39 research outputs found
Heavy Dark Matter Through the Higgs Portal
Motivated by Higgs Portal and Hidden Valley models, heavy particle dark
matter that communicates with the supersymmetric Standard Model via pure Higgs
sector interactions is considered. We show that a thermal relic abundance
consistent with the measured density of dark matter is possible for masses up
to \sim 30\tev. For dark matter masses above \sim 1\tev, non-perturbative
Sommerfeld corrections to the annihilation rate are large, and have the
potential to greatly affect indirect detection signals. For large dark matter
masses, the Higgs-dark-matter-sector couplings are large and we show how such
models may be given a UV completion within the context of so-called "Fat-Higgs"
models. Higgs Portal dark matter provides an example of an attractive
alternative to conventional MSSM neutralino dark matter that may evade
discovery at the LHC, while still being within the reach of current and
upcoming indirect detection experiments.Comment: LaTex, 21 pages, 9 figures. Discussion improved, comments and
references adde
Solving the cosmic lithium problems with primordial late-decaying particles
We investigate the modifications to predictions for the abundances of light
elements from standard Big-Bang nucleosynthesis when exotic late-decaying
particles with lifetimes exceeding ~1 sec are prominent in the early Universe.
Utilising a model-independent analysis of the properties of these long-lived
particles, we identify the parameter space associated with models that are
consistent with all observational data and hence resolve the much discussed
discrepancies between observations and theoretical predictions for the
abundances of Li^7 and Li^6.Comment: 6 pages, 3 figures, submitted to Physical Review D; minor changes to
reference
Difficulties for Compact Composite Object Dark Matter
It has been suggested ``that DM particles are strongly interacting composite
macroscopically large objects ... made of well known light quarks (or ...
antiquarks)." In doing so it is argued that these compact composite objects
(CCOs) are ``natural explanations of many observed data, such as [the] 511 keV
line from the bulge of our galaxy" observed by INTEGRAL and the excess of
diffuse gamma-rays in the 1-20 MeV band observed by COMPTEL. Here we argue that
the atmospheres of positrons that surround CCOs composed of di-antiquark pairs
in the favoured Colour-Flavour-Locked superconducting state are sufficiently
dense as to stringently limit the penetration of interstellar electrons
incident upon them, resulting in an extreme suppression of previously estimated
rates of positronium, and hence the flux of 511 keV photons resulting from
their decays, and also in the rate of direct electron-positron annihilations,
which yield the MeV photons proposed to explain the 1-20 MeV excess. We also
demonstrate that even if a fraction of positrons somehow penetrated to the
surface of the CCOs, the extremely strong electric fields generated from the
bulk antiquark matter would result in the destruction of positronium atoms long
before they decay.Comment: 7 Pages, 4 Figures. Major changes invoke
Heavy dark matter through the Higgs portal
Abstract Motivated by Higgs Portal and Hidden Valley models, heavy particle dark matter that communicates with the supersymmetric Standard Model via pure Higgs sector interactions is considered. We show that a thermal relic abundance consistent with the measured density of dark matter is possible for masses up to ∼ 30 TeV. For dark matter masses above ∼ 1 TeV, non-perturbative Sommerfeld corrections to the annihilation rate are large, and have the potential to greatly affect indirect detection signals. For large dark matter masses, the Higgs-dark matter sector couplings are large and we show how such models may be given a UV completion within the context of so-called "Fat-Higgs" models. Higgs Portal dark matter provides an example of an attractive alternative to conventional MSSM neutralino dark matter that may evade discovery at the LHC, while still being within the reach of current and upcoming indirect detection experiments
Pulsars as the Source of the WMAP Haze
The WMAP haze is an excess in the 22 to 93 GHz frequency bands of WMAP
extending about 10 degrees from the galactic center. We show that synchrotron
emission from electron-positron pairs injected into the interstellar medium by
the galactic population of pulsars with energies in the 1 to 100 GeV range can
explain the frequency spectrum of the WMAP haze and the drop in the average
haze power with latitude. The same spectrum of high energy electron-positron
pairs from pulsars, which gives rise to the haze, may also generate the
observed excesses in AMS, HEAT and PAMELA. We discuss the spatial morphology of
the pulsar synchrotron signal and its deviation from spherical symmetry, which
may provide an avenue to determine the pulsar contribution to the haze.Comment: 18 pages, 4 figures. Corrected errors in fig 1-3 and added discussion
of the detailed spatial morphology of the haze signa
Citizen Journalism at the Margins
Amidst burgeoning literature on citizen journalism, we still know relatively little about how and why genuinely marginalised groups seek to use this form of reporting to challenge their exclusion. In this article, we aim to address this gap by analysing two UK citizen journalism initiatives emanating from The Big Issue Foundation, a national homeless organisation, and Access Dorset, a regional charity for disabled and elderly people. These case studies are united by the authors’ involvement in both instances, primarily through designing and delivering bespoke citizen journalism education and mentoring. Based on over 40 hours of interviews with participants of the workshops and 36 hours of participant observation, we analyse the challenges participants faced in their journey to become citizen journalists. This included: low self-esteem, physical health and mental wellbeing, the need for accessible and adaptable technology, and overcoming fear associated with assuming a public voice. We also analyse marginalised groups’ attitudes to professional journalism and education, and its role in shaping journalistic identity and self-empowerment. Whilst demonstrably empowering and esteem building,our participants were acutely aware of societal power relations that were seemingly still beyond their ability to influence. Those who are marginalised are, nevertheless, in the best position to use citizen journalism as a conduit for social change, we argue - though challenges remain even at the grassroots level to foster and sustain participatory practices
A Systematic Review of the Efficacy and Toxicity of Brachytherapy Boost Combined with External Beam Radiotherapy for Nonmetastatic Prostate Cancer
CONTEXT: The optimum use of brachytherapy (BT) combined with external beam radiotherapy (EBRT) for localised/locally advanced prostate cancer (PCa) remains uncertain.OBJECTIVE: To perform a systematic review to determine the benefits and harms of EBRT-BT.EVIDENCE ACQUISITION: Ovid MEDLINE, Embase, and EBM Reviews-Cochrane Central Register of Controlled Trials databases were systematically searched for studies published between January 1, 2000 and June 7, 2022, according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. Eligible studies compared low- or high-dose-rate EBRT-BT against EBRT ± androgen deprivation therapy (ADT) and/or radical prostatectomy (RP) ± postoperative radiotherapy (RP ± EBRT). The main outcomes were biochemical progression-free survival (bPFS), severe late genitourinary (GU)/gastrointestinal toxicity, metastasis-free survival (MFS), cancer-specific survival (CSS), and overall survival (OS), at/beyond 5 yr. Risk of bias was assessed and confounding assessment was performed. A meta-analysis was performed for randomised controlled trials (RCTs).EVIDENCE SYNTHESIS: Seventy-three studies were included (two RCTs, seven prospective studies, and 64 retrospective studies). Most studies included participants with intermediate-or high-risk PCa. Most studies, including both RCTs, used ADT with EBRT-BT. Generally, EBRT-BT was associated with improved bPFS compared with EBRT, but similar MFS, CSS, and OS. A meta-analysis of the two RCTs showed superior bPFS with EBRT-BT (estimated fixed-effect hazard ratio [HR] 0.54 [95% confidence interval {CI} 0.40-0.72], p < 0.001), with absolute improvements in bPFS at 5-6 yr of 4.9-16%. However, no difference was seen for MFS (HR 0.84 [95% CI 0.53-1.28], p = 0.4) or OS (HR 0.87 [95% CI 0.63-1.19], p = 0.4). Fewer studies examined RP ± EBRT. There is an increased risk of severe late GU toxicity, especially with low-dose-rate EBRT-BT, with some evidence of increased prevalence of severe GU toxicity at 5-6 yr of 6.4-7% across the two RCTs.CONCLUSIONS: EBRT-BT can be considered for unfavourable intermediate/high-risk localised/locally advanced PCa in patients with good urinary function, although the strength of this recommendation based on the European Association of Urology guideline methodology is weak given that it is based on improvements in biochemical control.PATIENT SUMMARY: We found good evidence that radiotherapy combined with brachytherapy keeps prostate cancer controlled for longer, but it could lead to worse urinary side effects than radiotherapy without brachytherapy, and its impact on cancer spread and patient survival is less clear.</p
A Systematic Review of the Efficacy and Toxicity of Brachytherapy Boost Combined with External Beam Radiotherapy for Nonmetastatic Prostate Cancer
CONTEXT: The optimum use of brachytherapy (BT) combined with external beam radiotherapy (EBRT) for localised/locally advanced prostate cancer (PCa) remains uncertain.OBJECTIVE: To perform a systematic review to determine the benefits and harms of EBRT-BT.EVIDENCE ACQUISITION: Ovid MEDLINE, Embase, and EBM Reviews-Cochrane Central Register of Controlled Trials databases were systematically searched for studies published between January 1, 2000 and June 7, 2022, according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. Eligible studies compared low- or high-dose-rate EBRT-BT against EBRT ± androgen deprivation therapy (ADT) and/or radical prostatectomy (RP) ± postoperative radiotherapy (RP ± EBRT). The main outcomes were biochemical progression-free survival (bPFS), severe late genitourinary (GU)/gastrointestinal toxicity, metastasis-free survival (MFS), cancer-specific survival (CSS), and overall survival (OS), at/beyond 5 yr. Risk of bias was assessed and confounding assessment was performed. A meta-analysis was performed for randomised controlled trials (RCTs).EVIDENCE SYNTHESIS: Seventy-three studies were included (two RCTs, seven prospective studies, and 64 retrospective studies). Most studies included participants with intermediate-or high-risk PCa. Most studies, including both RCTs, used ADT with EBRT-BT. Generally, EBRT-BT was associated with improved bPFS compared with EBRT, but similar MFS, CSS, and OS. A meta-analysis of the two RCTs showed superior bPFS with EBRT-BT (estimated fixed-effect hazard ratio [HR] 0.54 [95% confidence interval {CI} 0.40-0.72], p < 0.001), with absolute improvements in bPFS at 5-6 yr of 4.9-16%. However, no difference was seen for MFS (HR 0.84 [95% CI 0.53-1.28], p = 0.4) or OS (HR 0.87 [95% CI 0.63-1.19], p = 0.4). Fewer studies examined RP ± EBRT. There is an increased risk of severe late GU toxicity, especially with low-dose-rate EBRT-BT, with some evidence of increased prevalence of severe GU toxicity at 5-6 yr of 6.4-7% across the two RCTs.CONCLUSIONS: EBRT-BT can be considered for unfavourable intermediate/high-risk localised/locally advanced PCa in patients with good urinary function, although the strength of this recommendation based on the European Association of Urology guideline methodology is weak given that it is based on improvements in biochemical control.PATIENT SUMMARY: We found good evidence that radiotherapy combined with brachytherapy keeps prostate cancer controlled for longer, but it could lead to worse urinary side effects than radiotherapy without brachytherapy, and its impact on cancer spread and patient survival is less clear.</p