# Strong interactions

### LHCb measures the effective double parton scattering cross-section with unprecedented precision

In high-energy hadron–hadron collisions, each incoming hadron behaves as a loosely bound system of massless partons – quarks, antiquarks and gluons. The interaction of incoming hadrons is describe...

### ATLAS observes long-range elliptic anisotropies in √s = 13 and 2.76 TeV pp collisions

Measurements of two-particle angular correlations in proton–proton (pp) collisions at the LHC have shown a feature commonly called the “ridge”: an enhancement in production of particle p...

### Penetrating and puzzling: photons shed light on heavy-ion collisions

Résumé Les émissions de photons éclairent les collisions d’ions lourds La lumière émise dans des collisions à haute énergie de noyaux lourds révè...

### CMS observes long-range correlations in pp collisions at 13 TeV

The CMS collaboration has published its first particle-correlation result from proton–proton (pp) collisions at a centre-of-mass energy of 13 TeV. The paper describes the observation of a phenomeno...

### STAR tracker snares heavy flavours

Heavy quarks are important probes of the quark–gluon plasma that is produced when relativistic heavy ions collide. Because of a mass effect, it has been argued that heavy quarks lose less energy thr...

### ALICE in Vienna: from antinuclei to quark–gluon plasma

The 2015 edition of the European Physical Society Conference on High Energy Physics (EPS-HEP 2015), which took place in Vienna in July (“Vienna hosts a high-energy particle waltz”), provid...

### ALICE goes forward with the ridge in pPb collisions

One of the hottest debates at the LHC is the potential emergence of collective effects in proton–lead (pPb) collisions, prompted by the discovery of double ridge structures in angular correlatio...

### The most precise picture of the proton

After 15 years of measurement and another eight years of scrutinizing and calculations, the H1 and ZEUS collaborations have published the most precise results to date about the innermost struct...

### ALICE investigates ‘snowballs in hell’

Résumé L’omelette norvégienne d’ALICE Il n’y a pas uniquement des hadrons ordinaires dans les débris des ” boules de feu ” produites par les collision...

### First full jet measurement in Pb–Pb collisions with ALICE

In high-energy collisions at the LHC, quarks and gluons occasionally scatter violently and produce correlated showers of particles, or “jets”. In proton–proton collisions, the rate o...