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The collaboration between ATLAS and CMS is chasing the unseen with the Higgs boson

Candidate events reflect the Higgs boson obtained by the vector-boson fusion and disintegrate into invisible particles as recorded by ATLAS (left) and CMS (right). Events include pairs of jets (yellow cones) and missing energy (red or purple lines). Credit: CERN

The Higgs boson lives for an extremely short time before it transforms or “disintegrates” into other particles. It was due to the discovery of some of these decay products that the unique particle was first – and continues to be – observed during a particle collision on the Large Hadron Collider (LHC).


But what if the Higgs boson also disintegrated into unexpected new particles that were invisible to LHC detectors, such as particles that could make up dark matter penetrating the universe? A collaboration between ATLAS and CMS at the LHC has explored this possibility in two recent studies by setting new strict ceilings for the proportion of Higgs bosons that decay into invisible particles.

According to the standard model particle physicsthe Higgs boson indirectly decays into known invisible particles – almost massless particles, so-called. neutrinos– only in 0.1% of cases. However, if dark matter is made up of particles that interact too weakly to be detected, as many physicists suspect, dark matter particles can interact with the Higgs boson and, if not too massive, allow the Higgs boson to decay into it, increasing the proportion of invisible disintegrated Higgs boson.

In their latest independent research, ATLAS and CMS staff looked for invisible Higgs boson decays in proton-proton collision data collected during the LHC’s second launch. Both teams were looking for a specific type of collision in which the Higgs boson is formed as a result of a process known as a vector boson fusion and then breaks up into invisible particles.

These vector boson fusion events contain additional splashes, or “jets,” of particles released to both ends of the particle detectors, making this method of producing the Higgs boson easier to notice than other modes. Together with the “missing energy” in the collision products that invisible particles will suffer, these jets and their properties provide the hallmarks of such invisible Higgs-boson events.

ATLAS and CMS searches found no cases of these invisible Higgs boson events that would exceed the expected number of background events that mimic desired events. However, they showed that the Higgs boson cannot break down into invisible particles more often than a certain percentage of the time: 15% for ATLAS and 18% for CMS, compared to the expected percentage based on computer modeling of the standard model, 10% for both. ATLAS and CMS.

These boundaries coincide well with each other, and when interpreted in the context of dark matter models, they become the limits of the force of interaction of dark matter particles with atomic nuclei, which complement the boundaries obtained by collider-free experiments on dark matter.

As the LHC will be restarted later this year and deliver more data, ATLAS and CMS will no doubt continue to pursue the unseen through the Higgs boson.


Study of dark matter using the Higgs boson


Additional information:
Search for invisible Higgs boson decays obtained by merging vector bosons in proton and proton collisions at s√ = 13 TeV, arXiv: 2201.11585 [hep-ex] arxiv.org/abs/2201.11585

Search for invisible Higgs boson decays in events with vector-boson fusion signatures using 139 fb-1 proton-proton data recorded by the ATLAS experiment, arXiv: 2202.07953 [hep-ex] arxiv.org/abs/2202.07953

Citation: ATLAS and CMS collaboration in pursuit of the unseen with the Higgs boson (2022, February 24), obtained February 24, 2022 from https://phys.org/news/2022-02-atlas-cms-collaborations-invisible- higgs.html

This document is subject to copyright. Except for any honest transaction for the purpose of private study or research, no part may be reproduced without written permission. The content is provided for informational purposes only.



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The collaboration between ATLAS and CMS is chasing the unseen with the Higgs boson

Candidate events reflect the Higgs boson obtained by the vector-boson fusion and disintegrate into invisible particles as recorded by ATLAS (left) and CMS (right). Events include pairs of jets (yellow cones) and missing energy (red or purple lines). Credit: CERN

The Higgs boson lives for an extremely short time before it transforms or “disintegrates” into other particles. It was due to the discovery of some of these decay products that the unique particle was first – and continues to be – observed during a particle collision on the Large Hadron Collider (LHC).


But what if the Higgs boson also disintegrated into unexpected new particles that were invisible to LHC detectors, such as particles that could make up dark matter penetrating the universe? A collaboration between ATLAS and CMS at the LHC has explored this possibility in two recent studies by setting new strict ceilings for the proportion of Higgs bosons that decay into invisible particles.

According to the standard model particle physicsthe Higgs boson indirectly decays into known invisible particles – almost massless particles, so-called. neutrinos– only in 0.1% of cases. However, if dark matter is made up of particles that interact too weakly to be detected, as many physicists suspect, dark matter particles can interact with the Higgs boson and, if not too massive, allow the Higgs boson to decay into it, increasing the proportion of invisible disintegrated Higgs boson.

In their latest independent research, ATLAS and CMS staff looked for invisible Higgs boson decays in proton-proton collision data collected during the LHC’s second launch. Both teams were looking for a specific type of collision in which the Higgs boson is formed as a result of a process known as a vector boson fusion and then breaks up into invisible particles.

These vector boson fusion events contain additional splashes, or “jets,” of particles released to both ends of the particle detectors, making this method of producing the Higgs boson easier to notice than other modes. Together with the “missing energy” in the collision products that invisible particles will suffer, these jets and their properties provide the hallmarks of such invisible Higgs-boson events.

ATLAS and CMS searches found no cases of these invisible Higgs boson events that would exceed the expected number of background events that mimic desired events. However, they showed that the Higgs boson cannot break down into invisible particles more often than a certain percentage of the time: 15% for ATLAS and 18% for CMS, compared to the expected percentage based on computer modeling of the standard model, 10% for both. ATLAS and CMS.

These boundaries coincide well with each other, and when interpreted in the context of dark matter models, they become the limits of the force of interaction of dark matter particles with atomic nuclei, which complement the boundaries obtained by collider-free experiments on dark matter.

As the LHC will be restarted later this year and deliver more data, ATLAS and CMS will no doubt continue to pursue the unseen through the Higgs boson.


Study of dark matter using the Higgs boson


Additional information:
Search for invisible Higgs boson decays obtained by merging vector bosons in proton and proton collisions at s√ = 13 TeV, arXiv: 2201.11585 [hep-ex] arxiv.org/abs/2201.11585

Search for invisible Higgs boson decays in events with vector-boson fusion signatures using 139 fb-1 proton-proton data recorded by the ATLAS experiment, arXiv: 2202.07953 [hep-ex] arxiv.org/abs/2202.07953

Citation: ATLAS and CMS collaboration in pursuit of the unseen with the Higgs boson (2022, February 24), obtained February 24, 2022 from https://phys.org/news/2022-02-atlas-cms-collaborations-invisible- higgs.html

This document is subject to copyright. Except for any honest transaction for the purpose of private study or research, no part may be reproduced without written permission. The content is provided for informational purposes only.



Reported by Source link

RELATED ARTICLES
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Most Popular