arXiv subjects

Mu-Lin Yan

Publications and source records attributed to Mu-Lin Yan.

At least 37 records · Page 2Linked to original sources

arXiv2008

Canonical Charmonium Interpretation for Y(4360) and Y(4660)

In this work, we consider the canonical charmonium assignments for Y(4360) and Y(4660). Y(4660) is good candidate of $\rm 5 ^3S_1$ $c\bar{c}$ state, the possibility of Y(4360) as a $\rm 3 ^3D_1$ $c\bar{c}$ state is studied, and the charmonium hybrid interpretation of Y(4360) can not be excluded completely. We evaluate the $e^{+}e^{-}$ leptonic widths, E1 transitions, M1 transitions and the open flavor strong decays of Y(4360) and Y(4660). Experimental tests for the charmonium assignments are suggested.

hep-ph↗

arXiv2007

A note on the mass splitting of K*(892)

Belle Collaboration reported a new observed value of K*-(892) mass by studying tau --> K_S pi nu_tau decay, which is significantly different from the current world average value given by Particle Data Group 2006. Motivated by this new data, we revisit the issue on the K*0(892)-K*+(892) mass splitting. Our theoretical estimation favors the new measurement by Belle Collaboration. Therefore further experimental efforts are urgently needed to improve our understanding of these issues.

hep-ph↗

arXiv2007

Y(2175): Distinguish Hybrid State from Higher Quarkonium

The possibility of Y(2175) as a $2{^3D_1}$ $s\bar{s}$ meson is studied. We study the decay of $2{^3D_1}$ $s\bar{s}$ from both the $^3P_0$ model and the flux tube model, and the results are similar in the two models. We show that the decay patterns of $1^{--}$ strangeonium hybrid and $2{^3D_1}$ $s\bar{s}$ are very different. The experimental search of the decay modes $KK$, $K^{*}K^{*}$, $K(1460)K$, $h_1(1380)η$ is suggested to distinguish the two pictures. Measuring the $K^{*}K^{*}$ partial width ratios is crucial to discriminate the $2{^3D_1}$ from the $3{^3S_1}$ $s\bar{s}$ assignment.

hep-ph↗

arXiv2007

Unparticle Physics in DIS

The unparticle stuff scenario related to the notrivial IR fixed point in 4D-conformal field theory is recently suggested by Georgi. We illustrate its physical effects in Deep Inelastic Scattering (DIS) process. A possible signal of unparticle related to parity violation asymmetry in DIS is investigated. It is found out that the behavior of this parity violation signal is sensitive to the value of the scale dimension $d_{\cal U}$ of unpaticle.

hep-ph↗

arXiv2007

A Candidate for $1^{--}$ Strangeonium Hybrid

We propose that the recently observed structure at 2175MeV by the Babar Collaboration is a $1^{--}$ strangeonium hybrid, and we investigate this interpretation from both the flux tube model and the constituent gluon model. The decay patterns and decay width in the flux tube model and the constituent gluon model (for the "gluon excited" hybrid) are very similar. The tetraquark hypothesis is not favored by the available experimental data. The crucial test of our scenario is suggested, furthermore, the promising channels which can discriminate the hybrid interpretation from the tetraquark are also suggested.

hep-ph↗

arXiv2007

Variation of the Fine-Structure Constant from the de Sitter Invariant Special Relativity

There are obvious discrepancies among various experimental constraints on the variation of the fine-structure constant, $α$. We attempt to discuss the issue in the framework of de Sitter invariant Special Relativity (${\cal SR}_{c,R}$) and to present a possible solution to the disagreement. In addition, on the basis of the observational data and the discussions presented in this Letter, we derive a rough theoretical estimate of the radius of the Universe.

astro-ph↗

arXiv2007

Nucleon-antinucleon Interaction from the Modified Skyrme Model

We calculate the static nucleon-antinucleon interaction potential from the modified Skyrme model with additional $B^μB_μ$ term using the product ansatz. The static properties of single baryon are improved in the modified Skyrme model. State mixing is taken into account by perturbation theory, which substantially increases the strength of the central attraction. We obtain a long and mid range potential which is in qualitative agreement with some phenomenological potentials.

nucl-th↗

arXiv2006

Hamiltonian Formalism of the de-Sitter Invariant Special Relativity

Lagrangian of the Einstein's special relativity with universal parameter $c$ ($\mathcal{SR}_c$) is invariant under Poincaré transformation which preserves Lorentz metric $η_{μν}$. The $\mathcal{SR}_c$ has been extended to be one which is invariant under de Sitter transformation that preserves so called Beltrami metric $B_{μν}$. There are two universal parameters $c$ and $R$ in this Special Relativity (denote it as $\mathcal{SR}_{cR}$). The Lagrangian-Hamiltonian formulism of $\mathcal{SR}_{cR}$ is formulated in this paper. The canonic energy, canonic momenta, and 10 Noether charges corresponding to the space-time's de Sitter symmetry are derived. The canonical quantization of the mechanics for $\mathcal{SR}_{cR}$-free particle is performed. The physics related to it is discussed.

hep-th↗

arXiv2006

Backward Compton Scattering in Strong Uniform Magnetic Field

In strong uniform magnetic field, the vacuum Non-Commutative Plane (NCP) caused by the lowest Landau level(LLL) effect and the QED with NCP (QED-NCP) are studied. Being similar to the theory of Quantum Hall effect, an effective filling factor $f(B)$ is introduced to character the possibility that the electrons stays on LLL. The backward Compton scattering amplitudes of QED-NCP are derived, and the differential cross sections for the process with polarized initial electrons and photons are calculated. The existing Spring-8's data has been analyzed primitively and some hints for QED-NCP effects are shown. We propose to precisely measure the differential cross sections of the backward Compton scattering in perpendicular magnetic field experimentally, which may lead to reveal the effects of QED-NCP. PACS number: 12.20.Ds; 11.10.Nx; 71.70.Di; 73.43.Fj.

hep-ph↗

arXiv2006

X(1576) as Diquark-Antidiquark Bound State

We propose that the broad $1^{--}$ resonance structure recently discovered by BES in $J/ψ\to K^{+}K^{-}π^{0}$ is the P-wave excitation of a diquark-antidiquark bound state. This interpretation implies that there exists a negative parity, vector nonet. A rough estimate of the mass spectrum of the nonet is presented, and the prediction for the mass of X(1576) is consistent with the experimental data. The OZI allowed strong decays are studied, it can decay into two pseudoscalars or one pseudoscalar plus one vector meson. A crucial prediction is that X(1576) should dominantly decay into $K^{+}K^{-}$, $K_{L}K_{S}$, $ϕπ^{0}$. Since the isospin of X(1576) is $\mathbf{1}$, the observation of $I_3=1$ or $I_3=-1$ states which predominantly decays into strange mesons could provide another important test to our proposal. To search the charged $I_3=1$ isospin partner associated with X(1576) in $J/ψ\to ηπ^{+}π^{-}$, $J/ψ\to K^{+}K_{L}π^{-}$, $J/ψ\to K^{+}K_{S}π^{-}$, $J/ψ\to ϕπ^{+}π^{-}$ is suggested.

hep-ph↗

arXiv2006

Spectroscopy of $\rm{q}^3\bar{\rm{q}}^3$-States in Quark Model and Baryon-Antibaryon Enhancements

We study the mass spectrum of the $\rm{q}^3\bar{\rm{q}}^3$ mesons both from the quark model with triquark correlations and from common quark model with colormagnetic interactions and with relative S-waves between quarks. Two cluster configurations $(\rm{q}^3)-(\bar{\rm{q}}^3)$ and $(\rm{q}^2\bar{\rm{q}})-(\rm{q}\bar{\rm{q}}^2)$ are considered. In the spectrum we find rather stable states which have the same quantum number with particle resonances which are corresponding to the $p\bar{p}$ enhancement, $p\barΛ$ enhancement and $Λ\barΛ$ enhancement with spin-$\mathbf{0}$ or $\mathbf{1}$. This imply these enhancements are NOT experimental artifacts. The color-spin-flavor structures of $p\bar{p}$, $p\barΛ$, and $Λ\barΛ$ enhancements are revealed. The existence of spin-$\mathbf{1}$ $Λ\barΛ, p\barΛ, p\bar{p}$ enhancements is predicted.

hep-ph↗

arXiv2006

Productions of X(1835) as baryonium with sizable gluon content

The 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 $p\bar{p}$, $η^{\prime}ππ$. The processes $Υ(1S)\to γX(1835)$ and $J/ψ\to ωX(1835)$ have been examined. It has been found that $Br(Υ(1S)\toγX(1835))Br(X(1835)\to p\bar{p})<6.45\times10^{-7}$, which is compatible with CLEO's recently experimental result (Phys.Rev.$\mathbf{D73}$ (2006) 032001;hep-ex/0510015). The branching fractions of $Br(J/ψ\toωX(1835))$, $Br(J/ψ\toρX(1835))$ with $X(1835)\to p\bar{p}$ and $X(1835)\toη^{\prime}π^{+}π^{-}$ 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.

hep-ph↗

arXiv2006

X(1835) as Proton-Antiproton Bound State in Skyrme Model

We present a review to the recent works related to interpreting the exotic particle X(1835) reported by BES as a $N\bar{N}$-baryonium in the Skyrme model. There are two evidences that support this interpretation: 1) There exist a classical $N\bar{N}$-Skyrmion solution with about $\sim 10$MeV binding energies in the model; 2) The decay of this Skymion-baryonium is caused by annihilation of $p-\bar{p}$ inside X(1835) through the quantum tunneling effect, and hence the most favorable decay channels are $X\to η4π$ or $X\to η' 2π$. These lead to reasonable interpreting the data of BES, and especially to useful prediction on the decay mode of X(1835) for the experiment.

hep-ph↗

arXiv2005

Baryonium with a phenomenological skyrmion-type potential

In this paper, we investigate the nucleon-antinucleon static energies in the Skyrme model with the product {\it Anzatz}. The calculation shows that in the ungroomed $S\bar S$ (skyrmion and antiskyrmion) channel, which leads to rapid annihilation, there exists a quasi-stable bound state which may give a natural explanation for the near-threshold enhancement in the proton-antiproton $(p\bar{p})$ mass spectrum reported by the BES Collaboration and the Belle Collaboration. Similar to the phenomenological well potential of the deuteron, we construct a phenomenological skyrmion-type potential to study this narrow $p\bar{p}$-resonance in $ J/ψ\to γp\bar{p}$. By this potential model, a $p\bar{p}$ baryonium with small binding energies is suggested and the decay width of this state is calculated by WKB approximation. In this picture the decay is attributed to quantum tunnelling and $p\bar{p}$ annihilation. Prediction on the decay mode from the baryonium annihilation at rest is also pointed out.

hep-ph↗

arXiv2005

Diquark in Nona-quark States

We study the nonaquark states $S^0(3115)$ and $S^+(3140)$ which are reported by KEK-PS (Phys.Lett. B597 (2004) 236; nucl-ex/0310018) by means of the quark model with diquark correlation. The nonaquark states form $\bf{1},\bf{8},\bf{10},\bar{\bf{10}},\bf{27},\bar{\bf{35}}$ SU(3) multiplets. The flavor wave functions of all the nonaquark states are constructed through the standard tensor technique. The mass spectrum is studied by using Gell-Mann-Okubo mass formula. Some nonaquark mass sum rules are obtained. We further investigate the decay of $S^0(3115)$ and $S^+(3140)$ under the assumption of "fall-apart" mechanism. It has been found that the main decay mode is $ΣNN$ rather than $ΛNN$ which is consistent with experiment. Also we have uniquely determine the flavor wave function of $S^0(3115)$ which belong to $\bf{27}$-plet with the quantum number $Y=2,I=1,I_z=-1$. Whereas the exotic states $S^+(3140)$ can belong to either $\bf{27}$-plet or $\bar{\bf{35}}$-plet. In the exact $SU(3)^{flavor}\times SU(3)^{color}\times SU(2)^{spin}$ limit, both $S^0(3115)$ and $S^+(3140)$ belong to ${\bf 27}$-plet with negative parity. We predict that its flavor structure can be determined by measuring the branch fractions of its decay channels. The experiments to check this prediction are expected.

hep-ph↗

arXiv2005

Proton-Antiproton Annihilation in Baryonium

A possible interpretation of the near-threshold enhancement in the $(p\bar{p})$-mass spectrum in $J/ψ{\to}γp{\bar p}$ is the of existence of a narrow baryonium resonance X(1860). Mesonic decays of the $(p\bar{p})$-bound state X(1860) due to the nucleon-antinucleon annihilation are investigated in this paper. Mesonic coherent states with fixed $G$-parity and $P$-parity have been constructed . The Amado-Cannata-Dedoder-Locher-Shao formulation(Phys Rev Lett. {\bf 72}, 970 (1994)) is extended to the decays of the X(1860). By this method, the branch-fraction ratios of $Br(X\to η4π)$, $Br(X\to η2π)$ and $Br(X\to 3η)$ are calculated. It is shown that if the X(1860) is a bound state of $(p\bar{p})$, the decay channel ($X\to η4π)$ is favored over $(X\to η2π)$. In this way, we develop criteria for distinguishing the baryonium interpretation for the near-threshold enhancement effects in $(p\bar{p})$-mass spectrum in $J/ψ{\to}γp{\bar p}$ from other possibilities. Experimental checks are expected. An intuitive picture for our results is discussed.

hep-ph↗

arXiv2005

Quantum Horizons

Treating macro-black hole as quantum states, and using Brown-York quaselocal gravitational energy definition and Heisenberg uncertainty principle, we find out the classical horizon with singularity spreads into a quantum horizon in which the space-time is non-commutative and the spread range is determined dynamically. A Quantum Field Theory (QFT) model in curved space with quantum horizon is constructed. By using it, the black hole entropy and the Hawking temperature are calculated successfully. The $ϕ-$field mode number is predicted and our quantum horizon model favors to support the Minimal Super-symmetric Standard Model.

gr-qc↗

arXiv2004

Quantum horizon and thermodynamics of black hole

A semi-classical reasoning leads to the non-commutativity of space and time coordinates near the horizon of static non-extreme black hole, and renders the classical horizon spreading to {\it Quantum Horizon} . In terms of the background metric of the black hole with the {\it Quantum Horizon}, a quantum field theory in curved space without ultraviolet divergency near the horizon is formulated. In this formulism, the black hole thermodynamics is reproduced correctly without both ambiguity and additional hypothesis in the deriving the hole's Hawking radiations and entropies, and a new interesting prediction on the number of radiative field modes $N$ is provided. Specifically, the main results are follows: 1, Hawking radiations rightly emerge as an effect of quantum tunneling through the quantum horizon, and hence the ambiguities due to going across the singularity on the classical horizon were got rid of; 2, 't Hooft's brick wall thickness hypothesis and the boundary condition imposed for the field considered in his brick wall model were got rid of also, and related physics has been interpreted; 3, The present theory is parameter free. So, the theory has power to predict the multiplicity $N$ of radiative field modes according to the requirement of normalization of Hawking-Bekenstein entropy. It has been found that $N\simeq 162$, which is just in good agreement with one in the Minimal Super-symmetric Standard Model. The studies in this paper represent an attempt to reveal some physics near the horizon at Planck scale. This paper serves a brief review on the author's works on this subject.

gr-qc↗