Thu·Jan 30, 2020Thursday·January 30, 2020

1. 01*

   Using precision timing to improve particle tracking

   Spencer R. Klein🇺🇸

   Silicon tracking detectors provide excellent spatial resolution, and so can provide excellent momentum resolution for energetic charged particles, even in compact detectors. However, at lower momenta, multiple scattering in the silicon degrades the momentum resolution. We present an alternate method to measure momentum and alleviate this degradation, using silicon detectors that also incorporate timing measurements. By using timing information between two silicon layers, it is possible to solve for the the radius of curvature, and hence the particle momentum, independent of multiple scattering within the silicon. We consider three examples: an all-silicon central tracker for an electron-ion collider, a simplified version of the CMS detector, and a forward detector for an electron-ion collider. For a 75 cm diameter tracker in a 1.5 T magnetic field, timing can improve the momentum determination for particles with momentum below 500 MeV/c. In the 3.8 T CMS magnetic field and 1.2 m radius tracker, timing can improve tracking up to momenta of 1.3 GeV/c. The resolution is best at mid-rapidity. We also discuss a simpler system, consisting of a single timing detector outside an all-silicon tracker.

   ↳ physics.ins-detnucl-exJINST(2020)·3 citations
2. 02*

   Number of constituent quark scaling of elliptic flows in high multiplicity p-Pb collisions at $\sqrt{s_{NN}}=$ 5.02 TeV

   Wenbin Zhao🇨🇳 · Che Ming Ko🇺🇸 · Yu-Xin Liu🇨🇳 · Guang-You Qin🇨🇳 · Huichao Song🇨🇳

   We briefly summarize our recent study on the number of constituent quark (NCQ) scaling of hadron elliptic flows in high multiplicity p-Pb collisions at $\sqrt{s_{NN}}=$ 5.02 TeV. With the inclusion of hadron production via the quark coalescence model at intermediate $p_T$, the viscous hydrodynamics at low $p_T$, and jet fragmentation at high $p_T$, our $Hydro-Coal-Frag$ model provides a nice description of the $p_T$-spectra and differential elliptic flow $v_2(p_T)$ of pions, kaons and protons over the $p_T$ range from 0 to 6 GeV. Our results demonstrate that including the quark coalescence is essential for reproducing the observed approximate NCQ scaling of hadron $v_2$ at intermediate $p_T$ in experiments, indicating strongly the existence of partonic degrees of freedom and the formation of quark-gluon plasma in high multiplicity p--Pb collisions at the LHC.

   ↳ nucl-thhep-phnucl-exNPA(2021)·2 citations
3. 03*

   Review of proton and nuclear shape fluctuations at high energy

   Heikki Mäntysaari🇫🇮

   Determining the inner structure of protons and nuclei in terms of their fundamental constituents has been one of the main tasks of high energy nuclear and particle physics experiments. This quest started as a mapping of the (average) parton densities as a function of longitudinal momentum fraction and resolution scale. Recently, the field has progressed to more differential imaging, where one important development is the description of the event-by-event quantum fluctuations in the wave function of the colliding hadron. In this Review, recent developments on the extraction of proton and nuclear transverse geometry with event-by-event fluctuations from collider experiments at high energy is presented. The importance of this fundamentally interesting physics in other collider experiments like in studies of the properties of the Quark Gluon Plasma is also illustrated.

   ↳ hep-phhep-exnucl-exnucl-thRept.Prog.Phys.(2020)·103 citations
4. 04*

   Confronting Experimental Data with Heavy-Ion Models: Rivet for Heavy Ions

   Christian Bierlich🇸🇪 · Andy Buckley🇬🇧 · Christian Holm Christensen🇩🇰 · Peter Harald Lindenov Christiansen🇸🇪 · Cody B. Duncan🇦🇺 · Jan Fiete Grosse-Oetringhaus🇨🇭 · Przemyslaw Karczmarczyk🇵🇱 · Patrick Kirchgaeßer🇩🇪 · Jochen Klein🇮🇹 · Leif Lönnblad🇸🇪 · Roberto Preghenella🇮🇹 · Christine O. Rasmussen🇸🇪 · Maria Stefaniak🇵🇱 · Vytautas Vislavicus🇩🇰

   The Rivet library is an important toolkit in particle physics, and serves as a repository for analysis data and code. It allows for comparisons between data and theoretical calculations of the final state of collision events. This paper outlines several recent additions and improvements to the framework to include support for analysis of heavy ion collision simulated data. The paper also presents examples of these recent developments and their applicability in implementing concrete physics analyses.

   ↳ hep-phhep-exnucl-exnucl-thEPJC(2020)·25 citations
5. 05*

   Production of ${}^4\mathrm{Li}$ and $p-{}^3\mathrm{He}$ correlation function in relativistic heavy-ion collisions

   Sylwia Bazak🇵🇱 · Stanislaw Mrowczynski🇵🇱

   The thermal and coalescence models both describe well yields of light nuclei produced in relativistic heavy-ion collisions at LHC. We propose to measure the yield of ${}^4\mathrm{Li}$ and compare it to that of ${}^4\mathrm{He}$ to falsify one of the models. Since the masses of ${}^4\mathrm{He}$ and ${}^4\mathrm{Li}$ are almost equal, the yield of ${}^4\mathrm{Li}$ is about 5 times bigger than that of ${}^4\mathrm{He}$ in the thermal model because of different numbers of spin states of the two nuclides. Their internal structures are, however, very different: the alpha particle is well bound and compact while ${}^4\mathrm{Li}$ is weakly bound and loose. Consequently, the ratio of yields of ${}^4\mathrm{Li}$ to ${}^4\mathrm{He}$ is significantly smaller in the coalescence model and it strongly depends on the collision centrality. Since the nuclide ${}^4\mathrm{Li}$ is unstable and it decays into ${}^3\mathrm{He}$ and $p$, the yield of ${}^4\mathrm{Li}$ can be experimentally obtained through a measurement of the $p-{}^3\mathrm{He}$ correlation function. The function carries information not only about the yield of ${}^4\mathrm{Li}$ but also about the source of ${}^3\mathrm{He}$ and allows one to determine through a source-size measurement whether of ${}^3\mathrm{He}$ is directly emitted from the fireball or it is formed afterwards. We compute the correlation function taking into account the $s-$wave scattering and Coulomb repulsion together with the resonance interaction responsible for the ${}^4\mathrm{Li}$ nuclide. We discuss how to infer information about an origin of ${}^3\mathrm{He}$ from the correlation function, and finally a method to obtain the yield of ${}^4\mathrm{Li}$ is proposed.

   ↳ nucl-thhep-phnucl-exEPJA(2020)·28 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.