Meson Field Theory Research Articles

COMPARATIVE STUDY ON CHARGED AND NEUTRAL PION-NUCLEON COUPLING CONSTANTS USING YUKAWA POTENTIAL MODEL

The meson field theory based on the Yukawa model for nuclear forces is estimated using a simple relationship between the charged and neutral pion- nucleon coupling constant. This signifies that the charged coupling constant is larger compared to the value obtains for neutral pions. Therefore since np interaction is stronger than the pp interaction, we look at the value obtained for charged pion – nucleon constant which gives good agreement with one of the recent experimental values, and then the splitting between the charged and neutral pion – nucleon coupling constants is practically the same as that between charged and neutral pion mass. In this case, the mass difference between the charged and neutral pion is also calculated to assess the amount of charge dependence of the Neutron – Neutron scattering length

Chiral theory of ρ -meson gravitational form factors

The low-energy chiral effective field theory of vector mesons and Goldstone bosons in external gravitational field is considered. The energy-momentum tensor is obtained and the gravitational form factors of the $\rho$-meson are calculated up to next-to-leading order in the chiral expansion. This amounts to considering tree-level and one-loop order diagrams. The chiral expansion of the form factors at zero momentum transfer as well as of the slope parameters is worked out. Also, the long-range behaviour of the energy and internal force distributions is obtained and analysed.

The emergence of electroweak Skyrmions through Higgs bosons

Skyrmions are extended field configurations, initially proposed to describe baryons as topological solitons in an effective field theory of mesons. We investigate and confirm the existence of skyrmions within the electroweak sector of the Standard Model and study their properties. We find that the interplay of the electroweak sector with a dynamical Higgs field and the Skyrme term leads to a non-trivial vacuum structure with the skyrmion and perturbative vacuum sectors separated by a finite energy barrier. We identify dimension-8 operators that stabilise the electroweak skyrmion as a spatially localised soliton field configuration with finite size. Such operators are induced generically by a wide class of UV models. To calculate the skyrmion energy and radius we use a neural network method. Electroweak skyrmions are non-topological solitons but are exponentially long lived, and we find that the electroweak skyrmion is a viable dark matter candidate. While the skyrmion production cross section at collider experiments is suppressed, measuring the size of the Skyrme term in multi-Higgs-production processes at high-energy colliders is a promising avenue to probe the existence of electroweak skyrmions.

Galilean-invariant effective field theory for the X(3872) at next-to-leading order

XEFT is a low-energy effective field theory for charm mesons and pions that provides a systematically improvable description of the $X(3872)$ resonance. To simplify calculations beyond leading order, we introduce a new formulation of XEFT with a dynamical field for a pair of charm mesons in the resonant channel. We simplify the renormalization of XEFT by introducing a new renormalization scheme that involves the subtraction of amplitudes at the complex $D^{*0} \bar D^0$ threshold. The new formulation and the new renormalization scheme are illustrated by calculating the complex pole energy of $X$ and the $D^{*0} \bar D^0$ scattering amplitude to next-to-leading order using Galilean-invariant XEFT.

Chiral symmetries in nuclear physics

In this report the theoretical concepts of a chirally symmetric meson field theory are reviewed and an overview of the most relevant applications in nuclear physics is given. This includes a unified description of the vacuum properties of hadrons, finite nuclei and hot, dense and strange nuclear matter in an extended chiral SU(3)_L x SU(3)_R σ-ω model.

Sensitivity of the excitation functions of collective flow to relativistic scalar and vector meson interactions in the relativistic quantum molecular dynamics model RQMD.RMF

Relativistic quantum molecular dynamics with scalar and vector interactions based on the relativistic mean meson field theory, RQMD.RMF, is developed.It is implemented into the microscopic transport code JAM.The sensitivity of the directed and of the elliptic proton flow in high energy heavy-ion collisions on the stiffness of the RMF equation of state (EoS) is examined. These new calculations are compared to experimental data at mid-central Au + Au collisions in the beam energy range $2.5 < \sqrt{s_{NN}} < 20$ GeV. This new RQMD model with the relativistic mean field scalar and vector meson interactions does describe consistently, with one RMF parameter set,the beam energy dependence of both the directed flow and the elliptic flow,from SIS18 to AGS and RHIC BES-II energies, $\sqrt{s_{NN}}< 10$ GeV.There are different sensitivities of these different kinds of flow to the EoS: elliptic flow is most sensitive to the nuclear incompressibility constant,at the moderate beam energies $\sqrt{s_{NN}}<3$ GeV,whereas the directed flow is most sensitive to the effective baryon mass at saturation density at $3< \sqrt{s_{NN}}<5 $ GeV. Matters abruptly change in the next higher energy range,$\sqrt{s_{NN}}\gtrsim 10-20$ GeV:the directed flow data show a double change of sign of the slope of $v_1$, inverting twice in this energy range,in sudden contradiction to the RQMD.RMF calculation for a monotonous, stiff EoS. This surprising oscillating behavior,a double change of sign of the $v_1$ slope, points to the appearance of a hitherto unknown first-order phase transition in excited QCD matter at high baryon densities in mid-central Au + Au collisions.

Production of X(3872) accompanied by a pion in B meson decay

If the $X(3872)$ is a weakly bound charm-meson molecule, it can be produced by the creation of $D^{*0} \bar{D}^0$ or $D^{0} \bar{D}^{*0}$ at short distances followed by the formation of the bound state from the charm-meson pairs. It can also be produced by the creation of $D^{*} \bar{D}^*$ at short distances followed by the rescattering of the charm mesons into $X \pi$. We use results of a previous isospin analysis of $B$ meson decays into $K D^{(*)} \bar D^{(*)}$ to estimate the short-distance amplitudes for creating $D^* \bar D^*$. We use an effective field theory for charm mesons and pions called XEFT to calculate the amplitudes for rescattering of $D^{*} \bar{D}^*$ into $X \pi$ with small relative momentum. The $X\pi$ invariant mass distribution is predicted to have a narrow peak near the $D^{*} \bar{D}^*$ threshold from a charm-meson triangle singularity. We estimate the branching fractions into the peak from the triangle singularity for the decays $B^0 \to K^+ X \pi^-$ and $B^+ \to K^0 X \pi^+$.

Kerson Huang

Kerson Huang, a professor emeritus at MIT who was best known for his contributions to statistical physics, died of cancer on 1 September 2016 in Danvers, Massachusetts. Kerson Huang NANYANG TECHNOLOGICAL UNIVERSITYPPT|High resolutionHuang was born on 15 March 1928 in Nanning, Guangxi Province, China. After the Japanese invaded in 1937, he and his family moved to Manila, the Philippines. Following the end of World War II, he went to the US, where he obtained his BS in 1950 and his PhD in 1953, both in physics and both from MIT. His earliest research was on the zitterbewegung (“trembling motion”) of the Dirac electron. Victor Weisskopf was his thesis adviser, but Huang worked more closely with Sidney Drell on meson field theory. He learned the pseudopotential method from Weisskopf and applied it to the study of the quantum mechanical problem of hard spheres.In the fall of 1955, Huang went to the Institute for Advanced Study in Princeton, New Jersey, for his postdoc and introduced to Chen Ning Yang the pseudopotential method. Together with Tsung-Dao Lee, they collaborated on the problem of dilute hard-sphere bosons and demonstrated the superfluidity of dilute Bose gases due to Bose–Einstein condensation. Huang presented that work at the institute to an audience that included Eugene Wigner, Freeman Dyson, J. Robert Oppenheimer, and Wolfgang Pauli. Pauli slept during the seminar and only woke up to comment that he did not like the pseudopotential because it is not Hermitian. However, he said later that Huang’s work was nicht dumm (“not dumb”). Fifty years later the work was confirmed by experiments on Bose– Einstein condensation in alkali gases.Huang returned to MIT in 1957 as an assistant professor and continued his studies in both many-body problems and particle physics. Ranging from high-energy to low-temperature physics, his research covered numerous topics, including pion decay, muon capture, high-energy scattering, bootstrap solutions, and imperfect Fermi and Bose gases. MIT mathematician John Nash frequently engaged Huang in discussions about the fundamentals and philosophy of quantum mechanics.In the 1960s and 1970s, Huang worked on the dual resonance model. During a weekend vacation at his log cabin in New Hampshire in 1970 with colleague Steven Weinberg, Huang mentioned the concept of ultimate temperature, above which adding energy to a system only produces particles instead of raising the system’s temperature. Weinberg immediately realized its importance in the early universe. They spent the weekend doing calculations, and soon after they published an influential article on the subject.Huang made many substantial contributions during the development of the standard model in particle physics. By considering the possibility of asymptotic freedom in scalar field theories, he challenged the common perception that only non-abelian gauge theories are asymptotically free. He and his student Kenneth Halpern showed that some scalar theories could become asymptotically free provided that what’s now known as the Halpern–Huang potential is used to describe the interaction.Huang also devoted great effort to physics education. He wrote eight physics books, including Statistical Mechanics (Wiley, 1963; 2nd edition, 1987), Introduction to Statistical Physics (Taylor & Francis, 2001), and Quantum Field Theory: From Operators to Path Integrals (Wiley, 1998; 2nd edition, 2010), which continue to be widely used as textbooks and references.Huang became a professor emeritus in 1999 and remained with the Center for Theoretical Physics at MIT until 2005. He then became a visiting professor at Tsinghua University in China and at Nanyang Technological University in Singapore. His interests shifted to biophysics and quantum cosmology. Huang proposed a conditioned self-avoiding walk model and wrote a MATLAB program to study the problem of protein folding. In quantum cosmology, he proposed a superfluid-universe scenario for inflation, matter creation, dark matter, and dark energy. He also suggested using a vortex boundary layer, now known as the Kerson layer, to solve the matching problem in the gravitational collapse of rotating black holes. Of his more than 100 research articles, about one-fifth were written in his last decade.Besides his physics accomplishments, Huang was famous for his translations, in particular The Rubaiyat of Omar Khayyam: A Rendition in Classical Chinese Quatrains and I Ching, the Oracle. He also wrote many English and Chinese poems and published several books of original poetry; people in the poetry community referred to Huang as “a poet [who] also did physics research.”© 2017 American Institute of Physics.

Galilean-invariant effective field theory for theX(3872)

XEFT is a low-energy effective field theory for charm mesons and pions that provides a systematically improvable description of the X(3872) resonance. A Galilean-invariant formulation of XEFT is introduced to exploit the fact that mass is very nearly conserved in the transition D*0 --> D0 pi0. The transitions D*0 --> D0 pi0 and X --> D0 D0-bar pi0 are described explicitly in XEFT. The effects of the decay D*0 --> D0 gamma and of short-distance decay modes of the X(3872), such as J/psi --> pi+ pi-, can be taken into account by using complex on-shell renormalization schemes for the D*0 propagator and for the D*0 D0-bar propagator in which the positions of their complex poles are specified. Galilean-invariant XEFT is used to calculate the D*0 D0-bar scattering length to next-to-leading order. Galilean invariance ensures the cancellation of ultraviolet divergences without the need for truncating an expansion in powers of the ratio of the pion and charm meson masses.

Nuclei: superheavy–superneutronic–strange–and of antimatter

The extension of the periodic system into various new areas is investigated. Experiments for the synthesis of superheavy elements and the predictions of magic numbers are reviewed. Further on, investigations on hypernuclei and the possible production of antimatter-clusters in heavy-ion collisions are reported. Various versions of the meson field theory serve as effective field theories at the basis of modern nuclear structure and suggest structure in the vacuum which might be important for the production of hyper- and antimatter.

Extension of the periodic system: superheavy, superstrange and antimatter nuclei

The extension of the periodic system into various new areas is investigated. Experiments for the synthesis of superheavy elements and the predictions of magic numbers are reviewed. Further on, investigations on hypernuclei and the possible production of antimatter-clusters in heavy-ion collisions are reported. Various versions of the meson field theory serve as effective field theories at the basis of modern nuclear structure and suggest structure in the vacuum which might be important for the production of hyper- and antimatter.

Novel clusters in nuclear physics: superheavy, superstrange, antimatter

The extension of the periodic system into various new areas is investigated. Experiments for the synthesis of superheavy elements and the predictions of magic numbers are reviewed. Further on, investigations on hypernuclei and the possible production of antimatter-clusters in heavy-ion collisions are reported. Various versions of the meson field theory serve as effective field theories at the basis of modern nuclear structure and suggest structure in the vacuum which might be important for the production of hyper- and antimatter.

Chiral expansion of theπ0→γγdecay width

A chiral field theory of mesons has been applied to study the contribution of the current quark masses to the ${\ensuremath{\pi}}^{0}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}$ decay width at the next leading order. In this study, the large ${N}_{C}$ limit is assumed in order that the approach performed is consistent. The consequence that some low-energy constants from $\mathcal{L}(6{)}_{\mathrm{WZW}}$ can be read off from the final expressions is an interesting result. $(1.44\ifmmode\pm\else\textpm\fi{}0.67)%$ enhancement has been predicted and there is no new parameter.

Superheavy nuclei and beyond: hypermatter and antimatter

The extension of the periodic system into various new areas is investigated. Experiments for the synthesis of superheavy elements and the predictions of magic numbers are reviewed. Further on, investigations on hypernuclei and the possible production of antimatter-clusters in heavy-ion collisions are reported. Various versions of the meson field theory serve as effective field theories at the basis of modern nuclear structure and suggest structure in the vacuum which might be important for the production of hyper- and antimatter.

EXTENSION OF THE PERIODIC SYSTEM: SUPERHEAVY, SUPERSTRANGE, ANTIMATTER NUCLEI

The extension of the periodic system into various new areas is investigated. Experiments for the synthesis of superheavy elements and the predictions of magic numbers are reviewed. Further on, investigations on hypernuclei and the possible production of antimatter-clusters in heavy-ion collisions are reported. Various versions of the meson field theory serve as effective field theories at the basis of modern nuclear structure and suggest structure in the vacuum which might be important for the production of hyper- and antimatter.

Chiral field theory of0−+glueball

A chiral field theory of $0^{-+}$ glueball is presented. By adding a $0^{-+}$ glueball field to a successful Lagrangian of chiral field theory of pseudoscalar, vector, and axial-vector mesons, the Lagrangian of this theory is constructed. The couplings between the pseodoscalar glueball field and mesons are via U(1) anomaly revealed. Qualitative study of the physical processes of the $0^{-+}$ glueball of $m=1.405\textrm{GeV}$ is presented. The theoretical predictions can be used to identify the $0^{-+}$ glueball.

Complex-mass renormalization in chiral effective field theory

We consider a low-energy effective field theory of vector mesons and Goldstone bosons using the complex-mass renormalization. As an application we calculate the mass and the width of the ρ meson.

Analytic solution of Hedin’s equations in zero dimensions

Feynman diagrams for the many-body perturbational theory are enumerated by solving the system of Hedin’s equations in zero dimension. We extend the treatment of Molinari [Phys. Rev. B 71, 113102 (2005)] and give a complete solution of the enumeration problem in terms of Whittaker functions. An important relation between the generating function of the electron propagator and anomalous dimension in quantum field theory of massless fermions and mesons in four dimensions (Yukawa theory) is found. The Hopf algebra of undecorated rooted trees yields the anomalous field dimension in terms of the solution of the same differential equation. Its relation to the mathematical problem of combinatorics of chord diagrams is discussed; asymptotic expansions of the counting numbers are obtained.

J/ψcouplings to charmed resonances and toπ

We present an evaluation of the strong couplings JD^(*)D^(*) and JD^(*)D^(*)pi by an effective field theory of quarks and mesons. These couplings are necessary to calculate pi+J/psi --> D^(*)+barD^(*) cross sections, an important background to the J/psi suppression signal in the quark-gluon plasma. We write down the general effective lagrangian and compute the relevant couplings in the soft pion limit and beyond.

Felix Marc Hermann Villars

Felix Marc Hermann Villars