29,324 research outputs found
Has a Higgs-flavon with a GeV mass been detected at the LHC13?
Higgs-flavon fields appear as a part of the Froggatt-Nielsen (FN) mechanism,
which attempts to explain the hierarchy of Yukawa couplings. We explore the
possibility that the 750 GeV diphoton resonance recently reported at the LHC13,
could be identified with a low-scale Higgs-flavon field and find the
region of the parameter space consistent with CMS and ATLAS data. It is found
that the extra vector-like fermions of the ultraviolet completion of the FN
mechanism are necessary in order to reproduce the observed signal. We consider
a standard model (SM) extension that contains two Higgs doublets (a standard
one and an inert one) and one complex FN singlet. The inert doublet includes a
stable neutral boson, which provides a viable dark matter candidate, while the
mixing of the standard doublet and the FN singlet induces flavor violation in
the Higgs sector at the tree-level. Constraints on the parameters of the model
are derived from the LHC Higgs data, which include the search for the lepton
flavor violating decay of the SM Higgs boson . It is also
found that in some region of the parameter space the model may give rise to a
large branching ratio for the decay, of the order of 0.1, which
could be searched for at the LHC.Comment: 18 pages, 7 Figures, includes updated files to match published
versio
Bayesian model selection for electromagnetic kaon production on the nucleon
We present the results of a Bayesian analysis of a Regge model to describe
the background contribution for K+ Lambda and K+ Sigma0 photoproduction. The
model is based on the exchange of K+(494) and K*+(892) trajectories in the
t-channel. We utilise the Bayesian evidence Z to determine the best model
variant for each channel. The Bayesian evidence integrals were calculated using
the Nested Sampling algorithm. For different prior widths, we find decisive
Bayesian evidence (\Delta ln Z ~ 24) for a K+ Lambda photoproduction Regge
model with a positive vector coupling and a negative tensor coupling constant
for the K*+(892) trajectory, and a rotating phase factor for both trajectories.
Using the chi^2 minimisation method, one could not draw this conclusion from
the same dataset. For the K+ Sigma0 photoproduction Regge model, on the other
hand, the difference between the evidence integrals is insufficient to pinpoint
one model variant.Comment: 13 pages, 4 figure
Active cleaning technique for removing contamination from optical surfaces in space
An active cleaning technique for removing contaminants from optical surfaces in space was investigated with emphasis on the feasibility of using plasma exposure as a means of in-situ cleaning. The major work accomplished includes: (1) development of an in-situ reflectometer for use in conjunction with the contaminant film deposition/cleaning facility; (2) completion of Apollo Telescope Mount (ATM) filter treatment experiments to assess the effects of plasma exposure on the UV transmittance; (3) attempts to correlate the atomic oxygen flux with cleaning rate; (4) completion of in-situ butadien contamination/plasma cleaning/UV reflectance measurement experiments; (5) carbon cleaning experiments using various gases; (6) completion of silicone contamination/cleaning experiments; and (7) experiments conducted at low chamber pressures to determine cleaning rate distribution and contamination of surfaces adjacent to those being cleaned
A bottom-up approach to the strong CP problem
The strong CP problem is one of many puzzles in the theoretical description
of elementary particle physics that still lacks an explanation. While top-down
solutions to that problem usually comprise new symmetries or fields or both, we
want to present a rather bottom-up perspective. The main problem seems to be
how to achieve small CP violation in the strong interactions despite large CP
violation in weak interactions. Observation of CP violation is exclusively
through the Higgs--Yukawa interactions. In this paper, we show that with
minimal assumptions on the structure of mass (Yukawa) matrices they do not
contribute to the strong CP problem and thus we can provide a pathway to a
solution of the strong CP problem within the structures of the Standard Model
and no extension at the electroweak scale is needed. However, to address the
flavor puzzle, models based on minimal SU(3) flavor groups leading to the
proposed flavor matrices are favored. Though we refrain from an explicit a UV
completion of the Standard Model, we provide a simple requirement those models
should have to intrinsically not show a strong CP problem.Comment: 12 pages; v2: extended discussion, title changed to be more genera
Majocchi’s Granuloma by Trichophytum rubrum in a kidney transplant patient - A case report
Introduction: Trichophytum rubrum is a filamentous fungus, with worldwide distribution, that usually causes
superficial infections of skin and nails, namely tinea pedis, tinea corporis, tinea cruris and onychomycosis.
Rarely, severe dermatophytosis can occur, presenting as deep dermatophytosis, Majocchi’s Granuloma or
extensive dermatophytosis.
Objectives and Methods: Case report of Majocchi’s Granuloma in a kidney transplant patient.
Results: A case of a 55-year-old woman who underwent a kidney transplant 7 months before, under
immunosuppressive therapy with tacrolimus and mycophenolate mofetil. She attended a Dermatology
consultation to clarify skin lesions that appeared 6 months earlier. The skin exam revealed hard and painful
plaque lesions on both legs, with an ulcer on the left leg lesion, violaceous papular lesions on the dorsum of
the left foot and toes and a hard consistency nodule on the left leg. Some of the toe nails presented dystrophy
or onycholysis. The patient denied any previous trauma or contact with plants or soil.
Biopsies of lesions of the left leg and foot dorsum where sent for histology and mycological culture and toe
nails for mycological culture. The histological examinations showed, in the reticular dermis and reaching the
hypodermis, suppurative granulomas with multinucleated giant cells and areas of necrosis. PAS (Periodic Acid-
Schiff) and GMS (Grocott’s Methenamine Silver) staining revealed multiple spores and septate hypha within the
granulomas but not in the stratum corneum. No remnants of hair follicles where found.
Culture of skin biopsies were positive for Tricophytum rubrum but nails´ culture was negative.
Identification was further confirmed by sequencing of ITS region of ribosomal DNA (GenBank accession
number MK967277).
Oral Itraconazole 100mg bid and topic Sertoconazole where initiated. The patient was observed one month
after and reported general malaise, tiredness, exertional dyspnea, whitish stools and increased abdominal
volume. The physician chose to discontinue itraconazole and initiate oral terbinafine 250mg id. After two
months on oral terbinafine, there was regression of the legs´ and left foot lesions with ulcer healing and
disappearance of the left leg nodule.
Conclusion: Diagnosis of deeper dermatophytosis is difficult, in part because there is no specific clinical
presentation and, in many cases, it is even polymorphic. However, especially in patients with
immunodeficiency, this hypothesis should be weighed. Confirmation is achieved by finding hyphae compatible
with dermatophytes in the dermis and a positive culture for a dermatophyte.
Treatment should include systemic antifungal agents, to which topical medication may be associated. Multiple
therapeutic regimens have been proposed, but randomized trials or large case series are lacking. Antifungal
therapy should be continued until the lesions are completely resolved. Surgical treatment has been reported as
an option for highly localized lesions.info:eu-repo/semantics/publishedVersio
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