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L. S. Kisslinger

Publications and source records attributed to L. S. Kisslinger.

At least 19 recordsLinked to original sources
arXiv2010

QCD Sum Rules and the Induced Pseudoscalar Coupling

We present an extension of the QCD sum rule method in the external fields so as to determine the induced pseudoscalar coupling constant g_P, which tests the validity of the partially conserved axial current (PCAC) hypothesis. This is essentially that we pick out the "higher-order" effects of both the hadron and quark (QCD) sides. A specific QCD sum rules for g_P is obtained and its prediction is briefly analyzed. It turns out that the final prediction on g_P is extremely stable. In view of the versatile nature of the present QCD sum rule methods, we appendix some discussions on the possible future of the method.

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arXiv2007

Light vector hybrid states via QCD sum rules

Vector hybrid states with light quarks $u,d,s$ are investigated via QCD sum rules. The results show that the masses of the $q{\bar q}g$ $(q=u,d)$, $q{\bar s}g$, and $s{\bar s}g$ states with $J^{PC}=1^{--}$ are about 2.3-2.4, 2.3-2.5, and 2.5-2.6 GeV, respectively. It suggests that the recently discovered Y(2175) could not be a pure $s{\bar s}g$ vector hybrid state.

hep-ph↗
arXiv2006

Neutron spin polarization in strong magnetic fields

The effects of strong magnetic fields on the inner crust of neutron stars are investigated after taking into account the anomalous magnetic moments of nucleons. Energy spectra and wave functions for protons and neutrons in a uniform magnetic field are provided. The particle spin polarizations and the yields of protons and neutrons are calculated in a free Fermi gas model. Obvious spin polarization occurs when $B\geq10^{14}$G for protons and $B\geq10^{17}$G for neutrons, respectively. It is shown that the neutron spin polarization depends solely on the magnetic field strength.

astro-ph↗
arXiv2005

Effect of isovector-scalar meson on neutron star matter in strong magnetic fields

We study the effects of isovector-scalar meson $δ$ on the equation of state (EOS) of neutron star matter in strong magnetic fields. The EOS of neutron-star matter and nucleon effective masses are calculated in the framework of Lagrangian field theory, which is solved within the mean-field approximation. From the numerical results one can find that the $δ$-field leads to a remarkable splitting of proton and neutron effective masses. The strength of $δ$-field decreases with the increasing of the magnetic field and is little at ultrastrong field. The proton effective mass is highly influenced by magnetic fields, while the effect of magnetic fields on the neutron effective mass is negligible. The EOS turns out to be stiffer at $B < 10^{15}$G but becomes softer at stronger magnetic field after including the $δ$-field. The AMM terms can affect the system merely at ultrastrong magnetic field($B > 10^{19}$G). In the range of $10^{15}$ G -- $10^{18}$ G the properties of neutron-star matter are found to be similar with those without magnetic fields.

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arXiv2004

Non-abelian dynamics in first-order cosmological phase transitions

Bubble collisions in cosmological phase transitions are explored, taking the non-abelian character of the gauge fields into account. Both the QCD and electroweak phase transitions are considered. Numerical solutions of the field equations in several limits are presented.

hep-ph↗
arXiv2002

Continuity of generalized parton distributions for the pion virtual Compton scattering

We discuss a consistent treatment of the light-front gauge-boson and meson wave functions in the analyses of the generalized parton distributions(GPDs) and the scattering amplitudes in deeply virtual Compton scattering(DVCS) for the pion. The continuity of the GPDs at the crossover, where the longitudinal momentum fraction of the probed quark is same with the skewedness parameter, and the finiteness of the DVCS amplitude are ensured if the same light-front radial wave function as that of the meson bound state wave function is used for the gauge boson bound state arising from the pair-creation(or nonvalence) diagram. The frame-independence of our model calculation is also guaranteed by the constraint from the sum rule between the GPDs and the form factors.

hep-ph↗
arXiv2002

Light-front quark model analysis of rare $B\to K\ell^+\ell^-$ decays

Using the light-front quark model, we calculate the transition form factors, decay rates, and longitudinal lepton polarization asymmetries for the exclusive rare $B\to K\ell^+\ell^-(\ell=e,μ,τ$) decays within the standard model. Evaluating the timelike form factors, we use the analytic continuation method in $q^+=0$ frame to obtain the form factors $F_+$ and $F_T$, which are free from zero-mode. The form factor $F_-$ which is not free from zero-mode in $q^+ = 0$ frame and contaminated by the higher(or nonvalence) Fock states in $q^+ \neq 0$ frame is obtained from an effective treatment for handling the nonvalence contribution based on the Bethe-Salpeter formalism. The covariance(i.e. frame-independence) of our model calculation is discussed. We obtain the branching ratios for ${\rm BR}(B\to K\ell^+\ell^-)$ as $4.96\times10^{-7}|V_{ts}/V_{cb}|^2$ for $\ell=e,μ$ and $1.27\times 10^{-7}|V_{ts}/V_{cb}|^2$ for $\ell=τ$.

hep-ph↗
arXiv2001

Light-cone representation of the quark Schwinger-Dyson equation

We use a light-cone approach to solve the Schwinger-Dyson equation for the quark propagator. We show how this method can be used to solve the equation beyond the space-like region, to which one is usually restricted with the usual Euclidean-space approach. We work in the Landau gauge, and use an infrared-enhanced model for the gluon propagator and include instanton effects to get both confinement and vacuum condensates. With our models, reasonable fits to known quantities are obtained, resulting in a light-cone quark propagator that can be used for hadronic physics at all momentum transfers.

hep-ph↗
arXiv2001

Skewed quark distribution of the pion in the light-front quark model

We calculate the skewed quark distributions(SQDs) of the pion in the light-front quark model, and discuss the calculation of the nonvalence contribution to the SQDs in this model. The frame-independence of our model calculation is guaranteed by the constraint of the sum rule between the SQDs and form factor. Our numerical results show large nonvalence contributions to the SQDs at small momentum transfer region as the skewedness increases.

hep-ph↗
arXiv2001

Nonleptonic Hyperon Decays with QCD Sum Rules

Despite measurements which date more than 20 years ago, no straightforward solution of the ratio of the parity-conserving (P-wave) to parity- violating (S-wave) decays of the hyperons has been obtained. Here we use two 2-point methods in QCD sum rules to examine the problem. We find that resonance contributions are needed to fit the data, similar to a chiral perturbation theory treatment.

hep-ph↗
arXiv2001

Pion Form Factor and Quark Mass Evolution in a Light-Front Bethe-Salpeter Model

We discuss the soft contribution to the elastic pion form factor with the mass evolution from current to constituent quark being taken into account using a light-front Bethe-Salpeter (LFBS) model, which is a light-front quark model (LFQM) with a running mass. It is shown that partial conservation of the axial-vector current (PCAC) is satisfied with a running quark mass. We examine the sensitivity of the pion form factor using two different functional forms of the quark propagator. The Ball-Chiu ansatz is used to maintain local gauge invariance of the quark-photon vertex. The extension of our model to the hard contribution is also discussed.

hep-ph↗
arXiv1999

Quark propagator, instantons and gluon propagator

The Schwinger-Dyson formalism is used to check the consistency of instanton model solutions for the quark propagator with recent models of confining gluon propagators. We find that the models are not consistent. A major discrepancy is the absence of a vector condensate in the instanton model that is present in the solutions with nonperturbative confining gluons.

hep-ph↗
arXiv1998

Mesons as qbar-q Bound States from Euclidean 2-Point Correlators in the Bethe-Salpeter Approach

We investigate the 2-point correlation function for the vector current. The gluons provide dressings for both the quark self energy as well as the vector vertex function, which are described consistently by the rainbow Dyson-Schwinger equation and the inhomogeneous ladder Bethe-Salpeter equation. The form of the gluon propagator at low momenta is modeled by a 2-parameter ansatz fitting the weak pion decay constant. The quarks are confined in the sense that the quark propagator does not have a pole at timelike momenta. We determine the ground state mass in the vector channel from the Euclidean time Fourier transform of the correlator, which has an exponential falloff at large times. The ground state mass lies around 590 MeV and is almost independent of the model form for the gluon propagator. This method allows us to stay in Euclidean space and to avoid analytic continuation of the quark or gluon propagators into the timelike region.

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arXiv1998

Structure of Vacuum Condensates

It is essential to know the space-time structure of the nonlocal vacuum condensates for application to medium energy processes. Using the Dyson-Schwinger formalism in the rainbow approximation for the quark propagator, we study the nonlocal quark condensate and model forms for the nonperturbative gluon propagator constrained by fits to local condensates and deep inelastic scattering with nucleon targets.

hep-ph↗
arXiv1996

QED Penguin Contributions To Isospin Splittings of Heavy-Light Quark Systems

Recent experiments show that the isospin-violating mass splitting of the B mesons is very small, but the best fits with a QCD sum rule analysis give a splitting of at least 1.0 MeV. The isospin-violating mass splittings of the charmed mesons, on the other hand, are in agreement with experiment. In this letter we show that the inclusion of 2$^{nd}$ kind QED penguin diagrams can account for this discrepancy within the errors in the QCD sum rule method.

hep-ph↗
arXiv1995

The Weak Parity-Violating Pion-Nucleon Coupling (Revised)

We use QCD sum rules to obtain the weak parity-violating pion-nucleon coupling constant $f_{πNN}$. We find that $f_{πNN}\approx 2\times 10^{-8}$, about an order of magnitude smaller than the ``best estimates'' based on quark models. This result follows from the cancellation between perturbative and nonperturbative QCD processes not found in quark models, but explicit in the QCD sum rule method. Our result is consistent with the experimental upper limit found from $^{18}$F parity-violating measurements.

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