842 research outputs found
Identifying a new particle with jet substructures
We investigate a potential of measuring properties of a heavy resonance X,
exploiting jet substructure techniques. Motivated by heavy higgs boson
searches, we focus on the decays of X into a pair of (massive) electroweak
gauge bosons. More specifically, we consider a hadronic Z boson, which makes it
possible to determine properties of X at an earlier stage. For of O(1)
TeV, two quarks from a Z boson would be captured as a "merged jet" in a
significant fraction of events. The use of the merged jet enables us to
consider a Z-induced jet as a reconstructed object without any combinatorial
ambiguity. We apply a conventional jet substructure method to extract
four-momenta of subjets from a merged jet. We find that jet substructure
procedures may enhance features in some kinematic observables formed with
subjets. Subjet momenta are fed into the matrix element associated with a given
hypothesis on the nature of X, which is further processed to construct a matrix
element method (MEM)-based observable. For both moderately and highly boosted Z
bosons, we demonstrate that the MEM with current jet substructure techniques
can be a very powerful discriminator in identifying the physics nature of X. We
also discuss effects from choosing different jet sizes for merged jets and
jet-grooming parameters upon the MEM analyses.Comment: 36 pages, 11 figures, published in JHE
The 750 GeV Diphoton Excess May Not Imply a 750 GeV Resonance
We discuss non-standard interpretations of the 750 GeV diphoton excess
recently reported by the ATLAS and CMS Collaborations which do not involve a
new, relatively broad, resonance with a mass near 750 GeV. Instead, we consider
the sequential cascade decay of a much heavier, possibly quite narrow,
resonance into two photons along with one or more invisible particles. The
resulting diphoton invariant mass signal is generically rather broad, as
suggested by the data. We examine three specific event topologies - the antler,
the sandwich, and the 2-step cascade decay, and show that they all can provide
a good fit to the observed published data. In each case, we delineate the
preferred mass parameter space selected by the best fit. In spite of the
presence of invisible particles in the final state, the measured missing
transverse energy is moderate, due to its anti- correlation with the diphoton
invariant mass. We comment on the future prospects of discriminating with
higher statistics between our scenarios, as well as from more conventional
interpretations.Comment: Discussion about the ATLAS Moriond EW2016 added. Matched to PRL
accepted versio
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OPTIMASS: A Package for the Minimization of Kinematic Mass Functions with Constraints
Reconstructed mass variables, such as , , , and
, play an essential role in searches for new physics at hadron
colliders. The calculation of these variables generally involves constrained
minimization in a large parameter space, which is numerically challenging. We
provide a C++ code, OPTIMASS, which interfaces with the MINUIT library to
perform this constrained minimization using the Augmented Lagrangian Method.
The code can be applied to arbitrarily general event topologies and thus allows
the user to significantly extend the existing set of kinematic variables. We
describe this code and its physics motivation, and demonstrate its use in the
analysis of the fully leptonic decay of pair-produced top quarks using the
variables.Comment: 39 pages, 12 figures, (1) minor revision in section 3, (2) figure
added in section 4.3, (3) reference added and (4) matched with published
versio
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EFFECT OF LOW DOSE RADIATION ON DIFFERENTIATION OF BONE MARROW CELLS INTO DENDRITIC CELLS
Low dose radiation has been shown to be beneficial to living organisms using several biological systems, including immune and hematopoietic systems. Chronic low dose radiation was shown to stimulate immune systems, resulting in controlling the proliferation of cancer cells, maintain immune balance and induce hematopoietic hormesis. Since dendritic cells are differentiated from bone marrow cells and are key players in maintaining the balance between immune activation and tolerance, it may be important to further characterize whether low dose radiation can influence the capacity of bone marrow cells to differentiate into dendritic cells. We have shown that bone marrow cells from low dose- irradiated (γ-radiation, 0.2Gy, 15.44mGy/h) mice can differentiate into dendritic cells that have several different characteristics, such as expression of surface molecules, cytokine secretion and antigen uptake capacity, when compared to dentritic cells differentiated from the control bone marrow cells. These differences observed in the low dose radiation group can be beneficial to living organisms either by activation of immune responses to foreign antigens or tumors, or maintenance of self-tolerance. To the best of our knowledge, this is the first report showing that total-body low dose radiation can modulate the capacity of bone marrow cells to differentiate into dendritic cells
Insulin Secretion and Incretin Hormone Concentration in Women with Previous Gestational Diabetes Mellitus
BackgroundWe examined the change in the levels of incretin hormone and effects of glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) on insulin secretion in women with previous gestational diabetes (pGDM).MethodsA 75-g oral glucose tolerance test (OGTT) was conducted on 34 women with pGDM. In addition, 11 women with normal glucose tolerance, matched for age, height and weight, were also tested. The insulin, GIP, GLP-1, and glucagon concentrations were measured, and their anthropometric and biochemical markers were also measured.ResultsAmong 34 women with pGDM, 18 had normal glucose tolerance, 13 had impaired glucose tolerance (IGT) and 1 had diabetes. No significant differences were found in GLP-1 concentration between the pGDM and control group. However, a significantly high level of glucagon was present in the pGDM group at 30 minutes into the OGTT. The GIP concentration was elevated at 30 minutes and 60 minutes in the pGDM group. With the exception of the 30-minute timepoint, women with IGT had significantly high blood glucose from 0 to 120 minutes. However, there was no significant difference in insulin or GLP-1 concentration. The GIP level was significantly high from 0 to 90 minutes in patients diagnosed with IGT.ConclusionGLP-1 secretion does not differ between pGDM patients and normal women. GIP was elevated, but that does not seem to induce in increase in insulin secretion. Therefore, we conclude that other factors such as heredity and environment play important roles in the development of type 2 diabetes
A Surgically Treated Case of Chronic Necrotizing Aspergillosis with Pleural Invasion
Aspergillus is a ubiquitous fungus and can cause many levels of disease severity. Chronic necrotizing aspergillosis is a rare disease and few cases have been reported in Korea. We experienced a case of pleural aspergillosis that was treated successfully with medical and surgical interventions. The 52-year-old man who was diagnosed with chronic necrotizing pulmonary aspergillosis underwent surgical treatment including a lobectomy, decortication, and myoplasty. The patient was also medically treated with amphotericin B followed by voriconazole. Pleural irrigation with amphotericin B was also performed. A multi-dimensional approach should be considered for treating chronic necrotizing pulmonary aspergillosis
Reverberation Mapping of PG 0934+013 with the Southern African Large Telescope
We present the variability and time lag measurements of PG 0934+013 based on
a photometric and spectroscopic monitoring campaign over a two year period. We
obtained 46 epochs of data from the spectroscopic campaign, which was carried
out using the Southern African Large Telescope with 1 week cadence over
two sets of 4 month-long observing period, while we obtained 80 epochs of
\textit{B}-band imaging data using a few 1-m class telescopes. Due to the seven
month gap between the two observing periods, we separately measured the time
lags of broad emission lines including H, by comparing the emission line
light curve with the \textit{B}-band continuum light curve using the
cross-correlation function techniques. We determined the H lag,
days in the observed-frame based on
Year 2 data, while the time lag from Year 1 data was not reliably determined.
Using the rms spectrum of Year 2 data, we measured the \Hb\ line dispersion
\sigmaline = 668 44 \kms\ after correcting for the spectral resolution.
Adopting a virial factor f = 4.47 from Woo et al. 2015, we determined the black
hole mass M = \msun based on the
\Hb\ time lag and velocity.Comment: 13 pages, 10 figures, ApJ in pres
Pseudotumor of the Omentum Associated with Migration of the Ingested Crab-Leg
Foreign body ingestion is not uncommon in clinical practice, and it may occasionally lead to penetration injuries. Emergency physicians and radiologists sometimes fail to obtain complete histories including ingestion and may overlook the possibility of foreign body-induced complications. Herein, we report a case of stomach antrum perforation due to foreign body migration. We were unaware of the patient's history of eating the Korean delicacy "Kanjang-gaejang," which is raw crab seasoned with soy sauce. Several imaging diagnostic modalities had suggested the possibility of a malignant mass in the gastrocolic ligament area. During the operation, a crab leg was discovered as the cause of an intra-abdominal abscess. The patient underwent an antrectomy, a vagotomay, and a transverse colon wedge resection. We present this unusual case of a pseudotumorous lesion caused by ingestion of Kanjang-gaejang
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