166 research outputs found

    SUSY-GUTs, SUSY-Seesaw and the Neutralino Dark Matter

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    We will consider a SUSY-SU(5) with one right-handed neutrino with a large top like Yukawa coupling. Assuming universal soft masses at high scale we compute the low-energy spectrum and subsequently the neutralino LSP relic density taking also into consideration SU(5) as well as the see-saw running effects above the gauge coupling unification scale. We found that there exists no viable region in parameter space for \tan\beta \ler ~35. The τ~\tilde{\tau} coannihilation process starts becoming efficient for \tan\beta \ger 35-40. However, this process is significantly constrained by the limited range in which the stau is lighter than the neutralino. In fact, for a given tanβ\tan\beta we find that there exists an upper bound on the lightest neutralino mass (Mχ10M_{\chi_1^0}) in this region. The A-pole funnel region appears at very large tanβ4550\tan\beta \simeq 45-50, while the focus-point region does not make an appearance till large (m0,M1/2m_0,M_{1/2}), namely a few TeV. Large A0A_0 terms at high scale can lead to extended regions consistent with WMAP constraints and remove the upper bounds in the stau coannihilation regions.Comment: 18 pages, 7 figures; references added, figure added, improved discussions in text, to appear in JHE

    Smearing Formula for Higher-Order Effective Classical Potentials

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    In the variational approach to quantum statistics, a smearing formula describes efficiently the consequences of quantum fluctuations upon an interaction potential. The result is an effective classical potential from which the partition function can be obtained by a simple integral. In this work, the smearing formula is extended to higher orders in the variational perturbation theory. An application to the singular Coulomb potential exhibits the same fast convergence with increasing orders that has been observed in previous variational perturbation expansions of the anharmonic oscillator with quartic potential.Comment: Author Information under http://www.physik.fu-berlin.de/~kleinert/institution.html . Latest update of paper also at http://www.physik.fu-berlin.de/~kleinert/kleiner_re267/preprint.htm

    Inclusive Jet Production, Parton Distributions, and the Search for New Physics

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    Jet production at the Tevatron probes some of the smallest distance scales currently accessible. A gluon distribution that is enhanced at large x compared to previous determinations provides a better description of the Run 1b jet data from both CDF and D0. However, considerable uncertainty still remains regarding the gluon distribution at high x. In this paper, we examine the effects of this uncertainty, and of the remaining uncertainties in the NLO QCD theory, on jet cross section comparisons to Run 1b data. We also calculate the range of contributions still possible from any new physics. Predictions are also made for the expanded kinematic range expected for the ongoing Run 2 at the Tevatron and for the LHC.Comment: 50 pages, 31 figures, RevTe

    The Higgs intense--coupling regime in constrained SUSY models and its astrophysical implications

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    We analyze the Higgs intense--coupling regime, in which all Higgs particles of the Minimal Supersymmetric Standard Model are light with masses of the same order and the value of \tb the ratio of vacuum expectation values of the two Higgs fields is large, in the framework of Supergravity scenarios with non--universal soft Supersymmetry breaking scalar masses in the Higgs sector. In particular, we calculate the relic density abundance of the lightest neutralino candidate for cold dark matter and the rates in direct and indirect detection at present and future experiments. We first show that while in the mSUGRA model this regime is disfavored by present data, there are regions in the parameter space of models with non--universal Higgs masses where it can occur. We then show that because of the large value of tanβ\tan\beta and the relatively low values of the neutral Higgs boson masses, the cross section for neutralino--nucleon scattering is strongly enhanced in this regime and would allow for the observation of a signal in direct detection experiments such as CDMS--Soudan. The expected sensitivity of gamma--ray detectors like GLAST might be also sufficient to observe the annihilation of neutralinos in such a regime.Comment: 19 pages, 5 figure

    The relationship between alcohol consumption and related harm among young university students

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    Issue addressed: Research has shown that Australian university students consume alcohol at a higher level than their peers from the general population and are therefore more likely to witness and experience alcohol-related harm. This study measured the prevalence of alcohol consumption among 18–24-year-old university students and the association between alcohol consumption and witnessed and experienced harms. Methods: A random cross-sectional sample of university students aged 18–24 years (n = 2466) was recruited via the University Survey Office and through random intercept at campus market day. All participants completed an online survey that included the Alcohol Use Disorders Identification Test, Alcohol Problems Scale and an additional scale measuring witnessed harm. Results: Principal Components Analysis revealed three factors within the Alcohol Problems Scale; i.e. Criminal and Aggressive Behaviour, Health and Emotional Harms and Sexual Harms. Students who consume alcohol at high-risk levels were significantly more likely to score highly on each factor, 1.6 times more likely to experience harm and 1.1 times more likely to witness harm than students who consume alcohol at low-risk levels. Conclusions: The positive association between alcohol consumption and alcohol-related harm supports previous findings. This study adds previous research through the categorisation of harm into factors

    Evidence for Planet-induced Chromospheric Activity on HD 179949

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    We have detected the synchronous enhancement of Ca II H & K emission with the short-period planetary orbit in HD 179949. High-resolution spectra taken on three observing runs extending more than a year show the enhancement coincides with phi ~ 0 (the sub-planetary point) of the 3.093-day orbit with the effect persisting for more than 100 orbits. The synchronous enhancement is consistent with planet-induced chromospheric heating by magnetic rather than tidal interaction. Something which can only be confirmed by further observations. Independent observations are needed to determine whether the stellar rotation is sychronous with the planet's orbit. Of the five 51 Peg-type systems monitored, HD 179949 shows the greatest chromospheric H & K activity. Three others show significant nightly variations but the lack of any phase coherence prevents us saying whether the activity is induced by the planet. Our two standards, tau Ceti and the Sun, show no such nightly variations.Comment: 10 pages, 6 figures. Submitted to Ap

    Detailed engineering design of Puskesmas`watsan facilities

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