122717656
Renormalization in indefinite metric theories
We consider the Lee model,V ⇆ N+θ, and a two neutral scalar meson model with indefinite metrics. It is shown that in general the coupling will cause positive definite bare states to become negative length dressed states through renormalization effects. This can render the theory unphysical depending upon the auxiliary conditions imposed with the indefinite metric.
10472717
Chiral multiplets of heavy-light mesons
The recent discovery of a narrow resonance in ${D}_{s}{\ensuremath{\pi}}^{0}$ by the BaBar Collaboration is consistent with the interpretation of a heavy ${J}^{P}{(0}^{+}{,1}^{+})$ spin multiplet. This system is the parity partner of the ground state ${(0}^{\ensuremath{-}}{,1}^{\ensuremath{-}})$ multiplet, which we argue is required in the implementation of ${\mathrm{SU}(3)}_{L}\ifmmode\times\else\texttimes\fi{}{\mathrm{SU}(3)}_{R}$ chiral symmetry in heavy-light meson systems. The ${(0}^{+}{,1}^{+})\ensuremath{\rightarrow}{(0}^{\ensuremath{-}}{,1}^{\ensuremath{-}})+\ensuremath{\pi}$ transition couplings satisfy a Goldberger-Treiman relation, ${g}_{\ensuremath{\pi}}=\ensuremath{\Delta}{M/f}_{\ensuremath{\pi}},$ where $\ensuremath{\Delta}M$ is the mass gap. The BaBar resonance fits the ${0}^{+}$ state, with a kinematically blocked principal decay mode to $D+K.$ The allowed ${D}_{s}+\ensuremath{\pi},$ ${D}_{s}+2\ensuremath{\pi},$ and electromagnetic transitions are computed from the full chiral theory and found to be suppressed, consistent with the narrowness of the state. This state establishes the chiral mass difference for all such heavy-quark chiral multiplets, and precise predictions exist for the analogous ${B}_{s}$ and strange doubly heavy baryon states.
11755173
Cosmology with ultralight pseudo Nambu-Goldstone bosons.
We explore the cosmological implications of an ultralight pseudo Nambu-Goldstone boson. With global spontaneous symmetry breaking scale $f\ensuremath{\simeq}{10}^{18}\mathrm{GeV}$ and explicit breaking scale comparable to Mikheyev-Smirnov-Wolfenstein neutrino masses, $M\ensuremath{\sim}{10}^{\ensuremath{-}3}\mathrm{eV}$, such a field, which acquires a mass ${m}_{\ensuremath{\varphi}}\ensuremath{\sim}{M}^{2}/f\ensuremath{\sim}{H}_{0}$, would currently dominate the energy density of the Universe. The field acts as an effective cosmological constant before relaxing into a condensate of nonrelativistic bosons. Such a model can reconcile dynamical estimates of the density parameter, ${\ensuremath{\Omega}}_{m}\ensuremath{\sim}0.2$, with a spatially flat universe, yielding ${H}_{0}{t}_{0}\ensuremath{\simeq}1$ consistent with limits from gravitational lens statistics.
15028896
Fractal theory space: Space-time of noninteger dimensionality
We construct matter field theories in ``theory space'' that are fractal, and invariant under geometrical renormalization group (RG) transformations. We treat in detail complex scalars, and discuss issues related to fermions, chirality, and Yang-Mills gauge fields. In the continuum limit these models describe physics in a noninteger spatial dimension which appears above a RG invariant ``compactification scale,'' M. The energy distribution of KK modes above M is controlled by an exponent in a scaling relation of the vacuum energy (Coleman-Weinberg potential), and corresponds to the dimensionality. For truncated-s-simplex lattices with coordination number s the spacetime dimensionality is 1+(3+2ln(s)/ln(s+2)). The computations in theory space involve subtleties, owing to the 1+3 kinetic terms, yet the resulting dimensionalites are equivalent to thermal spin systems. Physical implications are discussed.
119473346
Renormalization group fixed points and the Higgs boson spectrum
Abstract We study numerically the renormalization group equations for the Higgs potential of the two-doublet model assuming perturbative unification and sufficiently large initial quartic and Higgs-Yukawa couplings such that the full nonlinearities interplay. We obtain predictions for the physical Higgs boson spectrum in the two-doublet model up to systematic differences in fermion coupling schemes. Unambiguous predictions emerge only when there exists a heavy generation in which quarks couple to both doublets. In other cases we find that the potential can become quartically unstable at low energies for arbitrary initial stable values of the coupling constants.
969079
Anomaly mediated neutrino-photon interactions at finite baryon density.
We propose new physical processes based on the axial vector anomaly and described by the Wess-Zumino-Witten term that couples the photon, Z-boson, and the omega-meson. The interaction takes the form of a pseudo-Chern-Simons term, approximately E(munurhosigma)omega(mu)ZnuFrhosigma. This term induces neutrino-photon interactions at finite baryon density via the coupling of the Z-boson to neutrinos. These interactions may be detectable in various laboratory and astrophysical arenas. The new interactions may account for the excess observed at the Fermilab Booster Neutrino Experiment MiniBooNE. They also produce a competitive contribution to neutron star cooling at temperatures greater, similar10(9) K. These processes and related axion-photon interactions at finite baryon density appear to be relevant in many astrophysical regimes.
121692361
First results of electron cooling experiments at LEAR
The first results are presented of electron cooling experiments in the Low-Energy Antiproton Ring (LEAR) at CERN, performed with a proton beam of about 50 and 21 MeV. The number of stored protons ranged from 107 to 3 × 109. Cooling times of the order 1 s and proton drag rates of up to 0.7 MeV/s were obtained. The capture of cooling electrons by protons producing hydrogen atoms was used to derive an effective electron temperature (0.25 eV). From the angular profile of the neutral hydrogen beam an upper limit of 3π mm.mrad could be deduced for the horizontal equilibrium proton-beam emittance. The lowest equilibrium momentum spread was 2 × 105 (FWHM), as derived from the analysis of the longitudinal Schottky signal. This Schottky signal exhibited an unusual behaviour with beam intensity and under certain conditions showed a doublepeak structure which was associated with collective beam noise. For very cold beams transverse instabilities were observed, which resulted in a rapid spill-off of protons and a stabilization at lower intensities. The threshold of these instabilities was raised by heating the proton or the electron beam. The cooling of a bunched proton beam was investigated. The reduction of the proton momentum spread led to bunch lengths of about 2 m, containing 3 × 108 protons.
56569647
EXPERIMENTAL INVESTIGATION OF ELECTRON COOLING AND STACKING OF LEAD IONS IN A LOW ENERGY ACCUMULATION RING
This report gives the results of a programme of experimental investigations, which were carried out to test stacking of lead ions in a storage ring (the former Low Energy Anti­ proton Ring, LEAR) at 4.2 MeV per nucleon. The motivation was to demonstrate the feasibility of gaining the large factor in the phase-space density required for injection into the Large Hadron Collider (LHC). In the first part of the report, the layout of the experiments is described, the choice of the parameters of the electron cooling system used for stacking is reported and the multiturn injection using horizontal- and longitudinal­ (and in the final project also vertical-) phase space is discussed. In the second part the experimental results are presented. Factors ofvital importance are the stacking efficiency, the beam life-time and the cooling time of the ions. The beam decay owing to charge exchange with the residual gas and to recombination by the capture of cooling electrons was intensively studied. Beam instabilities and space-charge effects in the ion beamturned out to be additional, although less serious, limitations of the accumulation rate. The cooling speed as a function of cooler and storage-ring properties was investigated over a wide range of parameters. Among the 'surprises' encountered are an anomalously fast recombination rate for certain ion charge states (Pb 53 +), a strong dependence of the cooling time on the dispersion function of the storage ring, and an intensity-dependent outgassing ofequipment in the vacuum chamber. After a careful choice ofparameters and antidotes, an overall factor of 120 in intensity could be gained, by multi-turn injection and stacking for 4 s. The intensity obtained (6 x 10 8 ions with a length corresponding to four LHC bunches) is only a factor oftwo short of the LHC requirement, and the stacking time (4 s instead of 2 s foreseen for filling each LHC ring in 8 min) is another factor of 2 off.
123347831
CERN heavy-ion facility design report
122904939
Numerical Simulation and Interpretation of the Results of Lead Ion Production in the ECR Ion Source at CERN
A new library of the computer codes for the mathematical simulation of heavy ion production in the ECR ion source is presented. These codes are based on the equations of model of ion confinement and losses in ECR ion sources.
119888083
Stochastic cooling and storage tests with oxygen ions in LEAR
O/sup 8+/ and O/sup 6+/ ions were stored in the CERN Low-Energy Antiproton Ring (LEAR) during a machine experiment session. The aim was to obtain some hints on the lifetime of heavy ion beams in a good cooling ring vacuum and to test cooling and stacking of ions. Stochastic cooling was used to compensate the beam decay due to multiple scattering on the residual gas, which is the most important effect on lifetime. An equilibrium momentum spread of less than 5*10/sup -4/ was measured, thus proving the efficiency of stochastic cooling for multiply charged ions. With the vacuum conditions of LEAR (2.6*10/sup -12/ torr gauge reading with a residual gas of 90% H/sub 2/), measured beam lifetimes are 25 min for O/sup 6+/ at 7.2 MeV/u and 600 min for O/sup 8+/ at 11.5 MeV/u. These numbers set favorable limits for low-energy ion storage rings.<<ETX>>