Varied Signature Splitting Phenomena in Odd Proton Nuclei

Varied signature splitting phenomena in odd proton rare earth nuclei are investigated. Signature splitting as functions of $K$ and $j$ in the angular momentum projection theory is explicitly shown and compared with those of the particle rotor model. The observed deviations from these rules are due to the band mixings. The recently measured $^{169}$Ta high spin data are taken as a typical example where fruitful information about signature effects can be extracted. Six bands, two of which have not yet been observed, were calculated and discussed in detail in this paper. The experimentally unknown band head energies are given

Computing the minimum k-Cover of a string

We study the minimum k-cover problem. For a given string x of length n and an integer k, the minimum k-cover is the minimum set of k-substrings that covers x. We show that the on-line algorithm that has been proposed by Iliopoulos and Smyth [IS92] is not correct. We prove that the problem is in fact NP-hard. Furthermore, we propose two greedy algorithms that are implemented and tested on different kind of data

Verifying a border array in linear time

A border of a string x is a proper (but possibly empty) prefix of x that is also a suffix of x. The border array β = β[1..n] of a string x = x[1..n] is an array of nonnegative integers in which each element β[i], 1 ≤ i ≤ n, is the length of the longest border of x[1..i]. In this paper we first present a simple linear-time algorithm to determine whether or not a given array y = y[1..n] of integers is a border array of some string on an alphabet of unbounded size. We state as an open problem the design of a corresponding and equally efficient algorithm on an alphabet of bounded size α. We then consider the problem of generating all possible distinct border arrays of given length n on a bounded or unbounded alphabet, and doing so in time proportional to the number of arrays generated. A previously published algorithm that claims to solve this problem in constant time per array generated is shown to be incorrect, and new algorithms are proposed. We state as open the design of an equally efficient on-line algorithm for this problem

Pion-Muon Asymmetry Revisited

Long ago an unexpected and unexplainable phenomena was observed. The distribution of muons from positive pion decay at rest was anisotropic with an excess in the backward direction relative to the direction of the proton beam from which the pions were created. Although this effect was observed by several different groups with pions produced by different means, the result was not accepted by the physics community, because it is in direct conflict with a large set of other experiments indicating that the pion is a pseudoscalar particle. It is possible to satisfy both sets of experiments if helicity-zero vector particles exist and the pion is such a particle. Helicity-zero vector particles have direction but no net spin. For the neutral pion to be a vector particle requires an additional modification to conventional theory as discussed herein. An experiment is proposed which can prove that the asymmetry in the distribution of muons from pion decay is a genuine physical effect because the asymmetry can be modified in a controllable manner. A positive result will also prove that the pion is NOT a pseudoscalar particle.Comment: 9 pages, 3 figure

Post-Combustion CO2 Capture Demonstration Using Supported Amine Sorbents: Design and Evaluation of 200 kWth Pilot

CO2 capture using supported amine sorbents is a promising post-combustion capture technology. With regard to supported amine sorbents, the most important issues exist in the regeneration process. In this paper, various regeneration strategies including thermal regeneration in pure CO2 stream, vacuum regeneration, and steam-stripping regeneration are put forward and compared from the aspect of energy consumption. Besides, to ensure the long-term thermal and chemical stability and high working capacity, a kind of supported amine sorbent with the amine groups bonded to the support was tested and employed. As to the regeneration characteristics, the sorbent can be regenerated completely in pure CO2 and has perfect cyclic stability. Finally, one 200 kWth pilot plant was designed and constructed to demonstrate the process feasibility of continuous CO2 capture from flue gases with supported amine sorbents. The selection of the type of absorber and regenerator is discussed in detail. The pilot was evaluated for the air tightness and heat transfer issues

A Phenomenological Analysis of Heavy Hadron Lifetimes

A phenomenological analysis of lifetimes of bottom and charmed hadrons within the framework of the heavy quark expansion is performed. The baryon matrix element is evaluated using the bag model and the nonrelativistic quark model. We find that bottom-baryon lifetimes follow the pattern $\tau(\Omega_b)\simeq\tau(\Xi_b^-)>\tau(\Lambda_b)\simeq\tau(\Xi_b^0)$. However, neither the lifetime ratio $\tau(\Lambda_b)/\tau( B_d)$ nor the absolute decay rates of the $\Lambda_b$ baryon and $B$ mesons can be explained. One way of solving both difficulties is to allow the presence of linear $1/m_Q$ corrections by scaling the inclusive nonleptonic width with the fifth power of the hadron mass $m_{H_Q}$ rather than the heavy quark mass $m_Q$. The hierarchy of bottom baryon lifetimes is dramatically modified to $\tau(\Lambda_b)>\tau(\Xi_b^-)>\tau(\Xi_b^0)>\tau( \Omega_b)$: The longest-lived $\Omega_b$ among bottom baryons in the OPE prescription now becomes shortest-lived. The replacement of $m_Q$ by $m_{H_Q}$ in nonleptonic widths is natural and justified in the PQCD-based factorization approach formulated in terms of hadron-level kinematics. For inclusive charmed baryon decays, we argue that since the heavy quark expansion does not converge, local duality cannot be tested in this case. We show that while the ansatz of substituting the heavy quark mass by the hadron mass provides a much better description of the charmed-baryon lifetime {\it ratios}, it appears unnatural and unpredictive for describing the {\it absolute} inclusive decay rates of charmed baryons, contrary to the bottom case.Comment: 35 pages, to appear in Phys. Rev. The CDF result on the lifetime ratio of Lambda_b and B_d is discusse

Spin fluctuations in nearly magnetic metals from ab-initio dynamical spin susceptibility calculations:application to Pd and Cr95V5

We describe our theoretical formalism and computational scheme for making ab-initio calculations of the dynamic paramagnetic spin susceptibilities of metals and alloys at finite temperatures. Its basis is Time-Dependent Density Functional Theory within an electronic multiple scattering, imaginary time Green function formalism. Results receive a natural interpretation in terms of overdamped oscillator systems making them suitable for incorporation into spin fluctuation theories. For illustration we apply our method to the nearly ferromagnetic metal Pd and the nearly antiferromagnetic chromium alloy Cr95V5. We compare and contrast the spin dynamics of these two metals and in each case identify those fluctuations with relaxation times much longer than typical electronic `hopping times'Comment: 21 pages, 9 figures. To appear in Physical Review B (July 2000

Direct Measurements of the Branching Fractions for D0→K−e+νeD^0 \to K^-e^+\nu_e and D0→π−e+νeD^0 \to \pi^-e^+\nu_e and Determinations of the Form Factors f+K(0)f_{+}^{K}(0) and f+π(0)f^{\pi}_{+}(0)

The absolute branching fractions for the decays $D^0 \to K^-e ^+\nu_e$ and $D^0 \to \pi^-e^+\nu_e$ are determined using $7584\pm 198 \pm 341$ singly tagged $\bar D^0$ sample from the data collected around 3.773 GeV with the BES-II detector at the BEPC. In the system recoiling against the singly tagged $\bar D^0$ meson, $104.0\pm 10.9$ events for $D^0 \to K^-e ^+\nu_e$ and $9.0 \pm 3.6$ events for $D^0 \to \pi^-e^+\nu_e$ decays are observed. Those yield the absolute branching fractions to be $BF(D^0 \to K^-e^+\nu_e)=(3.82 \pm 0.40\pm 0.27)$ and $BF(D^0 \to \pi^-e^+\nu_e)=(0.33 \pm 0.13\pm 0.03)$. The vector form factors are determined to be $|f^K_+(0)| = 0.78 \pm 0.04 \pm 0.03$ and $|f^{\pi}_+(0)| = 0.73 \pm 0.14 \pm 0.06$. The ratio of the two form factors is measured to be $|f^{\pi}_+(0)/f^K_+(0)|= 0.93 \pm 0.19 \pm 0.07$.Comment: 6 pages, 5 figure