Virtual light-by-light scattering and the g factor of a bound electron

The contribution of the light-by-light diagram to the g factor of electron and muon bound in Coulomb field is obtained. For electron in a ground state, our results are in good agreement with the results of other authors obtained numerically for large Z. For relatively small Z our results have essentially higher accuracy as compared to the previous ones. For muonic atoms, the contribution is obtained for the first time with the high accuracy in whole region of Z.Comment: 10 pages, 3 figures, RevTe

Laser-Induced Spall Of Aluminum And Aluminum Alloys At High Strain Rates

We conducted laser-induced spall experiments aimed at studying how a material's microstructure affects the tensile fracture characteristics at high strain rates (> 10(6) s(-1)). We used the Z-Beamlet Laser at Sandia National Laboratory to drive shocks and to measure the spall strength of aluminum targets with various microstructures. The targets were recrystallized, high-purity aluminum (Al-HP RX), recrystallized aluminum + 3 wt.% magnesium (Al-3Mg RX), and cold-worked aluminum + 3 wt.% magnesium (Al-3Mg CW). The Al-3Mg RX and Al-3Mg CW are used to explore the roles that solid-solution alloying and cold-work strengthening play in the spall process. Using a line-VISAR (Velocity Interferometer System for Any Reflector) and analysis of recovered samples, we were able to measure spall strength and determine failure morphology in these targets. We find that the spall strength is highest for Al-HP RX. Analysis reveals that material grain size plays a vital role in the fracture morphology and spall strength results.Mechanical Engineerin

Evidence for Static Magnetism in the Vortex Cores of Ortho-II YBa2_2Cu3_3O6.50_{6.50}

Evidence for static alternating magnetic fields in the vortex cores of underdoped YBa$_2$Cu$_3$O$_{6+x}$ is reported. Muon spin rotation measurements of the internal magnetic field distribution of the vortex state of YBa$_2$Cu$_3$O$_{6.50}$ in applied fields of $H = 1$ T and $H = 4$ T reveal a feature in the high-field tail of the field distribution which is not present in optimally doped YBa$_2$Cu$_3$O$_{6.95}$ and which fits well to a model with static magnetic fields in the vortex cores. The magnitude of the fields is estimated to be 18(2) G and decreases above $T = 10$ K. We discuss possible origins of the additional vortex core magnetism within the context of existing theories.Comment: Submitted to PRL; corresponding author: [email protected]

Hidden magnetic transitions in thermoelectric layered cobaltite, [Ca2_2CoO3_3]0.62_{0.62}[CoO2_2]

A positive muon spin rotation and relaxation ($\mu^+$SR) experiment on [Ca$_2$CoO$_3$]$_{0.62}$[CoO$_2$], ({\sl i.e.}, Ca$_3$Co$_4$O$_9$, a layered thermoelectric cobaltite) indicates the existence of two magnetic transitions at $\sim$ 100 K and 400 - 600 K; the former is a transition from a paramagnetic state to an incommensurate ({\sf IC}) spin density wave ({\sf SDW}) state. The anisotropic behavior of zero-field $\mu^+$SR spectra at 5 K suggests that the {\sf IC-SDW} propagates in the $a$-$b$ plane, with oscillating moments directed along the c-axis; also the {\sf IC-SDW} is found to exist not in the [Ca$_2$CoO$_3$] subsystem but in the [CoO$_2$] subsystem. In addition, it is found that the long-range {\sf IC-SDW} order completes below $\sim$ 30 K, whereas the short-range order appears below 100 K. The latter transition is interpreted as a gradual change in the spin state of Co ions %% at temperatures above 400 K. These two magnetic transitions detected by $\mu^+$SR are found to correlate closely with the transport properties of [Ca$_2$CoO$_3$]$_{0.62}$[CoO$_2$].Comment: 7 pages, 8 figures. to be appeared in Phys. Rev.

Recent Cases

Constitutional Law-First Amendment-School Authorities May Prohibit High School Student\u27s Distribution of Sex Questionnaire to Prevent Possible Psychological Harm to Other Students Robert Edward Banta Plaintiff, editor of a high school publication,\u27 brought suit in federal court seeking an order compelling defendant school officials to allow the student publication to distribute a sex questionnaire,to students in the high school and to publish the results. Plaintiff claimed that defendants had not shown that the planned distribution would disrupt school activities and that, therefore, defendants\u27prohibition of the questionnaire violated 42 U.S.C. § 19831 and the first and fourteenth amendments. Pointing to potential psychological harm to students, defendants argued that the state\u27s interest in protecting the students\u27 emotional well-being outweighed plaintiffs interest in distributing the questionnaire. The trial court held that defendants could prohibit distribution of the questionnaire to ninth-and tenth-grade students but not to eleventh- and twelfth-grade students. On appeal to the United States Court of Appeals for the Second Circuit, held, reversed in part\u27 and remanded with instructions to dismiss the complaint. If school officials reasonably believe that distribution on school grounds of a high school student\u27s questionnaire soliciting information about the sexual habits of his fellow students might cause psychological harm to other students, then prohibition of the questionnaire does not violate the right to freedom of expression of the student seeking to distribute the questionnaire. Trachtman v. Anker, 563 F.2d 512 (2d Cir. 1977). Corporations--Freeze-Out Mergers--The Delaware Supreme Court Requires Majority Shareholder Proof of a Valid Business Purpose As a Component of Entire Fairness in Freeze-Out Merger Challenges Oby T. Brewer, III Recent declines in stock market averages\u27 accompanied by costly disclosure requirements imposed under the federal securities laws have prompted many companies to reconsider their positions as publicly held corporations. In response to the resulting minimal benefits of public ownership, many controlling shareholders now seek to increase their control and participation in a corporation\u27s future profits by going private.\u27 One means of going private is the freeze-out merger, by which a parent company forces the liquidation of minority interests in a publicly held subsidiary through a merger of the subsidiary with the parent. By complying with applicable state merger statutes, the parent may eliminate the minority\u27s shares by tendering a cash-out price, which the minority either must accept or have appraised judicially. The merger statutes thus represent a legislative compromise between total majority control and the single vote veto available to the minority at common law. Criminal Procedure--Prosecutorial Immunity-Federal Prosecutor Is Not Absolutely Immune From Suit for Alleged Perjury Cornelia Anne Clark Plaintiffs\u27 brought a civil action in tort charging that defendant federal prosecutor\u27s alleged perjury at a hearing incident to a grand jury investigation of plaintiffs\u27 activities\u27 violated their constitutional rights. On motion to dismiss, defendant contended that he enjoyed absolute quasi-judicial immunity because he had been acting at the hearing in his official capacity as a special federal prosecutor. The district court\u27 denied the motion, holding that the doctrine of quasi-judicial immunity does not apply when the prosecutor is alleged to have committed perjury. On interlocutory appeal to the United States Court of Appeals for the District of Columbia Circuit, held, affirmed. Because a federal prosecutor\u27s perjury during a court hearing incident and prior to a grand jury investigation falls within his investigative duty rather than his advocatory duty,the prosecutor is entitled only to a qualified immunity.\u27 Briggs v.Goodwin, No. 75-1642 (D.C. Cir. Sept. 21, 1977). Securities Law--Rule 10b-5-Defense of In Pari Delicto Bars Private Damage Action Brought Against Tipper by Tippee Who Fails to Disclose Before Trading Terry Currie Tippees\u27 brought a private action for damages under section 10(b) of the Securities Exchange Act of 1934 and rule 10b-53 charging that defendant tippers disseminated false and misleading material inside information in advising plaintiffs of an imminent merger between two corporations that would result in appreciated stock values.\u27 In reliance on this information, plaintiffs purchased stock in one of the corporations and subsequently incurred substantial losses on the stock when the proposed merger did not occur. Defendants moved for summary judgment, claiming that the doctrine of in pari delicto barred plaintiffs\u27 recovery because plaintiffs also had violated rule 10b-5 by failing to make full disclosure of the inside information before trading on the open market.\u27 The district court granted the tippers\u27 motion for summary judgment. On appeal to the United States Court of Appeals for the Third Circuit, held, affirmed. When a tippee violates rule 10b-5 by failing to make full disclosure to the investing public of material inside information prior to trading on the open market, the defense of in pari delicto bars a rule 10b-5 private damage action by the tippee against the tipper. Torts--Negligence--Child Has Cause of Action for Preconception Medical Malpractice Douglas William Ey, Jr. Plaintiff, claiming that she suffered permanent physical injuries\u27 as a result of defendants\u27 conduct prior to her conception,sought to recover damages in a negligence action.2 In 1965 plaintiffs mother,who had Rh negative blood, was given two transfusions of incompatible Rh positive blood in defendant hospital where defendant physician was director of laboratories.\u27 Plaintiff\u27s mother did not discover that these transfusions had sensitized her blood until shortly before plaintiffs birth in 1973. Defendants moved to dis-miss for failure to state a cause of action, arguing that because plaintiff had not been conceived at the time of the alleged negligent conduct, defendants owed no duty of care to plaintiff. The trial court granted defendants\u27 motion, but the Illinois Appellate Court reversed and remanded the case for further proceedings. On appeal to the Supreme Court of Illinois, held, affirmed. A child injured by the negligent acts of a physician and a hospital committed against his mother prior to his conception has a cause of action based on negligence. Renslow v. Mennonite Hospital, 367 N.E.2d 1250 (Ill.1977)

Expansion of the Vortex Cores in YBa2Cu3O6.95 at Low Magnetic Fields

Muon spin rotation spectroscopy has been used to measure the effective size of the vortex cores in optimally doped YBa2Cu3O6.95 as a function of temperature and magnetic field deep in the superconducting state. While the core size at H=2T is close to 20 angstroms and consistent with that measured by STM at 6T, we find a striking increase in the core size at lower magnetic fields, where it approaches an extraordinarily large value of about 100 angstroms. This suggests that the average value of the superconducting coherence length in cuprate superconductors may be larger than previously thought at low magnetic fields.Comment: 9 pages, 4 figures, 1 text fil