Absolute elastic differential cross sections for electron scattering by C6H5CH3 and C6H5CF3 at 1.5–200 eV: a comparative experimental and theoretical study with C6H6

We present absolute differential cross sections DCS for elastic scattering from two benzene derivatives C6H5CH3 and C6H5CF3. The crossed-beam method was used in conjunction with the relative flow technique using helium as the reference gas to obtain absolute values. Measurements were carried out for scattering angles 15° –130° and impact energies 1.5–200 eV. DCS results for these two molecules were compared to those of C6H6 from our previous study. We found that 1 these three molecules have DCS with very similar magnitudes and shapes over the energy range 1.5–200 eV, although DCS for C6H5CF3 increase steeply toward lower scattering angles due to the dipole moment induced long-range interaction at 1.5 and 4.5 eV, and 2 that the molecular structure of the benzene ring significantly determines the collision dynamics. From the measured DCS, elastic integral cross sections have been calculated. Furthermore, by employing a corrected form of the independent-atom method known as the screen corrected additive rule, DCS calculations have been carried out without any empirical parameter fittings, i.e., in an ab initio nature. Results show that the calculated DCS are in excellent agreement with the experimental values at 50, 100, and 200 eV

Probing Intermediate Mass Higgs Interactions at the CERN Large Hadron Collider

We analyze the potentiality of the CERN Large Hadron Collider to probe the Higgs boson couplings to the electroweak gauge bosons. We parametrize the possible deviations of these couplings due to new physics in a model independent way, using the most general dimension--six effective lagrangian where the SU(2)_L x U(1)_Y is realized linearly. For intermediate Higgs masses, the decay channel into two photons is the most important one for Higgs searches at the LHC. We study the effects of these new interactions on the Higgs production mechanism and its subsequent decay into two photons. We show that the LHC will be sensitive to new physics scales beyond the present limits extracted from the LEP and Tevatron physics.Comment: 13 pages, 1 figure included using epsfig, RevTe

Neutrino Masses and Mixing one Decade from Now

We review the status of neutrino masses and mixings in the light of the solar and atmospheric neutrino data. The result from the LSND experiment is also considered. We discuss the present knowledge and the expected sensitivity to the neutrino mixing parameters in the simplest schemes proposed to reconcile these data some of which include a light sterile neutrino in addition to the three standard ones.Comment: 16 pages Latex file using elsart.sty. Seven postscript figures included. Talk given at the ICFA/ECFA Workshop "Neutrino Factories based on Muon Storage Rings, nu-FACT99", Lyon, July 1999. Typo in Eq. 8 correcte

Course of infection with Lymphocystis disease virus in gilthead seabream (Sparus aurata)

Lymphocystis disease virus (LCDV) is the etiological agent of lymphocystis disease (LCD), a pathology that affects a wide variety of fish species. Data about LCDV pathogenesis are very short, and mainly limited to histopathological studies of skin lesions. Recent studies on viral genome detection (both by PCR or DNA-DNA in situ hybridization) suggest that LCDV establish a systemic and persistent infection in gilthead seabream (Sparus aurata), but further studies are necessary to prove if this infection is productive or not. In the present study viral quantification and viral mRNA detection (by qPCR and RT-qPCR) have been used to investigate LCDV multiplication in different organs of juvenile gilthead seabream. In addition, a histopathological study was carried out. Animals were collected from two commercial farms in Southwestern Spain. In one farm, where no LCD outbreaks have been recorded, apparently healthy fish were collected, whereas in the other farm, diseased and recovered (two months after LCD symptoms disappearance) fish were sampled. All the animals were LCDV-infected, and viral gene expression was detected in every organ analysed (caudal fin, intestine, liver, spleen, kidney and brain). In asymptomatic animals, both apparently healthy and recovered, a low-titre infection was observed, with the highest viral copy numbers detected in brain and kidney. In diseased fish, viral loads were significantly higher than in subclinical infected animals, being maximal in caudal fin, where lymphocysts were present in the dermis. Different histological alterations were observed in the internal organs from diseased fish analysed, although no hypertrophied cells were detected in any of them. In recovered fish, most of the organs examined presented similar histological features to those in healthy animals. Thus, pathological changes were only detected in the intestine and liver, although they were less severe than those observed in diseased fish. The results presented showed that LCDV establishes a systemic infection in juvenile gilthead seabream, which can be subclinical. In addition, although the disease is self-limiting, the virus is not removed after disease recovery, but produces a persistent infection.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Update on Solar and Atmospheric Four-Neutrino Oscillations

In this talk we present the update (including the recent SNO results) of our analysis of the neutrino oscillation solutions of the solar and atmospheric neutrino problems in the framework of four-neutrino mixing where a sterile neutrino is added to the three standard ones and the mass spectra present two separated doublets. Such scenarios allow for simultaneous transitions of solar $\nu_e$, as well as atmospheric $\nu_\mu$, into a combination of active and sterile neutrinos. We evaluate the allowed active-sterile admixture in both solar and atmospheric oscillations from the combined analysis. Our results show that, although the Super-Kamiokande data disfavour both the pure $\nu_\mu\to\nu_s$ atmospheric channel and, in combination with SNO, the pure $\nu_e\to\nu_s$ solar channel, the result from the combined analysis still favours close-to-pure active and sterile oscillations and disfavours oscillations into a near-maximal active-sterile admixture.In this talk we present the update (including the recent SNO results) of our analysis of the neutrino oscillation solutions of the solar and atmospheric neutrino problems in the framework of four-neutrino mixing where a sterile neutrino is added to the three standard ones and the mass spectra present two separated doublets. Such scenarios allow for simultaneous transitions of solar $\nu_e$, as well as atmospheric $\nu_\mu$, into a combination of active and sterile neutrinos. We evaluate the allowed active-sterile admixture in both solar and atmospheric oscillations from the combined analysis. Our results show that, although the Super-Kamiokande data disfavour both the pure $\nu_\mu\to\nu_s$ atmospheric channel and, in combination with SNO, the pure $\nu_e\to\nu_s$ solar channel, the result from the combined analysis still favours close-to-pure active and sterile oscillations and disfavours oscillations into a near-maximal active-sterile admixture.In this talk we present the update (including the recent SNO results) of our analysis of the neutrino oscillation solutions of the solar and atmospheric neutrino problems in the framework of four-neutrino mixing where a sterile neutrino is added to the three standard ones and the mass spectra present two separated doublets. Such scenarios allow for simultaneous transitions of solar $\nu_e$, as well as atmospheric $\nu_\mu$, into a combination of active and sterile neutrinos. We evaluate the allowed active-sterile admixture in both solar and atmospheric oscillations from the combined analysis. Our results show that, although the Super-Kamiokande data disfavour both the pure $\nu_\mu\to\nu_s$ atmospheric channel and, in combination with SNO, the pure $\nu_e\to\nu_s$ solar channel, the result from the combined analysis still favours close-to-pure active and sterile oscillations and disfavours oscillations into a near-maximal active-sterile admixture.In this talk we present the update (including the recent SNO results) of our analysis of the neutrino oscillation solutions of the solar and atmospheric neutrino problems in the framework of four-neutrino mixing where a sterile neutrino is added to the three standard ones and the mass spectra present two separated doublets. Such scenarios allow for simultaneous transitions of solar $\nu_e$, as well as atmospheric $\nu_\mu$, into a combination of active and sterile neutrinos. We evaluate the allowed active-sterile admixture in both solar and atmospheric oscillations from the combined analysis. Our results show that, although the Super-Kamiokande data disfavour both the pure $\nu_\mu\to\nu_s$ atmospheric channel and, in combination with SNO, the pure $\nu_e\to\nu_s$ solar channel, the result from the combined analysis still favours close-to-pure active and sterile oscillations and disfavours oscillations into a near-maximal active-sterile admixture

CP Violation from Scatterings with Gauge Bosons in Leptogenesis

We present an explicit computation of the CP asymmetry in scattering processes involving the heavy right-handed neutrinos of the type I seesaw framework and the Standard Model gauge bosons. Compared to CP violation in two--body decays and in scatterings with top quarks there are new contributions at one loop in the form of new type of vertex corrections as well as of box diagrams. We show that their presence implies that, unlike the CP asymmetry in scatterings with top quarks, the CP asymmetry in scatterings with gauge bosons is different from the two-body decay asymmetry even for hierarchical right-handed neutrinos. This also holds for the L-conserving CP asymmetry in scatterings with U(1)$_Y$ gauge bosons.Comment: 13 pages, 3 figure

Global and Unified Analysis of Solar Neutrino Data

We discuss the status of the solutions of the solar neutrino problem in terms of oscillations of $\nu_e$ into active or sterile neutrinos. We present the results of a global fit to the full data set corresponding to the latest data presented at the $\nu$-2000 conference. We show the possible solutions in the full parameter space including both MSW and vacuum, as well as quasi-vacuum oscillations (QVO) and matter effects for mixing angles in the second octant (the so called dark side). Our conclusion is that from the statistical point of view, all solutions for oscillations into active neutrinos: LMA, LOW, SMA and the QVO solutions are acceptable since they all provide a reasonable GOF to the full data set. The same holds for the SMA solution for oscillations into sterile neutrinos. LMA and LOW-QVO solutions for oscillations into active neutrinos seem slightly favoured over SMA solutions for oscillations into active or sterile neutrinos. We also analyze the dependence of these conclusions on the uncertainty of the SSM $^8$B flux and on the removal of the data from one of the experimental rates. We also present the results in the framework of four neutrino oscillations which allows for oscillations into a state which is a combination of active and sterile neutrino.Comment: 18 pages with 18 postscript figures included (some of them bitmapped for compression, better resolution at http://ific.uv.es/~penya

Effect of the North Equatorial Counter Current on the generation and propagation of internal solitary waves off the Amazon shelf (SAR observations)

Synthetic aperture radar (SAR) imagery from the Amazon shelf break region in the tropical west Atlantic reveals for the first time the two-dimensional horizontal structure of an intense Internal Solitary Wave (ISW) field, whose first surface manifestations are detected several hundred kilometres away from the nearest forcing bathymetry. Composite maps and an energy budget analysis (provided from the Hybrid Coordinate Ocean Model - HYCOM) help to identify two major ISW pathways emanating from the steep slopes of a small promontory (or headland) near 44 degrees W and 0 degrees N, which are seen to extend for over 500 km into the open ocean. Further analysis in the SAR reveals propagation speeds above 3 ms(-1), which are amongst the fastest ever recorded. The main characteristics of the ISWs are further discussed based on a statistical analysis, and seasonal variability is found for one of the ISW sources. This seasonal variability is discussed in light of the North Equatorial Counter Current. The remote appearance of the ISW sea surface manifestations is explained by a late disintegration of the internal tide (IT), which is further investigated based on the SAR data and climatological monthly means (for stratification and currents). Acknowledging the possibility of a late disintegration of the IT may help explain the remote-sensing views of other ISWs in the world's oceans