Status on the Searches of Neutrino Magnetic Moment at the Kuo-Sheng Power Reactor

The TEXONO collaboration has been built up among scientists from Taiwan and China to pursue an experimental program in neutrino and astro-particle physics. The flagship efforts have been the study of low energy neutrino physics at the Kuo-Sheng Power Reactor Plant in Taiwan. The Reactor Laboratory is equipped with flexibly-designed shieldings, cosmic veto systems, electronics and data acquisition systems which can function with different detector schemes. Data are taken during the Reactor Period June-01 till April-02 with a high purity germanium detector and 46 kg of CsI(Tl) crystal scintillator array operating in parallel. A threshold of 5 keV has been achieved for the germanium detector, and the background level comparable to those of Dark Matter experiments underground is achieved. Based on 62/46 days of analyzed Reactor ON/OFF data, a preliminary result of \rm{(\munue / 10^{-10} \mub)^2 = - 1.1 \pm 2.5} can be derived for neutrino magnetic moment \munue. Sensitivity region on neutrino radiative decay lifetime is inferred. The complete data set would include 180/60 days of ON/OFF data.Comment: Contributed Paper to the International Conference on High Energy Physics, 200

High fidelity ac gate operations of the quantum dot hybrid qubit

Semiconductor quantum dots in silicon are promising qubits because of long spin coherence times and their potential for scalability. However, such qubits with complete electrical control and fidelities above the threshold for quantum error correction have not yet been achieved. We show theoretically that the threshold fidelity can be achieved with ac gate operation of the quantum dot hybrid qubit. Formed by three electrons in a double dot, this qubit is electrically controlled, does not require magnetic fields, and runs at GHz gate speeds. We analyze the decoherence caused by 1/f charge noise in this qubit, find the parameter regime for tunnel couplings and detuning that minimize the charge noise dependence in the qubit frequency, and determine the optimal working points for ac gate operations that drive the detuning and tunnel coupling

The Equilibration of a Parton Plasma Created In Relativistic Heavy Ion Collisions

We study the equilibration of a parton plasma in terms of its parton compositions and its state of thermalization. In studying the evolution of the plasma, one has to assume a small value of the strong coupling constant. This value is by no means fixed. By varying this only parameter in our calculation, we show the dependence of equilibration on its magnitude. It is shown that both kinetic and parton equilibration are faster with increasing coupling but the plasma cools much more rapidly resulting in shortened lifetime. The degree of equilibration improves significantly for quarks and antiquarks but not so for gluons and the total generated entropy is reduced. With a coupling depending on the average parton energy, there is additional acceleration in the equilibration during the evolution.Comment: 4 pages with 4 embedded PS figures, Talk presented at the 3rd International Conference on the Physics and Astrophysics of the Quark-Gluon Plasma, Jaipur, India, March 199

Out-of-Equilibrium Collinear Enhanced Equilibration in the Bottom-Up Thermalization Scenario in Heavy Ion Collisions

Experimental measurement of the elliptic flow parameter $v_2$ and hydrodynamic model together showed that thermalization in the central region at the Relativistic Heavy Ion Collider to be perplexingly fast. This is a mystery in itself since none of the numerical perturbative QCD models are able to achieve such a feat. By exploiting a theoretical oversight on collinear processes in an out-of-equilibrium system it is argued that, in the bottom-up thermalization scenario, equilibration can proceed at a higher rate than what is expected in the conventional perturbative QCD picture.Comment: 7 embedded EPS figure

What exactly is a Skyrmion?

Skyrmions are well known to be baryons because their topological charge has been positively identified with the baryon number. Beyond that their identity has never been clear. In view of the possibility of skyrmion production through Disoriented Chiral Condensates in heavy ion collisions, the exact identity of the skyrmion must be resolved before they can be identified in experiments. It is shown that skyrmions are not individual baryons but coherent states of known baryons and higher resonances on a compact manifold associated with the spin and flavor symmetry group. An outline of how to calculate exactly the probability amplitudes of the superposition of physical baryon and excited baryon states that make up the skyrmion is given.Comment: 4 pages, no figure, corrected some reference

Equivalence of Classical Skyrmions and Coherent States of Baryons I. Constrained Quantization on the SU(2) and SO(3) manifolds

In the Skyrme model, the Lagrangian can be quantized in several ways using the collective coordinate approach. Not all of which produce quantum states that can be interpreted as physical particles. For example the SU(2) collective coordinate approach produces both integral and half-integral spin and isospin states. Only half of these are the physical baryons. Less well known is the fact that it is equally possible to quantize the system using the SO(3) collective coordinates. This produces only unphysical integral spin and isospin states. To fulfill the goal of being able to express a classical skyrmion as a coherent state of baryons directly in terms of the baryon states, surprisingly a combination of both collective coordinate approaches is required. To prepare for the subsequent application to skyrmion formation through disoriented chiral condensates in heavy ion collisions, the Skyrme model is rigorously quantized using the Dirac prescription for constrained systems. This is shown for both the SU(2) as well as the SO(3) collective coordinate approach.Comment: revtex4, 16 pages, no figure

Equilibration and Particle Production in an Increasingly Strongly Interacting Parton Plasma

We report on a new equilibration scenario in relativistic heavy ion collisions, the scenario of the Increasingly Strongly Interacting Parton Plasma, and the effects of this scenario on equilibration and open charm, photon and dilepton production. The parton plasma is shown to be a very special kind of many-body system, which contains new physics concerning the approach towards equilibrium. This is likely to be unique to the parton plasma.Comment: 5 embedded EPS figures, espcrc1 style, talk presented at Quark Matter'97, December 97, Tsukuba, Japan, to appear in the proceeding

Equilibration And Out-Of-Equilibrium Effect In Relativistic Heavy Ion Collisions

The approach of a parton plasma at future heavy ion colliders towards kinetic and chemical equilibrium is considered. A plasma with a self-consistent evolving parton-parton interaction strength is shown to equilibrate better and faster than the usual but inconsistent one with a fixed strength. We explain why as a consequence of this, a parton plasma is a unique kind of many-body system. Because our time evolution scheme does not require the plasma to be in either kind of equilibrium from the outset, out-of-equilibrium effect on particle productions can be revealed. We show this on photon production and discuss the implications on photon as a signal to detect the quark-gluon plasma.Comment: use sprocl.sty, 6 EPS figures, talk presented at the XXVIII International Symposium on Multiparticle Dynamics, Delphi, Greece, Sept 98, to appear in the proceeding

Equivalence of Classical Skyrmions and Coherent States of Baryons II. Baryonic Coherent State Construction on Compact Manifolds

In connection with the possibility of skyrmion production from small domain disoriented chiral condensates formation from heavy ion collisions, the direct relation of a classical skyrmion to baryon states is examined. It is argued that a skyrmion is a coherent state of baryons. The collective coordinate approach of quantization means that the physical baryon states exist not in flat space but on a compact manifold. This requires the construction of coherent states in such a curve space. Using the techniques associated with the Segal-Bargmann transform also known as the coherent state transform used for example in the study of the classical limit of quantum gravity, such states can be constructed in the context of the Skyrme model. They are made up directly of baryon states on S^3 but with quantum operators on the SO(3) manifold. In terms of wavefunctions, they are a superposition of the analytic baryon wavefunctions of Adkins, Nappi and Witten. The distribution of the baryon states in terms of the relative probabilities of the baryons inside a skyrmion can therefore be determined.Comment: revtex4, 21 pages + 2 figure

Color Screening Effects on Hadronization in Relativistic Heavy Ion Collisions

The effects of color screening on the hadronization of a parton plasma into a hadron gas are examined at the energies of the relativistic heavy ion collider. It is found to have the tendency to prevent hadronization and therefore delaying the conversion of the partons into a hadron gas. Because of the continual expansion, the resulting hadron gas number densities are lower when screening is included. This should reduce the hadronic noise to genuine signals of the quark-gluon plasma. In this sense, color screening is favorable and should be included in numerical models. In any case, we advocate that numerical models should allow the confining forces and color screening to act on each other so as to undergo the phase transition in a natural way. Hadronization is also shown to seriously disrupt parton equilibration and is yet another reason why full parton chemical equilibration should not be expected.Comment: 8 embedded EPS figures, revtex style, 13 pages, Phys. Rev. C insisted on title chang