314 research outputs found
Inelastic Dark Matter and the SABRE Experiment
We present here the sensitivity of the SABRE (Sodium iodide with Active
Background REjection) experiment to benchmark proto-philic, spin dependent,
Inelastic Dark Matter models previously proposed due to their lowered tension
with existing experimental results. We perform fits to cross section, mass, and
mass splitting values to find the best fit to DAMA/LIBRA data for these models.
In this analysis, we consider the Standard Halo Model (SHM), as well as an
interesting extension upon it, the SHM+Stream distribution, to investigate the
influence of the Dark Matter velocity distribution upon experimental
sensitivity and whether or not its consideration may be able to help relieve
the present experimental tension. Based on our analysis, SABRE should be
sensitive to all the three benchmark models within 3-5 years of data taking.Comment: Adjusted for full DAMA run 1+2 efficiency. Updated to match published
versio
Unitarisation of EFT Amplitudes for Dark Matter Searches at the LHC
We propose a new approach to the LHC dark matter search analysis within the
effective field theory (EFT) framework by utilising the K-matrix unitarisation
formalism. This approach provides a reasonable estimate of the dark matter
production cross section at high energies, and hence allows reliable bounds to
be placed on the cut-off scale of relevant operators without running into the
problem of perturbative unitarity violation. We exemplify this procedure for
the effective operator D5 in monojet dark matter searches in the collinear
approximation. We compare our bounds to those obtained using the truncation
method and identify a parameter region where the unitarisation prescription
leads to more stringent bounds.Comment: 20 pages, 7 figures. References added and minor corrections made to
match published versio
Setting limits on Effective Field Theories: the case of Dark Matter
The usage of Effective Field Theories (EFT) for LHC new physics searches is
receiving increasing attention. It is thus important to clarify all the aspects
related with the applicability of the EFT formalism in the LHC environment,
where the large available energy can produce reactions that overcome the
maximal range of validity, i.e. the cutoff, of the theory. We show that this
does forbid to set rigorous limits on the EFT parameter space through a
modified version of the ordinary binned likelihood hypothesis test, which we
design and validate. Our limit-setting strategy can be carried on in its
full-fledged form by the LHC experimental collaborations, or performed
externally to the collaborations, through the Simplified Likelihood approach,
by relying on certain approximations. We apply it to the recent CMS mono-jet
analysis and derive limits on a Dark Matter (DM) EFT model. DM is selected as a
case study because the limited reach on the DM production EFT Wilson
coefficient and the structure of the theory suggests that the cutoff might be
dangerously low, well within the LHC reach. However our strategy can also be
applied to EFT's parametrising the indirect effects of heavy new physics in the
Electroweak and Higgs sectors
First bite syndrome as presenting symptom of parapharyngeal adenoid cystic carcinoma.
First bite syndrome refers to the development of pain in the parotid region after the first bite of each meal.A man was referred to our institution with first bite syndrome as his only symptom. Magnetic resonance imaging of the head and neck revealed a deep lobe parotid mass in close contact with the external carotid artery. Computed tomography guided fine needle biopsy indicated adenoid cystic carcinoma. Total parotidectomy was performed, with en bloc resection of the infiltrated external carotid artery and a selective neck dissection of levels Ib to III. High-weight ion radiotherapy was administered post-operatively.First bite syndrome has hitherto only been described following parapharyngeal space surgery. We present the first case of parotid gland adenoid cystic carcinoma presenting with first bite syndrome as the only symptom. The presence of first bite syndrome should prompt the clinician to investigate the parapharyngeal space and deep lobe of the parotid gland, especially in the absence of other signs or symptoms
Dissection with harmonic scalpel versus cold instruments in parotid surgery.
The harmonic scalpel (HS) has been used successfully in several head and neck surgical procedures. Some authors highlighted its advantages in reducing operative time, blood loss, and damages to surrounding tissue. In our study, we compared the results obtained during parotidectomy using the HS with the traditional approach to determine the benefits of the HS.130 patients with benign parotid tumors were enrolled and randomized into two groups for this prospective study. 63 patients underwent HS parotidectomy, and 67 patients received a parotidectomy using cold instruments and bipolar electrocautery hemostatic control (CI). 20 HS and 2 CI patients did not meet the inclusion criteria requirements, and were excluded.The admission time was significantly shorter in the HS group than the CI group (3.9 ± 1.2 days and 4.7 ± 1.4 days, respectively, p < 0.01). In the early post-operative period, 84\% of HS patients and 60\% of CI cases showed no facial nerve impairment (p = 0.01). Significantly more CI patients than HS patients showed the onset of Frey's syndrome (29\% and 9\%, respectively, p = 0.01). Multivariate stepwise regression analysis confirmed the reduction in admission length (Odds Ratio (OR): 0.62; p = 0.02) and the lower risk of Frey's syndrome (OR: 0.29; p = 0.04) in HS compared to CI parotidectomies.In parotid surgery, the HS is useful in preventing Frey's syndrome and reducing early transitory facial nerve dysfunction and admission times, and results in decreased medical costs and increased quality of life
Fistola faringocutanea dopo laringectomia totale: analisi dei fattori di rischio, della prognosi e delle modalitĂ di trattamento
In questo studio sono state valutate l’incidenza, i fattori di rischio e le modalità di trattamento in pazienti con fistola faringocutanea dopo laringectomia totale primaria e di salvataggio. Nel periodo compreso tra gennaio 1999 e ottobre 2014, 352 pazienti affetti da carcinoma squamocellulare della laringe sono stati sottoposti a laringectomia totale. Il decosro postoperatorio di 86 pazienti è stato complicato dall’insorgenza di fistola fainrogcutanea. Questi sono stati comparati in uno studio caso-controllo con 86 pazienti selezionati tramite software, fra quelli che non avevano sviluppato la fistola salivare. L’incidenza globale di fistola dopo laringectomia totale è stata del 24,4%, rispettivamente abbiamo registrato incidenze del 19,0%, del 28,6% e del 30,3% dopo laringectomia totale primaria, dopo radioterapia e dopo radiochemioterapia. L’analisi multivariata ha rivelato che per ipoalbuminemia ≤3,5 g/dL, per pregressa radioterapia e radiochemioterapia il rischio relativo di sviluppo di fistola è stato rispettivamente 2,47, 3,09 e 7,69. In caso di laringectomia totale di salvataggio abbiamo registrato una comparsa precoce della fistola entro i primi 10 giorni postoperatori. Le modalità di trattamento della fistola faringocutanea sono risultate essere significativamente differenti in caso di laringectomia totale primaria, dopo radioterapia e dopo radiochemioterapia. Infatti, mentre nel primo caso è stato sufficiente un trattamento di tipo conservativo (93,55%), dopo chemioradioterapia ha prevalso il ricorso a tecniche chirurgiche ricostruttive con lembi regionali (58,82%). Nel caso dei pazienti radiotrattati, le opzioni terapeutiche della fistola sono risultate essere equamente distribuite tra quella medica, eventualmente con l’aggiunta dell’ossigenoterapia iperbarica, e quella chirurgica ricostruttiva. La conoscenza dei fattori di rischio soggettivi e il loro valore prognostico, permettono al chirurgo di pianificare le strategie preventive al fine di ridurre il rischio di formazione della complicanza e, conseguentemente, dei tempi di degenza e dei relativi costi
On the Validity of the Effective Field Theory for Dark Matter Searches at the LHC Part III: Analysis for the t-channel
We extend our recent analysis of the limitations of the effective field theory approach to studying dark matter at the LHC, by investigating the case in which Dirac dark matter couples to standard model quarks via t-channel exchange of a heavy scalar mediator. We provide analytical results for the validity of the effective field theory description, for both 1as = 8 TeV and 14 TeV. We make use of a MonteCarlo event generator to assess the validity of our analytical conclusions. We also point out the general trend that in the regions where the effective field theory is valid, the dark matter relic abundance is typically large
The absolute age of the globular cluster M15 using near-infrared adaptive optics images from PISCES/LBT
We present deep near-infrared (NIR) J, Ks photometry of the old, metal-poor
Galactic globular cluster M\,15 obtained with images collected with the LUCI1
and PISCES cameras available at the Large Binocular Telescope (LBT). We show
how the use of First Light Adaptive Optics system coupled with the (FLAO)
PISCES camera allows us to improve the limiting magnitude by ~2 mag in Ks. By
analyzing archival HST data, we demonstrate that the quality of the LBT/PISCES
color magnitude diagram is fully comparable with analogous space-based data.
The smaller field of view is balanced by the shorter exposure time required to
reach a similar photometric limit. We investigated the absolute age of M\,15 by
means of two methods: i) by determining the age from the position of the main
sequence turn-off; and ii) by the magnitude difference between the MSTO and the
well-defined knee detected along the faint portion of the MS. We derive
consistent values of the absolute age of M15, that is 12.9+-2.6 Gyr and
13.3+-1.1 Gyr, respectively.Comment: 13 pages, 8 figures, ApJ accepte
Less-simplified models of dark matter for direct detection and the LHC
We construct models of dark matter with suppressed spin-independent scattering cross section utilizing the existing simplified model framework. Even simple combinations of simplified models can exhibit interference effects that cause the tree level contribution to the scattering cross section to vanish, thus demonstrating that direct detection limits on simplified models are not robust when embedded in a more complicated and realistic framework. In general for fermionic WIMP masses ≳ 10 GeV direct detection limits on the spin-independent scattering cross section are much stronger than those coming from the LHC. However these model combinations, which we call less-simplified models, represent situations where LHC searches become more competitive than direct detection experiments even for moderate dark matter mass. We show that a complementary use of several searches at the LHC can strongly constrain the direct detection blind spots by setting limits on the coupling constants and mediators’ mass. We derive the strongest limits for combinations of vector + scalar, vector + “squark”, and “squark” + scalar mediator, and present the corresponding projections for the LHC 14 TeV for a number of searches: mono-jet, jets + missing energy, and searches for heavy vector resonances
Recommendations of the LHC Dark Matter Working Group: Comparing LHC searches for heavy mediators of dark matter production in visible and invisible decay channels
Weakly-coupled TeV-scale particles may mediate the interactions between
normal matter and dark matter. If so, the LHC would produce dark matter through
these mediators, leading to the familiar "mono-X" search signatures, but the
mediators would also produce signals without missing momentum via the same
vertices involved in their production. This document from the LHC Dark Matter
Working Group suggests how to compare searches for these two types of signals
in case of vector and axial-vector mediators, based on a workshop that took
place on September 19/20, 2016 and subsequent discussions. These suggestions
include how to extend the spin-1 mediated simplified models already in
widespread use to include lepton couplings. This document also provides
analytic calculations of the relic density in the simplified models and reports
an issue that arose when ATLAS and CMS first began to use preliminary numerical
calculations of the dark matter relic density in these models.Comment: 19 pages, 4 figures; v2: author list and LaTeX problem fixe
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