing, Xueyong; Shen, Hong
2016-01-01
The properties of nuclear matter and finite nuclei are studied within the quark mean field (QMF) model by taking the effects of pion and gluon into account at the quark level. The nucleon is described as the combination of three constituent quarks confined by a harmonic oscillator potential. To satisfy the spirit of QCD theory, the contributions of pion and gluon on the nucleon structure are treated in second-order perturbation theory. For the nuclear many-body system, nucleons interact with each other by exchanging mesons between quarks. With different constituent quark mass, $m_q$, we determine three parameter sets about the coupling constants between mesons and quarks, named as QMF-NK1, QMF-NK2, and QMF-NK3 by fitting the ground-state properties of several closed-shell nuclei. It is found that all of the three parameter sets can give satisfactory description on properties of nuclear matter and finite nuclei, meanwhile they can also predict the larger neutron star mass around $2.3M_\\odot$ without the hypero...
Quark mean field model with pion and gluon corrections
Xing, Xueyong; Hu, Jinniu; Shen, Hong
2016-10-01
The properties of nuclear matter and finite nuclei are studied within the quark mean field (QMF) model by taking the effects of pions and gluons into account at the quark level. The nucleon is described as the combination of three constituent quarks confined by a harmonic oscillator potential. To satisfy the spirit of QCD theory, the contributions of pions and gluons on the nucleon structure are treated in second-order perturbation theory. In a nuclear many-body system, nucleons interact with each other by exchanging mesons between quarks. With different constituent quark mass, mq, we determine three parameter sets for the coupling constants between mesons and quarks, named QMF-NK1, QMF-NK2, and QMF-NK3, by fitting the ground-state properties of several closed-shell nuclei. It is found that all of the three parameter sets can give a satisfactory description of properties of nuclear matter and finite nuclei, moreover they also predict a larger neutron star mass around 2.3 M⊙ without hyperon degrees of freedom.
Top quark pair production and modeling via QCD in CMS
Gonzalez Fernandez, Juan Rodrigo
2017-01-01
Measurements of the inclusive and differential top quark pair ($\\textrm{t}\\bar{\\textrm{t}}$~) production cross section at centre-of-mass energies of 13 TeV and 5.02 TeV are presented, performed using CMS data collected in 2015 and 2016. The inclusive cross section is measured in the lepton+jets, dilepton and fully hadronic channels. Top quark pair differential cross sections are measured and are given as functions of various kinematic observables of (anti)top quark, the $\\textrm{t}\\bar{\\textrm{t}}$~ system, and of the jets and leptons in the final state. Furthermore, the multiplicity and kinematic distributions of the additional jets produced in $\\textrm{t}\\bar{\\textrm{t}}$~ events are also investigated and its modeling is compared for several generators. A new tune of parameters is developed for some of the generators. In addition, first measurements of top quark pair production with additional b quarks in the final state are presented. Furthermore, searches for four top quark production in CMS are also pres...
Chiral dynamics of baryons in the perturbative chiral quark model
Energy Technology Data Exchange (ETDEWEB)
Pumsa-ard, K.
2006-07-01
In this work we develop and apply variants of a perturbative chiral quark model (PCQM) to the study of baryonic properties dominantly in the low-energy region. In a first step we consider a noncovariant form of the PCQM, where confinement is modelled by a static, effective potential and chiral corrections are treated to second order, in line with similar chiral quark models. We apply the PCQM to the study of the electromagnetic form factors of the baryon octet. We focus in particular on the low-energy observables such as the magnetic moments, the charge and magnetic radii. In addition, the electromagnetic N-delta transition is also studied in the framework of the PCQM. In the chiral loop calculations we consider a quark propagator, which is restricted to the quark ground state, or in hadronic language to nucleon and delta intermediate states, for simplicity. We furthermore include the low-lying excited states to the quark propagator. In particular, the charge radius of the neutron and the transverse helicity amplitudes of the N-delta transition are considerably improved by this additional effect. In a next step we develop a manifestly Lorentz covariant version of the PCQM, where in addition higher order chiral corrections are included. The full chiral quark Lagrangian is motivated by and in analogy to the one of Chiral Perturbation Theory (ChPT). This Lagrangian contains a set of low energy constants (LECs), which are parameters encoding short distance effects and heavy degrees of freedom. We evaluate the chiral Lagrangian to order O(p{sup 4}) and to one loop to generate the dressing of the bare quark operators by pseudoscalar mesons. In addition we include the vector meson degrees of freedom in our study. Projection of the dressed quark operators on the baryonic level serves to calculate the relevant matrix elements. In a first application of this scheme, we resort to a parameterization of the valence quark form factors in the electromagnetic sector. Constraints
A class of exact strange quark star model
Indian Academy of Sciences (India)
S Thirukkanesh; F C Ragel
2013-08-01
Static spherically symmetric space-time is studied to describe dense compact star with quark matter within the framework of MIT Bag Model. The system of Einstein’s field equations for anisotropic matter is expressed as a new system of differential equations using transformations and it is solved for a particular general form of gravitational potential with parameters. For a particular parameter, as an example, it is shown that the model satisfies all major physical features expected in a realistic star. The generated model also smoothly matches with the Schwarzschild exterior metric at the boundary of the star. It is shown that the generated solutions are useful to model strange quark stars.
Vector-like bottom quarks in composite Higgs models
DEFF Research Database (Denmark)
Gillioz, M.; Grober, R.; Kapuvari, A.
2014-01-01
Like many other models, Composite Higgs Models feature the existence of heavy vector-like quarks. Mixing effects between the Standard Model fields and the heavy states, which can be quite large in case of the top quark, imply deviations from the SM. In this work we investigate the possibility...... be applied to other models with similar particle content. Furthermore, the constraints from direct searches for heavy states at the LHC and from the Higgs search results have been included in our analysis. The best agreement with all the considered constraints is achieved for medium to large compositeness...
Euclidean bridge to the relativistic constituent quark model
Hobbs, T. J.; Alberg, Mary; Miller, Gerald A.
2017-03-01
Background: Knowledge of nucleon structure is today ever more of a precision science, with heightened theoretical and experimental activity expected in coming years. At the same time, a persistent gap lingers between theoretical approaches grounded in Euclidean methods (e.g., lattice QCD, Dyson-Schwinger equations [DSEs]) as opposed to traditional Minkowski field theories (such as light-front constituent quark models). Purpose: Seeking to bridge these complementary world views, we explore the potential of a Euclidean constituent quark model (ECQM). This formalism enables us to study the gluonic dressing of the quark-level axial-vector vertex, which we undertake as a test of the framework. Method: To access its indispensable elements with a minimum of inessential detail, we develop our ECQM using the simplified quark + scalar diquark picture of the nucleon. We construct a hyperspherical formalism involving polynomial expansions of diquark propagators to marry our ECQM with the results of Bethe-Salpeter equation (BSE) analyses, and constrain model parameters by fitting electromagnetic form factor data. Results: From this formalism, we define and compute a new quantity—the Euclidean density function (EDF)—an object that characterizes the nucleon's various charge distributions as functions of the quark's Euclidean momentum. Applying this technology and incorporating information from BSE analyses, we find the quenched dressing effect on the proton's axial-singlet charge to be small in magnitude and consistent with zero, while use of recent determinations of unquenched BSEs results in a large suppression. Conclusions: The quark + scalar diquark ECQM is a step toward a realistic quark model in Euclidean space, and needs additional refinements. The substantial effect we obtain for the impact on the axial-singlet charge of the unquenched dressed vertex compared to the quenched demands further investigation.
Hyperon-Nucleon Interaction in a Quark Model
Oka, M
1993-01-01
A lecture given at the International School Seminar on {\\sl Hadrons and Nuclei from QCD}, Tsuruga-Vladivostok-Sapporo, August-September, 1993. A realistic hyperon ($Y$)-nucleon ($N$) interaction based on the quark model and the one-boson-exchange potential is constructed. The Nijmegen potential model D with the SU(3) flavor symmetry is modified with a quark exchange interaction at the short-distance, which replaces the short-range repulsive core in the original model. The flavor-spin dependences of the short-range repulsion are qualitatively different from the original hard-core potential. We also study a two-body weak decay, $\\Lambda N \\to NN$, in the quark model. An effective weak interaction, where one-loop QCD corrections are explicitly taken into account, is employed. Differences from the conventional meson-exchange processes are discussed.
ND^(*) and NB^(*) interactions in a chiral quark model
Yang, Dan; Zhang, Dan
2015-01-01
ND and ND^* interactions become a hot topic after the observation of new charmed hadrons \\Sigma_c(2800) and \\Lambda_c(2940)^+. In this letter, we have preliminary investigated S-wave ND and ND^* interactions with possible quantum numbers in the chiral SU(3) quark model and the extended chiral SU(3) quark model by solving the resonating group method equation. The numerical results show that the interactions between N and D or N and D^* are both attractive, which are mainly from \\sigma exchanges between light quarks. Further bound-state studies indicate the attractions are strong enough to form ND or ND^* molecules, except for (ND)_{J=3/2} and (ND^*)_{J=3/2} in the chiral SU(3) quark model. In consequence ND system with J=1/2 and ND^* system with J=3/2 in the extended SU(3) quark model could correspond to the observed \\Sigma_c(2800) and \\Lambda_c(2940)^+, respectively. Naturally, the same method can be applied to research NB and NB^* interactions, and similar conclusions obtained, i.e. NB and NB^* attractive fo...
Ghosh, Sabyasachi; Roy, Victor; Serna, Fernando E; Krein, Gastão
2015-01-01
We have calculated the temperature dependence of shear $\\eta$ and bulk $\\zeta$ viscosities of quark matter due to quark-meson fluctuations. The quark thermal width originating from quantum fluctuations of quark-$\\pi$ and quark-$\\sigma$ loops at finite temperature is calculated with the formalism of real-time thermal field theory. Temperature-dependent constituent-quark and meson masses, and quark-meson couplings are obtained in the Nambu--Jona-Lasinio model. We found a non-trivial influence of the temperature-dependent masses and couplings on the Landau-cut structure of the quark self-energy. Our results for the ratios $\\eta/s$ and $\\zeta/s$, where $s$ is the entropy density (also determined in the Nambu--Jona-Lasinio model in the quasi-particle approximation), are in fair agreement with results of the literature obtained from different models and techniques. In particular, our result for $\\eta/s$ has a minimum very close to the conjectured AdS/CFT lower bound, $\\eta/s = 1/4\\pi$.
Ghosh, Sabyasachi; Peixoto, Thiago C.; Roy, Victor; Serna, Fernando E.; Krein, Gastão
2016-04-01
We have calculated the temperature dependence of shear η and bulk ζ viscosities of quark matter due to quark-meson fluctuations. The quark thermal width originating from quantum fluctuations of quark-π and quark-σ loops at finite temperature is calculated with the formalism of real-time thermal field theory. Temperature-dependent constituent-quark and meson masses and quark-meson couplings are obtained in the Nambu-Jona-Lasinio model. We found a nontrivial influence of the temperature-dependent masses and couplings on the Landau-cut structure of the quark self-energy. Our results for the ratios η /s and ζ /s , where s is the entropy density (also determined in the Nambu-Jona-Lasinio model in the quasiparticle approximation), are in fair agreement with results of the literature obtained from different models and techniques. In particular, our result for η /s has a minimum very close to the quantum lower bound, η /s =1 /4 π .
Non-leptonic decays in an extended chiral quark model
Eeg, J O
2012-01-01
We consider the color suppressed (nonfactorizable) amplitude for the decay mode $\\bar{B_{d}^0} \\rightarrow \\pi^0 \\pi^{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 $\\bar{B_{d}^0} \\rightarrow \\pi^0 \\pi^{0} $ is suppressed by a factor of order $\\Lambda_{QCD}/m_b$ 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 $\\bar{B_{d}^0} \\rightarrow \\pi^0 \\pi^{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 $\\bar{B_{d}^0} \\rightarrow \\pi^...
Glueball-Quarkonium Mixing in the Quark and Chromon Model
Zhang, Pengming; Xie, Ju-Jun; Yoon, J H; Cho, Y M
2016-01-01
The Abelian decomposition of QCD which decomposes the gluons to the color neutral binding gluons (the neurons) and the colored valence gluons (the chromons) gauge independently naturally generalizes the quark model to the quark and chromon model which can play the central role in hadron spectroscopy. We discuss how the quark and chromon model describes the glueballs and the glueball-quarkonium mixing in QCD. We present the numerical analysis of glueball-quarkonium mixing in $0^{++}$, $2^{++}$, and $0^{-+}$ sectors below 2 GeV, and show that in the $0^{++}$ sector $f_0(500)$ and $f_0(1500)$, in the $2^{++}$ sector $f_2(1950)$, and in the $0^{-+}$ sector $\\eta(1405)$ and $\\eta(1475)$ could be identified as predominantly the glueball states. We discuss the physical implications of our result.
Octet baryon electromagnetic form factors in a relativistic quark model
Ramalho, G
2011-01-01
We study the octet baryon electromagnetic properties by applying the covariant spectator quark model, and provide covariant parametrization that can be used to study baryon electromagnetic reactions. While we use the lattice QCD data in the large pion mass regime (small pion cloud effects) to determine the parameters of the model in the valence quark sector, we use the nucleon physical and octet baryon magnetic moment data to parameterize the pion cloud contributions. The valence quark contributions for the octet baryon electromagnetic form factors are estimated by extrapolating the lattice parametrization in the large pion mass regime to the physical regime. As for the pion cloud contributions, we parameterize them in a covariant, phenomenological manner, combined with SU(3) symmetry. We also discuss the impact of the pion cloud effects on the octet baryon electromagnetic form factors and their radii.
New $U(1)'$ model with natural quark mass structure
Martinez, R; Rubio, J P
2013-01-01
We propose a new non-universal $U(1)'$ extension of the standard model with the addition of three exotic quark singlets, two scalar singlets and one additional scalar doublet. By introducing discrete symmetries and mixing couplings between ordinary and exotic fermions, we obtain predictable mass relations in the quark sector compatible with the phenomenological values without large fine tuning of the Yukawa couplings and with few free parameters. We obtain nontrivial constraints between Yukawa constants and mass parameters. For example, the model exhibit a "natural" scenery (in the sense of symmetry) where a large ratio between the top and charm quarks can be obtained by providing Yukawa couplings with a nearly symmetric structure, consistent with a flavor symmetry of the Yukawa couplings.
Octet Baryon Electromagnetic Form Factors in a Relativistic Quark Model
Energy Technology Data Exchange (ETDEWEB)
Gilberto Ramalho, Kazuo Tsushima
2011-09-01
We study the octet baryon electromagnetic properties by applying the covariant spectator quark model, and provide covariant parametrization that can be used to study baryon electromagnetic reactions. While we use the lattice QCD data in the large pion mass regime (small pion cloud effects) to determine the parameters of the model in the valence quark sector, we use the nucleon physical and octet baryon magnetic moment data to parameterize the pion cloud contributions. The valence quark contributions for the octet baryon electromagnetic form factors are estimated by extrapolating the lattice parametrization in the large pion mass regime to the physical regime. As for the pion cloud contributions, we parameterize them in a covariant, phenomenological manner, combined with SU(3) symmetry. We also discuss the impact of the pion cloud effects on the octet baryon electromagnetic form factors and their radii.
Strangeness -2 and -3 Baryons in a Constituent Quark Model
Energy Technology Data Exchange (ETDEWEB)
Muslema Pervin; Winston Roberts
2007-09-19
We apply a quark model developed in earlier work to the spectrum of baryons with strangeness -2 and -3. The model describes a number of well-established baryons successfully, and application to cascade baryons allows the quantum numbers of some known states to be deduced.
A Composite Model of Quarks with the `Effective Supersymmetry'
Okada, N.
1998-04-01
We present a composite model of quarks with `effective supersymmetry'. The model is based on the gauge group (SU(2)S × SU(2)M) × (SU(2)U × SU(2)C × SU(2)T) × SU(5)SM , where SU(5)SM is the standard model gauge group. In the dynamical supersymmetry breaking sector based on the gauge group SU(2)S × SU(2)M , supersymmetry is dynamically broken. The preon sector is constructed by the model proposed by Nelson and Strassler. The fermion mass hierarchy among the up-type quarks originates from the SU(2)U × SU(2)C × SU(2)T gauge dynamics. The supersymmetry breaking is mediated to the minimal supersymmetric standard model sector by the `preon' superfields which compose the quarks in the first two generations. To obtain an experimentally acceptable mass spectrum, the scalar quarks in the first two generations need masses of order 10 TeV, while the other superpartners need masses less than 1 TeV. Therefore, the mass spectrum in our model is one example of the `effective supersymmetry' model proposed by Cohen, Kaplan and Nelson.
A Composite Model of Quarks with the "Effective Supersymmetry"
Okada, N
1998-01-01
We present a composite model of quarks with the `effective supersymmetry'. The model is based on the gauge group $(SU(2)_S \\times SU(2)_M) \\times (SU(2)_U standard model gauge group. In the dynamical supersymmetry breaking sector based on the gauge group $ SU(2)_S \\times SU(2)_M $, the supersymmetry is dynamically broken. The preon sector is constructed by the model proposed by Nelson and Strassler. The fermion mass hierarchy among the up-type quarks originates from the $ SU(2)_U \\times SU(2)_C \\times SU(2)_T $ gauge dynamics. The supersymmetry breaking is mediated to the minimal supersymmetric standard model sector by the `preon' superfields which compose the quarks in the first two generations. To obtain the experimentally acceptable mass spectrum, the scalar quarks in the first two generations have masses of order 10 TeV, while the other superpartners have masses of order 100 GeV. Therefore, the mass spectrum in our model is one of the type of the `effective supersymmetry' model proposed by Cohen, Kaplan a...
Baryons in a chiral constituent quark model
Glozman, L Ya
1998-01-01
In the low-energy regime light and strange baryons should be considered as systems of constituent quarks with confining interaction and a chiral interaction that is mediated by Goldstone bosons as well as by vector and scalar mesons. The flavor-spin structure and sign of the short-range part of the spin-spin force reduces the $SU(6)_{FS}$ symmetry down to $SU(3)_F \\times SU(2)_S$, induces hyperfine splittings and provides correct ordering of the lowest states with positive and negative parity. There is a cancellation of the tensor force from pseudoscalar- and vector-exchanges in baryons. The spin-orbit interactions from $\\rho$-like and $\\omega$-like exchanges also cancel each other in baryons while they produce a big spin-orbit force in NN system. A unified description of light and strange baryon spectra calculated in a semirelativistic framework is presented. It is demonstrated that the same short-range part of spin-spin interaction between the constituent quarks induces a strong short-range repulsion in $NN...
Strangeness s = -3 dibaryons in a chiral quark model
Lian-Rong, D; Chun-Ran, L; Lei, T; Lian-Rong, Dai; Dan, Zhang; Chun-Ran, Li; Lei, Tong
2006-01-01
The structures of $N\\Omega_{(2,1/2)}$ and $\\Delta\\Omega_{(3,3/2)}$ with strangeness $s=-3$ are dynamically studied in both the chiral SU(3) quark model and the extended chiral SU(3) quark model by solving a resonating group method (RGM) equation. The first model parameters are taken from our previous work, which gave a satisfactory description of the energies of the baryon ground states, the binding energy of the deuteron, the nucleon-nucleon(NN) scattering phase shifts, and the hyperon-nucleon (YN) cross sections. The effect from the vector meson fields is very similar to that from the one-gluon exchange interaction, both in the chiral SU(3) quark model and the extended chiral SU(3) quark model, the $N\\Omega_{(2,1/2)}$ and $\\Delta\\Omega_{(3,3/2)}$ systems are wealy bound states. The second model parameters are also taken from our previous work by fitting the KN scattering process. when the mixing of scalar mesons are considered, the $N\\Omega_{(2,1/2)}$ and $\\Delta\\Omega_{(3,3/2)}$ systems change into unbound...
Nuclear symmetry energy in a modified quark meson coupling model
Mishra, R N; Panda, P K; Barik, N; Frederico, T
2015-01-01
We study nuclear symmetry energy and the thermodynamic instabilities of asymmetric nuclear matter in a self-consistent manner by using a modified quark-meson coupling model where the confining interaction for quarks inside a nucleon is represented by a phenomenologically averaged potential in an equally mixed scalar-vector harmonic form. The nucleon-nucleon interaction in nuclear matter is then realized by introducing additional quark couplings to $\\sigma$, $\\omega$, and $\\rho$ mesons through mean-field approximations. We find an analytic expression for the symmetry energy ${\\cal E}_{sym}$ as a function of its slope $L$. Our result establishes a linear correlation between $L$ and ${\\cal E}_{sym}$. We also analyze the constraint on neutron star radii in $(pn)$ matter with $\\beta$ equilibrium.
Remarks on meson loop effects on quark models
Hammer, I K; Nefediev, A V
2016-01-01
We investigate the effect of meson loops on the spectrum of quark states. We demonstrate that in general quark states do not tend to get very broad if their coupling to the continuum increases, but instead they decouple from the latter in the large coupling limit. We ascribe this effect to the essentially nonperturbative unitarization procedure involved. In the meantime, some quark resonances behave very differently and demonstrate collectivity in the sense that their pole trajectories span a wide, as compared to the level spacing, region therefore acquiring contributions from multiple bare poles rather than from the closest neighbours. While the actual calculations are done within particular, very simplified models, it is argued that the findings might well be general.
Structure of pentaquarks Pc+ in the chiral quark model
Yang, Gang; Ping, Jialun; Wang, Fan
2017-01-01
The recent experimental results of the LHCb Collaboration suggested the existence of pentaquark states with a charmonium. To understand the structure of the states, a dynamical calculation of 5-quark systems with quantum numbers I JP=1/2 (1/2 )±,1/2 (3/2 )±and1/2 (5/2 )±is performed in the framework of the chiral quark model with the help of the Gaussian expansion method. The results show that there are several negative parity resonance states while all of the positive parity states are the scattering states. The Pc(4380 ) state is suggested to be the pentaquark state of Σc*D ¯. Although the energy of ΣcD ¯* is very close to the mass of Pc(4450 ), the inconsistent parity prevents the assignment. The calculated distances between quarks confirm the molecular nature of the states.
Octet to decuplet electromagnetic transition in a relativistic quark model
Ramalho, G
2013-01-01
We study the octet to decuplet baryon electromagnetic transitions using the covariant spectator quark model, and predict the transition magnetic dipole form factors for those involving the strange baryons. Utilizing SU(3) symmetry, the valence quark contributions are supplemented by the pion cloud dressing based on the one estimated in the $\\gamma^\\ast N \\to \\Delta$ reaction. Although the valence quark contributions are dominant in general, the pion cloud effects turn out to be very important to describe the experimental data. We also show that, other mesons besides the pion in particular the kaon, may be relevant for some reactions such as $\\gamma^\\ast \\Sigma^+ \\to \\Sigma^{*+}$, based on our analysis for the radiative decay widths of the strange decuplet baryons.
Remarks on meson loop effects on quark models
Energy Technology Data Exchange (ETDEWEB)
Hammer, I.K.; Hanhart, C. [Institut fuer Kernphysik and Juelich Center for Hadron Physics, Forschungszentrum Juelich, Institute for Advanced Simulation, Juelich (Germany); Nefediev, A.V. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); National Research Nuclear University MEPhI, Moscow (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region (Russian Federation)
2016-11-15
We investigate the effect of meson loops on the spectrum of quark states. We demonstrate that in general quark states do not tend to get very broad if their coupling to the continuum increases, but instead they decouple from the latter in the large coupling limit. We ascribe this effect to the essentially nonperturbative unitarization procedure involved. In the meantime, some quark resonances behave very differently and demonstrate collectivity in the sense that their pole trajectories span a wide, as compared to the level spacing, region therefore acquiring contributions from multiple bare poles rather than from the closest neighbors. While the actual calculations are done within particular, very simplified models, it is argued that the findings might well be general. (orig.)
Model-independent measurement of the top quark polarisation
Energy Technology Data Exchange (ETDEWEB)
Aguilar-Saavedra, J.A., E-mail: jaas@ugr.es [Departamento de Fisica Teorica y del Cosmos, Universidad de Granada, Granada (Spain); Instituto de Fisica de Cantabria (CSIC-UC), Santander (Spain); Herrero-Hahn, R.V. [Departamento de Fisica Aplicada, Universidad de Granada, Granada (Spain)
2013-01-08
We introduce a new asymmetry in the decay t{yields}Wb{yields} Script-Small-L {nu}b, which is shown to be directly proportional to the polarisation of the top quark along a chosen axis, times a sum of W helicity fractions. The latter have already been precisely measured at the Tevatron and the Large Hadron Collider. Therefore, this new asymmetry can be used to obtain a model-independent measurement of the polarisation of top quarks produced in any process at hadron or lepton colliders.
Holographic Model of Dual Superconductor for Quark Confinement
Huang, Tsung-Sheng
2016-01-01
We show that a hairy black hole solution can provide a holographically dual description of quark confinement. There exists a one-parameter sensible metric which receives the backreaction of matter contents in the holographic action, where the scalar and gauge field are responsible for the condensation of chromomagnetic monopoles. This model features a preconfining phase triggered by second-order monopole condensation and a first-order confinement/deconfinement phase transition. To confirm the confinement, the quark-antiquark potential is calculated by probing a QCD string in both phases. At last, contribution from Kaluza-Klein monopoles in the confining phase is discussed.
Diquark correlations in baryons: the Interacting Quark Diquark Model
Santopinto, E
2015-01-01
A review of the underlying ideas of the Interacting Quark Diquark Model (IQDM) that asses the baryon spectroscopy in terms of quark diquark degrees of freedom is given, together with a discussion of the missing resonances problem. Some ideas about its generalization the heavy baryon spectroscopy is given.s of freedom is given, together with a discussion of the missing resonances problem. Some ideas about its generalization the heavy baryon spectroscopy is given.The results are compared to the existing experimental data.
Parton distributions for the pion in a chiral quark model
Ruiz-Arriola, E
2001-01-01
Parton distributions for the pion are studied in a chiral quark model characterized by a quark propagator for which a spectral representation is assumed. Electromagnetic and chiral symmetry constraints are imposed through the relevant Ward-Takahashi identities for flavoured vertex functions. Finiteness of the theory, requires the spectral function to be non-positive definite. Straightforward calculation yields the result that the pion structure function becomes one in the chiral limit, regardless of the details of the spectral function. LO and NLO evolution provide a satisfactory description of phenomenological parameterizations of the valence distribution functions but fails to describe gluon and sea distributions.
Quark mixing in the discrete dark matter model
Toorop, Reinier de Adelhart; Morisi, Stefano
2011-01-01
We consider a model in which dark matter is stable as it is charged under a Z2 symmetry that is residual after an A4 flavour symmetry is broken. We consider the possibility to generate the quark masses by charging the quarks appropriately under A4. We find that it is possible to generate the CKM mixing matrix by an interplay of renormalisable and dimension-six operators. In this set-up, we predict the third neutrino mixing angle to be large and the dark matter relic density to be in the correct range. However, low energy observables - in particular meson-antimeson oscillations - strongly limit the available parameter space.
H-particle in a chiral quark model
Shimizu, K
1999-01-01
In this paper we discuss the binding energy of the H-particle using a chiral quark model, where pion exchange plays an important role to reproduce the mass difference between the nucleon and DELTA resonance. Since the main source for the bound H-particle is believed to be the color magnetic interaction, which gives the nucleon and DELTA mass difference, it is very interesting to investigate whether the chiral quark model gives rise to the bound H-particle or not. We employ an extended resonating group method in order to take into account the possibility of a change of baryon wave functions when two baryons interact with each other. We found that a change of baryon size together with the Hamiltonian which consists of gluon, pseudoscalar meson and sigma meson exchange potentials gives rise to the bound H-particle. The binding energy is found to be about 25 MeV in a hybrid chiral quark model. Differences between the ordinary gluon dominant model and chiral quark models are also investigated. It is found that a p...
The quark susceptibility in a generalized dynamical quasiparticle model
Berrehrah, Hamza; Bratkovskaya, Elena; Steinert, Thorsten
2015-01-01
The quark susceptibility $\\chi_q$ at zero and finite quark chemical potential provides a critical benchmark to determine the quark-gluon-plasma (QGP) degrees of freedom in relation to the results from lattice QCD (lQCD) in addition to the equation of state and transport coefficients. Here we extend the familiar dynamical-quasiparticle model (DQPM) to partonic propagators that explicitly depend on the three-momentum with respect to the partonic medium at rest in order to match perturbative QCD (pQCD) at high momenta. Within the extended dynamical-quasi-particle model (DQPM$^*$) we reproduce simultaneously the lQCD results for the quark number density and susceptibility and the QGP pressure at zero and finite (but small) chemical potential $\\mu_q$. The shear viscosity $\\eta$ and the electric conductivity $\\sigma_e$ from the extended quasiparticle model (DQPM$^*$) also turn out in close agreement with lattice results for $\\mu_q$ =0. The DQPM$^*$, furthermore, allows to evaluate the momentum $p$, temperature $T$ ...
Melting of the quark condensate in the NJL model with meson loops
Energy Technology Data Exchange (ETDEWEB)
Florkowski, W.; Broniowski, W. [Institute of Nuclear Physics, Cracow (Poland)
1996-05-01
Temperature dependence of the quark condensate is studied in the Nambu-Jona-Lasinio model with meson loops. Substantial differences are found compared to the results with quark loop only. (author). 13 refs, 3 figs.
Eta and kaon production in a chiral quark model
Energy Technology Data Exchange (ETDEWEB)
Golli, B. [University of Ljubljana and J. Stefan Institute, Faculty of Education, Ljubljana (Slovenia); Sirca, S. [University of Ljubljana and J. Stefan Institute, Faculty of Mathematics and Physics, Ljubljana (Slovenia)
2016-09-15
We apply a coupled-channel formalism incorporating quasi-bound quark-model states to calculate pion scattering into ηN, KΛ and KΣ channels, as well ηp, ηn, K{sup +}Λ, and K{sup 0}Σ{sup +} photoproduction processes. The meson-baryon and photon-baryon vertices are determined in a SU(3) version of the Cloudy Bag Model. Our model predicts sizable amplitudes in the P{sub 11}, P{sub 13}, P{sub 33} and S{sub 11} partial waves in agreement with the latest MAID isobar model and the recent partial-wave analyses of the Bonn-Gatchina group. We are able to give a quark-model explanation for the apparent resonance near 1685 MeV in the ηn channel. (orig.)
Eta and kaon production in a chiral quark model
Golli, Bojan
2016-01-01
We apply a coupled-channel formalism incorporating quasi-bound quark-model states to calculate pion scattering into eta N, K Lambda and K Sigma channels, as well eta p, eta n, K+Lambda, and K0Sigma+ photo-production processes. The meson-baryon and photon-baryon vertices are determined in a SU(3) version of the Cloudy Bag Model. Our model predicts sizable amplitudes in the P11, P13, P33 and S11 partial waves in agreement with the latest MAID isobar model and the recent partial-wave analyses of the Bonn-Gatchina group. We are able to give a quark-model explanation for the apparent resonance at 1685 MeV in the eta n channel.
Light front quark-diquark model for the nucleons
Maji, Tanmay; Chakrabarti, Dipankar
2016-11-01
We present a quark-diquark model for the nucleons where the light front wave functions are constructed from the soft-wall AdS/QCD prediction. The model is consistent with the quark counting rule and Drell-Yan-West relation. The scale evolution of unpolarized parton distribution functions (PDFs) of protons is simulated by making the parameters in the PDF scale dependent. The evolution of the PDFs are reproduced for a wide range of evolution scale. Helicity and transversity distributions for the proton predicted in this model agree with phenomenological fits. The axial and tensor charges are also shown to agree with the experimental data. The model can be used to evaluate distributions like generalized parton distributions, transverse momentum dependent distributions, etc., and their scale evolutions.
Semileptonic Decays of Heavy Omega Baryons in a Quark Model
Pervin, M; Capstick, S; Pervin, Muslema
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 $\\Lambda$ 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 $\\lcle$ rate, with wave functions expanded in both harmonic oscillator and Sturmian bases. Decay rates of $\\ob$ to pairs of ground and excited $\\omc$ 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 elas...
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.
Deeply virtual Compton scattering in a relativistic quark model
Energy Technology Data Exchange (ETDEWEB)
Spitzenberg, T.
2007-09-15
This thesis is mainly concerned with a model calculation for generalized parton distributions (GPDs). We calculate vectorial- and axial GPDs for the N{yields}N and N{yields}{delta} transition in the framework of a light front quark model. This requires the elaboration of a connection between transition amplitudes and GPDs. We provide the first quark model calculations for N{yields}{delta} GPDs. The examination of transition amplitudes leads to various model independent consistency relations. These relations are not exactly obeyed by our model calculation since the use of the impulse approximation in the light front quark model leads to a violation of Poincare covariance. We explore the impact of this covariance breaking on the GPDs and form factors which we determine in our model calculation and find large effects. The reference frame dependence of our results which originates from the breaking of Poincare covariance can be eliminated by introducing spurious covariants. We extend this formalism in order to obtain frame independent results from our transition amplitudes. (orig.)
Superconducting phases of strange quark matter in the NJL model
Paulucci, L; Ferrer, E J; de la Incera, V
2013-01-01
We analyze the color-flavor-locked phase of strange quark matter modelled by the three-flavor Nambu-Jona-Lasinio (NJL) framework with and without magnetic field and discuss some additional constraints on the stability scenario when a high magnetic field is applied. We compare the results obtained by employing the MIT Bag Model and discuss the pairing gap behavior and its influence on the equation of state.
Extended Goldstone-boson-exchange constituent quark model
Wagenbrunn, R F; Plessas, W; Varga, K
2000-01-01
We discuss an updated version of the Goldstone-boson-exchange chiral quark model extended to include in addition to pseudoscalar meson exchanges also vector and scalar meson exchanges. The latter ingredients are viewed as effective parametrizations of multiple Goldstone-boson exchanges in baryons. The extended model allows for an accurate description of all light and strange baryon spectra and at the same time produces the right properties for deducing baryon-baryon interactions.
Barik, N; Mohanty, D K; Panda, P K; Frederico, T
2013-01-01
We have calculated the properties of nuclear matter in a self-consistent manner with quark-meson coupling mechanism incorporating structure of nucleons in vacuum through a relativistic potential model; where the dominant confining interaction for the free independent quarks inside a nucleon, is represented by a phenomenologically average potential in equally mixed scalar-vector harmonic form. Corrections due to spurious centre of mass motion as well as those due to other residual interactions such as the one gluon exchange at short distances and quark-pion coupling arising out of chiral symmetry restoration; have been considered in a perturbation manner to obtain the nucleon mass in vacuum. The nucleon-nucleon interaction in nuclear matter is then realized by introducing additional quark couplings to sigma and omega mesons through mean field approximations. The relevant parameters of the interaction are obtained self consistently while realizing the saturation properties such as the binding energy, pressure a...
Double parton distributions in Light-Front constituent quark models
Rinaldi, Matteo; Traini, Marco; Vento, Vicente
2014-01-01
Double parton distribution functions (dPDF), accessible in high energy proton-proton and proton nucleus collisions, encode information on how partons inside a proton are correlated among each other and could represent a tool to explore the 3D proton structure. In recent papers, double parton correlations have been studied in the valence quark region, by means of constituent quark models. This framework allows to understand clearly the dynamical origin of the correlations and to establish which, among the features of the results, are model independent. Recent relevant results, obtained in a relativistic light-front scheme, able to overcome some drawbacks of previous calculations, such as the poor support, will be presented. Peculiar transverse momentum correlations, generated by the correct treatment of the boosts, are obtained. The role of spin correlations will be also shown. In this covariant approach, the symmetries of the dPDFs are unambiguously reproduced. The study of the QCD evolution of the model resu...
Excited State Mass spectra and Regge trajectories of Bottom Baryons in Hypercentral quark Model
Thakkar, Kaushal; Rai, Ajay Kumar; Vinodkumar, P C
2016-01-01
We present the mass spectra of excited states of singly heavy baryons consist of a bottom quark and light quarks (u, d and s). The QCD motivated hypercentral quark model is employed for the three body description of baryons. The form of confinement potential is hyper coloumb plus power potential with potential index $\
Midrapidity inclusive densities in high energy pp collisions in additive quark model
Shabelski, Yu. M.; Shuvaev, A. G.
2016-08-01
High energy (CERN SPS and LHC) inelastic pp (pbar{p}) scattering is treated in the framework of the additive quark model together with Pomeron exchange theory. We extract the midrapidity inclusive density of the charged secondaries produced in a single quark-quark collision and investigate its energy dependence. Predictions for the π p collisions are presented.
Z(3) metastable states in Polyakov Quark Meson model
Mishra, Hiranmaya
2016-01-01
We study the existence of Z(3) metastable states in the presence of the dynamical quarks within the ambit of Polyakov quark meson (PQM) model. Within the parameters of the model, it is seen that for temperatures $T_m$ greater than the chiral transition temperature $T_c$, Z(3) metastable states exist ( $T_{m} \\sim 310$ MeV at zero chemical potential). At finite chemical potential $T_m$ is larger than the same at vanishing chemical potential. We also observe a shift of ($\\sim 5^\\circ$) in the phase of the metastable vacua at zero chemical potential. The energy density difference between true and Z(3) metastable vacua is very large in this model. This indicates a strong explicit symmetry breaking effect due to quarks in PQM model. We compare this explicit symmetry breaking in PQM model with small explicit symmetry breaking as a linear term in Polyakov loop added to the Polyakov loop potential. We also study about the possibility of domain growth in a quenched transition to QGP in relativistic heavy ion collision...
Quark Orbital Angular Momentum in the MIT Bag Model
Courtoy, A
2016-01-01
We present the results for the Generalized Transverse Momentum Distribution related to quark Orbital Angular Momentum, {\\it i.e.} $F_{14}$, in the MIT bag model. This model has been modified to include the Peierls--Yoccoz projection to restore translational invariance. Such a modification allows to fulfill more satisfactorily basic sum rules, that would otherwise be less elegantly carried out with the original version. Using the same model, we have calculated the twist-$3$ GPD that corresponds to Orbital Angular Momentum \\`a la Ji, through the Penttinen--Polyakov--Shuvaev--Strikman sum rule. Recently, a new relation between the two definitions of the quark Orbital Angular Momentum at the density level has been proposed, which we illustrate here within the model. The sum rule is fulfilled. Still within the framework of the MIT bag model, we analyze the Wandzura--Wilczek expression for the GPD of interest. The genuine quark-gluon contribution is evaluated directly thanks to the equation of motion of the bag, wh...
QCD topological susceptibility from the nonlocal chiral quark model
Nam, Seung-Il; Kao, Chung-Wen
2017-06-01
We investigate the quantum chromodynamics (QCD) topological susceptibility χ by using the semi-bosonized nonlocal chiral-quark model (SB-NLχQM) for the leading large- N c contributions. This model is based on the liquid-instanton QCD-vacuum configuration, in which SU(3) flavor symmetry is explicitly broken by the finite current-quark mass ( m u,d, m s) ≈ (5, 135) MeV. To compute χ, we derive the local topological charge-density operator Q t( x) from the effective action of SB-NLχQM. We verify that the derived expression for χ in our model satisfies the Witten- Veneziano (WV) and the Leutwyler-Smilga (LS) formulae, and the Crewther theorem in the chiral limit by construction. Once the average instanton size and the inter-instanton distance are fixed with ρ¯ = 1/3 fm and R¯ = 1 fm, respectively, all the other parameters are determined self-consistently within the model. We obtain χ = (167.67MeV)4, which is comparable with the empirical value χ = (175±5MeV)4 whereas it turns out that χ QL = (194.30MeV)4 in the quenched limit. Thus, we conclude that the value of χ will be reduced around 10 20% by the dynamical-quark contribution.
The Instanton-Dyon Liquid Model V: Twisted Light Quarks
Liu, Yizhuang; Zahed, Ismail
2016-01-01
We discuss an extension of the instanton-dyon liquid model that includes twisted light quarks in the fundamental representation with explicit $Z_{N_c}$ symmetry for the case with equal number of colors $N_c$ and flavors $N_f$. We map the model on a 3-dimensional quantum effective theory, and analyze it in the mean-field approximation. The effective potential and the vacuum chiral condensates are made explicit for $N_f=N_c=2, 3$. The low temperature phase is center symmetric but breaks spontaneously flavor symmetry with $N_f-1$ massless pions. The high temperature phase breaks center symmetry but supports finite and unequal quark condensates.
Supersymmetry and Light Quark Masses in a Realistic Superstring Model
Halyo, E
1994-01-01
We examine the light quark masses in a standard--like superstring model in the four dimensional free fermionic formulation. We find that the supersymmetry constraints in the observable and hidden sectors eliminate all large contributions to $m_u$ and $m_d$ and force them to be much smaller than the other quark masses. The requirement for an acceptable Higgs doublet spectrum results in $m_u<
KN Phase Shifts in Chiral SU（3） Quark Model
Institute of Scientific and Technical Information of China (English)
HUANGFei; ZHANGZong-Ye; YUYou-Wen
2004-01-01
The isospin I = 0 and I = 1 kaon-nucleon S and P partial waves phase shifts have been studied in the chiral SU(3) quark model by solving a resonating group method equation. When the parameters of the chiral fields are taken in a reasonable region, the numerical results of S-wave are in good agreement with the experimental data, and the P-wave phase shifts can also be explained qualitatively by the calculation of only central force considered.
Semileptonic Decays of Heavy Omega Baryons in a Quark Model
Energy Technology Data Exchange (ETDEWEB)
Muslema Pervin; Winston Roberts; Simon Capstick
2006-03-24
The semileptonic decays of {Omega}{sub c} and {Omega}{sub b} are treated in the framework of a constituent quark model developed in a previous paper on the semileptonic decays of heavy {Lambda} baryons. Analytic results for the form factors for the decays to ground states and a number of excited states are evaluated. For {Omega}{sub b} to {Omega}{sub 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 {Lambda}{sub c}{sup +} {yields} {Lambda}e{sup +}{nu} rate, with wave functions expanded in both harmonic oscillator and Sturmian bases. Decay rates of {Omega}{sub b} to pairs of ground and excited {Omega}{sub 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}{sub Q} vary minimally within the models we use. We obtain an average value of (84 {+-} 2%) for the fraction of {Omega}{sub c} {yields} {Xi}{sup (*)} decays to ground states, and 91% for the fraction of {Omega}{sub c} {yields} {Omega}{sup (*)} decays to the ground state {Omega}. The elastic fraction of {Omega}{sub b} {yields} {Omega}{sub c} ranges from about 50% calculated with the two harmonic-oscillator models, to about 67% calculated with the two Sturmian models.
Spin Structure Functions in a Covariant Spectator Quark Model
Energy Technology Data Exchange (ETDEWEB)
G. Ramalho, Franz Gross and M. T. Peña
2010-12-01
We apply the covariant spectator quark–diquark model, already probed in the description of the nucleon elastic form factors, to the calculation of the deep inelastic scattering (DIS) spin-independent and spin-dependent structure functions of the nucleon. The nucleon wave function is given by a combination of quark–diquark orbital states, corresponding to S, D and P-waves. A simple form for the quark distribution function associated to the P and D waves is tested.
Improved quark coalescence for a multi-phase transport model
He, Yuncun; Lin, Zi-Wei
2017-07-01
The string melting version of a multi-phase transport model is often applied to high-energy heavy-ion collisions since the dense matter thus formed is expected to be in parton degrees of freedom. In this work we improve its quark coalescence component, which describes the hadronization of the partonic matter to a hadronic matter. We removed the previous constraint that forced the numbers of mesons, baryons, and antibaryons in an event to be separately conserved through the quark coalescence process. A quark now could form either a meson or a baryon depending on the distance to its coalescence partner(s). We then compare results from the improved model with the experimental data on hadron d N /d y ,pT spectra, and v2 in heavy-ion collisions from √{s NN}=62.4 GeV to 5.02 TeV. We show that, besides being able to describe these observables for low-pTpions and kaons, the improved model also better describes the low-p T baryon observables in general, especially the baryon p T spectra and antibaryon-to-baryon ratios for multistrange baryons.
Models of quark-hadron matter and compact stars
Energy Technology Data Exchange (ETDEWEB)
Schramm, S.; Steinheimer, J. [FIAS, Ruth-Moufang-Str. 1, D-60438 Frankfurt (Germany); Dexheimer, V. [Department of Physics, Kent State University, Kent OH 44242 (United States); Negreiros, R. [Instituto de Fisica, Universidade Federal Fluminense, Niteroi (Brazil)
2016-01-22
Phenomenological approaches to Quantum Chromodynamics covering the whole region of low and high temperatures and/or densities must address the problem that the effective degrees of freedom change from hadrons to quarks and gluons. We approach this task with a unified description of hadronic and quark matter allowing for cross-over as well as first or second-order phase transitions. As a further benefit of such an approach, a quantitatively satisfactory description of nuclear ground state matter as well as nuclear and hypernuclear properties can be achieved. We apply this model to neutron stars and consider potential constraints on star properties arising from lattice gauge results in relation with the observation of 2 solar mass stars.
Radiative leptonic Bc decay in the relativistic independent quark model
Barik, N.; Naimuddin, Sk.; Dash, P. C.; Kar, Susmita
2008-12-01
The radiative leptonic decay Bc-→μ-ν¯μγ is analyzed in its leading order in a relativistic independent quark model based on a confining potential in an equally mixed scalar-vector harmonic form. The branching ratio for this decay in the vanishing lepton mass limit is obtained as Br(Bc→μνμγ)=6.83×10-5, which includes the contributions of the internal bremsstrahlung and structure-dependent diagrams at the level of the quark constituents. The contributions of the bremsstrahlung and the structure-dependent diagrams, as well as their additive interference parts, are compared and found to be of the same order of magnitude. Finally, the predicted photon energy spectrum is observed here to be almost symmetrical about the peak value of the photon energy at Ẽγ≃(MBc)/(4), which may be quite accessible experimentally at LHC in near future.
Characteristics of the chiral phase transition in nonlocal quark models
Dumm, D G
2004-01-01
The characteristics of the chiral phase transition are analyzed within the framework of chiral quark models with nonlocal interactions in the mean field approximation (MFA). In the chiral limit, we show that there is a region of low values of the chemical potential in which the transition is a second order one. In that region, it is possible to perform a Landau expansion and determine the critical exponents which, as expected, turn out to be the MFA ones. Our analysis also allows to obtain semi-analytical expressions for the transition curve and the location of the tricritical point. For the case of finite current quark masses, we study the behavior of various thermodynamical and chiral response functions across the phase transition.
Chiral Lagrangian and chiral quark model from confinement in QCD
Simonov, Yu A
2015-01-01
The effective chiral Lagrangian in both nonlocal form $L_{ECCL}$ and standard local form $L_{ECL}$ are derived in QCD using the confining kernel, obtained in the vacuum correlator formalism. As a result all coefficients of $L_{ECL}$ can be computed via $q\\bar q$ Green's functions. In the $p^2$ order of $L_{ECL}$ one obtains GOR relations and quark decay constants $f_a$ are calculated $a=1,...8$, while in the $p^4$ order the coefficients $L_1, L_2, L_3,L_4, L_5, L_6$ are obtained in good agreement with the values given by data. The chiral quark model is shown to be a simple consequence of $L_{ECCL}$ with defined coefficients. It is demonstrated that $L_{ECCL}$ gives an extension of the limiting low-energy Lagrangian $L_{ECL}$ to arbitrary momenta.
Λc semileptonic decays in a quark model
Hussain, Md Mozammel; Roberts, Winston
2017-03-01
Hadronic form factors for semileptonic decay of the Λc are calculated in a nonrelativistic quark model. The full quark model wave functions are employed to numerically calculate the form factors to all relevant orders in (1 /mc, 1 /ms). The form factors obtained satisfy relationships expected from the heavy quark effective theory (HQET). The differential decay rates and branching fractions are calculated for transitions to the ground state and a number of excited states of Λ . The branching fraction of the semileptonic decay width to the total width of Λc has been calculated and compared with other theoretical estimates and experimental results. The branching fractions for Λc→Λ*l+νl→Σ π l+νl and Λc→Λ*l+νl→N K ¯ l+νl are also calculated. Apart from decays to the ground state Λ (1115 ) , it is found that decays through the Λ (1405 ) provide a significant portion of the branching fraction Λc→Xsl νl . A new estimate for f =B (Λc+→Λ l+νl)/B (Λc+→Xsl+νl) is obtained.
Phase structure of cold magnetized quark matter within the SU(3) NJL model
Grunfeld, A G; Pinto, M B; Scoccola, N N
2014-01-01
The possible different phases of cold quark matter in the presence of a finite magnetic field and chemical potential are obtained within the SU(3) NJL model for two parameter sets often used in the literature. Although the general pattern is the same in both cases, the number of intermediate phases is parameter dependent. The chiral susceptibilities, as usually defined, are different not only for the s-quark as compared with the two light quarks, but also for the u and d-quarks, yielding non identical crossover lines for the light quark sector.
Hyperon stars in a modified quark meson coupling model
Mishra, R. N.; Sahoo, H. S.; Panda, P. K.; Barik, N.; Frederico, T.
2016-09-01
We determine the equation of state (EOS) of nuclear matter with the inclusion of hyperons in a self-consistent manner by using a modified quark meson coupling model where the confining interaction for quarks inside a baryon is represented by a phenomenological average potential in an equally mixed scalar-vector harmonic form. The hadron-hadron interaction in nuclear matter is then realized by introducing additional quark couplings to σ ,ω , and ρ mesons through mean-field approximations. The effect of a nonlinear ω -ρ term on the EOS is studied. The hyperon couplings are fixed from the optical potential values and the mass-radius curve is determined satisfying the maximum mass constraint of 2 M⊙ for neutron stars, as determined in recent measurements of the pulsar PSR J0348+0432. We also observe that there is no significant advantage of introducing the nonlinear ω -ρ term in the context of obtaining the star mass constraint in the present set of parametrizations.
Hyperon star in a modified quark meson coupling model
Mishra, R N; Panda, P K; Barik, N; Frederico, T
2016-01-01
We determine the equation of state (EOS) of nuclear matter with the inclusion of hyperons in a self-consistent manner by using a Modified Quark Meson Coupling Model (MQMC) where the confining interaction for quarks inside a baryon is represented by a phenomenological average potential in an equally mixed scalar-vector harmonic form. The hadron-hadron interaction in nuclear matter is then realized by introducing additional quark couplings to $\\sigma$, $\\omega$, and $\\rho$ mesons through mean-field approximations. The effect of a nonlinear $\\omega$-$\\rho$ term on the equation of state is studied. The hyperon couplings are fixed from the optical potential values and the mass-radius curve is determined satisfying the maximum mass constraint of $2$~M$_{\\odot}$ for neutron stars, as determined in recent measurements of the pulsar PSR J0348+0432. We also observe that there is no significant advantage of introducing the nonlinear $\\omega$-$\\rho$ term in the context of obtaining the star mass constraint in the present...
A Euclidean bridge to the relativistic constituent quark model
Hobbs, Timothy; Alberg, Mary; Miller, Gerald
2017-01-01
We explore the potential of a Euclidean constituent quark model (ECQM) to bridge the lingering gap between Euclidean and Minkowski field theories in studies of nucleon structure. Specifically, we develop our ECQM using a simplified quark-scalar diquark picture of the nucleon as a first calculation. Our treatment in Euclidean space necessitates a hyperspherical formalism involving polynomial expansions of diquark propagators in order to marry our ECQM with results from Bethe-Salpeter Equation (BSE) analyses. From this framework, we define and compute a new quantity - a Euclidean density function (EDF) - an object that characterizes the nucleon's various charge distributions as functions of the quark's Euclidean momentum. Applying this technology and incorporating information from BSE analyses, we find the quenched dressing effect on the proton's axial-singlet charge to be small in magnitude and consistent with zero, while use of recent determinations of unquenched BSEs results in a large suppression. The substantial effect we obtain for the impact on the axial-singlet charge of the unquenched dressed vertex compared to the quenched demands further investigation. Work supported by DOE grant DE-FG02-97ER-41014 and NSF Grant No. 1516105.
Strong interaction of hadrons in quark cluster model
Directory of Open Access Journals (Sweden)
Arezu Jahanshir
2015-09-01
Full Text Available The theoretical information on the hadrons interactions according to the basis investigation of the multiple scattering process theory is described. As we know multi-particle reactions on the hadrons targets are attracting a great attention nowadays. To survey strong interaction of jet particles with quarks that are inside hadrons (Baryons,mesons, exotic baryons(Penta-quarks, exotic mesons(Tetra-quarks, we can use the estimate called high energy approximation (Eikonal or Glauber approximation theory that known very well in nuclear physics. This estimate describes collision and interactions of jet particles with quarks and scattering from multi-focus hadrons like diffraction phenomenon in optics. Glauber multiple scattering process theory may apply in analyzing elastic and inelastic collision of hadrons in a range of high energy levels. In elastic collision, scattering amplitude is equal to total ranges of multiple collisions inside the hadrons. It’s possible to express Glauber multiple scattering factor in a form of mathematic series. So that each elements shows the number of occurred scattering inside the hadrons. Determination of scattering amplitude by the high energy approximation depends on elected primary coming wave function of the shot particle and function of out coming wave from the target nucleus. Therefore it’s not so hard to determine scattering amplitude. The main purpose of this paper is to show how to determine mathematical formula for differential cross section of jet particles in high energy levels with a hadrons in cluster model (qq, qq (Quarkonium-Quarkonium cluster.
Successes and failures of the constituent quark model
Energy Technology Data Exchange (ETDEWEB)
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.
Higher bottomonia in the unquenched quark model
Directory of Open Access Journals (Sweden)
Ferretti J.
2014-06-01
Full Text Available We show our results for the bottomonium spectrum with self energy corrections, due to the coupling to the meson-meson continuum. We also discuss our results for the open bottom strong decays of higher bottomonia in the 3P0 pair-creation model.
Generalized SU(3) Nambu-Jona-Lasinio model. Pt. 2; From current to constituent quarks
Energy Technology Data Exchange (ETDEWEB)
Vogl, U.; Lutz, M.; Klimt, S.; Weise, W. (Regensburg Univ. (Germany, F.R.). Inst. fuer Physik 1 - Theoretische Physik)
1990-10-08
We investigate the properties of constituent quarks, i.e. quarks dressed by their strong interactions, in a generalized Nambu-Jona-Lasinio model with N{sub f}=3 flavours. In the Hartree-Fock approximation, the step from structureless current quarks to massive constituent quarks is made through dynamical mass generation which implies spontaneous chiral symmetry breaking. We study, in particular, the quark scalar, vector and axial vector currents within this framework. We demonstrate that, a low energy and momentum transfers, single valence quarks are strongly screened by quark-antiquark polarization effects. For the electromagnetic currents, we recover relationships familiar from the vector meson dominance model. For the axial current, screening by J{sup {pi}}=1{sup +} quark-antiquark modes leads to an effective quark axial vector constant g{sub A}<1 which satisfies the Goldberger-Treiman relation at the quark level. The spin content of the proton is also discussed in this framework. We calculate quark magnetic moments and electromagnetic form factors and discuss their related sizes. (orig.).
Soft Matrix Elements in Non-local Chiral Quark Model
Kotko, Piotr
2009-01-01
Using non-local chiral quark model and currents satisfying Ward-Takahashi identities we analyze Distribution Amplitudes (DA) of photon and pion-to-photon Transition Distribution Amplitudes (TDA) in the low energy regime. Photon DA's are calculated analytically up to twist-4 and reveal several interesting features of photon structure. TDA's calculated in the present model satisfy polynomiality condition. Normalization of vector TDA is fixed by the axial anomaly. We also compute relevant form factors and compare them with existing data. Axial form factor turns out to be much lower then the vector one, what indeed is seen in the experimental data.
Warm stellar matter within the quark-meson-coupling model
Panda, P. K.; Providência, C.; Menezes, D. P.
2010-10-01
In the present article, we investigate stellar matter obtained within the quark-meson-coupling (QMC) model for fixed temperature and with the entropy of the order of 1 or 2 Boltzmann units per baryon for neutrino-free matter and matter with trapped neutrinos. A new prescription for the calculation of the baryon effective masses in terms of the free energy is used. Comparing the results of the present work with those obtained from the nonlinear Walecka model, smaller strangeness and neutrino fractions are predicted within QMC. As a consequence, QMC has a smaller window of metastability for conversion into a low-mass blackhole during cooling.
Nuclear Transparency in a Relativistic Quark Model
Iwama, T; Yazaki, K; Iwama, Tetsu; Kohama, Akihisa; Yazaki, Koichi
1998-01-01
We examine the nuclear transparency for the quasi-elastic ($e, e'p$) process at large momentum transfers in a relativistic quantum-mechanical model for the internal structure of the proton, using a relativistic harmonic oscillator model. A proton in a nuclear target is struck by the incident electron and then propagates through the residual nucleus suffering from soft interactions with other nucleons. We call the proton "dynamical" when we take into account of internal excitations, and "inert" when we freeze it to the ground state. When the dynamical proton is struck with a hard (large-momentum transfer) interaction, it shrinks, i.e., small-sized configuration dominates the process. It then travels through nuclear medium as a time-dependent mixture of intrinsic excited states and thus changing its size. Its absorption due to the soft interactions with nuclear medium depends on its transverse-size. Since the nuclear transparency is a measure of the absorption strength, we calculate it in our model for the dyna...
Barik, N.; Mishra, R. N.; Mohanty, D. K.; Panda, P. K.; Frederico, T.
2013-07-01
We have calculated the properties of nuclear matter in a self-consistent manner with a quark-meson coupling mechanism incorporating the structure of nucleons in vacuum through a relativistic potential model; where the dominant confining interaction for the free independent quarks inside a nucleon is represented by a phenomenologically average potential in equally mixed scalar-vector harmonic form. Corrections due to spurious center of mass motion as well as those due to other residual interactions, such as the one gluon exchange at short distances and quark-pion coupling arising out of chiral symmetry restoration, have been considered in a perturbative manner to obtain the nucleon mass in vacuum. The nucleon-nucleon interaction in nuclear matter is then realized by introducing additional quark couplings to σ and ω mesons through mean field approximations. The relevant parameters of the interaction are obtained self-consistently while realizing the saturation properties such as the binding energy, pressure, and compressibility of the nuclear matter. We also discuss some implications of chiral symmetry in nuclear matter along with the nucleon and nuclear σ term and the sensitivity of nuclear matter binding energy with variations in the light quark mass.
Multiplicity fluctuation and correlation of identified baryons in quark combination model
Song, Jun; Wang, Rui-qin; Shao, Feng-lan
2016-01-01
The dynamical fluctuation and correlation of multiplicity distributions of identified baryons and antibaryons produced by the hadronization of the bulk quark system are systematically studied in quark combination model. Starting from the most basic dynamics of quark combination which are necessary for multiplicity study, we analyze moments (variance, skewness and kurtosis) of inclusive multiplicity distribution of identified baryons, two-baryon multiplicity correlations, and baryon-antibaryon multiplicity correlations after the hadronization of quark system with given quark number and antiquark number. We obtain a series of interesting findings, e.g., binomial behavior of multiplicity moments, coincide flavor dependent two-baryon correlation and universal baryon-antibaryon correlation, which can be regarded as general features of quark combination. We further take into account correlations and fluctuations of quark numbers before hadronization to study their influence on multiple production of baryons and ant...
Parton Distribution in Pseudoscalar Mesons with a Light-Front Constituent Quark Model
de Melo, J P B C; Tsushima, Kazuo
2015-01-01
We compute the distribution amplitudes of the pion and kaon in the light-front constituent quark model with the symmetric quark-bound state vertex function. In the calculation we explicitly include the flavor-SU(3) symmetry breaking effect in terms of the constituent quark masses of the up (down) and strange quarks. To calculate the kaon parton distribution functions~(PDFs), we use both the conditions in the light-cone wave function, i.e., when $\\bar{s}$ quark is on-shell, and when $u$ quark is on-shell, and make a comparison between them. The kaon PDFs calculated in the two different conditions clearly show asymmetric behaviour due to the flavor SU(3)-symmetry breaking implemented by the quark masses.
Magnetic Moments of Baryons containing all heavy quarks in Quark-Diquark Model
Thakkar, Kaushal; Vinodkumar, P C
2016-01-01
The triply heavy flavour baryons are studied using the Quark-diquark description of the three-body system. The confinement potential for present study of triply heavy flavour baryons is assumed as coulomb plus power potential with power index $\
Dynamical quark loop light-by-light contribution to muon g-2 within the nonlocal chiral quark model
Energy Technology Data Exchange (ETDEWEB)
Dorokhov, A.E. [Bogoliubov Laboratory of Theoretical Physics, JINR, Dubna (Russian Federation); M.V. Lomonosov Moscow State University, N.N. Bogoliubov Institute of Theoretical Problems of Microworld, Moscow (Russian Federation); Radzhabov, A.E. [Institute for System Dynamics and Control Theory SB RAS, Irkutsk (Russian Federation); Zhevlakov, A.S. [Institute for System Dynamics and Control Theory SB RAS, Irkutsk (Russian Federation); Tomsk State University, Department of Physics, Tomsk (Russian Federation)
2015-09-15
The hadronic corrections to the muon anomalous magnetic moment a{sub μ}, due to the gauge-invariant set of diagrams with dynamical quark loop light-by-light scattering insertions, are calculated in the framework of the nonlocal chiral quark model. These results complete calculations of all hadronic light-by-light scattering contributions to a{sub μ} in the leading order in the 1/N{sub c} expansion. The result for the quark loop contribution is a{sub μ}{sup HLbL,Loop} = (11.0 ± 0.9) @ x 10{sup -10}, and the total result is a{sub μ}{sup HLbL,NχQM} = (16.8 ± 1.2) @ x 10{sup -10}. (orig.)
Indian Academy of Sciences (India)
P. K. AGRAWAL; D. D. PAWAR
2017-03-01
We studied plane symmetric cosmological model in the presence of quark and strange quark matter with the help of ${f(R, T)}$ theory. To decipher solutions of plane symmetric space-time, we used power law relation between scale factor and deceleration parameter. We considered the special law of variation of Hubble’s parameter proposed by Berman (Nuovo Cimento B74, 182, 1983) which yields constant deceleration parameter. We also discussed the physical behavior of the solutions by using some physical parameters.
Δ - Δ resonance in the nonrelativistic quark model
Cvetič, M.; Golli, B.; Mankoč-Borštnik, N.; Rosina, M.
1980-06-01
The Δ - Δ resonance is treated in the nonrelativistic quark model. The trial wave function is a colour singlet including N-N, Δ - Δ and coloured baryon channels. The effective Δ - Δ potential is repulsive at all distances for T=0, S=1, L=0,2,4 while for T=3, S=0, L=0 and T=0, S=3, L=0 it has a minimum. The GCM calculation gives for the latter state the binding emergy ∼ -40 MeV.
Color symmetrical superconductivity in a schematic nuclear quark model
DEFF Research Database (Denmark)
Bohr, Henrik; Providencia, C.; da Providencia, J.
2010-01-01
In this letter, a novel BCS-type formalism is constructed in the framework of a schematic QCD inspired quark model, having in mind the description of color symmetrical superconducting states. In the usual approach to color superconductivity, the pairing correlations affect only the quasi......-particle states of two colors, the single-particle states of the third color remaining unaffected by the pairing correlations. In the theory of color symmetrical superconductivity here proposed, the pairing correlations affect symmetrically the quasi-particle states of the three colors and vanishing net color...
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
QCD topological susceptibility from the nonlocal chiral quark model
Nam, Seung-il
2016-01-01
We investigate the QCD topological susceptibility $\\chi_t$ by using the nonlocal chiral quark model (NL$\\chi$QM). This model is based on the liquid instanton QCD-vacuum configuration in which $\\mathrm{SU}(3)$ flavor symmetry is explicitly broken by the current quark mass $(m_{u,d},m_s)\\approx(5,135)$ MeV. To compute $\\chi_t$, the local topological charge density operator $Q_t(x)$ is derived from the effective partition function of NL$\\chi$QM. We take into account the contributions from the leading-order (LO) ones $\\sim\\mathcal{O}(N_c)$ in the $1/N_c$ expansion. We also verify that the analytical expression of $\\chi_t$ in NL$\\chi$QM satisfy the Witten-Veneziano (WV) and the Leutwyler-Smilga (LS) formulae. Once the average instanton size and inter-instanton distance are fixed with $\\bar{\\rho}=1/3$ fm and $\\bar{R}=1$ fm, respectively, all the associated model parameters are all determined self-consistently within the model, including the $\\eta$ and $\\eta'$ weak decay constants. We obtain the results such as $F_{...
A chiral quark model for meson electro-production in the S11 partial wave
Golli, Bojan
2011-01-01
We calculate the meson scattering and electroproduction amplitudes in the S11 partial wave in a coupled-channel approach that incorporates quasi-bound quark-model states. Using the quark wave functions and the quark-meson interaction from the Cloudy Bag Model, we obtain consistent predictions for the partial widths of the N(1535) and the N(1650) resonances as well as for the pion, eta and kaon electroproduction amplitudes. Our model suggests that the N(1535) resonance is dominantly a genuine three-quark state rather than a quasi-bound state of mesons and baryons.
Phase Structure in a Quark Mass Density-and-Temperature-Dependent Model
Institute of Scientific and Technical Information of China (English)
WEN Xin-Jian; PENG Guang-Xiong; SHEN Peng-Nian
2007-01-01
The phase diagram of bulk quark matter in equilibrium with a finite hadronic gas is studied. Different from previous investigations, we treat the quark phase with the quark rnass density-and-temperature-dependent model to take the strong quark interaction into account, while the hadron phase is treated by hard core repulsion factor. It is found that the phase diagram in this model is, in several aspects, different from those in the conventional MIT bag model, especially at high temperature. The new phase diagram also has strong effects on the mass-radius relation of compact hybrid stars.
Axial form factor of the nucleon in the perturbative chiral quark model
Khosonthongkee, K; Faessler, Amand; Gutsche, T; Lyubovitskij, V E; Pumsa-ard, K; Yan, Y
2004-01-01
We apply the perturbative chiral quark model (PCQM) at one loop to analyze the axial form factor of the nucleon. This chiral quark model is based on an effective Lagrangian, where baryons are described by relativistic valence quarks and a perturbative cloud of Goldstone bosons as dictated by chiral symmetry. We apply the formalism to obtain analytical expressions for the axial form factor of the nucleon, which is given in terms of fundamental parameters of low-energy pion-nucleon physics (weak pion decay constant, strong pion-nucleon form factor) and of only one model parameter (radius of the nucleonic three-quark core).
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.
Finite-temperature corrections in the dilated chiral quark model
Kim, Y; Rho, M; Kim, Youngman; Lee, Hyun Kyu; Rho, Mannque
1995-01-01
We calculate the finite-temperature corrections in the dilated chiral quark model using the effective potential formalism. Assuming that the dilaton limit is applicable at some short length scale, we interpret the results to represent the behavior of hadrons in dense {\\it and} hot matter. We obtain the scaling law, \\frac{f_{\\pi}(T)}{f_{\\pi}} = \\frac{m_Q (T)}{m_Q} \\simeq \\frac{m_{\\sigma}(T)}{m_{\\sigma}} while we argue, using PCAC, that pion mass does not scale within the temperature range involved in our Lagrangian. It is found that the hadron masses and the pion decay constant drop faster with temperature in the dilated chiral quark model than in the conventional linear sigma model that does not take into account the QCD scale anomaly. We attribute the difference in scaling in heat bath to the effect of baryonic medium on thermal properties of the hadrons. Our finding would imply that the AGS experiments (dense {\\it and} hot matter) and the RHIC experiments (hot and dilute matter) will ``see" different hadron...
The theory and phenomenology of coloured quark models
Close, F E
1975-01-01
A general introduction to coloured quark models is given and their phenomenology is described with particular reference to the new particles. It is shown that there are essentially three types of colour models with colour excitation when the colour group is SU(3)- Han-Nambu, Greenberg and a model which has the same charges as that of Tati and which can be thought of as the Gell-Mann colour scheme with excitation of the colour degrees of freedom. Particular attention is paid to the four problems of colour models for psi phenomenology-the radiative decays, the G parity conservation, the lack of deep inelastic threshold phenomena and the apparent discovery of dileptons at SPEAR. (40 refs).
Weak leptonic decay of light and heavy pseudoscalar mesons in an independent quark model
Energy Technology Data Exchange (ETDEWEB)
Barik, N.; Dash, P.C. (Department of Physics, Utkal University, Bhubaneswar-751004 (India))
1993-04-01
Weak leptonic decays of light and heavy pseudoscalar mesons are studied in a field-theoretic framework based on the independent quark model with a scalar-vector harmonic potential. Defining the quark-antiquark momentum distribution amplitude obtainable from the bound quark eigenmodes of the model with the assumption of a strong correlation between quark-antiquark momenta inside the decaying meson in its rest frame, we derive the partial decay width with correct kinematical factors from which we extract an expression for the pseudoscalar decay constants [ital f][sub [ital M
Chen, X B; Chen, X S; Wang, F
2001-07-02
We perform a one-loop calculation of the strange quark polarization (Deltas) of the nucleon in an SU(3) chiral potential model. We find that if the intermediate quark excited states are summed over in a proper way, i.e., summed up to a given energy instead of given radial and orbital quantum numbers, Deltas turns out to be almost independent of all the model parameters: quark masses and potential strengths. The contribution from the quark-antiquark pair creation and annihilation " Z" diagrams is found to be significant. Our numerical results agree quite reasonably with experiments and lattice QCD calculations.
Nonperturbative models of quark stars in $f(R)$ gravity
Astashenok, A V; Odintsov, S D
2014-01-01
Quark star models with realistic equation of state in nonperturbative $f(R)$ gravity are considered. The mass-radius relation for $f(R)=R+\\alpha R^2$ model is obtained. Considering scalar curvature $R$ as an independent function, one can find out, for each value of central density, the unique value of central curvature for which one has solutions with the required asymptotic $R\\rightarrow 0$ for $r\\rightarrow\\infty$. In another words, one needs a fine-tuning for $R$ to achieve quark stars in $f(R)$ gravity. We consider also the analogue description in corresponding scalar-tensor gravity. The fine-tuning on $R$ is equivalent to the fine-tuning on the scalar field $\\phi$ in this description. For distant observers, the gravitational mass of the star increases with increasing $\\alpha$ ($\\alpha>0$) but the interpretation of this fact depends on frame where we work. Considering directly $f(R)$ gravity, one can say that increasing of mass occurs by the "gravitational sphere" outside the star with some "effective mas...
Finite Nuclei in the Quark-Meson Coupling Model.
Stone, J R; Guichon, P A M; Reinhard, P G; Thomas, A W
2016-03-04
We report the first use of the effective quark-meson coupling (QMC) energy density functional (EDF), derived from a quark model of hadron structure, to study a broad range of ground state properties of even-even nuclei across the periodic table in the nonrelativistic Hartree-Fock+BCS framework. The novelty of the QMC model is that the nuclear medium effects are treated through modification of the internal structure of the nucleon. The density dependence is microscopically derived and the spin-orbit term arises naturally. The QMC EDF depends on a single set of four adjustable parameters having a clear physics basis. When applied to diverse ground state data the QMC EDF already produces, in its present simple form, overall agreement with experiment of a quality comparable to a representative Skyrme EDF. There exist, however, multiple Skyrme parameter sets, frequently tailored to describe selected nuclear phenomena. The QMC EDF set of fewer parameters, derived in this work, is not open to such variation, chosen set being applied, without adjustment, to both the properties of finite nuclei and nuclear matter.
Nonperturbative models of quark stars in f(R gravity
Directory of Open Access Journals (Sweden)
Artyom V. Astashenok
2015-03-01
Full Text Available Quark star models with realistic equation of state in nonperturbative f(R gravity are considered. The mass-radius relation for f(R=R+αR2 model is obtained. Considering scalar curvature R as an independent function, one can find out, for each value of central density, the unique value of central curvature for which one has solutions with the required asymptotic R→0 for r→∞. In other words, one needs a fine-tuning for R to achieve quark stars in f(R gravity. We consider also the analogue description in corresponding scalar-tensor gravity. The fine-tuning on R is equivalent to the fine-tuning on the scalar field ϕ in this description. For distant observers, the gravitational mass of the star increases with increasing α (α>0 but the interpretation of this fact depends on frame where we work. Considering directly f(R gravity, one can say that increasing of mass occurs by the “gravitational sphere” outside the star with some “effective mass”. On the other hand, in conformal scalar-tensor theory, we also have a dilaton sphere (or “disphere” outside the star but its contribution to gravitational mass for distant observer is negligible. We show that it is possible to discriminate modified theories of gravity from General Relativity due to the gravitational redshift of the thermal spectrum emerging from the surface of the star.
The controversy about "1/m_Q duality violation" ; a quark model point of view
Le Yaouanc, A; Morénas, V; Oliver, L; Pène, O; Raynal, J C; Yaouanc, Alain Le; Melikhov, Dimitri; Morenas, Vincent; Oliver, Lluis; Pene, Olivier; Raynal, Jean-Claude
2006-01-01
A detailed discussion based on exact calculations, possible in the non relativistic quark model, is given to show that there is no 1/m_Q term in the heavy quark expansion of totally integrated semileptonic decay rates. More generally, it is shown that OPE holds with very few terms in the expansion, at least in the harmonic oscillator model.
Cao, Shanshan; Qin, Guang-You; Wang, Xin-Nian
2016-01-01
A Linearized Boltzmann Transport (LBT) model coupled with hydrodynamical background is established to describe the evolution of jet shower partons and medium excitations in high energy heavy-ion collisions. We extend the LBT model to include both elastic and inelastic processes for light and heavy partons in the quark-gluon plasma. A hybrid model of fragmentation and coalescence is developed for the hadronization of heavy quarks. Within this framework, we investigate how heavy flavor observables depend on various ingredients, such as different energy loss and hadronization mechanisms, the momentum and temperature dependences of the transport coefficients, and the radial flow of the expanding fireball. Our model calculations show good descriptions of $D$ meson suppression and elliptic flow observed at the LHC and RHIC. The prediction for the Pb-Pb collisions at $\\sqrt{s_\\mathrm{NN}}$=5.02 TeV is provided.
Semileptonic ( → ) decay in a ﬁeld theoretic quark model
Indian Academy of Sciences (India)
R K Das; A R Panda; R K Sahoo; M R Swain
2002-03-01
The semileptonic decay width of heavy baryons such as ( → ) has been estimated in the framework of a nonrelativistic ﬁeld theoretic quark model where four component quark ﬁeld operators along with a harmonic oscillator wave function are used to describe translationally invariant hadronic states. The present estimation does not make an explicit use of heavy quark symmetry and has a reasonable agreement with the experimentally measured decay width, polarisation ratio and form factors with the harmonic oscillator radii and quark momentum distribution inside the hadron as free parameters.
Interactions between Octet Baryons in the SU_6 Quark model
Fujiwara, Y; Nakamoto, C; Suzuki, Y
2001-01-01
The baryon-baryon interactions for the complete baryon octet (B_8) are investigated in a unified framework of the resonating-group method, in which the spin-flavor SU_6 quark-model wave functions are employed. Model parameters are determined to reproduce properties of the nucleon-nucleon system and the low-energy cross section data for the hyperon-nucleon interaction. We then proceed to explore B_8 B_8 interactions in the strangeness S=-2, -3 and -4 sectors. The S-wave phase-shift behavior and total cross sections are systematically understood by 1) the spin-flavor SU_6 symmetry, 2) the special role of the pion exchange, and 3) the flavor symmetry breaking.
Selected problems of baryons spectroscopy: chiral soliton versus quark models
Kopeliovich, Vladimir B
2008-01-01
Inconsistency between rigid rotator and bound state models at arbitrary number of colors, rigid rotator -- soft rotator dilemma and some other problems of baryon spectroscopy are discussed in the framework of the chiral soliton approach (CSA). Consequences of the comparison of CSA results with simple quark models are considered and the $1/N_c$ expansion for the effective strange antiquark mass is presented, as it follows from the CSA. Strong dependence of the effective strange antiquark mass on the SU(3) multiplet is required to fit the CSA predictions. The difference of `good' and `bad' diquark masses, which is about 100 Mev, is in reasonable agreement with other estimates. Multibaryons (hypernuclei) with strangeness are described and some states of interest are predicted within CSA as well.
Transverse-momentum dependent parton distribution functions beyond leading twist in quark models
Lorcé, C; Schweitzer, P
2014-01-01
Higher-twist transverse momentum dependent parton distribution functions (TMDs) are a valuable probe of the quark-gluon dynamics in the nucleon, and play a vital role for the explanation of sizable azimuthal asymmetries in hadron production from unpolarized and polarized deep-inelastic lepton-nucleon scattering observed in experiments at CERN, DESY and Jefferson Lab. The associated observables are challenging to interpret, and still await a complete theoretical explanation, which makes guidance from models valuable. In this work we establish the formalism to describe unpolarized higher-twist TMDs in the light-front framework based on a Fock-space expansion of the nucleon state in terms of free on-shell parton states. We derive general expressions and present numerical results in a practical realization of this picture provided by the light-front constituent quark model. We review several other popular quark model approaches including free quark ensemble, bag, spectator and chiral quark-soliton model.
Renormalizability of a quark-gluon model with soft BRST breaking in the infrared region
Baulieu, L; Gomez, A J; Lemes, V E R; Sobreiro, R F; Sorella, S P
2010-01-01
We prove the renormalizability of a quark-gluon model with a soft breaking of the BRST symmetry, which accounts for the modification of the large distance behavior of the quark and gluon correlation functions. The proof is valid to all orders of perturbation theory, by making use of softly broken Ward identities.
Doubly heavy baryons in a quark model with AdS/QCD inspired potential
Giannuzzi, Floriana
2009-01-01
The spectrum of doubly heavy baryons, hadrons made up of two heavy quarks and one light quark, is computed through a potential model with relativistic kinematics. The expression for the $Q\\bar Q$ potential comes from the AdS/QCD correspondence.
Study of the heavy molecular states in the quark model with meson exchange interaction
Institute of Scientific and Technical Information of China (English)
YU Si-Hai; WANG Bao-Kai; CHEN Xiao-Lin; DENG Wei-Zhen
2012-01-01
Some charmonium-like resonances such as X(3872) can be interpreted as possible D(*)(D)(*) molecular states.Within the quark model,we study the structure of such molecular states and the similar B(*)(B)(*)molecular states by taking into account the light meson exchange (π,η,ρ,ω and σ) between two light quarks from different mesons.
The Strange Magnetic Moment of the Proton in the Chiral Quark Model
1998-01-01
The strange magnetic moment of the proton is small in the chiral quark model, because of a near cancellation between the quantum fluctuations that involve kaons and $s$-quarks and loops that involve radiative transitions between strange vector mesons and kaons.
Nucleon parton distributions in a light-front quark model
Energy Technology Data Exchange (ETDEWEB)
Gutsche, Thomas [Universitaet Tuebingen, Institut fuer Theoretische Physik, Kepler Center for Astro and Particle Physics, Tuebingen (Germany); Lyubovitskij, Valery E. [Universitaet Tuebingen, Institut fuer Theoretische Physik, Kepler Center for Astro and Particle Physics, Tuebingen (Germany); Tomsk State University, Department of Physics, Tomsk (Russian Federation); Tomsk Polytechnic University, Laboratory of Particle Physics, Mathematical Physics Department, Tomsk (Russian Federation); Universidad Tecnica Federico Santa Maria, Departamento de Fisica y Centro Cientifico Tecnologico de Valparaiso (CCTVal), Valparaiso (Chile); Schmidt, Ivan [Universidad Tecnica Federico Santa Maria, Departamento de Fisica y Centro Cientifico Tecnologico de Valparaiso (CCTVal), Valparaiso (Chile)
2017-02-15
Continuing our analysis of parton distributions in the nucleon, we extend our light-front quark model in order to obtain both the helicity-independent and the helicity-dependent parton distributions, analytically matching the results of global fits at the initial scale μ∝ 1 GeV; they also contain the correct Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution. We also calculate the transverse parton, Wigner and Husimi distributions from a unified point of view, using our light-front wave functions and expressing them in terms of the parton distributions q{sub v}(x) and δq{sub v}(x). Our results are very relevant for the current and future program of the COMPASS experiment at SPS (CERN). (orig.)
Nucleon parton distributions in a light-front quark model
Gutsche, Thomas; Schmidt, Ivan
2016-01-01
Continuing with our analysis of parton distributions in the nucleon, we extend our light-front quark model in order to obtain both the helicity independent and helicity dependent parton distributions, analytically matching the results of global fits at the initial scale $\\mu \\sim 1$ GeV, and which also contain the correct Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution. We also calculate the transverse parton, Wigner and Husimi distributions from a unified point of view, using our light-front wave functions and expressing them in terms of the parton distributions $q_v(x)$ and $\\delta q_v(x)$. Our results are very relevant for the current and future program of the COMPASS experiment at SPS (CERN).
Finite Hypernuclei in the Latest Quark-Meson Coupling Model
Energy Technology Data Exchange (ETDEWEB)
Pierre A. M. Guichon; Anthony W. Thomas; Kazuo Tsushima
2007-12-12
The most recent development of the quark-meson coupling (QMC) model, in which the effect of the mean scalar field in-medium on the hyperfine interaction is also included self-consistently, is used to compute the properties of finite hypernuclei. The calculations for $\\Lambda$ and $\\Xi$ hypernuclei are of comparable quality to earlier QMC results without the additional parameter needed there. Even more significantly, the additional repulsion associated with the increased hyperfine interaction in-medium completely changes the predictions for $\\Sigma$ hypernuclei. Whereas in the earlier work they were bound by an amount similar to $\\Lambda$ hypernuclei, here they are unbound, in qualitative agreement with the experimental absence of such states. The equivalent non-relativistic potential felt by the $\\Sigma$ is repulsive inside the nuclear interior and weakly attractive in the nuclear surface, as suggested by the analysis of $\\Sigma$-atoms.
The baryon spectrum and the hypercentral Constituent Quark Model
Giannini, M M
2015-01-01
The description of the baryon spectrum is performed using the hypercentral Consituent Quark Model (hCQM), mainly in comparison with the harmonic oscillator (h.o.). Recentlly many new states, at various levels of confidence have been observed, leading to a softening of the missing resonance problem in the case of positive parity states. However, the number of negative states is higher that predicted by the commonly used h.o. scheme and therefore one is forced to take into account also the higher energy shells, which contain an overall number of states much greater than the observed one. It is shown that, thanks to the peculiar level scheme of the hCQM, the recently observed negative parity states can be considered as belonging to the lower shells, keeping the missing resonance problem within more acceptable limits.
The mass spectrum of double heavy baryons in new potential quark models
Directory of Open Access Journals (Sweden)
Kovalenko Vladimir
2017-01-01
Full Text Available A new approach to study the mass spectrum of double heavy baryons (QQ′q containing strange and charmed quarks is proposed. It is based on the separation of variables in the Schrodinger equation in the prolate spheroidal coordinates. Two nonrelativistic potential models are considered. In the first model, the interaction potential of the quarks is the sum of the Coulomb and non-spherically symmetrical linear confinement potential. In the second model it is assumed that the quark confinement provided by a spherically symmetric harmonic oscillator potential. In both models the mass spectrum is calculated, and a comparison with previous results from other models is performed.
Top quark forward-backward asymmetry from the 3-3-1 model
Barreto, E. Ramirez; Coutinho, Y. A.; Sá Borges, J.
2011-03-01
The forward-backward asymmetry AFB in top quark pair production, measured at the Tevatron, is probably related to the contribution of new particles. The Tevatron result is more than a 2σ deviation from the standard model prediction and motivates the application of alternative models introducing new states. However, as the standard model predictions for the total cross section σtt and invariant mass distribution Mtt for this process are in good agreement with experiments, any alternative model must reproduce these predictions. These models can be placed into two categories: One introduces the s-channel exchange of new vector bosons with chiral couplings to the light quarks and to the top quark, and another relies on the t-channel exchange of particles with large flavor-violating couplings in the quark sector. In this work, we employ a model which introduces both s- and t-channel nonstandard contributions for the top quark pair production in proton-antiproton collisions. We use the minimal version of the SU(3)C⊗SU(3)L⊗U(1)X model (3-3-1 model) that predicts the existence of a new neutral gauge boson, called Z'. This gauge boson has both flavor-changing couplings to up and top quarks and chiral coupling to the light quarks and to the top quark. This very peculiar model coupling can correct the AFB for top quark pair production for two ranges of Z' mass while leading to a cross section and invariant mass distribution quite similar to the standard model ones. This result reinforces the role of the 3-3-1 model for any new physics effect.
Equation of state and transition temperatures in the quark-hadron hybrid model
Miyahara, Akihisa; Torigoe, Yuhei; Kouno, Hiroaki; Yahiro, Masanobu
2016-07-01
We analyze the equation of state of 2 +1 flavor lattice QCD at zero baryon density by constructing a simple quark-hadron hybrid model that has both quark and hadron components simultaneously. We calculate the hadron and quark contributions separately and parameterize those to match with lattice QCD data. Lattice data on the equation of state are decomposed into hadron and quark components by using the model. The transition temperature is defined by the temperature at which the hadron component is equal to the quark one in the equation of state. The transition temperature thus obtained is about 215 MeV; this is somewhat higher than the chiral and the deconfinement pseudocritical temperatures defined by the temperature at which the susceptibility or the absolute value of the derivative of the order parameter with respect to temperature becomes maximum.
Minkowski space pion model inspired by lattice QCD running quark mass
Mello, Clayton S.; de Melo, J. P. B. C.; Frederico, T.
2017-03-01
The pion structure in Minkowski space is described in terms of an analytic model of the Bethe-Salpeter amplitude combined with Euclidean Lattice QCD results. The model is physically motivated to take into account the running quark mass, which is fitted to Lattice QCD data. The pion pseudoscalar vertex is associated to the quark mass function, as dictated by dynamical chiral symmetry breaking requirements in the limit of vanishing current quark mass. The quark propagator is analyzed in terms of a spectral representation, and it shows a violation of the positivity constraints. The integral representation of the pion Bethe-Salpeter amplitude is also built. The pion space-like electromagnetic form factor is calculated with a quark electromagnetic current, which satisfies the Ward-Takahashi identity to ensure current conservation. The results for the form factor and weak decay constant are found to be consistent with the experimental data.
Top Quark Chromomagnetic Dipole Moment in the Littlest Higgs Model with T-Parity
Institute of Scientific and Technical Information of China (English)
YUE Chong-Xing; LI Ding
2008-01-01
The littlest Higgs model with T-parity, which is called LHT model, predicts the existence of the new particles, such as heavy top quarks, heavy gauge bosons, and mirror fermions. We calculate the one-loop contributions of these new particles to the top quark chromomagnetic dipole moment (CMDM) △K. We find that the contribution of the LHT model is one order of magnitude smaller than the standard model prediction value.
Composite model of quark-leptons and duality
Das, C R; Laperashvili, Larisa
2006-01-01
In the present investigation the model of preons and their composites is constructed in the framework of the superstring-inspired flipped E_6\\times \\tilde E_6 gauge group of symmetry which reveals a generalized dual symmetry. We assume that preons are dyons, which in our model are confined by hyper-magnetic strings - composite N = 1 supersymmetric non-Abelian flux tubes created by the condensation of spreons near the Planck scale. We show that the six types of strings having fluxes \\Phi_n = n\\Phi_0 (n = \\pm 1,\\pm 2,\\pm 3) produce three generations of composite quark-leptons and bosons. We give an explanation of hierarchies of masses in the Standard Model. The following values of masses obtained in our preonic model: m_t\\approx 173 GeV, m_c\\approx 1 GeV and m_u\\approx 4 MeV, m_b \\approx 4 GeV, m_s\\approx 140 MeV and m_d\\approx 4 MeV, m_\\tau\\approx 2 GeV \\quad and m_\\mu \\approx 100 MeV, are in agreement with the experimentally known results. The following left-handed neutrino masses are predicted: m_1\\approx 1....
Covariant quark model of form factors in the heavy mass limit
Yaouanc, A. Le; Oliver, L; Pène, O.; Raynal, J. -C.
1995-01-01
We show that quark models of current matrix-elements based on the Bakamjian-Thomas construction of relativistic states with a fixed number of particles, plus the additivity assumption, are covariant in the heavy-quark limit and satisfy the full set of heavy-quark symmetry relations discovered by Isgur and Wise. We find the lower bound of $\\rho^2$ in such models to be $3/4$ for ground state mesons, independently of any parameter. Another welcome property of these models is that in the infinite...
△△ Dibaryon Structure in Extended Chiral SU(3) Quark Model
Institute of Scientific and Technical Information of China (English)
DAI Lian-Rong
2005-01-01
@@ The structure of △△ dibaryon is studied in the extended chiral SU(3) quark model in which vector meson exchanges are included. The effect of the vector meson fields is very similar to that of the one-gluon exchange (OGE) interaction. Both in the chiral SU(3) quark model and in the extended chiral SU(3) quark model, the resultant mass of the △△ dibaryon is lower than the threshold of the △△ channel but higher than that of the△Nπ channel.
QMC approach based on the Bogoliubov independent quark model of the nucleon
Bohr, Henrik; Panda, Prafulla K; Providencia, Constanca; da Providencia, Joao
2015-01-01
The quark-meson coupling model due to Guichon is formulated on the basis of the independent quark model of the nucleon proposed by Bogoliubov and is applied to the phenomenological descriptions of symmetric and asymmetric nuclear matter. For symmetric matter, the model predicts, at saturation density, the incompressibility $K=335.17$ MeV, the quark effective mass $m_q^*=238.5$ MeV, and the effective nucleon mass $M^*= 0.76 M,$ where $M$ is the nucleon mass in vacuum. Neutron star massesabove two solar masses are obtained.
Charmed decays of the B-meson in the quark model
Grach, I L; Ter-Martirosian, K A; Simula, S
1996-01-01
Exclusive and inclusive, semileptonic and non-leptonic, charmed decays of the B-meson are investigated in the context of a phenomenological quark model. Bound-state effects are taken care of by adopting a single (model-dependent) non-perturbative wave function, describing the motion of the light spectator quark in the B-meson. A nice reproduction of both exclusive and inclusive semileptonic data is obtained. Our predictions for the electron spectrum are presented and compared with those of the Isgur-Scora-Grinstein-Wise quark model. Finally, our approach is applied to the calculation of inclusive non-leptonic widths, obtaining a remarkable agreement with experimental findings.
Fragmentation functions of pions and kaons in the nonlocal chiral quark model
Directory of Open Access Journals (Sweden)
Kao Chung Wen
2014-03-01
Full Text Available We investigate the unpolarized pion and kaon fragmentation functions using the nonlocal chiral-quark model. In this model the interactions between the quarks and pseudoscalar mesons is manifested nonlocally. In addition, the explicit flavor SU(3 symmetry breaking effect is taken into account in terms of the current quark masses. The results of our model are evaluated to higher Q2 value Q2 = 4 GeV2 by the DGLAP evolution. Then we compare them with the empirical parametrizations. We find that our results are in relatively good agreement with the empirical parametrizations and the other theoretical estimations.
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.
Directory of Open Access Journals (Sweden)
Ulrich K. W. Neumann
2008-07-01
Full Text Available The first two parts of this article series dealt with the questions: What is a quark? and What is mass? While the present models lead to a physical idea of the mass, the geometrical theory of the general relativity only shows the effect of mass. From the physical idea of mass, from the idea of the resultant vector (EV as electric flux and from the ideas relating to the magnetic monopole (MMP it follows that the gravitational field is an electrical field. The share of the electrical gravitational flux on the entire electrical flux of a quark is determined from Newton's empirical gravitational constant. The superposition of the fluxes of two quark collectives produces the gravitational force effect between two quark collectives. Gravitational fields reach infinitely far according to our current ideas. Connected with the quark oscillations hinted in the Parts I and II this results in the idea of the flux spreading with infinite speed, having enormous consequences.
Two-solar-mass hybrid stars: a two model description with the Nambu-Jona-Lasinio quark model
Pereira, Renan Câmara; Providência, Constança
2016-01-01
Hybrid stars with a quark phase described by the Nambu$-$Jona-Lasinio model are studied. The hadron-quark model used to determine the stellar matter equation of state favors the appearance of quark matter: the coincidence of the deconfinement and chiral transitions and a low vacuum constituent quark mass. These two properties are essential to build equations of state that predict pure quark matter in the center of neutron stars. The effect of vector-isoscalar and vector-isovector terms is discussed, and it is shown that the vector-isoscalar terms are necessary to describe 2$M_\\odot$ hybrid stars, and the vector-isovector terms result in larger quark cores and a smaller deconfinement density.
The Top Quark as a Window to Beyond the Standard Model Physics
Energy Technology Data Exchange (ETDEWEB)
Yu, Chiu-Tien [Univ. of Wisconsin, Madison, WI (United States)
2013-01-01
The top quark was the last of the Standard Model quarks to be discovered, and is of considerable interest. The closeness of the top quark mass to the electroweak scale is suggestive that the top quark could be closely related to the mechanisms for electroweak symmetry breaking. Any new physics in electroweak symmetry breaking models could then preferentially couple to the top quark, making the top quark a promising probe for new physics. In this thesis, we will explore two aspects of the top quark as a harbinger to new physics: the top forward-backward asymmetry as seen at the Tevatron and the search for stops. In this thesis, we will discuss the Asymmetric Left-Right Model (ALRM), a model that is based on the gauge group $U'(1)\\times SU(2)\\times SU'(2)$ with couplings $g_1^\\prime, g_2^\\prime,$ and $g'$ associated with the fields $B',W,W'$, respectively, and show how this model can explain the top forward-backward asymmetry. We will then explore the scalar sector of the ALRM, and provide a specific Higgs mechanism that provides the masses for the $W'$ and $Z'$ bosons. The top forward-backward asymmetry is a test of invariance of charge-conjugation. Thus, we look at the $X$-gluon model, a model that was motivated by the top forward-backward asymmetry, and show that one can look at the longitudinal polarization of the top-quark to test parity conservation. Finally, we investigate searches for stop squarks, the supersymmetric partner of the top quark, at the Large Hadron Collider (LHC) using shape-based analyses.
Multiplicity fluctuation and correlation of identified baryons in a quark combination model
Song, Jun; Li, Hai-hong; Wang, Rui-qin; Shao, Feng-lan
2017-01-01
The dynamical multiplicity fluctuations and correlations of identified baryons and antibaryons produced by the hadronization of a bulk quark system are systematically studied in a quark combination model. Starting from the most basic dynamics of the quark combination which is necessary for multiplicity study, we analyze moments (variance, skewness, and kurtosis) of inclusive multiplicity distributions of identified baryons, two-baryon multiplicity correlations, and baryon-antibaryon multiplicity correlations after the hadronization of a quark system with given quark number and antiquark number. We obtain a series of interesting results, e.g., binomial behavior of multiplicity moments, coinciding flavor-dependent two-baryon correlation, and universal baryon-antibaryon correlation, which can be regarded as general features of the quark combination. We further take into account correlations and fluctuations of quark numbers before hadronization and study their influence on multiple production of baryons and antibaryons. We find that quark number fluctuations and flavor conservation lead to a series of important results such as the negative p Ω¯ + multiplicity correlation and universal two-baryon correlations. We also study the influence of resonance decays in order to compare our results with future experimental data in ultrarelativistic heavy ion collisions at the Large Hadron Collider.
A Timeon Model of Quark and Lepton Mass Matrices
Friedberg, R
2009-01-01
It is proposed that $T$ violation in physics, as well as the masses of electron and $u, d$ quarks, arise from a pseudoscalar interaction with a new spin 0 field $\\tau(x)$, odd in $P$ and $T$, but even in $C$. This interaction contains a factor $i\\gamma_5$ in the quark and lepton Dirac algebra, so that the full Hamiltonian is $P$, $T$ conserving; but by spontaneous symmetry breaking, the new field $\\tau(x)$ has a nonzero expectation value $\
String Models for the Heavy Quark-Antiquark Bound States.
Tse, Sze-Man
1988-12-01
The heavy quark-antiquark bound state is examined in the phenomenological string models. Specifically, the Nambu-Goto model and the Polyakov's smooth string model are studied in the large-D limit, D being the number of transverse space-time dimensions. The static potential V(R) is extracted in both models in the large-D limit. In the former case, this amounts to the usual saddle point calculation. In the latter case, the renormalized, physical string tension is expressed in terms of the bare string tension and the extrinsic curvature coupling. A systematic loop expansion of V(R) is developed and carried out explicitly to one loop order, with the two loops result presented without detail. For large separations R, the potential is linear in R with corrections of order 1/R. The coefficient of the 1/R Luscher term has the universal value -piD/24 to any finite order in the loop expansion. For very small separations R, the potential V(R) is also proportional to 1/R with a coefficient twice that of Luscher's term. The corrections are logarithmically small. Polyakov's smooth string model is extended to the finite temperature situation. The temperature dependence of the string tension is investigated in the large-D limit. The effective string tension is calculated to the second order in the loop expansion. At low temperature, it differs from that of the Nambu-Goto model only by terms that fall exponentially with inverse temperature. Comparison of the potential V(R) in the smooth string model with lattice gauge calculation and hadron spectroscopy data yields a consistent result.
Seeking Texture Zeros in the Quark Mass Matrix Sector of the Standard Model
Giraldo, Yithsbey
2015-01-01
Here we show that the Weak Basis Transformation is an appropriate mathematical tool that can be used to find texture zeros in the quark mass matrix sector of the Standard Model. So, starting with the most general quark mass matrices and taking physical data into consideration, is possible to obtain more than three texture zeros by any weak basis transformation. Where the most general quark mass matrices considered in the model, were obtained through a special weak basis wherein the mass matrix $M_u$~(or $M_d$) has been taken to be diagonal and only the matrix $M_d$~(or $M_u$) is considered to be most general.
Subtraction of Spurious Centre-of-Mass Motion in Quark Delocalization and Colour Screening Model
Institute of Scientific and Technical Information of China (English)
CHEN Ling-Zhi; PANG Hou-Rong; HUANG Hong-Xia; PING Jia-Lun; WANG Fan
2007-01-01
The quark delocalization colour screening model provides an alternative approach for the NN intermediate range attraction, which is attributed to the σ meson exchange in the meson exchange and chiral quark model.However the quark delocalization induces the spurious centre-of-mass motion (CMM). A method for subtracting the spurious CMM proposed before is applied to the new scattering calculation. The subtraction of the spurious CMM results in an additional NN attraction. The NN scattering data are refitted by a fine tune of the colour screening constant.
Study of Ratio of Proton Momentum Distributions with a Chiral Quark Model
Institute of Scientific and Technical Information of China (English)
LIU Jian; DONG Yu-Bing
2005-01-01
The ratio between the anomalous magnetic moments of proton and neutron has recently been suggested to be connected to the ratio of proton momentum fractions carried by the valence quarks inside it. This moment fraction ratio is respectively evaluated by using constituent quark model and chiral quark model in order to check meson cloud effect. Our results show that the meson cloud effect is remarkable to the ratio of the proton momentum fractions, and therefore, this ratiois a sensitive test for the meson cloud effect as well as for the SU(6) symmetry breaking effect.
Indian Academy of Sciences (India)
V K Gupta; Asha Gupta; S Singh; J D Anand
2003-10-01
We report on the study of the mass–radius (–) relation and the radial oscillations of magnetized proto strange stars. For the quark matter we have employed the very recent modiﬁcation, the temperature- and density-dependent quark mass model of the well-known density-dependent quark mass model. We ﬁnd that the effect of magnetic ﬁeld, both on the maximum mass and radial frequencies, is rather small. Also a proto strange star, whether magnetized or otherwise, is more likely to evolve into a strange star rather than transform into a black hole.
Semileptonic decays of $\\Lambda_b$ baryons in the relativistic quark model
Faustov, R N
2016-01-01
Semileptonic $\\Lambda_b$ decays are investigated in the framework of the relativistic quark model based on the quasipotential approach and the quark-diquark picture of baryons. The decay form factors are expressed through the overlap integrals of the initial and final baryon wave functions. All calculations are done without employing nonrelativistic and heavy quark expansions. The momentum transfer dependence of the decay form factors is explicitly determined in the whole accessible kinematical range without any extrapolations or model assumptions. Both the heavy-to-heavy $\\Lambda_b\\to\\Lambda_c\\ell\
Axial form factors of the octet baryons in a covariant quark model
Ramalho, G
2015-01-01
We study the weak interaction axial form factors of the octet baryons, within the covariant spectator quark model, focusing on the dependence of four-momentum transfer squared, Q^2. In our model the axial form factors G_A(Q^2) (axial-vector form factor) and G_P(Q^2) (induced pseudoscalar form factor), are calculated based on the constituent quark axial form factors and the octet baryon wave functions. The quark axial current is parametrized by the two constituent quark form factors, the axial-vector form factor g_A^q(Q^2), and the induced pseudoscalar form factor g_P^q(Q^2). The baryon wave functions are composed of a dominant S-state and a P-state mixture for the relative angular momentum of the quarks. First, we study in detail the nucleon case. We assume that the quark axial-vector form factor g_A^q(Q^2) has the same function form as that of the quark electromagnetic isovector form factor. The remaining parameters of the model, the P-state mixture and the Q^2-dependence of g_P^q(Q^2), are determined by a f...
Finite Nuclei in the Quark-Meson Coupling (QMC) Model
Stone, J R; Reinhard, P G; Thomas, A W
2016-01-01
We report the first use of the effective QMC energy density functional (EDF), derived from a quark model of hadron structure, to study a broad range of ground state properties of even-even nuclei across the periodic table in the non-relativistic Hartree-Fock+BCS framework. The novelty of the QMC model is that the nuclear medium effects are treated through modification of the internal structure of the nucleon. The density dependence is microscopically derived and the spin-orbit term arises naturally. The QMC EDF depends on a single set of four adjustable parameters having clear physical basis. When applied to diverse ground state data the QMC EDF already produces, in its present simple form, overall agreement with experiment of a quality comparable to a representative Skyrme EDF. There exist however multiple Skyrme paramater sets, frequently tailored to describe selected nuclear phenomena. The QMC EDF parameter set is not open to such variation, chosen set being applied, without adjustment, to both the propert...
A model of quarks with Δ(6N{sup 2}) family symmetry
Energy Technology Data Exchange (ETDEWEB)
Ishimori, Hajime [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan); King, Stephen F. [School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ (United Kingdom)
2014-07-30
We propose a first model of quarks based on the discrete family symmetry Δ(6N{sup 2}) in which the Cabibbo angle is correctly determined by a residual Z{sub 2}×Z{sub 2} subgroup, and the smaller quark mixing angles may be qualitatively understood from the model. The present model of quarks may be regarded as a first step towards formulating a complete model of quarks and leptons based on Δ(6N{sup 2}), in which the lepton mixing matrix is fully determined by a Klein subgroup. For example, the choice N=28 provides an accurate determination of both the reactor angle and the Cabibbo angle.
Quark and Lepton Mass Matrix Model with Only Six Family-Independent Parameters
Koide, Yoshio
2015-01-01
We propose a unified mass matrix model for quarks and leptons, in which sixteen observables of mass ratios and mixings of the quarks and neutrinos are described by using no family number-dependent parameters except for the charged lepton masses and only six family number-independent free parameters. The model is constructed by extending the so-called ``Yukawaon" model to a seesaw type model with the smallest number of possible family number-independent free parameters. As a result, once the six parameters is fixed by the quark mixing and the mass ratios of quarks and neutrinos, no free parameters are left in the lepton mixing matrix. The results are in excellent agreement with the neutrino mixing data. We predict $\\delta_{CP}^\\ell =-68^\\circ$ for the leptonic $CP$ violating phase and $\\langle m\\rangle\\simeq 21$ meV for the effective Majorana neutrino mass.
Path Dependence of the Quark Nonlocal Condensate within the Instanton Model
Trevisan, L A; Tomio, Lauro; Tomio, Lauro
2004-01-01
Within the instanton liquid model, we study the dependence of the gauge invariant two--point quark correlator on the path used to perform the color parallel transport between two points in the Euclidean space.
Institute of Scientific and Technical Information of China (English)
PANG Hou-Rong; PING Jia-Lun; WANG Fan; ZHAO En-Guang
2004-01-01
Promising high strangeness dibaryons are studied by the extended quark delocalization and color screening model. It is shown that besides H particle and di-Ω, there might be other dibaryon candidates worth to be searched experimentally such as NΩ.
Vector and axial vector mesons in a nonlocal chiral quark model
Izzo Villafañe, M. F.; Gómez Dumm, D.; Scoccola, N. N.
2016-09-01
Basic features of nonstrange vector and axial vector mesons are analyzed in the framework of a chiral quark model that includes nonlocal four-fermion couplings. Unknown model parameters are determined from some input values of masses and decay constants, while nonlocal form factors are taken from a fit to lattice QCD results for effective quark propagators. Numerical results show a good agreement with the observed meson phenomenology.
Describing the strongly interacting quark-gluon plasma through the Friedberg-Lee model
Shu, Song; Li, Jia-Rong
2010-10-01
The Friedberg-Lee (FL) model is studied at finite temperature and density. The soliton solutions of the FL model in the deconfinement phase transition are solved and thoroughly discussed for certain boundary conditions. We indicate that the solitons before and after the deconfinement have different physical meanings: the soliton before deconfinement represents hadrons, while the soliton after the deconfinement represents the bound state of quarks which leads to a strongly interacting quark-gluon plasma phase. The corresponding phase diagram is given.
Vector and axial vector mesons in a nonlocal chiral quark model
Villafañe, M F Izzo; Scoccola, N N
2016-01-01
Basic features of nonstrange vector and axial vector mesons are analyzed in the framework of a chiral quark model that includes nonlocal four fermion couplings. Unknown model parameters are determined from some input values of masses and decay constants, while nonlocal form factors are taken from a fit to lattice QCD results for effective quark propagators. Numerical results show a good agreement with the observed meson phenomenology.
De Sanctis, M; Santopinto, E; Vassallo, A
2015-01-01
We briefly describe our relativistic quark-diquark model, developed within the framework of point form dynamics, which is the relativistic extension of the interacting quark-diquark model. In order to do that we have to show the main properties and quantum numbers of the effective degree of freedom of constituent diquark. Our results for the nonstrange baryon spectrum and for the nucleon electromagnetic form factors are discussed.
$\\Xi$ baryon strong decays in a chiral quark model
Xiao, Li-Ye
2013-01-01
The strong decays of $\\Xi$ baryons up to N=2 shell were studied in a chiral quark model. The strong decay properties of these well-established ground decuplet baryons were reasonably described. We found that (i) $\\Xi(1690)$ and $\\Xi(1820)$ could be assigned to the spin-parity $J^P=1/2^-$ state $|70,^{2}{8},1,1,1/2^->$ and the spin-parity $J^P=3/2^-$ state $|70,^{2}{8},1,1,3/2^->$, respectively. Slight configuration mixing might exist in these two negative parity states. (ii) $\\Xi(1950)$ might correspond to several different $\\Xi$ resonances. The broad states ($\\Gamma\\sim 100$ MeV) observed in the $\\Xi\\pi$ channel could be classified as the pure $J^P=5/2^-$ octet state $\\Xi^0|70,^{4}8,1,1,5/2^->$ or the mixed state $|\\Xi 1/2^->_3 $ with $J^P=1/2^-$. The $\\Xi$ resonances with moderate width ($\\Gamma\\sim 60$ MeV) observed in the $\\Xi\\pi$ channel might correspond to the $J^P=1/2^+$ excitation $|56,^{4}10,2,2,1/2^+>$. The second orbital excitation $|56,^{4}10,2,2,3/2^+>$ and the mixed state $|\\Xi 1/2^->_1$ might b...
Polarizability of. pi. mesons in the confined quark model
Energy Technology Data Exchange (ETDEWEB)
Avakyan, E.Z.; Avakyan, S.L.; Efimov, G.V.; Ivanov, M.A. (Joint Institute for Nuclear Research, Dubna (USSR))
1989-05-01
The electric polarizabilities {alpha}{sub {pi}} and magnetic {beta}{sub {pi}} polarizabilities of {pi}{sup +} and {pi}{sup 0} mesons are calculated using the confined quark model. Diagrams with intermediate vector ({rho},{omega}), axial-vector ({ital a}{sub 1}, {ital f}{sub 1}), and scalar ({Epsilon}, {ital f}{sub 0}) states are included. It turns out that the intermediate mesons contribute significantly to the pion electric and magnetic polarizabilities. The following values (in units of 10{sup {minus}43} cm{sup 3}) are obtained: {alpha}{sub {pi}{sup +}}=5.8, {beta}{sub {pi}{sup +}}={minus}5.6, {alpha}{sub {pi}{sup 0}}={minus}1.1, and {beta}{sub {pi}{sup 0}}=2.8. The widths of two-particle strong and radiative decays of scalar mesons are calculated. The results are compared with the available experimental data and the results of other approaches.
$ND$ and $NB$ systems in quark delocalization color screening model
Zhao, Lifang; Ping, Jialun
2016-01-01
The $ND$ and $NB$ systems with $I=0$ and $1$, $J^{P}=\\frac{1}{2}^{\\pm}$, $\\frac{3}{2}^{\\pm}$, and $\\frac{5}{2}^{\\pm}$ are investigated within the framework of quark delocalization color screening model. The results show that all the positive parity states are unbound. By coupling to the $ND^{*}$ channel, the state $ND$ with $I=0,~J^{P}=\\frac{1}{2}^{-}$ can form a bound state, which can be invoked to explain the observed $\\Sigma(2800)$ state. The mass of the $ND^{*}$ with $I=0,~J^{P}=\\frac{3}{2}^{-}$ is close to that of the reported $\\Lambda_{c}(2940)^{+}$, which indicates that $\\Lambda_{c}(2940)^{+}$ can be explained as a $ND^{*}$ molecular state in QDCSM. Besides, the $\\Delta D^{*}$ with $I=1,~J^{P}=\\frac{5}{2}^{-}$ is also a possible resonance state. The results of the bottom case of $NB$ system are similar to those of the $ND$ system. Searching for these states will be a challenging subject of experiments.
ND and NB systems in quark delocalization color screening model
Energy Technology Data Exchange (ETDEWEB)
Zhao, Lifang [Nanjing College of Information Technology, Department of Quality-Oriented Education, Nanjing (China); Huang, Hongxia; Ping, Jialun [Nanjing Normal University, Department of Physics, Nanjing (China)
2017-02-15
The ND and NB systems with I = 0 and 1, J{sup P} = (1)/(2){sup ±}, (3)/(2){sup ±}, and (5)/(2){sup ±} are investigated within the framework of the quark delocalization color screening model. The results show that all the positive-parity states are unbound. By coupling to the ND* channel, the state ND with I = 0, J{sup P} = (1)/(2){sup -} can form a bound state, which can be invoked to explain the observed Σ(2800) state. The mass of the ND* with I = 0, J{sup P} = (3)/(2){sup -} is close to that of the reported Λ{sub c}(2940){sup +}, which indicates that Λ{sub c}(2940){sup +} can be explained as a ND* molecular state in QDCSM. Besides, the ΔD* with I = 1, J{sup P} = (5)/(2){sup -} is also a possible resonance state. The results of the bottom case of the NB system are similar to those of the ND system. Searching for these states will be a challenging subject of experiments. (orig.)
Unquenched quark-model calculation of X(3872) electromagnetic decays
Energy Technology Data Exchange (ETDEWEB)
Cardoso, Marco [Universidade de Lisboa, Centro de Fisica Teorica de Particulas, Instituto Superior Tecnico, Lisbon (Portugal); Rupp, George [Universidade de Lisboa, Centro de Fisica das Interaccoes Fundamentais, Instituto Superior Tecnico, Lisbon (Portugal); Beveren, Eef van [Universidade de Coimbra, Departamento de Fisica, Centro de Fisica Computacional, Coimbra (Portugal)
2015-01-01
A recent quark-model description of X(3872) as an unquenched 2{sup 3}P{sub 1} c anti c state is generalised by now including all relevant meson.meson configurations, in order to calculate the widths of the experimentally observed electromagnetic decays X(3872) → γJ/ψ and X(3872) → γψ(2S). Interestingly, the inclusion of additional two-meson channels, most importantly D{sup ±}D{sup *-+}, leads to a sizeable increase of the c anti c probability in the total wave function, although the D{sup 0} anti D{sup *0} component remains the dominant one. As for the electromagnetic decays, unquenching strongly reduces the γψ(2S) decay rate; yet it even more sharply enhances the γJ/ψ rate, resulting in a decay ratio compatible with one experimental observation but in slight disagreement with two others. Nevertheless, the results show a dramatic improvement as compared to a quenched calculation with the same confinement force and parameters. Concretely, we obtain Γ (X(3872) → γψ(2S)) = 28.9 keV and Γ (X(3872) → γJ/ψ) = 24.7 keV, with branching ratio R{sub γψ} = 1.17. (orig.)
From QCD to a dynamical quark model: construction and some meson spectroscopy
Dudal, D; Palhares, L F; Sorella, S P
2013-01-01
We introduce an effective quark model that is in principle dynamically derivable from the QCD action. An important feature is the incorporation of spontaneous chiral symmetry breaking in a renormalizable fashion. The quark propagator in the condensed vacuum exhibits complex conjugate poles, indicative of an unphysical spectral form, i.e. confined quarks. Moreover, the ensuing mass function can be fitted well to existing lattice data. To validate the physical nature of the new model, we identify not only a massless pseudoscalar (i.e. a pion) in the chiral limit, but we also present reasonable estimates for the rho meson mass and decay constant, employing a contact point interaction and a large N argument to simplify the diagrammatic spectral analysis. We stress that we do not use any experimental input to obtain our numbers, but only rely on our model and lattice quark data.
Pion generalized parton distributions within a fully covariant constituent quark model
Energy Technology Data Exchange (ETDEWEB)
Fanelli, Cristiano [Massachusetts Institute of Technology, Cambridge, MA (United States). Lab. for Nuclear Science; Pace, Emanuele [' ' Tor Vergata' ' Univ., Rome (Italy). Physics Dept.; INFN Sezione di TorVergata, Rome (Italy); Romanelli, Giovanni [Rutherford-Appleton Laboratory, Didcot (United Kingdom). STFC; Salme, Giovanni [Istituto Nazionale di Fisica Nucleare, Rome (Italy); Salmistraro, Marco [Rome La Sapienza Univ. (Italy). Physics Dept.; I.I.S. G. De Sanctis, Rome (Italy)
2016-05-15
We extend the investigation of the generalized parton distribution for a charged pion within a fully covariant constituent quark model, in two respects: (1) calculating the tensor distribution and (2) adding the treatment of the evolution, needed for achieving a meaningful comparison with both the experimental parton distribution and the lattice evaluation of the so-called generalized form factors. Distinct features of our phenomenological covariant quark model are: (1) a 4D Ansatz for the pion Bethe-Salpeter amplitude, to be used in the Mandelstam formula for matrix elements of the relevant current operators, and (2) only two parameters, namely a quark mass assumed to be m{sub q} = 220 MeV and a free parameter fixed through the value of the pion decay constant. The possibility of increasing the dynamical content of our covariant constituent quark model is briefly discussed in the context of the Nakanishi integral representation of the Bethe-Salpeter amplitude. (orig.)
The quark-meson coupling model for $\\Lambda$, $\\Sigma$ and $\\Xi$ hypernuclei
Tsushima, K; Haidenbauer, J; Thomas, A W
1998-01-01
The quark-meson coupling (QMC) model, which has been successfully used to describe the properties of both infinite nuclear matter and finite nuclei, is applied to a systematic study of $\\Lambda, \\Sigma$ and $\\Xi$ hypernuclei. Assumptions made in the present study are, (i) the (self-consistent) exchanged scalar, and vector, mesons couple only to the u and d quarks, and (ii) an SU(6) valence quark model for the bound nucleons and hyperon. The model automatically leads to a very weak spin-orbit interaction for the $\\Lambda$ in a hypernucleus. Effects of the Pauli blocking at the quark level, and the $\\Sigma N - \\Lambda N$ channel coupling (strong conversion), are also taken into account in a phenomenological way.
Qq(-Q)(-q)'States in Chiral SU(3) Quark Model
Institute of Scientific and Technical Information of China (English)
ZHANG Hai-Xia; ZHANG Min; ZHANG Zong-Ye
2007-01-01
We study the masses of Qq(-Q)(-q)'states with JPC = 0++, 1++, 1+- and 2++ in the chiral SU(3) quark model,where Q is the heavy quark (c or b) and q (q') is the light quark (u, d or s). According to our numerical results, it is improbable to make the interpretation of [cn(-c)(-n)]1++ and [cn(-c)(-n)]2++ (n = u, d) states as X(3872) and Y(3940),respectively. However, it is interesting to find the tetraquarks in the bq(-b)(-q)'system.
Strangeness content and structure function of the nucleon in a statistical quark model
Trevisan, L A; Tomio, L
1999-01-01
The strangeness content of the nucleon is determined from a statistical model using confined quark levels, and is shown to have a good agreement with the corresponding values extracted from experimental data. The quark levels are generated in a Dirac equation that uses a linear confining potential (scalar plus vector). With the requirement that the result for the Gottfried sum rule violation, given by the new muon collaboration (NMC), is well reproduced, we also obtain the difference between the structure functions of the proton and neutron, and the corresponding sea quark contributions. (27 refs).
Studies on top-quark Monte Carlo modelling for Top2016
The ATLAS collaboration
2016-01-01
This note summarises recent studies on Monte Carlo simulation setups of top-quark pair production used by the ATLAS experiment and presents a new method to deal with interference effects for the $Wt$ single-top-quark production which is compared against previous techniques. The main focus for the top-quark pair production is on the improvement of the modelling of the Powheg generator interfaced to the Pythia8 and Herwig7 shower generators. The studies are done using unfolded data at centre-of-mass energies of 7, 8, and 13 TeV.
Self-consistent description of $\\Lambda$ hypernuclei in the quark-meson coupling model
Tsushima, K; Thomas, A W
1997-01-01
The quark-meson coupling model, which has been successfully used to describe the properties of both finite nuclei and infinite nuclear matter, is applied to a study of $\\Lambda$ hypernuclei. With the assumption that the (self-consistent) exchanged scalar, and vector, mesons couple only to the u and d quarks, a very weak spin-orbit force in the $\\Lambda$-nucleus interaction is achieved automatically. This can be interpreted as a direct consequence of the quark structure of the $\\Lambda$ hyperon. Possible implications and extensions of the present investigation are also discussed.
The neutron electric dipole form factor in the perturbative chiral quark model
Dib, C; Gutsche, T; Kovalenko, S; Kuckei, J; Lyubovitskij, V E; Pumsa-ard, K; Dib, Claudio; Faessler, Amand; Gutsche, Thomas; Kovalenko, Sergey; Kuckei, Jan; Lyubovitskij, Valery E.; Pumsa-ard, Kem
2006-01-01
We calculate the electric dipole form factor of the neutron in a perturbative chiral quark model, parameterizing CP-violation of generic origin by means of effective electric dipole moments of the constituent quarks and their CP-violating couplings to the chiral fields. We discuss the relation of these effective parameters to more fundamental ones such as the intrinsic electric and chromoelectric dipole moments of quarks and the Weinberg parameter. From the existing experimental upper limits on the neutron EDM we derive constraints on these CP-violating parameters.
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)
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)
Top quark and Higgs physics in standard model extensions
Energy Technology Data Exchange (ETDEWEB)
Gonzalez, Patrick Jose
2012-05-25
In this thesis we have studied several extensions of the SM and their implications on the strength and structure of the tbW vertex, on the production and decays of pseudoscalar and heavy Higgs scalars at the LHC, and the effects that models with a fourth generation have on electroweak precision observables. Apart from the SM with a fourth generation of chiral fermions, the extensions we studied all feature an extended electroweak symmetry breaking (EWSB) sector. In the case of the type-II 2HDM and the MSSM, the extended EWSB sector consists of elementary Higgs fields. In the case of Topcolor assisted Technicolor (TC2), which is a model of dynamical EWSB, the scalar and pseudoscalar fields are composite. By scanning over the phenomenologically and theoretically allowed regions of the respective parameters spaces, we determined the largest possible cross sections σ(pp→φ→VV{sup '}) where VV{sup p}rime element of {W"+W"-, ZZγγ, Zγ} for both the heavy scalar and pseudoscalar states in the above models. We found that non-SUSY models with an extended Higgs sector and only three generations, namely the type-II 2HDM and the TC2, still allow for observable pseudoscalar cross sections σ(pp → A → VV') at the LHC. In particular for the final states W{sup +}W{sup -} and γγ. In the MSSM, the discovery of the pseudoscalar A through its decays into electroweak gauge bosons is very unlikely. However, scalar cross sections σ(pp→H→W{sup +}W{sup -}) can still be of observable size at the LHC in large parts of the MSSM parameter space. SM extensions with an extended EWSB sector and four chiral generations are strongly disfavoured; direct Higgs boson searches exclude large parts of the parameter space and it is challenging to bring such an extension into accordance with electroweak precision data. On the other hand, models with additional vector-like quarks and an extended Higgs sector are still viable. The SM with four chiral generations is (still) not
Analytic properties of the quark propagator from an effective infrared interaction model
Windisch, Andreas
2017-04-01
In this paper, I investigate the analytic properties of the quark propagator Dyson-Schwinger equation (DSE) in the Landau gauge. In the quark self-energy, the combined gluon propagator and quark-gluon vertex is modeled by an effective interaction (the so-called Maris-Tandy interaction), where the ultraviolet term is neglected. This renders the loop integrand of the quark self-energy analytic on the cut plane -π Supplemental Material, which can be used to parametrize solutions of the complex quark propagator for a wide range of bare mass values and for large bound-state masses. This study is a first step towards an extension of previous work on the analytic continuation of perturbative one-loop integrals, with the long-term goal of establishing a framework that allows for the numerical extraction of the analytic properties of the quark propagator with a truncation that extends beyond the rainbow by making adequate adjustments in the contour of the radial integration of the quark self-energy.
Nucleon structure functions and longitudinal spin asymmetries in the chiral quark constituent model
Dahiya, Harleen
2016-01-01
We have analysed the phenomenological dependence of the spin independent ($F_1^{p,n}$ and $F_2^{p,n}$) and the spin dependent ($g_1^{p,n}$) structure functions of the nucleon on the the Bjorken scaling variable $x$ using the unpolarized distribution functions of the quarks $q(x)$ and the polarized distribution functions of the quarks $\\Delta q(x)$ respectively. The chiral constituent quark model ($\\chi$CQM), which is known to provide a satisfactory explanation of the proton spin crisis and related issues in the nonperturbative regime, has been used to compute explicitly the valence and sea quark flavor distribution functions of $p$ and $n$. In light of the improved precision of the world data, the $p$ and $n$ longitudinal spin asymmetries ($A_1^p(x)$ and $A_1^n(x)$) have been calculated. The implication of the presence of the sea quarks has been discussed for ratio of polarized to unpolarized quark distribution functions for up and down quarks in the $p$ and $n$ $\\frac{\\Delta u^p(x)}{u^p(x)}$, $\\frac{\\Delta d...
Droplets in the cold and dense linear sigma model with quarks
Palhares, Leticia F
2010-01-01
The linear sigma model with quarks at very low temperatures provides an effective description for the thermodynamics of the strong interaction in cold and dense matter, being especially useful at densities found in compact stars and protoneutron star matter. Using the MSbar one-loop effective potential, we compute quantities that are relevant in the process of nucleation of droplets of quark matter in this scenario. In particular, we show that the model predicts a surface tension of \\Sigma ~ 5-15 MeV/fm^2, rendering nucleation of quark matter possible during the early post-bounce stage of core collapse supernovae. Including temperature effects and vacuum logarithmic corrections, we find a clear competition between these features in characterizing the dynamics of the chiral phase conversion, so that if the temperature is low enough the consistent inclusion of vacuum corrections could help preventing the nucleation of quark matter during the collapse process. We also discuss the first interaction corrections th...
Leptonic decay of light vector mesons in an independent quark model
Energy Technology Data Exchange (ETDEWEB)
Barik, N. (Department of Physics, Utkal University, Bhubaneswar-751004 (India)); Dash, P.C. (Department of Physics, P. N. College, Khurda, Orissa (India)); Panda, A.R. (Department of Physics, Kendrapara College, Kendrapara, Orissa (India))
1993-02-01
Leptonic decay widths of light vector mesons are calculated in a framework based on the independent quark model with a scalar-vector harmonic potential. Assuming a strong correlation to exist between the quark-antiquark momenta inside the meson, so as to make their total momentum identically zero in the center-of-mass frame of the meson, we extract the quark and antiquark momentum distribution amplitudes from the bound quark eigenmode. Using the model parameters determined from earlier studies, we arrive at the leptonic decay widths of ([rho],[omega],[phi]) as (6.26 keV, 0.67 keV, 1.58 keV) which are in very good agreement with the respective experimental data (6.77[plus minus]0.32 keV, 0.6[plus minus]0.02 keV, 1.37[plus minus]0.05 keV).
Interpretation of Vector-like Quark Searches: Heavy Gluons in Composite Higgs Models
Araque, Juan Pedro; Santiago, Jose
2015-01-01
Pair production of new vector-like quarks in pp collisions is considered model independent as it is usually dominated by QCD production. We discuss the interpretation of vector-like quark searches in the case that QCD is not the only relevant production mechanism for the new quarks. In particular we consider the effect of a new massive color octet vector boson with sizeable decay branching ratio into the new quarks. We pay special attention to the sensitivity of the Large Hadron Collider experiments, both in run-1 and early run-2, to differences in the kinematical distributions from the different production mechanisms. We have found that even though there can be significant differences in some kinematical distributions at the parton level, the differences are washed out at the reconstruction level. Thus, the published experimental results can be reinterpreted in models with heavy gluons by simply rescaling the production cross section.
Quark deconfinement in the proto-magnetar model of Long Gamma-Ray Bursts
Pili, A G; Drago, A; Pagliara, G; Del Zanna, L
2016-01-01
We investigate the possible implications of quark deconfinement on the phenomenology of Long Gamma-Ray Bursts focusing, in particular, on the possibility to describe multiple prompt emission phases in the context of the proto-magnetar model. Starting from numerical models of rotating Hadron Stars and Quark Stars in full general relativity we track the electromagnetic spin-down evolution in both the hadronic and quark phase, linking the two families through conservation of baryon number and angular momentum. We give estimates of the timescales and the energetics involved in the spin-down process deriving, in the relevant spin range, the relation between the initial and the final masses and rotational energies, whenever hadron-quark conversion is possible. We show how the results can be used in relevant astrophysical cases such as the double burst GRB 110709B.
Quark deconfinement in the proto-magnetar model of long gamma-ray bursts
Pili, A. G.; Bucciantini, N.; Drago, A.; Pagliara, G.; Del Zanna, L.
2016-10-01
We investigate the possible implications of quark deconfinement on the phenomenology of long gamma-ray bursts focusing, in particular, on the possibility to describe multiple prompt emission phases in the context of the proto-magnetar model. Starting from numerical models of rotating Hadron Stars and Quark Stars in full general relativity we track the electromagnetic spin-down evolution in both the hadronic and quark phase, linking the two families through conservation of baryon number and angular momentum. We give estimates of the time-scales and the energetics involved in the spin-down process deriving, in the relevant spin range, the relation between the initial and the final masses and rotational energies, whenever hadron-quark conversion is possible. We show how the results can be used in relevant astrophysical cases such as the double burst GRB 110709B.
Relativistic three-body quark model of light baryons based on hypercentral approach
Aslanzadeh, M.; Rajabi, A. A.
2015-05-01
In this paper, we have treated the light baryons as a relativistic three-body bound system. Inspired by lattice QCD calculations, we treated baryons as a spin-independent three-quark system within a relativistic three-quark model based on the three-particle Klein-Gordon equation. We presented the analytical solution of three-body Klein-Gordon equation with employing the constituent quark model based on a hypercentral approach through which two- and three-body forces are taken into account. Herewith the average energy values of the up, down and strange quarks containing multiplets are reproduced. To describe the hyperfine structure of the baryon, the splittings within the SU(6)-multiplets are produced by the generalized Gürsey Radicati mass formula. The considered SU(6)-invariant potential is popular "Coulomb-plus-linear" potential and the strange and non-strange baryons spectra are in general well reproduced.
Meiling, Yu; Lianshou, Liu
2008-01-01
Pair distribution function for delocalized quarks in the strongly coupled quark gluon plasma (sQGP) as well as in the states at intermediate stages of crossover from hadronic matter to sQGP are calculated using a molecule-like aggregation model. The shapes of the obtained pair distribution functions exhibit the character of liquid. The increasing correlation length in the process of crossover indicates a diminishing viscosity of the fluid system.
Study of pesudoscalar transition form factors within light front quark model
Geng, Chao-Qiang
2012-01-01
We study the transition form factors of the pesudoscalar mesons ($\\pi,\\eta$ and $\\eta^{\\prime}$) as functions of the momentum transfer $Q^2$ within the light-front quark model. We compare our results with the recent experimental data by CELLO, CLEO, BaBar and Belle. By considering the possible uncertainties from the quark masses, we illustrate that our predicted form factors can fit with all the data, including those at the large $Q^2$ regions.
The effect of instanton-induced interaction on -wave meson spectra in constituent quark model
Indian Academy of Sciences (India)
Bhavyashri; S Sarangi; Godfrey Saldanha; K B Vijaya Kumar
2008-01-01
The mass spectrum of the -wave mesons is considered in a non-relativistic constituent quark model. The full Hamiltonian used in the investigation includes the kinetic energy, the confinement potential, the one-gluon-exchange potential (OGEP) and the instanton-induced quark-antiquark interaction (III). A good description of the mass spectrum is obtained. The respective role of III and OGEP in the P-wave meson spectrum is discussed.
Single Production of Heavy Top Quark from Three-Site Higgsless Model
Institute of Scientific and Technical Information of China (English)
YUE Chong-Xing; WANG Li-Hong; WEN Jia
2008-01-01
We consider single production of the heavy top quark T predicted by the three-site Higgsless model in future high energy collider experiments,such as the high energy linear e+e- collider (ILC),the linear-ring type ep collider (THERA),and the CERN Large Hadron Collider (LHC).Our numerical results show that the possible signals of the heavy top quark T might be detected via the subprocess qb→ q'T at the LHC.
Electromagnetic nucleon-delta transition in the perturbative chiral quark model
Pumsa-ard, K; Gutsche, T; Faessler, A; Cheedket, S; Gutsche, Th.; Faessler, Amand
2003-01-01
We apply the perturbative chiral quark model to the gamma N -> Delta transition. The four momentum dependence of the respective transverse helicity amplitudes A(1/2) and A(3/2) is determined at one loop in the pseudoscalar Goldstone boson fluctuations. Inclusion of excited states in the quark propagator is shown to result in a reasonable description of the experimental values for the helicity amplitudes at the real photon point.
Self-bound quark matter in the NJL model revisited: from schematic droplets to solitonic lasagne
Buballa, Michael
2012-01-01
The existence and the properties of self-bound quark matter in the NJL model at zero temperature are investigated in mean-field approximation, focusing on inhomogeneous structures with one-dimensional spatial modulations. It is found that the most stable homogeneous solutions which have previously been interpreted as schematic quark droplets are unstable against formation of a one-dimensional soliton-antisoliton lattice. The solitons repel each other, so that the minimal energy per quark is realized in the single-soliton limit. The properties of the solitons and their interactions are discussed in detail, and the effect of vector interactions is estimated. The results may be relevant for the dynamics of expanding quark matter.
Indian Academy of Sciences (India)
N Barik; R N Mishra
2001-04-01
Considering the nucleon as consisting entirely of its valence quarks conﬁned independently in a scalar-vector harmonic potential; unpolarized structure functions 1(,2) and 2(x,2) are derived in the Bjorken limit under certain simplifying assumptions; from which valence quark distribution functions (,2) and (,2) are appropriately extracted satisfying the normalization constraints. QCD-evolution of these input distributions from a model scale of 2=0.07 GeV2 to a higher $Q^{2}$ scale of $Q^{2}_{0} = 15$ GeV2 yields (, $Q^{2}_{0}$) and (, $Q^{2}_{0}$) in good agreement with experimental data. The gluon and sea-quark distributions such as (,$Q^{2}_{0}$) and (, $Q^{2}_{0}$) are dynamically generated with a reasonable qualitative agreement with the available data; using the leading order renormalization group equations with appropriate valence-quark distributions as the input.
Quark Loop Effects on Dressed Gluon Propagator in Framework of Global Color Symmetry Model
Institute of Scientific and Technical Information of China (English)
ZONG Hong-Shi; SUN Wei-Min
2006-01-01
Based on the global color symmetry model (GCM), a method for obtaining the quark loop effects on the dressed gluon propagator in GCM is developed. In the chiral limit, it is found that the dressed gluon propagator containing the quark loop effects in the Nambu-Goldstone and Wigner phases are quite different. In solving the quark self-energy functions in the two different phases and subsequent study of bag constant one should use the above dressed gluon propagator as input. The above approach for obtaining the current quark mass effects on the dressed gluon propagator is quite general and can also be used to calculate the chemical potential dependence of the dressed gluon propagator.
Abnormal Structure of Fermion Mixings in a Seesaw Quark Mass Matrix Model
Koide, Y
1997-01-01
It is pointed out that in a seesaw quark mass matrix model which yields a singular enhancement of the top-quark mass, the right-handed fermion-mixing matrix U_R^u for the up-quark sector has a peculiar structure in contrast to the left-handed one U_L^u. As an example of the explicit structures of U_L^u and U_R^u, a case in which the heavy fermion mass matrix M_F is given by a form [(unit matrix)+(rank-one matrix)] is investigated. As a consequence, one finds observable signatures at projected high energy accelerators like the production of a fourth heavy quark family.
Quasiparticle properties of the quarks of the Nambu-Jona-Lasinio model
Cao, Nan-Wei; Shakin, C. M.; Sun, Wei-Dong
1992-12-01
In spite of the apparent limitations of the model, in recent years there have been many applications of the Nambu-Jona-Lasinio (NJL) model in the study of hadron structure and in the study of the behavior of nuclear matter at finite temperature and density. A number of researchers have studied a generalized SU(3) version of the NJL model. For example, Vogl, Lutz, Klimt, and Weise [Nucl. Phys. A516 469 (1990)] have performed extensive calculations that include a calculation of a scalar form factor of a constituent quark, Fs(q2), and a calculation of a quark sigma term σq. (In their work, the latter quantity is related to the nucleon sigma term σN as in a constituent quark model: σN=3σq.) These calculations are made in what may be termed a sigma-dominance approximation. In the work reported here, we review the important role played by the nucleon sigma term in understanding the behavior of the quark condensate in the presence of matter. We make use of the original SU(2) version of the NJL model to study how various quark properties are modified when we take into account the dressing of the constituent quarks by the pion, the Goldstone boson of the model. We calculate the quark self-energy arising from emission and absorption of a pion and also show how the calculation of the scalar form factor of the quark and σq are modified due to the coupling of the quark to the pion. The correction terms considered here serve to reduce the value of σq by a small amount relative to the value obtained in the simplest version of the sigma dominance model. For example, for a Euclidean momentum cutoff, Λ=1050 MeV, the uncorrected result is σN=54.6 MeV. That value is then reduced to σN=51.5 MeV, if the corrections due to the pion ``dressing'' are included. It is also found that the residue at the quasiparticle pole of the quark propagator Z is about 0.86 when the coupling to the pion field is taken into account.
Flavour changing neutral currents in the standard model and its extensions with singlet quarks
Bejlin, V A; Kuksa, V I
2001-01-01
The review is devoted to the phenomenology of singlet quarks, which are singlets with respect to the SU(2), have hypercharges Y = -1/3 masses m > m sub t. It is shown, that experimental data on rare processes and the corresponding theoretical predictions of the Standard Model (SM) allow to invoke the SM extensions for the analysis of the phenomena stimulated by flavor changing neutral current. The extended matrix of standard and singlet quark mixing is constructed, the restriction on mixing angles and the estimate of low bound of singlet quark mass m sub D >= 0.5 TeV are obtained. Besides the direct observation the perspectives to increase the confidence level of the singlet quark existence are discussed. The cross-sections of nondiagonal production of singlet quark in pair with standard one in e sup - e sup + -, ep- and pp-bar-collisions are analyzed and the unique signature of such events is described. The model of up-singlet quark with the hypercharge Y sub U 2/3 and its applications to the physics of t-qu...
Top quark forward-backward asymmetry from the $3-3-1$ model
Barreto, E Ramirez; Borges, J Sá
2011-01-01
The forward-backward asymmetry $A_{FB}$ in top quark pair production, measured at the Tevatron, is probably related to the contribution of new particles. The Tevatron result is more than a $2\\sigma$ deviation from the standard model prediction and motivates the application of alternative models introducing new states. However, as the standard model predictions for the total cross section $\\sigma_{tt}$ and invariant mass distribution $M_{tt}$ for this process are in good agreement with experiments, any alternative model must reproduce these predictions. These models can be placed into two categories: One introduces the s-channel exchange of new vector bosons with chiral couplings to the light quarks and to the top quark and another relies on the t-channel exchange of particles with large flavor-violating couplings in the quark sector. In this work we employ a model which introduces both s- and t-channel nonstandard contributions for the top quark pair production in proton antiproton collisions. We use the mini...
Masses and Internal Structure of Mesons in the String Quark Model
Soloviev, L D
2000-01-01
The relativistic quantum string quark model, proposed earlier, is applied to all mesons, from pion to $\\Upsilon$, lying on the leading Regge trajectories (i.e., to the lowest radial excitations in terms of the potential quark models). The model describes the meson mass spectrum, and comparison with measured meson masses allows one to determine the parameters of the model: current quark masses, universal string tension, and phenomenological constants describing nonstring short-range interaction. The meson Regge trajectories are in general nonlinear; practically linear are only trajectories for light-quark mesons with non-zero lowest spins. The model predicts masses of many new higher-spin mesons. A new $K^*(1^-)$ meson is predicted with mass 1910 Mev. In some cases the masses of new low-spin mesons are predicted by extrapolation of the phenomenological short-range parameters in the quark masses. In this way the model predicts the mass of $\\eta_b(1S)(0^{-+})$ to be $9500\\pm 30$ MeV, and the mass of $B_c(0^-)$ t...
LHC Limits on the Top-Higgs in Models with Strong Top-Quark Dynamics
Chivukula, R Sekhar; Logan, Heather E; Martin, Adam; Simmons, Elizabeth H
2011-01-01
LHC searches for the standard model Higgs Boson in WW or ZZ decay modes place strong constraints on the top-Higgs state predicted in many models with new dynamics preferentially affecting top quarks. Such a state couples strongly to top-quarks, and is therefore produced through gluon fusion at a rate enhanced relative to the rate for the standard model Higgs boson. A top-Higgs state with mass less than 300 GeV is excluded at 95% CL if the associated top-pion has a mass of 150 GeV, and the constraint is even stronger if the mass of the top-pion state exceeds the top-quark mass or if the top-pion decay constant is a substantial fraction of the weak scale. These results have significant implications for theories with strong top dynamics, such as topcolor-assisted technicolor, top-seesaw models, and certain Higgsless models.
Uraltsev Sum Rule in Bakamjian-Thomas Quark Models addendum
Le Yaouanc, A; Oliver, L; Pène, O; Raynal, J C
2001-01-01
In previous work it has been shown that, either from a sum rule for the subleading Isgur-Wise function $\\xi_3(1)$ or from a combination of Uraltsev and Bjorken SR, one infers for $P$-wave states $|\\tau_{1/2}(1)| \\ll |\\tau_{3/2}(1)|$. This implies, in the heavy quark limit of QCD, a hierarchy for the {\\it production} rates of $P$-states $\\Gamma(\\bar{B}_d \\to D ({1 \\over 2}) \\ell \
Two types of glitches in a solid quark star model
Lu, Jiguang; Zhou, Enping
2015-01-01
TThe glitch of anomalous X-ray pulsars \\& soft gamma repeaters (AXP/SGRs) usually accompanied with detectable energy releases manifesting as X-ray bursts or outbursts, while the glitch of some pulsars like Vela release negligible energy. We find that these two types of glitches can naturally correspond to two types of starquake of solid strange stars. By applying the EoS of quark cluster star and some realistic pulsar parameters, we can reproduce consistent results compared with previous cons...
Quasiparticle properties of the quarks of the Nambu--Jona-Lasinio model
Energy Technology Data Exchange (ETDEWEB)
Cao, N.; Shakin, C.M.; Sun, W. (Department of Physics and Center for Nuclear Theory, Brooklyn College of the City University of New York, Brooklyn, New York 11210 (United States))
1992-12-01
In spite of the apparent limitations of the model, in recent years there have been many applications of the Nambu--Jona-Lasinio (NJL) model in the study of hadron structure and in the study of the behavior of nuclear matter at finite temperature and density. A number of researchers have studied a generalized SU(3) version of the NJL model. For example, Vogl, Lutz, Klimt, and Weise (Nucl. Phys. A516 469 (1990)) have performed extensive calculations that include a calculation of a scalar form factor of a constituent quark, {ital F}{sub {ital s}}({ital q}{sup 2}), and a calculation of a quark sigma term {sigma}{sub {ital q}}. (In their work, the latter quantity is related to the nucleon sigma term {sigma}{sub {ital N}} as in a constituent quark model: {sigma}{sub {ital N}}=3{sigma}{sub {ital q}}.) These calculations are made in what may be termed a sigma-dominance approximation. In the work reported here, we review the important role played by the nucleon sigma term in understanding the behavior of the quark condensate in the presence of matter. We make use of the original SU(2) version of the NJL model to study how various quark properties are modified when we take into account the dressing of the constituent quarks by the pion, the Goldstone boson of the model. We calculate the quark self-energy arising from emission and absorption of a pion and also show how the calculation of the scalar form factor of the quark and {sigma}{sub {ital q}} are modified due to the coupling of the quark to the pion. The correction terms considered here serve to reduce the value of {sigma}{sub {ital q}} by a small amount relative to the value obtained in the simplest version of the sigma dominance model. For example, for a Euclidean momentum cutoff, {Lambda}=1050 MeV, the uncorrected result is {sigma}{sub {ital N}}=54.6 MeV.
On Possible S-Wave Bound States for an N-(N) System Within a Constituent Quark Model
Institute of Scientific and Technical Information of China (English)
CHANG Chao-Hsi; PANG Hou-Rong
2005-01-01
We try to apply a constituent quark model (a variety chiral constituent quark model) and the resonating group approach for the multi-quark problems to compute the effective potential between the NN- in S-wave (the quarks in the nucleons N and N-, and the two nucleons relatively as well, are in S wave) so as to see the possibility if there may be a tight bound state of six quarks as indicated by a strong enhancement at threshold of pp- in J/ψ and B decays. The effective potential which we obtain in terms of the model and approach shows if the experimental enhancement is really caused by a tight S-wave bound state of six quarks, then the quantum number of the bound state is very likely to be I = 1, JPC= 0-+.
Decay constants in the heavy quark limit in models à la Bakamjian and Thomas
Morénas, V; Oliver, L; Pène, O; Raynal, J C
1998-01-01
In quark models à la Bakamjian and Thomas, that yield covariance and Isgur-Wise scaling of form factors in the heavy quark limit, we compute the decay constants $f^{(n)}$ and $f^{(n)}_{1/2}$ of S-wave and P-wave mesons composed of heavy and light quarks. Heavy quark limit scaling $\\sqrt{M} f = Cst$ is obtained, and it is shown that this class of models satisfies the sum rules involving decay constants and Isgur-Wise functions recently formulated by us in the heavy quark limit of QCD. Moreover, the model also satisfies the selection rules of the type $f^{(n)}_{3/2} = 0$ that must hold in this limit. We discuss different Ansätze for the dynamics of the mass operator at rest. For non-relativistic kinetic energies ${p^2 \\over 2m}$ the decay constants are finite even if the potential $V(r)$ has a Coulomb part. For the relativistic form $\\sqrt{p^2 + m^2}$, the S-wave decay constants diverge if there is a Coulomb singularity. Using phenomenological models of the spectrum with relativistic kinetic energy and regula...
Indian Academy of Sciences (India)
Yuji Takeuchi
2012-10-01
Since the top quark was discovered at Tevatron in 1995, many top quark properties have been measured. However, the top quark is still interesting due to unique features which originate from the extremely heavy mass, and providing various test grounds on the Standard Model as well as searches for a new physics. Though the measurements of the top quark had been performed only at Tevatron so far, LHC is now ready for measurements with more top quarks than Tevatron. In this article, recent measurements of top quark properties from Tevatron (CDF and DØ) as well as LHC (ATLAS and CMS) are presented.
Magnetic catalysis and inverse magnetic catalysis in nonlocal chiral quark models
Pagura, V. P.; Gómez Dumm, D.; Noguera, S.; Scoccola, N. N.
2017-02-01
We study the behavior of strongly interacting matter under an external constant magnetic field in the context of nonlocal chiral quark models within the mean field approximation. We find that at zero temperature the behavior of the quark condensates shows the expected magnetic catalysis effect, our predictions being in good quantitative agreement with lattice QCD results. On the other hand, in contrast to what happens in the standard local Nambu-Jona-Lasinio model, when the analysis is extended to the case of finite temperature, our results show that nonlocal models naturally lead to the inverse magnetic catalysis effect.
Magnetic catalysis and inverse magnetic catalysis in nonlocal chiral quark models
Pagura, V P; Noguera, S; Scoccola, N N
2016-01-01
We study the behavior of strongly interacting matter under an external constant magnetic field in the context of nonlocal chiral quark models within the mean field approximation. We find that at zero temperature the behavior of the quark condensates shows the expected magnetic catalysis effect, our predictions being in good quantitative agreement with lattice QCD results. On the other hand, in contrast to what happens in the standard local Nambu-Jona-Lasinio model, when the analysis is extended to the case of finite temperature our results show that nonlocal models naturally lead to the Inverse Magnetic Catalysis effect.
Scalar quantum chromodynamics in two dimensions and parton model. [Scalar quarks, SU(N) groups
Energy Technology Data Exchange (ETDEWEB)
Shei, S.S.; Tsao, H.S.
1977-05-01
The SU(N) scalar quantum chromodynamics in two space-time dimensions in the large N limit are studied. This is the model of color gauge fields interacting with scalar quarks. It is found that the consensual properties of the four dimensional QCD, i.e., the infrared slavery, quark confinement, the charmonium picture etc. are all realized. Moreover, the current in this model mimics nicely the behaviors of current in the four dimensional QCD, in contrast to the original model of 't Hooft.
Pion Structure at High and Low Energies in Chiral Quark Models
Ruiz-Arriola, E
2002-01-01
Low and high energy properties of the pion are reviewed in the framework of chiral quark models. Particular emphasis is put on the simplest version of the SU(2) NJL model as prototype. The role of gauge invariance in this kind of calculations is stressed. The results are used as initial conditions for perturbative QCD evolution equations. At leading order the quark model scale is $\\mu_0 \\sim 320 {\\rm MeV} $ as determined from the pion distribution functions and the pion distribution amplitudes.
Isospin properties of quark matter from a 3-flavor NJL model
Liu, He; Xu, Jun; Chen, Lie-Wen; Sun, Kai-Jia
2016-09-01
We have studied the properties of hot and dense quark matter based on the 3-flavor Nambu-Jona-Lasinio (NJL) model as well as its Polyakov-loop extension (pNJL) with scalar-isovector and vector-isovector couplings. Provided a considerable large isospin asymmetry or isospin chemical potential, isospin splittings of constituent mass, chiral phase transition boundary, and critical point for u and d quarks can be observed for positive isovector coupling constants but are suppressed for negative ones. The quark matter symmetry energy decreases with the increasing isovector coupling constant, and is mostly enhanced in the pNJL model than in the NJL model. A positive scalar-isovector coupling constant is more likely to lead to an unstable isospin asymmetric quark matter. The isovector coupling has been further found to affect particle fractions as well as the equation of state in hybrid stars. Possible effects on the isospin properties of quark matter have also been discussed if the strangeness sector is further broken among the flavor symmetry.
Study of the $ar{D}$N Interaction in a QCD Coulomb Gauge Quark Model
Directory of Open Access Journals (Sweden)
Vizcarra V.E.
2010-04-01
Full Text Available We study the $ar{D}$N interaction at low energies with a quark model inspired in the QCD Hamiltonian in Coulomb gauge. The model Hamiltonian incorporates a conﬁning Coulomb potential extracted from a self-consistent quasiparticle method for the gluon degrees of freedom, and transverse-gluon hyperﬁne interaction consistent with a ﬁnite gluon propagator in the infrared. Initially a constituent-quark mass function is obtained by solving a gap equation and baryon and meson bound-states are obtained in Fock space using a variational calculation. Next, having obtained the constituent-quark masses and the hadron waves functions, an eﬀective meson-nucleon interaction is derived from a quark-interchange mechanism. This leads to a short range mesonbaryon interaction and to describe long-distance physics vector- and scalar-meson exchanges described by eﬀective Lagrangians are incorporated. The derived eﬀective $ar{D}$N potential is used in a Lippmann-Schwinger equation to obtain phase shifts. The results are compared with a recent similar calculation using the nonrelativistic quark model.
Thermodynamics and phase structure of the Polyakov-Quark-Meson model
Energy Technology Data Exchange (ETDEWEB)
Braun, Jens [Institut fuer Kernphysik (Theoriezentrum), Technische Universitaet Darmstadt (Germany); ExtreMe Matter Institute EMMI, GSI (Germany); Fraga, Eduardo S. [Instituto de Fisica, Universidade Federal do Rio de Janeiro (Brazil); Institut fuer Theoretische Physik, Goethe-Universitaet Frankfurt (Germany); Haas, Lisa M.; Pawlowski, Jan M. [Institut fuer Theoretische Physik, Universitaet Heidelberg (Germany); ExtreMe Matter Institute EMMI, GSI (Germany); Herbst, Tina K.; Stiele, Rainer [Institut fuer Theoretische Physik, Universitaet Heidelberg (Germany); Mintz, Bruno W.; Ramos, Rudnei O. [Departamento de Fisica Teorica, Universidade do Estado do Rio de Janeiro (Brazil); Mitter, Mario [Institut fuer Theoretische Physik, Universitaet Heidelberg (Germany); Institut fuer Theoretische Physik, Goethe-Universitaet Frankfurt (Germany); Schaefer, Bernd-Jochen [Institut fuer Theoretische Physik, Justus-Liebig-Universitaet Giessen (Germany); Institut fuer Physik, Karl-Franzens-Universitaet Graz (Austria); Schaffner-Bielich, Juergen [Institut fuer Theoretische Physik, Goethe-Universitaet Frankfurt (Germany)
2014-07-01
Polyakov-loop extended chiral effective models are important tools to describe the phase structure and thermodynamics of strongly interacting matter. We show that taking into account the backreaction of quarks onto the gauge sector is crucial in such models to achieve results for the order parameters and thermodynamics that are in line with lattice calculations. Achieving a good description of lattice data at zero density, we test the reliability of those models in systems containing other control parameters besides the temperature by confronting its results with lattice data at nonzero isospin. Furthermore, we investigate the phase structure of the three-dimensional T-μ{sub isospin}-μ{sub quark} phase diagram and calculate the surface tension of the first order phase transition at small temperatures and large quark densities.
B --> D$**$ semileptonic decay in covariant quark models à la Bakamjian-Thomas
Morénas, V; Oliver, L; Pène, O; Raynal, J C
1996-01-01
Once chosen the dynamics in one frame, for example the rest frame, the Bakamjian and Thomas method allows to define relativistic quark models in any frame. These models have been shown to provide, in the heavy quark limit, fully covariant current form factors as matrix elements of the quark current operator. They also verify the Isgur-Wise scaling and give a slope parameter \\rho^2>3/4 for all the possible choices of the dynamics. In this paper we study the L=1 excited states and derive the general formula, valid for any dynamics, for the scaling invariant form factors \\tau_{1/2}^{(n)}(w) and \\tau_{3/2}^{(n)}(w). We also check the Bjorken-Isgur-Wise sum rule already demonstrated elsewhere in this class of models.
Study of Proto Strange Stars (PSS) in Temperature and Density Dependent Quark Mass Model
Gupta, V K; Singh, S; Anand, J D; Gupta, Asha
2003-01-01
We report on the study of the mass-radius (M-R) relation and the radial oscillations of proto strange stars. For the quark matter we have employed the well known density dependent quark mass model and its very recent modification, the temperature and density dependent quark mass model. We find that the maximum mass the star can support increases significantly with the temperature of the star in this model which implies that transition to a black hole at the early stage of formation of the star is inhibited. As for the neutrinos, we find, contrary to the expectation that the M-R and oscillation frequencies are almost independent of the neutrino chemical potentials.
Production of {omega}{sub bbc} and {omega}{sub bcc} baryons in quark-diquark model
Energy Technology Data Exchange (ETDEWEB)
Gomshi Nobary, M.A. [Department of Physics, Faculty of Science, Razi University, Kermanshah (Iran, Islamic Republic of)]. E-mail: mnobary@razi.ac.ir; Nikoobakht, B. [Department of Physics, Faculty of Science, Razi University, Kermanshah (Iran, Islamic Republic of); Naji, J. [Department of Physics, Faculty of Science, Razi University, Kermanshah (Iran, Islamic Republic of)
2007-06-01
Using perturbative quantum chromodynamics and quark-diquark model of baryons, we have obtained an analytical fragmentation function which describes {omega}{sub bbc} and {omega}{sub bcc} baryons in b and c quarks fragmentation. The universal fragmentation probabilities, the average fragmentation parameters and the production cross sections resulting from this function are in a very good agreement with those obtained using a full perturbative regime. We conclude that the quark-diquark model of baryons works well when a scalar heavy diquark is considered in a heavy quark fragmentation into a triply heavy baryon.
XcJ Decays into B(B-) in Quark-Pair Creation Model
Institute of Scientific and Technical Information of China (English)
PING Rong-Gang; JIANG Huan-Qing
2004-01-01
A quark pair creation model is introduced to study the XcJ exclusive decays into baryon-antibaryon pairs.The decay widths for processes XcJ → BB- ( J ＝ 0, 2; B = A, ∑0, E-) are evaluated phenomenologicaily with an explicit inclusion of the properties for outgoing baryons described by wave functions in the naive quark model. The results show that states XcJ (J = 0, 2) decay into A pair with a larger branching ratio than into p(p-) pair.
Exclusive photoproduction of $\\phi$ on Proton in the quark-diquark model
Carimalo, C; Ong, S
1999-01-01
We present predictions for the exclusive photoproduction of $\\Phi$-meson on Proton at large tranfer, where we use a quark-diquark structure model for the proton. Extrapolation from our results to lower tranfers is comparable in magnitude with available data in that range. This may support the diquark model in its ability to provide, for that process, an appropriate link between diffractive physics at low transfer and the standard semi-perturbative approach of hard exclusive processes at very large tranfer, where the proton recovers its three-quark structure.
Radiative decay of mesons in an independent-quark potential model
Energy Technology Data Exchange (ETDEWEB)
Barik, N.; Dash, P.C. (Department of Physics, Utkal University, Bhubaneswar 751004 (India)); Panda, A.R. (Department of Physics, Kendrapara College, Kendrapara, Orissa (India))
1992-11-01
We investigate in a potential model of independent quarks the {ital M}1 transitions among the low-lying vector ({ital V}) and pseudoscalar ({ital P}) mesons. We perform a static'' calculation of the partial decay widths of twelve possible {ital M}1 transitions such as {ital V}{r arrow}{ital P}{gamma} and {ital P}{r arrow}{ital V}{gamma} within the traditional picture of photon emission by a confined quark and/or antiquark. The model accounts well for the observed decay widths.
How I got to work with Feynman on the covariant quark model
Ravndal, Finn
2014-01-01
In the period 1968 - 1974 I was a graduate student and then a postdoc at Caltech and was involved with the developments of the quark and parton models. Most of this time I worked in close contact with Richard Feynman and thus was present from the parton model was proposed until QCD was formulated. A personal account is presented how the collaboration took place and how the various stages of this development looked like from the inside until QCD was established as a theory for strong interactions with the partons being quarks and gluons.
Institute of Scientific and Technical Information of China (English)
DONG Yu-Bing; FENG Qing-Guo
2002-01-01
Based on a relativistic quark model approach, the transition properties of the first nucleon resonance △(1232), and the coupling constants gπNN, g△πN are investigated. Tvo different vays to remove the center of mass motion are considered. The results of the relativistic approaches with and without center ofmass correction are compared with those of nonrelativistic constituent quark model. Moreover, pion meson cloud effect on these calculated observables is explicitly addressed. Better results are obtained by taking the pion meson cloud into account.
Exact duality and Bjorken sum rule in heavy quark models à la Bakamjian-Thomas
Le Yaouanc, A; Pène, O; Raynal, J C
1996-01-01
The heavy mass limit of quark models based on the Bakamjian-Thomas cons\\-truction reveals remarkable features. In addition to previously demonstrated properties of covariance and Isgur-Wise scaling, exact duality, leading to the Bjorken-Isgur-Wise sum rule, is proven, for the first time to our knowledge in relativistic quark models. Inelastic as well as elastic contributions to the sum rule are then discussed in terms of ground state averages of a few number of operators corresponding to the nonrelativistic dipole operator and various relativistic corrections.
Determination of Deuteron Dipole Moment in Nuclear Quark-Like Model
Institute of Scientific and Technical Information of China (English)
N.Ghahramany; E.Yazdankish
2013-01-01
Using the quark-like model,we have improved the existing deviation between theoretical and experimental values of magnetic dipole moment of deuteron.Based upon Pauli Exclusion Principle,the constituent quarks form a ground state for l =0.The expectation value of the deuteron magnetic dipole moment operator is determined to be equal to 0.861 5978μN in better agreement with the measured value of 0.8574376μN as compared to the shell model calculations.
A search for inverse magnetic catalysis in thermal quark-meson models
Fraga, E. S.; Mintz, B. W.; Schaffner-Bielich, J.
2014-04-01
We explore the parameter space of the two-flavor thermal quark-meson model and its Polyakov loop-extended version under the influence of a constant external magnetic field B. We investigate the behavior of the pseudo critical temperature for chiral symmetry breaking taking into account the likely dependence of two parameters on the magnetic field: the Yukawa quark-meson coupling and the parameter T0 of the Polyakov loop potential. Under the constraints that magnetic catalysis is realized at zero temperature and the chiral transition at B=0 is a crossover, we find that the quark-meson model leads to thermal magnetic catalysis for the whole allowed parameter space, in contrast to the present picture stemming from lattice QCD.
A search for inverse magnetic catalysis in thermal quark-meson models
Fraga, E S; Schaffner-Bielich, J
2013-01-01
We explore the parameter space of the two-flavor thermal quark-meson model and its Polyakov loop-extended version under the influence of a constant external magnetic field $B$. We investigate the behavior of the pseudo critical temperature for chiral symmetry breaking taking into account the likely dependence of two parameters on the magnetic field: the Yukawa quark-meson coupling and the parameter $T_0$ of the Polyakov loop potential. Under the constraints that magnetic catalysis is realized at zero temperature and the chiral transition at $B=0$ is a crossover, we find that the quark-meson model leads to thermal magnetic catalysis for the whole allowed parameter space, in contrast to the present picture stemming from lattice QCD.
Model-independent measurement of the W boson helicity in top quark decays
Abazov, V M; Abolins, M; Acharya, B S; Adams, M; Adams, T; Aguiló, E; Ahn, S H; Ahsan, M; Alexeev, G D; Alkhazov, G; Alton, A; Alverson, G; Alves, G A; Anastasoaie, M; Ancu, L S; Andeen, T; Anderson, S; Andrieu, B; Anzelc, M S; Arnoud, Y; Arov, M; Arthaud, M; Askew, A; Åsman, B; Assis-Jesus, A C S; Atramentov, O; Autermann, C; Avila, C; Ay, C; Badaud, F; Baden, A; Bagby, L; Baldin, B; Bandurin, D V; Banerjee, S; Banerjee, P; Barberis, E; Barfuss, A F; Bargassa, P; Baringer, P; Barreto, J; Bartlett, J F; Bassler, U; Bauer, D; Beale, S; Bean, A; Begalli, M; Begel, M; Belanger-Champagne, C; Bellantoni, L; Bellavance, A; Benítez, J A; Beri, S B; Bernardi, G; Bernhard, R; Bertram, I; Besançon, M; Beuselinck, R; Bezzubov, V A; Bhat, P C; Bhatnagar, V; Biscarat, C; Blazey, G; Blekman, F; Blessing, S; Bloch, D; Bloom, K; Böhnlein, A; Boline, D; Bolton, T A; Borissov, G; Bose, T; Brandt, A; Brock, R; Brooijmans, G; Bross, A; Brown, D; Buchanan, N J; Buchholz, D; Bühler, M; Büscher, V; Bunichev, V; Burdin, S; Burke, S; Burnett, T H; Buszello, C P; Butler, J M; Calfayan, P; Calvet, S; Cammin, J; Carvalho, W; Casey, B C K; Cason, N M; Castilla-Valdez, H; Chakrabarti, S; Chakraborty, D; Chan, K M; Chan, K; Chandra, A; Charles, F; Cheu, E; Chevallier, F; Cho, D K; Choi, S; Choudhary, B; Christofek, L; Christoudias, T; Cihangir, S; Claes, D; Coadou, Y; Cooke, M; Cooper, W E; Corcoran, M; Couderc, F; Cousinou, M C; Crepe-Renaudin, S; Cutts, D; Cwiok, M; Da Motta, H; Das, A; Davies, G; De, K; De Jong, S J; De La Cruz-Burelo, E; De Oliveira Martins, C; Degenhardt, J D; Déliot, F; Demarteau, M; Demina, R; Denisov, D; Denisov, S P; Desai, S; Diehl, H T; Diesburg, M; Dominguez, A; Dong, H; Dudko, L V; Duflot, L; Dugad, S R; Duggan, D; Duperrin, A; Dyer, J; Dyshkant, A; Eads, M; Edmunds, D; Ellison, J; Elvira, V D; Enari, Y; Eno, S; Ermolov, P; Evans, H; Evdokimov, A; Evdokimov, V N; Ferapontov, A V; Ferbel, T; Fiedler, F; Filthaut, F; Fisher, W; Fisk, H E; Ford, M; Fortner, M; Fox, H; Fu, S; Fuess, S; Gadfort, T; Galea, C F; Gallas, E; Galyaev, E; García, C; García-Bellido, A; Gavrilov, V; Gay, P; Geist, W; Gelé, D; Gerber, C E; Gershtein, Yu; Gillberg, D; Ginther, G; Gollub, N; Gómez, B; Goussiou, A; Grannis, P D; Greenlee, H; Greenwood, Z D; Gregores, E M; Grenier, G; Gris, P; Grivaz, J F; Grohsjean, A; Grünendahl, S; Grünewald, M W; Guo, J; Guo, F; Gutíerrez, P; Gutíerrez, G; Haas, A; Hadley, N J; Haefner, P; Hagopian, S; Haley, J; Hall, I; Hall, R E; Han, L; Hansson, P; Harder, K; Harel, A; Harrington, R; Hauptman, J M; Hauser, R; Hays, J; Hebbeker, T; Hedin, D; Hegeman, J G; Heinmiller, J M; Heinson, A P; Heintz, U; Hensel, C; Herner, K; Hesketh, G; Hildreth, M D; Hirosky, R; Hobbs, J D; Hoeneisen, B; Hoeth, H; Hohlfeld, M; Hong, S J; Hossain, S; Houben, P; Hu, Y; Hubacek, Z; Hynek, V; Iashvili, I; Illingworth, R; Ito, A S; Jabeen, S; Jaffré, M; Jain, S; Jakobs, K; Jarvis, C; Jesik, R; Johns, K; Johnson, C; Johnson, M; Jonckheere, A; Jonsson, P; Juste, A; Kajfasz, E; Kalinin, A M; Kalk, J R; Kalk, J M; Kappler, S; Karmanov, D; Kasper, P A; Katsanos, I; Kau, D; Kaur, R; Kaushik, V; Kehoe, R; Kermiche, S; Khalatyan, N; Khanov, A; Kharchilava, A; Kharzheev, Yu M; Khatidze, D; Kim, T J; Kirby, M H; Kirsch, M; Klima, B; Kohli, J M; Konrath, J P; Korablev, V M; Kozelov, A V; Krop, D; Kühl, T; Kumar, A; Kunori, S; Kupco, A; Kurca, T; Kvita, J; Lacroix, F; Lam, D; Lammers, S; Landsberg, G; Lebrun, P; Lee, W M; Leflat, A; Lehner, F; Lellouch, J; Lévêque, J; Li, J; Li, Q Z; Li, L; Lietti, S M; Lima, J G R; Lincoln, D; Linnemann, J; Lipaev, V V; Lipton, R; Liu, Y; Liu, Z; Lobodenko, A; Lokajícek, M; Love, P; Lubatti, H J; Luna, R; Lyon, A L; Maciel, A K A; Mackin, D; Madaras, R J; Mättig, P; Magass, C; Magerkurth, A; Mal, P K; Malbouisson, H B; Malik, S; Malyshev, V L; Mao, H S; Maravin, Y; Martin, B; McCarthy, R; Melnitchouk, A; Mendoza, L; Mercadante, P G; Merkin, M; Merritt, K W; Meyer, J; Meyer, A; Millet, T; Mitrevski, J; Molina, J; Mommsen, R K; Mondal, N K; Moore, R W; Moulik, T; Muanza, G S; Mulders, M; Mulhearn, M; Mundal, O; Mundim, L; Nagy, E; Naimuddin, M; Narain, M; Naumann, N A; Neal, H A; Negret, J P; Neustroev, P; Nilsen, H; Nogima, H; Novaes, S F; Nunnemann, T; O'Dell, V; O'Neil, D C; Obrant, G; Ochando, C; Onoprienko, D; Oshima, N; Osta, J; Otec, R; Oteroy-Garzon, G J; Owen, M; Padley, P; Pangilinan, M; Parashar, N; Park, S J; Park, S K; Parsons, J; Partridge, R; Parua, N; Patwa, A; Pawloski, G; Penning, B; Perfilov, M; Peters, K; Peters, Y; Petroff, P; Petteni, M; Piegaia, R; Piper, J; Pleier, M A; Podesta-Lerma, P L M; Podstavkov, V M; Pogorelov, Y; Pol, M E; Polozov, P; Pope, B G; Popov, A V; Potter, C; Prado da Silva, W L; Prosper, H B; Protopopescu, S; Qian, J; Quadt, A; Quinn, B; Rakitine, A; Rangel, M S; Ranjan, K; Ratoff, P N; Renkel, P; Reucroft, S; Rich, P; Rieger, J; Rijssenbeek, M; Ripp-Baudot, I; Rizatdinova, F; Robinson, S; Rodrigues, R F; Rominsky, M; Royon, C; Rubinov, P; Ruchti, R; Safronov, G; Sajot, G; Sánchez-Hernández, A; Sanders, M P; Santoro, A; Savage, G; Sawyer, L; Scanlon, T; Schaile, A D; Schamberger, R D; Scheglov, Y; Schellman, H; Schliephake, T; Schwanenberger, C; Schwartzman, A; Schwienhorst, R; Sekaric, J; Severini, H; Shabalina, E; Shamim, M; Shary, V; Shchukin, A A; Shivpuri, R K; Siccardi, V; Simák, V; Sirotenko, V; Skubic, P; Slattery, P; Smirnov, D; Snow, J; Snow, G R; Snyder, S; Söldner-Rembold, S; Sonnenschein, L; Sopczak, A; Sosebee, M; Soustruznik, K; Spurlock, B; Stark, J; Steele, J; Stolin, V; Stoyanova, D A; Strandberg, J; Strandberg, S; Strang, M A; Strauss, M; Strauss, E; Ströhmer, R; Strom, D; Stutte, L; Sumowidagdo, S; Svoisky, P; Sznajder, A; Talby, M; Tamburello, P; Tanasijczuk, A; Taylor, W; Temple, J; Tiller, B; Tissandier, F; Titov, M; Tokmenin, V V; Toole, T; Torchiani, I; Trefzger, T; Tsybychev, D; Tuchming, B; Tully, C; Tuts, P M; Unalan, R; Uvarov, S; Uvarov, L; Uzunyan, S; Vachon, B; vanden Berg, P J; Van Kooten, R; Van Leeuwen, W M; Varelas, N; Varnes, E W; Vasilyev, I A; Vaupel, M; Verdier, P; Vertogradov, L S; Verzocchi, M; Villeneuve-Séguier, F; Vint, P; Vokac, P; Von Törne, E; Voutilainen, M; Wagner, R; Wahl, H D; Wang, L; SWang, M H L; Warchol, J; Watts, G; Wayne, M; Weber, M; Weber, G; Welty-Rieger, L; Wenger, A; Wermes, N; Wetstein, M; White, A; Wicke, D; Wilson, G W; Wimpenny, S J; Wobisch, M; Wood, D R; Wyatt, T R; Xie, Y; Yacoob, S; Yamada, R; Yan, M; Yasuda, T; Yatsunenko, Y A; Yip, K; Yoo, H D; Youn, S W; Yu, J; Zatserklyaniy, A; Zeitnitz, C; Zhao, T; Zhou, B; Zhu, J; Zielinski, M; Zieminska, D; Zieminski, A; Zivkovic, L; Zutshi, V; Zverev, E G
2007-01-01
We present the first model-independent measurement of the helicity of $W$ bosons produced in top quark decays, based on a 1 fb$^{-1}$ sample of candidate $t\\bar{t}$ events in the dilepton and lepton plus jets channels collected by the D0 detector at the Fermilab Tevatron $p\\bar{p}$ Collider. We reconstruct the angle $\\theta^*$ between the momenta of the down-type fermion and the top quark in the $W$ boson rest frame for each top quark decay. A fit of the resulting \\costheta distribution finds that the fraction of longitudinal $W$ bosons $f_0 = 0.390 \\pm 0.177 \\hbox{(stat.)} \\pm 0.104 \\hbox{(syst.)}$ and the fraction of right-handed $W$ bosons $f_+ = 0.171 \\pm 0.102 \\hbox{(stat.)} \\pm 0.058 \\hbox{(syst.)}$, which is consistent at the 27% C.L. with the standard model.
Quark flavour observables in the Littlest Higgs model with T-parity after LHC Run 1
Blanke, Monika; Recksiegel, Stefan
2016-01-01
The Littlest Higgs Model with T-parity (LHT) belongs to the simplest new physics scenarios with new sources of flavour and CP violation. We present a new analysis of quark observables in the LHT model in view of the oncoming flavour precision era. We use all available information on the CKM parameters, lattice QCD input and experimental data on quark flavour observables and corresponding theoretical calculations, taking into account new lower bounds on the symmetry breaking scale and the mirror quark masses from the LHC. We investigate by how much the branching ratios for a number of rare $K$ and $B$ decays are still allowed to depart from their SM values. This includes $K^+\\to\\pi^+\
In-medium kaon and antikaon properties in the quark-meson coupling model
Tsushima, K; Thomas, A W; Wright, S V
1998-01-01
The properties of the kaon, $K$, and antikaon, $\\kbar$, in nuclear medium are studied in the quark-meson coupling (QMC) model. Employing a constituent quark-antiquark (MIT bag model) picture, their excitation energies in a nuclear medium at zero momentum are calculated within mean field approximation. The scalar, and the vector mesons are assumed to couple directly to the nonstrange quarks and antiquarks in the $K$ and $\\kbar$ mesons. It is demonstrated that the $\\rho$ meson induces different mean field potentials for each member of the isodoublets, $K$ and $\\kbar$, when they are embedded in asymmetric nuclear matter. Furthermore, it is also shown that this $\\rho$ meson potential is repulsive for the $K^-$ meson in matter with a neutron excess, and renders $K^-$ condensation less likely to occur.
Quark-Lepton Mass Relation in a Realistic A4 Extension of the Standard Model
King, S F; Peinado, E; Valle, J W F
2013-01-01
We propose a realistic A4 extension of the Standard Model involving a particular quark-lepton mass relation, namely that the ratio of the third family mass to the geometric mean of the first and second family masses are equal for down-type quarks and charged leptons. This relation, which is approximately renormalization group invariant, is usually regarded as arising from the Georgi-Jarlskog relations, but in the present model there is no unification group or supersymmetry. In the neutrino sector we propose a simple modification of the so called Zee-Wolfenstein mass matrix pattern which allows an acceptable reactor angle along with a deviation of the atmospheric and solar angles from their bi-maximal values. Quark masses, mixing angles and CP violation are well described by a numerical fit.
Quark-diquark model for p(\\bar p)-p elastic scattering at high energies
Grichine, V M; Zotov, N P
2012-01-01
A model for elastic scattering of protons at high energies based on the quark-diquark representation of the proton is discussed. The predictions of the model are compared with experimental data for the differential elastic cross-sections from available databases
Quark-diquark model for p(anti p) -p elastic scattering at high energies
Energy Technology Data Exchange (ETDEWEB)
Grichine, V.M.; Starkov, N.I. [Lebedev Physical Institute, Moscow (Russian Federation); Zotov, N.P. [Lomonosov Moscow State University, Skobeltsyn Institute of Nuclear Physics, Moscow (Russian Federation)
2013-02-15
A model for elastic scattering of protons at high energies based on the quark-diquark representation of the proton is discussed. The predictions of the model are compared with experimental data for the differential elastic cross-sections from available databases. (orig.)
Jido, Daisuke
2016-01-01
The possibility to have diquark configuration in heavy baryons, such as Lambda_c and Lambda_b, is examined by a nonrelativistic potential model with a heavy quark and a light scalar diquark. Assuming that the Lambda_c and Lambda_b baryons are composed of the heavy quark and the scalar-isoscalar ud diquark, we solve the two-body Schrodinger equation with the Coulomb plus linear potential and obtain the energy spectra for the heavy baryons. Contrary to our expectation, it is found that the potential determined by the quarkonium spectra fails to reproduce the excitation spectra of the Lambda_c and Lambda_b in the quark-diquark picture, while the Lambda_c and Lambda_b spectra is reproduced with a half strength of the confinement string tension than for the quarkonium. The Xi_c excitation energy is also calculated and is found to be smaller than Lambda_c in the quark-diquark model. This is not consistent with the experimental observation. These puzzles should be solved when one takes the quark-diquark picture for ...
Energy Technology Data Exchange (ETDEWEB)
Barik, N.; Das, M.
1983-12-01
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.
S{sub 3} discrete group as a source of the quark mass and mixing pattern in 331 models
Energy Technology Data Exchange (ETDEWEB)
Carcamo Hernandez, A.E. [Universidad Tecnica Federico Santa Maria and Centro Cientifico-Tecnologico de Valparaiso, Valparaiso (Chile); Martinez, R.; Nisperuza, Jorge [Universidad Nacional de Colombia, Ciudad Universitaria, Departamento de Fisica, Bogota D.C. (Colombia)
2015-02-01
We propose a model based on the SU(3){sub C} x SU(3){sub L} x U(1){sub X} gauge symmetry with an extra S{sub 3} x Z{sub 2} x Z{sub 4} x Z{sub 12} discrete group, which successfully accounts for the SM quark mass and mixing pattern. The observed hierarchy of the SM quark masses and quark mixing matrix elements arises from the Z{sub 4} and Z{sub 12} symmetries, which are broken at a very high scale by the SU(3){sub L} scalar singlets (σ,ζ) and τ, charged under these symmetries, respectively. The Cabbibo mixing arises from the down-type quark sector whereas the up quark sector generates the remaining quark mixing angles. The obtained magnitudes of the CKM matrix elements, the CP violating phase, and the Jarlskog invariant are in agreement with the experimental data. (orig.)
Sigma terms of octet baryons in the extended chiral constituent quark model
An, C S
2014-01-01
{\\bf Background:} Quantitative insight into the respective roles played by the valence flavors and the sea quark-antiquark pairs in the baryons is crucial in deepening our comprehension of nonperturbative QCD. {\\bf Purpose:} Study the meson-baryon $\\sigma$-terms for the ground-state octet baryons $B \\equiv N,~\\Lambda,~\\Sigma,~\\Xi$. {\\bf Methods:} Within an extended chiral constituent quark model, we investigate contributions from all possible five-quark components to the $\\sigma$-terms. The probabilities of the quark-antiquark components in the baryons wave functions are calculated by taking the baryons to be admixtures of three- and five-quark components, with the relevant transitions handled {\\it via} the $^{3}P_{0}$ mechanism. {\\bf Results:} Predictions are obtained by using input parameters taken from the literature. Numerical results for the meson-nucleon and the dimensionless ${\\sigma}$-terms, $\\bar {\\sigma}_{Bl}$ and $\\bar {\\sigma}_{Bs}$, are reported. {\\bf Conclusions:} Our results turn out to be, in ...
Models for Quarks and Elementary Particles. Part III: What is the Nature of the Gravitational Field?
Directory of Open Access Journals (Sweden)
Neumann U. K. W.
2008-07-01
Full Text Available The first two parts of this article series dealt with the questions: What is a quark? and What is mass? While the present models lead to a physical idea of the mass, the geometrical theory of the general relativity only shows the effect of mass. From the physical idea of mass, from the idea of the resultant vector (EV as electric flux and from the ideas relating to the magnetic monopole (MMP it follows that the gravitational field is an electrical field. The share of the electrical gravitational flux on the entire electrical flux of a quark is determined from Newton’s empirical gravitational constant G . The superposition of the < fluxes of two quark collectives produces the gravitational force effect between two quark collectives. Gravitational fields reach infinitely far according to our current ideas. Connected with the quark oscillations hinted in the Parts I and II this results in the idea of the < - < flux spreading with infinite speed, having enormous consequences.
Quark mass and mixing in the 3-3-1 model with neutral leptons based on $D_4$ flavor symmetr
Vien, V V
2014-01-01
The $D_4$ flavor model based on $\\mathrm{SU}(3)_C \\otimes \\mathrm{SU}(3)_L \\otimes \\mathrm{U}(1)_X$ gauge symmetry is updated in which the quark mixing matrix is concentrated. After spontaneous breaking of flavor symmetry, with the constraint on Higgs VEVs in the Yukawa couplings, all of quarks have consistent masses and a small deviation from the unity is obtained at the tree-level. To obtain the quark mixing matrix consistent with experimental data in 2012, the violation terms with $\\underline{1}'$ under $D_4$ are introduced. The realistic quark mass and mixing are derived.
The Constant-Sound-Speed parameterization for NJL models of quark matter in hybrid stars
Ranea-Sandoval, Ignacio F; Orsaria, Milva G; Contrera, Gustavo A; Weber, Fridolin; Alford, Mark G
2016-01-01
The discovery of pulsars as heavy as 2 solar masses has led astrophysicists to rethink the core compositions of neutron stars, ruling out many models for the nuclear equations of state (EoS). We explore the hybrid stars that occur when hadronic matter is treated in a relativistic mean-field approximation and quark matter is modeled by three-flavor local and non-local Nambu Jona-Lasinio (NJL) models with repulsive vector interactions. The NJL models typically yield equations of state that feature a first order transition to quark matter. Assuming that the quark-hadron surface tension is high enough to disfavour mixed phases, and restricting to EoSes that allow stars to reach 2 solar masses, we find that the appearance of the quark matter core either destabilizes the star immediately (this is typical for non-local NJL models) or leads to a very short hybrid star branch in the mass-radius relation (this is typical for local NJL models). Using the Constant-Sound-Speed parametrization we can see that the reason fo...
Energy Technology Data Exchange (ETDEWEB)
Aaltonen, T.; /Helsinki Inst. of Phys.; Adelman, Jahred A.; /Chicago U., EFI; Akimoto, T.; /Tsukuba U.; Alvarez Gonzalez, B.; /Cantabria Inst. of Phys.; Amerio, S.; /INFN, Padua; Amidei, Dante E.; /Michigan U.; Anastassov, A.; /Northwestern U.; Annovi, Alberto; /Frascati; Antos, Jaroslav; /Comenius U.; Apollinari, G.; /Fermilab; Apresyan, A.; /Purdue U. /Waseda U.
2009-06-01
In a search for new phenomena in a signature suppressed in the standard model of elementary particles (SM), we compare the inclusive production of events containing a lepton ({ell}), a photon ({gamma}), significant transverse momentum imbalance (E{sub T}), and a jet identified as containing a b-quark, to SM predictions. The search uses data produced in proton-antiproton collisions at {radical}s = 1.96 TeV corresponding to 1.9 fb{sup -1} of integrated luminosity taken with the CDF detector at the Fermilab Tevatron. We find 28 {ell}{gamma}bE{sub T} events versus an expectation of 31.0{sub -3.5}{sup +4.1} events. If we further require events to contain at least three jets and large total transverse energy, simulations predict that the largest SM source is top-quark pair production with an additional radiated photon, t{bar t} + {gamma}. In the data we observe 16 t{bar t}{gamma} candidate events versus an expectation from non-top-quark SM sources of 11.2{sub -2.1}{sup +2.3}. Assuming the difference between the observed number and the predicted non-top-quark total is due to SM top quark production, we estimate the t{bar t} cross section to be 0.15 {+-} 0.08 pb.
Top Quark Mass in the Condensate Model and the Possibility of Colored Bosons
Kundu, Anirban; de, Triptesh; Dutta-Roy, Binayak
The dynamical electroweak symmetry breaking of the Standard Model triggered by a top quark condensate (induced by an effective strong interaction, associated with a highenergy scale, of the form gt bar ψ Li tR bar tR ψ Li ) usually requires an embarrassingly large top quark mass. A suggestion that this problem could be avoided through the introduction of an additional interaction gt' bar ψ LiP ( {AJI } ; )PQ tRQ bar tRS ( {AIJ } ; )STψ LiT } (where AJI are SU(3)c generators á la Okubo) is analyzed using the renormalization group approach. The mass of the top quark and the concomitant emergence of colored composite bosons is discussed.
Strong decays of N~*(1535) in an extended chiral quark model
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
The strong decays of the N*(1535) resonance are investigated in an extended chiral quark model by including the low-lying qqqqq components in addition to the qqq component.The results show that these five-quark components in N*(1535) contribute significantly to the N*(1535)→ Nπ and N*(1535) → Nη decays.The contributions to the Nη decay come from both the lowest energy and the next-to-lowest energy five-quarks components,while the contributions to the Nπ decay come from only the latter one.Taking these contributions into account,the description for the strong decays of N*(1535) is improved,especially for the puzzling large ratio of the decays to Nη and Nπ.
X(5568) as a {su}\\bar{d}\\bar{b} tetraquark in a simple quark model
Stancu, Fl
2016-10-01
The S-wave eigenstates of tetraquarks of type {su}\\bar{d}\\bar{b} with J P = 0+, 1+ and 2+ are studied within a simple quark model with chromomagnetic interaction and effective quark masses extracted from meson and baryon spectra. It is tempting to see if this spectrum can accommodate the new narrow structure X(5568), observed by the DØ Collaboration, but not confirmed by the LHCb Collaboration. If it exists, such a tetraquark is a system with four different flavors and its study can improve our understanding of multiquark systems. The presently calculated mass of X(5568) agrees quite well with the experimental value of the DØ Collaboration. Predictions are also made for the spectrum of the charmed partner {su}\\bar{d}\\bar{c}. However we are aware of the difficulty of extracting effective quark masses, from mesons and baryons, to be used in multiquark systems.
Nuclear symmetry energy in a modified quark-meson coupling model
Mishra, R. N.; Sahoo, H. S.; Panda, P. K.; Barik, N.; Frederico, T.
2015-10-01
We study nuclear symmetry energy and the thermodynamic instabilities of asymmetric nuclear matter in a self-consistent manner by using a modified quark-meson coupling model where the confining interaction for quarks inside a nucleon is represented by a phenomenologically averaged potential in an equally mixed scalar-vector harmonic form. The nucleon-nucleon interaction in nuclear matter is then realized by introducing additional quark couplings to σ ,ω , and ρ mesons through mean-field approximations. We find an analytic expression for the symmetry energy Esym as a function of its slope L . Our result establishes a linear correlation between L and Esym. We also analyze the constraint on neutron star radii in (p n ) matter with β equilibrium.
Model Independent Framework for Analysis of Scenarios with Multiple Heavy Extra Quarks
Barducci, Daniele; Buchkremer, Mathieu; Cacciapaglia, Giacomo; Deandrea, Aldo; De Curtis, Stefania; Marrouche, Jad; Moretti, Stefano; Panizzi, Luca
2014-01-01
In this paper we present an analysis strategy and a dedicated tool to determine the exclusion confidence level for any scenario involving multiple heavy extra quarks with generic decay channels, as predicted in several extensions of the Standard Model. We have created, validated and used a software package, called XQCAT (eXtra Quark Combined Analysis Tool), which is based on publicly available experimental data from direct searches for top partners and from Supersymmetry inspired searches. The code will soon be publicly available and will be upgraded to include data from new searches. By means of this code, we recast the limits from CMS on new heavy extra quarks considering a complete set of decay channels. The resulting exclusion confidence levels are presented for some simple scenarios with multiple states and general coupling assumptions. Highlighting the importance of combining multiple topology searches to obtain accurate re-interpretations of the existing searches, we discuss the reach of the SUSY analy...
Radiative generation of quark masses and mixing angles in the two Higgs doublet model
Energy Technology Data Exchange (ETDEWEB)
Ibarra, Alejandro [Physik-Department T30d, Technische Universität München, James-Franck-Straße, 85748 Garching (Germany); Solaguren-Beascoa, Ana [Physik-Department T30d, Technische Universität München, James-Franck-Straße, 85748 Garching (Germany); Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, 80805 München (Germany)
2014-09-07
We present a framework to generate the quark mass hierarchies and mixing angles by extending the Standard Model with one extra Higgs doublet. The charm and strange quark masses are generated by small quantum effects, thus explaining the hierarchy between the second and third generation quark masses. All the mixing angles are also generated by small quantum effects: the Cabibbo angle is generated at zeroth order in perturbation theory, while the remaining off-diagonal entries of the Cabibbo–Kobayashi–Maskawa matrix are generated at first order, hence explaining the observed hierarchy |V{sub ub}|,|V{sub cb}|≪|V{sub us}|. The values of the radiatively generated parameters depend only logarithmically on the heavy Higgs mass, therefore this framework can be reconciled with the stringent limits on flavor violation by postulating a sufficiently large new physics scale.
Ramalho, G
2012-01-01
We study the $\\gamma^\\ast \\Lambda \\to \\Sigma^0$ transition form factors by applying the covariant spectator quark model. Using the parametrization for the baryon core wave functions as well as for the pion cloud dressing obtained in a previous work, we calculate the dependence on the momentum transfer squared, $Q^2$, of the electromagnetic transition form factors. The magnetic form factor is dominated by the valence quark contributions. The final result for the transition magnetic moment, a combination of the quark core and pion cloud effects, turns out to give a value very close to the data. The pion cloud, although small, makes the result towards the data. It is also predicted that small but nonzero values for the electric form factor in the finite $Q^2$ region, as a consequence of the pion cloud dressing.
Radiative generation of quark masses and mixing angles in the two Higgs doublet model
Directory of Open Access Journals (Sweden)
Alejandro Ibarra
2014-09-01
Full Text Available We present a framework to generate the quark mass hierarchies and mixing angles by extending the Standard Model with one extra Higgs doublet. The charm and strange quark masses are generated by small quantum effects, thus explaining the hierarchy between the second and third generation quark masses. All the mixing angles are also generated by small quantum effects: the Cabibbo angle is generated at zeroth order in perturbation theory, while the remaining off-diagonal entries of the Cabibbo–Kobayashi–Maskawa matrix are generated at first order, hence explaining the observed hierarchy |Vub|,|Vcb|≪|Vus|. The values of the radiatively generated parameters depend only logarithmically on the heavy Higgs mass, therefore this framework can be reconciled with the stringent limits on flavor violation by postulating a sufficiently large new physics scale.
Radiative Generation of Quark Masses and Mixing Angles in the Two Higgs Doublet Model
Ibarra, Alejandro
2014-01-01
We present a framework to generate the quark mass hierarchies and mixing angles by extending the Standard Model with one extra Higgs doublet. The charm and strange quark masses are generated by small quantum effects, thus explaining the hierarchy between the second and third generation quark masses. All the mixing angles are also generated by small quantum effects: the Cabibbo angle is generated at zero-th order in perturbation theory, while the remaining off-diagonal entries of the Cabibbo-Kobayashi-Maskawa matrix are generated at first order, hence explaining the observed hierarchy $|V_{ub}|,|V_{cb}|\\ll |V_{us}|$. The values of the radiatively generated parameters depend only logarithmically on the heavy Higgs mass, therefore this framework can be reconciled with the stringent limits on flavor violation by postulating a sufficiently large new physics scale.
Excited State Contributions to the Heavy Baryon Fragmentation Functions in a Quark-Diquark Model
Adamov, A D; Goldstein, Gary R.
2001-01-01
Spin dependent fragmentation functions for heavy flavor quarks to fragment into heavy baryons are calculated in a quark-diquark model. The production of intermediate spin 1/2 and 3/2 excited states is explicity included. The resulting $\\Lambda_b$ production rate and polarization at LEP energies are in agreement with experiment. The $\\Lambda_c$ and $\\Xi_c$ functions are also obtained. The spin independent $f_1(z)$ is compared to data. The integrated values for production rates agree with the data.
Nucleon and gamma N -> Delta lattice form factors in a constituent quark model
Ramalho, G
2008-01-01
A covariant quark model, based both on the spectator formalism and on Vector Meson Dominance, and previously calibrated by the physical data, is here extended to the unphysical region of the lattice data by means of one single extra adjustable parameter - the constituent quark mass in the chiral limit. We calculated the Nucleon (N) and the Gamma N -> Delta form factors in the universe of values for that parameter described by quenched lattice QCD. A qualitative description of the Nucleon and Gamma N -> Delta form factors lattice data is achieved for light pion masses.
Quark matter under strong magnetic fields in the Nambu--Jona-Lasinio Model
Peres-Menezes, D; Avancini, S S; Martinez, A Perez; Providência, C
2008-01-01
In the present work we use the large-$N_c$ approximation to investigate quark matter described by the SU(2) Nambu--Jona-Lasinio model subject to a strong magnetic field. The Landau levels are filled in such a way that usual kinks appear in the effective mass and other related quantities. $\\beta$-equilibrium is also considered and the macroscopic properties of a magnetar described by this quark matter is obtained. Our study shows that the magnetar masses and radii are larger if the magnetic field increases but only very large fields ($\\ge 10^{18}$ G) affect the EoS in a non negligible way.
Study of J／Ψ（Ψ′）→YY－ Decays in Quark Model
Institute of Scientific and Technical Information of China (English)
PINGRong-Gang; JIANGHuan-Qing
2003-01-01
Bxclusive decays J/Ψ(Ψ′)→YY-(Y=∧,∑0,≡-) are studied in the quark model by combining thes tructure of hyperons in the transition. The branching ratios are evaluated contrastively by adopting different hyperon wavefunctions, SU(6) basis, and uds basis, which account for SU(3) f breaking, and the results show that the different description of quark mass breaking plays an important role in the evaluation of the decay width for processes J/Ψ(Ψ′)→YY-.
Quark-Gluon Plasma in a Bag Model with a Soft Surface
Jacobsen, Rafael B.; Marranghello, Guilherme F.; Vasconcellos, César A. Z.; Mesquita, Alexandre
We analyze the implications of quantum hadrodynamics (QHD) and quantum chromodynamics (QCD) to model, respectively, two distinct phases of nuclear matter, a baryon-meson phase and a quark-gluon phase. We develop an equation of state (EoS) in the framework of a quark-meson coupling model for the hadron-meson phase using a new version of the fuzzy bag model with scalar-isoscalar, vector-isoscalar and vector-isovector meson-quark couplings and leptonic degrees of freedom as well as the constrains from chemical equilibrium, baryon number and electric charge conservation. We model the EoS for the QGP phase for asymptotically free massless quarks and gluons using the MIT approach and a temperature and baryon chemical potential dependent bag constant, B(T,μ), which allows an isentropic equilibrium phase transition from a QGP to a hadron gas as determined by thermodynamics. Our predictions yield the EoS and static global properties of neutron stars and protoneutron stars at low and moderate values of temperature. Our results are slightly modified in comparison to predictions based on the standard MIT bag model with a constant bag pressure B.
Finite temperature quantum correlations in su(2)(c) quark states and quantum spin models
Hamieh, S; Tawfik, A
2005-01-01
The entanglement at finite temperatures is analyzed by using thermal models for colored quarks making tip the hadron physical states. We have found that these quantum correlations entirely vanish at T-c >= m(q)/ln(1.5). For temperatures larger than T-c the correlations are classical. We have also wo
Polarized antiquark distributions from chiral quark-soliton model summary of the results
Göke, K; Polyakov, M V; Urbano, D
2000-01-01
In these short notes we present a parametrization of the results obtained in the chiral quark-soliton model for polarized antiquark distributions $\\Delta\\bar u$, $\\Delta\\bar d$ and $\\Delta\\bar s$ at a low normalization point around mu=0.6 GeV.
Nucleon electromagnetic form factors in a relativistic quark model with chiral symmetry
Energy Technology Data Exchange (ETDEWEB)
Barik, N.; Das, M.
1987-05-01
The nucleon electromagnetic form factors are computed in an independent quark model based on the Dirac equation. Corrections for centre-of-mass motion and pion-cloud effects are incorporated. Results for static quantities are in reasonable agreement with the experimental data.
Inverse Magnetic Catalysis in hot quark matter within (P)NJL models
Ferreira, M; Providência, C; Lourenço, O; Frederico, T
2015-01-01
Apart from Magnetic Catalysis at low temperatures, recent LQCD studies have shown the opposite effect at temperatures near the transition region: instead of enhancing, the magnetic field suppresses the quark condensates (Inverse Magnetic Catalysis). In this paper, two approaches are discussed within NJL-type models with Polyakov Loop that reproduce both effects.
Light-Front Quark Model Analysis of Meson-Photon Transition Form Factor
Choi, Ho-Meoyng
2016-01-01
We discuss $(\\pi^0,\\eta,\\eta')\\to\\gamma^*\\gamma$ transition form factors using the light-front quark model. Our discussion includes the analysis of the mixing angles for $\\eta-\\eta'$. Our results for $Q^2 F_{(\\pi^0,\\eta,\\eta')\\to\\gamma^*\\gamma}(Q^2)$ show scaling behavior for high $Q^2$ consistent with pQCD predictions.
QCD equations of state and the quark-gluon plasma liquid model
Letessier, Jean; Rafelski, Johann
2003-03-01
Recent advances in the study of equations of state of thermal lattice quantum chromodynamics obtained at nonzero baryon density allow validation of the quark-gluon plasma (QGP) liquid model equations of state (EOS). We study here the properties of the QGP-EOS near to the phase transformation boundary at finite baryon density and show a close agreement with the lattice results.
Semileptonic decays of $\\Lambda_c$ baryons in the relativistic quark model
Faustov, R N
2016-01-01
Motivated by recent experimental progress in studying weak decays of the $\\Lambda_c$ baryon we investigate its semileptonic decays in the framework of the relativistic quark model based on the quasipotential approach and QCD. The form factors of the $\\Lambda_c\\to \\Lambda l\
Nucleon-Nucleon Phase Shifts in the Extended Quark-Delocalization Colour-Screening Model
Institute of Scientific and Technical Information of China (English)
LU Xi-Feng; PING Jia-Lun; WANG Fan
2003-01-01
An alternative method is applied to the study of nucleon-nucleon scattering phase shifts within the framework of the extended quark demoralization colour-screening model, in which the one-pion exchange with short-range cutoff is included.
From Chiral quark dynamics with Polyakov loop to the hadron resonance gas model
Arriola, E Ruiz; Salcedo, L L
2012-01-01
Chiral quark models with Polyakov loop at finite temperature have been often used to describe the phase transition. We show how the transition to a hadron resonance gas is realized based on the quantum and local nature of the Polyakov loop.
Quark-Antiquark and Diquark Condensates in Vacuum in a 2D Two-Flavor Gross-Neveu Model
Institute of Scientific and Technical Information of China (English)
ZHOU Bang-Rong
2007-01-01
The analysis based on the renormalized effective potential indicates that, similar to in the 4D two-flavor Nambu-Jona-Lasinio (NJL) model, in a 2D two-flavor Gross-Neveu model, the interplay between the quark-antiquark and the diquark condensates in vacuum also depends on Gs/Hs, the ratio of the coupling constants in scalar quark antiquark and scalar diquark channel. Only the pure quark-antiquark condensates exist if Gs/Hs ＞ 2/3, which is just the ratio of the color numbers of the quarks participating in the diquark and quark-antiquark condensates. The two condensates will coexist if 0 ＜ Gs/Hs ＜ 2/3. However, different from the 4D NJL model, the pure diquark condensates arise only at Gs/Hs = 0 and are not in a possibly finite region of Gs/Hs below 2/3.
A chiral matrix model of the semi-Quark Gluon Plasma in QCD
Pisarski, Robert D
2016-01-01
A chiral matrix model applicable to QCD with 2+1 flavors is developed. This requires adding a SU(3)_L x SU(3)_R x Z(3)_A nonet of scalar fields, with both parities, and coupling these to quarks through a Yukawa coupling, y. Treating the scalar fields in mean field approximation, the effective Lagrangian is computed by integrating out quarks to one loop order. In addition to the usual symmetry breaking term, linear in the current quark mass m_qk, at a nonzero temperature T it is necessary to add a new term, ~ m_qk T^2. The parameters of the gluon part of the matrix model, including especially the deconfining transition temperature T_d = 270 MeV, are identical to that for the pure glue theory without quarks. The parameters in the chiral matrix model are fixed by the values, at zero temperature, of the pion decay constant the masses of the pions, kaons, eta, and eta'. The temperature for the chiral crossover at T_chi = 155 MeV is determined by adjusting the Yukawa coupling y. We find reasonable agreement with th...
Equation of State for a Quark Gluon Plasma in the Fuzzy Bag Model
Jacobsen, R. B.; Vasconcellos, C. A. Z.; Bodmann, Bardo E. J.; Dillig, Manfred
2004-12-01
We study two distinct phases of nuclear matter, a baryon-meson phase and a quark-gluon phase (QGP). For the baryon-meson phase we develop an equation of state (EoS) using a quark-meson formulation based on a new version of the fuzzy bag model with scalar-isoscalar, vector-isoscalar and vector-isovector meson-quark couplings and leptonic degrees of freedom as well as the constraints of chemical equilibrium, baryon number and electric charge conservation. For the QGP phase we model an EoS for asymptotically free massless quarks and gluons using the MIT approach and a temperature and baryon chemical potential dependent bag constant, B(T,μ), which allows an isentropic equilibrium phase transition from a QGP to a hadron gas. Our main results indicate the EoS and static global properties of neutron stars and protoneutron stars at low and moderate values of temperature are slightly modified in comparison to the predictions based on the MIT bag model with a constant B.
Real and virtual photon emission within effective quark-meson models
Energy Technology Data Exchange (ETDEWEB)
Wunderlich, Falk; Kaempfer, Burkhard [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Institut fuer Theoretische Physik, TU Dresden (Germany)
2014-07-01
Certain aspects of the behaviour of strongly interacting matter can be understood in terms of effective models. Among such models are the quark-meson models. With a suitable choice of parameters and field content their phase diagram exhibits a 1st order phase transition that terminates in a critical point at nonzero chemical potential. Including the electromagnetic sector we investigate the dependence of the real and virtual photon rates on temperature and chemical potential with emphasis on peculiarities near the critical point.
Exclusive Rare B ( s, c) Decays in Light-Front Quark Model
Choi, Ho-Meoyng
2013-03-01
We investigate the exclusive rare {B_sto (K,η^{(')})(ν_{ell}bar{ν_{ell}}, ell^+ell^-)} and {B_cto D_{(s)}(ν_{ell}bar{ν_{ell}}, ell^+ell^-)} ( ℓ = e, μ, τ) decays within the standard model and the light-front quark model constrained by the variational principle for the QCD motivated effective Hamiltonian. The branching ratios and the longitudinal lepton polarization asymmetries are calculated and compared with other theoretical model predictions.
Explanation of the masses of quarks and leptons in a supersymmetric preon model
Energy Technology Data Exchange (ETDEWEB)
Jongbae Kim [Department of Physics, University of Maryland, College Park, MD 20742 (United States); Research Department, ETRI, Yusong PO Box 106, Taejon 305-600 (Korea, Republic of)
1998-10-01
We have studied whether the radiative effects including gauge and Yukawa interaction corrections can improve the phenomenological consequences on the masses of quarks and leptons in the supersymmetric preon model. Our study shows that pure renormalization effects in the region from the metacolour scale to the electroweak scale produce quark-lepton distinction within a given family. They cannot, however, produce the desired up-down distinction or the expected quark-lepton asymmetry in the effective hierarchy parameter p{sup 2}/4 of the up, down and lepton sectors. It also shows that the pure radiative corrections cannot explain the 'fine structure' effects exhibited by ((m{sub s})/m{sub c})1 GeV > ((m{sub b})/m{sub s})L GeV > ((m{sub r})/m{sub {mu}})1 GeV. These lead us to conclude that the symmetry structure of the preon theory cannot strictly respect left-right, up-down and quark-lepton symmetries near and below the Planck scale. This subsequently implies the SU(3){sup C}xSU(2){sub L}xU(1){sub r} symmetry both as regards unification of couplings near the Planck scale in the model and as regards its possible origin from a superstring theory. (author)
Explanation of the masses of quarks and leptons in a supersymmetric preon model
Kim, Jongbae
1998-10-01
We have studied whether the radiative effects including gauge and Yukawa interaction corrections can improve the phenomenological consequences on the masses of quarks and leptons in the supersymmetric preon model. Our study shows that pure renormalization effects in the region from the metacolour scale to the electroweak scale produce quark-lepton distinction within a given family. They cannot, however, produce the desired up-down distinction or the expected quark-lepton asymmetry in the effective hierarchy parameter 0954-3899/24/10/006/img1 of the up, down and lepton sectors. It also shows that the pure radiative corrections cannot explain the `fine structure' effects exhibited by 0954-3899/24/10/006/img2. These lead us to conclude that the symmetry structure of the preon theory cannot strictly respect left-right, up-down and quark-lepton symmetries near and below the Planck scale. This subsequently implies the 0954-3899/24/10/006/img3 symmetry both as regards unification of couplings near the Planck scale in the model and as regards its possible origin from a superstring theory.
The Nucleon-Nucleon Interaction in a Chiral Constituent Quark Model
Stancu, F; Glozman, L Ya; Stancu, Fl.
1997-01-01
We study the short-range nucleon-nucleon interaction in a chiral constituent quark model by diagonalizing a Hamiltonian comprising a linear confinement and a Goldstone boson exchange interaction between quarks. The six-quark harmonic oscillator basis contains up to two excitation quanta. We show that the highly dominant configuration is $\\mid s^4p^2[42]_O [51]_{FS}>$ due to its specific flavour-spin symmetry. Using the Born-Oppenheimer approximation we find a strong effective repulsion at zero separation between nucleons in both $^3S_1$ and $^1S_0$ channels. The symmetry structure of the highly dominant configuration implies the existence of a node in the S-wave relative motion wave function at short distances. The amplitude of the oscillation of the wave function at short range will be however strongly suppressed. We discuss the mechanism leading to the effective short-range repulsion within the chiral constituent quark model as compared to that related with the one-gluon exchange interaction.
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.
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.)
Jido, Daisuke; Sakashita, Minori
2016-08-01
The possibility of having a diquark configuration in heavy baryons, such as Λ and Λ, is examined by a nonrelativistic potential model with a heavy quark and a light scalar diquark. Assuming that the Λ and Λ baryons are composed of the heavy quark and the point-like scalar-isoscalar ud diquark, we solve the two-body Schrödinger equation with the Coulomb plus linear potential and obtain the energy spectra for the heavy baryons. Contrary to our expectation, it is found that the potential determined by the quarkonium spectra fails to reproduce the excitation spectra of the Λ and Λ in the quark-diquark picture, while the Λ and Λ spectra are reproduced with half the strength of the confinement string tension than for the quarkonium. The finite size effect of the diquark is also examined and it is found that the introduction of a finite size diquark would resolve the failure of the spectrum reproduction. The Ξ excitation energy is also calculated and is found to be smaller than Λ in the quark-diquark model. This is not consistent with experimental observations.
An independent quark model study of weak leptonic decays of pseudoscalar mesons
Jena, S. N.; Nanda, P. K.; Sahoo, S.; Panda, S.
2015-05-01
An independent quark model with a relativistic power-law potential is used to study the weak leptonic decays of light and heavy pseudoscalar mesons. The partial decay width and the decay constant for the weak leptonic decay are derived from the quark-antiquark momentum distribution amplitude which is obtained from the bound quark eigenfunction with the assumption of a strong correlation existing between quark-antiquark momenta inside the decaying meson in its rest frame. The model parameters are first determined from the application of the model to study the ground state hyperfine splitting of ρ, K, D, Ds, B, Bs and Bc mesons. The same model with no adjustable parameters is then used to evaluate the decay constants fM and the decay widths of pseudoscalar mesons. The model predictions agree quite well with the available experimental data as well as with those of several other models. The decay constant for pion and kaon are obtained as fπ = 132 MeV and fk = 161 MeV which closely agree with experimental values. But in case of heavier mesons for which experimental data are not yet available, the present model gives its predictions as fBC > fBS > fB, fDS > fD, fD > fB and fπ > fB which are in conformity with most of other model predictions. The model predictions of the corresponding decay widths and the branching ratios for the (l\\bar {ν }l) and (τ \\bar {ν }τ ) decay modes are in close agreement with the available experimental data.
Thermo-magnetic effects in quark matter: Nambu-Jona-Lasinio model constrained by lattice QCD
Farias, R L S; Avancini, S S; Pinto, M B; Krein, G
2016-01-01
The phenomenon of inverse magnetic catalysis of chiral symmetry in QCD predicted by lattice simulations can be reproduced within the Nambu-Jona-Lasinio model if the coupling G of the model decreases with the strength B of the magnetic field and temperature T. The thermo-magnetic dependence of G(B,T) is obtained by fitting recent lattice QCD predictions for the chiral transition order parameter. Different thermodynamic quantities of magnetized quark matter evaluated with a G(B, T) are compared with the ones obtained at constant coupling G. The model with a G(B,T) predicts a more dramatic chiral transition as the field intensity increases. In addition, the pressure and magnetization always increase with B for a given temperature. Being parametrized by four magnetic field dependent coefficients and having a rather simple exponential thermal dependence our accurate ansatz for the running coupling can be easily implemented to improve typical model applications to magnetized quark matter.
Propagation of cosmic rays through the atmosphere in the quark-gluon strings model
Erlykin, A. D.; Krutikova, N. P.; Shabelski, Y. M.
1985-01-01
The quark-gluon strings model succeeds in the description of multiple hadron production in the central rapidity region of nucleon-nucleon interctions. This model was developed for hadron-nucleus interactions and used for calculation of the cosmic ray propagation through the atmosphere. It is shown that at energies 10 to the 11th power to the 12th power eV, this model gives a satisfactory description of experimental data. But with the increase of the energy up to approximately 10 to the 14th power eV, results of calculations and of experiments begin to differ and this difference rises with the energy. It may indicate that the scaling violation in the fragmentation region of inclusive spectra for hadron-nucleus interactions is stronger than in the quark-gluon strings model.
Nucleon Properties at Finite Temperature in the Extended Quark-Sigma Model
Abu-Shady, M
2014-01-01
Hadron properties are studied at hot medium using the quark sigma model. The quark sigma model is extended to include eighth-order of mesonic interactions based on some aspects of quantum chromodynamic (QCD) theory. The extended effective potential tends to the original effective potential when the coupling between the higher order mesonic interactions equal to zero. The field equations have been solved in the mean-field approximation by using the extended iteration method. We found that the nucleon mass increases with increasing temperature and the magnetic moments of proton and neutron increase with increasing temperature. A comparison is presented with recent previous works and other models. We conclude that higher-order mesonic interactions play an important role in changing the behavior of nucleon properties at finite temperature. In addition, the deconfinement phase transition is satisfied in the present model.
Thermo-magnetic effects in quark matter: Nambu-Jona-Lasinio model constrained by lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Farias, Ricardo L.S. [Universidade Federal de Santa Maria, Departamento de Fisica, Santa Maria, RS (Brazil); Kent State University, Physics Department, Kent, OH (United States); Timoteo, Varese S. [Universidade Estadual de Campinas (UNICAMP), Grupo de Optica e Modelagem Numerica (GOMNI), Faculdade de Tecnologia, Limeira, SP (Brazil); Avancini, Sidney S.; Pinto, Marcus B. [Universidade Federal de Santa Catarina, Departamento de Fisica, Florianopolis, Santa Catarina (Brazil); Krein, Gastao [Universidade Estadual Paulista, Instituto de Fisica Teorica, Sao Paulo, SP (Brazil)
2017-05-15
The phenomenon of inverse magnetic catalysis of chiral symmetry in QCD predicted by lattice simulations can be reproduced within the Nambu-Jona-Lasinio model if the coupling G of the model decreases with the strength B of the magnetic field and temperature T. The thermo-magnetic dependence of G(B, T) is obtained by fitting recent lattice QCD predictions for the chiral transition order parameter. Different thermodynamic quantities of magnetized quark matter evaluated with G(B, T) are compared with the ones obtained at constant coupling, G. The model with G(B, T) predicts a more dramatic chiral transition as the field intensity increases. In addition, the pressure and magnetization always increase with B for a given temperature. Being parametrized by four magnetic-field-dependent coefficients and having a rather simple exponential thermal dependence our accurate ansatz for the coupling constant can be easily implemented to improve typical model applications to magnetized quark matter. (orig.)
Constituent Quarks and Gluons, Polyakov loop and the Hadron Resonance Gas Model
Megias, E; Salcedo, L L
2013-01-01
Based on first principle QCD arguments, it has been argued in arXiv:1204.2424[hep-ph] that the vacuum expectation value of the Polyakov loop can be represented in the hadron resonance gas model. We study this within the Polyakov-constituent quark model by implementing the quantum and local nature of the Polyakov loop hep-ph/0412308, hep-ph/0607338. The existence of exotic states in the spectrum is discussed.
Some Possible Grand Unified Preon Models with Light Quarks and Leptons
Du, Dongsheng; Lu, Gongru
Three grand unified preon models with light quarks and leptons are presented. All these models have natural family structure at the composite level. One of them can give a very low metacolor scale, ΛMC~3×104 GeV. It is argued that the best choice for a metacolor group is SU(4) and that for a unification group it is SU(9).
Extension of Standard Model with a Complex Singlet and Iso-Doublet Vector Quarks
Darvishi, Neda
2017-07-01
In this paper the extension of the SM by a neutral complex scalar singlet with a nonzero vacuum expectation value and a heavy vector quark pair is considered. This model provides an extra source of spontaneous CP violation. The focus of this article is to obtain the rate of baryon number generation. We show that the considered model provides a strong enough first-order electroweak phase transition to suppress the baryon-violating sphaleron process.
Constituent Quarks and Gluons, Polyakov loop and the Hadron Resonance Gas Model *,**
Directory of Open Access Journals (Sweden)
Megías E.
2014-03-01
Full Text Available Based on first principle QCD arguments, it has been argued in [1] that the vacuum expectation value of the Polyakov loop can be represented in the hadron resonance gas model. We study this within the Polyakov-constituent quark model by implementing the quantum and local nature of the Polyakov loop [2, 3]. The existence of exotic states in the spectrum is discussed.
Quark model with chiral-symmetry breaking and confinement in the Covariant Spectator Theory
Energy Technology Data Exchange (ETDEWEB)
Biernat, Elmer P. [CFTP, Instituto Superior TÃ©cnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; Pena, Maria Teresa [CFTP, Instituto Superior TÃ©cnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; Departamento de FÃsica, Instituto Superior TÃ©cnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; Ribiero, Jose' Emilio F. [CeFEMA, Instituto Superior TÃ©cnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; Stadler, Alfred [Departamento de FÃsica, Universidade de Ãvora, 7000-671 Ãvora, Portugal; Gross, Franz L. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
2016-03-01
We propose a model for the quark-antiquark interaction in Minkowski space using the Covariant Spectator Theory. We show that with an equal-weighted scalar-pseudoscalar structure for the confining part of our interaction kernel the axial-vector Ward-Takahashi identity is preserved and our model complies with the Adler-zero constraint for pi-pi-scattering imposed by chiral symmetry.
Polyakov-Quark-Meson-Diquark Model for two-color QCD
Strodthoff, Nils
2013-01-01
We present an update on the phase diagram of two-color QCD from a chiral effective model approach based on a quark-meson-diquark model using the Functional Renormalization Group (FRG). We discuss the impact of perturbative UV contributions, the inclusion of gauge field dynamics via a phenomenological Polyakov loop potential, and the impact of matter backcoupling on the gauge sector. The corresponding phase diagram including these effects is found to be in qualitative agreement with recent lattice investigations.
Relativistic Effects in a QCD Inspired quark model and the necessity of a short distance scale
Pathak, Krishna Kingkar
2010-01-01
We study the masses and decay constants of heavy light flavoured mesons in a QCD Inspired Quark model. We modify the relativistic correction procedure by introducing a short distance scale r0 in analogy with relativistic Hydrogen atom and estimate the values of masses and decay constants of heavy-light mesons. Necessity of a short distance scale r0 \\leq 10-3 - 10-5 fm in the model is indicated. Keywords: heavy- light mesons, masses, decay constants
Quark flavour observables in the Littlest Higgs model with T-parity after LHC Run 1.
Blanke, Monika; Buras, Andrzej J; Recksiegel, Stefan
2016-01-01
The Littlest Higgs model with T-parity (LHT) belongs to the simplest new physics scenarios with new sources of flavour and CP violation. The latter originate in the interactions of ordinary quarks and leptons with heavy mirror quarks and leptons that are mediated by new heavy gauge bosons. Also a heavy fermionic top partner is present in this model which communicates with the SM fermions by means of standard [Formula: see text] and [Formula: see text] gauge bosons. We present a new analysis of quark flavour observables in the LHT model in view of the oncoming flavour precision era. We use all available information on the CKM parameters, lattice QCD input and experimental data on quark flavour observables and corresponding theoretical calculations, taking into account new lower bounds on the symmetry breaking scale and the mirror quark masses from the LHC. We investigate by how much the branching ratios for a number of rare K and B decays are still allowed to depart from their SM values. This includes [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text]. Taking into account the constraints from [Formula: see text] processes, significant departures from the SM predictions for [Formula: see text] and [Formula: see text] are possible, while the effects in B decays are much smaller. In particular, the LHT model favours [Formula: see text], which is not supported by the data, and the present anomalies in [Formula: see text] decays cannot be explained in this model. With the recent lattice and large N input the imposition of the [Formula: see text] constraint implies a significant suppression of the branching ratio for [Formula: see text] with respect to its SM value while allowing only for small modifications of [Formula: see text]. Finally, we investigate how the LHT physics could be distinguished from other models by means of indirect measurements and
Quark flavour observables in the Littlest Higgs model with T-parity after LHC Run 1
Blanke, Monika; Buras, Andrzej J.; Recksiegel, Stefan
2016-04-01
The Littlest Higgs model with T-parity (LHT) belongs to the simplest new physics scenarios with new sources of flavour and CP violation. The latter originate in the interactions of ordinary quarks and leptons with heavy mirror quarks and leptons that are mediated by new heavy gauge bosons. Also a heavy fermionic top partner is present in this model which communicates with the SM fermions by means of standard W^± and Z^0 gauge bosons. We present a new analysis of quark flavour observables in the LHT model in view of the oncoming flavour precision era. We use all available information on the CKM parameters, lattice QCD input and experimental data on quark flavour observables and corresponding theoretical calculations, taking into account new lower bounds on the symmetry breaking scale and the mirror quark masses from the LHC. We investigate by how much the branching ratios for a number of rare K and B decays are still allowed to depart from their SM values. This includes K^+→ π ^+ν bar{ν }, KL→ π ^0ν bar{ν }, K_L→ μ ^+μ ^-, B→ X_sγ , B_{s,d}→ μ ^+μ ^-, B→ K^{(*)}ℓ ^+ℓ ^-, B→ K^{(*)}ν bar{ν }, and \\varepsilon '/\\varepsilon . Taking into account the constraints from Δ F=2 processes, significant departures from the SM predictions for K^+→ π ^+ν bar{ν } and KL→ π ^0ν bar{ν } are possible, while the effects in B decays are much smaller. In particular, the LHT model favours B(Bs→ μ ^+μ ^-) ≥ B(Bs→ μ ^+μ ^-)_SM, which is not supported by the data, and the present anomalies in B→ K^{(*)}ℓ ^+ℓ ^- decays cannot be explained in this model. With the recent lattice and large N input the imposition of the \\varepsilon '/\\varepsilon constraint implies a significant suppression of the branching ratio for KL→ π ^0ν bar{ν } with respect to its SM value while allowing only for small modifications of K^+→ π ^+ν bar{ν }. Finally, we investigate how the LHT physics could be distinguished from other models by means of
Strange matter equation of state in the quark mass-density-dependent model
Energy Technology Data Exchange (ETDEWEB)
Benvenuto, O.G. (Facultad de Ciencias Astronomicas y Geofisicas, Universidad Nacional de La Plata, Paseo del Bosque S/N, 1900 La Plata (Argentina)); Lugones, G. (Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 1900 La Plata (Argentina))
1995-02-15
We study the properties and stability of strange matter at [ital T]=0 in the quark mass-density-dependent model for noninteracting quarks. We found a wide stability window'' for the values of the parameters ([ital C],[ital M][sub [ital s]0]) and the resulting equation of state at low densities is stiffer than that of the MIT bag model. At high densities it tends to the ultrarelativistic behavior expected because of the asymptotic freedom of quarks. The density of zero pressure is near the one predicted by the bag model and [ital not] shifted away as stated before; nevertheless, at these densities the velocity of sound is [approx]50% larger in this model than in the bag model. We have integrated the equations of stellar structure for strange stars with the present equation of state. We found that the mass-radius relation is very much the same as in the bag model, although it extends to more massive objects, due to the stiffening of the equation of state at low densities.
Glueball Decay in the Witten-Sakai-Sugimoto Model and Finite Quark Masses
Brünner, Frederic
2015-01-01
We discuss recent results on the calculation of glueball decay rates in the Witten-Sakai-Sugimoto model, which favor the $f_0(1710)$ meson as a glueball candidate. The flavor asymmetric decay of $f_0(1710)$ is frequently attributed to a putative chiral suppression in glueball decays, which is however questionable in view of the large constituent quark masses induced by chiral symmetry breaking. We find that this can be explained by what we call nonchiral enhancement when finite quark masses are included in the holographic model, with good quantitative agreement with experimental data for $f_0(1710)$. Assuming the latter to indeed be a nearly pure glueball, the model makes essentially parameter-free and thus falsifiable predictions for its decay rates involving vector mesons and an upper limit on the $\\eta\\eta'$ decay rate.
Vector interaction strength in Polyakov-Nambu-Jona-Lasinio models from hadron-quark phase diagrams
Lourenço, O; Frederico, T; Delfino, A; Malheiro, M
2012-01-01
We estimate the vector interaction strength of the Polyakov-Nambu-Jona-Lasinio (PNJL) parametrizations, assuming that its transition curves should be as close as possible of the recently studied RMF-PNJL hadron-quark phase diagrams. Such diagrams are obtained matching relativistic mean-field hadronic models, and the PNJL quark ones. By using this method we found for the magnitude of the vector interaction, often treated as a free parameter, a range of 7.66 GeV$^{-2}\\lesssim G_V \\lesssim 16.13$ GeV$^{-2}$, or equivalently, $1.52 \\lesssim G_V/G_s \\lesssim 3.2$, with $G_s$ being the scalar coupling constant of the model. These values are compatible but restricts the range of 4 GeV$^{-2}\\lesssim G_V \\lesssim 19$ GeV$^{-2}$, recently obtained from lattice QCD data through a different mean-field model approach.
See-saw masses for quarks and leptons in an ambidextrous electroweak interaction model
Energy Technology Data Exchange (ETDEWEB)
Rajpoot, S.
1986-12-01
An ambidextrous electroweak interaction model with SU(2)/sub L/XSU(2)/sub R/XU(1) gauge symmetry is described in which the conventional quarks and leptons are accompanied by a set of new fermions that transform as singlets of SU(2)/sub L/XSU(2)/sub R/. The model has only two doublets of Higgs scalars. The masses of all known quarks and leptons result from the see-saw mechanism between the conventional fermions and the new ''singlet'' fermions. Neutrino neutral current interactions are identical to those of the standard SU(2)/sub L/XU(1) model. The singlet fermion masses lie in the 100-GeV to 1-TeV range to be probed by the oncoming accelerators of the 1990's.
See-saw masses for quarks and leptons in an ambidextrous electroweak interaction model
Energy Technology Data Exchange (ETDEWEB)
Rajpoot, S.
1987-06-04
An ambidextrous electroweak interaction model with SU(2)/sub L/xSU(2)/sub R/xU(1) gauge symmetry is described in which the conventional quarks and leptons are accompanied by a set of new fermions that transform as singlets of SU(2)/sub L/xSU(2)/sub R/. The model has only two doublets of Higgs scalars. The masses of all known quarks and leptons result from the see-saw mechanism between the conventional fermions and the new 'singlet' fermions. Neutrino neutral current interactions are identical to those of the standard SU(2)/sub L/xU(1) model. The singlet fermion masses lie in the 100 GeV to 1 TeV range, to be probed by the oncoming accelerators of the 1990's.
See-saw masses for quarks and leptons in an ambidextrous electroweak interaction model
Energy Technology Data Exchange (ETDEWEB)
Rajpoot, S.
1987-05-01
An ambidextrous electroweak interaction model with SU(2)/sub L/ x SU(2)/sub R/ x U(1) gauge symmetry is described in which the conventional quarks and leptons are accompanied by a set of new fermions that transform as singlets of SU(2)/sub L/ x SU(2)/sub R/. The model has only two doublets of Higgs scalars. The masses of all known quarks and leptons result from the see-saw mechanism between the conventional fermions and the new ''singlet'' fermions. Neutrino neutral current interactions are identical to those of the standard SU(2)/sub L/ x U(1) model. The singlet fermion masses lie in the 100-GeV to 1-TeV range to be probed by the oncoming accelerators of the 1990's.
See-saw masses for quarks and leptons in an ambidextrous electroweak interaction model
Rajpoot, S.
1987-06-01
An ambidextrous electroweak interaction model with SU(2) L× SU(2) R×U(1) gauge symmetry is described in which the conventional quarks and leptons are accompanied by a set of new fermions that transform as singlets of SU(2) L×SU(2) R. The model has only two doublets of Higgs scalars. The masses of all known quarks and leptons result from the see-saw mechanism between the conventional fermions and the new “singles” fermions. Neutrino neutral current interactions are identical to those of the standard SU(2) L×U(1) model. The singlet fermion masses lie in the 100 GeV to 1 TeV range, to be probed by the oncoming accelerators of the 1990's.
Quark-Model Baryon-Baryon Interaction and its Applications to Hypernuclei
Fujiwara, Y; Suzuki, Y; Kohno, M; Miyagawa, K
2004-01-01
The quark-model baryon-baryon interaction fss2, proposed by the Kyoto-Niigata group, is a unified model for the complete baryon octet (B_8=N, Lambda, Sigma and Xi), which is formulated in a framework of the (3q)-(3q) resonating-group method (RGM) using the spin-flavor SU_6 quark-model wave functions and effective meson-exchange potentials at the quark level. Model parameters are determined to reproduce properties of the nucleon-nucleon system and the low-energy cross section data for the hyperon-nucleon scattering. Due to the several improvements including the introduction of vector-meson exchange potentials, fss2 has achieved very accurate description of the NN and YN interactions, comparable to various one-boson exchange potentials. We review the essential features of fss2 and our previous model FSS, and their predictions to few-body systems in confrontation with the available experimental data. Some characteristic features of the B_8 B_8 interactions with the higher strangeness, S=-2, -3, -4, predicted by ...
Consistent parameter fixing in the quark-meson model with vacuum fluctuations
Carignano, Stefano; Buballa, Michael; Elkamhawy, Wael
2016-08-01
We revisit the renormalization prescription for the quark-meson model in an extended mean-field approximation, where vacuum quark fluctuations are included. At a given cutoff scale the model parameters are fixed by fitting vacuum quantities, typically including the sigma-meson mass mσ and the pion decay constant fπ. In most publications the latter is identified with the expectation value of the sigma field, while for mσ the curvature mass is taken. When quark loops are included, this prescription is however inconsistent, and the correct identification involves the renormalized pion decay constant and the sigma pole mass. In the present article we investigate the influence of the parameter-fixing scheme on the phase structure of the model at finite temperature and chemical potential. Despite large differences between the model parameters in the two schemes, we find that in homogeneous matter the effect on the phase diagram is relatively small. For inhomogeneous phases, on the other hand, the choice of the proper renormalization prescription is crucial. In particular, we show that if renormalization effects on the pion decay constant are not considered, the model does not even present a well-defined renormalized limit when the cutoff is sent to infinity.
Strong decays of excited 1D charmed(-strange) mesons in the covariant oscillator quark model
Maeda, Tomohito; Yoshida, Kento; Yamada, Kenji; Ishida, Shin; Oda, Masuho
2016-05-01
Recently observed charmed mesons, D1* (2760), D3* (2760) and charmed-strange mesons, Ds1 * (2860), Ds3 * (2860), by BaBar and LHCb collaborations are considered to be plausible candidates for c q ¯ 13 DJ (q = u, d, s) states. We calculate the strong decays with one pion (kaon) emission of these states including well-established 1S and 1P charmed(-strange) mesons within the framework of the covariant oscillator quark model. The results obtained are compared with the experimental data and the typical nonrelativistic quark-model calculations. Concerning the results for 1S and 1P states, we find that, thanks to the relativistic effects of decay form factors, our model parameters take reasonable values, though our relativistic approach and the nonrelativistic quark model give similar decay widths in agreement with experiment. While the results obtained for 13 DJ=1,3 states are roughly consistent with the present data, they should be checked by the future precise measurement.
Sivers and Boer-Mulders functions in Light-Cone Quark Models
Energy Technology Data Exchange (ETDEWEB)
Pasquini, Barbara; Yuan, Feng
2010-01-29
Results for the naive-time-reversal-odd quark distributions in a light-cone quark model are presented. The final-state interaction effects are generated via single-gluon exchange mechanism. The formalism of light-cone wave functions is used to derive general expressions in terms of overlap of wave-function amplitudes describing the different orbital angular momentum components of the nucleon. In particular, the model predictions show a dominant contribution from S- and P-wave interference in the Sivers function and a significant contribution also from the interference of P and D waves in the Boer-Mulders function. The favourable comparison with existing phenomenological parametrizations motivates further applications to describe azimuthal asymmetries in hadronic reactions.
Excited bottom and bottom-strange mesons in the quark model
Lü, Qi-Fang; Pan, Ting-Ting; Wang, Yan-Yan; Wang, En; Li, De-Min
2016-10-01
In order to understand the possible q q ¯ quark-model assignments of the BJ(5840 ) and BJ(5960 ) recently reported by the LHCb Collaboration, we evaluate mass spectra, strong decays, and radiative decays of bottom and bottom-strange mesons in a nonrelativistic quark model. Comparing these predictions with the relevant experimental results, we suggest that the BJ(5840 ) and BJ(5960 ) can be identified as the B (2 1S0) and B (1 3D3) , respectively, and the B (5970 ) reported by the CDF Collaboration can be interpreted as the B (2 3S1) or B (1 3D3) . Further precise measurements of the width, spin and decay modes of the B (5970 ) are needed to distinguish these two assignments. These predictions of bottom and bottom-strange mesons can provide useful information to further experimental investigations.
Hyperon Single-Particle Potentials Calculated from SU6 Quark-Model Baryon-Baryon Interactions
Kohno, M; Fujita, T; Nakamoto, C; Suzuki, Y
2000-01-01
Using the SU6 quark-model baryon-baryon interaction recently developed by the Kyoto-Niigata group, we calculate NN, Lambda N and Sigma N G-matrices in ordinary nuclear matter. This is the first attempt to discuss the Lambda and Sigma single-particle potentials in nuclear medium, based on the realistic quark-model potential. The Lambda potential has the depth of more than 40 MeV, which is more attractive than the value expected from the experimental data of Lambda-hypernuclei. The Sigma potential turns out to be repulsive, the origin of which is traced back to the strong Pauli repulsion in the Sigma N (I=3/2) ^3S_1 state.
Pion-to-photon transition distribution amplitudes in the non-local chiral quark model
Kotko, Piotr
2008-01-01
We apply the non-local chiral quark model to study vector and axial pion-to-photon transition amplitudes that are needed as a nonperturbative input to estimate the cross section of pion annihilation into the real and virtual photon. We use a simple form of the non-locality that allows to perform all calculations in the Minkowski space and guaranties polynomiality of the TDA's. We note only residual dependence on the precise form of the cut-off function, however vector TDA that is symmetric in skewedness parameter in the local quark model is no longer symmetric in the non-local case. We calculate also the transition form-factors and compare them with existing experimental parametrizations.
Pion electro-production in the Roper region in chiral quark models
Golli, B; Fiolhais, M
2009-01-01
We present a method to calculate pion electro-production amplitudes in a coupled-channel framework incorporating quasi-bound quark-model states. The method offers a clear prescription how to extract the resonant part of the amplitudes, even in the presence of different decay channels and a strong mixing of neighbouring resonances. The method is applied to the calculation of the M1- and the S1- amplitudes in the P11 partial wave in a simple chiral quark model. A good agreement with the observed M1- amplitude is found with a significant contribution from the pion cloud. The same effect is also prominent in the S1- amplitude but a rather uncertain data prevent us to draw a definitive conclusion.
Electromagnetic Properties of S11 States in a Light Cone Quark Model
Institute of Scientific and Technical Information of China (English)
HE Jun; DONG Yu-Bing
2006-01-01
Using relativistic spin-flavor wave functions of a Lorentz-covariant light cone quark model, we calculate the electromagnetic form factors of two S11 resonances, N(1535) and N(1650), and the helicity amplitudes A1/2 and S1/2 for electroexcitation of the S11 resonances from the nucleon. The electromagnetic form factors of these S11 resonances are found to be similar to those of the nucleon in shape, while the charge form factor of neutral N(1650) is nearly zero. The relative peak height of the S11 charge form factors is controlled by the mixing angle common to both resonance wave functions. As in most quark models, there is a systematic overestimate of A1/2p in both N(1535) and N(1650) cases at the photon point. A sizeable S1/2 for all cases is produced as suggested by experiments.
Charge radii of octet and decuplet baryons in chiral constituent quark model
Indian Academy of Sciences (India)
Neetika Sharma; Harleen Dahiya
2013-09-01
The charge radii of the spin-$\\dfrac{1}{2}^{+}$ octet and spin-$\\dfrac{3}{2}^{+}$ decuplet baryons have been calculated in the framework of chiral constituent quark model ( CQM) using a general parametrization method (GPM). Our results are not only comparable with the latest experimental studies but also agree with other phenomenological models. The effects of (3) symmetry breaking pertaining to the strangeness contribution and GPM parameters pertaining to the one-, two- and three-quark contributions have also been investigated in detail and are found to be the key parameters in understanding the non-zero values for the neutral octet $(n, \\sum^{0}, \\Xi, )$ and decuplet $(^{0}, \\sum^{*0}, \\Xi^{*0})$ baryons.
Excited bottom and bottom-strange mesons in the quark model
Lü, Qi-Fang; Wang, Yan-Yan; Wang, En; Li, De-Min
2016-01-01
In order to understand the possible $q\\bar{q}$ quark-model assignments of the $B_J(5840)$ and $B_J(5960)$ recently reported by the LHCb Collaboration, we evaluate mass spectra, strong decays, and radiative decays of bottom and bottom-strange mesons in a nonrelativistic quark model. Comparing these predictions with the relevant experimental results, we suggest that the $B_J(5840)$ and $B_J(5960)$ can be identified as $B(2^1S_0)$ and $B(1^3D_3)$, respectively, and the $B(5970)$ reported by the CDF Collaboration can be interpreted as $B(2^3S_1)$ or $B(1^3D_3)$. Further precise measurements of the width, spin and decay modes of the $B(5970)$ are needed to distinguish these two assignments. These predictions of bottom and bottom-strange mesons can provide useful information to further experimental investigations.
Gaitan, R; de Oca, J H Montes; Martinez, R
2015-01-01
In this work we study the anomalous top quark-gluon couplings Chromoelectric and Chromomagnetic Dipole Moments, CEDM and CMDM, in a general THDM with CP violation. We find that this model provides an important contribution from the $Y_{tt}$ Yukawa coupling that needs to be taken into account. The CMDM and CEDM obtained are $\\Delta\\tilde{k} < 10^{-2}$ and $\\Delta \\tilde{d} < 10^{-4}$.
Production of phi-mesons on nuclear targets in the Quark-Gluon String model
Arakelyan, G H; Shabelski, Yu M
2016-01-01
We consider the experimental data on phi-meson production on nuclear targets, and we find that they present unusually small shadow corrections for the inclusive density in the midrapidity region. We also give a quantitatively consistent description of both the initial energy dependence and the A-dependence of the produced phi-mesons, obtained in the frame of the Quark-Gluon String Model.
$\\pi^0\\to\\gamma^*\\gamma$ transition form factor within Light Front Quark Model
Lih, Chong-Chung
2012-01-01
We study the transition form factor of $\\pi^0\\to\\gamma^* \\gamma$ as a function of the momentum transfer $Q^2$ within the light-front quark model (LFQM). We compare our result with the experimental data by BaBar as well as other calculations based on the LFQM in the literature. We show that our predicted form factor fits well with the experimental data, particularly those at the large $Q^2$ region.
A quark model calculation of yy->pipi including final-state interactions
Blundell, H G; Hay, G; Swanso, E
2000-01-01
A quark model calculation of the processes yy->pi+pi- and yy->pipi is performed. At tree level, only charged pions couple to the initial state photons and neutral pions are not exceeded in the final state. However a small but significant cross section is observed. We demonstrate that this may be accounted for by a rotation in isospin space induced by final-state interactions.
Pion Cloud Effects on △-N Mass Splitting from Quark Models
Institute of Scientific and Technical Information of China (English)
DONG Yu-Bing; FENG Qing-Guo
2002-01-01
Pion cloud effects on △-N mass splitting are studied based on quark models. Pseudo-scalar pion-quarkcoupling is discussed in the relativistic and nonrelativistic frameworks. We separately calculate the pion cloud effects bythe one-pion exchange potential and by another method which is consistent with the baryon chiral perturbation theory.Remark able discrepancy in the mass splitting between the two methods is shown.
Electromagnetic form factors of the baryon octet in the perturbative chiral quark model
Cheedket, S; Gutsche, T; Faessler, A; Pumsa-ard, K; Yan, Y; Gutsche, Th.; Faessler, Amand
2002-01-01
We apply the perturbative chiral quark model at one loop to analyze the electromagnetic form factors of the baryon octet. The analytic expressions for baryon form factors, which are given in terms of fundamental parameters of low-energy pion-nucleon physics(weak pion decay constant, axial nucleon coupling, strong pion-nucleon form factor), and the numerical results for baryon magnetic moments, charge and magnetic radii are presented. Our results are in good agreement with experimental data.
Momentum Fractions carried by quarks and gluons in models of proton structure functions at small $x$
Choudhury, D K; Kalita, K
2016-01-01
The paper reports analysis of momentum fractions carried by quarks and gluons in models of Proton structure functions at small $x$. First, we analyze the model proposed by Lastovicka based on self-similarity sometime back. We then make a similar analysis for a second model based on the same notion which is also free from singularity in $x$ : $0
Le Yaouanc, A; Morénas, V; Oliver, L; Pène, O; Raynal, J C
2000-01-01
The detailed way in which duality between sum of exclusive states and the free quark model description operates in semileptonic total decay widths, is analysed. It is made very explicit by the use of the non relativistic harmonic oscillator quark model in the SV limit, and a simple interaction current with the lepton pair. In particular, the Voloshin sum rule is found to eliminate the mismatches of order $\\delta m/m_b^2$.
Using the Single Quark Transition Model to predict nucleon resonance amplitudes
Ramalho, G
2014-01-01
We present predictions for the $\\gamma^\\ast N \\to N^\\ast$ helicity amplitudes, where $N^\\ast$ is a member of the $[70,1^-]$ supermultiplet. We combine the results from the single quark transition model for the helicity amplitudes with the results of the covariant spectator quark model for the $\\gamma^\\ast N \\to N^\\ast(1535)$ and $\\gamma^\\ast N \\to N^\\ast(1520)$ transitions. The theoretical estimations from the covariant spectator quark model are used to calculate three independent functions $A,B$, and $C$ of $Q^2$, where $Q^2=-q^2$ and $q$ is the momentum transfer. With the knowledge of the functions $A,B$, and $C$ we estimate the helicity amplitudes for the transitions $\\gamma^\\ast N \\to N^\\ast(1650)$, $\\gamma^\\ast N \\to N^\\ast(1700)$, $\\gamma^\\ast N \\to \\Delta(1620)$, and $\\gamma^\\ast N \\to \\Delta(1700)$. The analysis is restricted to reactions with proton targets. The predictions for the transition amplitudes are valid for $Q^2 > 2$ GeV$^2$.
Inhomogeneous phases in the quark-meson model with vacuum fluctuations
Carignano, Stefano; Schaefer, Bernd-Jochen
2014-01-01
Inhomogeneous chiral-symmetry breaking phases at non-vanishing chemical potential and temperature are studied within a two-flavor quark-meson model in the chiral limit. The analysis is performed beyond the standard mean-field approximation by taking into account the Dirac-sea contributions of the quarks. Compared with the case where the Dirac sea is neglected, we find that the inhomogeneous phase shrinks, but in general does not disappear. It is shown within a Ginzburg-Landau analysis that the Lifshitz point of the inhomogeneous phase coincides with the tricritical point if the ratio between sigma-meson and constituent quark mass in vacuum is chosen to be $m_\\sigma/M = 2$, corresponding to the fixed mass ratio in the Nambu--Jona-Lasinio model. In the present model, however, this ratio can be varied, offering the possibility to separate the two points. This is confirmed by our numerical calculations, which demonstrate a strong sensitivity of the size of the inhomogeneous phase on $m_\\sigma$. Finally, we uncove...
Light-by-Light Hadronic Corrections to the Muon G-2 Problem Within the Nonlocal Chiral Quark Model
Dorokhov, A. E.; Radzhabov, A. E.; Zhevlakov, A. S.
2017-03-01
Results of calculation of the light-by-light contribution from the lightest neutral pseudoscalar and scalar mesons and the dynamical quark loop to the muon anomalous magnetic moment are discussed in the framework of the nonlocal SU(3) × SU(3) chiral quark model. The model is based on four-quark interaction of the Nambu-Jona-Lasinio type and Kobayashi-Maskawa-`t Hooft six-quark interaction. The full kinematic dependence of vertices with off-shell mesons and photons in intermediate states in the light-by-light scattering amplitude is taken into account. All calculations are elaborated in explicitly gauge-invariant manner. These results complete calculations of all hadronic light-by-light scattering contributions to aμ in the leading order in the 1/Nc expansion. The final result does not allow the discrepancy between the experiment and the Standard Model to be explained.
Structures of (ΩΩ)0+ and (([1])Ω)1+ in Extended Chiral SU(3) Quark Model
Institute of Scientific and Technical Information of China (English)
ZHANG Zong-Ye; YU You-Wen; DAI Lian-Rong
2003-01-01
The structures of (ΩΩ)0+ and (([1])Ω)1+ are studied in the extended chiral SU(3) quark model in whichvector meson exchanges are included. The effect from the vector meson fields is very similar to that from the one-gluonexchange (OGE) interaction. Both in the chiral SU(3) quark model and in the extended chiral SU(3) quark model,di-omega (ΩΩ)0+ is always deeply bound, with over one hundred MeV binding energy, and (([1])Ω)1+ 's binding energyis around 20 MeV. An analysis shows that the quark exchange effect plays a very important role for making di-omega(ΩΩ)0+ deeply bound.
Single Production of Top Quark via eγ-Collision in Left-Right Twin Higgs Model
Institute of Scientific and Technical Information of China (English)
LIU Yao-Bei; WANG Xue-Lei; CAO Jun; HAN Hong-Mei
2008-01-01
In the context of the left-right twin Higgs (LRTH) model, we fist study single production of the standard model (SM) top quark via e-γ collisions. We find that the corrections of the LRTH model to the cross section of the process e-γ→ vebt might be observed only for f ≤ 750 GeV and the heavy top quark mass scale M ≥ 500 GeV in future integrated luminosity of ￡=100 fb-1. We also consider single production of the heavy top quark T via e-γ collisions. Our numerical results show that the possible signals of the heavy top quark T might be observed via the decay channel T→φ+b→tbb in future LC experiment with ∫8=3 TeV and ￡=500fb-1.
Silva, Antonio; Kim, Hyun-Chul
2013-01-01
We investigate the flavor decomposition of the electromagnetic form factors of the nucleon, based on the chiral quark-soliton model with symmetry-conserving quantization. We consider the rotational 1/N_c and linear strange-quark mass (m_s) corrections. To extend the results to higher momentum transfer, we take into account the kinematical relativistic effects. We discuss the results of the flavor-decomposed electromagnetic form factors in comparison with the recent experimental data. In order to see the effects of the strange quark, we compare the SU(3) results with those of SU(2). We finally discuss the transverse charge densities for both unpolarized and polarized nucleons.
Bottom-quark forward-backward asymmetry in the standard model and beyond.
Grinstein, Benjamín; Murphy, Christopher W
2013-08-09
We computed the bottom-quark forward-backward asymmetry at the Tevatron in the standard model (SM) and for several new physics scenarios. Near the Z pole, the SM bottom asymmetry is dominated by tree level exchanges of electroweak gauge bosons. While above the Z pole, next-to-leading order QCD dominates the SM asymmetry as was the case with the top-quark forward-backward asymmetry. Light new physics, M(NP)≲150 GeV, can cause significant deviations from the SM prediction for the bottom asymmetry. The bottom asymmetry can be used to distinguish between competing new physics (NP) explanations of the top asymmetry based on how the NP interferes with s-channel gluon and Z exchange.
Calculation of the Isgur-Wise function from a light-front constituent quark model
Simula, S
1996-01-01
The space-like elastic form factor of heavy-light pseudoscalar mesons is investigated within a light-front constituent quark model in order to evaluate the Isgur-Wise form factor. The relativistic composition of the constituent quark spins is properly taken into account using the Melosh rotations, and various heavy-meson wave function are considered, including the eigenfunctions of an effective light-front mass operator reproducing meson mass spectra. It is shown that in a wide range of values of the recoil the Isgur-Wise form factor exhibits a moderate dependence upon the choice of the heavy-meson wave function and is mainly governed by the effects of the confinement scale.
"Anti-glitches" in the Quark-Nova model for AXPs
Ouyed, Rachid; Koning, Nico
2013-01-01
In the Quark-Nova model, AXPs are quark stars surrounded by a degenerate iron-rich Keplerian ring (a few stellar radii away). AXP bursts are caused by accretion of chunks from the inner edge of the ring following magnetic field penetration. For bright bursts, the inner disk is prone to radiation induced warping which can tilt it into counter-rotation (i.e. retrograde). For AXP 1E2259+586, the 2002 burst satisfies the condition for the formation of a retrograde inner ring. We hypothesize the 2002 burst reversed the inner ring setting the scene for the 2012 outburst and "anti-glitch" when the retrograde inner ring was suddenly accreted leading to the basic observed properties of the 2012 event.
Probing Quark-Gluon-Plasma properties with a Bayesian model-to-data comparison
Cai, Tianji; Bernhard, Jonah; Ke, Weiyao; Bass, Steffen; Duke QCD Group Team
2016-09-01
Experiments at RHIC and LHC study a special state of matter called the Quark Gluon Plasma (QGP), where quarks and gluons roam freely, by colliding relativistic heavy-ions. Given the transitory nature of the QGP, its properties can only be explored by comparing computational models of its formation and evolution to experimental data. The models fall, roughly speaking, under two categories-those solely using relativistic viscous hydrodynamics (pure hydro model) and those that in addition couple to a microscopic Boltzmann transport for the later evolution of the hadronic decay products (hybrid model). Each of these models has multiple parameters that encode the physical properties we want to probe and that need to be calibrated to experimental data, a task which is computationally expensive, but necessary for the knowledge extraction and determination of the models' quality. Our group has developed an analysis technique based on Bayesian Statistics to perform the model calibration and to extract probability distributions for each model parameter. Following the previous work that applies the technique to the hybrid model, we now perform a similar analysis on a pure-hydro model and display the posterior distributions for the same set of model parameters. We also develop a set of criteria to assess the quality of the two models with respect to their ability to describe current experimental data. Funded by Duke University Goldman Sachs Research Fellowship.
Models for Quarks and Elementary Particles. Part IV: How Much do We Know of This Universe?
Directory of Open Access Journals (Sweden)
Neumann U. K. W.
2008-07-01
Full Text Available Essential laws and principles of the natural sciences were discovered at the high aggre- gation levels of matter such as molecules, metal crystals, atoms and elementary parti- cles. These principles reappear in these models in modified form at the fundamental level of the quarks. However, the following is probably true: since the principles apply at the fundamental level of the quarks they also have a continuing effect at the higher aggregation levels. In the manner of the law of mass action, eight processes for weak interaction are formulated, which are also called Weak Processes here. Rules for quark exchange of the reacting elementary particles are named and the quasi-Euclidian or complex spaces introduced in Part I associated with the respective particles. The weak processes are the gateway to the “second” strand of this universe which we practically do not know. The particles with complex space, e.g. the neutrino, form this second strand. According to the physical model of gravitation from Part III the particles of both strands have >-fields and are thus subject to the superposition, which results in the attraction by gravity of the particles of both strands. The weak processes (7 and (8 offer a fair chance for the elimination of highly radioactive waste.
Parton Distributions in Nucleon on the Basis of a Relativistic Independent Quark Model
Barik, N
2001-01-01
At a low resolution scale with $Q^2={\\mu}^2$ corresponding to the nucleon bound state; deep inelastic unpolarized structure functions $F_1(x,{\\mu}^2)$ and $F_2(x,{\\mu}^2)$ are derived with correct support using the symmetric part of the hadronic tensor under some simplifying assumptions in the Bjorken limit. For doing this; the nucleon in its ground state has been represented by a suitably constructed momentum wave packet of its valence quarks in their appropriate SU(6) spin flavor configuration with the momentum probability amplitude taken phenomenologically in reference to the independent quark model of scalar-vector harmonic potential. The valence quark distribution functions $u_v(x,{\\mu}^2)$ and $d_v(x,{\\mu}^2)$, extracted from the structure function $F_1(x,{\\mu}^2)$ in a parton model interpretation, satisfy normalization constraints as well as the momentum sum-rule requirements at a bound state scale of ${\\mu}^2=0.1 GeV^2$. QCD evolution of these distribution functions taken as the inputs; yields at $Q_0...
Light adjoint quarks in the instanton-dyon liquid model. IV.
Liu, Yizhuang; Shuryak, Edward; Zahed, Ismail
2016-11-01
We discuss the instanton-dyon liquid model with Nf Majorana quark flavors in the adjoint representation of color S Uc(2 ) at finite temperature. We briefly recall the index theorem on S1×R3 for twisted adjoint fermions in a Bogomolny-Prasad-Sommerfeld (BPS) dyon background of arbitrary holonomy and use the Atiyah-Drinfeld-Hitchin-Manin (ADHM) construction to derive the adjoint antiperiodic zero modes. We use these results to derive the partition function of an interacting instanton-dyon ensemble with Nf light and antiperiodic adjoint quarks. We develop the model in details by mapping the theory on a three-dimensional quantum effective theory with adjoint quarks with manifest S U (Nf)×Z4 Nf symmetry. Using a mean-field analysis at weak coupling and strong screening, we show that center symmetry requires the spontaneous breaking of chiral symmetry, which is shown to only take place for Nf=1 . For a sufficiently dense liquid, we find that the ground state is center symmetric and breaks spontaneously flavor symmetry through S U (Nf)×Z4 Nf→O (Nf). As the liquid dilutes with increasing temperature, center symmetry and chiral symmetry are restored. We present numerical and analytical estimates for the transition temperatures.
Light Adjoint Quarks in the Instanton-Dyon Liquid Model IV
Liu, Yizhuang; Zahed, Ismail
2016-01-01
We discuss the instanton-dyon liquid model with $N_f$ Majorana quark flavors in the adjoint representation of color $SU_c(2)$ at finite temperature. We briefly recall the index theorem on $S^1\\times R^3$ for twisted adjoint fermions in a BPS dyon background of arbitrary holonomy, and use the ADHM construction to explicit the adjoint anti-periodic zero modes. We use these results to derive the partition function of an interacting instanton-dyon ensemble with $N_f$ light and anti-periodic adjoint quarks. We develop the model in details by mapping the theory on a 3-dimensional quantum effective theory with adjoint quarks with manifest $SU(N_f)\\times Z_{4N_f}$ symmetry. Using a mean-field analysis at weak coupling and strong screening, we show that center symmetry requires the spontaneous breaking of chiral symmetry, which is shown to only take place for $N_f=1$. For a sufficiently dense liquid, we find that the ground state is center symmetric and breaks spontaneously flavor symmetry through $SU(N_f)\\times Z_{4N...
Models for Quarks and Elementary Particles --- Part IV: How Much Do We Know of This Universe?
Directory of Open Access Journals (Sweden)
Ulrich K. W. Neumann
2008-07-01
Full Text Available Essential laws and principles of the natural sciences were discovered at the high aggregation levels of matter such as molecules, metal crystals, atoms and elementary particles. These principles reappear in these models in modified form at the fundamental level of the quarks. However, the following is probably true: since the principles apply at the fundamental level of the quarks they also have a continuing effect at the higher aggregation levels. In the manner of the law of mass action, eight processes for weak interaction are formulated, which are also called Weak Processes here. Rules for quark exchange of the reacting elementary particles are named and the quasi-Euclidian or complex spaces introduced in Part I associated with the respective particles. The weak processes are the gateway to the second strand of this universe which we practically do not know. The particles with complex space, e.g. the neutrino, form this second strand. According to the physical model of gravitation from Part III the particles of both strands have fields and are thus subject to the superposition, which results in the attraction by gravity of the particles of both strands. The weak processes (7 and (8 offer a fair chance for the elimination of highly radioactive waste.
Stable hybrid stars within a SU(3) Quark-Meson-Model
Zacchi, Andreas; Schaffner-Bielich, Jürgen
2015-01-01
The inner regions of the most massive compact stellar objects might be occupied by a phase of quarks. Since the observations of the massive pulsars PSR J1614-2230 and of PSR J0348+0432 with about two solar masses, the equations of state constructing relativistic stellar models have to be constrained respecting these new limits. We discuss stable hybrid stars, i.e. compact objects with an outer layer composed of nuclear matter and with a core consisting of quark matter (QM). For the outer nuclear layer we utilize a density dependent nuclear equation of state and we use a chiral SU(3) Quark-Meson model with a vacuum energy pressure to describe the objects core. The appearance of a disconnected mass-radius branch emerging from the hybrid star branch implies the existence of a third family of compact stars, so called twin stars. Twin stars did not emerge as the transition pressure has to be relatively small with a large jump in energy density, which could not be satisfied within our approach. This is, among other...
Color confinement multi quark resonance
Energy Technology Data Exchange (ETDEWEB)
Wang Fan [Department of Physics, Nanjing University, Joint Center for Particle Nuclear Physics and Cosmology, Nanjing University and Pupil Mountain Observatory, Nanjing, 210008 (China); Ping, J.L. [Department of Physics, Nanjing Normal University, Nanjing, 210097 (China); Pang, H.R. [Department of Physics, Southeast University, Nanjing, 210008 (China); Chen, L.Z. [Department of Physics, Nanjing University, Joint Center for Particle Nuclear Physics and Cosmology, Nanjing University and Pupil Mountain Observatory, Nanjing, 210008 (China)
2007-06-15
A new kind microscopic resonance, the color confinement multi quark resonance is proposed and studied. The quark delocalization color screening model is compared to one of the chiral quark model, the Salamanca model, and a new mechanism of the intermediate range NN interaction, the mutual distortion of interacting nucleons, is checked to be similar to the {sigma} meson exchange.
Phenomenology of Left-Right Models in the quark sector
Silva, Luiz Vale
2016-01-01
A natural avenue to extend the Standard Model (SM) is to embed it into a more symmetric framework. Here, I focus in Left-Right (LR) Models, which treat left- and right-handed chiralities on equal footing. Important information about the structure of LR Models comes from meson-mixing observables. Due to the impact of the new contributions to these processes, I consider the calculation of the short-distance QCD effects correcting the LR Model contributions to meson-mixing observables at the Next-to-Leading Order. I then revisit the phenomenology of a simple realization of LR Models, containing doublet scalars, and combine in a global fit electroweak precision observables, direct searches of the new gauge bosons and meson oscillation observables, a task performed within the CKMfitter statistical framework. Finally, I also cover a different issue, namely the modeling of theoretical uncertainties, a class of uncertainties specially important for flavour physics. Different frequentist schemes are compared, and thei...
Dynamical P-parity breaking in effective quark model
Andrianov, A A; Yudichev, V L
1995-01-01
Fermion models with selfinteraction including derivatives of fields are investigated in the strong coupling regime. The existence of three phases is established in the two channel model near tricritical point. The special phase of dynamical P-parity breaking is found.
Keegan, Ronan M; Bibby, Jaclyn; Thomas, Jens; Xu, Dong; Zhang, Yang; Mayans, Olga; Winn, Martyn D; Rigden, Daniel J
2015-02-01
AMPLE clusters and truncates ab initio protein structure predictions, producing search models for molecular replacement. Here, an interesting degree of complementarity is shown between targets solved using the different ab initio modelling programs QUARK and ROSETTA. Search models derived from either program collectively solve almost all of the all-helical targets in the test set. Initial solutions produced by Phaser after only 5 min perform surprisingly well, improving the prospects for in situ structure solution by AMPLE during synchrotron visits. Taken together, the results show the potential for AMPLE to run more quickly and successfully solve more targets than previously suspected.
Nuclear Matter with Quark-Meson Coupling; 1, Comparison of Nontopological Soliton Models
Barnea, N; Barnea, Nir; Walhout, Timothy S.
1999-01-01
A system of nontopological solitons interacting through scalar and vector meson exchange is used to model nuclear matter. The models studied are of the Friedberg-Lee type, which exhibit dynamical bag formation due to the coupling of quarks to a scalar composite gluon field. It is shown that the chiral chromodielectric model gives the best fit to the empirical data. The presence of the scalar meson guarantees saturation and an increase of the proton charge radius with nuclear density consistent with the EMC effect.
The polarized structure function of the nucleons with a non-extensive statistical quark model
Trevisan, Luis A.; Mirez, Carlos
2013-05-01
We studied an application of nonextensive thermodynamics to describe the polarized structure function of nucleon, in a model where the usual Fermi-Dirac and Bose-Einstein energy distribution, often used in the statistical models, were replaced by the equivalent functions of the q-statistical. The parameters of the model are given by an effective temperature T, the q parameter (from Tsallis statistics), and the chemical potentials given by the corresponding up (u) and down (d) quark normalization in the nucleon and by Δu and Δd of the polarized functions.
Generalized Ginzburg–Landau approach to inhomogeneous phases in nonlocal chiral quark models
Energy Technology Data Exchange (ETDEWEB)
Carlomagno, J.P. [IFLP, CONICET – Dpto. de Física, FCE, Universidad Nacional de La Plata, C.C. 67, 1900 La Plata (Argentina); CONICET, Rivadavia 1917, 1033 Buenos Aires (Argentina); Gómez Dumm, D., E-mail: dumm@fisica.unlp.edu.ar [IFLP, CONICET – Dpto. de Física, FCE, Universidad Nacional de La Plata, C.C. 67, 1900 La Plata (Argentina); CONICET, Rivadavia 1917, 1033 Buenos Aires (Argentina); Scoccola, N.N. [CONICET, Rivadavia 1917, 1033 Buenos Aires (Argentina); Physics Department, Comisión Nacional de Energía Atómica, Av. Libertador 8250, 1429 Buenos Aires (Argentina); Universidad Favaloro, Solís 453, 1078 Buenos Aires (Argentina)
2015-05-18
We analyze the presence of inhomogeneous phases in the QCD phase diagram within the framework of nonlocal chiral quark models. We concentrate in particular in the positions of the tricritical (TCP) and Lifshitz (LP) points, which are studied in a general context using a generalized Ginzburg–Landau approach. We find that for all the phenomenologically acceptable model parametrizations considered the TCP is located at a higher temperature and a lower chemical potential in comparison with the LP. Consequently, these models seem to favor a scenario in which the onset of the first order transition between homogeneous phases is not covered by an inhomogeneous, energetically favored phase.
Search for the Standard Model Higgs Boson Produced in Association with Top Quarks
Energy Technology Data Exchange (ETDEWEB)
Wilson, Jonathan Samuel [Ohio State U.
2011-01-01
We have performed a search for the Standard Model Higgs boson produced in association with top quarks in the lepton plus jets channel. We impose no constraints on the decay of the Higgs boson. We employ ensembles of neural networks to discriminate events containing a Higgs boson from the dominant tt¯background, and set upper bounds on the Higgs production cross section. At a Higgs boson mass mH = 120 GeV/c2 , we expect to exclude a cross section 12.7 times the Standard Model prediction, and we observe an exclusion 27.4 times the Standard Model prediction with 95 % confidence.
Roy, Sabyasachi
2016-01-01
We report some approximate analytic form of meson wave function constructed upon solving Schrodinger equation with linear plus Coulomb type Cornell potential. With this wave function, we study Isgur-Wise function and its derivatives for heavy-light mesons in the infinite heavy quark mass limit. We also explore the elastic form factors, charge radii and decay constants of pseudoscalar mesons in this QCD inspired quark model approach.
The B=2 system in the chiral quark-soliton model with broken scale invariance
Sarti, Valentina Mantovani; Vento, Vicente
2013-01-01
We study the interaction between two B=1 states in the Chiral-Dilaton Model with scale invariance where baryons are described as non-topological solitons arising from the interaction of chiral mesons and quarks. By using the hedgehog solution for the B=1 states we construct, via a product ansatz, three possible B=2 configurations to analyse the role of the relative orientation of the hedgehog quills in the dynamics. We investigate the behaviour of these solutions in the range of long and intermediate distances between the two solitons. Since the product ansatz breaks down as the two solitons get close, we explore the short range distances regime by building up a six quarks bag and by evaluating the interaction energy as a function of the inter-soliton separation. We calculate the interaction energy as a function of the inter-soliton distance for the B=2 system and we show that for small separations the six quarks bag, assuming a hedgehog structure, provides a stable bound state that at large separations conne...
Unlocking the Standard Model. IV. N=2 generations of quarks : spectrum and mixing
Machet, Bruno
2013-01-01
The Glashow-Salam-Weinberg model for 2 generations of quarks is extended to 8 composite Higgs multiplets, with no adjunction of extra fermions. It is the minimal number of Higgs doublets required to suitably account, simultaneously, for the spectrum of pseudoscalar mesons that can be built with 4 quarks and for the mass of the W gauge bosons. These masses being used as input, together with elementary low energy considerations for the pions, we calculate all other parameters, masses and couplings. We focus in this work on the spectrum of the 8 Higgs bosons (which all potentially contribute to the W and quark masses), and on the mixing (Cabibbo) angle, leaving the study of couplings to a subsequent work. The Higgs bosons fall into one triplet, two doublets and one singlet. In the triplet stand three states with masses \\sqrt{2} x that of heaviest pseudoscalar meson D_s, which, for 2 generations, pushes them up to 2.80 GeV. The 2 components of the first doublet have masses close to 1.25 GeV. The singlet has a mas...
Spinodal Instabilities of Baryon-Rich Quark-gluon Plasma in the PNJL Model
Li, Feng
2016-01-01
Using the Polyakov-Nambu-Jona-Lasinia (PNJL) model, we study the spinodal instability of a baryon-rich quark-gluon plasma in the linear response theory. We find that the spinodal unstable region in the temperature and density plane shrinks with increasing wave number of the unstable mode and is also reduced if the effect of Polyakov loop is not included. In the small wave number or long wavelength limit, the spinodal boundaries in both cases of with and without the Polyakov loop coincide with those determined from the isothermal spinodal instability in the thermodynamic approach. Also, the vector interactions among quarks is found to suppress unstable modes of all wave numbers. Moreover, the growth rate of unstable modes initially increases with the wave number but is reduced when the wave number becomes large. Including the collisional effect from quark scattering via the linearized Boltzmann equation, we further find that it decreases the growth rate of unstable modes of all wave numbers. Relevance of these...
Energy Technology Data Exchange (ETDEWEB)
Ahmadov, A.; Azuelos, G.; Bauer, U.; Belyaev, A.; Berger, E. L.; Sullivan, Z.; Tait, T. M. P.
2000-03-24
The top quark, when it was finally discovered at Fermilab in 1995 completed the three-generation structure of the Standard Model (SM) and opened up the new field of top quark physics. Viewed as just another SM quark, the top quark appears to be a rather uninteresting species. Produced predominantly, in hadron-hadron collisions, through strong interactions, it decays rapidly without forming hadrons, and almost exclusively through the single mode t {r_arrow} Wb. The relevant CKM coupling V{sub tb} is already determined by the (three-generation) unitarity of the CKM matrix. Rare decays and CP violation are unmeasurable small in the SM. Yet the top quark is distinguished by its large mass, about 35 times larger than the mass of the next heavy quark, and intriguingly close to the scale of electroweak (EW) symmetry breaking. This unique property raises a number of interesting questions. Is the top quark mass generated by the Higgs mechanism as the SM predicts and is its mass related to the top-Higgs-Yukawa coupling? Or does it play an even more fundamental role in the EW symmetry breaking mechanism? If there are new particles lighter than the top quark, does the top quark decay into them? Could non-SM physics first manifest itself in non-standard couplings of the top quark which show up as anomalies in top quark production and decays? Top quark physics tries to answer these questions. Several properties of the top quark have already been examined at the Tevatron. These include studies of the kinematical properties of top production, the measurements of the top mass, of the top production cross-section, the reconstruction of t{bar t}pairs in the fully hadronic final states, the study of {tau} decays of the top quark, the reconstruction of hadronic decays of the W boson from top decays, the search for flavor changing neutral current decays, the measurement of the W helicity in top decays, and bounds on t{bar t} spin correlations. Most of these measurements are limited by
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.
Two-loop Induced Majorana Neutrino Mass in a Radiatively Induced Quark and Lepton Mass Model
Nomura, Takaaki
2016-01-01
A two-loop induced radiative neutrino model is proposed as an extension of our previous work in which the first and second generation standard model fermion masses are generated at one-loop level in both quark and lepton sectors. Then we discuss current neutrino oscillation data, lepton flavor violations, muon anomalous magnetic moment, and a bosonic dark matter candidate, for both the normal and inverted neutrino mass hierarchy. Our numerical analysis shows that less hierarchical Yukawa coupling constants can fit the experimental data with TeV scale dark matter.
Weak Interaction Models with New Quarks and Right-handed Currents
Wilczek, F. A.; Zee, A.; Kingsley, R. L.; Treiman, S. B.
1975-06-01
We discuss various weak interaction issues for a general class of models within the SU(2) x U(1) gauge theory framework, with special emphasis on the effects of right-handed, charged currents and of quarks bearing new quantum numbers. In particular we consider the restrictions on model building which are imposed by the small KL - KS mass difference and by the .I = = rule; and we classify various possibilities for neutral current interactions and, in the case of heavy mesons with new quantum numbers, various possibilities for mixing effects analogous to KL - KS mixing.
NN S-Wave Elastic Cross Section and Possible Bound States in a Constituent Quark Model
Institute of Scientific and Technical Information of China (English)
PANG Hou-Rong; PING Jia-Lun; WANG Fan
2008-01-01
In the framework of a chiral constituent quark model, considering the contributions of π annihilation and one-gluon annihilation, the proton-antiproton s-wave elastic scattering cross section experimental data can be reproduced by adjusting properly one-gluon annihilation coupling constant. After fixing the model parameters, we perform a dynamical calculation for all possible s-wave nucleon-antinucleon states. The results show that there is no s-wave bound state as indicated by a strong enhancement at threshold of pp in J/ψ and B decay.
Generalized vector form factors of the pion in a chiral quark model
Broniowski, Wojciech
2008-01-01
Generalized vector form factors of the pion, related to the moments of the generalized parton distribution functions, are evaluated in the Nambu--Jona-Lasinio model with the Pauli-Villars regularization. The lowest moments (the electromagnetic and the gravitational form factors) are compared to recent lattice data, with fair agreement. Predictions for higher-order moments are also made. Relevant features of the generalized form factors in the chiral quark models are highlighted and the role of the QCD evolution for the higher-order GFFs is stressed.
Testing the Standard Model by precision measurement of the weak charges of quarks
Energy Technology Data Exchange (ETDEWEB)
Ross Young; Roger Carlini; Anthony Thomas; Julie Roche
2007-05-01
In a global analysis of the latest parity-violating electron scattering measurements on nuclear targets, we demonstrate a significant improvement in the experimental knowledge of the weak neutral-current lepton-quark interactions at low-energy. The precision of this new result, combined with earlier atomic parity-violation measurements, limits the magnitude of possible contributions from physics beyond the Standard Model - setting a model-independent, lower-bound on the scale of new physics at ~1 TeV.
Baryon Magnetic Moment and Beta Decay Ratio in Colored Quark Cluster Model
Institute of Scientific and Technical Information of China (English)
HU Zheng-Feng; WANG Qing-Wu; DENG Jian-Liao; LEE Xi-Guo; DU Chun-Guang; WANG Yu-Zhu
2008-01-01
Baryon magnetic moments of p, n, ∑+, ∑-, 0, - and the beta decay ratios (GA/GV) of n → p, ∑- → n and 0 →∑+are calculated in a colored quark cluster model. With SU(3) breaking, the model gives a good fit to the experimental values of those baryon magnetic moments and the beta decay ratios. Our results show that the orbital motion has a significant contribution to the spin and magnetic moments of those baryons and the strange component in nucleon is small.
Quark structure of chiral solitons
Diakonov, D
2004-01-01
There is a prejudice that the chiral soliton model of baryons is something orthogonal to the good old constituent quark models. In fact, it is the opposite: the spontaneous chiral symmetry breaking in strong interactions explains the appearance of massive constituent quarks of small size thus justifying the constituent quark models, in the first place. Chiral symmetry ensures that constituent quarks interact very strongly with the pseudoscalar fields. The ``chiral soliton'' is another word for the chiral field binding constituent quarks. We show how the old SU(6) quark wave functions follow from the ``soliton'', however, with computable relativistic corrections and additional quark-antiquark pairs. We also find the 5-quark wave function of the exotic baryon Theta+.
QCD Equation of State From a Chiral Hadronic Model Including Quark Degrees of Freedom
Rau, Philip; Schramm, Stefan; Stöcker, Horst
2013-01-01
This work presents an effective model for strongly interacting matter and the QCD equation of state (EoS). The model includes both hadron and quark degrees of freedom and takes into account the transition of chiral symmetry restoration as well as the deconfinement phase transition. At low temperatures $T$ and baryonic densities $\\rho_B$ a hadron resonance gas is described using a SU(3)-flavor sigma-omega model and a quark phase is introduced in analogy to PNJL models for higher $T$ and $\\rho_B$. In this way, the correct asymptotic degrees of freedom are used in a wide range of $T$ and $\\rho_B$. Here, results of this model concerning the chiral and deconfinement phase transitions and thermodynamic model properties are presented. Large hadron resonance multiplicities in the transition region emphasize the importance of heavy-mass resonance states in this region and their impact on the chiral transition behavior. The resulting phase diagram of QCD matter at small chemical potentials is in line with latest lattic...
The nonstrange dibaryon and hidden-color effect in a chiral quark model
Energy Technology Data Exchange (ETDEWEB)
Dai, L.R.; Zhang, Y.N.; Sun, Y.L.; Shao, S.J. [Liaoning Normal University, Department of Physics, Dalian (China)
2016-09-15
The exotic nonstrange ΔΔ dibaryon with I(J{sup P}) = 0(3{sup +}) has been confirmed by the experimental data reported by WASA-at-COSY Collaboration, and the result is consistent with our theoretical prediction in the chiral SU(3) quark model and extended chiral SU(3) quark model, showing that the effect from hidden-color channel (CC) is important. In the present work, we further investigate another exotic nonstrange ΔΔ dibaryon with I(J{sup P}) = 3(0{sup +}) in the chiral SU(3) quark model that describes the energies of baryon ground states and the nucleon-nucleon (NN) scattering data satisfactorily. We perform a dynamical coupled-channel study of the ΔΔ-CC system with I(J{sup P}) = 3(0{sup +}) within the framework of resonating group method (RGM). We find that the binding energy of I(J{sup P}) = 3(0{sup +}) state is about 22.3 MeV and a root-mean-square radius (RMS) of 1.03 fm in single-channel calculation. Then we extend the model to include the CC channel to further study the I(J{sup P}) = 3(0{sup +}) state and find that the binding energy is about 31.3 MeV and RMS is 0.97 fm in coupled-channel calculation. We can see that the CC channel coupling has a relatively large effect on this state. The color screening effect is further considered and we find that the bound state property will not change much. It is shown that the binding energy of this state is stably ranged around several tens of MeV; it means that its mass is always lower than the threshold of the ΔΔ channel and higher than the mass of NΔπ. (orig.)
The nonstrange dibaryon and hidden-color effect in a chiral quark model
Dai, L. R.; Zhang, Y. N.; Sun, Y. L.; Shao, S. J.
2016-09-01
The exotic nonstrange ΔΔ dibaryon with I(JP) = 0(3+) has been confirmed by the experimental data reported by WASA-at-COSY Collaboration, and the result is consistent with our theoretical prediction in the chiral SU(3) quark model and extended chiral SU(3) quark model, showing that the effect from hidden-color channel ( CC is important. In the present work, we further investigate another exotic nonstrange ΔΔ dibaryon with I(JP) = 3(0+) in the chiral SU(3) quark model that describes the energies of baryon ground states and the nucleon-nucleon (NN) scattering data satisfactorily. We perform a dynamical coupled-channel study of the ΔΔ - CC system with I(JP) = 3(0+) within the framework of resonating group method (RGM). We find that the binding energy of I(JP) = 3(0+) state is about 22.3 MeV and a root-mean-square radius (RMS) of 1.03 fm in single-channel calculation. Then we extend the model to include the CC channel to further study the I(JP) = 3(0+) state and find that the binding energy is about 31.3 MeV and RMS is 0.97 fm in coupled-channel calculation. We can see that the CC channel coupling has a relatively large effect on this state. The color screening effect is further considered and we find that the bound state property will not change much. It is shown that the binding energy of this state is stably ranged around several tens of MeV; it means that its mass is always lower than the threshold of the ΔΔ channel and higher than the mass of NΔπ.
Electromagnetic properties of nucleons and hyperons in a Lorentz covariant quark model
Faessler, A; Holstein, B R; Lyubovitskij, V E; Nicmorus, D; Pumsa-ard, K; Faessler, Amand; Gutsche, Thomas; Holstein, Barry R.; Lyubovitskij, Valery E.; Nicmorus, Diana; Pumsa-ard, Kem
2006-01-01
We calculate magnetic moments of nucleons and hyperons and N -> Delta + gamma transition characteristics using a manifestly Lorentz covariant chiral quark approach for the study of baryons as bound states of constituent quarks dressed by a cloud of pseudoscalar mesons.
RGM study of the NN interaction in an extended quark model
Fujiwara, Y.; Hecht, K. T.
1987-02-01
The extended quark model study of the NN interaction, in which the ( q overlineq) excitations inherent in the quark-gluon interaction are explicitly incorporated into the model space, is completed with the inclusion of the ( q overlineq) ( q overlineq) excitations generated by RPA-type terms of the color Breit interaction. The new coupling kernels connecting the dominant (3q)-(3q) components of the NN system to the (3 q)-(3 q)( q overlineq)( q overlineq) components lead to potentials with the characteristics of conventional σ and δ meson exchange potentials and furnish the additional medium-range attraction needed to bind the deuteron. The full model is subjected to a quantitative test through a solution of the RGM equations in a coupled channel formalism. With one improvement of the model, to yield an Nπ tensor force with OPEP strength and long-range characteristics, this model leads to a prediction of the low-energy NN scattering data and deuteron bound state characteristics which is in semiquantitative agreement with the experimental data and is free of parameter adjustments.
Matsuda, K; Matsuda, Koichi; Nishiura, Hiroyuki
2006-01-01
We reconsider an universal mass matrix model which has a seesaw-invariant structure with four-zero texture common to all quarks and leptons. The CKM quark and MNS lepton mixing matrices of the model are analyzed analytically.We show that the model can be consistent with all the experimental data of neutrino oscillation and quark mixings by tuning free parameters of the model. It is also shown that the model predicts a relatively large value for (1,3) element of the MNS lepton mixing matrix, |(U_{MNS})_{13}|^2 \\simeq 2.6 \\times 10^{-2}. Using the seesaw mechanism, we also discuss the conditions for the components of the Dirac and the right-handed Majorana neutrino mass matrices which lead to the neutrino mass matrix consistent with the experimental data.
Testing the standard model by precision measurement of the weak charges of quarks.
Young, R D; Carlini, R D; Thomas, A W; Roche, J
2007-09-21
In a global analysis of the latest parity-violating electron scattering measurements on nuclear targets, we demonstrate a significant improvement in the experimental knowledge of the weak neutral-current lepton-quark interactions at low energy. The precision of this new result, combined with earlier atomic parity-violation measurements, places tight constraints on the size of possible contributions from physics beyond the standard model. Consequently, this result improves the lower-bound on the scale of relevant new physics to approximately 1 TeV.
A quark model study of strong decays of $X\\left( 3915\\right) $
González, P
2016-01-01
Strong decays of $X\\left( 3915\\right) $ are analyzed from two quark model descriptions of $X\\left( 3915\\right) $, a conventional one in terms of the Cornell potential and an unconventional one from a Generalized Screened potential. We conclude that the experimental suppression of the OZI allowed decay $X\\left( 3915\\right) \\rightarrow D\\overline{D}$ might be explained in both cases as due to the momentum dependence of the decay amplitude. However, the experimental significance of the OZI forbidden decay $X\\left( 3915\\right) \\rightarrow\\omega J/\\psi$ could favor an unconventional description.
The electroproduction of the $\\Delta$(1232) in the chiral quark-soliton model
Silva, A; Watabe, T; Fiolhais, M; Göke, K
2000-01-01
We calculate the ratios E2/M1 and C2/M1 for the electroproduction of the magnetic dipole amplitude M1 is also presented. The theory used is the chiral quark-soliton model, which is based in the instanton vaccum of the QCD. The calculations are performed in flavor SU(2) and SU(3) taking rotational ($1/N_c$) corrections into account. The results for the ratios agree qualitatively with the available data, although the magnitude of both ratios seems to underestimate the latest experimental results.
Nucleon shape and electromagnetic form factors in the chiral constituent quark model
Dahiya, Harleen
2010-01-01
The electromagnetic form factors are the most fundamental quantities to describe the internal structure of the nucleon and the shape of a spatially extended particle is determined by its intrinsic quadrupole moment which can be related to the charge radii. We have calculated the electromagnetic form factors, nucleon charge radii and the intrinsic quadrupole moment of the nucleon in the framework of chiral constituent quark model. The results obtained are comparable to the latest experimental studies and also show improvement over some theoretical interpretations.
The shape of the $\\Delta$ baryon in a covariant spectator quark model
Ramalho, G; Stadler, A
2012-01-01
Using a covariant spectator quark model that describes the recent lattice QCD data for the $\\Delta$ electromagnetic form factors and all available experimental data on $\\gamma N \\to \\Delta$ transitions, we analyze the charge and magnetic dipole distributions of the $\\Delta$ baryon and discuss its shape. We conclude that the quadrupole moment of the $\\Delta$ is a good indicator of the deformation and that the $\\Delta^+$ charge distribution has an oblate shape. We also calculate transverse moments and find that they do not lead to unambiguous conclusions about the underlying shape.
Study of the linked dipole chain model in heavy quark production at the Tevatron
Energy Technology Data Exchange (ETDEWEB)
Lipatov, Artem V. [Physical Department, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)]. E-mail: lipatov@theory.sinp.msu.ru; Leif Loennblad [Dept. of Theoretical Physics, Lund (Sweden)]. E-mail: Leif.Lonnblad@thep.lu.se; Zotov, Nikolai P. [D.V. Skobeltsyn Institute of Nuclear Physics, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)]. E-mail: zotov@theory.sinp.msu.ru
2004-01-01
We present calculations of charm and beauty production at Tevatron within the framework of k{sub T} -factorization, using the unintegrated gluon distributions as obtained from the Linked Dipole Chain model. The analysis covers transverse momentum and rapidity distributions and the azimuthal correlations between b and b-bar quarks (or rather muons from their decay) which are powerful tests for the different unintegrated gluon distributions. We compare the theoretical results with recent experimental data taken by D{phi} and CDF collaborations at the Tevatron Run I and II. (author)
Baryogenesis of the Universe in cSMCS Model plus Iso-Doublet Vector Quark
Darvishi, Neda
2016-01-01
CP violation of the SM is insufficient to explain the baryon asymmetry in the universe and therefore an additional source of CP violation is needed. Here the extension of the SM by a neutral complex scalar singlet with a nonzero vacuum expectation value (cSMCS) plus a heavy vector quark pair is considered. This model offers the spontaneous CP violation and proper description in the baryogenesis, it leads strong enough first-order electro-weak phase transition to suppress the baryon-violating sphaleron process.
T-\\mu phase diagram of the chiral quark model from a large flavor number expansion
Jakovác, A; Szép, Z; Szépfalusy, P; Szep, Zs.
2004-01-01
The chiral phase boundary of strong matter is determined in the T-\\mu plane from the chiral quark model, applying a non-perturbatively renormalised treatment, involving chains of pion-bubbles and 1-loop fermion contributions. In the absence of explicit symmetry breaking the second order portion of the phase boundary and the location of the tricritical point (TCP) are determined analytically. Sensitivity of the results to the renormalisation scale is carefully investigated. The softening of the sigma-pole near the second order transitions is confirmed.
Constraining the MIT Bag Model of Quark Matter with Gravitational Wave Observations
Benhar, O; Gualtieri, L; Marassi, S; Benhar, Omar; Ferrari, Valeria; Gualtieri, Leonardo; Marassi, Stefania
2006-01-01
Most theoretical studies of strange stars are based on the MIT bag model of quark matter, whose main parameter, the bag constant B, is only loosely constrained by phenomenology. We discuss the possibility that detection of gravitational waves emitted by a compact star may provide information on both the nature of the source and the value of B. Our results show that the combined knowledge of the frequency of the emitted gravitational wave and of the mass or the radiation radius of the source allows one to discriminate between strange stars and neutron stars and set stringent bounds on the bag constants.
Ground state heavy baryon production in a relativistic quark-diquark model
Nobary, M A Gomshi
2007-01-01
We use current-current interaction to calculate the fragmentation functions to describe the production of spin-1/2, spin-1/2$'$ and spin-3/2 baryons with massive constituents in a relativistic quark-diquark model. Our results are in their analytic forms and are applicable for singly, doubly and triply heavy baryons. We discuss the production of $\\Omega_{bbc}$, $\\Omega_{bcc}$ and $\\Omega_{ccc}$ baryons in some detail. The results are satisfactorily compared with those obtained for triply heavy baryons calculated in a perturbative regime within reasonable values of the parameters involved.
Regularities in hadron systematics, Regge trajectories and a string quark model
Energy Technology Data Exchange (ETDEWEB)
Chekanov, S.V. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Levchenko, B.B. [Moscow State Univ. (Russian Federation). Skobeltsyn Inst. of Nuclear Physics
2006-08-15
An empirical principle for the construction of a linear relationship between the total angular momentum and squared-mass of baryons is proposed. In order to examine linearity of the trajectories, a rigorous least-squares regression analysis was performed. Unlike the standard Regge-Chew-Frautschi approach, the constructed trajectories do not have non-linear behaviour. A similar regularity may exist for lowest-mass mesons. The linear baryonic trajectories are well described by a semi-classical picture based on a spinning relativistic string with tension. The obtained numerical solution of this model was used to extract the (di)quark masses. (orig.)
Weak electric and magnetic form factors for semileptonic baryon decays in an independent-quark model
Energy Technology Data Exchange (ETDEWEB)
Barik, N.; Dash, B.K.; Das, M.
1985-10-01
Weak electric and magnetic form factors for semileptonic baryon decays are calculated in a relativistic quark model based on the Dirac equation with the independent-quark confining potential of the form (1+..gamma../sup 0/)V(r). The values obtained for (g/sub 2//g/sub 1/), for various decay modes in a model with V(r) = a'r/sup 2/, are roughly of the same order as those predicted in the MIT bag model. However in a similar model with V(r) = (a/sup nu+1/r/sup ..nu../+V/sub 0/), the (g/sub 2//g/sub 1/) values agree with the nonrelativistic results of Donoghue and Holstein. Incorporating phenomenologically the effect of nonzero g/sub 2/ in the ratio (g/sub 1//f/sub 1/), we have estimated the values for (f/sub 2//f/sub 1/) for various semileptonic transitions. It is observed that SU(3)-symmetry breaking does not generate significant departures in (f/sub 2//f/sub 1/) values from the corresponding Cabibbo values.
Top Quark Decay t→ cb(b) in Topcolor-Assisted Technicolor Models
Institute of Scientific and Technical Information of China (English)
LIU Guo-Li
2009-01-01
The topcolor-assisted technicolor (TC2) model predicts the existence of the top-pions and the CP-even top-Higgs with large flavor-changing couplings to the top quark, which at tree-level can mediate the top quark three-body decay t→cb(b). We study this decay, show the dependence of the decay rate on the relevant TC2 parameters and compare the results with the predictions in the minimal supersymmetric model.We find that the decay rate in the TC2 model is much larger than that in the minimal supersymmetric model if the new particles are not too heavy.However, in consideration of the CDF and the LEP experiment limits, the top-pion mass is greater than 340 GeV in a more realistic parameter space, so the decay width of the channel t→cb(b) intermediated by top-pions will be depressed greatly and difficult to be detected at the future eollider.Thus, to observe this channel at the future collider, considering the topohiggs contribution may be the possible way when the masses of the top-pions and the top-higgs are not degenerate.
Top Quark Properties Measurements in CMS
Yazgan, Efe
Recent top quark properties measurements made with the CMS detector at the LHC are presented. The measurements summarized include spin correlation of top quark pairs, asymmetries, top quark mass, and the underlying event in top quark pair events. The results are compared to the standard model predictions and new physics models.
Top quark properties measurements in CMS
Yazgan, E.; CMS Collaboration
2017-07-01
Recent top quark properties measurements made with the CMS detector at the LHC are presented. The measurements summarized include spin correlation of top quark pairs, asymmetries, top quark mass, and the underlying event in top quark pair events. The results are compared to the standard model predictions and new physics models.
Energy Technology Data Exchange (ETDEWEB)
Montiel, Ariadna, E-mail: amontiel@fis.cinvestav.mx [Departamento de Física, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 14-740, 07000 México DF (Mexico); Salzano, Vincenzo, E-mail: vincenzo.salzano@ehu.es [Departamento de Física Teórica e Historia de la Ciencia, Universidad del País Vasco (UPV/EHU), Apdo. 644, E-48080 Bilbao (Spain); Lazkoz, Ruth, E-mail: ruth.lazkoz@ehu.es [Departamento de Física Teórica e Historia de la Ciencia, Universidad del País Vasco (UPV/EHU), Apdo. 644, E-48080 Bilbao (Spain)
2014-06-02
In this work we investigate if a small fraction of quarks and gluons, which escaped hadronization and survived as a uniformly spread perfect fluid, can play the role of both dark matter and dark energy. This fluid, as developed in [1], is characterized by two main parameters: β, related to the amount of quarks and gluons which act as dark matter; and γ, acting as the cosmological constant. We explore the feasibility of this model at cosmological scales using data from type Ia Supernovae (SNeIa), Long Gamma-Ray Bursts (LGRB) and direct observational Hubble data. We find that: (i) in general, β cannot be constrained by SNeIa data nor by LGRB or H(z) data; (ii) γ can be constrained quite well by all three data sets, contributing with ≈78% to the energy–matter content; (iii) when a strong prior on (only) baryonic matter is assumed, the two parameters of the model are constrained successfully.
Evolution of Yukawa couplings and quark flavour mixings in 2UED models
Abdalgabar, Ammar; Deandrea, Aldo; Tarhini, Ahmad
2013-01-01
The evolution equations of the Yukawa couplings and quark mixings are derived for the one-loop renormalization group equations in the two Universal Extra Dimension Models (UED), that is six-dimensional models, compactified in different possible ways to yield standard four space-time dimension. Different possibilities for the matter fields are discussed, such as the case of bulk propagating or localised brane fields. We discuss in both cases the evolution of the Yukawa couplings, the Jarlskog parameter and the CKM matrix elements, and we find that, for both scenarios, as we run up to the unification scale, significant renormalization group corrections are present. We also discuss the results of different observables of the five-dimensional UED model in comparison with these six-dimensional models and the model dependence of the results.
Simplified Models for Higgs Physics: Singlet Scalar and Vector-like Quark Phenomenology
Dolan, Matthew J; Krämer, M; Rizzo, T G
2016-01-01
Simplified models provide a useful tool to conduct the search and exploration of physics beyond the Standard Model in a model-independent fashion. In this work we consider the complementarity of indirect searches for new physics in Higgs couplings and distributions with direct searches for new particles, using a simplified model which includes a new singlet scalar resonance and vector-like fermions that can mix with the SM top-quark. We fit this model to the combined ATLAS and CMS 125 GeV Higgs production and coupling measurements and other precision electroweak constraints, and explore in detail the effects of the new matter content upon Higgs production and kinematics. We highlight some novel features and decay modes of the top partner phenomenology, and discuss prospects for Run II.
Simplified models for Higgs physics: singlet scalar and vector-like quark phenomenology
Dolan, Matthew J.; Hewett, J. L.; Krämer, M.; Rizzo, T. G.
2016-07-01
Simplified models provide a useful tool to conduct the search and exploration of physics beyond the Standard Model in a model-independent fashion. In this work we consider the complementarity of indirect searches for new physics in Higgs couplings and distributions with direct searches for new particles, using a simplified model which includes a new singlet scalar resonance and vector-like fermions that can mix with the SM top-quark. We fit this model to the combined ATLAS and CMS 125 GeV Higgs production and coupling measurements and other precision electroweak constraints, and explore in detail the effects of the new matter content upon Higgs production and kinematics. We highlight some novel features and decay modes of the top partner phenomenology, and discuss prospects for Run II.
Blossier, Benoit
2014-01-01
The 2-years old observation at LHC of a new boson, with a mass of 126 GeV, is a great achievement. Its interpretation as a Brout-Englert-Higgs boson is very plausible and appealing to complete the zoology of fundamental particles in the Standard Model. The interplay between theorists and experimentalists that we have witnessed has come with a huge work to determine with enough precision the parameters of the Standard Model: couplings, masses, mixing angles. Among the various tools developed by physicists, lattice QCD is particularly suitable to know those parameters in the quark sector. In this report I discuss the lattice measurement of Standard Model fundamental parameters that are closely related to Higgs boson: its main production mode is the gluon-gluon fusion, whose the magnitude is governed by the strong coupling constant, while its most favored decay channel, $H \\to b \\bar{b}$, has a coupling proportional to the $b$ quark mass. I outline the improvements brought by the lattice community: simulations w...
Confronting effective models for deconfinement in dense quark matter with lattice data
Andersen, Jens O; Naylor, William
2015-01-01
Ab initio numerical simulations of the thermodynamics of dense quark matter remain a challenge. Apart from the infamous sign problem, lattice methods have to deal with finite volume and discretization effects as well as with the necessity to introduce sources for symmetry-breaking order parameters. We study these artifacts in the Polyakov-loop-extended Nambu-Jona-Lasinio model, and compare its predictions to existing lattice data for cold and dense two-color matter with two flavors of Wilson quarks. To achieve even qualitative agreement with lattice data \\emph{requires} the introduction of two novel elements in the model: (i) explicit chiral symmetry breaking in the effective contact four-fermion interaction, referred to as the chiral twist, and (ii) renormalization of the Polyakov loop. The feedback of the dense medium to the gauge sector is modeled by a chemical-potential-dependent scale in the Polyakov-loop potential. In contrast to previously used analytical ans\\"atze, we determine its dependence on the c...
Bicudo, P.; Cardoso, M.
2016-11-01
We address q q Q ¯Q ¯ exotic tetraquark bound states and resonances with a fully unitarized and microscopic quark model. We propose a triple string flip-flop potential, inspired by lattice QCD tetraquark static potentials and flux tubes, combining meson-meson and double Y potentials. Our model includes the color excited potential, but neglects the spin-tensor potentials, as well as all the other relativistic effects. To search for bound states and resonances, we first solve the two-body mesonic problem. Then we develop fully unitary techniques to address the four-body tetraquark problem. We fold the four-body Schrödinger equation with the mesonic wave functions, transforming it into a two-body meson-meson problem with nonlocal potentials. We find bound states for some quark masses, including the one reported in lattice QCD. Moreover, we also find resonances and calculate their masses and widths, by computing the T matrix and finding its pole positions in the complex energy plane, for some quantum numbers. However, a detailed analysis of the quantum numbers where binding exists shows a discrepancy with recent lattice QCD results for the l l b ¯ b ¯ tetraquark bound states. We conclude that the string flip-flop models need further improvement.
Quark-Antiquark and Diquark Condensates in Vacuum in a 2D Two-Flavor Gross-Neveu Model
Bang-Rong, Z
2007-01-01
The analysis based on the renormalized effective potential indicates that, similar to in the 4D two-flavor Nambu-Jona-Lasinio (NJL) model, in a 2D two-flavor Gross-Neveu model, the interplay between the quark-antiquark and the diquark condensates in vacuum also depends on $G_S/H_S$, the ratio of the coupling constants in scalar quark-antiquark and scalar diquark channel. Only the pure quark-antiquark condensates exist if $G_S/H_S>2/3$ which is just the ratio of the color numbers of the quarks participating in the diquark and quark-antiquark condensates. The two condensates will coexist if $0
Heavy-to-Light Form Factors in the Final Hadron Large Energy Limit Covariant Quark Model Approach
Charles, J; Oliver, L; Pène, O; Raynal, J C
1999-01-01
We prove the full covariance of the heavy-to-light weak current matrix elements based on the Bakamjian-Thomas construction of relativistic quark models, in the heavy mass limit for the parent hadron and the large energy limit for the daughter one. Moreover, this quark model representation of the heavy-to-light form factors fulfills the general relations that were recently argued to hold in the corresponding limit of QCD, namely that there are only three independent form factors describing the B -> pi (rho) matrix elements, as well as the factorized scaling law sqrt(M)z(E) of the form factors with respect to the heavy mass M and large energy E. These results constitute another good property of the quark models à la Bakamjian-Thomas, which were previously shown to exhibit covariance and Isgur-Wise scaling in the heavy-to-heavy case.
Energy Technology Data Exchange (ETDEWEB)
Keegan, Ronan M. [STFC Rutherford Appleton Laboratory, Didcot OX11 0FA (United Kingdom); Bibby, Jaclyn; Thomas, Jens [University of Liverpool, Liverpool L69 7ZB (United Kingdom); Xu, Dong [Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037 (United States); Zhang, Yang [University of Michigan, Ann Arbor, MI 48109 (United States); Mayans, Olga [University of Liverpool, Liverpool L69 7ZB (United Kingdom); Winn, Martyn D. [Science and Technology Facilities Council Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Rigden, Daniel J., E-mail: drigden@liv.ac.uk [University of Liverpool, Liverpool L69 7ZB (United Kingdom); STFC Rutherford Appleton Laboratory, Didcot OX11 0FA (United Kingdom)
2015-02-01
Two ab initio modelling programs solve complementary sets of targets, enhancing the success of AMPLE with small proteins. AMPLE clusters and truncates ab initio protein structure predictions, producing search models for molecular replacement. Here, an interesting degree of complementarity is shown between targets solved using the different ab initio modelling programs QUARK and ROSETTA. Search models derived from either program collectively solve almost all of the all-helical targets in the test set. Initial solutions produced by Phaser after only 5 min perform surprisingly well, improving the prospects for in situ structure solution by AMPLE during synchrotron visits. Taken together, the results show the potential for AMPLE to run more quickly and successfully solve more targets than previously suspected.
Supernova Equation of State with an extended SU(3) Quark-Meson Model
Beisitzer, Thomas; Schaffner-Bielich, Juergen
2014-01-01
The quark-meson model is investigated for the two- and three-flavor case extended by contributions of vector mesons under conditions encountered in core-collapse supernova matter. Typical temperature ranges, densities and electron fractions, as found in core-collapse supernova simulations, are studied by implementing charge neutrality and local beta-equilibrium with respect to weak interactions. Within this framework, we analyze the resulting phase diagram and equation of state (EoS) and investigate the impact of undetermined parameters of the model. The EoS turns out to be relatively independent on the entropy per baryon but there are significant changes when going from the two-flavor to the three-flavor case due to the nontrivial contribution from the strange quarks which stay massive even at high densities. While an increasing vector meson coupling constant leads to a substantial stiffening of the EoS, we find that the impact of changing the scalar meson mass is equally strong and results in a softening of...
Transverse momentum broadening of heavy quark and gluon energy loss in Sakai-Sugimoto model
Pang, Yi
2008-01-01
In this paper, we calculate the transverse momentum diffusion coefficient kappa_T of heavy quark and gluon penetration length in the deconfinement phase of Sakai-Sugimoto model, which is known as a holographic dual of large N_c QCD. We find that for the heavy quark moving through the thermal plasma with a constant velocity v<1, the transverse momentum diffusion coefficient kappa_T is proportional to lamda*gamma^{{1/3}}*T^4/T_d, and the gluon penetration length delta x is proportional to E^{{2/5}}, these results are different from those calculated in N=4 super-Yang-Mills theory, in which kappa_T is proportional to lambda*gamma^{{1/2}}*T^3 and delta x is proportional to E^{{1/3}}, respectively. In the high energy limit, the difference between the two pairs of results should be evident, so we expect that the future LHC experiments can tell us which model is more closely related to the realistic strongly coupled QCD at finite temperature.
Quark matter at high density based on an extended confined isospin-density-dependent mass model
Qauli, A. I.; Sulaksono, A.
2016-01-01
We investigate the effect of the inclusion of relativistic Coulomb terms in a confined-isospin-density-dependent-mass (CIDDM) model of strange quark matter (SQM). We found that if we include the Coulomb term in scalar density form, the SQM equation of state (EOS) at high densities is stiffer but if we include the Coulomb term in vector density form it is softer than that of the standard CIDDM model. We also investigate systematically the role of each term of the extended CIDDM model. Compared with what was reported by Chu and Chen [Astrophys. J. 780, 135 (2014)], we found the stiffness of SQM EOS is controlled by the interplay among the oscillator harmonic, isospin asymmetry and Coulomb contributions depending on the parameter's range of these terms. We have found that the absolute stable condition of SQM and the mass of 2 M⊙ pulsars can constrain the parameter of oscillator harmonic κ1≈0.53 in the case the Coulomb term is excluded. If the Coulomb term is included, for the models with their parameters are consistent with SQM absolute stability condition, the 2.0 M⊙ constraint more prefers the maximum mass prediction of the model with the scalar Coulomb term than that of the model with the vector Coulomb term. On the contrary, the high densities EOS predicted by the model with the vector Coulomb is more compatible with the recent perturbative quantum chromodynamics result [1] than that predicted by the model with the scalar Coulomb. Furthermore, we also observed the quark composition in a very high density region depends quite sensitively on the kind of Coulomb term used.
Khachatryan, Vardan; Tumasyan, Armen; Adam, Wolfgang; Bergauer, Thomas; Dragicevic, Marko; Erö, Janos; Friedl, Markus; Fruehwirth, Rudolf; Ghete, Vasile Mihai; Hartl, Christian; Hörmann, Natascha; Hrubec, Josef; Jeitler, Manfred; Kiesenhofer, Wolfgang; Knünz, Valentin; Krammer, Manfred; Krätschmer, Ilse; Liko, Dietrich; Mikulec, Ivan; Rabady, Dinyar; Rahbaran, Babak; Rohringer, Herbert; Schöfbeck, Robert; Strauss, Josef; Treberer-Treberspurg, Wolfgang; Waltenberger, Wolfgang; Wulz, Claudia-Elisabeth; Mossolov, Vladimir; Shumeiko, Nikolai; Suarez Gonzalez, Juan; Alderweireldt, Sara; Bansal, Sunil; Cornelis, Tom; De Wolf, Eddi A; Janssen, Xavier; Knutsson, Albert; Lauwers, Jasper; Luyckx, Sten; Ochesanu, Silvia; Rougny, Romain; Van De Klundert, Merijn; Van Haevermaet, Hans; Van Mechelen, Pierre; Van Remortel, Nick; Van Spilbeeck, Alex; Blekman, Freya; Blyweert, Stijn; D'Hondt, Jorgen; Daci, Nadir; Heracleous, Natalie; Keaveney, James; Lowette, Steven; Maes, Michael; Olbrechts, Annik; Python, Quentin; Strom, Derek; Tavernier, Stefaan; Van Doninck, Walter; Van Mulders, Petra; Van Onsem, Gerrit Patrick; Villella, Ilaria; Caillol, Cécile; Clerbaux, Barbara; De Lentdecker, Gilles; Dobur, Didar; Favart, Laurent; Gay, Arnaud; Grebenyuk, Anastasia; Léonard, Alexandre; Mohammadi, Abdollah; Perniè, Luca; Randle-conde, Aidan; Reis, Thomas; Seva, Tomislav; Thomas, Laurent; Vander Velde, Catherine; Vanlaer, Pascal; Wang, Jian; Zenoni, Florian; Adler, Volker; Beernaert, Kelly; Benucci, Leonardo; Cimmino, Anna; Costantini, Silvia; Crucy, Shannon; Fagot, Alexis; Garcia, Guillaume; Mccartin, Joseph; Ocampo Rios, Alberto Andres; Poyraz, Deniz; Ryckbosch, Dirk; Salva Diblen, Sinem; Sigamani, Michael; Strobbe, Nadja; Thyssen, Filip; Tytgat, Michael; Yazgan, Efe; Zaganidis, Nicolas; Basegmez, Suzan; Beluffi, Camille; Bruno, Giacomo; Castello, Roberto; Caudron, Adrien; Ceard, Ludivine; Da Silveira, Gustavo Gil; Delaere, Christophe; Du Pree, Tristan; Favart, Denis; Forthomme, Laurent; Giammanco, Andrea; Hollar, Jonathan; Jafari, Abideh; Jez, Pavel; Komm, Matthias; Lemaitre, Vincent; Nuttens, Claude; Pagano, Davide; Perrini, Lucia; Pin, Arnaud; Piotrzkowski, Krzysztof; Popov, Andrey; Quertenmont, Loic; Selvaggi, Michele; Vidal Marono, Miguel; Vizan Garcia, Jesus Manuel; Beliy, Nikita; Caebergs, Thierry; Daubie, Evelyne; Hammad, Gregory Habib; Aldá Júnior, Walter Luiz; Alves, Gilvan; Brito, Lucas; Correa Martins Junior, Marcos; Dos Reis Martins, Thiago; Molina, Jorge; Mora Herrera, Clemencia; Pol, Maria Elena; Rebello Teles, Patricia; Carvalho, Wagner; Chinellato, Jose; Custódio, Analu; Melo Da Costa, Eliza; De Jesus Damiao, Dilson; De Oliveira Martins, Carley; Fonseca De Souza, Sandro; Malbouisson, Helena; Matos Figueiredo, Diego; Mundim, Luiz; Nogima, Helio; Prado Da Silva, Wanda Lucia; Santaolalla, Javier; Santoro, Alberto; Sznajder, Andre; Tonelli Manganote, Edmilson José; Vilela Pereira, Antonio; Bernardes, Cesar Augusto; Dogra, Sunil; Tomei, Thiago; De Moraes Gregores, Eduardo; Mercadante, Pedro G; Novaes, Sergio F; Padula, Sandra; Aleksandrov, Aleksandar; Genchev, Vladimir; Hadjiiska, Roumyana; Iaydjiev, Plamen; Marinov, Andrey; Piperov, Stefan; Rodozov, Mircho; Stoykova, Stefka; Sultanov, Georgi; Vutova, Mariana; Dimitrov, Anton; Glushkov, Ivan; Litov, Leander; Pavlov, Borislav; Petkov, Peicho; Bian, Jian-Guo; Chen, Guo-Ming; Chen, He-Sheng; Chen, Mingshui; Cheng, Tongguang; Du, Ran; Jiang, Chun-Hua; Plestina, Roko; Romeo, Francesco; Tao, Junquan; Wang, Zheng; Asawatangtrakuldee, Chayanit; Ban, Yong; Liu, Shuai; Mao, Yajun; Qian, Si-Jin; Wang, Dayong; Xu, Zijun; Zhang, Fengwangdong; Zhang, Linlin; Zou, Wei; Avila, Carlos; Cabrera, Andrés; Chaparro Sierra, Luisa Fernanda; Florez, Carlos; Gomez, Juan Pablo; Gomez Moreno, Bernardo; Sanabria, Juan Carlos; Godinovic, Nikola; Lelas, Damir; Polic, Dunja; Puljak, Ivica; Antunovic, Zeljko; Kovac, Marko; Brigljevic, Vuko; Kadija, Kreso; Luetic, Jelena; Mekterovic, Darko; Sudic, Lucija; Attikis, Alexandros; Mavromanolakis, Georgios; Mousa, Jehad; Nicolaou, Charalambos; Ptochos, Fotios; Razis, Panos A; Rykaczewski, Hans; Bodlak, Martin; Finger, Miroslav; Finger Jr, Michael; Assran, Yasser; Ellithi Kamel, Ali; Mahmoud, Mohammed; Radi, Amr; Kadastik, Mario; Murumaa, Marion; Raidal, Martti; Tiko, Andres; Eerola, Paula; Voutilainen, Mikko; Härkönen, Jaakko; Karimäki, Veikko; Kinnunen, Ritva; Lampén, Tapio; Lassila-Perini, Kati; Lehti, Sami; Lindén, Tomas; Luukka, Panja-Riina; Mäenpää, Teppo; Peltola, Timo; Tuominen, Eija; Tuominiemi, Jorma; Tuovinen, Esa; Wendland, Lauri; Talvitie, Joonas; Tuuva, Tuure; Besancon, Marc; Couderc, Fabrice; Dejardin, Marc; Denegri, Daniel; Fabbro, Bernard; Faure, Jean-Louis; Favaro, Carlotta; Ferri, Federico; Ganjour, Serguei; Givernaud, Alain; Gras, Philippe; Hamel de Monchenault, Gautier; Jarry, Patrick; Locci, Elizabeth; Malcles, Julie; Rander, John; Rosowsky, André; Titov, Maksym; Baffioni, Stephanie; Beaudette, Florian; Busson, Philippe; Chapon, Emilien; Charlot, Claude; Dahms, Torsten; Dobrzynski, Ludwik; Filipovic, Nicolas; Florent, Alice; Granier de Cassagnac, Raphael; Mastrolorenzo, Luca; Miné, Philippe; Naranjo, Ivo Nicolas; Nguyen, Matthew; Ochando, Christophe; Ortona, Giacomo; Paganini, Pascal; Regnard, Simon; Salerno, Roberto; Sauvan, Jean-Baptiste; Sirois, Yves; Veelken, Christian; Yilmaz, Yetkin; Zabi, Alexandre; Agram, Jean-Laurent; Andrea, Jeremy; Aubin, Alexandre; Bloch, Daniel; Brom, Jean-Marie; Chabert, Eric Christian; Chanon, Nicolas; Collard, Caroline; Conte, Eric; Fontaine, Jean-Charles; Gelé, Denis; Goerlach, Ulrich; Goetzmann, Christophe; Le Bihan, Anne-Catherine; Skovpen, Kirill; Van Hove, Pierre; Gadrat, Sébastien; Beauceron, Stephanie; Beaupere, Nicolas; Bernet, Colin; Boudoul, Gaelle; Bouvier, Elvire; Brochet, Sébastien; Carrillo Montoya, Camilo Andres; Chasserat, Julien; Chierici, Roberto; Contardo, Didier; Courbon, Benoit; Depasse, Pierre; El Mamouni, Houmani; Fan, Jiawei; Fay, Jean; Gascon, Susan; Gouzevitch, Maxime; Ille, Bernard; Kurca, Tibor; Lethuillier, Morgan; Mirabito, Laurent; Pequegnot, Anne-Laure; Perries, Stephane; Ruiz Alvarez, José David; Sabes, David; Sgandurra, Louis; Sordini, Viola; Vander Donckt, Muriel; Verdier, Patrice; Viret, Sébastien; Xiao, Hong; Tsamalaidze, Zviad; Autermann, Christian; Beranek, Sarah; Bontenackels, Michael; Edelhoff, Matthias; Feld, Lutz; Heister, Arno; Klein, Katja; Lipinski, Martin; Ostapchuk, Andrey; Preuten, Marius; Raupach, Frank; Sammet, Jan; Schael, Stefan; Schulte, Jan-Frederik; Weber, Hendrik; Wittmer, Bruno; Zhukov, Valery; Ata, Metin; Brodski, Michael; Dietz-Laursonn, Erik; Duchardt, Deborah; Erdmann, Martin; Fischer, Robert; Güth, Andreas; Hebbeker, Thomas; Heidemann, Carsten; Hoepfner, Kerstin; Klingebiel, Dennis; Knutzen, Simon; Kreuzer, Peter; Merschmeyer, Markus; Meyer, Arnd; Millet, Philipp; Olschewski, Mark; Padeken, Klaas; Papacz, Paul; Reithler, Hans; Schmitz, Stefan Antonius; Sonnenschein, Lars; Teyssier, Daniel; Thüer, Sebastian; Cherepanov, Vladimir; Erdogan, Yusuf; Flügge, Günter; Geenen, Heiko; Geisler, Matthias; Haj Ahmad, Wael; Hoehle, Felix; Kargoll, Bastian; Kress, Thomas; Kuessel, Yvonne; Künsken, Andreas; Lingemann, Joschka; Nowack, Andreas; Nugent, Ian Michael; Pistone, Claudia; Pooth, Oliver; Stahl, Achim; Aldaya Martin, Maria; Asin, Ivan; Bartosik, Nazar; Behr, Joerg; Behrens, Ulf; Bell, Alan James; Bethani, Agni; Borras, Kerstin; Burgmeier, Armin; Cakir, Altan; Calligaris, Luigi; Campbell, Alan; Choudhury, Somnath; Costanza, Francesco; Diez Pardos, Carmen; Dolinska, Ganna; Dooling, Samantha; Dorland, Tyler; Eckerlin, Guenter; Eckstein, Doris; Eichhorn, Thomas; Flucke, Gero; Garay Garcia, Jasone; Geiser, Achim; Gizhko, Andrii; Gunnellini, Paolo; Hauk, Johannes; Hempel, Maria; Jung, Hannes; Kalogeropoulos, Alexis; Karacheban, Olena; Kasemann, Matthias; Katsas, Panagiotis; Kieseler, Jan; Kleinwort, Claus; Korol, Ievgen; Krücker, Dirk; Lange, Wolfgang; Leonard, Jessica; Lipka, Katerina; Lobanov, Artur; Lohmann, Wolfgang; Lutz, Benjamin; Mankel, Rainer; Marfin, Ihar; Melzer-Pellmann, Isabell-Alissandra; Meyer, Andreas Bernhard; Mittag, Gregor; Mnich, Joachim; Mussgiller, Andreas; Naumann-Emme, Sebastian; Nayak, Aruna; Ntomari, Eleni; Perrey, Hanno; Pitzl, Daniel; Placakyte, Ringaile; Raspereza, Alexei; Ribeiro Cipriano, Pedro M; Roland, Benoit; Ron, Elias; Sahin, Mehmet Özgür; Salfeld-Nebgen, Jakob; Saxena, Pooja; Schoerner-Sadenius, Thomas; Schröder, Matthias; Seitz, Claudia; Spannagel, Simon; Vargas Trevino, Andrea Del Rocio; Walsh, Roberval; Wissing, Christoph; Blobel, Volker; Centis Vignali, Matteo; Draeger, Arne-Rasmus; Erfle, Joachim; Garutti, Erika; Goebel, Kristin; Görner, Martin; Haller, Johannes; Hoffmann, Malte; Höing, Rebekka Sophie; Junkes, Alexandra; Kirschenmann, Henning; Klanner, Robert; Kogler, Roman; Lapsien, Tobias; Lenz, Teresa; Marchesini, Ivan; Marconi, Daniele; Nowatschin, Dominik; Ott, Jochen; Peiffer, Thomas; Perieanu, Adrian; Pietsch, Niklas; Poehlsen, Jennifer; Pöhlsen, Thomas; Rathjens, Denis; Sander, Christian; Schettler, Hannes; Schleper, Peter; Schlieckau, Eike; Schmidt, Alexander; Seidel, Markus; Sola, Valentina; Stadie, Hartmut; Steinbrück, Georg; Troendle, Daniel; Usai, Emanuele; Vanelderen, Lukas; Vanhoefer, Annika; Akbiyik, Melike; Barth, Christian; Baus, Colin; Berger, Joram; Böser, Christian; Butz, Erik; Chwalek, Thorsten; De Boer, Wim; Descroix, Alexis; Dierlamm, Alexander; Feindt, Michael; Frensch, Felix; Giffels, Manuel; Gilbert, Andrew; Hartmann, Frank; Hauth, Thomas; Husemann, Ulrich; Katkov, Igor; Kornmayer, Andreas; Lobelle Pardo, Patricia; Mozer, Matthias Ulrich; Müller, Thomas; Müller, Thomas; Nürnberg, Andreas; Quast, Gunter; Rabbertz, Klaus; Röcker, Steffen; Simonis, Hans-Jürgen; Stober, Fred-Markus Helmut; Ulrich, Ralf; Wagner-Kuhr, Jeannine; Wayand, Stefan; Weiler, Thomas; Wöhrmann, Clemens; Wolf, Roger; Anagnostou, Georgios; Daskalakis, Georgios; Geralis, Theodoros; Giakoumopoulou, Viktoria Athina; Kyriakis, Aristotelis; Loukas, Demetrios; Markou, Athanasios; Markou, Christos; Psallidas, Andreas; Topsis-Giotis, Iasonas; Agapitos, Antonis; Kesisoglou, Stilianos; Panagiotou, Apostolos; Saoulidou, Niki; Stiliaris, Efstathios; Tziaferi, Eirini; Aslanoglou, Xenofon; Evangelou, Ioannis; Flouris, Giannis; Foudas, Costas; Kokkas, Panagiotis; Manthos, Nikolaos; Papadopoulos, Ioannis; Paradas, Evangelos; Strologas, John; Bencze, Gyorgy; Hajdu, Csaba; Hidas, Pàl; Horvath, Dezso; Sikler, Ferenc; Veszpremi, Viktor; Vesztergombi, Gyorgy; Zsigmond, Anna Julia; Beni, Noemi; Czellar, Sandor; Karancsi, János; Molnar, Jozsef; Palinkas, Jozsef; Szillasi, Zoltan; Makovec, Alajos; Raics, Peter; Trocsanyi, Zoltan Laszlo; Ujvari, Balazs; Swain, Sanjay Kumar; Beri, Suman Bala; Bhatnagar, Vipin; Gupta, Ruchi; Bhawandeep, Bhawandeep; Kalsi, Amandeep Kaur; Kaur, Manjit; Kumar, Ramandeep; Mittal, Monika; Nishu, Nishu; Singh, Jasbir; Kumar, Ashok; Kumar, Arun; Ahuja, Sudha; Bhardwaj, Ashutosh; Choudhary, Brajesh C; Kumar, Ajay; Malhotra, Shivali; Naimuddin, Md; Ranjan, Kirti; Sharma, Varun; Banerjee, Sunanda; Bhattacharya, Satyaki; Chatterjee, Kalyanmoy; Dutta, Suchandra; Gomber, Bhawna; Jain, Sandhya; Jain, Shilpi; Khurana, Raman; Modak, Atanu; Mukherjee, Swagata; Roy, Debarati; Sarkar, Subir; Sharan, Manoj; Abdulsalam, Abdulla; Dutta, Dipanwita; Kumar, Vineet; Mohanty, Ajit Kumar; Pant, Lalit Mohan; Shukla, Prashant; Topkar, Anita; Aziz, Tariq; Banerjee, Sudeshna; Bhowmik, Sandeep; Chatterjee, Rajdeep Mohan; Dewanjee, Ram Krishna; Dugad, Shashikant; Ganguly, Sanmay; Ghosh, Saranya; Guchait, Monoranjan; Gurtu, Atul; Kole, Gouranga; Kumar, Sanjeev; Maity, Manas; Majumder, Gobinda; Mazumdar, Kajari; Mohanty, Gagan Bihari; Parida, Bibhuti; Sudhakar, Katta; Wickramage, Nadeesha; Sharma, Seema; Bakhshiansohi, Hamed; Behnamian, Hadi; Etesami, Seyed Mohsen; Fahim, Ali; Goldouzian, Reza; Khakzad, Mohsen; Mohammadi Najafabadi, Mojtaba; Naseri, Mohsen; Paktinat Mehdiabadi, Saeid; Rezaei Hosseinabadi, Ferdos; Safarzadeh, Batool; Zeinali, Maryam; Felcini, Marta; Grunewald, Martin; Abbrescia, Marcello; Calabria, Cesare; Chhibra, Simranjit Singh; Colaleo, Anna; Creanza, Donato; Cristella, Leonardo; De Filippis, Nicola; De Palma, Mauro; Fiore, Luigi; Iaselli, Giuseppe; Maggi, Giorgio; Maggi, Marcello; My, Salvatore; Nuzzo, Salvatore; Pompili, Alexis; Pugliese, Gabriella; Radogna, Raffaella; Selvaggi, Giovanna; Sharma, Archana; Silvestris, Lucia; Venditti, Rosamaria; Verwilligen, Piet; Abbiendi, Giovanni; Benvenuti, Alberto; Bonacorsi, Daniele; Braibant-Giacomelli, Sylvie; Brigliadori, Luca; Campanini, Renato; Capiluppi, Paolo; Castro, Andrea; Cavallo, Francesca Romana; Codispoti, Giuseppe; Cuffiani, Marco; Dallavalle, Gaetano-Marco; Fabbri, Fabrizio; Fanfani, Alessandra; Fasanella, Daniele; Giacomelli, Paolo; Grandi, Claudio; Guiducci, Luigi; Marcellini, Stefano; Masetti, Gianni; Montanari, Alessandro; Navarria, Francesco; Perrotta, Andrea; Rossi, Antonio; Rovelli, Tiziano; Siroli, Gian Piero; Tosi, Nicolò; Travaglini, Riccardo; Albergo, Sebastiano; Cappello, Gigi; Chiorboli, Massimiliano; Costa, Salvatore; Giordano, Ferdinando; Potenza, Renato; Tricomi, Alessia; Tuve, Cristina; Barbagli, Giuseppe; Ciulli, Vitaliano; Civinini, Carlo; D'Alessandro, Raffaello; Focardi, Ettore; Gallo, Elisabetta; Gonzi, Sandro; Gori, Valentina; Lenzi, Piergiulio; Meschini, Marco; Paoletti, Simone; Sguazzoni, Giacomo; Tropiano, Antonio; Benussi, Luigi; Bianco, Stefano; Fabbri, Franco; Piccolo, Davide; Ferretti, Roberta; Ferro, Fabrizio; Lo Vetere, Maurizio; Robutti, Enrico; Tosi, Silvano; Dinardo, Mauro Emanuele; Fiorendi, Sara; Gennai, Simone; Gerosa, Raffaele; Ghezzi, Alessio; Govoni, Pietro; Lucchini, Marco Toliman; Malvezzi, Sandra; Manzoni, Riccardo Andrea; Martelli, Arabella; Marzocchi, Badder; Menasce, Dario; Moroni, Luigi; Paganoni, Marco; Pedrini, Daniele; Ragazzi, Stefano; Redaelli, Nicola; Tabarelli de Fatis, Tommaso; Buontempo, Salvatore; Cavallo, Nicola; Di Guida, Salvatore; Fabozzi, Francesco; Iorio, Alberto Orso Maria; Lista, Luca; Meola, Sabino; Merola, Mario; Paolucci, Pierluigi; Azzi, Patrizia; Bacchetta, Nicola; Bisello, Dario; Carlin, Roberto; Checchia, Paolo; Dall'Osso, Martino; Dorigo, Tommaso; Dosselli, Umberto; Fanzago, Federica; Gasparini, Fabrizio; Gasparini, Ugo; Gonella, Franco; Gozzelino, Andrea; Lacaprara, Stefano; Margoni, Martino; Meneguzzo, Anna Teresa; Pazzini, Jacopo; Pozzobon, Nicola; Ronchese, Paolo; Simonetto, Franco; Torassa, Ezio; Tosi, Mia; Zotto, Pierluigi; Zucchetta, Alberto; Zumerle, Gianni; Gabusi, Michele; Ratti, Sergio P; Re, Valerio; Riccardi, Cristina; Salvini, Paola; Vitulo, Paolo; Biasini, Maurizio; Bilei, Gian Mario; Ciangottini, Diego; Fanò, Livio; Lariccia, Paolo; Mantovani, Giancarlo; Menichelli, Mauro; Saha, Anirban; Santocchia, Attilio; Spiezia, Aniello; Androsov, Konstantin; Azzurri, Paolo; Bagliesi, Giuseppe; Bernardini, Jacopo; Boccali, Tommaso; Broccolo, Giuseppe; Castaldi, Rino; Ciocci, Maria Agnese; Dell'Orso, Roberto; Donato, Silvio; Fedi, Giacomo; Fiori, Francesco; Foà, Lorenzo; Giassi, Alessandro; Grippo, Maria Teresa; Ligabue, Franco; Lomtadze, Teimuraz; Martini, Luca; Messineo, Alberto; Moon, Chang-Seong; Palla, Fabrizio; Rizzi, Andrea; Savoy-Navarro, Aurore; Serban, Alin Titus; Spagnolo, Paolo; Squillacioti, Paola; Tenchini, Roberto; Tonelli, Guido; Venturi, Andrea; Verdini, Piero Giorgio; Vernieri, Caterina; Barone, Luciano; Cavallari, Francesca; D'imperio, Giulia; Del Re, Daniele; Diemoz, Marcella; Jorda, Clara; Longo, Egidio; Margaroli, Fabrizio; Meridiani, Paolo; Micheli, Francesco; Organtini, Giovanni; Paramatti, Riccardo; Rahatlou, Shahram; Rovelli, Chiara; Santanastasio, Francesco; Soffi, Livia; Traczyk, Piotr; Amapane, Nicola; Arcidiacono, Roberta; Argiro, Stefano; Arneodo, Michele; Bellan, Riccardo; Biino, Cristina; Cartiglia, Nicolo; Casasso, Stefano; Costa, Marco; Covarelli, Roberto; Degano, Alessandro; Demaria, Natale; Finco, Linda; Mariotti, Chiara; Maselli, Silvia; Migliore, Ernesto; Monaco, Vincenzo; Musich, Marco; Obertino, Maria Margherita; Pacher, Luca; Pastrone, Nadia; Pelliccioni, Mario; Pinna Angioni, Gian Luca; Potenza, Alberto; Romero, Alessandra; Ruspa, Marta; Sacchi, Roberto; Solano, Ada; Staiano, Amedeo; Tamponi, Umberto; Belforte, Stefano; Candelise, Vieri; Casarsa, Massimo; Cossutti, Fabio; Della Ricca, Giuseppe; Gobbo, Benigno; La Licata, Chiara; Marone, Matteo; Schizzi, Andrea; Umer, Tomo; Zanetti, Anna; Chang, Sunghyun; Kropivnitskaya, Anna; Nam, Soon-Kwon; Kim, Dong Hee; Kim, Gui Nyun; Kim, Min Suk; Kong, Dae Jung; Lee, Sangeun; Oh, Young Do; Park, Hyangkyu; Sakharov, Alexandre; Son, Dong-Chul; Kim, Tae Jeong; Ryu, Min Sang; Kim, Jae Yool; Moon, Dong Ho; Song, Sanghyeon; Choi, Suyong; Gyun, Dooyeon; Hong, Byung-Sik; Jo, Mihee; Kim, Hyunchul; Kim, Yongsun; Lee, Byounghoon; Lee, Kyong Sei; Park, Sung Keun; Roh, Youn; Yoo, Hwi Dong; Choi, Minkyoo; Kim, Ji Hyun; Park, Inkyu; Ryu, Geonmo; Choi, Young-Il; Choi, Young Kyu; Goh, Junghwan; Kim, Donghyun; Kwon, Eunhyang; Lee, Jongseok; Yu, Intae; Juodagalvis, Andrius; Komaragiri, Jyothsna Rani; Md Ali, Mohd Adli Bin; Wan Abdullah, Wan Ahmad Tajuddin; Casimiro Linares, Edgar; Castilla-Valdez, Heriberto; De La Cruz-Burelo, Eduard; Heredia-de La Cruz, Ivan; Hernandez-Almada, Alberto; Lopez-Fernandez, Ricardo; Sánchez Hernández, Alberto; Carrillo Moreno, Salvador; Vazquez Valencia, Fabiola; Pedraza, Isabel; Salazar Ibarguen, Humberto Antonio; Morelos Pineda, Antonio; Krofcheck, David; Butler, Philip H; Reucroft, Steve; Ahmad, Ashfaq; Ahmad, Muhammad; Hassan, Qamar; Hoorani, Hafeez R; Khan, Wajid Ali; Khurshid, Taimoor; Shoaib, Muhammad; Bialkowska, Helena; Bluj, Michal; Boimska, Bożena; Frueboes, Tomasz; Górski, Maciej; Kazana, Malgorzata; Nawrocki, Krzysztof; Romanowska-Rybinska, Katarzyna; Szleper, Michal; Zalewski, Piotr; Brona, Grzegorz; Bunkowski, Karol; Cwiok, Mikolaj; Dominik, Wojciech; Doroba, Krzysztof; Kalinowski, Artur; Konecki, Marcin; Krolikowski, Jan; Misiura, Maciej; Olszewski, Michał; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Di Francesco, Agostino; Faccioli, Pietro; Ferreira Parracho, Pedro Guilherme; Gallinaro, Michele; Lloret Iglesias, Lara; Nguyen, Federico; Rodrigues Antunes, Joao; Seixas, Joao; Toldaiev, Oleksii; Vadruccio, Daniele; Varela, Joao; Vischia, Pietro; Bunin, Pavel; Gavrilenko, Mikhail; Golutvin, Igor; Kamenev, Alexey; Karjavin, Vladimir; Konoplyanikov, Viktor; Kozlov, Guennady; Lanev, Alexander; Malakhov, Alexander; Matveev, Viktor; Moisenz, Petr; Palichik, Vladimir; Perelygin, Victor; Savina, Maria; Shmatov, Sergey; Shulha, Siarhei; Smirnov, Vitaly; Zarubin, Anatoli; Golovtsov, Victor; Ivanov, Yury; Kim, Victor; Kuznetsova, Ekaterina; Levchenko, Petr; Murzin, Victor; Oreshkin, Vadim; Smirnov, Igor; Sulimov, Valentin; Uvarov, Lev; Vavilov, Sergey; Vorobyev, Alexey; Vorobyev, Andrey; Andreev, Yuri; Dermenev, Alexander; Gninenko, Sergei; Golubev, Nikolai; Kirsanov, Mikhail; Krasnikov, Nikolai; Pashenkov, Anatoli; Tlisov, Danila; Toropin, Alexander; Epshteyn, Vladimir; Gavrilov, Vladimir; Lychkovskaya, Natalia; Popov, Vladimir; Pozdnyakov, Ivan; Safronov, Grigory; Semenov, Sergey; Spiridonov, Alexander; Stolin, Viatcheslav; Vlasov, Evgueni; Zhokin, Alexander; Andreev, Vladimir; Azarkin, Maksim; Dremin, Igor; Kirakosyan, Martin; Leonidov, Andrey; Mesyats, Gennady; Rusakov, Sergey V; Vinogradov, Alexey; Belyaev, Andrey; Boos, Edouard; Bunichev, Viacheslav; Dubinin, Mikhail; Dudko, Lev; Ershov, Alexander; Gribushin, Andrey; Klyukhin, Vyacheslav; Kodolova, Olga; Lokhtin, Igor; Obraztsov, Stepan; Petrushanko, Sergey; Savrin, Viktor; Azhgirey, Igor; Bayshev, Igor; Bitioukov, Sergei; Kachanov, Vassili; Kalinin, Alexey; Konstantinov, Dmitri; Krychkine, Victor; Petrov, Vladimir; Ryutin, Roman; Sobol, Andrei; Tourtchanovitch, Leonid; Troshin, Sergey; Tyurin, Nikolay; Uzunian, Andrey; Volkov, Alexey; Adzic, Petar; Ekmedzic, Marko; Milosevic, Jovan; Rekovic, Vladimir; Alcaraz Maestre, Juan; Battilana, Carlo; Calvo, Enrique; Cerrada, Marcos; Chamizo Llatas, Maria; Colino, Nicanor; De La Cruz, Begona; Delgado Peris, Antonio; Domínguez Vázquez, Daniel; Escalante Del Valle, Alberto; Fernandez Bedoya, Cristina; Fernández Ramos, Juan Pablo; Flix, Jose; Fouz, Maria Cruz; Garcia-Abia, Pablo; Gonzalez Lopez, Oscar; Goy Lopez, Silvia; Hernandez, Jose M; Josa, Maria Isabel; Navarro De Martino, Eduardo; Pérez-Calero Yzquierdo, Antonio María; Puerta Pelayo, Jesus; Quintario Olmeda, Adrián; Redondo, Ignacio; Romero, Luciano; Senghi Soares, Mara; Albajar, Carmen; de Trocóniz, Jorge F; Missiroli, Marino; Moran, Dermot; Brun, Hugues; Cuevas, Javier; Fernandez Menendez, Javier; Folgueras, Santiago; Gonzalez Caballero, Isidro; Brochero Cifuentes, Javier Andres; Cabrillo, Iban Jose; Calderon, Alicia; Duarte Campderros, Jordi; Fernandez, Marcos; Gomez, Gervasio; Graziano, Alberto; Lopez Virto, Amparo; Marco, Jesus; Marco, Rafael; Martinez Rivero, Celso; Matorras, Francisco; Munoz Sanchez, Francisca Javiela; Piedra Gomez, Jonatan; Rodrigo, Teresa; Rodríguez-Marrero, Ana Yaiza; Ruiz-Jimeno, Alberto; Scodellaro, Luca; Vila, Ivan; Vilar Cortabitarte, Rocio; Abbaneo, Duccio; Auffray, Etiennette; Auzinger, Georg; Bachtis, Michail; Baillon, Paul; Ball, Austin; Barney, David; Benaglia, Andrea; Bendavid, Joshua; Benhabib, Lamia; Benitez, Jose F; Bloch, Philippe; Bocci, Andrea; Bonato, Alessio; Bondu, Olivier; Botta, Cristina; Breuker, Horst; Camporesi, Tiziano; Cerminara, Gianluca; Colafranceschi, Stefano; D'Alfonso, Mariarosaria; D'Enterria, David; Dabrowski, Anne; David Tinoco Mendes, Andre; De Guio, Federico; De Roeck, Albert; De Visscher, Simon; Di Marco, Emanuele; Dobson, Marc; Dordevic, Milos; Dorney, Brian; Dupont-Sagorin, Niels; Elliott-Peisert, Anna; Franzoni, Giovanni; Funk, Wolfgang; Gigi, Dominique; Gill, Karl; Giordano, Domenico; Girone, Maria; Glege, Frank; Guida, Roberto; Gundacker, Stefan; Guthoff, Moritz; Hammer, Josef; Hansen, Magnus; Harris, Philip; Hegeman, Jeroen; Innocente, Vincenzo; Janot, Patrick; Kortelainen, Matti J; Kousouris, Konstantinos; Krajczar, Krisztian; Lecoq, Paul; Lourenco, Carlos; Magini, Nicolo; Malgeri, Luca; Mannelli, Marcello; Marrouche, Jad; Masetti, Lorenzo; Meijers, Frans; Mersi, Stefano; Meschi, Emilio; Moortgat, Filip; Morovic, Srecko; Mulders, Martijn; Orfanelli, Styliani; Orsini, Luciano; Pape, Luc; Perez, Emmanuelle; Petrilli, Achille; Petrucciani, Giovanni; Pfeiffer, Andreas; Pimiä, Martti; Piparo, Danilo; Plagge, Michael; Racz, Attila; Rolandi, Gigi; Rovere, Marco; Sakulin, Hannes; Schäfer, Christoph; Schwick, Christoph; Sharma, Archana; Siegrist, Patrice; Silva, Pedro; Simon, Michal; Sphicas, Paraskevas; Spiga, Daniele; Steggemann, Jan; Stieger, Benjamin; Stoye, Markus; Takahashi, Yuta; Treille, Daniel; Tsirou, Andromachi; Veres, Gabor Istvan; Wardle, Nicholas; Wöhri, Hermine Katharina; Wollny, Heiner; Zeuner, Wolfram Dietrich; Bertl, Willi; Deiters, Konrad; Erdmann, Wolfram; Horisberger, Roland; Ingram, Quentin; Kaestli, Hans-Christian; Kotlinski, Danek; Langenegger, Urs; Renker, Dieter; Rohe, Tilman; Bachmair, Felix; Bäni, Lukas; Bianchini, Lorenzo; Buchmann, Marco-Andrea; Casal, Bruno; Dissertori, Günther; Dittmar, Michael; Donegà, Mauro; Dünser, Marc; Eller, Philipp; 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2015-06-09
A search for a standard model Higgs boson produced in association with a top-quark pair and decaying to bottom quarks is presented. Events with hadronic jets and one or two oppositely charged leptons are selected from a data sample corresponding to an integrated luminosity of 19.5 fb$^{-1}$ collected by the CMS experiment at the LHC in pp collisions at a centre-of-mass energy of 8 TeV. In order to separate the signal from the larger $\\mathrm{t \\bar{t}}$+jets background, this analysis uses a matrix element method that assigns a probability density value to each reconstructed event under signal or background hypotheses. The ratio between the two values is used in a maximum likelihood fit to extract the signal yield. The results are presented in terms of the measured signal strength modifier, $\\mu$, relative to the standard model prediction for a Higgs boson mass of 125 GeV. The observed (expected) exclusion limit at a 95% confidence level is $\\mu$ lower than 4.2 (3.3), corresponding to a best fit value $\\hat{\\m...
Energy Technology Data Exchange (ETDEWEB)
Erbacher, Robin D.; /UC, Davis
2005-10-01
While the top quark was discovered in 1995 at the Fermilab Tevatron, a decade later they still have very little information about the top. As the heaviest particle yet discovered, the top quark is interesting in and of itself, but some speculate that it may play a special role in physics beyond the Standard Model. With Run 2 of the Tevatron well underway, they have the opportunity to study top quark properties with much better sensitivity, and to test whether top quarks behave as predicted by current theories. This article focuses on the basics of top quark physics at the Tevatron, highlighting only a sample of the many recent measurements, as new results are being released monthly, and constantly changing the landscape of our knowledge of top.
QCD next-to-leading-order predictions matched to parton showers for vector-like quark models.
Fuks, Benjamin; Shao, Hua-Sheng
2017-01-01
Vector-like quarks are featured by a wealth of beyond the Standard Model theories and are consequently an important goal of many LHC searches for new physics. Those searches, as well as most related phenomenological studies, however, rely on predictions evaluated at the leading-order accuracy in QCD and consider well-defined simplified benchmark scenarios. Adopting an effective bottom-up approach, we compute next-to-leading-order predictions for vector-like-quark pair production and single production in association with jets, with a weak or with a Higgs boson in a general new physics setup. We additionally compute vector-like-quark contributions to the production of a pair of Standard Model bosons at the same level of accuracy. For all processes under consideration, we focus both on total cross sections and on differential distributions, most these calculations being performed for the first time in our field. As a result, our work paves the way to precise extraction of experimental limits on vector-like quarks thanks to an accurate control of the shapes of the relevant observables and emphasise the extra handles that could be provided by novel vector-like-quark probes never envisaged so far.
Botella, F. J.; Branco, G. C.; Rebelo, M. N.; Silva-Marcos, J. I.
2016-12-01
We point out that in the standard model there is meaningful quark mixing even in the extreme chiral (EC) limit, where only the third generation of quarks acquires mass. This mixing is in general expected to be of order 1 and the fact that |V13|2+|V23|2≈1.6 ×1 0-3 implies a novel fine-tuning problem in the SM which we point out for the first time. We propose a possible way of avoiding this fine-tuning by introducing a symmetry S which leads to VCKM=1 , with only the third generation of quarks acquiring mass. We consider two scenarios for generating the mass of the first two quark generations and full quark mixing based on the assumption that the masses of the first two quark families are not generated by the standard Higgs. One consists of the introduction of a second Higgs doublet which is neutral under S . The second scenario consists of assuming new physics at a high energy scale, contributing to the masses of light quark generations, in an effective field theory approach. This last scenario leads to couplings of the Higgs particle to s s ¯ and c c ¯ which are significantly enhanced with respect to those of the SM. In both schemes, one has scalar-mediated flavor-changing neutral currents which are naturally suppressed. Flavor-violating top decays are predicted in the second scenario at the level Br (t →h c )≥5 ×1 0-5 .
SU(2 color NJL model and EOS of quark-hadron matter at finite temperature and density
Directory of Open Access Journals (Sweden)
Weise Wolfram
2012-02-01
Full Text Available We study the NJL model with the Polyakov loop in the SU(2-color case for the EOS of quark-hadron matter at finite temperature and density. We consider the spontaneous chiral symmetry breaking and the diquark condensation together with the behavior of the Polyakov loop for the phase diagram of quark-hadron matter. We discuss the spectrum of mesons and diquark baryons (boson at finite temperature and density.We derive also the linear sigma model Lagrangian for diquark baryon and mesons.
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.
Quark-Antiquark and Diquark Condensates in Vacuum in a 3D Two-Flavor Gross-Neveu Model
Bang-Rong, Zhou
2007-01-01
The effective potential analysis indicates that, in a 3D two-flavor Gross-Neveu model in vacuum, depending on less or bigger than the critical value 2/3 of $G_S/H_P$, where $G_S$ and $H_P$ are respectively the coupling constants of scalar quark-antiquark channel and pseudoscalar diquark channel, the system will have the ground state with pure diquark condensates or with pure quark-antiquark condensates, but no the one with coexistence of the two forms of condensates. The similarities and differences in the interplay between the quark-antiquark and the diquark condensates in vacuum in the 2D, 3D and 4D two-flavor four-fermion interaction models are summarized.
Production of Charged Scalars from the Littlest Higgs Model Associated with Top Quark at LHC
Institute of Scientific and Technical Information of China (English)
LIU Wei-Na; LIU Yao-Bei; LI Ping; SHEN Jie-Fen; GOU Qing-Quan; CUI Xiao-Min; ZHAO Yan-Ping; REN Xiao-Yan
2008-01-01
The littlest Higgs (LH) model is the most economical one among various little Higgs models, which predicts the existence of the charged scalars φ±. In this paper, we study the production of the charged Higgs boson φ- with single top quark via the process gb → tφ- at the CERN Large Hadron Collider (LHC). The numerical results show that the production cross section is smaller than 0.2 pb in most of the parameters space, it is very difficult to observe the signatures of the charged scalars via the process pp → gb + X → tφ- + X at the LHC experiments. However, it can open a window to distinguish the top-pions in the TC2 model or charged Higgs in the MSSM from φ±.
Bs→Φπ0 Decay in the Extra Down-Type Quark Model
Institute of Scientific and Technical Information of China (English)
WANG Shuai-wei; HUANG Jin-Shu; L(U) Lin-Xia
2010-01-01
@@ Using the QCD factorization approach,we investigate the electro-weak penguin dominated process Bs→Φπ0in the extra down-type quark(EDQS)model We calculate the effects of new physics(NP)on the branching fraction and direct CP asymmetry of the decay mode.It is found that the branching fraction can be increased by 15% points or dropped by 13% points than the standard model(SM)value,and its direct CP asymmetry can be increased by 35% points or dropped by 37% points than the SM one.The effects of NP on the direct CP asymmetry are more obvious than on the branching fraction.If this decay mode could be measured in the upcoming LHCb experiment,these results we obtain will be useful for further studies of the EDQS model
Evidence for production of single top quarks
Abazov, V.M.; et al., [Unknown; de Jong, S.J.; Demarteau, M.; Houben, P.; van den Berg, P.J.
2008-01-01
We present first evidence for the production of single top quarks in the D0 detector at the Fermilab Tevatron p (p) over bar collider. The standard model predicts that the electroweak interaction can produce a top quark together with an antibottom quark or light quark, without the antiparticle top-q
X (4140 ), X (4274 ), X (4500 ), and X (4700 ) in the relativized quark model
Lü, Qi-Fang; Dong, Yu-Bing
2016-10-01
We investigate the masses of c s c ¯ s ¯ tetraquark states in a diquark-antidiquark picture employing the relativized quark model proposed by Godfrey and Isgur. Only the antitriplet diquark states in color space are calculated. The diquark masses are obtained with the relativized potential first, and then the diquark and antidiquark are treated as the usual antiquark and quark, respectively, and the masses of the tetraquark states are obtained by solving the Schrödinger equation with the relativized potential between the diquark and antidiquark. The theoretical uncertainties induced by screening effects are also taken into account. It is found that the resonance of X (4140 ) can be regarded as the c s c ¯s ¯ tetraquark ground states, and the X (4700 ) can be assigned as the 2 S excited tetraquark state. When the internal excited diquarks are taken into account, the resonance of X (4500 ) can be explained as the tetraquark composed of one 2 S scalar diquark and one scalar antidiquark. In our approach, the X (4274 ) cannot be explained as a tetraquark state; however, it can be a good candidate of the conventional χc 1(3 3P1) state. In addition, other charmoniumlike states χc 0(3915 ), X (4350 ), X (4630 ), and X (4660 ), as the c s c ¯s ¯ tetraquark states, are also discussed.
Relativistic effects on the neutron charge form factor in the constituent quark model
Cardarelli, F
1999-01-01
The neutron charge form factor GEn(Q**2) is investigated within a constituent quark model formulated on the light-front. It is shown that, if the quark initial motion is neglected in the Melosh rotations, the Dirac neutron form factor F1n(Q**2) receives a relativistic correction which cancels exactly against the Foldy term in GEn(Q**2), as it has been recently argued by Isgur. Moreover, at the same level of approximation the ratio of the proton to neutron magnetic form factors GMp(Q**2)/GMn(Q**2) is still given by the naive SU(6)-symmetry expectation, -3/2. However, it is also shown that the full Melosh rotations break SU(6) symmetry, giving rise to GEn(Q**2) neq 0 and GMp(Q**2)/GMn(Q**2) neq -3/2 even when a SU(6)-symmetric canonical wave function is assumed. It turns out that relativistic effects alone cannot explain simultaneously the experimental data on GEn(Q**2) and GMp(Q**2)/GMn(Q**2).
Charged-particle rapidity density in Au+Au collisions in a quark combination model
Shao, Feng-Lan; Yao, Tao; Xie, Qu-Bing
2007-03-01
Rapidity/pseudorapidity densities for charged particles and their centrality, rapidity, and energy dependence in Au+Au collisions at the Relativistic Heavy Ion Collider are studied in a quark combination model. Using a Gaussian-type rapidity distribution for constituent quarks as a result of Landau hydrodynamic evolution, the data at sNN=130,200 GeV at various centralities in full pseudorapidity range are well described, and the charged-particle multiplicities are reproduced as functions of the number of participants. The energy dependence of the shape of the dNch/dη distribution is also described at various collision energies sNN=200,130,62.4 GeV in central collisions with same value of parameters except 19.6 GeV. The calculated rapidity distributions and yields for the charged pions and kaons in central Au+Au collisions at sNN=200 GeV are compared with experimental data of the BRAHMS Collaboration.
Bag model of hadrons, dual QCD thermodynamics and Quark-Gluon Plasma
Chandola, H C; Dehnen, H
2015-01-01
Using the grand canonical ensemble formulation of a multi-particle statistical system, the thermodynamical description of the dual QCD has been presented in terms of the bag model of hadrons and analyzed for the quark-gluon plasma phase of hadronic matter. The dual QCD bag construction has been shown to lead to the radial pressure on the bag surface in terms of the vector glueball masses of the magnetically condensed QCD vacuum. Constructing the grand canonical partition function to deal with the quark-gluon plasma phase of the non-strange hadrons, the energy density and the plasma pressure have been derived and used to understand the dynamics of the associated phase transition. The critical temperature for QGP-hadron phase transition has been derived and numerically estimated by using various thermodynamic considerations. A comparison of the values of the critical temperatures for QGP-hadron phase transition with those obtained for the deconfinement-phase transition, has been shown to lead to the relaxation ...
Properties of single cluster structure of $d^*(2380)$ in chiral SU(3) quark model
Lü, Qi-Fang; Dong, Yu-Bing; Shen, Peng-Nian; Zhang, Zong-Ye
2016-01-01
The structure of $d^*(2380)$ is re-studied with the single cluster structure in the chiral SU(3) quark model which has successfully been employed to explain the scattering and binding behaviors of baryonic systems. The mass and width are explicitly calculated with two types of trial wave functions. The result shows that the $(0s)^6 [6]_{orb}$ configuration is easy to convert to the configuration with the same $[6]_{orb}$ symmetry but $2\\hbar \\omega$ excitation back and forth, however, it is seldom to turn into a two-cluster configuration with a (1s) relative motion in between. The resultant mass and width are about $2394$MeV and $25$MeV, respectively, and the stable size is about $0.75fm$, which are consistent with both the results in the two-cluster configuration calculation and the data measured by the COSY collaboration. It seems that the observed $d^*$ is a six-quark dominated exotic state with a spherical shape and breath mode in the coordinate space. Moreover, if $d^*$ does have $2\\hbar \\omega$ excitati...
The $X(4140)$, $X(4274)$, $X(4500)$ and $X(4700)$ in the relativized quark model
Lü, Qi-Fang
2016-01-01
We investigate the masses of $cs \\bar c \\bar s$ tetraquark states in a diquark-antidiquark picture employing the relativized quark model proposed by Godfrey and Isgur. Only the antitriplet diquark states in color space are calculated. The diquark masses are obtained with the relativized potential firstly, and then the diquark and antidiquark are treated as the usual antiquark and quark, respectively, and the masses of the tetraquark states are obtained by solving the Schr\\"{o}dinger equation with the relativized potential between the diquark and antidiquark. The theoretical uncertainties induced by screening effects are also taken into account. It is found that the resonance of $X(4140)$ can be regarded as the $cs \\bar c \\bar s$ tetraquark ground states, and the $X(4700)$ can be assigned as the $2S$ excited tetraquark state. When the internal excited diquarks are taken into account, the resonance of $X(4500)$ can be explained as the tetraquark composed of one $2S$ scalar diquark and one scalar antidiquark. In...
Institute of Scientific and Technical Information of China (English)
SUN Le-Xue; WANG Rui-Qin; SONG Jun; SHAO Feng-Lan
2012-01-01
The quark combination mechanism of hadron production is applied to nucleus-nucleus collisions at the CERN Super Proton Synchrotron (SPS) and the BNL Alternating Gradient Synchrotron (AGS).The rapidity spectra of identified hadrons and their spectrum widths are studied.The data of π-,K±,φ,A,(A),Ξ- and Ξ+ at 80 and 40 A GeV,and in particular at 30 and 20 A GeV where the onset of deconfinement is suggested to happen,are consistently described by the quark combination model.However,at AGS 11.6 A GeV below the onset,the π±,K± and A spectra cannot be simultaneously explained,indicating the disappearance of the intrinsic correlation of their production in the constituent quark level.The collision-energy dependence of the rapidity spectrum widths of the constituent quarks,and the strangeness of the hot and dense quark matter produced in heavy ion collisions,are obtained and discussed.
Low-Energy Kπ Phase Shifts in Chiral SU(3) Quark Model
Institute of Scientific and Technical Information of China (English)
HUANG Fei; ZHANG Zong-Ye; YU You-Wen
2005-01-01
The low-energy region kaon-pion S- and P-wave phase shifts with isospin I = 1/2 and I = 3/2 are dynamically studied in the chiral SU(3) quark model by solving a resonating group method equation. The model parameters are taken to be the values fitted by the energies of the baryon ground states and the kaon-nucleon elastic scattering phase shifts of different partial waves. As a preliminary study the s-channel q(-q) annihilation interactions are not included since they only act in the very short range and are subsequently assumed to be unimportant in the low-energy domain. The numerical results are in qualitative agreement with the experimental data.
Constituent Quarks and Gluons, Polyakov loop and the Hadron Resonance Gas Model ***
Megías, E.; Ruiz Arriola, E.; Salcedo, L. L.
2014-03-01
Based on first principle QCD arguments, it has been argued in [1] that the vacuum expectation value of the Polyakov loop can be represented in the hadron resonance gas model. We study this within the Polyakov-constituent quark model by implementing the quantum and local nature of the Polyakov loop [2, 3]. The existence of exotic states in the spectrum is discussed. Presented by E. Megías at the International Nuclear Physics Conference INPC 2013, 2-7 June 2013, Firenze, Italy.Supported by Plan Nacional de Altas Energías (FPA2011-25948), DGI (FIS2011-24149), Junta de Andalucía grant FQM-225, Spanish Consolider-Ingenio 2010 Programme CPAN (CSD2007-00042), Spanish MINECO's Centro de Excelencia Severo Ochoa Program grant SEV-2012-0234, and the Juan de la Cierva Program.
Pion-cloud effects on the electromagnetic properties of nucleons in a quark model
Energy Technology Data Exchange (ETDEWEB)
Barik, N. (Utkal Univ., Bhubaneswar (India). Dept. of Physics); Jena, S.N. (Berhampur Univ. (India). Dept. of Physics); Rath, D.P. (Dept. of Physics, Aska Science College, ASKA-761110, Orissa (India))
1992-10-30
This paper reports that incorporating corrections for the center-of-mass motion and pion-cloud effects the nucleon electromagnetic form factors G[sup N][sub E.M] (q[sup 2]) are computed in an independent quark model based on the Dirac equation with a confining potential V[sub q](r) = (1 + [gamma][sup 0]) a 1n (r/b). The static quantities like magnetic moment [mu]n, charge radius (r[sup 2]) [sup 1/2][sub N] and axial vector coupling constant (g[sub A])[sub n [r arrow] pev] of the nucleons computed in this model are in reasonable agreement with the experiment. The pseudoscalar and the pseudovector pion-nucleon coupling constants are obtained as g[sub NN[pi
Pion scattering and electro-production on nucleons in the resonance region in chiral quark models
Sirca, Simon; Fiolhais, Manuel; Alberto, Pedro
2011-01-01
Pion scattering and electro-production amplitudes have been computed in a coupled-channel framework incorporating quasi-bound quark-model states, based on the Cloudy Bag model. All relevant low-lying nucleon resonances in the P33, P11, and S11 partial waves have been covered, including the Delta(1232), the N*(1440), N*(1535), and N*(1650). Consistent results have been obtained for elastic and inelastic scattering (two-pion, eta-N, and K-Lambda channels), as well as for electro-production. The meson cloud has been shown to play a major role, in particular in electro-magnetic observables in the P33 and P11 channels.
Semileptonic decays of Λ{sub c} baryons in the relativistic quark model
Energy Technology Data Exchange (ETDEWEB)
Faustov, R.N.; Galkin, V.O. [Institute of Informatics in Education, FRC CSC RAS, Moscow (Russian Federation)
2016-11-15
Motivated by recent experimental progress in studying weak decays of the Λ{sub c} baryon we investigate its semileptonic decays in the framework of the relativistic quark model based on the quasipotential approach with the QCD-motivated potential. The form factors of the Λ{sub c} → Λlν{sub l} and Λ{sub c} → nlν{sub l} decays are calculated in the whole accessible kinematical region without extrapolations and additional model assumptions. Relativistic effects are systematically taken into account including transformations of baryon wave functions from the rest to moving reference frame and contributions of the intermediate negative-energy states. Baryon wave functions found in the previous mass spectrum calculations are used for the numerical evaluation. Comprehensive predictions for decay rates, asymmetries and polarization parameters are given. They agree well with available experimental data. (orig.)
Flavor-changing decays of the top quark in 5D warped models
Díaz-Furlong, Alfonso; Frank, Mariana; Pourtolami, Nima; Toharia, Manuel; Xoxocotzi, Reyna
2016-08-01
We study flavor-changing neutral current decays of the top quark in the context of general warped extra dimensions, where the five-dimensional (5D) metric is slightly modified from 5D anti-de Sitter (AdS5 ). These models address the Planck-electroweak hierarchies of the Standard Model and can obey all the low-energy flavor bounds and electroweak precision tests, while allowing the scale of new physics to be at the TeV level, and thus within the reach of the LHC at Run II. We perform the calculation of these exotic top decay rates for the case of a bulk Higgs, and thus include in particular the effect of the additional Kaluza-Klein (KK) Higgs modes running in the loops, along with the usual KK fermions and KK gluons.
Properties of light ﬂavour baryons in hypercentral quark model
Indian Academy of Sciences (India)
Kaushal Thakkar; Bhavin Patel; Ajay Majethiya; P C Vinodkumar
2011-12-01
The light ﬂavour baryons are studied within the quark model using the hypercentral description of the three-body system. The conﬁnement potential is assumed as hypercentral Coulomb plus power potential (hCPP ) with power index . The masses and magnetic moments of light ﬂavour baryons are computed for different power indices, , starting from 0.5 to 1.5. The predicted masses and magnetic moments are found to attain a saturated value with respect to variation in beyond the power index > 1.0. Further, we computed transition magnetic moments and radiative decay width of light ﬂavour baryons. The results are in good agreement with the known experimental as well as other theoretical models.
Inverse magnetic catalysis and regularization in the quark-meson model
Andersen, Jens O; Tranberg, Anders
2014-01-01
Motivated by recent work on inverse magnetic catalysis at finite temperature, we study the quark-meson model using both dimensional regularization and a sharp cutoff. We calculate the critical temperature for the chiral transition as a function of the Yukawa coupling in the mean-field approximation varying the renormalization scale and the value of the ultraviolet cutoff. We show that the results depend sensitively on how one treats the fermionic vacuum fluctuations in the model and in particular on the regulator used. Finally, we explore a $B$-dependent transition temperature for the Polyakov loop potential $T_0(B)$ using the functional renormalization group. These results show that even arbitrary freedom in the function $T_0(B)$ does not allow for a decreasing chiral transition temperature as a function of $B$. This is in agreement with previous mean-field calculations.
Pentaquarks in a relativistic quark model and nature of Theta-states
Gerasyuta, S M
2003-01-01
The relativistic five-quark equations are found in the framework of the dispersion relation technique. The solutions of these equations using the method based on the extraction of the leading singularities of the amplitudes are obtained. The five-quark amplitudes for the low-lying pentaquarks including the u, d, s- quarks are calculated. The poles of these amplitudes determine the masses of Theta-pentaquarks. The mass spectra of the isotensor Theta-pentaquarks are calculated.
Guichon, P A M; Thomas, A W
1996-01-01
We describe the development of a theoretical description of the structure of finite nuclei based on a relativistic quark model of the structure of the bound nucleons which interact through the (self-consistent) exchange of scalar and vector mesons.
Silva, A; Urbano, D; Göke, K; Silva, Antonio; Kim, Hyun-CHul; Urbano, Diana; Goeke, Klaus
2005-01-01
We investigate three different axial-vector form factors of the nucleon, $G_A^{0}$, $G_A^3$, $G_A^8$, within the framework of the SU(3) chiral quark-soliton model, emphasizing their strangeness content. We take into account the rotational $1/N_c$ and linear strange quark ($m_s$) contributions using the symmetry-conserving SU(3) quantization and assuming isospin symmetry. The strange axial-vector form factor is also obtained and they all are discussed in the context of the parity-violating scattering of polarized electrons off the nucleon and its relevance to the strange vector form factors.
OZI violation in low energy omega and phi production in the pp system in a quark-gluon model
Dillig, M
2006-01-01
We investigate OZI violation in near-threshold omega and phi production in the pp system. Assuming ideal omega/phi mixing (corrections are estimated), the energy dependence of the ratio R(omega/phi) is analyzed in a perturbative quark-gluon exchange model up to the third other in the strong coupling constant alpha(s) with the proton represented as a quark - scalar diquark system. We give a very natural explanation of the violation of the OZI rule in omega/phi production and its energy dependence near the production thresholds.
Wang, Wenyu; Xiong, Zhao-Hua; Zhao, Xin-Yan
2016-09-01
In models with vector-like quark doublets, the mass matrices of up and down type quarks are related. Precise diagonalization of the mass matrices has become an obstacle in numerical studies. In this work we first propose a diagonalization method. As its application, in the Standard Model with one vector-like quark doublet we present the quark mass spectrum and Feynman rules for the calculation of B → Xsγ. We find that i) under the constraints of the CKM matrix measurements, the mass parameters in the bilinear term are constrained to a small value by the small deviation from unitarity; ii) compared with the fourth generation extension of the Standard Model, there is an enhancement to the B → Xsγ process in the contribution of vector-like quarks, resulting in a non-decoupling effect in such models. Supported by Natural Science Foundation of China (11375001) and Talents Foundation of Education Department of Beijing