SUSY Contributions to RbR_b and Top Decay

I report on a systematic analysis of the MSSM parameter space to obtain the best SUSY solution to the $R_b$ anomaly within the constraint of top quark decay. Phenomenological implications for top decay and direct stop production at the Tevatron collider are discussed.Comment: Latex file (3 pages)+ 2 ps files containing figures. Invited talk at SUSY96, Maryland, May 199

Distinguishing multi-partite states by local measurements

We analyze the distinguishability norm on the states of a multi-partite system, defined by local measurements. Concretely, we show that the norm associated to a tensor product of sufficiently symmetric measurements is essentially equivalent to a multi-partite generalisation of the non-commutative 2-norm (aka Hilbert-Schmidt norm): in comparing the two, the constants of domination depend only on the number of parties but not on the Hilbert spaces dimensions. We discuss implications of this result on the corresponding norms for the class of all measurements implementable by local operations and classical communication (LOCC), and in particular on the leading order optimality of multi-party data hiding schemes.Comment: 18 pages, 6 figures, 1 unreferenced referenc

Constraints on the Charged Higgs Sector from the Tevatron Collider Data on Top Quark Decay

The top quark data in the lepton plus $\tau$ channel offers a viable probe for the charged Higgs boson signal. We analyse the recent Tevatron collider data in this channel to obtain a significant limit on the $H^\pm$ mass in the large $\tan\beta$ region.Comment: 8 pages, LaTeX file; 2 figures included (PS files

An absolute polarimeter for high energy protons

A study of the spin asymmetries for polarized elastic proton proton collisions in the electromagnetic hadronic interference (CNI) region of momentum transfer provides a method of self calibration of proton polarization. The method can be extended to non-identical spin half scattering so that, in principle, the polarization of a proton may be obtained through an analysis of its elastic collision with a different polarized particle, helium 3 for instance. Sufficiently large CNI spin asymmetries provide enough information to facilitate the evaluation of nearly all the helicity amplitudes at small t as well as the polarization of both initial spin half fermions. Thus it can serve equally well as a polarimeter for helium 3

Disorder induced critical phenomena in magnetically glassy Cu-Al-Mn alloys

Measurements of magnetic hysteresis loops in Cu-Al-Mn alloys of different Mn content at low temperatures are presented. The loops are smooth and continuous above a certain temperature, but exhibit a magnetization discontinuity below that temperature. Scaling analysis suggest that this system displays a disorder induced phase transition line. Measurements allow to determine the critical exponents $\beta=0.03\pm 0.01$ and $\beta \delta = 0.4 \pm 0.1$ in agreement with those reported recently [Berger et al., Phys. Rev. Lett. {\bf 85}, 4176 (2000)]Comment: 4 pages, 5 figure

On Coloring Resilient Graphs

We introduce a new notion of resilience for constraint satisfaction problems, with the goal of more precisely determining the boundary between NP-hardness and the existence of efficient algorithms for resilient instances. In particular, we study $r$-resiliently $k$-colorable graphs, which are those $k$-colorable graphs that remain $k$-colorable even after the addition of any $r$ new edges. We prove lower bounds on the NP-hardness of coloring resiliently colorable graphs, and provide an algorithm that colors sufficiently resilient graphs. We also analyze the corresponding notion of resilience for $k$-SAT. This notion of resilience suggests an array of open questions for graph coloring and other combinatorial problems.Comment: Appearing in MFCS 201

Restenosis, reocclusion and adverse cardiovascular events after successful balloon angioplasty of occluded versus nonoccluded coronary arteries: Results from the multicenter american research trial with cilazapril after angioplasty to prevent transluminal coronary obstruction and restenosis (MARCATOR)

OBJECTIVES: This study sought to compare the frequency of restenosis, reocclusion and adverse cardiovascular events after angioplasty of occluded versus nonoccluded coronary arteries. BACKGROUND: Angioplasty of chronically occluded coronary arteries is believed to be associated with a higher frequency of restenosis and reocclusion than angioplasty of subtotal stenoses. Whether this leads to adverse cardiovascular events is unknown. METHODS: The Multicenter American Research Trial With Cilazapril After Angioplasty to Prevent Restenosis (MARCATOR) was a placebo-controlled trial with angiographic follow-up to determine the effect of the angiotensin-converting enzyme inhibitor cilazapril on the frequency of restenosis. In this trial, restenosis was defined as 1) angiographic reduction of minimal lumen diameter > or = 0.72 mm between angioplasty and the follow-up visit; and 2) > 50% diameter stenosis on the follow-up angiogram. We identified

Transport Properties through Double Barrier Structure in Graphene

The mode-dependent transmission of relativistic ballistic massless Dirac fermion through a graphene based double barrier structure is being investigated for various barrier parameters. We compare our results with already published work and point out the relevance of these findings to a systematic study of the transport properties in double barrier structures. An interesting situation arises when we set the potential in the leads to zero, then our 2D problem reduces effectively to a 1D massive Dirac equation with an effective mass proportional to the quantized wave number along the transverse direction. Furthermore we have shown that the minimal conductivity and maximal Fano factor remain insensitive to the ratio between the two potentials V_2/V_1=\alpha.Comment: 18 pages, 12 figures, clarifications and reference added, misprints corrected. Version to appear in JLT

Fragmentation contribution to quarkonium production in hadron collision

We compute the contributions due to gluon and heavy-quark fragmentation to quarkonium production at large transverse momentum in $\bar p p$ and $p p$ collisions. For inclusive $J/\psi$ production, there is a large contribution from the $g \rightarrow \chi_c$ fragmentation. At large $p_T$, this is comparable to the conventional charmonium model prediction via gluon fusion at the ISR and dominates over the latter at the Tevatron energy. This may help to explain, at least partly, the large $J/\psi$ production cross-section recently observed by the CDF experiment. However, the fragmentation contribution to $\psi^{\prime}$ production is not large enough to explain the corresponding CDF data. We also present the results for $\Upsilon$ production at ISR and Tevatron energies.Comment: 9 pages + 4 figures (available upon request), Latex File, CERN-TH.7329/94, TIFR/TH/94-2

A possible resolution of the CDF psi^prime anomaly

We consider the contribution of radially excited 2^3P_{1,2} states to psi^prime production at the Tevatron energy. Production of these states via the conventional gluon fusion mechanism and via gluon and charm quark fragmentation processes is considered. We find that it is possible to account for the data on psi^prime production from the CDF experiment, by taking into account the decays of these 2^3P_{1,2} states into psi^prime.Comment: 8 pages + 1 figure (available upon request), CERN-TH.7434/9