1,429 research outputs found
The Minimal Scale Invariant Extension of the Standard Model
We perform a systematic analysis of an extension of the Standard Model that
includes a complex singlet scalar field and is scale invariant at the tree
level. We call such a model the Minimal Scale Invariant extension of the
Standard Model (MSISM). The tree-level scale invariance of the model is
explicitly broken by quantum corrections, which can trigger electroweak
symmetry breaking and potentially provide a mechanism for solving the gauge
hierarchy problem. Even though the scale invariant Standard Model is not a
realistic scenario, the addition of a complex singlet scalar field may result
in a perturbative and phenomenologically viable theory. We present a complete
classification of the flat directions which may occur in the classical scalar
potential of the MSISM. After calculating the one-loop effective potential of
the MSISM, we investigate a number of representative scenarios and determine
their scalar boson mass spectra, as well as their perturbatively allowed
parameter space compatible with electroweak precision data. We discuss the
phenomenological implications of these scenarios, in particular, whether they
realize explicit or spontaneous CP violation, neutrino masses or provide dark
matter candidates. In particular, we find a new minimal scale-invariant model
of maximal spontaneous CP violation which can stay perturbative up to
Planck-mass energy scales, without introducing an unnaturally large hierarchy
in the scalar-potential couplings.Comment: 71 pages, 34 eps figures, numerical error corrected, clarifying
comments adde
Experimental and Theoretical Challenges in the Search for the Quark Gluon Plasma: The STAR Collaboration's Critical Assessment of the Evidence from RHIC Collisions
We review the most important experimental results from the first three years
of nucleus-nucleus collision studies at RHIC, with emphasis on results from the
STAR experiment, and we assess their interpretation and comparison to theory.
The theory-experiment comparison suggests that central Au+Au collisions at RHIC
produce dense, rapidly thermalizing matter characterized by: (1) initial energy
densities above the critical values predicted by lattice QCD for establishment
of a Quark-Gluon Plasma (QGP); (2) nearly ideal fluid flow, marked by
constituent interactions of very short mean free path, established most
probably at a stage preceding hadron formation; and (3) opacity to jets. Many
of the observations are consistent with models incorporating QGP formation in
the early collision stages, and have not found ready explanation in a hadronic
framework. However, the measurements themselves do not yet establish
unequivocal evidence for a transition to this new form of matter. The
theoretical treatment of the collision evolution, despite impressive successes,
invokes a suite of distinct models, degrees of freedom and assumptions of as
yet unknown quantitative consequence. We pose a set of important open
questions, and suggest additional measurements, at least some of which should
be addressed in order to establish a compelling basis to conclude definitively
that thermalized, deconfined quark-gluon matter has been produced at RHIC.Comment: 101 pages, 37 figures; revised version to Nucl. Phys.
The same ELA class II risk factors confer equine insect bite hypersensitivity in two distinct populations
Insect bite hypersensitivity (IBH) is a chronic allergic dermatitis common in horses. Affected horses mainly react against antigens present in the saliva from the biting midges, Culicoides ssp, and occasionally black flies, Simulium ssp. Because of this insect dependency, the disease is clearly seasonal and prevalence varies between geographical locations. For two distinct horse breeds, we genotyped four microsatellite markers positioned within the MHC class II region and sequenced the highly polymorphic exons two from DRA and DRB3, respectively. Initially, 94 IBH-affected and 93 unaffected Swedish born Icelandic horses were tested for genetic association. These horses had previously been genotyped on the Illumina Equine SNP50 BeadChip, which made it possible to ensure that our study did not suffer from the effects of stratification. The second population consisted of 106 unaffected and 80 IBH-affected Exmoor ponies. We show that variants in the MHC class II region are associated with disease susceptibility (praw = 2.34 × 10−5), with the same allele (COR112:274) associated in two separate populations. In addition, we combined microsatellite and sequencing data in order to investigate the pattern of homozygosity and show that homozygosity across the entire MHC class II region is associated with a higher risk of developing IBH (p = 0.0013). To our knowledge this is the first time in any atopic dermatitis suffering species, including man, where the same risk allele has been identified in two distinct populations
Gabapentin for chronic pelvic pain in women (GaPP2):a multicentre, randomised, double-blind, placebo-controlled trial
BackgroundChronic pelvic pain affects 2–24% of women worldwide and evidence for medical treatments is scarce. Gabapentin is effective in treating some chronic pain conditions. We aimed to measure the efficacy and safety of gabapentin in women with chronic pelvic pain and no obvious pelvic pathology.MethodsWe performed a multicentre, randomised, double-blind, placebo-controlled randomised trial in 39 UK hospital centres. Eligible participants were women with chronic pelvic pain (with or without dysmenorrhoea or dyspareunia) of at least 3 months duration. Inclusion criteria were 18–50 years of age, use or willingness to use contraception to avoid pregnancy, and no obvious pelvic pathology at laparoscopy, which must have taken place at least 2 weeks before consent but less than 36 months previously. Participants were randomly assigned in a 1:1 ratio to receive gabapentin (titrated to a maximum dose of 2700 mg daily) or matching placebo for 16 weeks. The online randomisation system minimised allocations by presence or absence of dysmenorrhoea, psychological distress, current use of hormonal contraceptives, and hospital centre. The appearance, route, and administration of the assigned intervention were identical in both groups. Patients, clinicians, and research staff were unaware of the trial group assignments throughout the trial. Participants were unmasked once they had provided all outcome data at week 16–17, or sooner if a serious adverse event requiring knowledge of the study drug occurred. The dual primary outcome measures were worst and average pain scores assessed separately on a numerical rating scale in weeks 13–16 after randomisation, in the intention-to-treat population. Self-reported adverse events were assessed according to intention-to-treat principles. This trial is registered with the ISRCTN registry, ISCRTN77451762.FindingsParticipants were screened between Nov 30, 2015, and March 6, 2019, and 306 were randomly assigned (153 to gabapentin and 153 to placebo). There were no significant between-group differences in both worst and average numerical rating scale (NRS) pain scores at 13–16 weeks after randomisation. The mean worst NRS pain score was 7·1 (standard deviation [SD] 2·6) in the gabapentin group and 7·4 (SD 2·2) in the placebo group. Mean change from baseline was −1·4 (SD 2·3) in the gabapentin group and −1·2 (SD 2·1) in the placebo group (adjusted mean difference −0·20 [97·5% CI −0·81 to 0·42]; p=0·47). The mean average NRS pain score was 4·3 (SD 2·3) in the gabapentin group and 4·5 (SD 2·2) in the placebo group. Mean change from baseline was −1·1 (SD 2·0) in the gabapentin group and −0·9 (SD 1·8) in the placebo group (adjusted mean difference −0·18 [97·5% CI −0·71 to 0·35]; p=0·45). More women had a serious adverse event in the gabapentin group than in the placebo group (10 [7%] of 153 in the gabapentin group compared with 3 [2%] of 153 in the placebo group; p=0·04). Dizziness, drowsiness, and visual disturbances were more common in the gabapentin group.InterpretationThis study was adequately powered, but treatment with gabapentin did not result in significantly lower pain scores in women with chronic pelvic pain, and was associated with higher rates of side-effects than placebo. Given the increasing reports of abuse and evidence of potential harms associated with gabapentin use, it is important that clinicians consider alternative treatment options to off-label gabapentin for the management of chronic pelvic pain and no obvious pelvic pathology.FundingNational Institute for Health Research
Spin effects in the antler event topology at hadron colliders
We investigate spin correlation effects in the "antler" event topology pp->
A-> B1, B2 -> l^{-}, C1, l^{+}, C2 at the LHC. We study the shapes of several
kinematic variables, including the relative pseudorapidity, relative azimuthal
angle and the energies of the two leptons, as well as several mass variables
M_{ll}, Meff, \sqrt{s}_{min}, MT2, MCT and MCTx. We focus on the two kinematic
extremes of \sqrt{s} - threshold and infinity - and derive analytical
expressions for the differential distributions of several variables, most
notably the cos{\theta_{ll}}^* variable proposed by Barr in hep-ph/0511115. For
all possible spin assignments of particles A, B and C, we derive the
cos{\theta_{ll}}^* differential distribution at threshold, including the
effects of spin correlations. Our analytical results help identify the
problematic cases for spin discrimination.Comment: 43 pages, 14 figures, Preprint typeset in JHEP styl
GLI1 Confers Profound Phenotypic Changes upon LNCaP Prostate Cancer Cells That Include the Acquisition of a Hormone Independent State
The GLI (GLI1/GLI2) transcription factors have been implicated in the development
and progression of prostate cancer although our understanding of how they
actually contribute to the biology of these common tumours is limited. We
observed that GLI reporter activity was higher in normal (PNT-2) and
tumourigenic (DU145 and PC-3) androgen-independent cells compared to
androgen-dependent LNCaP prostate cancer cells and, accordingly, GLI mRNA levels
were also elevated. Ectopic expression of GLI1 or the constitutively active
ΔNGLI2 mutant induced a distinct cobblestone-like morphology in LNCaP cells
that, regarding the former, correlated with increased GLI2 as well as expression
of the basal/stem-like markers CD44, β1-integrin, ΔNp63 and BMI1, and
decreased expression of the luminal marker AR (androgen receptor). LNCaP-GLI1
cells were viable in the presence of the AR inhibitor bicalutamide and gene
expression profiling revealed that the transcriptome of LNCaP-GLI1 cells was
significantly closer to DU145 and PC-3 cells than to control LNCaP-pBP (empty
vector) cells, as well as identifying LCN2/NGAL as a highly induced transcript
which is associated with hormone independence in breast and prostate cancer.
Functionally, LNCaP-GLI1 cells displayed greater clonal growth and were more
invasive than control cells but they did not form colonies in soft agar or
prostaspheres in suspension suggesting that they do not possess inherent stem
cell properties. Moreover, targeted suppression of GLI1 or GLI2 with siRNA did
not reverse the transformed phenotype of LNCaP-GLI1 cells nor did double
GLI1/GLI2 knockdowns activate AR expression in DU145 or PC-3 cells. As such,
early targeting of the GLI oncoproteins may hinder progression to a hormone
independent state but a more detailed understanding of the mechanisms that
maintain this phenotype is required to determine if their inhibition will
enhance the efficacy of anti-hormonal therapy through the induction of a luminal
phenotype and increased dependency upon AR function
Contribution of higher risk genes and European admixture to Crohnʼs disease in African Americans:
African Americans (AA) are an admixed population of West African (WA) and European ancestry (EA). Crohn's disease (CD) susceptibility genes have not been established. We therefore evaluated the contribution of European admixture and major established risk genes to AA CD
Multiple novel prostate cancer susceptibility signals identified by fine-mapping of known risk loci among Europeans
Genome-wide association studies (GWAS) have identified numerous common prostate cancer (PrCa) susceptibility loci. We have
fine-mapped 64 GWAS regions known at the conclusion of the iCOGS study using large-scale genotyping and imputation in
25 723 PrCa cases and 26 274 controls of European ancestry. We detected evidence for multiple independent signals at 16
regions, 12 of which contained additional newly identified significant associations. A single signal comprising a spectrum of
correlated variation was observed at 39 regions; 35 of which are now described by a novel more significantly associated lead SNP,
while the originally reported variant remained as the lead SNP only in 4 regions. We also confirmed two association signals in
Europeans that had been previously reported only in East-Asian GWAS. Based on statistical evidence and linkage disequilibrium
(LD) structure, we have curated and narrowed down the list of the most likely candidate causal variants for each region.
Functional annotation using data from ENCODE filtered for PrCa cell lines and eQTL analysis demonstrated significant
enrichment for overlap with bio-features within this set. By incorporating the novel risk variants identified here alongside the
refined data for existing association signals, we estimate that these loci now explain ∼38.9% of the familial relative risk of PrCa,
an 8.9% improvement over the previously reported GWAS tag SNPs. This suggests that a significant fraction of the heritability of
PrCa may have been hidden during the discovery phase of GWAS, in particular due to the presence of multiple independent
signals within the same regio
Research campaign : macroscopic quantum resonators (MAQRO)
The objective of the proposed macroscopic quantum resonators (MAQRO) mission is to harness space for achieving long free-fall times, extreme vacuum, nano-gravity, and cryogenic temperatures to test the foundations of physics in macroscopic quantum experiments at the interface with gravity. Developing the necessary technologies, achieving the required sensitivities and providing the necessary isolation of macroscopic quantum systems from their environment will lay the path for developing novel quantum sensors. Earlier studies showed that the proposal is feasible but that several critical challenges remain, and key technologies need to be developed. Recent scientific and technological developments since the original proposal of MAQRO promise the potential for achieving additional science objectives. The proposed research campaign aims to advance the state of the art and to perform the first macroscopic quantum experiments in space. Experiments on the ground, in micro-gravity, and in space will drive the proposed research campaign during the current decade to enable the implementation of MAQRO within the subsequent decade
QCD and strongly coupled gauge theories : challenges and perspectives
We highlight the progress, current status, and open challenges of QCD-driven physics, in theory and in experiment. We discuss how the strong interaction is intimately connected to a broad sweep of physical problems, in settings ranging from astrophysics and cosmology to strongly coupled, complex systems in particle and condensed-matter physics, as well as to searches for physics beyond the Standard Model. We also discuss how success in describing the strong interaction impacts other fields, and, in turn, how such subjects can impact studies of the strong interaction. In the course of the work we offer a perspective on the many research streams which flow into and out of QCD, as well as a vision for future developments.Peer reviewe
- …