11 research outputs found
Metastable supersymmetry breaking in N=2 non-linear sigma-models
We perform a general study of the issue of metastability for
supersymmetry-breaking vacua in theories with N=1 and N=2 global supersymmetry.
This problem turns out to capture all the important qualitative features of the
corresponding question in theories with local supersymmetry, where
gravitational effects induce only quantitative modifications. Moreover, it
allows to directly compare the conditions arising in the N=1 and N=2 cases,
since the latter becomes particular case of the former in the rigid limit. Our
strategy consists in a systematic investigation of the danger of instability
coming from the sGoldstini scalars, whose masses are entirely due to
supersymmetry breaking mass-splitting effects. We start by reviewing the
metastability conditions arising in general N=1 non-linear sigma-models with
chiral and vector multiplets. We then turn to the case of general N=2
non-linear sigma-models with hyper and vector multiplets. We first reproduce
and clarify the known no-go theorems applying to theories with only Abelian
vector multiplets and only hyper multiplets, and then derive new results
applying to more general cases. To make the comparison with N=1 models as clear
as possible, we rely on a formulation of N=2 models where one of the
supersymmetries is manifestly realized in terms of ordinary superfields,
whereas the other is realized through non-trivial transformations. We give a
self-contained account of such a construction of N=2 theories in N=1
superspace, generalizing previous work on various aspects to reach a general
and coordinate-covariant construction. We also present a direct computation of
the supertrace of the mass matrix.Comment: 50 pages, no figures; v2 minor corrections and addition of comments
and reference
Metastable supersymmetry breaking in N=2 non-linear sigma-models
Abstract We perform a general study of the issue of metastability for supersymmetrybreaking vacua in theories with N = 1 and N = 2 global supersymmetry. This problem turns out to capture all the important qualitative features of the corresponding question in theories with local supersymmetry, where gravitational effects induce only quantitative modifications. Moreover, it allows to directly compare the conditions arising in the N = 1 and N = 2 cases, since the latter becomes particular case of the former in the rigid limit. Our strategy consists in a systematic investigation of the danger of instability coming from the sGoldstini scalars, whose masses are entirely due to supersymmetry breaking mass-splitting effects. We start by reviewing the metastability conditions arising in general N = 1 non-linear sigma-models with chiral and vector multiplets. We then turn to the case of general N = 2 non-linear sigma-models with hyper and vector multiplets. We first reproduce and clarify the known no-go theorems applying to theories with only Abelian vector multiplets and only hyper multiplets, and then derive new results applying to more general cases. To make the comparison with N = 1 models as clear as possible, we rely on a formulation of N = 2 models where one of the supersymmetries is manifestly realized in terms of ordinary superfields, whereas the other is realized through non-trivial transformations. We give a self-contained account of such a construction of N = 2 theories in N = 1 superspace, generalizing previous work on various aspects to reach a general and coordinate-covariant construction. We also present a direct computation of the supertrace of the mass matrix
N=2 supersymmetry breaking at two different scales
We study N=2 spontaneous supersymmetry breaking at two different scales with
matter fields in hypermultiplets charged under the gauge group that should
involve at least two U(1) factors. Off-shell analysis is possible in the dual
single-tensor formulation of the hypermultiplets. Massless fermions can
naturally arise from pseudo-real representations of the gauge group that allow
a reformulation of the problem of chirality in N=2 theories. The above
properties are necessary ingredients towards constructing viable extensions of
the Standard Model based on N=2 supersymmetry.Comment: 26 page
Collisions Against Obstacles in Winter Sport Ski Areas
International audienceIntroduction—Collisions against obstacles (CAOs) on ski areas account for a large proportion ofdeaths of skiers and snowboarders but are poorly documented. We aimed to characterize the risk factorsand injuries of CAOs and to compare occurrences of CAOs with 2 control groups.Methods—Between 2015 and 2019 in France, data were collected on the injured population by skiarea doctors and ski patrollers. Systematic counts were also made to describe the noninjured populationon ski slopes. Cases (CAOs injured: 3391 victims) were compared with 2 controls (non-CAOs injured:198,302 victims and the noninjured population: 121,227 people). Crude and adjusted logistic regressionswere performed (P<0.05).Results—Males, highly skilled participants, skiers, and people aged <26 y had higher risks of beinginjured after a CAO than a non-CAO. Moreover, CAOs more frequently occurred off-slopes and on veryeasy slopes; lifts were more often involved. Injuries to the head and neck and trunk were more likely tooccur after CAOs than non-CAOs. Medical helicopters were more often used for CAOs than non-CAOs.Compared with the noninjured population, no age, sex, or sport group appeared clearly at risk of CAOs.Conclusions—Typical victims of CAOs are males, skiers, young people, and highly skilled participants.This population was previously identified for moving fast on the slopes and having risk-seekingbehavior, putting them at risk of high-energy accidents. There is a need for adequate prevention, such asawareness campaigns, and protection, such as individual device and padding on obstacles, that focus onprotecting against injuries to the head, neck, and trunk
In high grade ovarian carcinoma, platinum-sensitive tumor recurrence and acquired-resistance derive from quiescent residual cancer cells that overexpress CRYAB, CEACAM6 and SOX2
International audienceMost High-Grade Ovarian Carcinomas (HGOCs) are sensitive to carboplatin (CBP)-based chemotherapy but frequently recur within 24 months. Recurrent tumors remain CBP-sensitive and acquire resistance only after several treatment rounds. Recurrences arise from a small number of residual tumor cells hardly amenable to investigation in patients. We developed Patient-Derived Xenografts (PDXs) that allow the study of these different stages of CBP-sensitive recurrence and acquisition of resistance. We generated PDX models from CBP-sensitive and intrinsically resistant HGOC. PDXs were CBP- or mock-treated and tumors were sampled, after treatment and at recurrence. We also isolated models with acquired-resistance from CBP-sensitive PDXs. All tumors were characterized at the histological and transcriptome levels. PDX models reproduced treatment response seen in the patients. CBP-sensitive residual tumors contained non-proliferating tumor cells clusters embedded in a fibrotic mesh. In non-treated PDX tumors and treated CBP-resistant tumors fibrotic tissue was not prevalent. Residual tumors had marked differences in gene expression when compared to naïve and recurrent tumors, indicating downregulation of cell cycle and proliferation and upregulation of interferon response and epithelial-mesenchymal transition. This gene expression pattern resembled that described in embryonal diapause and 'drug-tolerant persister' states. Residual and acquired-resistance tumors share the overexpression of three genes: CEACAM6, CRYAB, and SOX2.Immunostaining analysis showed strong CEACAM6, CRYAB, and SOX2 protein expression in CBP-sensitive residual and acquired resistance PDX, thus, confirming RNA profiling results. In HGOC PDX, CBP-sensitive recurrences arise from a small population of quiescent, drug-tolerant, residual cells embedded in a fibrotic mesh. These cells overexpress CEACAM6, CRYAB and SOX2, whose overexpression is also associated with acquired resistance and poor patient prognosis. CEACAM6, CRYAB and SOX2 may, thus, serve as a biomarker to predict recurrence and emergence of resistant disease in CBP-treated HGOC patients
Short- and long-term results of total vs subtotal thyroidectomies in the surgical treatment of Graves' disease
Approximately one out of five patients with Graves' disease (GD) undergoes a thyroidectomy after a mean period of 18 months of medical treatment. This retrospective and non-randomized study from a teaching hospital compares short- and long-term results of total (TT) and subtotal thyroidectomies (ST) for this disease