Role of Scalar Meson Resonances in $K_{L}^{0} \rightarrow \pi^{0} \gamma \gamma Decay

Corrections to $K_{L}^{0}\rightarrow \pi^{0} \gamma \gamma$ decay induced by scalar meson exchange are studied within chiral perturbation theory. In spite of bad knowledge of scalar-mesons parameters, the calculated branching ratio can be changed by a few percent.Comment: 18 pages of text, 2 figures (available upon request); preprint IJS-TP-16-94 , TUM-T31-63-94

Long distance contribution to K+→π+ννˉK^+ \to \pi^+ \nu {\bar \nu} decay and O(p4)O(p^4) terms in CHPT

The long distance contribution to $K^+ \to \pi^+ \nu {\bar \nu}$ is calculated using chiral perturbation theory. The leading contribution comes from $O(p^4)$ tree terms. The branching ratio of the $O(p^4)$ long distance contribution is found to be of order $10_{-3}$ smaller than the short distance contributions.Comment: 12 pages, 1 figure (available upon request

The Role of Underutilization of Protective Behavioral Strategies in the Relation of Social Anxiety with Risky Drinking

Social anxiety is prominent among undergraduates and increases the risk of experiencing alcohol problems. In fact, social anxiety more than quadruples the risk of developing an alcohol use disorder, yet it is inconsistently related to heavier drinking. Inconsistent findings may be due to lack of attention on protective behavioral strategies (PBS) among socially anxious drinkers. PBS are cognitive-behavioral strategies to reduce drinking and alcohol-related harm. Due to the nature of social anxiety, affected individuals may be especially vulnerable to PBS underutilization, leading to heavier and more problematic drinking. The current study examined the mediating role of PBS in the relationships of social anxiety with past-month drinking and alcohol problems using cross-sectional data among current (past-month) heavy undergraduate drinkers (N = 431). Social anxiety was significantly positively related to past-month alcohol problems and peak drinking. Social anxiety was significantly negatively related to typical drinking, drinking frequency, and PBSS Manner of Drinking. Social anxiety was indirectly (via PBSS Manner of Drinking) related to greater past-month peak drinks and more drinking problems. Findings suggest that socially anxious persons may be vulnerable to heavier and more problematic drinking due to PBS underutilization. Treatment implications are discussed

Rare Kaon Decays in the 1/Nc1/N_c-Expansion

We study the unknown coupling constants that appear at order $p^4$ in the Chiral Perturbation Theory analysis of $K \to \pi \gamma^* \to \pi l^+ l^-$, $K^{+-} \to \pi^{+-} \gamma \gamma$ and $K \to \pi \pi \gamma$ decays. To that end, we compute the chiral realization of the $\Delta S \, = \, 1$ Hamiltonian in the framework of the $1/N_c$-expansion of the low-energy action. The phenomenological implications are also discussed.Comment: 18 pages, LaTeX, CPT-92/P.279

Dispersion Relation Bounds for pi pi Scattering

Axiomatic principles such as analyticity, unitarity and crossing symmetry constrain the second derivative of the pi pi scattering amplitudes in some channels to be positive in a region of the Mandelstam plane. Since this region lies in the domain of validity of chiral perturbation theory, we can use these positivity conditions to bound linear combinations of \bar{l}_1 and \bar{l}_2. We compare our predictions with those derived previously in the literature using similar methods. We compute the one-loop pi pi scattering amplitude in the linear sigma model (LSM) using the MS-bar scheme, a result hitherto absent in the literature. The LSM values for \bar{l}_1 and \bar{l}_2 violate the bounds for small values of m_sigma/m_pi. We show how this can occur, while still being consistent with the axiomatic principles.Comment: 12 pages, 8 figures. Two references added, a few minor changes. Published versio

One loop corrections to quantum hadrodynamics with vector mesons

The renormalized elastic $\pi\pi$ scattering amplitude to one loop is calculated in the chiral limit in the $\sigma$ model and in a Quantum Hadrodynamic model (QHD-III) with vector mesons. It is argued that QHD-III reduces to the linear $\sigma$ model in the limit that the vector meson masses become large. The pion decay constant is also calculated to 1-loop in the $\sigma$ model, and at tree level in QHD-III; it is shown that the coefficient of the tree level term in the scattering amplitude equals $F_\pi^{-2}$. The 1-loop correction of $F_\pi$ in QHD-III violates strong isospin current conservation. Thus,it is concluded that QHD-III can, at best, only describe the strongly interacting nuclear sector.Comment: 6 page

Navigation-Assisted Posterior Open Reduction and Internal Fixation in a C-CLAMP Fashion for an Isolated C1 Fracture.

C1 fractures with an intact transverse ligament are usually treated conservatively. Patients who present with a progressive diastasis of bone fragments and a progressive articular subluxation mainly attributed to progressive lengthening of the transverse ligament (TAL) fibers can be treated with a C1 "C-clamp" fusion. A 75-year-old male who sustained a motor vehicle accident was neurologically intact. A computed tomography (CT) imaging demonstrated a Jefferson's type-C1 fracture with a slight lateral displacement of the C1 left lateral mass (LM) and a rotatory subluxation on the right. MRI showed an intact TAL and demonstrated an isolated rupture of the left alar ligament. Conservative treatment was chosen. Radiographic follow-up showed, at 3 months, progressive lateral mass displacement, most likely due to elongation of the TAL fibers; this was also associated with a persistent mechanical neck pain. For this reason, we performed a posterior reduction and internal fixation in a C-clamp fashion by placement of C1 lateral mass screws and posterior compression sparing the C1-2 joint. Using navigation, a 3.5-mm screw was inserted into the LM bilaterally. The screw heads were then connected with a rod and compression was applied before tightening. Postoperative CT scan demonstrated a satisfying reduction and further imaging will be made during the follow-up. The patient had a considerable relief of neck pain. Simple lateral mass fixation with C-clamp technique is a reasonable option in case of isolated C1 fractures in patients who have failed conservative management while preserving the range of motion (ROM) at the atlanto-axial joint. The link to the video can be found at: https://youtu.be/x8bsVwzCt_M

Radiative Kaon Decays K±→π±π0γK^\pm\to\pi^\pm\pi^0\gamma and Direct CP Violation

It is stressed that a measurement of the electric dipole amplitude for direct photon emission in \kpm decays through its interference with inner bremsstrahlung is important for differentiating among various models. Effects of amplitude CP violation in the radiative decays of the charged kaon are analyzed in the Standard Model in conjunction with the large $N_c$ approach. We point out that gluon and electromagnetic penguin contributions to the CP-violating asymmetry between the Dalitz plots of \kpm are of equal weight. The magnitude of CP asymmetry ranges from $2\times 10^{-6}$ to $1\times 10^{-5}$ when the photon energy in the kaon rest frame varies from 50 MeV to 170 MeV.Comment: Latex, 11 pages, ITP-SB-93-36, IP-ASTP-22-9

Vector and Scalar Meson Resonances in K→πππK\rightarrow\pi\pi\pi Decays

Corrections to $K\rightarrow\pi\pi\pi$ induced by vector and scalar meson exchange are investigated within chiral perturbation theory.Comment: 15pages, Latex-file, TUM-T31-41/9

Rare Kaon Decays

The current status of rare kaon decay experiments is reviewed. New limits in the search for Lepton Flavor Violation are discussed, as are new measurements of the CKM matrix.Comment: 8 pages, 3 figures, LaTeX, presented at the 3rd International Conference on B Phyiscs and CP Violation, Taipei December 3-7, 199