An Exploratory Study of Nucleon-Nucleon Scattering Lengths in Lattice QCD

An exploratory study is made of the nucleon-nucleon $s$-wave scattering lengths in quenched lattice QCD with the Wilson quark action. The $\pi$-$N$ and $\pi$-$\pi$ scattering lengths are also calculated for comparison. The calculations are made with heavy quarks corresponding to $m_\pi/m_\rho\approx 0.73-0.95$. The results show that the $N$-$N$ system has an attractive force in both spin-singlet and triplet channels, with their scattering lengths significantly larger than those for the $\pi$-$N$ and $\pi$-$\pi$ cases, a trend which is qualitatively consistent with the experiment. Problems toward a more realistic calculation for light quarks are discussed.Comment: 9 pages. Latex file. Figures are also included as ps file

WZW-like Action for Heterotic String Field Theory

We complete the construction of the Neveu-Schwarz sector of heterotic string field theory begun in hep-th/0406212 by giving a closed-form expression for the action and gauge transformations. Just as the Wess-Zumino-Witten (WZW) action for open superstring field theory can be constructed from pure-gauge fields in bosonic open string field theory, our heterotic string field theory action is constructed from pure-gauge fields in bosonic closed string field theory. The construction involves a simple alternative form of the WZW action which is consistent with the algebraic structures of closed string field theory.Comment: 22 pages, no figures, LaTeX2

MS

thesisAlthough much work has been done by many investigators in the study of emphysema, the etiology and the pathogenesis of emphysema are still unknown. Therefore, a study was made to investigate the bacterial flora of patients with emphysema, to see if there was a species or strain of organisms peculiar to emphysema. These bacteria were tested (1) for their ability to multiply in pulmonary mucus in vitro, (2) to examine the surface tension properties of mucus in vitro, and (3) to examine the alteration of surface tension of culture media by microorganisms. Twenty-six patients from the Pulmonary Disease Service of the Veterans Administration Hospital, Salt Lake City, Utah were utilized in this study. An initial selection of patients known to have bronchitis, bronchiectasis, or emphysema and who did not have antibacterial chemotherapy for 6 months were chosen by the Chief of the Pulmonary Disease Service and resident physicians. Most studies of the sputum flora in patients with chronic bronchitis and bronchiectasis are based on bacteriological cultures of expectorated bronchial secretions. Contamination by nasopharyngeal microorganisms is inevitable, since bacteria known to be normal inhabitants of the pharynx are cultured from expectorated sputum. Bacteria isolated in this manner cannot be assumed to have significance in bronchial inflammation. This study was designed to compare qualitatively and quantitatively the bacterial flora of expectorated bronchial secretions and saliva in patients with chronic bronchitis or bronchiectasis, in an effort to assess the importance of contamination of the expectorated bronchial secretion by saliva. A comparison of the numbers of bacteria in saliva and sputum in 26 patients showed that there are tremendous numbers of bacteria in saliva. Even in a clean" mouth, saliva contained as large or larger numbers of bacteria than did expectorated sputum. The presence in both sputum and saliva of alpha hemolytic Streptococci, non-hemolytic Streptococci, the Neisseria species, non-hemolytic Staphylococcus aureus and non-hemolytic and hemolytic St. albus suggests a nasopharyngeal origin of these strains. The D. pneumoniae, hemolytic St. aureus, and the Hemophilus species were less frequently isolated from the sputum suggesting a bronchial origin for these organisms. Besides using the cultural technique for the isolation of D. pneumoniae, white mice were inoculated with saliva and sputum. It was found that animal inoculation yielded more positive isolations than by cultural methods in saliva. However, there was a greater number of isolation of D. pneumoniae by cultural technique from the sputum than by animal inoculation. Sterile sputum was employed as a substrate for the possible growth of bacteria from patients with emphysema, and it was found that some of these bacteria grew well in sputum. The surface tension measurements of sputa and broths were performed before and after incubation with organisms. This investigation has shown that the proliferation of microorganisms in sputum or broth either increased or decreased the surface tension of the sputum or broth depending on the bacteria

Conformal Symmetry and A New Gauge in the Matrix Model

We generalize the background gauge in the Matrix model to propose a new gauge which is useful for discussing the conformal symmetry. In this gauge, the special conformal transformation (SCT) as the isometry of the near-horizon geometry of the D-particle solution is directly reproduced with the correct coefficient as the quantum correction to the SCT in the Matrix model. We also present a general argument for the relation between the gauge choice and the field redefinition in the Matrix model.Comment: 17 pages, LaTeX, no figures; v2: Introduction modified, references added and typos corrected; v3: Introduction changed; v4: Eq.(12) corrected; v5: final version to appear in Phys. Rev.

Heterotic String Field Theory

We construct the Neveu-Schwarz sector of heterotic string field theory using the large Hilbert space of the superghosts and the multi-string products of bosonic closed string field theory. No picture-changing operators are required as in Wess-Zumino-Witten-like open superstring field theory. The action exhibits a novel kind of nonpolynomiality: in addition to terms necessary to cover missing regions of moduli spaces, new terms arise from the boundary of the missing regions and its subspaces. We determine the action up to quintic order and a subset of terms to all orders.Comment: 15 pages, no figures, LaTeX2e; v2: minor cosmetic change

Tachyon Vacuum Solution in Open String Field Theory with Constant B Field

We show that Schnabl's tachyon vacuum solution is an exact solution of the equation of motion of Witten's open bosonic string field theory in the background of constant antisymmetric two-form field. The action computed at the vacuum solution is given by the Dirac-Born-Infeld factor multiplied to that without the antisymmetric tensor field.Comment: 8 page

Rolling to the tachyon vacuum in string field theory

We argue that the rolling-tachyon solution in cubic OSFT proceeds at late times to precisely the analytic tachyon-vacuum solution constructed by Schnabl. In addition, we demonstrate the relationship between the rolling-tachyon solution and the standard BCFT description by showing that there is a finite gauge transformation which relates the two.Comment: 16 pages, 5 figures, References and comments adde

Renormalization of four-fermion operators for higher twist calculations

The evaluation of the higher twist contributions to Deep Inelastic Scattering amplitudes involves a non trivial choice of operator bases for the higher orders of the OPE expansion of the two hadronic currents. In this talk we discuss the perturbative renormalization of the four-fermion operators that appear in the above bases.Comment: LATTICE98(matrixelement), 3 page

Exact marginality in open string field theory: a general framework

We construct analytic solutions of open bosonic string field theory for any exactly marginal deformation in any boundary conformal field theory when properly renormalized operator products of the marginal operator are given. We explicitly provide such renormalized operator products for a class of marginal deformations which include the deformations of flat D-branes in flat backgrounds by constant massless modes of the gauge field and of the scalar fields on the D-branes, the cosine potential for a space-like coordinate, and the hyperbolic cosine potential for the time-like coordinate. In our construction we use integrated vertex operators, which are closely related to finite deformations in boundary conformal field theory, while previous analytic solutions were based on unintegrated vertex operators. We also introduce a modified star product to formulate string field theory around the deformed background.Comment: 63 pages, 10 figures, LaTeX2

Study of SU(3) vortex-like configurations with a new maximal center gauge fixing method

We present a new way of fixing the gauge to (direct) maximal center gauge in SU(N) Yang-Mills theory and apply this method to SU(3) configurations which are vortex-like. We study the structure of the Z_3 configurations obtained after center-projecting the SU(3) ones.Comment: 11 pages, 2 figures. To appear in PL