arXiv subjects

Mannque Rho

Publications and source records attributed to Mannque Rho.

At least 37 records · Page 2Linked to original sources

arXiv2021

Topology change, emergent symmetries and compact star matter

Topology effects have being extensively studied and confirmed in strongly correlated condensed matter physics. In the large color number limit of QCD, baryons can be regarded as topological objects -- skyrmions -- and the baryonic matter can be regarded as a skyrmion matter. We review in this paper the generalized effective field theory for dense compact-star matter constructed with the robust inputs obtained from the skyrmion approach to dense nuclear matter, relying to possible ``emergent" scale and local flavor symmetries at high density. All nuclear matter properties from the saturation density $n_0$ up to several times $n_0$ can be fairly well described. A uniquely novel -- and unorthdox -- feature of this theory is the precocious appearance of the pseudo-conformal sound velocity $v^2_{s}/c^2 \approx 1/3$, with the non-vanishing trace of the energy momentum tensor of the system. The topology change encoded in the density scaling of low energy constants is interpreted as the quark-hadron continuity in the sense of Cheshire Cat Principle (CCP) at density $\gsim 2n_0$ in accessing massive compact stars. We confront the approach with the data from GW170817 and GW190425.

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arXiv2021

Fractionalized Quasiparticles in Dense Baryonic Matter

I discuss a novel scenario on how baryonic matter could turn into a Fermi liquid of fractionalized baryons driven by high density inside compact stars. It involves the "hidden" local vector bosons $ρ$ and $ω$ together with the "hidden" scale symmetry dilaton $χ$, both taken to be "dual" to the quarks and gluons of QCD in the sense of quark $\leftrightarrow$ hadron duality and offers a possibility, exploiting the "Cheshire Cat Principle", to unify the "dichotomy" of baryons described in terms of skyrmions and fractional quantum Hall (FQH) droplets {\it and} to explore how the baryonic matter could behave as density goes way beyond the normal nuclear matter density to the density regime where "deconfined" quarks are presumed to figure. The question is raised as to whether the fractionalized characteristics of the "stuff" -- whatever they are -- can be "probed" in the dense star core of compact stars.

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arXiv2021

Manifestation of Hidden Symmetries in Baryonic Matter: From Finite Nuclei to Neutron Stars

The hadron-quark/gluon duality formulated in terms of a topology change at a density $n\gsim 2n_0$ $n_0\simeq 0.16$fm$^{-3}$ is found to describe the core of massive compact stars in terms of quasiparticles of fractional baryon charges, behaving neither like pure baryons nor like deconfined quarks. This can be considered as the Cheshire-Cat mechanism~\cite{CC} for the hadron-quark continuity arrived at bottom-up from skyrmions that is equivalent to the "MIT-bag"-to-skyrmion continuity arrived at top-down from quarks/gluons. Hidden symmetries, both local gauge and pseudo-conformal (or broken scale), emerge and give rise both to the long-standing "effective $g_A^\ast\approx 1$" in nuclear Gamow-Teller transitions at $\lsim n_0$ and to the pseudo-conformal sound velocity $v_{pcs}^2/c^2\approx 1/3$ at $\gsim 3n_0$. It is suggested that what has been referred to, since a long time, as "quenched $g_A$" in light nuclei reflects what leads to the dilaton-limit $g_A^{\rm DL}=1$ at near the (putative) infrared fixed point of scale invariance. These properties are confronted with the recent observations in Gamow-Teller transitions and in astrophysical observations.

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arXiv2021

The sound speed and core of massive compact stars: A manifestation of hadron-quark duality

When baryon-quark continuity is formulated in terms of a topology change without invoking "explicit " QCD degrees of freedom at a density higher than twice the nuclear matter density $n_0$ the core of massive compact stars can be described in terms of fractionally charged particles, behaving neither like pure baryons nor deconfined quarks. Hidden symmetries, both local gauge and pseudo-conformal (or broken scale), lead to the pseudo-conformal (PC) sound velocity $v_{pcs}^2/c^2\approx 1/3$ at $\gsim 3n_0$ in compact stars. We argue these symmetries are "emergent" from strong nuclear correlations and conjecture that they reflect hidden symmetries in QCD proper exposed by nuclear correlations. We establish a possible link between the quenching of $g_A$ in superallowed Gamow-Teller transitions in nuclei and the precocious onset at $n\gsim 3n_0$ of the PC sound velocity predicted at the dilaton limit fixed point. We propose that bringing in explicit quark degrees of freedom as is done in terms of the "quarkyonic" and other hybrid hadron-quark structure and our topology-change strategy represent the "hadron-quark duality" formulated in terms of the Cheshire-Cat mechanism~\cite{CC} for the smooth cross-over between hadrons and quarks. Confrontation with currently available experimental observations is discussed to support this notion.

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arXiv2021

The "Folk Theorem" on Effective Field Theory: A Case for Nuclear Physics

Although largely unrecognized, Gerry Brown had played a seminal and prescient role for the development of the currently heralded "first-principles approach" to nuclear dynamics known as "nuclear effective field theory" ($n$EFT for short). I give a brief account in what way he entered -- together with his Korean colleagues -- at the earliest stage of its development and what he left behind for the future in paving the road to go {\it way beyond} the standard $n$EFT. I do this in the context of Gerry's original conceptual ideas conceived after the "dilepton fiasco" that indicate a surprising new role of hidden local and scale symmetries in nuclear physics.

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arXiv2021

Mapping topology to nuclear dilaton-HLS effective field theory for dense baryonic matter

We describe the on-going effort to formulate the baryon-quark continuity in terms of a topology change in the equation of state (EoS) of dense baryonic matter in analogy to -- and inspired by -- the mapping of the characteristics of Chern-Simon topological field theory to Kohn-Sham density functional theory in the fractional quantized Hall effect (FQHE). This is done by translating the density-dependent characteristics of the skyrmion-half-skyrmion transition formulated in the presence of hidden local symmetry and (hidden) scale symmetry to the density-dependent parameters of a renormalization-group approach to Fermi-liquid fixed point theory. Predictions made in finite nuclei and infinite compact-star matter are presented.

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arXiv2020

What's in the core of massive neutron stars?

When hadron-quark continuity is formulated in terms of a topology change at a density higher than twice the nuclear matter densiy $n_0$ the core of massive compact stars can be described in terms of quasiparticles of fractional baryon charges, behaving neither like pure baryons nor deconfined quarks. Hidden symmetries, both local gauge and pseudo-conformal (or broken scale), emerge and give rise to the long-standing quenched $g_A$ in nuclear Gamow-Teller transitions at $\sim n_0$ and to the pseudo-conformal sound velocity $v_{pcs}^2/c^2\approx 1/3$ at $\gsim 3n_0$. These properties are confronted with the recent observations in superallowed Gamow-Teller transitions and in astrophysical observations.

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arXiv2020

The Quenched ${g_A}$ in Nuclei and Emergent Scale Symmetry in Baryonic Matter

A recent RIKEN experiment on the quenched $g_A$ in the superallowed Gamow-Telller transition from $^{100}$Sn indicates a role of scale anomaly encoded in the anomalous dimension $β^\prime$ of the gluonic stress tensor ${\rm Tr \ G}_{μν}^2$. This observation provides a support to the notion of hidden scale symmetry emerging by strong nuclear correlations with an IR fixed point realized -- in the chiral limit -- in the Nambu-Goldstone mode. We suggest there is an analogy in the way scale symmetry manifests in nuclear medium to the continuity from the unitarity limit at low density (in light nuclei) to the dilaton limit at high density (in compact stars). In between the limits, say, at normal nuclear matter density, the symmetry is not visible, hence hidden.

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arXiv2020

Towards the Hadron-Quark Continuity Via a Topology Change in Compact Stars

We construct a generalized EFT approach to dense compact-star matter that exploits the CCP for hadron-quark continuity at high density, hidden topology and hidden symmetries of QCD. No Landau-Ginzburg-Wilsonian-type phase transition is involved. The microscopic DoF of QCD possibly intervening at high baryonic density are traded in for fractionalized topological objects. Essential in the description are symmetries invisible in QCD in the matter-free vacuum: Scale symmetry, flavor local symmetry and parity-doubling. The partial emergence of scale symmetry is signaled by a dilatonic scalar in a "pseudo-conformal" structure. Flavor gauge symmetry manifests with the $ρ$ meson mass going toward a Wilsonian RGFP identified with the VMFP at which the gauge boson mass goes to zero. Parity doubling is to take place as the quasi-nucleon mass converges to the chiral invariant $m_0$. The theory accounts satisfactorily for all known properties of normal nuclear matter and makes certain predictions that are drastically different from what's available in the literature. In particular, it provides a topological mechanism, argued to be robust, for the cross-over from soft-to-hard EoS that predicts the star properties in overall agreement with the presently available data, including the maximum star mass $M_{max}\sim 2.3 M_\odot$ and the recent LIGO/Virgo GW data. What is most glaringly different from all other approaches known, however, is the prediction for the rapid convergence to a sound velocity of star $v_s^2\approx 1/3$ at a density $n\gsim 3 n_0$, far from the asymptotic density $\gsim 50n_0$ expected in pQCD. We interpret this to signal the onset of albeit approximate conformal symmetry in dense compact-star matter. The model developed here could bring out a new paradigm in nuclear/hadron physics, exploiting ideas in condensed matter physics, nuclear and particle physics and astrophysics.

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arXiv2019

Sound velocity and tidal deformability in compact stars

The sound velocity $v_s$ and dimensionless tidal deformability $Λ$ are analyzed using the pseudo-conformal model we developed before. In contrast to the conclusion obtained in the previous works in the literature, our model with the upper bound of the sound velocity $v_s = 1/\sqrt{3}$, the so-called conformal sound velocity, set in at a { density relevant to compact stars} $\gsim 2 n_0$ where $n_0$ is the normal nuclear matter density, can accommodate {\it all} presently established nuclear matter and compact-star properties including the maximum star-mass constraint $ \simeq 2.3 M_\odot$. This observation is associated with a possible emergence of pseudoconformal structure in compact star matter---in which the trace of energy-momentum tensor is a nearly density-independent nonzero constant---brought in by a topology change at $2.0 \lesssim n_{1/2}/n_0 \lesssim 4.0$ commensurate with a possible change of degrees of freedom from hadrons.

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arXiv2019

Resolving the Quenched ${g_A}$ Puzzle in Nuclei and Nuclear Matter

The long-standing puzzle of the quenched $g_A$ in nuclei -- and in dense matter -- is shown to have a simple resolution in a scale-symmetric HLS chiral Lagrangian at the Fermi-liquid fixed point. This resolution exposes scale-chiral symmetry, hidden in QCD in the vacuum, emerging in nuclear matter from low density to high compact-star density. It has important implications on "first principles" approaches to nuclear physics, such as the role of multi-body exchange currents in Gamow-Teller matrix elements in nuclei and in neutrinoless double $β$ decays for going Beyond the Standard Model.

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arXiv2019

A Solution to the Quenched ${g_A}$ Problem in Nuclei and Dense Baryonic Matter

When scale symmetry is combined with chiral symmetry in a scale-chiral Lagrangian, it can be shown in Fermi-liquid fixed point theory that $g_A^{\rm eff}\approx 1$ in finite nuclei {\it as well as} in dense baryonic matter. This is suggested as a signal for emergence of hidden symmetries of QCD in baryonic matter from low to very high density. This calculation throws doubt on the "first principles" explanation of the quenching of $g_A$ in nuclei with two-body meson-exchange currents. It also has relevance to Gamow-Teller matrix elements in neutrinoless double $β$ decay.

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arXiv2019

Baryon as a Quantum Hall Droplet and the Cheshire Cat Principle

We show that the recent proposal to describe the $N_f=1$ baryon in the large number of color limit as a quantum Hall droplet, can be understood as a chiral bag in a 1+2 dimensional strip using the Cheshire cat principle. For a small bag radius, the bag reduces to a vortex line which is the smile of the cat with flowing gapless quarks all spinning in the same direction. The disc enclosed by the smile is described by a topological field theory due to the Callan-Harvey anomaly out-flow. The chiral bag carries naturally unit baryon number and spin $\frac 12 N_c$. The generalization to arbitrary $N_f$ is discussed.

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arXiv2019

A pseudo-conformal structure in dense baryonic matter

We clarify and extend further the idea developed in \cite{PKLMR,MLPR} that baryonic matter at high density has an emergent "pseudo-conformal symmetry." It is argued that as baryonic density exceeds $n \simeq n_{1/2} \gtrsim 2n_0$, a topology change mimicking the baryon-quark continuity takes place at $n_{1/2}$. In terms of skyrmions, this corresponds to the transition from skyrmions to half-skyrmions and impacts on the equation of state of dense baryonic matter. The emergence in medium at $n_{1/2}$ of parity-doublet symmetry -- which is invisible in QCD in matter-free vacuum -- plays the crucial role. The consequence of the topology change is that massive compact stars carry the "pseudo-conformal sound velocity" $v_s^2/c^2\approx 1/3$ at $n\gsim n_{1/2}$ signaling a precursor to precocious emergence of scale symmetry as well as {a} local symmetry hidden in QCD in the matter-free vacuum. A highly significant prediction of this work is that the topology change density from normal matter to half-skyrmion matter, up-to-date inaccessible either by QCD proper or by terrestrial experiments, could possibly be pinned down within the range $2 < n_{1/2}/n_0 < 4$, commensurate with the range expected for a continuous hadrons-to-quarks/gluons transition.

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arXiv2019

Topology change and nuclear symmetry energy in compact-star matter

We show that the cusp-like structure in the nuclear symmetry energy, a consequence of topology change, visible in the skyrmion lattice description of dense matter is extremely robust. It is present in the Skyrme model -- with the pion field only -- and is left unscathed by massive degrees of freedom such as the vector mesons $ρ$ and $ω$ and also the scalar meson introduced as a dilaton. It leads to the emergence of parity-doubling at the skyrmion-half-skyrmion transition and impacts on the nuclear symmetry energy "wilderness" landscape, weeding out roughly half of the wilderness. It is shown that a pseudo-conformal sound velocity arises at a precocious density at which the cusp is formed. It is suggested that the topology change, being robust, could impact on the tidal deformability observed in gravity waves

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arXiv2018

The Non-Quenching of $g_A$ in Nuclei and Emergent Scale Symmetry in Dense Baryonic Matter

How the axial coupling constant $g_A$ in nuclear Gamow-Teller transitions described in shell model gets "quenched" to a universal constant close to 1 can be explained by nuclear correlations in Fermi-liquid fixed point theory using a scale-symmetric chiral Lagrangian supplemented with hidden local symmetric vector mesons. Contrary to what one might naively suspect -- and has been discussed in some circles, there is no fundamental quenching at nuclear matter density due to QCD condensates. When the density of many-body systems treated with the same Lagrangian increases beyond the density $n=n_{1/2}\gsim 2n_0$ (where $n_0$ is the normal nuclear matter density) at which skyrmions representing baryons fractionize to half-skyrmions, with the $ρ$ meson driven toward the vector manifestation fixed point and a scalar meson $σ$ driven to the dilaton-limit fixed point with the nucleons parity-doubled, the dense matter supports the "pseudo-conformal" sound velocity for $n\gsim n_{1/2}$ while the trace of the energy momentum tensor remains non-vanishing. A plausible interpretation is that this signals the emergence of scale symmetry not explicitly present or hidden in QCD in the vacuum. The fundamental constant $g_A$, unaffected by QCD condensates for $n< n_{1/2}$, does go to 1 as the dilaton-limit fixed point is approached before arriving at chiral restoration, but it is not directly related to the "quenched $g_A$" in nuclei which can be explained as a Fermi-liquid fixed point quantity. The mechanism that produces a precocious pseudo-conformal sound velocity is expected to impact on the tidal deformability $Λ$ in gravity waves from coalescing neutron stars.

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arXiv2018

A pseudo-conformal equation of state in compact-star matter from topology change and hidden symmetries of QCD

We construct a new effective field theory approach to the equation of state (EoS), dubbed pseudo-confomal model "PCM," for nuclear and compact star matter entirely in terms of effective hadron degrees of freedom. The possible transition at $n\sim (2-4) n_0$ (where $n_0$ is the normal nuclear matter density) from hadron degrees of freedom to strongly-coupled quark degrees of freedom, giving rise to a soft-to-hard changeover in the EoS that can accommodate the massive stars observed, is effectuated by the topology change at $n_{1/2}\gsim 2n_0$ from skyrmions to half-skyrmions without involving local order-parameter fields. The mechanism exploits possible emergence of hidden scale and local symmetries of QCD at high density, leading to a precocious "pseudo-conformal" sound velocity $v_s^2=1/3$ (in unit of $c=1$) for $n\gsim 3n_0$. The resulting prediction signals a drastic departure from standard nuclear many-body theory in the density regime involved in the massive stars. We suggest that the tidal deformability implemented in gravitational waves coming from coalescing neutron stars in LIGO/Virgo-type observations could pin down the location of the topology change density $n_{1/2}$.

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arXiv2018

Going from Asymmetric Nuclei to Neutron Stars to Tidal Polarizability in Gravitational Waves

Among the five-year government-funded World Class University Projects in Korea, the category-3 program approved at Hanyang University in Seoul led to an exploratory effort to go from neutron-rich nuclei to dense matter in neutron stars. The principal results in what transpired in the effort -- and what followed afterwards -- are described with the focus on the possibly important, hitherto unexplored, role played in nuclear dynamics of topology and hidden symmetries of QCD. The potential link to the proton mass problem is pointed out.

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