Energy-energy correlators are a powerful tool in probing the dynamics of high-energy particle collisions. They have been particularly useful in heavy ion collisions where the quark-gluon plasma is formed. In a recent study conducted by the CMS Collaboration at CERN, energy-energy correlators were measured inside high transverse momentum jets in lead-lead collisions for the first time. The data was obtained at a center-of-mass energy of 5.02 TeV with an integrated luminosity of 1.70 nb$^{-1}$. The results revealed significant modifications to jet substructure in the presence of the quark-gluon plasma. To isolate the effects of the jet wake, a double ratio of PbPb to pp ratios was taken across different transverse momentum ranges and centrality classes. This analysis provided insights into how the quark-gluon plasma influences jet substructure at various collision conditions. The results showed that there are substantial modifications to energy-energy correlators in heavy ion collisions compared to proton-proton collisions at the same energy. Furthermore, comparisons were made with theoretical models incorporating color coherence or medium response effects. Interestingly, both types of models predicted similar modifications to jet substructure in heavy ion collisions, highlighting the complex interplay between perturbative and nonperturbative quantum chromodynamics phenomena in these extreme collision environments. Overall, this study sheds light on the intricate dynamics of high-energy nuclear interactions and provides valuable information for understanding the properties of the quark-gluon plasma through detailed measurements of energy-energy correlators inside jets. The results contribute to our knowledge of strong interaction physics and offer new avenues for exploring fundamental aspects of particle physics under extreme conditions.
SummaryEnergy-energy correlators help us learn about what happens when particles collide at high speeds. They are especially helpful in studying heavy ion collisions, where a special kind of hot soup is created. Scientists at CERN recently measured energy-energy correlators inside fast-moving jets during these collisions for the first time. They found that the jet's structure changes a lot when it travels through the hot soup. By comparing different types of collisions and using special calculations, scientists can figure out how this hot soup affects the jets in different situations.
Definitions
- Energy-energy correlators: Tools used to study how energy is distributed between particles after they collide.
- High-energy particle collisions: When tiny particles crash into each other with a lot of speed and force.
- Quark-gluon plasma: A super-hot state of matter where quarks and gluons move freely.
- Transverse momentum: The motion of particles perpendicular to their direction of travel.
- Jet substructure: The internal arrangement or organization of particles within a jet produced by high-speed collisions.
Energy-energy correlators have emerged as a powerful tool in probing the dynamics of high-energy particle collisions. These correlations, which measure the energy flow between particles, provide valuable insights into the underlying physics of these interactions. In particular, they have been instrumental in studying heavy ion collisions where a unique state of matter known as quark-gluon plasma (QGP) is formed.
In a recent study conducted by the CMS Collaboration at CERN, energy-energy correlators were measured inside high transverse momentum jets in lead-lead (PbPb) collisions for the first time. The data was obtained at a center-of-mass energy of 5.02 TeV with an integrated luminosity of 1.70 nb$^{-1}$. This allowed researchers to investigate how QGP affects jet substructure under different collision conditions.
The results revealed significant modifications to jet substructure in the presence of QGP. To isolate the effects of the jet wake, a double ratio of PbPb to proton-proton (pp) ratios was taken across different transverse momentum ranges and centrality classes. This analysis provided insights into how QGP influences jet substructure at various collision conditions.
The findings showed that there are substantial modifications to energy-energy correlators in heavy ion collisions compared to proton-proton collisions at the same energy. This suggests that QGP plays a crucial role in shaping jet substructure and provides evidence for its existence.
To further understand these modifications, comparisons were made with theoretical models incorporating color coherence or medium response effects. Interestingly, both types of models predicted similar changes to jet substructure in heavy ion collisions, highlighting the complex interplay between perturbative and nonperturbative quantum chromodynamics phenomena in these extreme environments.
Overall, this study sheds light on the intricate dynamics involved in high-energy nuclear interactions and provides valuable information for understanding the properties of QGP through detailed measurements of energy-energy correlators inside jets. The results contribute to our knowledge of strong interaction physics and offer new avenues for exploring fundamental aspects of particle physics under extreme conditions.
The measurement of energy-energy correlators inside high transverse momentum jets in PbPb collisions opens up a new window into the study of QGP. It allows researchers to probe the properties and behavior of this unique state of matter in more detail, providing insights into its formation and evolution.
Moreover, these measurements have important implications for understanding the nature of QGP. By studying how it affects jet substructure, researchers can gain a better understanding of its properties such as viscosity, temperature, and density. This information is crucial for developing a comprehensive understanding of QGP and its role in the early universe.
In addition to its significance in heavy ion collisions, energy-energy correlators also have applications in other areas such as proton-proton collisions at higher energies or even astrophysical phenomena like black hole mergers. Therefore, this study not only contributes to our understanding of nuclear interactions but also has broader implications for various fields within physics.
In conclusion, the CMS Collaboration's recent measurement of energy-energy correlators inside high transverse momentum jets in PbPb collisions provides valuable insights into the dynamics of high-energy nuclear interactions and sheds light on the properties of QGP. These findings open up new avenues for further research and pave the way for a deeper understanding of fundamental aspects of particle physics under extreme conditions.
Energy-energy correlators are constructed by averaging the number of charged particle pairs within jets, weighted by the product of their transverse momenta, as a function of the angular separation of the particles within a pair. They are sensitive to a multitude of perturbative and nonperturbative quantum chromodynamics phenomena in high-energy particle collisions. Using lead-lead data recorded with the CMS detector, energy-energy correlators inside high transverse momentum jets are measured in heavy ion collisions for the first time. The data are obtained at a nucleon-nucleon center-of-mass energy of 5.02 TeV and correspond to an integrated luminosity of 1.70 nb$^{-1}$. A similar analysis is done for proton-proton collisions at the same center-of-mass energy to establish a reference. The ratio of lead-lead to proton-proton energy-energy correlators reveals significant jet substructure modifications in the quark-gluon plasma. The results are compared to different models that incorporate either color coherence or medium response effects, where the two effects predict similar substructure modifications.
