Study of f_0(980) and f_0(1500) from B_s \to f_0(980)\pi, f_0(1500)\pi Decays

In this paper, we analyze the scalar mesons $f_0(980)$ and $f_0(1500)$ from the decays $\bar B^0_s \to f_0(980)\pi^0, f_0(1500)\pi^0$ within Perturbative QCD approach. From the leading order calculations, we find that (a) in the allowed mixing angle ranges, the branching ratio of $\bar B^0_s\to f_0(980)\pi^0$ is about $(1.0\sim1.6)\times 10^{-7}$, which is smaller than that of $\bar B^0_s\to f_0(980)K^0$ (the difference is a few times even one order); (b) the decay $\bar B^0_s \to f_0(1500)\pi^0$ is better to distinguish between the lowest lying state or the first excited state for $f_0(1500)$, because the branching ratios for two scenarios have about one-order difference in most of the mixing angle ranges; and (c) the direct CP asymmetries of $\bar B^0_s \to f_0(1500)\pi^0$ for two scenarios also exists great difference. In scenario II, the variation range of the value ${\cal A} ^{dir}_{CP}(\bar B^0_s \to f_0(1500)\pi^0)$ according to the mixing angle is very small, except for the values corresponding to the mixing angles being near $90^\circ$ or $270^\circ$, while the variation range of ${\cal A} ^{dir}_{CP}(\bar B^0_s \to f_0(1500)\pi^0)$ in scenario I is very large. Compared with the future data for the decay $\bar B^0_s \to f_0(1500)\pi^0$, it is ease to determine the nature of the scalar meson $f_0(1500)$.Comment: 16 pages, 3 figures, Revte

The Proton Spin and Flavor Structure in the Chiral Quark Model

After a pedagogical review of the simple constituent quark model and deep inelastic sum rules, we describe how a quark sea as produced by the emission of internal Goldstone bosons by the valence quarks can account for the observed features of proton spin and flavor structures. Some issues concerning the strange quark content of the nucleon are also discussed.Comment: 59 pages with table of contents, Lecture delivered at the Schladming Winter School (March 1997), to be published by Springer-Verlag under the title "Computing Particle Properties" (eds. C. B. Lang and H. Gausterer

The evolution of cosmic string loops in Kerr-de Sitter spacetimes

The equation of cosmic string loops in Kerr-de Sitter spacetimes is derived. Having solved the equation numerically, we find that the loops can expand and exist except for too small ones.Comment: 8 page

Quantum Langevin theory of excess noise

In an earlier work [P. J. Bardroff and S. Stenholm], we have derived a fully quantum mechanical description of excess noise in strongly damped lasers. This theory is used here to derive the corresponding quantum Langevin equations. Taking the semi-classical limit of these we are able to regain the starting point of Siegman's treatment of excess noise [Phys. Rev. A 39, 1253 (1989)]. Our results essentially constitute a quantum derivation of his theory and allow some generalizations.Comment: 9 pages, 0 figures, revte

On supersymmetric contributions to the CP asymmetry of the B -> phi K_S

We analyse the CP asymmetry of the B -> phi K_S process in general supersymmetric models. In the framework of the mass insertion approximation, we derive model independent limits for the mixing CP asymmetry. We show that chromomagnetic type of operator may play an important role in accounting for the deviation of the mixing CP asymmetry between B -> phi K_S and B -> J/psi K_S processes observed by Belle and BaBar experiments. A possible correlation between the direct and mixing CP asymmetry is also discussed. Finally, we apply our result in minimal supergravity model and supersymmetric models with non-universal soft terms.Comment: 19 pages, 3 figure

B --> Phi K_S and Supersymmetry

The rare decay B --> Phi K_S is a well-known probe of physics beyond the Standard Model because it arises only through loop effects yet has the same time-dependent CP asymmetry as B --> Psi K_S. Motivated by recent data suggesting new physics in B --> Phi K_S, we look to supersymmetry for possible explanations, including contributions mediated by gluino loops and by Higgs bosons. Chirality-preserving LL and RR gluino contributions are generically small, unless gluinos and squarks masses are close to the current lower bounds. Higgs contributions are also too small to explain a large asymmetry if we impose the current upper limit on B(B_s --> mu mu). On the other hand, chirality-flipping LR and RL gluino contributions can provide sizable effects and while remaining consistent with related results in B --> Psi K_S, Delta M_s, B --> X_s gamma and other processes. We discuss how the LR and RL insertions can be distinguished using other observables, and we provide a string-based model and other estimates to show that the needed sizes of mass insertions are reasonable.Comment: 33 pages, 32 figures, Updated version for PRD. Includes discussions of other recent works on this topic. Added discussions & plots for gluino mass dependence and effects of theoretical uncertaintie

Phenomenological Consequences of Singlet Neutrinos

In this paper, we study the phenomenology of right-handed neutrino isosinglets. We consider the general situation where the neutrino masses are not necessarily given by $m_D^2/M$, where $m_D$ and $M$ are the Dirac and Majorana mass terms respectively. The consequent mixing between the light and heavy neutrinos is then not suppressed, and we treat it as an independent parameter in the analysis. It turns out that $\mu-e$ conversion is an important experiment in placing limits on the heavy mass scale ($M$) and the mixing. Mixings among light neutrinos are constrained by neutrinoless double beta decay, as well as by solar and atmospheric neutrino experiments. Detailed one-loop calculations for lepton number violating vertices are provided.Comment: Revtex file,TRI-PP-94-1,VPI-IHEP-94-1, 23 pages, a compressed for 8 figures is appende

Bumpy black holes from spontaneous Lorentz violation

We consider black holes in Lorentz violating theories of massive gravity. We argue that in these theories black hole solutions are no longer universal and exhibit a large number of hairs. If they exist, these hairs probe the singularity inside the black hole providing a window into quantum gravity. The existence of these hairs can be tested by future gravitational wave observatories. We generically expect that the effects we discuss will be larger for the more massive black holes. In the simplest models the strength of the hairs is controlled by the same parameter that sets the mass of the graviton (tensor modes). Then the upper limit on this mass coming from the inferred gravitational radiation emitted by binary pulsars implies that hairs are likely to be suppressed for almost the entire mass range of the super-massive black holes in the centers of galaxies.Comment: 40 pages, 4 figure

Charmless hadronic decays B→PP,PV,VVB \to PP, PV, VV and new physics effects in the general two-Higgs doublet models

Based on the low-energy effective Hamiltonian with the generalized factorization, we calculate the new physics contributions to the branching ratios of the two-body charmless hadronic decays of $B_u$ and $B_d$ mesons induced by the new gluonic and electroweak charged-Higgs penguin diagrams in the general two-Higgs doublet models (models I, II and III). Within the considered parameter space, we find that: (a) the new physics effects from new gluonic penguin diagrams strongly dominate over those from the new $\gamma$- and $Z^0$- penguin diagrams; (b) in models I and II, new physics contributions to most studied B meson decay channels are rather small in size: from -15% to 20%; (c) in model III, however, the new physics enhancements to the penguin-dominated decay modes can be significant, $\sim (30 -200)$, and therefore are measurable in forthcoming high precision B experiments; (d) the new physics enhancements to ratios {\cal B}(B \to K \etap) are significant in model III, $\sim (35 -70)$, and hence provide a simple and plausible new physics interpretation for the observed unexpectedly large B \to K \etap decay rates; (e) the theoretical predictions for ${\cal B}(B \to K^+ \pi)$ and ${\cal B}(B \to K^0 \pi^+)$ in model III are still consistent with the data within $2\sigma$ errors; (f) the significant new physics enhancements to the branching ratios of $B \to K^0 \pi^0, K^* \eta, K^{*+} \pi^-, K^+ \phi, K^{*0} \omega, K^{*+} \phi$ and $K^{*0} \phi$ decays are helpful to improve the agreement between the data and the theoretical predictions; (g) the theoretical predictions of ${\cal B}(B \to PP, PV, VV)$ in the 2HDM's are generally consistent with experimental measurements and upper limits ($90$)Comment: 55 pages, Latex file, 17 PS and EPS figures. With minor corrections, final version to be published in Phys.Rev. D. Repot-no: PKU-TH-2000-4

KK Parity in Warped Extra Dimension

We construct models with a Kaluza-Klein (KK) parity in a five- dimensional warped geometry, in an attempt to address the little hierarchy problem present in setups with bulk Standard Model fields. The lightest KK particle (LKP) is stable and can play the role of dark matter. We consider the possibilities of gluing two identical slices of 5D AdS in either the UV (IR-UV-IR model) or the IR region (UV-IR-UV model) and discuss the model-building issues as well as phenomenological properties in both cases. In particular, we find that the UV-IR-UV model is not gravitationally stable and that additional mechanisms might be required in the IR-UV-IR model in order to address flavor issues. Collider signals of the warped KK parity are different from either the conventional warped extra dimension without KK parity, in which the new particles are not necessarily pair-produced, or the KK parity in flat universal extra dimensions, where each KK level is nearly degenerate in mass. Dark matter and collider properties of a TeV mass KK Z gauge boson as the LKP are discussed.Comment: 35 pages, 11 figure