269 research outputs found
Synergies between astroparticle, particle and nuclear physics
One overarching objective of science is to further our understanding of the
universe, from its early stages to its current state and future evolution. This
depends on gaining insight on the universe's most macroscopic components, for
example galaxies and stars, as well as describing its smallest components,
namely elementary particles and nuclei and their interactions. It is clear that
this endeavour requires combined expertise from the fields of astroparticle
physics, particle physics and nuclear physics. Pursuing common scientific
drivers also require mastering challenges related to instrumentation (e.g.
beams and detectors), data acquisition, selection and analysis, and making data
and results available to the broader science communities. Joint work and
recognition of these "foundational" topics will help all communities grow
towards their individual and common scientific goals. The talk corresponding to
this contribution has been presented during the special ECFA session of EPS-HEP
2019 focused on the update of the European Strategy of Particle Physics.Comment: Late submission to the Proceedings of the EPS-HEP 2019 Conference,
Special ECFA session (https://indico.cern.ch/event/577856/sessions/291392
Uncovering tau leptons-enriched semi-visible jets at the LHC
This Letter proposes a new signature for confining dark sectors at the Large
Hadron Collider. Under the assumption of a QCD-like hidden sector, hadronic
jets containing stable dark bound states could manifest in proton-proton
collisions. We present a simplified model with a boson yielding the
production of jets made up of dark bound states and subsequently leading to the
decays of those that are unstable to leptons and Standard Model quarks.
The resulting signature is characterised by non-isolated lepton pairs
inside semi-visible jets. We estimate the constraints on our model from
existing CMS and ATLAS analyses. We propose a set of variables that leverage
the leptonic content of the jet and exploit them in a supervised jet tagger to
enhance the signal-to-background separation. Furthermore, we discuss the
performance and limitations of current triggers for accessing sub-TeV
masses, as well as possible strategies that can be adopted by experiments to
access such low mass regions. We estimate that with the currently available
triggers, a high mass search can claim a discovery (exclusion) of
the boson with a mass up to 4.5TeV (5.5TeV) with the full Run2 data of the
LHC when the fraction of unstable dark hadrons decaying to lepton pairs
is around , and with a coupling of the to right-handed up-type
quarks of 0.25. Furthermore, we show that, with new trigger strategies for
Run3, it may be possible to access masses down to 700 GeV, for which the
event topology is still composed of two resolved semi-visible jets.Comment: 11 pages, 8 figures, 2 tables, (published on EPJ C as Letter
Simplified Models for Dark Matter and Missing Energy Searches at the LHC
The study of collision events with missing energy as searches for the dark
matter (DM) component of the Universe are an essential part of the extensive
program looking for new physics at the LHC. Given the unknown nature of DM, the
interpretation of such searches should be made broad and inclusive. This report
reviews the usage of simplified models in the interpretation of missing energy
searches. We begin with a brief discussion of the utility and limitation of the
effective field theory approach to this problem. The bulk of the report is then
devoted to several different simplified models and their signatures, including
s-channel and t-channel processes. A common feature of simplified models for DM
is the presence of additional particles that mediate the interactions between
the Standard Model and the particle that makes up DM. We consider these in
detail and emphasize the importance of their inclusion as final states in any
coherent interpretation. We also review some of the experimental progress in
the field, new signatures, and other aspects of the searches themselves. We
conclude with comments and recommendations regarding the use of simplified
models in Run-II of the LHC.Comment: v2. references added, version submitted to journal. v1. 47 pages, 13
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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
Prognostic and predictive role of EGFR pathway alterations in biliary cancer patients treated with chemotherapy and anti-EGFR
The association of anti-EGFR to gemcitabine and oxaliplatin (GEMOX) chemotherapy did not improve survival in biliary tract carcinoma (BTC) patients. Multiple mechanisms might be involved in the resistance to anti-EGFR. Here, we explored the mutation profile of EGFR extracellular domain (ECD), of tyrosine kinase domain (TKD), and its amplification status. EGFR mutational status of exons 12, 18-21 was analyzed in 57 tumors by Sanger sequencing. EGFR amplification was evaluated in 37 tumors by Fluorescent In Situ Hybridization (FISH). Kaplan-Meier curves were calculated using the log-rank test. Six patients had mutations in exon 12 of EGFR ECD and 7 in EGFR TKD. Neither EGFR ECD nor TKD mutations affected progression free survival (PFS) or overall survival (OS) in the entire population. In the panitumumab plus GEMOX (P-GEMOX) arm, ECD mutated patients had a worse OS, while EGFR TKD mutated patients had a trend towards shorter PFS and OS. Overall, the presence of mutations in EGFR or in its transducers did not affect PFS or OS, while the extrahepatic cholangiocarcinoma (ECC) mutated patients had a worse prognosis compared to WT. Nineteen out of 37 tumors were EGFR amplified, but the amplification did not correlate with survival. ECC EGFR amplified patients had improved OS, whereas the amplification significantly correlated with poor PFS (p = 0.03) in gallbladder carcinoma patients. The high molecular heterogeneity is a predominant feature of BTC: the alterations found in this work seem to have a prognostic impact rather than a predictive role towards anti-EGFR therapy
Snowmass 2021 Cross Frontier Report: Dark Matter Complementarity (Extended Version)
The fundamental nature of Dark Matter is a central theme of the Snowmass 2021
process, extending across all frontiers. In the last decade, advances in
detector technology, analysis techniques and theoretical modeling have enabled
a new generation of experiments and searches while broadening the types of
candidates we can pursue. Over the next decade, there is great potential for
discoveries that would transform our understanding of dark matter. In the
following, we outline a road map for discovery developed in collaboration among
the frontiers. A strong portfolio of experiments that delves deep, searches
wide, and harnesses the complementarity between techniques is key to tackling
this complicated problem, requiring expertise, results, and planning from all
Frontiers of the Snowmass 2021 process.Comment: v1 is first draft for community commen
HEP Community White Paper on Software trigger and event reconstruction
Realizing the physics programs of the planned and upgraded high-energy
physics (HEP) experiments over the next 10 years will require the HEP community
to address a number of challenges in the area of software and computing. For
this reason, the HEP software community has engaged in a planning process over
the past two years, with the objective of identifying and prioritizing the
research and development required to enable the next generation of HEP
detectors to fulfill their full physics potential. The aim is to produce a
Community White Paper which will describe the community strategy and a roadmap
for software and computing research and development in HEP for the 2020s. The
topics of event reconstruction and software triggers were considered by a joint
working group and are summarized together in this document.Comment: Editors Vladimir Vava Gligorov and David Lang
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