共查询到20条相似文献,搜索用时 46 毫秒
1.
S. R. Cotanch I. J. General P. Wang 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):656-661
The Coulomb gauge Hamiltonian model is used to calculate masses for selected JPC states consisting of exotic combinations of quarks and gluons: ggg glueballs (oddballs), qˉg hybrid mesons and qˉqˉ tetraquark systems. An odderon Regge trajectory is computed for the J- glueballs with intercept much smaller than the pomeron, explaining its nonobservation. The lowest 1-+ hybrid-meson mass is found to be just above 2.2GeV while the lightest tetraquark state mass with these exotic quantum numbers
is predicted around 1.4GeV consistent with the observed π(1400). 相似文献
2.
F. Buisseret C. Semay V. Mathieu B. Silvestre-Brac 《The European Physical Journal A - Hadrons and Nuclei》2007,32(2):123-126
In the framework of quark models, hybrid mesons are either seen as two-body qˉ systems with an excited flux tube connecting the quark to the antiquark or as three-body qˉg systems including a constituent gluon. In this work we show that, starting from the three-body wave function of the qˉg hybrid meson in which the gluonic degrees of freedom are averaged, the excited flux tube picture emerges as an equivalent
qˉ potential. This equivalence between the excited flux tube and the constituent-gluon approach is confirmed for heavy hybrid
mesons but, for the first time, it is shown to hold in the light sector too, provided the contribution of the quark dynamics
is correctly taken into account. 相似文献
3.
4.
Discussed is how non-perturbative properties of quark gluon plasma, recently discovered in RHIC experiment, can be related to the change of properties of scalar and pseudoscalar glueballs. We set up a model with the Cornwall–Soni's glueball–gluon interaction, which shows that the pseudoscalar glueball becomes massless above the critical temperature of deconfinement phase transition. This change of properties gives rise to the change of sign of the gluon condensate at T>Tc. We discuss the other physical consequences resulting from the drastic change of the pseudoscalar glueball mass above the critical temperature. 相似文献
5.
P.C. Vinodkumar J.N. Pandya V.M. Bannur S.B. Khadkikar 《The European Physical Journal A - Hadrons and Nuclei》1999,4(1):83-90
The masses of mesons and baryons with various flavour combinations for qˉq, qˉQ, QˉQ, qqq, qqQ, qQQ, QQQ etc. are computed using a confinement scheme based on harmonic approximation with Lorentz scalar plus vector character. The
residual two body coulombic interactions and the spin-hyperfine interactions of the confined one gluon exchange effects are
perturbatively calculated and added to the confinement energy to get the mass of the hadron. With all the parameters fixed
to get ground state masses of hadrons containing like flavour combinations, a parameter free prediction of the leptonic decaywidths
of vector mesons and their sizes are being made. Our results on the baryonic and mesonic masses with open flavours and the
predictions on the leptonic decay widths are in good agreement with the respective experimental values.
Received: 26 February 1998 / Revised version: 1 September 1998 相似文献
6.
Using a constituent-quark model we study possible bound or resonance Nˉ states. The model fits the pˉ and pˉ cross-sections and explains the large 3
P
0 antiprotonium energy shift. Only a resonance is found in the 3
P
0
I = 0 partial wave. The threshold enhancement in the J/Ψ→γpˉ decay can be explained with FSI effects in S-waves and no Nˉ bound state is needed. 相似文献
7.
Gui-Jun Ding Rong-Gang Ping Mu-Lin Yan 《The European Physical Journal A - Hadrons and Nuclei》2006,28(3):351-360
X(1835) has been treated as a baryonium with sizable gluon content, and to be almost flavor singlet. This picture allows us
to rationally understand X(1835) production in J/ψ radiative decays, and its large couplings with pˉ, η′ππ. The processes ϒ(1S) → γX(1835) and J/ψ → ωX(1835) have been examined. It has been found that Br(ϒ(1S) → γX(1835))Br(X(1835) → pˉ) < 6.45×10-7, which is compatible with CLEO's recent experimental result (Phys. Rev. D 73, 032001 (2006) hep-ex/0510015). The branching fractions Br(J/ψ → ωX(1835)), Br(J/ψ → ρX(1835)) with X(1835) → pˉ and X(1835) → η′π+π- have been estimated by the quark-pair creation model. We show that they are heavily suppressed, so the signal of X(1835) is very difficult, if not impossible, to be observed in these processes. The experimental checks for these estimations
are expected. The existence of the baryonium nonet is conjectured, and a model-independent derivation of their production
branching fractions is presented. 相似文献
8.
The lattice QCD studies indicate that the critical temperature T
c ≃ 260-280 MeV of the deconfinement phase transition in quenched QCD is considerably smaller than the lowest-lying glueball
mass m
G ≃ 1500-1700 MeV, i.e., T
c ≪ m
G. As a consequence of this large difference, the thermal excitation of the glueball in the confinement phase is strongly suppressed
by the statistical factor e
-mG/Tc ≃ 0.00207 even near T ≃ T
c. We consider its physical implication, and argue the abnormal feature of the deconfinement phase transition in quenched QCD
from the statistical viewpoint. To appreciate this, we demonstrate a statistical argument of the QCD phase transition using
the recent lattice QCD data. From the phenomenological relation between T
c and the glueball mass, the deconfinement transition is found to take place in quenched QCD before a reasonable amount of
glueballs is thermally excited. In this way, quenched QCD reveals a question “what is the trigger of the deconfinement phase
transition ?”
Received: 18 November 2002 / Accepted: 4 February 2003 / Published online: 29 April 2003 相似文献
9.
Yu.S. Surovtsev D. Krupa M. Nagy 《The European Physical Journal A - Hadrons and Nuclei》2002,15(3):409-416
In a combined analysis of the experimental data on the coupled processes ππ↦ππ, KˉK in the channel with I
G
J
PC = 0+0+ +, the various scenarios of these reactions (with different numbers of resonances) are considered. In a model-independent approach,
based only on analyticity and unitarity, a resonance is represented by a pole cluster (poles on the Riemann surface) of the
definite type that is defined by the state nature. The best scenario contains the resonances f
0(665) (with properties of the σ-meson), f
0(980) (with a dominant sˉs component), f
0(1500) (with a dominant flavour-singlet, e.g., glueball component) and the f
0(1710) (with a considerable sˉs component). If the f
0(1370) exists, it has a dominant sˉs component. The coupling constants of the observed states with the considered channels and the ππ and KˉK scattering lengths are obtained. The conclusion on the linear realization of chiral symmetry is drawn.
Received: 25 April 2002 / Accepted: 4 June 2002 / Published online: 26 November 2002
RID="a"
ID="a"e-mail: surovcev@thsun1.jinr.ru
RID="b"
ID="b"e-mail: krupa@savba.sk
RID="c"
ID="c"e-mail: fyzinami@nic.savba.sk
Communicated by V.V. Anisovich 相似文献
10.
S. Pomp G. Ingelman T. Johansson S. Ohlsson 《The European Physical Journal A - Hadrons and Nuclei》2002,15(4):517-522
The observed polarisation of Λ hyperons from the inclusive pA → ΛX reaction at high energies has previously been well described within the Lund string model through polarised sˉs quark pair production in the string breaking hadronisation process. This model is here applied to the exclusive ˉpp → ˉΛΛ reaction at low energies and compared to available data sets down to an incident-beam momentum of 1.835 GeV/c. This required an extension of the diquark scattering model to involve three components: an isotropic part relevant close
to the threshold, a spectator part and a forward-scattering part as in pA → ΛX at high energies. The observed angular distributions are then reproduced and, for momentum transfers above | t'| = 0.2 GeV2, agreement with the measured polarisation is also obtained.
Received: 2 April 2002 / Accepted: 24 July 2002 / Published online: 3 December 2002
RID="a"
ID="a"Present address: Department of Neutron Research, Uppsala University, Box 525, S-75120 Uppsala, Sweden; e-mail: Stephan.Pomp@tsl.uu.se.
RID="b"
ID="b"Present address: ESRF, F-38043 Grenoble, France.
Communicated by A. Sch?fer 相似文献
11.
M. Zielinski D. Berg C. Chandlee S. Cihangir T. Ferbel J. Huston T. Jensen F. Lobkowicz T. Ohshima P. Slattery P. Thompson B. Collick S. Heppelmann M. Marshak E. Peterson K. Ruddick A. Jonckheere C. A. Nelson Jr. 《Zeitschrift fur Physik C Particles and Fields》1986,31(4):545-548
Using data on coherent production of π+π+π- systems in π+ collisions with nuclei we exclude the existence ofJ PC=1?+,I=1, exotic hybrid mesons with masses below 1.5 GeV and widths greater than 20 MeV, provided that their primary coupling is to πρ systems. Hybrid states with just such properties have recently been predicted from arguments based on QCD sum rules. Our experimental limit is based on Primakoff production of these states, and on an argument using vector dominance to relate their radiative widths to πρ channels. There has been increasing interest of late in the existence of hybrid states, which, in the case of mesons, contain a valence gluon in addition to aq \(\bar q\) pair in a color-octet state [1–5]. The pursuit of spectroscopic gluon degrees of freedom has been strongly motivated by the general QCD picture of hadrons, as well as by many specific calculations based on QCD sum rules, lattice simulations, and more phenomenological approaches such as QCD-bag models. Although much effort, both thoretical and experimental, has been devoted to the spectroscopy of glueballs, for which several candidates exist [6], it has also been realized that hybrid states may be as amenable to discovery, and perhaps less ambiguous to interpretation. 相似文献
12.
We suggest looking for pure gluon hadronic states (glueballs) in ?→ 3g → low spherically final state (collinear gluon jets). In these events one gluon has the maximum energy, , favouring fragmentation into a glueball. The signature for a true C = G + glueball is its prominence at the ? resonance in e+e? →? → (glueball → four charged pions) + … and its absence in q jets off (we do not expect significant quark fragmentation into glueballs). 相似文献
13.
14.
Glueballs and other resonances with large gluonic components are predicted as bound states by Quantum Chromodynamics (QCD). The lightest (scalar) glueball is estimated to have a mass in the range from 1 to 2 GeV/c2; pseudoscalar and tensor glueballs are expected at higher masses. Many different experiments exploiting a large variety of production mechanisms have presented results in recent years on light mesons with JPC=0++, 0−+, and 2++ quantum numbers. This review looks at the experimental status of glueballs. Good evidence exists for a scalar glueball which is mixed with nearby mesons, but a full understanding is still missing. Evidence for tensor and pseudoscalar glueballs are weak at best. Theoretical expectations of phenomenological models and QCD on the lattice are briefly discussed. 相似文献
15.
J. Vijande G. Krein A. Valcarce 《The European Physical Journal A - Hadrons and Nuclei》2009,40(1):89-97
We perform a quark model calculation of the quarkonia b
and c
spectra using smooth and sudden string breaking potentials. The screening parameter is scale dependent and can be related
to an effective running gluon mass that has a finite infrared fixed point. A temperature dependence for the screening mass
is motivated by lattice QCD simulations at finite temperature. Qualitatively different results are obtained for quarkonia
properties close to a critical value of the deconfining temperature when a smooth or a sudden string breaking potential is
used. In particular, with a sudden string breaking potential quarkonia radii remain almost independent of the temperature
up to the critical point, only well above the critical point the radii increase significantly. Such a behavior will impact
the phenomenology of quarkonia interactions in medium, in particular for scattering dissociation processes. 相似文献
16.
We analyze two recent reactions of Belle, producing Dˉ and Dˉ* states that have an enhancement of the invariant Dˉ , Dˉ* mass distribution above threshold, from the point of view that they might be indicative of the existence of a hidden charm
scalar and an axial vector meson state below Dˉ or Dˉ* thresholds, respectively. We conclude that the data is compatible with the existing prediction of a hidden charm scalar meson
with mass around 3700MeV, though other possibilities cannot be discarded. The peak seen in the Dˉ* spectrum above threshold is, however, unlikely to be due to a threshold enhancement produced by the presence, below threshold,
of the hidden charm axial vector meson X(3872) . 相似文献
17.
The mass spectra of the excited heavy baryons consisting of two light (u,d,s) and one heavy (c,b) quarks are calculated in the heavy-quark–light-diquark approximation within the constituent quark model. The light quarks, forming the diquark, and the light diquark in the baryon are treated completely relativistically. The expansion in v/c up to the second order is used only for the heavy (b and c) quarks. The internal structure of the diquark is taken into account by inserting the diquark–gluon interaction form factor. An overall good agreement of the obtained predictions with available experimental data is found. 相似文献
18.
19.
M. P. Lombardo M. L. Paciello S. Petrarca B. Taglienti 《The European Physical Journal C - Particles and Fields》2008,58(1):69-81
We present the first results on scalar glueballs in cold, dense matter using lattice simulations of two-color QCD. The simulations
are carried out on a 63×12 lattice and use a standard hybrid molecular dynamics algorithm for staggered fermions for two values of quark mass. The
glueball correlators are evaluated via a multi-step smearing procedure. The amplitude of the glueball correlator peaks in
correspondence with the zero temperature chiral transition, μ
c=m
π
/2, and the propagators change in a significant way in the superfluid phase, while the Polyakov loop is nearly insensitive
to the transition. Standard analysis suggest that lowest mass in the 0++ gluonic channel decreases in the superfluid phase, but these observations need to be confirmed on larger and more elongated
lattices. These results indicate that a non-zero density induces non-trivial modifications of the gluonic medium. 相似文献
20.
A. Majethiya B. Patel P. C. Vinodkumar 《The European Physical Journal A - Hadrons and Nuclei》2008,38(3):307-315
Properties of single heavy flavor baryons in a non-relativistic potential model with colour Coulomb plus a power law confinement
potential have been studied using a simple variational method. The ground-state masses of single heavy baryons and the mass
difference between the J
P =
+ and J
P =
+ states are computed using a spin-dependent two-body potential. Using the spin-flavour structure of the constituting quarks
and by defining an effective confined mass of the constituent quarks within the baryons, the magnetic moments are computed.
The masses and magnetic moments of the single heavy baryons are found to be in accordance with the existing experimental values
and with other theoretical predictions. It is found that an additional attractive interaction of the order of -200 MeV is
required for the antisymmetric states of (Q
c, b) . It is also found that the spin-hyperfine interaction parameters play a decisive role in hadron spectroscopy. 相似文献