Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 110
Filter
1.
Phys Rev Lett ; 131(20): 201801, 2023 Nov 17.
Article in English | MEDLINE | ID: mdl-38039482

ABSTRACT

A new dark sector antibaryon, denoted ψ_{D}, could be produced in decays of B mesons. This Letter presents a search for B^{+}→ψ_{D}+p (and the charge conjugate) decays in e^{+}e^{-} annihilations at 10.58 GeV, using data collected in the BABAR experiment. Data corresponding to an integrated luminosity of 398 fb^{-1} are analyzed. No evidence for a signal is observed. Branching fraction upper limits in the range from 10^{-7}-10^{-5} are obtained at 90% confidence level for masses of 1.0

2.
Phys Rev Lett ; 128(13): 131802, 2022 Apr 01.
Article in English | MEDLINE | ID: mdl-35426701

ABSTRACT

Axionlike particles (ALPs) are predicted in many extensions of the standard model, and their masses can naturally be well below the electroweak scale. In the presence of couplings to electroweak bosons, these particles could be emitted in flavor-changing B meson decays. We report herein a search for an ALP, a, in the reaction B^{±}→K^{±}a, a→γγ using data collected by the BABAR experiment at SLAC. No significant signal is observed, and 90% confidence level upper limits on the ALP coupling to electroweak bosons are derived as a function of ALP mass, improving current constraints by several orders of magnitude in the range 0.175 GeV

3.
Phys Rev Lett ; 128(2): 021802, 2022 Jan 14.
Article in English | MEDLINE | ID: mdl-35089770

ABSTRACT

Collider searches for dark sectors, new particles interacting only feebly with ordinary matter, have largely focused on identifying signatures of new mediators, leaving much of dark sector structures unexplored. In particular, the existence of dark matter bound states (darkonia) remains to be investigated. This possibility could arise in a simple model in which a dark photon (A^{'}) is light enough to generate an attractive force between dark fermions. We report herein a search for a J^{PC}=1^{--} darkonium state, the ϒ_{D}, produced in the reaction e^{+}e^{-}→γϒ_{D}, ϒ_{D}→A^{'}A^{'}A^{'}, where the dark photons subsequently decay into pairs of leptons or pions, using 514 fb^{-1} of data collected with the BABAR detector. No significant signal is observed, and we set bounds on the γ-A^{'} kinetic mixing as a function of the dark sector coupling constant for 0.001

4.
Phys Rev Lett ; 128(9): 091804, 2022 Mar 04.
Article in English | MEDLINE | ID: mdl-35302790

ABSTRACT

We report on the first search for electron-muon lepton flavor violation (LFV) in the decay of a b quark and b antiquark bound state. We look for the LFV decay ϒ(3S)→e^{±}µ^{∓} in a sample of 118 million ϒ(3S) mesons from 27 fb^{-1} of data collected with the BABAR detector at the SLAC PEP-II e^{+}e^{-} collider operating with a 10.36 GeV center-of-mass energy. No evidence for a signal is found, and we set a limit on the branching fraction B[ϒ(3S)→e^{±}µ^{∓}]<3.6×10^{-7} at 90% C. L. This result can be interpreted as a limit Λ_{NP}/g_{NP}^{2}>80 TeV on the energy scale Λ_{NP} divided by the coupling-squared g_{NP}^{2} of relevant new physics (NP).

5.
Phys Rev Lett ; 125(24): 241801, 2020 Dec 11.
Article in English | MEDLINE | ID: mdl-33412062

ABSTRACT

We report on a precision measurement of the ratio R_{τµ}^{ϒ(3S)}=B(ϒ(3S)→τ^{+}τ^{-})/B(ϒ(3S)→µ^{+}µ^{-}) using data collected with the BABAR detector at the SLAC PEP-II e^{+}e^{-} collider. The measurement is based on a 28 fb^{-1} data sample collected at a center-of-mass energy of 10.355 GeV corresponding to a sample of 122 million ϒ(3S) mesons. The ratio is measured to be R_{τµ}^{ϒ(3S)}=0.966±0.008_{stat}±0.014_{syst} and is in agreement with the standard model prediction of 0.9948 within 2 standard deviations. The uncertainty in R_{τµ}^{ϒ(3S)} is almost an order of magnitude smaller than the only previous measurement.

6.
Phys Rev Lett ; 125(18): 181801, 2020 Oct 30.
Article in English | MEDLINE | ID: mdl-33196250

ABSTRACT

Many scenarios of physics beyond the standard model predict the existence of new gauge singlets, which might be substantially lighter than the weak scale. The experimental constraints on additional scalars with masses in the MeV to GeV range could be significantly weakened if they interact predominantly with leptons rather than quarks. At an e^{+}e^{-} collider, such a leptophilic scalar (ϕ_{L}) would be produced predominantly through radiation from a τ lepton. We report herein a search for e^{+}e^{-}→τ^{+}τ^{-}ϕ_{L}, ϕ_{L}→ℓ^{+}ℓ^{-} (ℓ=e, µ) using data collected by the BABAR experiment at SLAC. No significant signal is observed, and we set limits on the ϕ_{L} coupling to leptons in the range 0.04

7.
Phys Rev Lett ; 124(7): 071802, 2020 Feb 21.
Article in English | MEDLINE | ID: mdl-32142319

ABSTRACT

We present a search for nine lepton-number-violating and three lepton-flavor-violating neutral charm decays of the type D^{0}→h^{'-}h^{-}ℓ^{'+}ℓ^{+} and D^{0}→h^{'-}h^{+}ℓ^{'±}ℓ^{∓}, where h and h^{'} represent a K or π meson and ℓ and ℓ^{'} an electron or muon. The analysis is based on 468 fb^{-1} of e^{+}e^{-} annihilation data collected at or close to the ϒ(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory. No significant signal is observed for any of the twelve modes, and we establish 90% confidence level upper limits on the branching fractions in the range (1.0-30.6)×10^{-7}. The limits are between 1 and 3 orders of magnitude more stringent than previous measurements.

8.
Phys Rev Lett ; 124(15): 152001, 2020 Apr 17.
Article in English | MEDLINE | ID: mdl-32357020

ABSTRACT

A study of the two-body decays B^{±}→X_{cc[over ¯]}K^{±}, where X_{cc[over ¯]} refers to one charmonium state, is reported by the BABAR Collaboration using a data sample of 424 fb^{-1}. The absolute determination of branching fractions for these decays are significantly improved compared to previous BABAR measurements. Evidence is found for the decay B^{+}→X(3872)K^{+} at the 3σ level. The absolute branching fraction B[B^{+}→X(3872)K^{+}]=[2.1±0.6(stat)±0.3(syst)]×10^{-4} is measured for the first time. It follows that B[X(3872)→J/ψπ^{+}π^{-}]=(4.1±1.3)%, supporting the hypothesis of a molecular component for this resonance.

9.
Phys Rev Lett ; 123(9): 091801, 2019 Aug 30.
Article in English | MEDLINE | ID: mdl-31524470

ABSTRACT

An angular analysis of the decay B[over ¯]→D^{*}ℓ^{-}ν[over ¯]_{ℓ}, ℓ∈{e,µ}, is reported using the full e^{+}e^{-} collision data set collected by the BABAR experiment at the ϒ(4S) resonance. One B meson from the ϒ(4S)→BB[over ¯] decay is fully reconstructed in a hadronic decay mode, which constrains the kinematics and provides a determination of the neutrino momentum vector. The kinematics of the semileptonic decay is described by the dilepton mass squared, q^{2}, and three angles. The first unbinned fit to the full four-dimensional decay rate in the standard model is performed in the so-called Boyd-Grinstein-Lebed approach, which employs a generic q^{2} parametrization of the underlying form factors based on crossing symmetry, analyticity, and QCD dispersion relations for the amplitudes. A fit using the more model-dependent Caprini-Lellouch-Neubert (CLN) approach is performed as well. Our form factor shapes show deviations from previous fits based on the CLN parametrization. The latest form factors also provide an updated prediction for the branching fraction ratio R(D^{*})≡B(B[over ¯]→D^{*}τ^{-}ν[over ¯]_{τ})/B(B[over ¯]→D^{*}ℓ^{-}ν[over ¯]_{ℓ})=0.253±0.005. Finally, using the well-measured branching fraction for the B[over ¯]→D^{*}ℓ^{-}ν[over ¯]_{ℓ} decay, a value of |V_{cb}|=(38.36±0.90)×10^{-3} is obtained that is consistent with the current world average for exclusive B[over ¯]→D^{(*)}ℓ^{-}ν[over ¯]_{ℓ} decays and remains in tension with the determination from inclusive semileptonic B decays to final states with charm.

10.
Phys Rev Lett ; 122(8): 081802, 2019 Mar 01.
Article in English | MEDLINE | ID: mdl-30932586

ABSTRACT

We report the observation of the rare charm decay D^{0}→K^{-}π^{+}e^{+}e^{-}, based on 468 fb^{-1} of e^{+}e^{-} annihilation data collected at or close to the center-of-mass energy of the ϒ(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory. We find the branching fraction in the invariant mass range 0.675

11.
Phys Rev Lett ; 122(7): 072002, 2019 Feb 22.
Article in English | MEDLINE | ID: mdl-30848619

ABSTRACT

Recent investigations have suggested that the six-quark combination uuddss could be a deeply bound state (S) that has eluded detection so far, and a potential dark matter candidate. We report the first search for a stable, doubly strange six-quark state in ϒ→SΛ[over ¯]Λ[over ¯] decays based on a sample of 90×10^{6}ϒ(2S) and 110×10^{6}ϒ(3S) decays collected by the BABAR experiment. No signal is observed, and 90% confidence level limits on the combined ϒ(2S,3S)→SΛ[over ¯]Λ[over ¯] branching fraction in the range (1.2-1.4)×10^{-7} are derived for m_{S}<2.05 GeV. These bounds set stringent limits on the existence of such exotic particles.

12.
Phys Rev Lett ; 119(13): 131804, 2017 Sep 29.
Article in English | MEDLINE | ID: mdl-29341718

ABSTRACT

We search for single-photon events in 53 fb^{-1} of e^{+}e^{-} collision data collected with the BABAR detector at the PEP-II B-Factory. We look for events with a single high-energy photon and a large missing momentum and energy, consistent with production of a spin-1 particle A^{'} through the process e^{+}e^{-}→γA^{'}; A^{'}→invisible. Such particles, referred to as "dark photons," are motivated by theories applying a U(1) gauge symmetry to dark matter. We find no evidence for such processes and set 90% confidence level upper limits on the coupling strength of A^{'} to e^{+}e^{-} in the mass range m_{A^{'}}≤8 GeV. In particular, our limits exclude the values of the A^{'} coupling suggested by the dark-photon interpretation of the muon (g-2)_{µ} anomaly, as well as a broad range of parameters for the dark-sector models.

13.
Phys Rev Lett ; 119(20): 202003, 2017 Nov 17.
Article in English | MEDLINE | ID: mdl-29219353

ABSTRACT

We measure the mass difference, Δm_{+}, between the D^{*}(2010)^{+} and the D^{+} using the decay chain D^{*}(2010)^{+}→D^{+}π^{0} with D^{+}→K^{-}π^{+}π^{+}. The data were recorded with the BABAR detector at center-of-mass energies at and near the ϒ(4S) resonance, and correspond to an integrated luminosity of approximately 468 fb^{-1}. We measure Δm_{+}=(140 601.0±6.8[stat]±12.9[syst]) keV. We combine this result with a previous BABAR measurement of Δm_{0}≡m(D^{*}(2010)^{+})-m(D^{0}) to obtain Δm_{D}=m(D^{+})-m(D^{0})=(4824.9±6.8[stat]±12.9[syst]) keV. These results are compatible with and approximately five times more precise than the Particle Data Group averages.

14.
Pediatr Diabetes ; 17(7): 483-491, 2016 11.
Article in English | MEDLINE | ID: mdl-26530288

ABSTRACT

BACKGROUND: Diabetes education of patients and/or parents is an essential part of diabetes care with effects on diabetes outcome. The objective of our study was to describe the current practice of diabetes education in Germany and Austria with regard to training frequency, patient age, migration background and diabetes therapy in a large cohort of pediatric patients with diabetes mellitus type 1 (T1DM). METHODS: We analyzed data from pediatric T1DM patients with diabetes training in 2013 and complete data available for treatment year in the multicenter Diabetes Patienten Verlaufsdokumentation (DPV) registry using sas 9.4. RESULTS: In 2013 21 871 pediatric patients with T1DM were documented [52.4% male, age: 12.70 (9.35-15.30) yr (median (interquartile range)], diabetes duration: 3.80 (1.45-7.00) yr, migration background: 21.4%, twice daily injections: 5.5%, multiple daily injections: 52.5%, insulin-pump therapy: 42%. Of these 32.31% were trained in 2013. Younger patients and their parents were trained more intensely and more frequently as inpatients compared with older patients (0-6 vs. 6-12 and 12-18 yr: teaching units: 13.07 vs. 12.05 and 9.79; inpatient: 79% vs. 72% and 70%). There was also a difference in training frequency with regard to migration background. Severe hypoglycemia or ketoacidosis resulted in intensification of training (4.0 vs. 2.0%; 7.8 vs. 3.1%). Centre-specific education tools were used frequently alone or in combination with published, standardized education programs. CONCLUSION: Training frequency was highest in younger patients and during the first year of diabetes. Acute complications resulted in more frequent diabetes training, indicating that currently many education sessions take place in consequence to these complications.


Subject(s)
Diabetes Mellitus, Type 1/therapy , Patient Education as Topic/methods , Patient Education as Topic/statistics & numerical data , Practice Patterns, Physicians'/statistics & numerical data , Adolescent , Austria/epidemiology , Child , Databases, Factual , Diabetes Complications/prevention & control , Diabetes Mellitus, Type 1/complications , Diabetes Mellitus, Type 1/epidemiology , Diabetic Ketoacidosis/epidemiology , Female , Germany/epidemiology , Humans , Hypertension/epidemiology , Male , Practice Patterns, Physicians'/trends , Registries
15.
BMC Evol Biol ; 15: 151, 2015 Aug 05.
Article in English | MEDLINE | ID: mdl-26243538

ABSTRACT

BACKGROUND: Mollusca is an extremely diverse animal phylum that includes the aculiferans (worm-like aplacophorans and eight-shelled polyplacophorans) and their sister group, the conchiferans, comprising monoplacophorans, bivalves (clams, mussels), gastropods (snails, slugs), scaphopods (tusk shells) and cephalopods (squids, octopuses). Studies on mollusks have revealed an overall number of 11 Hox genes in seven out of eight molluscan "class"-level taxa, but expression data of key developmental regulators such as homeotic genes are only available for three gastropod and two cephalopod species. These show that Hox genes are involved in the formation of specific features including shell, foot, funnel or tentacles and not in antero-posterior body plan patterning as in most other bilaterian animals. The role of Hox genes in non-conchiferan (i.e., aculiferan) mollusks remains entirely unknown. RESULTS: Here we present the first data on the expression of seven Hox genes in apolyplacophoran mollusk, Acanthochitona crinita. In A. crinita the Hox genes Acr-Hox1-5, Hox7 and Post2 are expressed in a co-linear pattern along the antero-posterior axis, but not in molluscan-specific features such as the shell or the foot. The expression pattern is restricted to the post-trochal region and the transcripts are present in ecto-, endo- and mesodermal cell layers. Contrary to the situation in gastropods and cephalopods, we did neither find Hox gene expression in distinct neural subsets of A. crinita, nor in its developing shell plates. CONCLUSIONS: Our analysis and comparison with other lophotrochozoans indicate that the basal role of Hox genes is in antero-posterior axis patterning in mollusks, similar to the vast majority of bilaterian animals, and that this role has been conserved in polyplacophorans, while co-option into patterning of evolutionary novelties emerged either at the base of Conchifera or independently in gastropods and cephalopods. These morphological innovations most likely contributed to the evolutionary success of its representatives, as exemplified by, e.g., the wide ecological range and species richness of gastropods.


Subject(s)
Evolution, Molecular , Gastropoda/genetics , Homeodomain Proteins/genetics , Mollusca/genetics , Amino Acid Sequence , Animals , Body Patterning , Gastropoda/classification , Homeodomain Proteins/chemistry , Molecular Sequence Data , Mollusca/classification , Mollusca/growth & development , Phylogeny , Sequence Alignment
16.
Diabet Med ; 32(8): 1036-50, 2015 Aug.
Article in English | MEDLINE | ID: mdl-25510978

ABSTRACT

AIMS: Improving glycaemic control in people with Type 1 diabetes is known to reduce complications. Our aim was to compare glycaemic control among people with Type 1 diabetes using data gathered in regional or national registries. METHODS: Data were obtained for children and/or adults with Type 1 diabetes from the following countries (or regions): Western Australia, Austria, Denmark, England, Champagne-Ardenne (France), Germany, Epirus, Thessaly and Thessaloniki (Greece), Galway (Ireland), several Italian regions, Latvia, Rotterdam (The Netherlands), Otago (New Zealand), Norway, Northern Ireland, Scotland, Sweden, Volyn (Ukraine), USA and Wales) from population or clinic-based registries. The sample size with available data varied from 355 to 173 880. Proportions with HbA1c < 58 mmol/mol (< 7.5%) and ≥ 75 mmol/mol (≥ 9.0%) were compared by age and sex. RESULTS: Data were available for 324 501 people. The proportions with HbA1c 58 mmol/mol (< 7.5%) varied from 15.7% to 46.4% among 44 058 people aged < 15 years, from 8.9% to 49.5% among 50 766 people aged 15-24 years and from 20.5% to 53.6% among 229 677 people aged ≥ 25 years. Sex differences in glycaemic control were small. Proportions of people using insulin pumps varied between the 12 sources with data available. CONCLUSION: These results suggest that there are substantial variations in glycaemic control among people with Type 1 diabetes between the data sources and that there is room for improvement in all populations, especially in young adults.


Subject(s)
Diabetes Mellitus, Type 1/drug therapy , Glycated Hemoglobin/metabolism , Hypoglycemic Agents/therapeutic use , Insulin Infusion Systems/statistics & numerical data , Insulin/therapeutic use , Registries , Adolescent , Adult , Austria , Denmark , Diabetes Mellitus, Type 1/metabolism , England , Female , France , Germany , Greece , Guideline Adherence , Humans , Ireland , Italy , Latvia , Male , Netherlands , New Zealand , Northern Ireland , Norway , Practice Guidelines as Topic , Scotland , Sweden , Ukraine , United States , Wales , Western Australia , Young Adult
17.
Clin Immunol ; 149(1): 133-41, 2013 Oct.
Article in English | MEDLINE | ID: mdl-23973892

ABSTRACT

X-linked inhibitor of apoptosis (XIAP) deficiency caused by mutations in BIRC4 was initially described in patients with X-linked lymphoproliferative syndrome (XLP) who had no mutations in SH2D1A. In the initial reports, EBV-associated hemophagocytic lymphohistiocytosis (HLH) was the predominant clinical phenotype. Among 25 symptomatic patients diagnosed with XIAP deficiency, we identified 17 patients who initially presented with manifestations other than HLH. These included Crohn-like bowel disease (n=6), severe infectious mononucleosis (n=4), isolated splenomegaly (n=3), uveitis (n=1), periodic fever (n=1), fistulating skin abscesses (n=1) and severe Giardia enteritis (n=1). Subsequent manifestations included celiac-like disease, antibody deficiency, splenomegaly and partial HLH. Screening by flow cytometry identified 14 of 17 patients in our cohort. However, neither genotype nor protein expression nor results from cell death studies were clearly associated with the clinical phenotype. Only mutation analysis can reliably identify affected patients. XIAP deficiency must be considered in a wide range of clinical presentations.


Subject(s)
Immunologic Deficiency Syndromes/genetics , Lymphohistiocytosis, Hemophagocytic/genetics , X-Linked Inhibitor of Apoptosis Protein/deficiency , Adolescent , Adult , Child , Child, Preschool , Genotype , Humans , Immunologic Deficiency Syndromes/immunology , Lymphohistiocytosis, Hemophagocytic/immunology , Male , Mutation , Natural Killer T-Cells/immunology , Phenotype , X-Linked Inhibitor of Apoptosis Protein/genetics , X-Linked Inhibitor of Apoptosis Protein/immunology , Young Adult
18.
Diabetologia ; 55(6): 1633-40, 2012 Jun.
Article in English | MEDLINE | ID: mdl-22366881

ABSTRACT

AIMS/HYPOTHESIS: Deterioration of microvascular function may have an early onset in individuals with type 1 diabetes mellitus. We hypothesised that microvascular autoregulation is impaired in children with type 1 diabetes and can be detected non-invasively by postocclusive reactive hyperaemia (PORH). METHODS: Microvascular autoregulation was assessed in 58 children with type 1 diabetes and 58 age- and sex-matched healthy controls by PORH using laser Doppler fluxmetry. Baseline perfusion, biological zero (defined as a 'no flow' laser Doppler signal during suprasystolic occlusion), peak perfusion following occlusion, time to peak and recovery time (time until baseline perfusion is resumed) were recorded and compared between the groups. RESULTS: Peak perfusion was higher in children with type 1 diabetes than in healthy controls (1.7 ± 0.93 AU [arbitrary units] vs 1.29 ± 0.46 AU; p = 0.004), and biological zero was lower in children with type 1 diabetes vs controls (0.14 ± 0.04 AU vs 0.19 ± 0.04 AU; p < 0.0001). No differences were seen between the groups in baseline perfusion, time to peak during PORH and recovery time following PORH. CONCLUSIONS/INTERPRETATION: PORH reveals impaired microvascular autoregulation in children with type 1 diabetes. The higher peak perfusion might reflect a decline in the vasoconstrictive ability of arteriolar smooth muscle cells upstream of capillary beds in children with type 1 diabetes.


Subject(s)
Homeostasis/physiology , Microcirculation/physiology , Adolescent , Case-Control Studies , Child , Diabetes Mellitus, Type 1/physiopathology , Female , Humans , Laser-Doppler Flowmetry , Male
19.
Clin Lab ; 58(11-12): 1153-64, 2012.
Article in English | MEDLINE | ID: mdl-23289184

ABSTRACT

BACKGROUND: Uterine leiomyomas are the most common benign tumours in women, which arise from smooth muscle cells of the uterine myometrium and usually are multicentric. In spite of their frequency pathogenesis is widely unknown, mainly due to the absence of a suitable model system. We describe the systematic optimization of culturing leiomyoma tissue explants in an economical and effective ex vivo system. METHODS: Different concentrations of oxygen, different media, sera, hormones, and growth factor supplements were tested. Immunohistochemical stainings with antibodies against hormone receptors as well as specifying proliferation and apoptotic indices and real-time PCR were performed. RESULTS: Main parameters for culturing myoma tissue explants were tested for finding an optimal protocol. Standard medium D-MEM-F12 in combination with the use of horse serum in a reduced concentration of 1% turned out to be optimal for these tissue cultures as well as the addition of estradiol and epidermal growth factor EGF to media. Reduced oxygen content in the incubator air showed no positive effect. CONCLUSIONS: For culturing tissue explants of uterine leiomyoma several conditions were optimized. The established tissue culture model allows examining the effects of known and potential therapeutic substances and the influence of immune competent cells in the process of tumour formation to find new targets for medical treatment.


Subject(s)
Leiomyoma/pathology , Uterine Neoplasms/pathology , Culture Media , Epidermal Growth Factor/administration & dosage , Estradiol/administration & dosage , Female , Humans , Immunohistochemistry , Progesterone/administration & dosage , RNA, Messenger/genetics , Real-Time Polymerase Chain Reaction
20.
HNO ; 60(10): 856-61, 2012 Oct.
Article in German | MEDLINE | ID: mdl-23052232

ABSTRACT

Conchal bowl recession often plays a significant part in the overall success of incisionless otoplasty. Performing the appropriate pinna surgery is dependent on recognizing both a patient's antihelical fold and the conchal bowl problems. If either problem is undertreated then there may be a less than ideal cosmetic outcome. For ideal outcomes, subtle conchal bowl problems must be recognized and treated for cosmesis and stability of the correction. This paper will review the most effective technique for performing incisionless conchal bowl recession.


Subject(s)
Ear, External/surgery , Minimally Invasive Surgical Procedures/methods , Otologic Surgical Procedures/methods , Plastic Surgery Procedures/methods , Humans
SELECTION OF CITATIONS
SEARCH DETAIL