119866130
Determination of the proton separation energy of Rh93 from mass measurements
The proposed {nu}p process, which occurs in the early time proton-rich neutrino winds of core-collapse supernovae, has the potential to resolve the long-standing uncertainty in the production of the light p-nuclei {sup 92}Mo and {sup 94}Mo. A recent study incorporating this {nu}p process has indicated that the proton separation energy S{sub p} of {sup 93}Rh is especially important in determining the relative production of these two isotopes. To reproduce the observed solar {sup 92}Mo/{sup 94}Mo abundance ratio of 1.57 a S{sub p} value for {sup 93}Rh of 1.64 {+-} 0.1 MeV is required. The previously unknown masses of {sup 92}Ru and {sup 93}Rh have been measured with the Canadian Penning Trap mass spectrometer resulting in an experimental value for S{sub p}({sup 93}Rh) of 2.007 {+-} 0.009 MeV. This implies that with our current understanding of the conditions in core-collapse supernova explosions the {nu}p process is not solely responsible for the observed solar {sup 92}Mo/{sup 94}Mo abundance ratio.
18308235
Search for new particles in hadronic events with isolated photons
Abstract A search for the neutral Higgs boson in the processes e + e − → Z → H 0 γ → q q γ and e + e − → Z → Z ∗ H 0 → q q γγ has been performed using 2.8 million hadronic Z decays collected with the L3 detector at LEP from 1991 through 1994. No evidence for these processes has been observed. Upper limits at 95% confidence level for the corresponding cross sections have been set and the results have been compared with theoretical predictions beyond the Standard Model.
121941527
B∗ production in Z decays at LEP
Abstract The production of B ∗ mesons in Z decays has been measured at LEP with the L3 detector. A sample of Z → b b events was obtained by tagging muons in 1.6 million hadronic Z decays collected in 1991, 1992 and 1993. A signal with a peak value of E γ = 46.3 ± 1.9 (stat) MeV in the B rest frame energy spectrum was interpreted to come from the decay B ∗ → γB. The inclusive production ratio of B ∗ mesons relative to B mesons was determined from a fit to the spectrum to be N B ∗ (N B ∗ + N B ) = 0.76 ± 0.08 ± 0.06 , where the first error is statistical and the second is systematic.
122717574
Search for neutralinos in Z decays
Abstract We have searched for neutralinos produced via the reactions e + e − → χχ′ and e + e − → χ′χ′, where the next-to lightest neutralino, χ′, decays into the lightest neutralino, χ, and either a photon or a fermion pair. Based on 1.8 × 10 6 hadronic Z decays collected with the L3 detector at LEP, no signal has been observed. We present upper limits of a few times 10 −5 on the branching ratios Z → χχ′ and Z → χ′χ′. In the framework of the Minimial Supersymmetric Standard Model, we exclude a lightest χ with m χ less than 18 GeV, if either tan β > 2 or the gluino mass m ≈ g > 100 GeV.
122052372
Angular multiplicity fluctuations in hadronic Z decays and comparison to QCD models and analytical calculations
Abstract Local multiplicity fluctuations in angular phase space intervals are studied using factorial moments measured in hadronic events at s ≃91.2 GeV , which were collected by the L3 detector at LEP. Parton shower Monte Carlo programs agree well with the data. On the other hand, first-order QCD calculations in the Double Leading Log Approximation and the Modified Leading Log Approximation are found to deviate significantly from the data.
11916638
Precise mass measurement of 68Se, a waiting-point nuclide along the rp process.
Mass measurements of 68Ge, 68As, and 68Se have been obtained with the Canadian Penning Trap mass spectrometer. The results determine the mass excess of 68Se as -54 232(19) keV, the first measurement with a precision and reliability sufficient to address the light-curve and energy output of x-ray bursts as well as the abundances of the elements synthesized. Under typical conditions used for modeling x-ray bursts, 68Se is found to cause a significant delay in the rp process nucleosynthesis.
106635092
Fabrication Studies for a Cylindrical DDS Structure at 90 GHz
A natural extension of work on the next generation of high power RF sources and accelerating cavities for Linear Colliders implies cylindrical, damped, detuned structures for millimeter wavelengths. Commercial availability of WR-10 waveguides and other components in the 75-110 GHz range provides a practical goal. Fabrication methods are surveyed, compared and, in some cases, tested to determine whether they can provide the imposed tolerances. Different techniques and tolerances are compared to previous methods at longer wavelengths. The higher gradients and corresponding surface fields indicate that a better understanding of the surface physics is required as well as how the different fabrication steps influence those surface characteristics that impact the final operation. We consider existing systems at SLAC and elsewhere as a function of frequency to determine what is desirable to measure and control for all phases of the fabrication, testing, conditioning and use of these systems. For example, the importance of crystal structure to the different steps is discussed. The preferred method allows a variety of design alternatives to be pursued simultaneously and extends to shorter wavelengths as well as provides possibilities for embedded test and control elements.
20110707
Measurement of the inclusive 3-jet production differential cross section in proton–proton collisions at 7 TeV and determination of the strong coupling constant in the TeV range
This paper presents a measurement of the inclusive 3-jet production differential cross section at a proton–proton centre-of-mass energy of 7 TeV using data corresponding to an integrated luminosity of 5$$\,\mathrm{fb}^{-1}$$fb-1collected with the CMS detector. The analysis is based on the three jets with the highest transverse momenta. The cross section is measured as a function of the invariant mass of the three jets in a range of 445–3270 GeV and in two bins of the maximum rapidity of the jets up to a value of 2. A comparison between the measurement and the prediction from perturbative QCD at next-to-leading order is performed. Within uncertainties, data and theory are in agreement. The sensitivity of the observable to the strong coupling constant $$\alpha _\mathrm {S}$$αS is studied. A fit to all data points with 3-jet masses larger than 664 GeV gives a value of the strong coupling constant of $$\alpha _S(M_\mathrm{Z}) = 0.1171 \pm 0.0013\,\text {(exp)} \,^{+0.0073}_{-0.0047}\,\text {(theo)} $$αS(MZ)=0.1171±0.0013(exp)-0.0047+0.0073(theo).
15479152
Measurements of the mass, total width, and two-photon partial width of the eta(c) meson.
Using 13.4 fb(-1) of data collected with the CLEO detector at the Cornell Electron Storage Ring, we have observed 300 events for the two-photon production of ground-state pseudoscalar charmonium in the decay eta(c)-->K(0)(S)K-/+pi(+/-). We have measured the eta(c) mass to be [2980.4+/-2.3 (stat)+/-0.6 (syst)] MeV and its full width as [27.0+/-5.8 (stat)+/-1.4 (syst)] MeV. We have determined the two-photon partial width of the eta(c) meson to be [7.6+/-0.8 (stat)+/-0.4 (syst)+/-2.3 (br)] keV, with the last uncertainty associated with the decay branching fraction.
119206726
DOES M31 RESULT FROM AN ANCIENT MAJOR MERGER
The M31 haunted halo is likely associated with a rich merger history, currently assumed to be caused by multiple minor mergers. Here we use the GADGET2 simulation code to test whether M31 could have experienced a major merger in its past history. Our results indicate that a (3 ± 0.5):1 gaseous-rich merger with r pericenter = 25 ± 5 kpc and a polar orbit can explain many properties of M31 and of its halo. The interaction and fusion may have begun 8.75 ± 0.35 and 5.5 ± 0.5 Gyr ago, respectively. Observed fractions of the bulge and the thin and thick disks can be retrieved for a star formation history that is almost quiescent before the fusion. This also accords well with the observed relative fractions of intermediate age and old stars in both the thick disk and the Giant Stream. In this model, the Giant Stream is caused by returning stars from a tidal tail which contains material previously stripped from the satellite prior to the fusion. These returning stars are trapped into elliptical orbits or loops for long periods of time which can reach a Hubble time, and belong to a plane that is 45° offset from the M31 disk position angle. Because these streams of stars are permanently fed by new infalling stars with high energy from the tidal tail, we predict large loops which scale rather well with the features recently discovered in the M31 outskirts. We demonstrate that a single merger could explain first-order (intensity and size), morphological, and kinematical properties of the disk, thick disk, bulge, and streams in the halo of M31, as well as the observed distribution of stellar ages, and perhaps metallicities. This challenges the current scenarios assuming that each feature in the disk (the 10 kpc ring) or in its outskirts (thick disk, the Giant Stream, and the numerous streams) is associated with an equivalent number of minor mergers. Given the large number of parameters, further constraints are certainly required to better render the complexity of M31 and of the substructures within its halo which may ultimately lead to a more precise geometry of the encounter. This would allow us, in principle, to evaluate the impact of such a major event on the Andromeda system and the Local Group.
120426567
The BTeV experiment
BTeV is an experiment being constructed at the Fermilab p p ¯ collider, designed to study mixing, CP violation, and rare decays of beauty and charm hadrons. The detector covers the forward region (10-300 mrad) and includes a state of the art silicon pixel detector providing real time information to the first level detached vertex trigger, a Ring Imaging Cherenkov detector, providing excellent charge particle identification, a PbWO 4 electromagnetic calorimeter, and a muon system.