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Primeur weekly 2019-07-22

Focus

EuroHPC Research and Innovation calls open July 25 with a total budget of 95 million euro ...

Quantum computing

Limitation exposed in promising quantum computing material ...

Bristol awarded GBP 8,4 million to strengthen quantum research programmes ...

Researchers build transistor-like gate for quantum information processing - with qudits ...

Fujitsu harnesses Quantum-inspired Digital Annealer technology to optimize output efficiency in power generation for renewable energy devices ...

Quantum photonics by serendipity ...

Focus on Europe

Hungary joins Italian pre-exascale EuroHPC consortium ...

Middleware

SUSE joins the iRODS Consortium ...

Hardware

NSF awards $10 million to SDSC to deploy 'Expanse' supercomputer ...

GRC announces licensing agreement with Nihon Form Services to tailor GRC's data centre immersion cooling technology for the Japanese market ...

High Performance Computing (HPC) arrives at the Edge of Space ...

Arm Flexible Access gives chip designers the freedom to experiment and test before they invest ...

Supermicro brings unprecedented performance and configurability to the intelligent edge for new security, 5G, and AI solutions ...

SwiftStack joins NVIDIA Partner Network ...

Intel and SAP broaden their technology partnership to power enterprises' digital transformation ...

The Pittsburgh Supercomputing Center to host Bridges-2 supercomputers at Next Tier Connect ...

Applications

HPC4Energy Innovation Programme announces first awards for public/private partnerships ...

Atos orchestrates AURAGEN's genomic sequencing calculation solution ...

Who's using Argonne's user facilities? ...

Predicting material properties with quantum Monte Carlo ...

NERSC hosts first 'GPUs for Science' Workshop ...

First Corones Award goes to NERSC computer scientist ...

HPC4Manufacturing project aims at improving thin-film processes used in LED lights ...

Dirty bomb simulator prepares responders ...

LHC experiments present new results on rare Higgs phenomena at 2019 EPS-HEP conference ...

RIT professor honoured with Presidential Early Career Award for Scientists and Engineers ...

A graphene superconductor that plays more than one tune ...

The Cloud

Atos becomes a Microsoft Azure Expert Managed Service Provider (MSP) ...

LHC experiments present new results on rare Higgs phenomena at 2019 EPS-HEP conference


Candidates for a Higgs produced with a Z. ATLAS (l): both decay ultimately to leptons, leaving two electrons (green) and four muons (red). CMS (r): the Higgs decays to two charm quarks forming jets (cones); the Z decays to electrons (green). Image: ATLAS/CMS/CERN.
15 Jul 2019 Ghent - At the 2019 European Physical Society's High-Energy Physics conference (EPS-HEP) taking place in Ghent, Belgium, the ATLAS and CMS collaborations presented a suite of new results. These include several analyses using the full dataset from the second run of CERN's Large Hadron Collider (LHC), recorded at a collision energy of 13TeV between 2015 and 2018. Among the highlights are the latest precision measurements involving the Higgs boson. In only seven years since its discovery, scientists have carefully studied several of the properties of this unique particle, which is increasingly becoming a powerful tool in the search for new physics.
An event recorded by ATLAS showing a candidate for a Higgs boson produced in association with two top quarks. The Higgs boson decays to four muons (red tracks). There is an additional electron (green track) and four particle jets (yellow cones). Image: ATLAS/CERN.

The results include new searches for transformations (or "decays") of the Higgs boson into pairs of muons and into pairs of charm quarks. Both ATLAS and CMS also measured previously unexplored properties of decays of the Higgs boson that involve electroweak bosons - the W, the Z and the photon - and compared these with the predictions of the Standard Model (SM) of particle physics. ATLAS and CMS will continue these studies over the course of the LHC's Run3 - 2021 to 2023 - and in the era of the High-Luminosity LHC - from 2026 onwards.

The Higgs boson is the quantum manifestation of the all-pervading Higgs field, which gives mass to elementary particles it interacts with, via the Brout-Englert-Higgs mechanism. Scientists look for such interactions between the Higgs boson and elementary particles, either by studying specific decays of the Higgs boson or by searching for instances where the Higgs boson is produced along with other particles. The Higgs boson decays almost instantly after being produced in the LHC and it is by looking through its decay products that scientists can probe its behaviour.

In the LHC's Run1 (2010 to 2012), decays of the Higgs boson involving pairs of electroweak bosons were observed. Now, the complete Run2 dataset - around 140 inverse femtobarns each, the equivalent of over 10000 trillion collisions - provides a much larger sample of Higgs bosons to study, allowing measurements of the particle's properties to be made with unprecedented precision. ATLAS and CMS have measured the so-called "differential cross-sections" of the bosonic decay processes, which look at not just the production rate of Higgs bosons but also the distribution and orientation of the decay products relative to the colliding proton beams. These measurements provide insight into the underlying mechanism that produces the Higgs bosons. Both collaborations determined that the observed rates and distributions are compatible with those predicted by the Standard Model, at the current rate of statistical uncertainty.

Since the strength of the Higgs boson's interaction is proportional to the mass of elementary particles, it interacts most strongly with the heaviest generation of fermions, the third. Previously, ATLAS and CMS had each observed these interactions. However, interactions with the lighter second-generation fermions - muons, charm quarks and strange quarks - are considerably rarer. At EPS-HEP, both collaborations reported on their searches for the elusive second-generation interactions.

ATLAS presented their first result from searches for Higgs bosons decaying to pairs of muons (H --> µµ) with the full Run2 dataset. This search is complicated by the large background of more typical SM processes that produce pairs of muons. "This result shows that we are now close to the sensitivity required to test the Standard Model's predictions for this very rare decay of the Higgs boson", stated Karl Jakobs, the ATLAS spokesperson. "However, a definitive statement on the second generation will require the larger datasets that will be provided by the LHC in Run3 and by the High-Luminosity LHC."

CMS presented their first result on searches for decays of Higgs bosons to pairs of charm quarks (H --> cc). When a Higgs boson decays into quarks, these elementary particles immediately produce jets of particles. "Identifying jets formed by charm quarks and isolating them from other types of jets is a huge challenge", stated Roberto Carlin, spokesperson for CMS. "We're very happy to have shown that we can tackle this difficult decay channel. We have developed novel machine-learning techniques to help with this task."

The Higgs boson also acts as a mediator of physics processes in which electroweak bosons scatter or bounce off each other. Studies of these processes with very high statistics serve as powerful tests of the Standard Model. ATLAS presented the first-ever measurement of the scattering of two Z bosons. Observing this scattering completes the picture for the W and Z bosons as ATLAS has previously observed the WZ scattering process and both collaborations the WW processes. CMS presented the first observation of electroweak-boson scattering that results in the production of a Z boson and a photon.

"The experiments are making big strides in the monumental task of understanding the Higgs boson", stated Eckhard Elsen, CERN's Director of Research and Computing. "After observation of its coupling to the third-generation fermions, the experiments have now shown that they have the tools at hand to address the even more challenging second generation. The LHC's precision physics programme is in full swing."

For ATLAS the following results are available:

For CMS the following results are avaiable:

An event recorded by CMS showing a candidate for a Higgs boson produced in association with two top quarks. The Higgs boson and top quarks decay leading to a final state with seven jets (orange cones), an electron (green line), a muon (red line) and missing transverse energy (pink line). Image: CMS/CERN.
Source: CERN

Back to Table of contents

Primeur weekly 2019-07-22

Focus

EuroHPC Research and Innovation calls open July 25 with a total budget of 95 million euro ...

Quantum computing

Limitation exposed in promising quantum computing material ...

Bristol awarded GBP 8,4 million to strengthen quantum research programmes ...

Researchers build transistor-like gate for quantum information processing - with qudits ...

Fujitsu harnesses Quantum-inspired Digital Annealer technology to optimize output efficiency in power generation for renewable energy devices ...

Quantum photonics by serendipity ...

Focus on Europe

Hungary joins Italian pre-exascale EuroHPC consortium ...

Middleware

SUSE joins the iRODS Consortium ...

Hardware

NSF awards $10 million to SDSC to deploy 'Expanse' supercomputer ...

GRC announces licensing agreement with Nihon Form Services to tailor GRC's data centre immersion cooling technology for the Japanese market ...

High Performance Computing (HPC) arrives at the Edge of Space ...

Arm Flexible Access gives chip designers the freedom to experiment and test before they invest ...

Supermicro brings unprecedented performance and configurability to the intelligent edge for new security, 5G, and AI solutions ...

SwiftStack joins NVIDIA Partner Network ...

Intel and SAP broaden their technology partnership to power enterprises' digital transformation ...

The Pittsburgh Supercomputing Center to host Bridges-2 supercomputers at Next Tier Connect ...

Applications

HPC4Energy Innovation Programme announces first awards for public/private partnerships ...

Atos orchestrates AURAGEN's genomic sequencing calculation solution ...

Who's using Argonne's user facilities? ...

Predicting material properties with quantum Monte Carlo ...

NERSC hosts first 'GPUs for Science' Workshop ...

First Corones Award goes to NERSC computer scientist ...

HPC4Manufacturing project aims at improving thin-film processes used in LED lights ...

Dirty bomb simulator prepares responders ...

LHC experiments present new results on rare Higgs phenomena at 2019 EPS-HEP conference ...

RIT professor honoured with Presidential Early Career Award for Scientists and Engineers ...

A graphene superconductor that plays more than one tune ...

The Cloud

Atos becomes a Microsoft Azure Expert Managed Service Provider (MSP) ...