847 research outputs found

    FastJet user manual

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    FastJet is a C++ package that provides a broad range of jet finding and analysis tools. It includes efficient native implementations of all widely used 2-to-1 sequential recombination jet algorithms for pp and e+e- collisions, as well as access to 3rd party jet algorithms through a plugin mechanism, including all currently used cone algorithms. FastJet also provides means to facilitate the manipulation of jet substructure, including some common boosted heavy-object taggers, as well as tools for estimation of pileup and underlying-event noise levels, determination of jet areas and subtraction or suppression of noise in jets.Comment: 69 pages. FastJet 3 is available from http://fastjet.fr

    Space-time inhomogeneity, anisotropy and gravitational collapse

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    We investigate the evolution of non-adiabatic collapse of a shear-free spherically symmetric stellar configuration with anisotropic stresses accompanied with radial heat flux. The collapse begins from a curvature singularity with infinite mass and size on an inhomogeneous space-time background. The collapse is found to proceed without formation of an even horizon to singularity when the collapsing configuration radiates all its mass energy. The impact of inhomogeneity on various parameters of the collapsing stellar configuration is examined in some specific space-time backgrounds.Comment: To appear in Gen. Relativ. Gra

    Thermodynamic and Tunneling Density of States of the Integer Quantum Hall Critical State

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    We examine the long wave length limit of the self-consistent Hartree-Fock approximation irreducible static density-density response function by evaluating the charge induced by an external charge. Our results are consistent with the compressibility sum rule and inconsistent with earlier work that did not account for consistency between the exchange-local-field and the disorder potential. We conclude that the thermodynamic density of states is finite, in spite of the vanishing tunneling density of states at the critical energy of the integer quantum Hall transition.Comment: 5 pages, 4 figures, minor revisions, published versio

    New Supersymmetric String Compactifications

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    We describe a new class of supersymmetric string compactifications to 4d Minkowski space. These solutions involve type II strings propagating on (orientifolds of) non Calabi-Yau spaces in the presence of background NS and RR fluxes. The simplest examples have descriptions as cosets, generalizing the three-dimensional nilmanifold. They can also be thought of as twisted tori. We derive a formula for the (super)potential governing the light fields, which is generated by the fluxes and certain ``twists'' in the geometry. Detailed consideration of an example also gives strong evidence that in some cases, these exotic geometries are related by smooth transitions to standard Calabi-Yau or G2 compactifications of M-theory.Comment: 43 pages, harvmac bi

    Improved tests of extra-dimensional physics and thermal quantum field theory from new Casimir force measurements

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    We report new constraints on extra-dimensional models and other physics beyond the Standard Model based on measurements of the Casimir force between two dissimilar metals for separations in the range 0.2--1.2 μ\mum. The Casimir force between an Au-coated sphere and a Cu-coated plate of a microelectromechanical torsional oscillator was measured statically with an absolute error of 0.3 pN. In addition, the Casimir pressure between two parallel plates was determined dynamically with an absolute error of 0.6\approx 0.6 mPa. Within the limits of experimental and theoretical errors, the results are in agreement with a theory that takes into account the finite conductivity and roughness of the two metals. The level of agreement between experiment and theory was then used to set limits on the predictions of extra-dimensional physics and thermal quantum field theory. It is shown that two theoretical approaches to the thermal Casimir force which predict effects linear in temperture are ruled out by these experiments. Finally, constraints on Yukawa corrections to Newton's law of gravity are strengthened by more than an order of magnitude in the range 56 nm to 330 nm.Comment: Revtex 4, 35 pages, 14 figures in .gif format, accepted for publication in Phys. Rev.

    Gravitational collapse without a remnant

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    We investigate the gravitational collapse of a spherically symmetric, inhomogeneous star, which is described by a perfect fluid with heat flow and satisfies the equation of state p=ρ/3p=\rho/3 or p=C\rho^\ga at its center. Different from the ordinary process of gravitational collapsing, the energy of the whole star is emitted into space. And the remaining spacetime is a Minkowski one at the end of the process.Comment: 9 pages, 9 figures, to appear in Int. J. Theor. Phy

    Where’s the “Everyday Black Woman”? An intersectional qualitative analysis of Black Women’s decision-making regarding HIV pre-exposure prophylaxis (PrEP) in Mississippi

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    Background: Black cisgender women in the U.S. South bear a disproportionate burden of HIV compared to cisgender women in other racial and ethnic groups and in any other part of the US. Critical to decreasing new HIV infections is the improved delivery of pre-exposure prophylaxis (PrEP) for Black cisgender women as it remains underutilized in 2021. Informed by intersectionality, the study sought to characterize the sociostructural influences on Black cisgender women’s deliberations about PrEP within the context of interlocking systems of oppression including racism, sexism, and classism. Methods: Six focus groups were conducted with 37 Black women residing in Jackson, Mississippi. This sample was purposively recruited to include Black cisgender women who were eligible for PrEP but had never received a PrEP prescription. Results: Six themes were identified as concerns during PrEP deliberation among Black women: 1) limited PrEP awareness, 2) low perceived HIV risk, 3) concerns about side effects, 4) concerns about costs, 5) limited marketing, and 6) distrust in the healthcare system. Three themes were identified as facilitators during PrEP deliberations: 1) women’s empowerment and advocacy, 2) need for increased PrEP-specific education, and 3) the positive influence of PrEP-engaged women’s testimonials. Black women shared a limited awareness of PrEP exacerbated by the lack of Black women-specific marketing. Opportunities to support Black women-specific social marketing could increase awareness and knowledge regarding PrEP’s benefits and costs. Black women also shared their concerns about discrimination in healthcare and distrust, but they felt that these barriers may be addressed by patient testimonials from PrEP-engaged Black women, empowerment strategies, and directly addressing provider biases. Conclusions: An effective response to PrEP implementation among Black women in the South requires developing programs to center the needs of Black women and carry out active strategies that prioritize peer advocacy while reinforcing positive and mitigating negative influences from broader social and historical contexts

    “PrEP’s just to secure you like insurance”: a qualitative study on HIV pre-exposure prophylaxis (PrEP) adherence and retention among black cisgender women in Mississippi

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    Background: Pre-exposure prophylaxis (PrEP) has the potential to reduce transmission of HIV among Black cisgender women in the Southern United States (U.S.); however, national data suggests that PrEP initiation is lowest in the South and among Black women compared to other U.S. regions and white women. This study applied intersectionality and PrEP multilevel resilience frameworks to assess how socio-structural and clinical contexts shaped PrEP persistence among Black cisgender women in Mississippi. Methods: Semi-structured interviews were conducted with eight Black cisgender women in Jackson, Mississippi. This sample was purposively recruited to include PrEP-initiated Black cisgender women. Results: Six themes identified that shaped PrEP care among Black cisgender women: (1) internal assets, (2) sole responsibility to HIV prevention, (3) added protection in HIV serodifferent relationships, (4) financial issues, (5) trust and distrust in the medical system, and (6) side effects. Black cisgender women reported that PrEP persistence increased control over their sexual health, reduced anxiety about HIV, and promoted self-care. Black cisgender women also indicated that medication assistance programs increased PrEP affordability resulting in continued persistence. Conclusions: In addition to preventing HIV, PrEP may yield secondary positive impacts on the health and relationships of Black cisgender women. However, very few Black cisgender women in the South are using PrEP given intersectional barriers and thus necessitates adaptive strategies to support PrEP initiation and persistence. Efforts aimed at increasing the coverage of PrEP among Black cisgender women should consider implementation strategies responsive to lived realities of Black women
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