3,563 research outputs found

    Status of the KTeV Experiment at Fermilab

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    The KTeV experiment is a fixed target experiment at Fermilab. Its primary goal is the search for direct CP violation in the decay of neutral kaons. Its current status and some preliminary results will be discussed.Comment: 5 pages Latex, 4 figures; to be published in the proceedings of the XVI International Workshop on Weak Interactions and Neutrinos, WIN '97, Capri, Italy, June 22-28, 199

    Angular Distribution and CP Asymmetries in the Decays B->K^-pi^+e^-e^+ and B->pi^-pi^+e^-e^+

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    The short-distance Hamiltonian describing b->s(d)e^-e^+ in the standard model is used to obtain the decay spectrum of \bar{B}->K^-pi^+e^-e^+ and \bar{B}->pi^-pi^+e^-e^+, assuming the Kpi and pipi systems to be the decay products of K^* and rho respectively. Specific features calculated are (i) angular distribution of K^- (or pi^-) in the K^-pi^+ (or pi^-pi^+) centre-of-mass (c.m.) frame; (ii) angular distribution of e^- in the e^-e^+ c.m. frame; and (iii) the correlation between the meson and lepton planes. We also derive CP-violating observables obtained by combining the above decays with the conjugate processes B->K^+pi^-e^-e^+ and B->pi^-pi^+e^-e^+.Comment: 19 pages, REVTeX, no figures. Equations (2.19a), (2.19b), (5.5)-(5.7) have been corrected; all results remain unchanged. These changes will appear in an Erratum submitted to Phys. Rev.

    CP Violation and Arrows of Time Evolution of a Neutral KK or BB Meson from an Incoherent to a Coherent State

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    We study the evolution of a neutral KK meson prepared as an incoherent equal mixture of K0K^0 and K0ˉ\bar{K^0}. Denoting the density matrix by \rho(t) = {1/2} N(t) [\1 + \vec{\zeta}(t) \cdot \vec{\sigma} ] , the norm of the state N(t)N(t) is found to decrease monotonically from one to zero, while the magnitude of the Stokes vector ζ(t)|\vec{\zeta}(t)| increases monotonically from zero to one. This property qualifies these observables as arrows of time. Requiring monotonic behaviour of N(t)N(t) for arbitrary values of γL,γS\gamma_L, \gamma_S and Δm\Delta m yields a bound on the CP-violating overlap δ=KLKS\delta = \braket{K_L}{K_S}, which is similar to, but weaker than, the known unitarity bound. A similar requirement on ζ(t)|\vec{\zeta}(t)| yields a new bound, δ2<1/2(ΔγΔm)sinh(3π4ΔγΔm)\delta^2 < {1/2} (\frac{\Delta \gamma}{\Delta m}) \sinh (\frac{3\pi}{4} \frac{\Delta \gamma}{\Delta m}) which is particularly effective in limiting the CP-violating overlap in the B0B^0-B0ˉ\bar{B^0} system. We obtain the Stokes parameter ζ3(t)\zeta_3(t) which shows how the average strangeness of the beam evolves from zero to δ\delta. The evolution of the Stokes vector from ζ=0|\vec{\zeta}| = 0 to ζ=1|\vec{\zeta}| = 1 has a resemblance to an order parameter of a system undergoing spontaneous symmetry breaking.Comment: 13 pages, 6 figures. Inserted conon "." in title; minor change in text. To appear in Physical review

    Viscosity of Cesium Chloride in Ethylene Glycol

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    36-3

    Apparent Molal Volumes of Tetraethylammonium Halides in Ethylene Glycol

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    162-16

    Baryon Magnetic Moments and Proton Spin: A Model with Collective Quark Rotation

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    We analyse the baryon magnetic moments in a model that relates them to the parton spins Δu\Delta u, Δd\Delta d, Δs\Delta s, and includes a contribution from orbital angular momentum. The specific assumption is the existence of a 3-quark correlation (such as a flux string) that rotates with angular momentum Lz\langle L_z \rangle around the proton spin axis. A fit to the baryon magnetic moments, constrained by the measured values of the axial vector coupling constants a(3)=F+Da^{(3)}=F+D, a(8)=3FDa^{(8)}=3F-D, yields Sz=0.08±0.13\langle S_z \rangle = 0.08 \pm 0.13, Lz=0.39±0.09\langle L_z \rangle = 0.39 \pm 0.09, where the error is a theoretical estimate. A second fit, under slightly different assumptions, gives Lz=0.37±0.09\langle L_z \rangle = 0.37 \pm 0.09, with no constraint on Sz\langle S_z \rangle. The model provides a consistent description of axial vector couplings, magnetic moments and the quark polarization Sz\langle S_z \rangle measured in deep inelastic scattering. The fits suggest that a significant part of the angular momentum of the proton may reside in a collective rotation of the constituent quarks.Comment: 16 pages, 3 ps-figures, uses RevTeX. Abstract, Sec. II, III and IV have been expande
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