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Enhanced K(L) ---> Pi0 Nu Anti-Nu From Direct CP Violation in B ---> K Pi With Four Generations

Description: Recent CP violation results in B decays suggest that Z penguins may have large weak phase. This can be realized by the four generation (standard) model. Concurrently, B {yields} X{sub s}{ell}{sup +}{ell}{sup -} and B{sub s} mixing allow for sizable V*{sub t's}V{sub t'b} only if it is nearly imaginary. Such large effects in b {leftrightarrow} s transitions would affect s {leftrightarrow} d transitions, as kaon constraints would demand V{sub t'd} {ne} 0. Using {Lambda}(Z {yields} b{bar b}) to bound |V{sub t'b}|, they infer sizable |V{sub t's}| {le} |V{sub t'b}| {le} |V{sub us}|. Imposing {var_epsilon}{sub K}, K{sup +} {yields} {pi}{sup +}{nu}{bar {nu}} and {var_epsilon}'/{var_epsilon} constraints, they find V*{sub t'd} V{sub t's} {approx} few x 10{sup -4} with large phase, enhancing K{sub L} {yields} {pi}{sup 0} {nu}{bar {nu}} to 5 x 10{sup -10} or even higher. Interestingly, {Delta}m{sub B{sub d}} and sin 2{Phi}{sub B{sub d}} are not much affected, as |V*{sub t'd} V{sub t'b} << |V*{sub td} V{sub tb}| {approx} 0.01.
Date: September 2, 2005
Creator: Hou, Wei-Shu; /Taiwan, Natl. Taiwan U. /SLAC; Nagashima, Makiko; /Taiwan, Natl. Taiwan U.; Soddu, Andrea & /Taiwan, Natl. Taiwan U. /Weizmann Inst.
Partner: UNT Libraries Government Documents Department

Analysing the Effect on CMB in a Parity and Charge Parity Violating Varying Alpha Theory

Description: In this paper we study in detail the effect of our recently proposed model of parity and charge-parity (PCP) violating varying alpha on the Cosmic Microwave Background (CMB) photon passing through the intra galaxy-cluster medium (ICM). The ICM is well known to be composed of magnetized plasma. According to our model, the polarization and intensity of the CMB would be affected when traversing through the ICM due to non-trivial scalar photon interactions. We have calculated the evolution of such polarization and intensity collectively, known as the stokes parameters of the CMB photon during its journey through the ICM and tested our results against the Sunyaev-Zel'dovich (SZ) measurement on Coma galaxy cluster. Our model contains a PCP violating parameter, {beta}, and a scale of alpha variation {omega}. Using the derived constrained on the photon-to-scalar conversion probability, {bar P}{sub {gamma}{yields}{phi}}, for Coma cluster in ref.[34] we found a contour plot in the ({omega},{beta}) parameter plane. The {beta} = 0 line in this parameter space corresponds to well-studied Maxwell-dilaton type models which has lower bound on {omega} {approx}> 6.4 x 10{sup 9} GeV. In general, as the absolute value of {beta} increases, lower bound on {omega} also increases. Our model in general predicts the modification of the CMB polarization with a non-trivial dependence on the parity violating coupling parameter {beta}. However, it is unconstrained in this particular study. We show that this effect can in principle be detected in the future measurements on CMB polarization such that {beta} can also be constrained.
Date: September 14, 2012
Creator: Maity, Debaprasad; /NCTS, Taipei /Taiwan, Natl. Taiwan U.; Chen, Pisin & /NCTS, Taipei /Taiwan, Natl. Taiwan U. /KIPAC, Menlo Park /SLAC
Partner: UNT Libraries Government Documents Department

Cosmological Imprints of a Generalized Chaplygin Gas Model for the Early Universe

Description: We propose a phenomenological model for the early universe where there is a smooth transition between an early quintessence phase and a radiation-dominated era. The matter content is modeled by an appropriately modified Chaplygin gas for the early universe. We constrain the model observationally by mapping the primordial power spectrum of the scalar perturbations to the latest data of WMAP7. We compute as well the spectrum of the primordial gravitational waves as would be measured today. We show that the high frequencies region of the spectrum depends on the free parameter of the model and most importantly this region of the spectrum can be within the reach of future gravitational waves detectors.
Date: June 6, 2012
Creator: Bouhmadi-Lopez, Mariam; /Lisbon, CENTRA; Chen, Pisin; /Taiwan, Natl. Taiwan U. /KIPAC, Menlo Park /SLAC; Liu, Yen-Wei & /Taiwan, Natl. Taiwan U.
Partner: UNT Libraries Government Documents Department

Constraining PCP Violating Varying Alpha Theory through Laboratory Experiments

Description: In this report we have studied the implication of a parity and charge-parity (PCP) violating interaction in varying alpha theory. Due to this interaction, the state of photon polarization can change when it passes through a strong background magnetic field. We have calculated the optical rotation and ellipticity of the plane of polarization of an electromagnetic wave and tested our results against different laboratory experiments. Our model contains a PCP violating parameter {beta} and a scale of alpha variation {omega}. By analyzing the laboratory experimental data, we found the most stringent constraints on our model parameters to be 1 {le} {omega} {le} 10{sup 13} GeV{sup 2} and -0.5 {le} {beta} {le} 0.5. We also found that with the existing experimental input parameters it is very difficult to detect the ellipticity in the near future.
Date: June 6, 2012
Creator: Maity, Debaprasad; /NCTS, Taipei /Taiwan, Natl. Taiwan U.; Chen, Pisin & /NCTS, Taipei /Taiwan, Natl. Taiwan U. /KIPAC, Menlo Park /SLAC
Partner: UNT Libraries Government Documents Department

Stability of Horava-Lifshitz Black Holes in the Context of AdS/CFT

Description: The anti-de Sitter/conformal field theory (AdS/CFT) correspondence is a powerful tool that promises to provide new insights toward a full understanding of field theories under extreme conditions, including but not limited to quark-gluon plasma, Fermi liquid, and superconductor. In many such applications, one typically models the field theory with asymptotically AdS black holes. These black holes are subjected to stringy effects that might render them unstable. Horava-Lifshitz gravity, in which space and time undergo different transformations, has attracted attention due to its power-counting renormalizability. In terms of AdS/CFT correspondence, Horava-Lifshitz black holes might be useful to model holographic superconductors with Lifshitz scaling symmetry. It is thus interesting to study the stringy stability of Horava-Lifshitz black holes in the context of AdS/CFT. We find that uncharged topological black holes in {lambda} = 1 Horava-Lifshitz theory are nonperturbatively stable, unlike their counterparts in Einstein gravity, with the possible exceptions of negatively curved black holes with detailed balance parameter {epsilon} close to unity. Sufficiently charged flat black holes for {epsilon} close to unity, and sufficiently charged positively curved black holes with {epsilon} close to zero, are also unstable. The implication to the Horava-Lifshitz holographic superconductor is discussed.
Date: June 13, 2012
Creator: Ong, Yen Chin; /Taiwan, Natl. Taiwan U.; Chen, Pisin & /Taiwan, Natl. Taiwan U. /KIPAC, Menlo Park /SLAC
Partner: UNT Libraries Government Documents Department

Comments on 'Modeling Galaxy Halos Using Dark Matter with Pressure'

Description: We comment on the calculational mistake in the paper 'Modeling galaxy halos using dark matter with pressure' by Somnath Bharadwaj and Sayan Kar. The authors made a mistake while calculating the metric, which led to an overestimate of the deflection angle of light passing through the halos for -1 < w{sub r} < -0.5 and an underestimate of the deflection angle for -0.5 < w{sub r} < 0. In addition, the solution for w{sub r} > 0 should not exist. Although the Bharadwaj-Kar solution should be corrected, it appears that the characteristics of the deflection angle under the supposed nonconventional, nonideal fluid equation of state for the dark matter halo remain sensitive to the impact parameter and may be verifiable through observations.
Date: November 30, 2011
Creator: Su, Kung-Yi; /Taiwan, Natl. Taiwan U.; Chen, Pisin & /Taiwan, Natl. Taiwan U. /KIPAC, Menlo Park /SLAC
Partner: UNT Libraries Government Documents Department

A Possible Solution to the Smallness Problem of Dark Energy

Description: The smallness of the dark energy density has been recognized as the most crucial difficulty in understanding dark energy and also one of the most important questions in the new century. In a recent paper[1], we proposed a new dark energy model in which the smallness of the cosmological constant is naturally achieved by invoking the Casimir energy in a supersymmetry-breaking brane-world. In this paper we review the basic notions of this model. Various implications, perspectives, and subtleties of this model are briefly discussed.
Date: July 8, 2005
Creator: Chen, Pisin; /SLAC; Gu, Je-An & /Taiwan, Natl. Taiwan U.
Partner: UNT Libraries Government Documents Department

A Lower Bound on Neutrino Mass And Its Implication on the Z-Burst Scenario

Description: We show that the cascade limit on ultra high energy cosmic neutrino (UHEC/nu) flux imposes a lower bound on the neutrino mass provided that super-GZK events of ultra high energy cosmic rays (UHECRs) are produced from Z-bursts. Based on the data from HiRes and AGASA, the obtained neutrino mass lower bound violates its existing cosmological upper bound. We conclude that the Z-burst cannot be the dominant source for the observed super-GZK UHECR events. This is consistent with the recent ANITA-lite data.
Date: January 11, 2006
Creator: Lai, Kwang-Chang; /Taiwan, Natl. Taiwan U.; Chen, Pisin & /KIPAC, Menlo Park
Partner: UNT Libraries Government Documents Department

A New Type of Plasma Wakefield Accelerator Driven By Magnetowaves

Description: We present a new concept for a plasma wakefield accelerator driven by magnetowaves (MPWA). This concept was originally proposed as a viable mechanism for the 'cosmic accelerator' that would accelerate cosmic particles to ultra-high energies in the astrophysical setting. Unlike the more familiar plasma wakefield accelerator (PWFA) and the laser wakefield accelerator (LWFA) where the drivers, the charged-particle beam and the laser, are independently existing entities, MPWA invokes the high-frequency and high-speed whistler mode as the driver, which is a medium wave that cannot exist outside of the plasma. Aside from the difference in drivers, the underlying mechanism that excites the plasma wakefield via the ponderomotive potential is common. Our computer simulations show that under appropriate conditions, the plasma wakefield maintains very high coherence and can sustain high-gradient acceleration over many plasma wavelengths. We suggest that in addition to its celestial application, the MPWA concept can also be of terrestrial utility. A proof-of-principle experiment on MPWA would benefit both terrestrial and celestial accelerator concepts.
Date: September 12, 2011
Creator: Chen, Pisin; /KIPAC, Menlo Park /Taiwan, Natl. Taiwan U.; Chang, Feng-Yin; Lin, Guey-Lin; /Taiwan, Natl. Chiao Tung U. /Taiwan, Natl. Taiwan U.; Noble, Robert J. et al.
Partner: UNT Libraries Government Documents Department