119870151
A naturally heavy fourth generation neutrino
Abstract We propose that there exists a fourth generation, all neutrinos have Dirac masses of order the corresponding charge lepton partner, and right-handed neutrinos have Majorana masses of order the weak scale. The see-saw mechanism then implies the light neutrino masses are O( mM lepton 2 / M ), while a fourth generation neutrino is heavy with mass O( M )∼O( M w ), and would not have been seen in the Z 0 width a LEP. Such a solution appears to be compatile with all known phenomenological and cosmological constraints, and predicts masses for neutrinos near their current upper bounds.
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.
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.
55284518
High current, high frequency ECRIS development program for LHC havy ion beam application
A research program with the aim of producing pulsed currents with hitherto unequalled intensity of Pb 27+ , with length and repetition rate compatible with those desired by CERN (1 mAe / 400 μs / 10 Hz in the context of future heavy ion collisions at LHC) is organised in a collaboration between CERN/GSI/CEA-Grenoble and IN2P3-ISNGrenoble. Two main experimental programs will be carried out : (i) tests with the LNS-Catania team on the SERSE superconducting source with a 28 GHz gyrotron, (ii) tests on a nonsuperconducting source (new source at Grenoble) with a 28 GHz gyrotron. For this purpose CEA/DRFMC has borrowed from CEA a 28 GHz 10 kW gyrotron transmitter. The project includes also the construction of a source body, by ISNG, with conventional coils and permanent magnets for working at the frequency of about 28 GHz and biased up to 60 kV. This source called PHOENIX will run on a test bench at ISN. PHOENIX is an improvement of the present ECR4-14.5 GHz/CERN source, having a mirror ratio R=2 at 14.5 GHz, and R=1.7 at 28 GHz (possibly reaching 2.1 T on the axis of the source), and with a plasma volume up to 2.5 larger. Experiments at 28 GHz will be performed on the SERSE source in Catania at INFN/LNS where both the axial and the hexapolar fields will be varied so that the mirror ratio is continuously varied up to R=1.6 ; the SERSE source will be also operated at lower magnetic fields such as those which can be produced by conventional magnets (less than 2 T axial field at injection far from the 28 GHz High-B mode).
123523434
Effect of a biased probe on the afterglow operation of an ECR4 ion source
Various experiments have been performed on a 14.5 GHz ECR4 in order to improve the ion yield. The source runs in pulsed afterglow mode, and provides currents ∼120 eμA of Pb27+ to the CERN Heavy Ion Facility on an operational basis. In the search for higher beam intensities, the effects of a pulsed biased disk on axis at the injection side were investigated with different pulse timing and voltage settings. No proof for absolute higher intensities was seen for any of these modifications. However, the yield from a poorly tuned/low-performing source could be improved and the extracted pulse was less noisy with bias voltage applied. The fast response on the bias implies that increases/decreases are not due to ionization processes. A good tune for high yield of high charge states during the afterglow coincides with a high plasma potential.
109966470
DESIGN, CONSTRUCTION AND OPERATION OF THE NEW CERN SC RF SYSTEM
A fast cycling RF-system giving high energy-gain per revolution was required to overcome the intensity limitations set by space-charge in the CERN SC. All other frequency modulation methods being discarded for power reasons, a high Q system tuned by a rotary capacitor was chosen.
92814731
Performance of the ECR ion source of CERN's heavy ion injector
In fall 1994 the new heavy ion injector at CERN was brought into operation successfully and a lead beam of 2.9 ×10 ions per pulse was accelerated in the SPS up to an energy of 157 GeV/u. The ion source, whi h was supplied by GANIL (France) was in operation almost continuously over a period of about one year and proved to be very reliable. It produces a current of more than 100 μA of Pb 27+ (after the first spectrometer) during the afterglow of the pulsed discharge. The current stays within 5% of the maximum value for a time of about 1 ms, which is more than required by the accelerators. Measurements of the charge state distribution, emittance and energy spread, which were made during this time window, are presented together with other operating data. Presented at the 12th International Workshop on ECR Ion Sources, April 25-27, 1995, RIKEN, Japan
137745598
Concept for a lead-ion accelerating facility at CERN