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Mannque Rho

Publications and source records attributed to Mannque Rho.

At least 145 records · Page 8Linked to original sources
arXiv2003

Double Decimation and Sliding Vacua in the Nuclear Many-Body System

We propose that effective field theories for nuclei and nuclear matter comprise of "double decimation": (1) the chiral symmetry decimation (CSD) and (2) Fermi liquid decimation (FLD). The Brown-Rho scaling recently identified as the parametric dependence intrinsic in the "vector manifestation" of hidden local symmetry theory of Harada and Yamawaki results from the first decimation. This scaling governs dynamics down to the scale at which the Fermi surface is formed as a quantum critical phenomenon. The next decimation to the top of the Fermi sea where standard nuclear physics is operative makes up the Fermi liquid decimation. Thus nuclear dynamics is dictated by two fixed points, namely, the vector manifestation fixed point and the Fermi liquid fixed point. It has been a prevalent practice in nuclear physics community to proceed with the second decimation only, assuming density independent masses. We show why most nuclear phenomena can be reproduced by theories using either density-independent, or density-dependent masses, a grand conspiracy of nature that is an aspect that could be tied to the Cheshire-Cat phenomenon in hadron physics. We identify what is left out in the Fermi liquid decimation that does not incorporate the CSD. Experiments such as the dilepton production in relativistic heavy ion reactions, which are specifically designed to observe effects of dropping masses, could exhibit large effects from the reduced masses. However they are compounded with effects that are not directly tied to chiral symmetry. We discuss a recent STAR/RHIC observation where BR scaling can be singled out in a pristine environment.

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arXiv2003

Matching the QCD and Hadron Sectors and Medium Dependent Meson Masses; Hadronization in Relativistic Heavy Ion Collisions

The recent developments on the "vector manifestation" of chiral symmetry by Harada and Yamawaki provide a compelling evidence for, and "refine," the in-medium scaling of hadronic properties in dense/hot matter (call it ``BR scaling") proposed by the authors in 1991. We reinterpret the Harada-Yamawaki result obtained in a Wilsonian renormalization-group approach to hidden local symmetry theory matched to QCD at near the chiral scale in terms of the Nambu-Jona-Lasinio model and predict that the vector meson mass in medium should scale $m_ρ^\star/m_ρ\sim (\la\bar{q}q\ra^\star/\la\bar{q}q\ra)^{1/2}$ from $n=0$ up to $\sim n=n_0$ (where $n_0$ is nuclear matter density) and then go over to the linear scaling $m_ρ^\star/m_ρ\sim \la\bar{q}q\ra^\star/\la\bar{q}q\ra$ up to the chiral transition density $n_c$ at which the mass is to vanish (in the chiral limit) according to the vector manifestation fixed point. In the regime of the linear scaling above $n_0$, the (vector) gauge coupling constant should fall linearly in $\la\bar{q}q\ra^\star$, vanishing at the critical point, with the width of the vector meson becoming steeply narrower. We suggest the in-medium vector meson mass, {\em both} parametric and pole, which goes smoothly to zero with increasing density, to be an order parameter for chiral symmetry restoration. Some issues related to recent RHIC observations are qualitatively discussed in the appendices. Our main conclusion that follows from these considerations is that the movement towards chiral restoration can be reliably described in Nambu-Jona-Lasinio mean field, with constituent quarks as variables, although there is probably density discontinuity following chiral restoration.

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arXiv2003

Effective Degrees of Freedom at Chiral Restoration and the Vector Manifestation in HLS theory

The question as to what the relevant effective degrees of freedom at the chiral phase transition are remains largely unanswered and must be addressed in confronting both terrestrial and space laboratory observations purporting to probe matter under extreme conditions. We address this question in terms of the vector susceptibility χ_V (VSUS in short) and the axial-vector susceptibility χ_A (ASUS in short) at the temperature-induced chiral transition. We consider two possible, albeit simplified, cases that are contrasting, one that is given by the standard chiral theory where only the pions figure in the vicinity of the transition and the other that is described by hidden local symmetry (HLS) theory with the Harada-Yamawaki vector manifestation (VM) where nearly massless vector mesons also enter. We find that while in the standard chiral theory, the pion velocity v_πproportional to the ratio of the space component f_π^s of the pion decay constant over the time component f_π^t tends to zero near chiral restoration with f_π^t\neq 0, in the presence of the vector mesons with vanishing mass, the result is drastically different: HLS with VM {\it predicts} that χ_V automatically equals χ_A in consistency with chiral invariance and that v_π\sim 1$ with $f_π^t\approx f_π^s\to 0 as T\to T_c. These results are obtained in the leading order in power counting but we expect their qualitative features to remain valid more generally in the chiral limit thanks to the VM point.

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arXiv2003

Sliding Vacua in Dense Skyrmion Matter

In continuation of our systematic effort to understand hadronic matter at high density, we study dense skyrmion matter and its chiral phase structure in an effective field theory implemented with the trace anomaly of QCD applicable in the large $N_c$ limit. By incorporating a dilaton field $χ$ associated with broken conformal symmetry of QCD into the simplest form of skyrmion Lagrangian, we simulate the effect of "sliding vacua" influenced by the presence of matter and obtain what could correspond to the ``intrinsic dependence" on the background of the system, i.e., matter density or temperature, that results when a generic chiral effective field theory of strong interactions is matched to QCD at a matching scale near the chiral scale $Λ_χ\sim 4πf_π\sim 1$ GeV. The properties of the Goldstone pions and the dilaton scalar near the chiral phase transition are studied by looking at the pertinent excitations of given quantum numbers on top of a skyrmion matter and their behavior in the vicinity of the phase transition from Goldstone mode to Wigner mode characterized by the changeover from the FCC crystal to the half-skyrmion CC crystal. We recover from the model certain features that are connected to Brown-Rho scaling and that suggest how to give a precise meaning to the latter in the framework of an effective field theory that is matched to QCD .

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arXiv2003

On Effective Degrees of Freedom at Chiral Restoration and the Vector Manifestation

Recent research activities on the chiral structure of hadronic matter near the phase transition predicted by QCD and extensively looked for in terrestrial laboratories as well as in satellite observatories raise the issue of whether we have fully identified the relevant degrees of freedom involved in the transition. In this talk, I would like to discuss a recent novel approach to the issue based on the "vector manifestation" scenario discovered by Harada and Yamawaki in hidden local symmetry theory. For simplicity, I will restrict myself to two extreme scenarios: one that we shall refer to as "standard" in which pions are considered to be the $only$ low-lying degrees of freedom and the other that could be referred to as "non-standard" in which in addition to pions, other degrees of freedom figure in the process. In particular, I shall consider the scenario that arises at one-loop order in chiral perturbation theory with hidden local symmetry Lagrangian consisting of pions as well as nearly massless vector mesons that figure importantly at the ``vector manifestation (VM)" fixed point. It will be shown that if the VM is realized in nature, the chiral phase structure of hadronic matter can be much richer than that in the standard one and the chiral phase transition will be a smooth crossover: Sharp vector and scalar excitations are expected in the vicinity of the critical point. Some indirect indications that lend support to the VM scenario are discussed.

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arXiv2003

A Unified Approach to High Density: Pion Fluctuations in Skyrmion Matter

As the first in a series of systematic work on dense hadronic matter, we study the properties of the pion in dense medium using Skyrme's effective Lagrangian as a unified theory of the hadronic interactions applicable in the large $N_c$ limit. Dense baryonic matter is described as the ground state of a skyrmion matter which appears in two differentiated phases as a function of matter density: i) at high densities as a stable cubic-centered (CC) half-skyrmion crystal; ii) at low densities as an unstable face-centered cubic (FCC) skyrmion crystal. We substitute the latter by a stable inhomogeneous phase of lumps of dense matter, which represents a naive Maxwell construction of the phase transition. This baryonic dense medium serves as a background for the pions whose effective {\em in-medium} Lagrangian we construct by allowing time-dependent quantum fluctuations on the classical dense matter field. We find that the same parameter which describes the phase transition for baryonic matter, the expectation value of the $σ$ field, also describes the phase transition for the dynamics of the {\em in-medium} pion. Thus, the structure of the baryonic ground state $crucially$ determines the behavior of the pion in the medium. As matter density increases, $<σ>$ decreases, a phenomenon which we interpret to signal, in terms of the parameters of the effective pion Lagrangian $f_π^*$ and $m_π^*$, the restoration of chiral symmetry at high density. Our calculation shows also the important role played by the higher powers in the density as it increases and chiral symmetry is being restored. This feature is likely to be generic at high density although our ground state may not be the true ground state.

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arXiv2003

The Vector Manifestation and Effective Degrees of Freedom At Chiral Restoration

The role of effective degrees of freedom on the vector and axial-vector susceptibilities and the pion velocity at chiral restoration is analyzed. We consider two possible scenarios, one in which pions are considered to be the only low-lying degrees of freedom -- that we shall refer to as "standard" -- and the other in which pions, vector mesons and constituent quarks (or quasiquarks in short) are the relevant low-lying degrees of freedom -- that we shall refer to as "vector manifestation (VM)." We show at one-loop order in chiral perturbation theory with hidden local symmetry Lagrangian that while in the standard scenario, the pion velocity vanishes at the chiral transition, it instead approaches unity in the VM scenario. If the VM is realized in nature, the chiral phase structure of hadronic matter can be much richer than that in the standard one and the phase transition will be a smooth crossover: Sharp vector and scalar excitations are expected in the vicinity of the critical point. Some indirect indications that lend support to the VM scenario, and in consequence to BR scaling, are discussed.

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arXiv2002

QCD and Nuclei

I discuss how the fundamental theory of strong interactions given by QCD can be exploited to make accurate predictions for the solar fusion processes involving few-nucleon systems and to provide a novel description of nuclear matter as well as excitations near the chiral phase transition. The tool used is effective field theory combined with the modern technique of renormalization group flow. The notion of "BR scaling" is reinterpreted in terms of the vector manifestation à la Harada and Yamawaki. It is argued that the vector manifestation scenario predicts a QCD phase structure much richer than the standard scenario discussed up to date in the literature.

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arXiv2002

The Cheshire Cat Hadrons Revisited

The notion of Cheshire Cat Principle in hadron structure developed in a 1993 lecture note is revisited by correcting nontrivial errors committed in the lecture and bringing up to date with the recent developments on the "vector manifestation" of chiral symmetry a la Harada-Yamawaki.

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arXiv2002

Lectures on Effective Field Theories for Nuclei, Nuclear Matter and Dense Matter

This note is based on four lectures that I gave at the 10th Taiwan Nuclear Spring School held at Hualien, Taiwan in January 2002. It aims to correlate the old notion of Cheshire Cat Principle developed for elementary baryons to the modern notion of quark-baryon and gluon-meson "continuities" or "dualities" in dilute and dense many-body systems and predict what would happen to mesons when squeezed by nuclear matter to high density as possibly realized in compact stars. Using color-flavor locking in QCD, the vector mesons observed at low density can be described as the Higgsed gluons dressed by cloud of collective modes, i.e., pions just as they are in superdense matter, thus showing the equivalence between hidden $flavor$ gauge symmetry and explicit $color$ gauge symmetry. Instead of going into details of well-established facts, I focus on a variety of novel ideas -- some solid and some less -- that could be confirmed or ruled out in the near future.

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arXiv2002

Vector Manifestation and Fate of Vector Mesons in Dense Matter

We describe in-medium properties of hadrons in dense matter near chiral restoration using a Wilsonian matching to QCD of an effective field theory with hidden local symmetry at the chiral cutoff $Λ$. We find that chiral symmetry is restored in vector manifestation à la Harada and Yamawaki at a critical matter density $n_c$. We express the critical density in terms of QCD correlators in dense matter at the matching scale. In a manner completely analogous to what happens at the critical $N_f^c$ and at the critical temperature $T^c$, the vector meson mass is found to vanish (in the chiral limit) at chiral restoration. This result provides a support for Brown-Rho scaling predicted a decade ago.

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arXiv2001

The Solar $hep$ Processes in Effective Field Theory

By combining effective field theory with the standard nuclear physics approach (SNPA) we obtain a high-precision estimate of the $S$ factor for the solar $hep$ process. The accurate wave functions available in SNPA are used to evaluate the nuclear matrix elements for the transition operators that result from chiral perturbation theory (ChPT). All the contributions up to \nlo3 in ChPT are included. The resulting parameter-free, error-controlled prediction is: $S(hep)=(8.6 \pm 1.3)\times 10^{-20}$ keV-b.

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arXiv2001

Kaon Condensation and Enforced Charge Neutrality of the Color-Flavor Locked Phase

We investigate the influence of charged kaon condensation in hadronic sector on the formation of the electron-free charge neutral quark matter of equipartition of three light flavors, i.e., a phenomenon called ``enforced electrical neutrality" of the color-flavor locked (CFL) phase. We employ the chiral quark model which is assumed to be applicable, "bottom-up," toward chiral restoration while accessible to kaon condensation in the hadronic sector. Approaching "bottom-up" the high density regime is more appropriate in addressing the properties of compact stars than approaching "top-down" from asymptotic QCD. It turns out that the presence of hadronic kaon condensation makes the electron-free charge-neutral CFL phase energetically more favorable with a relatively small color-superconducting gap $Δ_0\sim 20$ MeV compared to $Δ_0\sim 70$ MeV required in the absence of such kaon condensation.

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arXiv2001

On the Manifestation of Chiral Symmetry in Nuclei and Dense Nuclear Matter

This article reviews our view on how chiral symmetry, its pattern of breaking and restoration under extreme conditions manifest themselves in the nucleon, nuclei, nuclear matter and dense hadronic matter. Topics treated are nucleon structure in terms of chiral symmetry, "first-principle" (QCD) calculations of the properties of finite nuclei effectuated by embedding the ``standard nuclear physics approach" into the framework of effective field theories of nuclei with predictions for certain astrophysical processes, a reinterpretation of the Brown-Rho (BR) scaling that implements chiral symmetry property of baryon-rich medium à la "vector manifestation" of hidden local symmetry, evidences for BR scaling in nuclear processes at normal nuclear matter density and at higher density, the notion of "broadband equilibration" in heavy-ion processes, and the role of strangeness in the formation of compact stars and their collapse into black-holes. We revisit the "Cheshire-Cat phenomenon" recently revived in the form of "quark-hadron continuity" in mapping low-density structure of hadrons to high-density structure of quarks and gluons and suggest how color-flavor locking in terms of QCD variables and hidden local symmetry in terms of hadronic variables may be connected and how BR scaling could fit into this "continuity" scheme.

hep-ph↗
arXiv2001

The Fate of Hadron Masses in Dense Matter: Hidden Local Symmetry and Color Flavor Locking

The notion that hadron masses scale according to the scaling of the quark condensate in hadronic matter, partly supported by a number of observations in finite nuclei, can be interpreted in terms of Harada-Yamawaki's ``vector manifestation" (VM) of chiral symmetry. In this scenario, near chiral restoration, the vector meson masses drop to zero {\it in the chiral limit} with vanishing widths. This scenario appears to differ from the standard linear sigma model scenario. We exploit a link between the VM and color-flavor locking inferred by us from lattice data on quark number susceptibility (QNS) measured as a function of temperature to suggest that local flavor symmetry gets mapped to color gauge symmetry at the chiral phase transition.

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arXiv2000

Strangeness Equilibration at GSI Energies

We develop the notion of "broad-band equilibration" in heavy-ion processes involving dense medium. Given density-dependent \Km-masses we show that the equilibration at GSI energies claimed to hold in previous treatments down to $\sim ρ_0/4$, can be replaced by a broad-band equilibration in which the \Km-meson and hyperons are produced in an essentially constant ratio independent of density. There are experimental indications that this also holds for AGS energies. We then proceed to argue that {\it both} $K^+$ and $K^-$ must get lighter in dense medium at some density $ρ>ρ_0$ due to the decoupling of the vector mesons. As a consequence, kaon condensation in compact stars could take place {\it before} chiral restoration since the sum of bare quark masses in the kaon should lie below $μ_e$. Another consequence of the decoupling vector interactions is that the quasi-particle picture involving (quasi)quarks, presumably ineffective at low densities, becomes more appropriate at higher densities as chiral restoration is approached.

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arXiv2000

Neutrino Interactions In Color-Flavor-Locked Dense Matter

At high density, diquarks could condense in the vacuum with the QCD color spontaneously broken. Based on the observation that the symmetry breaking pattern involved in this phenomenon is essentially the same as that of the Pati-Salam model with broken electroweak--color SU(3) group, we determine the relevant electroweak interactions in the color-flavor locked (CFL) phase in high density QCD. We briefly comment on the possible implications on the cooling of neutron stars.

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