Related papers: Direct photons ~basis for characterizing heavy ion…
Direct photon spectra measured at small $p_T$ in p+p, d+Au and Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV are presented. Several measurement techniques including statistical subtraction, tagging, and internal and external conversion were…
Hard photon emitted from energetic heavy ion collisions is of very interesting since it does not experience the late-stage nuclear interaction, therefore it is useful to explore the early-stage information of matter phase. In this work, we…
We discuss the recent status of some penetrating electromagnetic probes of relativistic nuclear collisions, and the information contained in their measurement. We concentrate in turn on sources that produce high p_T photons: those of purely…
This overview focusses on recent developments, in the most part triggered by LHC data, aimed at the development of a reliable and complete theoretical description of high-p$_t$ physics in heavy ion collisions. Particular emphasis is placed…
With the ever-growing number of exoplanets detected, the issue of characterization is becoming more and more relevant. Direct imaging is certainly the most efficient but the most challenging tool to probe the atmosphere of exoplanets and…
A method has been proposed for the determination of $\gamma$ to $\pi^0$ ratio in high energy pp and nucleus-nucleus collisions at large transverse momentum ($p_T$). In photon measuring device, it is proposed that shower shape analysis is…
This work studies the production of direct photons in relativistic nuclear collisions, along with the production of hadrons. Radiation from the very first instants to the final moments of the evolution is included. The hybrid model used…
In this note, we discuss the derivation of a formula that has been used in the literature in order to compute the number of photons emitted by a hot or dense system during a finite time. Our derivation is based on a variation of the…
Photons are a penetrating probe of the hot medium formed in heavy-ion collisions, but they are emitted from all collision stages. At photon energies below 2-3 GeV, the measured photon spectra are approximately exponential and can be…
Heavy-ion collisions at $\sqrt{s_\mathrm{NN}} \sim 10$ GeV probe the QCD phase diagram at large baryon densities. Because the longitudinal Lorentz contraction is small at these collision energies, understanding the dynamics during the early…
The reach of collider energies in heavy-ion collisions has profoundly changed our understanding of QCD under extreme conditions. I review some these new developments and comment on the properties of the produced medium as extracted from…
The dark photon is a new gauge boson whose existence has been conjectured. It is dark because it arises from a symmetry of a hypothetical dark sector comprising particles completely neutral under the Standard Model interactions. Dark though…
Due to the coherence of all the protons in a nucleus, there are very strong electromagnetic fields of short duration in relativistic heavy ion collisions. They give rise to quasireal photon-photon and photon-nucleus collisions with a large…
We consider directly emitted and hadronic decay photons from event-by-event hydrodynamic simulations. We compute the direct photon anisotropic flow coefficients and compare with recent experimental measurements. We find that it is crucial…
The hadronic interactions of the photon are studied in terms of new measurements of the total hadronic cross section and di-jet production in photon-photon collisions at LEP2.
Direct photons associated with jets provide a direct measurement of the effects of energy loss on the fragmentation of the parton as it propagates through the medium. Perturbative QCD calculations describe the direct photon cross section…
In two-photon collisions at LEP2 and a future $e^+e^-$ linear collider heavy quarks (mainly charm) will be pair-produced rather copiously. The production via direct and resolved photons can be distinguished experimentally via a remnant-jet…
We model and constrain the unique indirect detection signature produced by dark matter particles that annihilate through a $U(1)$ gauge symmetry into dark photons that subsequently decay into three-photon final states. We focus on scenarios…
Intensity interferometry of thermal photons, having transverse momenta $k_T \approx $ 0.1 -- 2.0 GeV, produced in relativistic collision of heavy nuclei is studied. It is seen to provide an accurate information about the temporal and…
The search for dark matter and physics beyond the Standard Model has grown to encompass a highly interdisciplinary approach. In this review, we survey recent searches for light, weakly-coupled particles - axions and dark photons - over the…