853 research outputs found
Gaugino Anomaly Mediated SUSY Breaking: phenomenology and prospects for the LHC
We examine the supersymmetry phenomenology of a novel scenario of
supersymmetry (SUSY) breaking which we call Gaugino Anomaly Mediation, or
inoAMSB. This is suggested by recent work on the phenomenology of flux
compactified type IIB string theory. The essential features of this scenario
are that the gaugino masses are of the anomaly-mediated SUSY breaking (AMSB)
form, while scalar and trilinear soft SUSY breaking terms are highly
suppressed. Renormalization group effects yield an allowable sparticle mass
spectrum, while at the same time avoiding charged LSPs; the latter are common
in models with negligible soft scalar masses, such as no-scale or gaugino
mediation models. Since scalar and trilinear soft terms are highly suppressed,
the SUSY induced flavor and CP-violating processes are also suppressed. The
lightest SUSY particle is the neutral wino, while the heaviest is the gluino.
In this model, there should be a strong multi-jet +etmiss signal from squark
pair production at the LHC. We find a 100 fb^{-1} reach of LHC out to
m_{3/2}\sim 118 TeV, corresponding to a gluino mass of \sim 2.6 TeV. A double
mass edge from the opposite-sign/same flavor dilepton invariant mass
distribution should be visible at LHC; this, along with the presence of short--
but visible-- highly ionizing tracks from quasi-stable charginos, should
provide a smoking gun signature for inoAMSB.Comment: 30 pages including 14 .eps figure
A Human Development Framework for CO2 Reductions
Although developing countries are called to participate in CO2 emission
reduction efforts to avoid dangerous climate change, the implications of
proposed reduction schemes in human development standards of developing
countries remain a matter of debate. We show the existence of a positive and
time-dependent correlation between the Human Development Index (HDI) and per
capita CO2 emissions from fossil fuel combustion. Employing this empirical
relation, extrapolating the HDI, and using three population scenarios, the
cumulative CO2 emissions necessary for developing countries to achieve
particular HDI thresholds are assessed following a Development As Usual
approach (DAU). If current demographic and development trends are maintained,
we estimate that by 2050 around 85% of the world's population will live in
countries with high HDI (above 0.8). In particular, 300Gt of cumulative CO2
emissions between 2000 and 2050 are estimated to be necessary for the
development of 104 developing countries in the year 2000. This value represents
between 20% to 30% of previously calculated CO2 budgets limiting global warming
to 2{\deg}C. These constraints and results are incorporated into a CO2
reduction framework involving four domains of climate action for individual
countries. The framework reserves a fair emission path for developing countries
to proceed with their development by indexing country-dependent reduction rates
proportional to the HDI in order to preserve the 2{\deg}C target after a
particular development threshold is reached. Under this approach, global
cumulative emissions by 2050 are estimated to range from 850 up to 1100Gt of
CO2. These values are within the uncertainty range of emissions to limit global
temperatures to 2{\deg}C.Comment: 14 pages, 7 figures, 1 tabl
NLL soft and Coulomb resummation for squark and gluino production at the LHC
We present predictions of the total cross sections for pair production of
squarks and gluinos at the LHC, including the stop-antistop production process.
Our calculation supplements full fixed-order NLO predictions with resummation
of threshold logarithms and Coulomb singularities at next-to-leading
logarithmic (NLL) accuracy, including bound-state effects. The numerical effect
of higher-order Coulomb terms can be as big or larger than that of soft-gluon
corrections. For a selection of benchmark points accessible with data from the
2010-2012 LHC runs, resummation leads to an enhancement of the total inclusive
squark and gluino production cross section in the 15-30 % range. For individual
production processes of gluinos, the corrections can be much larger. The
theoretical uncertainty in the prediction of the hard-scattering cross sections
is typically reduced to the 10 % level.Comment: 45 pages, 16 Figures, LaTex. v2: published version. Grids with
numerical results for the NLL cross sections for squark and gluino production
at the 7/8 TeV LHC are included in the submission and are also available at
http://omnibus.uni-freiburg.de/~cs1010/susy.htm
Diagnosing Spin at the LHC via Vector Boson Fusion
We propose a new technique for determining the spin of new massive particles
that might be discovered at the Large Hadron Collider. The method relies on
pair-production of the new particles in a kinematic regime where the vector
boson fusion production mechanism is enhanced. For this regime, we show that
the distribution of the leading jets as a function of their relative azimuthal
angle can be used to distinguish spin-0 from spin-1/2 particles. We illustrate
this effect by considering the particular cases of (i) strongly-interacting,
stable particles and (ii) supersymmetric particles carrying color charge. We
argue that this method should be applicable in a wide range of new physics
scenarios.Comment: 5 pages, 4 figure
Phase appearance or disappearance in two-phase flows
This paper is devoted to the treatment of specific numerical problems which
appear when phase appearance or disappearance occurs in models of two-phase
flows. Such models have crucial importance in many industrial areas such as
nuclear power plant safety studies. In this paper, two outstanding problems are
identified: first, the loss of hyperbolicity of the system when a phase appears
or disappears and second, the lack of positivity of standard shock capturing
schemes such as the Roe scheme. After an asymptotic study of the model, this
paper proposes accurate and robust numerical methods adapted to the simulation
of phase appearance or disappearance. Polynomial solvers are developed to avoid
the use of eigenvectors which are needed in usual shock capturing schemes, and
a method based on an adaptive numerical diffusion is designed to treat the
positivity problems. An alternate method, based on the use of the hyperbolic
tangent function instead of a polynomial, is also considered. Numerical results
are presented which demonstrate the efficiency of the proposed solutions
Probing natural SUSY from stop pair production at the LHC
We consider the natural supersymmetry scenario in the framework of the
R-parity conserving minimal supersymmetric standard model (called natural MSSM)
and examine the observability of stop pair production at the LHC. We first scan
the parameters of this scenario under various experimental constraints,
including the SM-like Higgs boson mass, the indirect limits from precision
electroweak data and B-decays. Then in the allowed parameter space we study the
stop pair production at the LHC followed by the stop decay into a top quark
plus a lightest neutralino or into a bottom quark plus a chargino. From
detailed Monte Carlo simulations of the signals and backgrounds, we find the
two decay modes are complementary to each other in probing the stop pair
production, and the LHC with TeV and 100 luminosity is
capable of discovering the stop predicted in natural MSSM up to 450 GeV. If no
excess events were observed at the LHC, the 95% C.L. exclusion limits of the
stop masses can reach around 537 GeV.Comment: 19 pages, 10 figures, version accepted by JHE
The polo-like kinase 1 (PLK1) inhibitor NMS-P937 is effective in a new model of disseminated primary CD56+ acute monoblastic leukaemia
CD56 is expressed in 15–20% of acute myeloid leukaemias (AML) and is associated with extramedullary diffusion, multidrug resistance and poor prognosis. We describe the establishment and characterisation of a novel disseminated model of AML (AML-NS8), generated by injection into mice of leukaemic blasts freshly isolated from a patient with an aggressive CD56+ monoblastic AML (M5a). The model reproduced typical manifestations of this leukaemia, including presence of extramedullary masses and central nervous system involvement, and the original phenotype, karyotype and genotype of leukaemic cells were retained in vivo. Recently Polo-Like Kinase 1 (PLK1) has emerged as a new candidate drug target in AML. We therefore tested our PLK1 inhibitor NMS-P937 in this model either in the engraftment or in the established disease settings. Both schedules showed good efficacy compared to standard therapies, with a significant increase in median survival time (MST) expecially in the established disease setting (MST = 28, 36, 62 days for vehicle, cytarabine and NMS-P937, respectively). Importantly, we could also demonstrate that NMS-P937 induced specific biomarker modulation in extramedullary tissues. This new in vivo model of CD56+ AML that recapitulates the human tumour lends support for the therapeutic use of PLK1 inhibitors in AML
Two successful pregnancies in a woman with chronic myeloid leukemia exposed to nilotinib during the first trimester of her second pregnancy: case study
The occurrence of chronic myeloid leukemia in pregnancy is rare and its management poses a clinical challenge for physicians treating these patients. We report a 30-year-old woman with chronic myeloid leukemia who became pregnant twice successfully. Philadelphia-positive CML in its chronic phase was diagnosed at 16 weeks of her first gestation. At that time, she received no treatment throughout her pregnancy. At 38 weeks of gestation, a normal infant was delivered by cesarean section. At six weeks postpartum, the patient underwent imatinib mesylate therapy but she could not tolerate the treatment. The treatment was then changed to nilotinib at 400 mg orally b.i.d. Two years later, she became pregnant again while she was on nilotinib 200 mg b.i.d. The unplanned pregnancy was identified during her 7.4 weeks of gestation. Because the patient elected to continue her pregnancy, nilotinib was stopped immediately, and no further treatment was given until delivery. Neither obstetrical complications nor structural malformations in neonates in both pregnancies were observed. Both babies' growth and development have been normal. Although this experience is limited to a single patient, the success of this patient demonstrates that the management of chronic myeloid leukemia in pregnant women may be individualized based on the relative risks and benefits of the patient and fetus
Advancing Tests of Relativistic Gravity via Laser Ranging to Phobos
Phobos Laser Ranging (PLR) is a concept for a space mission designed to
advance tests of relativistic gravity in the solar system. PLR's primary
objective is to measure the curvature of space around the Sun, represented by
the Eddington parameter , with an accuracy of two parts in ,
thereby improving today's best result by two orders of magnitude. Other mission
goals include measurements of the time-rate-of-change of the gravitational
constant, and of the gravitational inverse square law at 1.5 AU
distances--with up to two orders-of-magnitude improvement for each. The science
parameters will be estimated using laser ranging measurements of the distance
between an Earth station and an active laser transponder on Phobos capable of
reaching mm-level range resolution. A transponder on Phobos sending 0.25 mJ, 10
ps pulses at 1 kHz, and receiving asynchronous 1 kHz pulses from earth via a 12
cm aperture will permit links that even at maximum range will exceed a photon
per second. A total measurement precision of 50 ps demands a few hundred
photons to average to 1 mm (3.3 ps) range precision. Existing satellite laser
ranging (SLR) facilities--with appropriate augmentation--may be able to
participate in PLR. Since Phobos' orbital period is about 8 hours, each
observatory is guaranteed visibility of the Phobos instrument every Earth day.
Given the current technology readiness level, PLR could be started in 2011 for
launch in 2016 for 3 years of science operations. We discuss the PLR's science
objectives, instrument, and mission design. We also present the details of
science simulations performed to support the mission's primary objectives.Comment: 25 pages, 10 figures, 9 table
Gluino-Squark Production at the LHC: The Threshold
An analysis of the cross section for hadronic production of gluino-squark
pairs close to threshold is presented. Within the framework of non-relativistic
QCD a significant enhancement compared to fixed order perturbation theory is
observed which originates from the characteristic remnants of the gluino-squark
resonances below the nominal pair threshold. The analysis includes all colour
configurations of S-wave gluino-squark pairs, i.e. triplet, sextet and 15
representation. Matching coefficients at leading order are separately evaluated
for all colour configurations. The dominant QCD corrections, arising from
initial- and final-state radiation are included. The non-relativistic dynamics
of the gluino pair is solved by calculating the Green's function in
Next-to-Leading Order (NLO). The results are applied to benchmark scenarios,
based on Snowmass Points and Slopes (SPS). As a consequence of the large decay
rate of at least one of the constituents squark or gluino annihilation decays
of the bound state (\tilde{g}\tilde{q})\rightarrow gq, q\gamma, qZ or q'W^{\pm}
are irrelevant. Thus the signatures of gluino-quark production below and above
the nominal threshold are identical. Numerical results for the cross section at
the Large Hadron Collider (LHC) at \sqrt{s}=7 TeV and 14 TeV are presented. The
enhancement of the total cross section through final state interaction amounts
to roughly 3%.Comment: 25 pages, 9 figures, Eq. 10 modified. Reference [30] added.
Discussion of the expected quality of the approximation added before eq. 23.
Some changes in notation. Typos correcte
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