170 research outputs found

    Exploring the Spectrum of Heavy Quarkonium Hybrids with QCD Sum Rules

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    QCD Laplace sum rules are used to calculate heavy quarkonium (charmonium and bottomonium) hybrid masses in several distinct JPCJ^{PC} channels. Previous studies of heavy quarkonium hybrids did not include the effects of dimension-six condensates, leading to unstable sum rules and unreliable mass predictions in some channels. We have updated these sum rules to include dimension-six condensates, providing new mass predictions for the spectra of heavy quarkonium hybrids. We confirm the finding of other approaches that the negative-parity JPC=(0,1,2)−+, 1−−J^{PC}=(0,1,2)^{-+},\,1^{--} states form the lightest hybrid supermultiplet and the positive-parity JPC=(0,1)+−, (0,1,2)++J^{PC}=(0,1)^{+-},\,(0,1,2)^{++} states are members of a heavier supermultiplet. Our results disfavor a pure charmonium hybrid interpretation of the X(3872)X(3872), in agreement with previous work.Comment: Presented by RTK at the Theory Canada 9 Conference, held at Wilfrid Laurier University in June 2014. Submitted for the conference proceedings to be published in the Canadian Journal of Physics. 5 pages, 1 figure. Version 2: reference added, typo correcte

    QCD Sum Rule Analysis of Heavy Quarkonium Hybrids

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    We have studied the charmonium and bottomonium hybrid states with various JPCJ^{PC} quantum numbers in QCD sum rules. At leading order in αs\alpha_s, the two-point correlation functions have been calculated up to dimension six including the tri-gluon condensate and four-quark condensate. After performing the QCD sum rule analysis, we have confirmed that the dimension six condensates can stabilize the hybrid sum rules and allow the reliable mass predictions. We have updated the mass spectra of the charmonium and bottomonium hybrid states and identified that the negative-parity states with JPC=(0,1,2)−+,1−−J^{PC}=(0, 1, 2)^{-+}, 1^{--} form the lightest hybrid supermultiplet while the positive-parity states with JPC=(0,1)+−,(0,1,2)++J^{PC}=(0, 1)^{+-}, (0, 1, 2)^{++} belong to a heavier hybrid supermultiplet.Comment: 7 pages, 1 figures. Some minor edits have been made. Presentation at the DPF 2013 Meeting of the American Physical Society Division of Particles and Fields, Santa Cruz, California, August 13-17, 201

    Adiabatic orientation of rotating dipole molecules in an external field

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    The induced polarization of a beam of polar clusters or molecules passing through an electric or magnetic field region differs from the textbook Langevin-Debye susceptibility. This distinction, which is important for the interpretation of deflection and focusing experiments, arises because instead of acquiring thermal equilibrium in the field region, the beam ensemble typically enters the field adiabatically, i.e., with a previously fixed distribution of rotational states. We discuss the orientation of rigid symmetric-top systems with a body-fixed electric or magnetic dipole moment. The analytical expression for their "adiabatic-entry" orientation is elucidated and compared with exact numerical results for a range of parameters. The differences between the polarization of thermodynamic and "adiabatic-entry" ensembles, of prolate and oblate tops, and of symmetric-top and linear rotators are illustrated and identified.Comment: 18 pages, 4 figure

    Mass Spectrum of Heavy Quarkonium Hybrids

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    We have extended the calculation of the correlation functions of heavy quarkonium hybrid operators with various JPCJ^{PC} quantum numbers to include QCD condensates up to dimension six. In contrast to previous analyses which were unable to optimize the QCD sum-rules for certain JPCJ^{PC}, recent work has shown that inclusion of dimension six condensates stabilizes the hybrid sum-rules and permits reliable mass predictions. In this work we have investigated the effects of the dimension six condensates on the remaining channels. After performing the QCD sum-rule analysis, we update the mass spectra of charmonium and bottomonium hybrids with exotic and non-exotic quantum numbers. We identify that the negative-parity states with JPC=(0,1,2)−+,1−−J^{PC}=(0, 1, 2)^{-+}, 1^{--} form the lightest hybrid supermultiplet while the positive-parity states with JPC=(0,1)+−,(0,1,2)++J^{PC}=(0, 1)^{+-}, (0, 1, 2)^{++} belong to a heavier hybrid supermultiplet, confirming the supermultiplet structure found in other approaches. The hybrid with JPC=0−−J^{PC}=0^{--} has a much higher mass which may suggest a different excitation of the gluonic field compared to other channels. In agreement with previous results, we find that the JPC=1++J^{PC}=1^{++} charmonium hybrid is substantially heavier than the X(3872), which seems to preclude a pure charmonium hybrid interpretation for this state.Comment: 17 pages, 7 figures, 4 table

    The Systemic Redox Status Is Maintained in Non-Smoking Type 2 Diabetic Subjects Without Cardiovascular Disease:Association with Elevated Triglycerides and Large VLDL

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    Decreased circulating levels of free thiols (R-SH, sulfhydryl groups) reflect enhanced oxidative stress, which plays an important role in the pathogenesis of cardiometabolic diseases. Since hyperglycemia causes oxidative stress, we questioned whether plasma free thiols are altered in patients with type 2 diabetes mellitus (T2DM) without cardiovascular disease or renal function impairment. We also determined their relationship with elevated triglycerides and very low density lipoproteins (VLDL), a central feature of diabetic dyslipidemia. Fasting plasma free thiols (colorimetric method), lipoproteins, VLDL (nuclear magnetic resonance spectrometry), free fatty acids (FFA), phospholipid transfer protein (PLTP) activity and adiponectin were measured in 79 adult non-smoking T2DM subjects (HbA1c 51 ± 8 mmol/mol, no use of insulin or lipid lowering drugs), and in 89 non-smoking subjects without T2DM. Plasma free thiols were univariately correlated with glucose (r = 0.196, p < 0.05), but were not decreased in T2DM subjects versus non-diabetic subjects (p = 0.31). Free thiols were higher in subjects with (663 ± 84 µmol/L) versus subjects without elevated triglycerides (619 ± 91 µmol/L; p = 0.002). Age- and sex-adjusted multivariable linear regression analysis demonstrated that plasma triglycerides were positively and independently associated with free thiols (β = 0.215, p = 0.004), FFA (β = 0.168, p = 0.029) and PLTP activity (β = 0.228, p = 0.002), inversely with adiponectin (β = -0.308, p < 0.001) but not with glucose (β = 0.052, p = 0.51). Notably, the positive association of free thiols with (elevated) triglycerides appeared to be particularly evident in men. Additionally, large VLDL were independently associated with free thiols (β = 0.188, p = 0.029). In conclusion, circulating free thiols are not decreased in this cohort of non-smoking and generally well-controlled T2DM subjects. Paradoxically, higher triglycerides and more large VLDL particles are likely associated with higher plasma levels of thiols, reflecting lower systemic oxidative stress

    Local and Systemic Oxidative Stress Biomarkers for Male Infertility: The ORION Study

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    Infertility problems occur in around 10% of all couples worldwide, with male-factor infertility as the sole contributor in 20–30% of these cases. Oxidative stress (OS) is suggested to be associated with the pathophysiology of male infertility. In spermatozoa, OS can lead to damage to the cell membrane, resulting in disruption of DNA integrity and a decrease in motility. Established biomarkers for OS include free thiols and malondialdehyde (MDA), both representing different components of the reactive species interactome (RSI). This exploratory study aimed to investigate seminal plasma-free thiol and MDA levels in relation to semen parameters as defined by the World Health Organization (WHO) to determine if these markers are adequate to define local OS status. Furthermore, this study investigated if there is a relation between systemic and local OS status by comparing seminal concentrations of free thiol (R-SH, sulfhydryl groups, representing the extracellular redox status) and MDA (lipid peroxidation product) levels to those measured in serum. Free thiol and MDA measurements in both serum and semen plasma were performed in 50 males (18–55 y) of couples seeking fertility treatment. A significant positive correlation was found between seminal plasma-free thiol levels and sperm concentration and progressive motility (r = 0.383, p = 0.008 and r = 0.333, p = 0.022, respectively). In addition, a significant positive correlation was found between MDA levels in seminal plasma and sperm concentration (r = 0.314, p = 0.031). This study supports that seminal plasma-free thiols may be promising as local OS biomarkers. No associations were observed between local and systemic OS biomarker concentrations
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