CP Violation in Top Physics

CP violation in top physics is reviewed. The Standard Model has negligible effects, consequently CP violation searches involving the top quark may constitute the best way to look for physics beyond the Standard Model. Non-standard sources of CP violation due to an extended Higgs sector with and without natural flavor conservation and supersymmetric theories are discussed. Experimental feasibility of detecting CP violation effects in top quark production and decays in high energy e+ e-, gamma-gamma, mu+ mu-, pp and p-bar p colliders are surveyed. Searches for the electric, electro-weak and the chromo-electric dipole moments of the top quark in e+ e- -> t-bar t and in p p -> t-bar t X are descibed. In addition, other mechanisms that appear promising for experiments, e.g., tree-level CP violation in e+ e- -> t-bar t h, t-bar t Z, t-bar t nu_e-bar nu_e and in the top decay t -> b tau nu_tau and CP violation driven by s-channel Higgs exchanges in p p, gamma gamma, mu+ mu- -> t-bar t etc., are also discussed.Comment: 253 pages, 70 figures, A 2-up version of this postscript file may be obtained at http://thy.phy.bnl.gov/~soni/topreview.htm

CP Violation In Single Top Production And Decay Via p p-bar -> t b-bar +X -> W^+ b b-bar +X Within The MSSM: A Possible Application For Measuring \arg(A_t) At Hadron Colliders

CP-nonconserving effects in the reaction p p-bar -> t b-bar +X -> W^+ b b-bar +X, driven by the supersymmetric CP-odd phase of the stop trilinear soft breaking term, \arg(A_t), are studied. We discuss the CP-nonconserving effects in both production and the associated decay amplitudes of the top. We find that, within a plausible low energy scenario of the MSSM and keeping the neutron electric dipole moment below its current limit, a CP-violating cross-section asymmetry as large as 2-3% can arise if some of the parameters lie in a favorable range. A partial rate asymmetry originating only in the top decay t -> W^+ b is found to be, in general, below the 0.1% level which is somewhat smaller than previous claims. For a low \tan\beta of order one the decay asymmetry can reach at the most ~0.3%. This (few) percent level overall CP-violating signal in p p-bar -> t b-bar +X -> W^+ b b-bar +X might be within the reach of the future 2(4) TeV pp-bar Tevatron collider that may be able to produce ~10000(~30000) such tb-bar events with an integrated luminosity of 30 fb^{-1}. In particular, it may be used to place an upper bound on \arg(A_t) if indeed \arg(\mu) -> 0, as implied from the present experimental limit on the neutron electric dipole moment. The partial rate asymmetry in the top decay (~few \times 10^{-3}) may also be within the reach of the LHC with ~10^7 pairs of tt-bar produced, provided detector systematics are sufficiently small. We also show that if the GUT-scale universality of the soft breaking trilinear $A$ terms is relaxed, then the phases associated with \arg A_u and \arg A_d can take values up to ~few \times 10^{-1} even with squarks and gluino masses of several hundred GeV's without contradicting the experimental limit on the neutron electric dipole moment.Comment: 39 pages, plain latex, 20 figures embadded in the text using epsfi

Light Rays of New Physics: CP Violation in B -> Xs gamma Decays

The observation of a sizable CP asymmetry in the inclusive decays B -> Xs gamma would be a clean signal of New Physics. In the Standard Model, this asymmetry is below 1 % in magnitude. In extensions of the Standard Model with new CP-violating couplings, large asymmetries are possible without conflicting with the experimental value of the B -> Xs gamma branching ratio. In particular, large asymmetries arise naturally in models with enhanced chromo-magnetic dipole transitions. Some generic examples of such models are explored and their implications for the semileptonic branching ratio and charm yield in B decays discussed.Comment: 6 pages, 2 figures, uses ltwol2e.sty (included); to appear in the Proceedings of the QCD 98 Euroconference (Montpellier) and of the 29th International Conference on High Energy Physics (Vancouver

Flavor Physics and the CKM Matrix: An Overview

I review the current status of our knowledge of CP violation and flavor physics. I discuss where one should look for future improvements, and outline the experimental and theoretical priorities of the field.Comment: 11 pages. Presentation at the Fifth KEK Topical Conference, "Frontiers in Flavor Physics", November 20-22, 2001. References adde

Potential Models for Radiative Rare B Decays

We compute the branching ratios for the radiative rare decays of B into K-Meson states and compare them to the experimentally determined branching ratio for inclusive decay b -> s gamma using non relativistic quark model, and form factor definitions consistent with HQET covariant trace formalism. Such calculations necessarily involve a potential model. In order to test the sensitivity of calculations to potential models we have used three different potentials, namely linear potential, screening confining potential and heavy quark potential as it stands in QCD.We find the branching ratios relative to the inclusive b ->s gamma decay to be (16.07\pm 5.2)% for B -> K^* (892)gamma and (7.25\pm 3.2)% for B -> K_2^* (1430)gamma for linear potential. In the case of the screening confining potential these values are (19.75\pm 5.3)% and (4.74\pm 1.2)% while those for the heavy quark potential are (11.18\pm 4.6)% and (5.09\pm 2.7)% respectively. All these values are consistent with the corresponding present CLEO experimental values: (16.25\pm 1.21)% and (5.93\pm 0.46)%.Comment: RevTeX, 6 pages, 1 eps figur

Genomic organization and expression profile of the mucin-associated surface protein (masp) family of the human pathogen Trypanosoma cruzi

A novel large multigene family was recently identified in the human pathogen Trypanosoma cruzi, causative agent of Chagas disease, and corresponds to ∼6% of the parasite diploid genome. The predicted gene products, mucin-associated surface proteins (MASPs), are characterized by highly conserved N- and C-terminal domains and a strikingly variable and repetitive central region. We report here an analysis of the genomic organization and expression profile of masp genes. Masps are not randomly distributed throughout the genome but instead are clustered with genes encoding mucin and other surface protein families. Masp transcripts vary in size, are preferentially expressed during the trypomastigote stage and contain highly conserved 5′ and 3′ untranslated regions. A sequence analysis of a trypomastigote cDNA library reveals the expression of multiple masp variants with a bias towards a particular masp subgroup. Immunofluorescence assays using antibodies generated against a MASP peptide reveals that the expression of particular MASPs at the cell membrane is limited to subsets of the parasite population. Western blots of phosphatidylinositol-specific phospholipase C (PI-PLC)-treated parasites suggest that MASP may be GPI-anchored and shed into the medium culture, thus contributing to the large repertoire of parasite polypeptides that are exposed to the host immune system

CP asymmetries in B0 decays in the left-right model

We study time dependent CP asymmetries in B^0_{d,s} decays in the left-right model with spontaneous breakdown of CP. Due to the new contributions to B^0-\bar B^0 mixing the CP asymmetries can be substantially modified. Moreover, there can be significant new contributions to the $B$-meson decay amplitudes from the magnetic penguins. Most promising for detection of the new physics in the planned $B$ factories is that the CP asymmetries in the decays B--> J/\psi K_S and B--> \phi K_S which are supposed to be equal in the standard model can differ significantly in this class of models independently of the results in the measurements of B--> X_s \gamma.Comment: Revised version, to appear in PR

Direct CP Violation in B -> X_s gamma Decays as a Signature of New Physics

We argue that the observation of a sizable direct CP asymmetry A_{CP} in the inclusive decays B -> X_s gamma would be a clean signal of New Physics. In the Standard Model, A_{CP} can be calculated reliably and is found to be below 1% in magnitude. In extensions of the Standard Model with new CP-violating couplings, large CP asymmetries are possible without conflicting with the experimental value of the branching ratio for the decays B -> X_s gamma. In particular, large asymmetries arise naturally in models with enhanced chromo-magnetic dipole operators. Some generic examples of such models are explored and their implications for the semileptonic branching ratio and charm yield in B decays discussed.Comment: several references added and some numerical results updated to include QED corrections (version to appear in Physical Review D

Kinetoplastids:related protozoan pathogens, different diseases

Kinetoplastids are a group of flagellated protozoans that include the species Trypanosoma and Leishmania, which are human pathogens with devastating health and economic effects. The sequencing of the genomes of some of these species has highlighted their genetic relatedness and underlined differences in the diseases that they cause. As we discuss in this Review, steady progress using a combination of molecular, genetic, immunologic, and clinical approaches has substantially increased understanding of these pathogens and important aspects of the diseases that they cause. Consequently, the paths for developing additional measures to control these “neglected diseases” are becoming increasingly clear, and we believe that the opportunities for developing the drugs, diagnostics, vaccines, and other tools necessary to expand the armamentarium to combat these diseases have never been better

Lattice Matrix Elements and CP Violation in B and K Physics: Status and Outlook

Status of lattice calculations of hadron matrix elements along with CP violation in B and in K systems is reviewed. Lattice has provided useful input which, in conjunction with experimenatl data, leads to the conclusion that CP-odd phase in the CKM matrix plays the dominant role in the observed asymmetry in $B \to \psi K_s$. It is now quite likely that any beyond the SM, CP-odd, phase will cause only small deviations in B-physics. Search for the effects of the new phase(s) will consequently require very large data samples as well as very precise theoretical predictions. Clean determination of {\it all} the angles of the unitarity triangle therefore becomes essential. In this regard $B \to K D^0$ processes play a unique role. Regarding K-decays, remarkable progress made by theory with regard to maintenance of chiral symmetry on the lattice is briefly discussed. First application already provide quantitaive information on $B_K$ and the $\Delta I=1/2$ rule. The enhancement in $Re A_0$ appears to arise solely from tree operators, esp. $Q_2$; penguin contribution to $Re A_0$ appears to be very small. However, improved calculations are necessary for \epsilon^'/epsilon as there the contributions of QCD penguins and electroweak penguins largely seem to cancel. There are good reasons, though, to believe that these cancellations will not survive improvements that are now underway. Importance of determining the unitarity triangle purely from K-decays is also emphasized.Comment: Invited talk at the 9th International Symposium on Particles, Strings and Cosmology (PASCOS 03), Mumbai (Bombay) India,3-8 Jan 200