311 research outputs found

    SU(2) Glueballs, diquarks and mesons in dense matter

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    We present preliminary results from a high statistics study of 2-color QCD at low temperature and non-zero baryon density. The simulations are carried out on a 6^3*12 lattice and use a standard hybrid molecular dynamics algorithm for staggered fermions for two values of quark mass. Observables include glueball correlators evaluated via a multi-step smearing procedure as well as scalar and vector mesons and diquarks.Comment: Poster presented at Lattice 2003 (Non zero temperature and density), 3 pages, 4 figure

    Glueballs and mesons in the superfluid phase of two-color QCD

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    QCD with two colors undergoes a transition to a superfluid phase with diquark condensate when the quark chemical potential equals half the pion mass. We investigate the gluonic aspects of the transition by inspecting the behavior of the glueball correlators evaluated via a multi-step smearing procedure for several values of chemical potential ranging between zero and the saturation threshold. The results are based on an analysis of 0++ glueball correlators, on a sample of 40000 independent configurations on each parameter set. The amplitudes of the correlators peak for \mu = m_\pi/2,indicating that the superfluid phase transition affects the gluonic sector as well. The mass of the fundamental state decreases in the superfluid phase, and the amplitude of the propagators drops, suggesting a reduction of the gluon condensate, in agreement with model calculations. The analysis of the smearing dependence of the results helps disentangling the role of long and short distance phenomena at the superfluid transition.Comment: 7 pages, 5 figures, talk presented at the XXV International Symposium on Lattice Field Theory, July 30 - August 4, 2007, Regensburg,German

    Supplemental LED increases tomato yield in mediterranean semi-closed greenhouse

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    Supplemental light (SL) is a technique used to increase horticulture yield, especially in northern countries, where the Daily Light Integral (DLI) is a limiting factor during fall and winter, and which could also be used to obtain higher tomato yield at the mediterranean latitude. In this study, three tomato hybrid (F1) cultivars were grown for year-round production in a commercial semi-closed glasshouse in Southern Italy: two of the cherry fruit-type (‘Juanita’ and ‘Sorentyno’) and one mini plum fruit-type (‘Solarino’). From 120 to 243 days after transplant, light-emitting diode (LED) toplights were used as SL, with a photoperiod of 18 h. The main climatic parameters inside and outside the glasshouse were recorded, and tomato plants’ development and yield were examined. Plants grown with LEDs had longer stems as compared to control treatment (9.53 vs. 8.79 m), a higher stem thickness and yielded more trusses. On average, the yield was 21.7% higher with LEDs. ‘Sorentyno’ was the cultivar with the highest cumulated productivity when it was grown under SL. However, the cultivar with best light use efficiency under LEDs was ‘Solarino’. Therefore, supplemental LED from mid-December until march enhanced tomato growth and yield, opening a favorable scenario for large-scale application of this technology also in the mediterranean area

    Lattice Gauge Fixing for Parameter Dependent Covariant Gauges

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    We propose a non-perturbative procedure to fix generic covariant gauges on the lattice. Varying the gauge parameter, this gauge fixing provides a concrete method to check numerically the gauge dependence of correlators measured on the lattice. The new algorithm turns out to converge with a good efficiency. As a preliminary physical result, we find a sensitive dependence of the gluon propagator on the gauge parameter.Comment: 10 pages (LaTeX2e), 5 eps figure

    Lattice Renormalization of Quark Operators

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    We have technically improved the non-perturbative renormalization method, proposed by Martinelli et al., by using quark momentum sources and sinks. Composite two-fermion operators up to three derivatives have been measured for Wilson fermions and Sheikholeslami-Wohlert improved fermions in the quenched approximation. The calculations are performed in the Landau gauge on 16^3x32 lattices at beta = 6.0 for 3 kappa values in each case. The improved sources greatly decrease the statistical noise. We extract and discuss here renormalization factors for local operators and moments of the structure functions for Wilson fermions.Comment: 3 pages, Latex, 6 figures. epsf.sty and espcrc2.sty needed. Talk given at Lattice9

    Histological and immunohistochemical characterisation of uterine adenocarcinoma in an Asian elephant (Elephas Maximus)

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    A 56-year-old nulliparous female Asian elephant (Elephas maximus) living at the zoological garden of Naples (Italy), with a clinical history of recurrent colic, was found in agonal state and humane euthanasia was elected. At necropsy the uterine body was moderately increased in size and the lumen was reduced due to a poorly demarcated and infiltrative neoplasm. Furthermore, multiple, whitish, firm nodules were present in both lungs. Histological examination of the uterinemass revealed epithelial cells arranged in tubular or solid pattern infiltrating the endometrium and the muscular layer. Immunohistochemical examination showed immunoreactivity of neoplastic cells to oestrogen receptors antibody. Pulmonary lesions were histologically and immunohistochemically superimposable to the epithelial uterine neoplasm. A definitive diagnosis of uterine adenocarcinoma with pulmonary metastases was made

    Non-perturbative quark mass renormalization

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    We show that the renormalization factor relating the renormalization group invariant quark masses to the bare quark masses computed in lattice QCD can be determined non-perturbatively. The calculation is based on an extension of a finite-size technique previously employed to compute the running coupling in quenched QCD. As a by-product we obtain the Λ\Lambda--parameter in this theory with completely controlled errors.Comment: Talk given at LATTICE '97, 6 pages, Latex source, 7 eps figures, needs epsfi

    Mature teratoma arising from an undescended testis in a horse: comparison between ultrasonographic and morphological features

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    Scant information is available on the ultrasonographic appearance of different testicular tumours in the stallion. Preoperative ultrasound imaging and gross and microscopic features of a testicular teratoma in a horse is described. An asymptomatic 4 years old cryptorchid Arabian horse was admitted for orchiectomy. Combined transabdominal and inguinal ultrasound examination revealed a large complex ovoid mass, containing both solid and cystic elements with internal echoes, located dorsally to the superficial inguinal ring. Two main hypoechoic cavities divided by a linear hyperechoic septum were evident, with a hyperechoic circular structure inside the lumen of the largest one. A tumour of the undescended testis was suspected. Ultrasound findings guided a provisional diagnosis of teratoma that was confirmed by histology following surgical removal of the tumour. Due to the correspondence between ultrasonographic and morphological features, trans-abdominal ultrasonography was conclusive in the preoperative planning

    Non-perturbative Renormalisation of Domain Wall Fermions: Quark Bilinears

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    We find the renormalisation coefficients of the quark field and the flavour non-singlet fermion bilinear operators for the domain wall fermion action, in the regularisation independent (RI) renormalisation scheme. Our results are from a quenched simulation, on a 16^3x32 lattice, with beta=6.0 and an extent in the fifth dimension of 16. We also discuss the expected effects of the residual chiral symmetry breaking inherent in a domain wall fermion simulation with a finite fifth dimension, and study the evidence for both explicit and spontaneous chiral symmetry breaking effects in our numerical results. We find that the relations between different renormalisation factors predicted by chiral symmetry are, to a good approximation, satisfied by our results and that systematic effects due to the (low energy) spontaneous chiral symmetry breaking and zero-modes can be controlled. Our results are compared against the perturbative predictions for both their absolute value and renormalisation scale dependence.Comment: 53 pages, 21 figures, revte
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