448 research outputs found

    Consistent Batalin--Fradkin quantization of Infinitely Reducible First Class Constraints

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    We reconsider the problem of BRST quantization of a mechanics with infinitely reducible first class constraints. Following an earlier recipe [Phys. Lett. B 381, 105, (1996)], the original phase space is extended by purely auxiliary variables, the constraint set in the enlarged space being first stage of reducibility. The BRST charge involving only a finite number of ghost variables is explicitly constructed.Comment: 5 pages, LaTex. Minor corrections including the title. The version to appear in Phys. Rev.

    Gravitational Coupling and Dynamical Reduction of The Cosmological Constant

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    We introduce a dynamical model to reduce a large cosmological constant to a sufficiently small value. The basic ingredient in this model is a distinction which has been made between the two unit systems used in cosmology and particle physics. We have used a conformal invariant gravitational model to define a particular conformal frame in terms of large scale properties of the universe. It is then argued that the contributions of mass scales in particle physics to the vacuum energy density should be considered in a different conformal frame. In this manner, a decaying mechanism is presented in which the conformal factor appears as a dynamical field and plays a key role to relax a large effective cosmological constant. Moreover, we argue that this model also provides a possible explanation for the coincidence problem.Comment: To appear in GR

    Neutrino Masses in the Supersymmetric Standard Model with Right-Handed Neutrinos and Spontaneous R-Parity Violation

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    We propose an extension of the supersymmetric standard model with right-handed neutrinos and a singlet Higgs field, and study the neutrino masses in this model. The Majorana masses for the right-handed neutrinos are generated around the supersymmetry breaking scale through the vacuum expectation value of the singlet Higgs field. This model may induce spontaneous R-parity violation via the vacuum expectation value of the right-handed sneutrino. In the case, the effective theory is similar to a bilinear R-parity violating model. There are two sources for the neutrino masses: one is this bilinear R-parity breaking effect, and the other is the ordinary seesaw effect between left- and right-handed neutrinos. Combining these two effects, the hierarchical neutrino mass pattern arises even when the neutrino Yukawa matrices are not hierarchical. We acquire appropriate masses and mixings to explain both the solar and atmospheric neutrino oscillations.Comment: 22pages, RevTeX, 3 ps figures; a reference adde

    Dark Energy and Gravity

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    I review the problem of dark energy focusing on the cosmological constant as the candidate and discuss its implications for the nature of gravity. Part 1 briefly overviews the currently popular `concordance cosmology' and summarises the evidence for dark energy. It also provides the observational and theoretical arguments in favour of the cosmological constant as the candidate and emphasises why no other approach really solves the conceptual problems usually attributed to the cosmological constant. Part 2 describes some of the approaches to understand the nature of the cosmological constant and attempts to extract the key ingredients which must be present in any viable solution. I argue that (i)the cosmological constant problem cannot be satisfactorily solved until gravitational action is made invariant under the shift of the matter lagrangian by a constant and (ii) this cannot happen if the metric is the dynamical variable. Hence the cosmological constant problem essentially has to do with our (mis)understanding of the nature of gravity. Part 3 discusses an alternative perspective on gravity in which the action is explicitly invariant under the above transformation. Extremizing this action leads to an equation determining the background geometry which gives Einstein's theory at the lowest order with Lanczos-Lovelock type corrections. (Condensed abstract).Comment: Invited Review for a special Gen.Rel.Grav. issue on Dark Energy, edited by G.F.R.Ellis, R.Maartens and H.Nicolai; revtex; 22 pages; 2 figure

    Relating the CMSSM and SUGRA models with GUT scale and Super-GUT scale Supersymmetry Breaking

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    While the constrained minimal supersymmetric standard model (CMSSM) with universal gaugino masses, m_{1/2}, scalar masses, m_0, and A-terms, A_0, defined at some high energy scale (usually taken to be the GUT scale) is motivated by general features of supergravity models, it does not carry all of the constraints imposed by minimal supergravity (mSUGRA). In particular, the CMSSM does not impose a relation between the trilinear and bilinear soft supersymmetry breaking terms, B_0 = A_0 - m_0, nor does it impose the relation between the soft scalar masses and the gravitino mass, m_0 = m_{3/2}. As a consequence, tan(\beta) is computed given values of the other CMSSM input parameters. By considering a Giudice-Masiero (GM) extension to mSUGRA, one can introduce new parameters to the K\"ahler potential which are associated with the Higgs sector and recover many of the standard CMSSM predictions. However, depending on the value of A_0, one may have a gravitino or a neutralino dark matter candidate. We also consider the consequences of imposing the universality conditions above the GUT scale. This GM extension provides a natural UV completion for the CMSSM.Comment: 16 pages, 11 figures; added erratum correcting several equations and results in Sec.2, Sec.3 and 4 remain unaffected and conclusions unchange

    Cost-effectiveness of alirocumab in patients with acute coronary syndromes the ODYSSEY OUTCOMES trial

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    BACKGROUND Cholesterol reduction with proprotein convertase subtitisin-kexin type 9 inhibitors reduces ischemic events; however, the cost-effectiveness in statin-treated patients with recent acute coronary syndrome remains uncertain.OBJECTIVES This study sought to determine whether further cholesterol reduction with atirocumab would be cost-effective in patients with a recent acute coronary syndrome on optimal statin therapy.METHODS A cost-effectiveness model leveraging patient-level data from ODYSSEY OUTCOMES (Evaluation of Cardiovascular Outcomes After an Acute Coronary Syndrome During Treatment With Atirocumab) was developed to estimate costs and outcomes over a lifetime horizon. Patients (n = 18,924) had a recent acute coronary syndrome and were on high-intensity or maximum-tolerated statin therapy, with a baseline tow-density lipoprotein cholesterol (LDL-C) level >= 70 mg/l, non-high-density lipoprotein cholesterol >= 100 mg/dl, or apotipoprotein B >= 80 mg/l. Atirocumab 75 mg or placebo was administered subcutaneously every 2 weeks. Atirocumab was blindly titrated to 150 mg if LDL-C remained >= 50 mg/dl or switched to placebo if 2 consecutive LDL-C levels were = 100 mg/dl.RESULTS Across the overall population recruited to the ODYSSEY OUTCOMES trial, using an annual treatment cost of US5,850,themeanoverallincrementalcosteffectivenessratiowasUS5,850, the mean overall incremental cost-effectiveness ratio was US92,200 per QALY (base case). The cost was US41,800perQALYinpatientswithbaselineLDLC>=100mg/dl,whereasinthosewithLDLC>=100mg/dlthecostperQALYwasUS41,800 per QALY in patients with baseline LDL-C >= 100 mg/dl, whereas in those with LDL-C >= 100 mg/dl the cost per QALY was US299,400. Among patients with LDL-C a100 mg/dl, incremental cost-effectiveness ratios remained below US$100,000 per QALY across a wide variety of sensitivity analyses.CONCLUSIONS In patients with a recent acute coronary syndrome on optimal statin therapy, atirocumab improves cardiovascular outcomes at costs considered intermediate value, with good value in patients with baseline LDL-C mg/dt but less economic value with LDL-C >= 100 mg/dl. (Evaluation of Cardiovascular Outcomes After an Acute Coronary Syndrome During Treatment With Atirocumab [ODYSSEY OUTCOMES]; NCT01663402) (J Am Colt Cardiol 2020;75:2297-308) (C) 2020 The Authors. Published by Elsevier on behalf of the American College of Cardiology Foundation.Cardiolog

    Human Health Risk Assessment For Arsenic: A Critical Review

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    Millions of people are exposed to arsenic resulting in a range of health implications.This paper provides an up-to-date review of the different sources of arsenic (water, soil and food), indicators of human exposure (biomarker assessment of hair, nail, urine and blood), epidemiological and toxicological studies on carcinogenic and non-carcinogenic health outcomes, and risk assessment approaches. The review demonstrates a need for more work evaluating the risks of different arsenic species such as; arsenate, arsenite monomethylarsonic acid, monomethylarsonous acid, dimethylarsinic acid and dimethylarsinous acid as well as a need to better integrate the different exposure sources in risk assessments

    Properties of the Top Quark

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    The top quark was discoverd at the CDF and D0 experiments in 1995. As the partner of the bottom quark its properties within the Standard Model are fully defined. Only the mass is a free parameter. The measurement of the top quark mass and the verification of the expected properties have been an important topic of experimental top quark physics since. In this review the recent results on top quark properties obtained by the Tevatron experiments CDF and D0 are summarised. At the advent of the LHC special emphasis is given to the basic measurement methods and the dominating systematic uncertainties.Comment: Habilitation thesis, revised and updated for publication in EPJ

    The comparative responsiveness of Hospital Universitario Princesa Index and other composite indices for assessing rheumatoid arthritis activity

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    Objective To evaluate the responsiveness in terms of correlation of the Hospital Universitario La Princesa Index (HUPI) comparatively to the traditional composite indices used to assess disease activity in rheumatoid arthritis (RA), and to compare the performance of HUPI-based response criteria with that of the EULAR response criteria. Methods Secondary data analysis from the following studies: ACT-RAY (clinical trial), PROAR (early RA cohort) and EMECAR (pre-biologic era long term RA cohort). Responsiveness was evaluated by: 1) comparing change from baseline (Delta) of HUPI with Delta in other scores by calculating correlation coefficients; 2) calculating standardised effect sizes. The accuracy of response by HUPI and by EULAR criteria was analyzed using linear regressions in which the dependent variable was change in global assessment by physician (Delta GDA-Phy). Results Delta HUPI correlation with change in all other indices ranged from 0.387 to 0.791); HUPI's standardized effect size was larger than those from the other indices in each database used. In ACT-RAY, depending on visit, between 65 and 80% of patients were equally classified by HUPI and EULAR response criteria. However, HUPI criteria were slightly more stringent, with higher percentage of patients classified as non-responder, especially at early visits. HUPI response criteria showed a slightly higher accuracy than EULAR response criteria when using Delta GDA-Phy as gold standard. Conclusion HUPI shows good responsiveness in terms of correlation in each studied scenario (clinical trial, early RA cohort, and established RA cohort). Response criteria by HUPI seem more stringent than EULAR''s
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