Global symmetries of the D = 4 supergravity effective theory consistent with the compactification... more Global symmetries of the D = 4 supergravity effective theory consistent with the compactification of the superstring are shown to form an SU (1, 1) X U (1) group of transformations acting on the dilaton, axion and matter fields. These are exact invariances of the K~ihler potential if they are preserved by integration over Kaluza-Klein massive states. A key role is played by the cubic superpotential which is also essential in implementing flatness of the scalar potential, a vanishing cosmological constant and thus effective global supersymmetry in the matter sector, at the classical level. This is shown by an explicit computation of the scalar potential. If only an axion-like non-compact subgroup is left unbroken by the superpotential, the cosmological constant turns out to be negative in some cases.
Our previous study revealed that the coefficient of variation of harmonic magnitude (HCV) of radi... more Our previous study revealed that the coefficient of variation of harmonic magnitude (HCV) of radial arterial pulse was significantly raised before the death of cancer patients. In this study, we recorded the caudate arterial pulse of 24 Sprague-Dawley rats that had a fatal dose of urethane injected into their abdomens. Twenty rats were dead within 3 hours after the injection and four survived. We defined the last 100 minutes of each rat's life as the dying process. During the dying process, we found that both the systolic blood pressure and diastolic blood pressure dropped steeply during the last 5 minutes. However, all HCVs, except HCV1, climbed steeply before the last 5 minutes. The HCV1 of the dying rats was significantly higher than that of rats that survived, starting from the first minute (P<0.01). The HCV2 of the dying rats was significantly higher than that of the survived rats starting from the 52nd minute (P<0.05). The HCV3 and HCV4 of the dying rats were significantly higher than those of the survived rats until the 70th minute and the 80th minute, respectively (P<0.05). Furthermore, HCV2–HCV4 proceeded with the dying process and increased gradually. We concluded that HCVs, which failed first in the high-frequency components and then in the low-frequency components, could provide physicians with earlier information to prevent the coming failure of circulatory system, and could reflect quantitatively pathological severity and predict patient outcome. The specific Fourier components in the pulse provide more physiological information than systolic and diastolic blood pressures.
Abstract We study the conditions for the existence of a sector with mass-degenerate supersymmetri... more Abstract We study the conditions for the existence of a sector with mass-degenerate supersymmetric partners in the presence of the spontaneous breaking of local supersymmetry, as the first step to characterize theories with residual global supersymmetry. The mass difference between fermions and scalars in each chiral multiplet is related to the Riemann curvatures tensor of the scalar field manifold, providing a necessary condition of geometrical nature on theories and chiral multiplets with degeneracy properties. From the study of the corresponding Riemann tensors, we determine the scalar curvature and the chiral multiplets consistent with mass degeneracy or all irreducible symmetric spaces. The solutions always correspond to a specific group coset space and are compared to the conditions for the existence of massless particles (Goldstone bosons, chiral fermions). We also discuss, on more general grounds, the possible choices of the superpotential and the appropriate holomorphic coordinates leading both to zero cosmological constant and mass degeneracy. Starting from their realization in models with flat potentials - in particular the SU( n ,1)/U( n ) ones - a general characterization is attempted. In this context, non-compact global symmetries of the whole Kahler potential emerge as a useful framework.
A 24-hour exchange market was created on the Web to trade political futures contracts using ficti... more A 24-hour exchange market was created on the Web to trade political futures contracts using fictitious money. In this online market, a political futures contract is a futures contract which matures on the election day with a liquidation price determined by the percentage of votes a candidate receives on the election day. Continuous double auctions were implemented as the system for order storage and price discovery. We drew market participants in the form of tournaments in which top traders won cash awards. Such a market was run, with about 400 registered traders, during the U.S. presidential election in November 2004 and Taiwan parliamentary election in December 2004. The experiments recorded transaction price, highest bid, lowest ask, and trading volume of each contract as a function of time. Despite the relatively small scale of the exchange, in terms of the number of participants and duration of the tournament, we report evidence for asymptotic power-law behaviors of the distributions of price returns, trading volumes, inter-transaction time intervals, and accumulated wealth that were found universal in real financial markets.
By using the Ward-Takahashi identities in the Landau gauge, we derive exact relations between par... more By using the Ward-Takahashi identities in the Landau gauge, we derive exact relations between particle masses and the vacuum expectation value of the Higgs field in the Abelian gauge field theory with a Higgs meson.
Various cross sections of jet and hadron productions through hard parton-parton scattering in pho... more Various cross sections of jet and hadron productions through hard parton-parton scattering in photon-photon collisions are calculated by quantumchromodynamics. Their characteristics are significantly different from those of e+e-and pp collisions.
International Journal of Modern Physics B, Sep 30, 2007
The Political Districting Problem is to partition a zone into several electoral districts subject... more The Political Districting Problem is to partition a zone into several electoral districts subject to some constraints such as contiguity, population equality, etc. In this paper, we apply statistical physics methods to Political Districting Problem. This political problem is mapped to a q-state Potts model system, and the political constraints are written in the form of an energy function with the interactions between sites or external fields acting on the system. Districting into q voter districts is equivalent to finding the ground state of this q-state Potts model. We illustrate this problem by districting Taipei city and compare it to a computer-generated artificial system.
Optical polarons in layered semiconductor structures are studied with the inclusion of many-body ... more Optical polarons in layered semiconductor structures are studied with the inclusion of many-body effects. The energy shift, the effective mass, and the lifetime of an optical polaron are calculated as functions of electron density and interlayer separation. The results indicate behavior qualitatively different from that of pure two-dimensional optical polarons.
Global symmetries of the D = 4 supergravity effective theory consistent with the compactification... more Global symmetries of the D = 4 supergravity effective theory consistent with the compactification of the superstring are shown to form an SU (1, 1) X U (1) group of transformations acting on the dilaton, axion and matter fields. These are exact invariances of the K~ihler potential if they are preserved by integration over Kaluza-Klein massive states. A key role is played by the cubic superpotential which is also essential in implementing flatness of the scalar potential, a vanishing cosmological constant and thus effective global supersymmetry in the matter sector, at the classical level. This is shown by an explicit computation of the scalar potential. If only an axion-like non-compact subgroup is left unbroken by the superpotential, the cosmological constant turns out to be negative in some cases.
Our previous study revealed that the coefficient of variation of harmonic magnitude (HCV) of radi... more Our previous study revealed that the coefficient of variation of harmonic magnitude (HCV) of radial arterial pulse was significantly raised before the death of cancer patients. In this study, we recorded the caudate arterial pulse of 24 Sprague-Dawley rats that had a fatal dose of urethane injected into their abdomens. Twenty rats were dead within 3 hours after the injection and four survived. We defined the last 100 minutes of each rat's life as the dying process. During the dying process, we found that both the systolic blood pressure and diastolic blood pressure dropped steeply during the last 5 minutes. However, all HCVs, except HCV1, climbed steeply before the last 5 minutes. The HCV1 of the dying rats was significantly higher than that of rats that survived, starting from the first minute (P<0.01). The HCV2 of the dying rats was significantly higher than that of the survived rats starting from the 52nd minute (P<0.05). The HCV3 and HCV4 of the dying rats were significantly higher than those of the survived rats until the 70th minute and the 80th minute, respectively (P<0.05). Furthermore, HCV2–HCV4 proceeded with the dying process and increased gradually. We concluded that HCVs, which failed first in the high-frequency components and then in the low-frequency components, could provide physicians with earlier information to prevent the coming failure of circulatory system, and could reflect quantitatively pathological severity and predict patient outcome. The specific Fourier components in the pulse provide more physiological information than systolic and diastolic blood pressures.
Abstract We study the conditions for the existence of a sector with mass-degenerate supersymmetri... more Abstract We study the conditions for the existence of a sector with mass-degenerate supersymmetric partners in the presence of the spontaneous breaking of local supersymmetry, as the first step to characterize theories with residual global supersymmetry. The mass difference between fermions and scalars in each chiral multiplet is related to the Riemann curvatures tensor of the scalar field manifold, providing a necessary condition of geometrical nature on theories and chiral multiplets with degeneracy properties. From the study of the corresponding Riemann tensors, we determine the scalar curvature and the chiral multiplets consistent with mass degeneracy or all irreducible symmetric spaces. The solutions always correspond to a specific group coset space and are compared to the conditions for the existence of massless particles (Goldstone bosons, chiral fermions). We also discuss, on more general grounds, the possible choices of the superpotential and the appropriate holomorphic coordinates leading both to zero cosmological constant and mass degeneracy. Starting from their realization in models with flat potentials - in particular the SU( n ,1)/U( n ) ones - a general characterization is attempted. In this context, non-compact global symmetries of the whole Kahler potential emerge as a useful framework.
A 24-hour exchange market was created on the Web to trade political futures contracts using ficti... more A 24-hour exchange market was created on the Web to trade political futures contracts using fictitious money. In this online market, a political futures contract is a futures contract which matures on the election day with a liquidation price determined by the percentage of votes a candidate receives on the election day. Continuous double auctions were implemented as the system for order storage and price discovery. We drew market participants in the form of tournaments in which top traders won cash awards. Such a market was run, with about 400 registered traders, during the U.S. presidential election in November 2004 and Taiwan parliamentary election in December 2004. The experiments recorded transaction price, highest bid, lowest ask, and trading volume of each contract as a function of time. Despite the relatively small scale of the exchange, in terms of the number of participants and duration of the tournament, we report evidence for asymptotic power-law behaviors of the distributions of price returns, trading volumes, inter-transaction time intervals, and accumulated wealth that were found universal in real financial markets.
By using the Ward-Takahashi identities in the Landau gauge, we derive exact relations between par... more By using the Ward-Takahashi identities in the Landau gauge, we derive exact relations between particle masses and the vacuum expectation value of the Higgs field in the Abelian gauge field theory with a Higgs meson.
Various cross sections of jet and hadron productions through hard parton-parton scattering in pho... more Various cross sections of jet and hadron productions through hard parton-parton scattering in photon-photon collisions are calculated by quantumchromodynamics. Their characteristics are significantly different from those of e+e-and pp collisions.
International Journal of Modern Physics B, Sep 30, 2007
The Political Districting Problem is to partition a zone into several electoral districts subject... more The Political Districting Problem is to partition a zone into several electoral districts subject to some constraints such as contiguity, population equality, etc. In this paper, we apply statistical physics methods to Political Districting Problem. This political problem is mapped to a q-state Potts model system, and the political constraints are written in the form of an energy function with the interactions between sites or external fields acting on the system. Districting into q voter districts is equivalent to finding the ground state of this q-state Potts model. We illustrate this problem by districting Taipei city and compare it to a computer-generated artificial system.
Optical polarons in layered semiconductor structures are studied with the inclusion of many-body ... more Optical polarons in layered semiconductor structures are studied with the inclusion of many-body effects. The energy shift, the effective mass, and the lifetime of an optical polaron are calculated as functions of electron density and interlayer separation. The results indicate behavior qualitatively different from that of pure two-dimensional optical polarons.
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Papers by Sai-ping Li