Today, exactly ten years after announcing the discovery of the Higgs boson,
the international ATLAS and CMS collaborations at the Large Hadron Collider
(LHC) report the results of their most comprehensive studies yet of the
properties of this unique particle. The independent studies, described in
two papers published today in Nature, show that the particle's properties
are remarkably consistent with those of the Higgs boson predicted by the
Standard Model of particle physics. The studies also show that the particle
is increasingly becoming a powerful means to search for new, unknown
phenomena that—if found—could help shed light on some of the biggest
mysteries of physics, such as the nature of the mysterious dark matter
present in the universe.
The Higgs boson is the particle manifestation of an all-pervading quantum
field, known as the Higgs field, that is fundamental to describe the
universe as we know it. Without this field, elementary particles such as the
quark constituents of the protons and neutrons of atomic nuclei, as well as
the electrons that surround the nuclei, would not have mass, and nor would
the heavy particles (W bosons) that carry the charged weak force, which
initiates the nuclear reaction that powers the Sun.
To explore the full potential of the LHC data for the study of the Higgs
boson, including its interactions with other particles, ATLAS and CMS
combine numerous complementary processes in which the Higgs boson is
produced and "decays" into other particles.
This is what the collaborations have done in their new, independent studies,
using their full LHC Run 2 data sets, which each include over 10 000
trillion proton–proton collisions and about 8 million Higgs bosons—30 times
more than at the time of the particle's discovery. The new studies each
combine an unprecedented number and variety of Higgs boson production and
decay processes to obtain the most precise and detailed set of measurements
to date of their rates, as well as of the strengths of the Higgs boson's
interactions with other particles.
All of the measurements are remarkably consistent with the Standard Model
predictions within a range of uncertainties depending, among other criteria,
on the abundance of a given process. For the Higgs boson's interaction
strength with the carriers of the weak force, an uncertainty of 6% is
achieved. By way of comparison, similar analyses with the full Run 1 data
sets resulted in a 15% uncertainty for that interaction strength.
"After just ten years of Higgs boson exploration at the LHC, the ATLAS and
CMS experiments have provided a detailed map of its interactions with force
carriers and matter particles," says ATLAS spokesperson Andreas Hoecker.
"The Higgs sector is directly connected with very profound questions related
to the evolution of the early universe and its stability, as well as to the
striking mass pattern of matter particles. The Higgs boson discovery has
sparked an exciting, deep and broad experimental effort that will extend
throughout the full LHC program."
"Sketching such a portrait of the Higgs boson this early on was unthinkable
before the LHC started operating," says CMS spokesperson Luca Malgeri. "The
reasons for this achievement are manifold and include the exceptional
performances of the LHC and of the ATLAS and CMS detectors, and the
ingenious data analysis techniques employed."
The new combination analyses also provide, among other new results,
stringent bounds on the Higgs boson's interaction with itself and also on
new, unknown phenomena beyond the Standard Model, such as on Higgs boson
decays into invisible particles that may make up dark matter.
ATLAS and CMS will continue revealing the nature of the Higgs boson using
data from the LHC's Run 3, which starts tomorrow at a new high-energy
frontier, and from the collider's major upgrade, the High-Luminosity LHC
(HL-LHC), from 2029. With about 18 million Higgs bosons projected to be
produced in each experiment in Run 3 and some 180 million in the HL-LHC's
runs, the collaborations expect to not only reduce significantly the
measurement uncertainties of the Higgs boson's interactions determined so
far but also to observe some of the Higgs boson's interactions with the
lighter matter particles and to obtain the first significant evidence of the
boson's interaction with itself.
Reference:
The CMS Collaboration. A portrait of the Higgs boson by the CMS experiment
ten years after the discovery. Nature (2022).
DOI: 10.1038/s41586-022-04892-x
,
The ATLAS Collaboration, A detailed map of Higgs boson interactions by the
ATLAS experiment ten years after the discovery, Nature (2022).
DOI: 10.1038/s41586-022-04893-w.
Tags:
Physics