# Strong interactions

### Lead nuclei under scrutiny at LHCb

In 2016 the LHC collided protons and lead nuclei for the first time at a centre-of-mass energy of 8.16 TeV per nucleon–nucleon pair. In lead–lead collisions, the formation of the quark–gluon p...

Read article 'Precision study reveals proton to be lighter'

### Precision study reveals proton to be lighter

A team in Germany has made the most precise measurement to date of the mass of a single proton, achieving a precision of 32 parts-per-trillion (ppt). The result not only improves on the precision of ...

Read article 'KEDR pins down R at low energies'

### KEDR pins down R at low energies

The KEDR collaboration has used the VEPP-4M electron–positron collider at the Budker Institute in Russia to make the most precise measurement of the quantity “R” in the low-energy range. R is de...

Read article 'FAIR forges its future'

### FAIR forges its future

Supernova explosions, neutron-star mergers and rare radioactive ions might not seem to have much connection to terrestrial matters. Yet, while the lightest elements were synthesised immediately after ...

Read article 'Proton–proton collisions become stranger'

### Proton–proton collisions become stranger

Recreating the intense fireball of quarks and gluons that existed immediately after the Big Bang, the quark–gluon plasma (QGP), traditionally requires high-energy collisions between heavy ions such ...

Read article 'LHCb brings cosmic collisions down to Earth'

### LHCb brings cosmic collisions down to Earth

In an effort to improve our understanding of cosmic rays, the LHCb collaboration has generated high-energy collisions between protons and helium nuclei similar to those that take place when cosmic ray...

Read article 'ALICE reveals dominance of collective flow'

### ALICE reveals dominance of collective flow

The study of the anisotropic flow in heavy-ion collisions at the LHC, which measures the momentum anisotropy of the final-state particles, has been effective in characterising the extreme states of ma...

Read article 'ATLAS reveals more strangeness in the proton'

### ATLAS reveals more strangeness in the proton

The excellent theoretical understanding of the production of electroweak W and Z gauge bosons in proton–proton collisions at the LHC makes these “standard-candle” processes ideal for studying th...