6,200 research outputs found
On the electroweak phase transition in the Minimal Supersymmetric Standard Model
We study the finite-temperature effective potential of the Minimal
Supersymmetric Standard Model, in the limit of only one light Higgs boson.
Because of the large top Yukawa coupling, there can be significant differences
with respect to the Standard Model case: for given values of the Higgs and top
masses, little supersymmetry breaking in the stop sector can make the phase
transition more strongly first-order. After including the full structure of the
stop mass matrix, the most important experimental constraints and the leading
plasma effects, we find that the present limits on Higgs and squark masses are
still compatible with the scenario of electroweak baryogenesis, in a small
region of parameter space corresponding to m_h \simlt 70 \gev and \msba
\simlt 105 \gev.Comment: 10 A4 pages, 7 figures available upon request, CERN-TH.6833/93,
IEM-FT-69/93 (one paragraph expanded for clarity
Expectations of rehabilitation following lower limb amputation: a qualitative study.
To explore the expectations of patients about to undergo prosthetic rehabilitation following a lower limb amputation
The Gauging of Five-dimensional, N=2 Maxwell-Einstein Supergravity Theories coupled to Tensor Multiplets
We study the general gaugings of N=2 Maxwell-Einstein supergravity theories
(MESGT) in five dimensions, extending and generalizing previous work. The
global symmetries of these theories are of the form SU(2)_R X G, where SU(2)_R
is the R-symmetry group of the N=2 Poincare superalgebra and G is the group of
isometries of the scalar manifold that extend to symmetries of the full action.
We first gauge a subgroup K of G by turning some of the vector fields into
gauge fields of K while dualizing the remaining vector fields into tensor
fields transforming in a non-trivial representation of K. Surprisingly, we find
that the presence of tensor fields transforming non-trivially under the
Yang-Mills gauge group leads to the introduction of a potential which does not
admit an AdS ground state. Next we give the simultaneous gauging of the U(1)_R
subgroup of SU(2)_R and a subgroup K of G in the presence of K-charged tensor
multiplets. The potential introduced by the simultaneous gauging is the sum of
the potentials introduced by gauging K and U(1)_R separately. We present a list
of possible gauge groups K and the corresponding representations of tensor
fields. For the exceptional supergravity we find that one can gauge the SO^*(6)
subgroup of the isometry group E_{6(-26)} of the scalar manifold if one
dualizes 12 of the vector fields to tensor fields just as in the gauged N=8
supergravity.Comment: Latex file, 23 page
Influenza and respiratory syncytial virus infections in British Hajj pilgrims
Viral respiratory infections including influenza and respiratory syncytial virus (RSV) have been reported during the Hajj among international pilgrims. To help establish the burden of these infections at the Hajj, we set up a study to confirm these diagnoses in symptomatic British pilgrims who attended the 2005 Hajj. UK pilgrims with symptoms of upper respiratory tract infection (URTI) were invited to participate; after taking medical history, nasal swabs were collected for point-of-care testing (PoCT) of influenza and for subsequent PCR analysis for influenza and RSV. Of the 205 patients recruited, 37 (18%) were positive for either influenza or RSV. Influenza A (H3) accounted for 54% (20/37) of the virus-positive samples, followed by RSV 24% (9/37), influenza B 19% (7/37), and influenza A (H1) 3% (1/37). Of the influenza-positive cases, 29% (8/28) had recently had a flu immunisation. Influenza was more common in those who gave a history of contact with a pilgrim with a respiratory illness than those who did not (17 versus 9%). The overall rate of RSV was 4% (9/202). This study confirms that influenza and RSV cause acute respiratory infections in British Hajj pilgrims. Continuing surveillance and a programme of interventions to contain the spread of infection are needed at the Hajj, particularly when the world is preparing for an influenza pandemic
Vacuum Stability, Perturbativity, and Scalar Singlet Dark Matter
We analyze the one-loop vacuum stability and perturbativity bounds on a
singlet extension of the Standard Model (SM) scalar sector containing a scalar
dark matter candidate. We show that the presence of the singlet-doublet quartic
interaction relaxes the vacuum stability lower bound on the SM Higgs mass as a
function of the cutoff and lowers the corresponding upper bound based on
perturbativity considerations. We also find that vacuum stability requirements
may place a lower bound on the singlet dark matter mass for given singlet
quartic self coupling, leading to restrictions on the parameter space
consistent with the observed relic density. We argue that discovery of a light
singlet scalar dark matter particle could provide indirect information on the
singlet quartic self-coupling.Comment: 25 pages, 10 figures; v2 - fixed minor typos; v3 - added to text
discussions of other references, changed coloring of figures for easier black
and white viewin
Effects of ocean acidification on invertebrate settlement at volcanic CO<inf>2</inf> vents
We present the first study of the effects of ocean acidification on settlement of benthic invertebrates and microfauna. Artificial collectors were placed for 1 month along pH gradients at CO2 vents off Ischia (Tyrrhenian Sea, Italy). Seventy-nine taxa were identified from six main taxonomic groups (foraminiferans, nematodes, polychaetes, molluscs, crustaceans and chaetognaths). Calcareous foraminiferans, serpulid polychaetes, gastropods and bivalves showed highly significant reductions in recruitment to the collectors as pCO2 rose from normal (336-341 ppm, pH 8.09-8.15) to high levels (886-5,148 ppm) causing acidified conditions near the vents (pH 7.08-7.79). Only the syllid polychaete Syllis prolifera had higher abundances at the most acidified station, although a wide range of polychaetes and small crustaceans was able to settle and survive under these conditions. A few taxa (Amphiglena mediterranea, Leptochelia dubia, Caprella acanthifera) were particularly abundant at stations acidified by intermediate amounts of CO2 (pH 7. 41-7.99). These results show that increased levels of CO2 can profoundly affect the settlement of a wide range of benthic organisms. © 2010 Springer-Verlag
Non-resonant leptogenesis in seesaw models with an almost conserved B-L
We review the motivations and some results on leptogenesis in seesaw models
with an almost conserved lepton number. The paper is based on a talk given at
the 5th International Symposium on Symmetries in Subatomic Physics, SSP2012.Comment: 8 pages, 1 figure. Published in the proceedings of the 5th
International Symposium on Symmetries in Subatomic Physics, SSP201
Time to go global: a consultation on global health competencies for postgraduate doctors
BACKGROUND: Globalisation is having profound impacts on health and healthcare. We solicited the views of a wide range of stakeholders in order to develop core global health competencies for postgraduate doctors. METHODS: Published literature and existing curricula informed writing of seven global health competencies for consultation. A modified policy Delphi involved an online survey and face-to-face and telephone interviews over three rounds. RESULTS: Over 250 stakeholders participated, including doctors, other health professionals, policymakers and members of the public from all continents of the world. Participants indicated that global health competence is essential for postgraduate doctors and other health professionals. Concerns were expressed about overburdening curricula and identifying what is 'essential' for whom. Conflicting perspectives emerged about the importance and relevance of different global health topics. Five core competencies were developed: (1) diversity, human rights and ethics; (2) environmental, social and economic determinants of health; (3) global epidemiology; (4) global health governance; and (5) health systems and health professionals. CONCLUSIONS: Global health can bring important perspectives to postgraduate curricula, enhancing the ability of doctors to provide quality care. These global health competencies require tailoring to meet different trainees' needs and facilitate their incorporation into curricula. Healthcare and global health are ever-changing; therefore, the competencies will need to be regularly reviewed and updated
Lepton flavour violation in the MSSM
We derive new constraints on the quantities delta_{XY}^{ij}, X,Y=L,R, which
parametrise the flavour-off-diagonal terms of the charged slepton mass matrix
in the MSSM. Considering mass and anomalous magnetic moment of the electron we
obtain the bound |delta^{13}_{LL} delta^{13}_{RR}|<0.1 for tan beta=50, which
involves the poorly constrained element delta^{13}_{RR}. We improve the
predictions for the decays tau -> mu gamma, tau -> e gamma and mu -> e gamma by
including two-loop corrections which are enhanced if tan beta is large. The
finite renormalisation of the PMNS matrix from soft SUSY-breaking terms is
derived and applied to the charged-Higgs-lepton vertex. We find that the
experimental bound on BR(tau -> e gamma) severely limits the size of the MSSM
loop correction to the PMNS element U_{e3}, which is important for the proper
interpretation of a future U_{e3} measurement. Subsequently we confront our new
values for delta^{ij}_{LL} with a GUT analysis. Further, we include the effects
of dimension-5 Yukawa terms, which are needed to fix the Yukawa unification of
the first two generations. If universal supersymmetry breaking occurs above the
GUT scale, we find the flavour structure of the dimension-5 Yukawa couplings
tightly constrained by mu -> e gamma.Comment: 37 pages, 15 figures; typo in Equation (35) and (49) correcte
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