Yong-Liang Ma

Dense baryonic matter in the hidden local symmetry approach: Half-skyrmions and nucleon mass

Hadron properties in dense medium are treated in a unified way in a skyrmion model constructed with an effective Lagrangian, in which the rho and omega vector mesons are introduced as hidden gauge bosons, valid up to O(p^4) terms in chiral expansion including the homogeneous Wess-Zumino terms. All the low energy constants - apart from f_pi and m_rho - are fixed by the master formula derived from the relation between 5-D hQCD and 4-D HLS. This allows one to pin down the density n_1/2 at which the skyrmions in medium fractionize into half-skyrmions, bringing in a drastic change in the EoS of dense matter. We find that the U(1) field that figures in the CS term in the hQCD action or equivalently the omega field in the hWZ term in the dimensionally reduced HLS action plays a crucial role in the half-skyrmion phase. The importance of the omega degree of freedom may be connected to what happens in the instanton structure of elementary baryon noticed in hQCD. The most striking and intriguing in what is found in the model is that f_pi that smoothly drops with increasing density in the skyrmion phase stops decreasing at n_1/2 and remains nearly constant in the half-skyrmion phase. In accordance with the large N_c consideration, the baryon mass also stays non-scaling in the half-skyrmion phase. This feature which is reminiscent of the parity-doublet baryon model with a chirally invariant mass m_0 is supported by the nuclear EFT with the parameters of the Lagrangian scaling modified at the skyrmion-half-skyrmion phase transition. It also matches with one-loop RG analysis based on HLS. A link between a non-vanishing m_0 and the origin of nucleon mass distinctive from dynamically generated mass is suggested. We briefly discuss the possible consequences of the topology change found in this paper on the forthcoming experiments at the RIB machines under construction.

Mass degeneracy of heavy-light mesons with chiral partner structure in the half-Skyrmion phase

We explore the mass splitting of heavy-light mesons with chiral partner structure in nuclear matter. In our calculation, we employed the heavy hadron chiral perturbation theory with chiral partner structure, and the nuclear matter is constructed by putting Skyrmions from the standard Skyrme model onto the face-centered cubic crystal and regarding the Skyrmion matter as nuclear matter. We find that, although the masses of heavy-light mesons with chiral partner structure are split in matter-free space and the Skyrmion phase, they are degenerated in the half-Skyrmion phase in which the chiral symmetry is restored globally. This observation suggests that the magnitude of the mass splitting of heavy-light mesons with chiral partner structure can be used as a probe of the phase structure of nuclear matter.

Skyrmions with vector mesons in the hidden local symmetry approach

(hWZ) terms. We write a general “master formula” that allows us to determine the parameters of the HLS Lagrangian from a class of holographic QCD models valid at large Nc and � (’t Hooft constant) limit by integrating out the infinite towers of vector and axial-vector mesons other than the lowest � and ! mesons. Within this approach we find that the physical properties of the Skyrmion as the solitonic description of baryons are independent of the HLS parameter a. Therefore the only parameters of the model are the pion decay constant and the vector meson mass. Once determined in the meson sector, we have a totally parameter-free theory that allows us to study unequivocally the role of light vector mesons in the Skyrmion structure. We find, as suggested by Sutcliffe, that

Inhomogeneous quark condensate in compressed Skyrmion matter

The inhomogeneous quark condensate, responsible for dynamical chiral symmetry breaking in cold nuclear matter, is studied by putting skyrmions onto the face-centered cubic crystal and treating the skyrmion matter as nuclear matter. By varying the crystal size, we explore the effect of density on the local structure of the quark-antiquark condensate. By endowing the light vector mesons

Chiral-scale effective theory including a dilatonic meson

\rho

Skyrmions, half-skyrmions and nucleon mass in dense baryonic matter

and

Effect of sigma meson on theD1(2430)→Dππdecay

\omega

Effects of scalar mesons in a Skyrme model with hidden local symmetry

with hidden local symmetry and incorporating a scalar meson as a dilaton of spontaneously broken scale symmetry, we uncover the intricate interplay of heavy mesons in the local structure of the quark condensate in dense baryonic matter described in terms of skyrmion crystal. It is found that the inhomogeneous quark density persists to as high a density as

DandD*meson mixing in spin-isospin correlated cold nuclear matter

\sim 4

Strong and radiative decays of X(3872) as a hadronic molecule with a negative parity

times nuclear matter density. The difference between the result from the present approach and that from the chiral density wave ansatz is also discussed.