Thu·Jan 31, 2019Thursday·January 31, 2019

1. 01*

   Studies of the Three-Body Breakup in Deuteron-Deuteron Collisions near the Quasi-Free Limit at 160 MeV

   I. Ciepał🇵🇱 · G. Khatri🇵🇱 · K. Bodek🇵🇱 · A. Deltuva🇱🇹 · A. C. Fonseca · N. Kalantar-Nayestanaki🇳🇱 · St. Kistryn🇵🇱 · B. Kłos🇵🇱 · A. Kozela🇵🇱 · J. Kuboś🇵🇱 · P. Kulessa🇵🇱 · A. Łobejko🇵🇱 and 11 other authors

   A set of differential cross section of the three-body ${}^2$H($d$,$dp$)$n$ breakup reaction at 160 MeV deuteron beam energy are presented for 147 kinematically complete configurations near the quasi-free scattering kinematics. The experiment was performed at KVI in Groningen, the Netherlands using the BINA detector. The cross-section data have been normalized to the ${}^2$H($d$,$d$)${}^2$H elastic scattering cross section. The data are compared to the recent single-scattering approximation (SSA) calculations for three-cluster breakup in deuteron-deuteron collisions. Confronting the SSA predictions with the experimental data shows that SSA provides the correct order of magnitude of the cross-section data. The studied energy is probably too low to meet the SSA assumptions which prevents better accuracy of the description.

   nucl-exnucl-thPRC(2019)·13 citations
2. 02*

   Shining a Light on the QGP - Electroweak Probes Experimental Summary

   Friederike Bock (CERN)🇨🇭

   Objects which are only subject to the electroweak force are an ideal probe of QCD in high density and temperature environments as they carry information about the conditions during their production out of the QGP without interacting with it. Thus they can be used to characterize the initial state as well as several properties of the QGP and its evolution. Within this article the recent results regarding these electroweak probes presented at the 9${}^{th}$ Hard Probes Conference (Aix-les-Bains, France, 2018) will be summarized. In particular the following questions will be addressed: Can we determine the necessary energy and particle density for the QGP creation using electromagnetic probes? Can we use light-by-light scattering in heavy-ion collisions to do precision tests of QED and measure the magnetic field of the QGP? How are quark jets modified by the presence of the QGP? What can we learn about the initial state and scaling properties in pp, p(d)-A and A-A collisions from the production of high \pt\ photons, Z${}^0$ and W${}^{\pm }$ bosons? In the version provided on arXiv, additional plots are included in the appendix with respect to the version submitted for publication in the journal.

   nucl-exhep-exPoS(2019)·2 citations
3. 03*

   The influence of Fermi motion on the comparison of the polarization transfer to a proton in elastic $\vec{e}p$ and quasi-elastic $\vec{e}A$ scattering

   S. Paul🇩🇪 · T. Brecelj🇸🇮 · H. Arenhövel🇩🇪 · P. Achenbach🇩🇪 · A. Ashkenazi🇺🇸 · J. Beričič🇺🇸 · R. Böhm🇩🇪 · D. Bosnar🇭🇷 · E.O. Cohen🇮🇱 · L. Debenjak🇸🇮 · M.O. Distler🇩🇪 · A. Esser🇩🇪 and 26 other authors

   A comparison between polarization-transfer to a bound proton in quasi-free kinematics by the A$(\vec{e},e^{\prime }\vec{p})$ knockout reaction and that in elastic scattering off a free proton can provide information on the characteristics of the bound proton. In the past the reported measurements have been compared to those of a free proton with zero initial momentum. We introduce, for the first time, expressions for the polarization-transfer components when the proton is initially in motion and compare them to the ${}^2$H data measured at the Mainz Microtron (MAMI). We show the ratios of the transverse ($P_x$) and longitudinal ($P_z$) components of the polarization transfer in ${}^2\text{H}(\vec{e},e^{\prime }\vec{p})\text{n}$, to those of elastic scattering off a "moving proton", assuming the proton's initial (Fermi) momentum equals the negative missing momentum in the measured reaction. We found that the correction due to the proton motion is up to 20\% at high missing momentum. However the effect on the double ratio $\frac{(P_x/P_z{)}^A}{(P_x/P_z{)}^{{}^1\text{H}}}$ is largely canceled out, as shown for both ${}^2$H and ${}^{12}$C data. This implies that the kinematics is not the primary cause for the deviations between quasi-elastic and elastic scattering reported previously.

   nucl-exPLB(2019)·7 citations
4. 04*

   Initial state description of azimuthally collimated long range correlations in ultrarelativistic light-heavy ion collisions

   Mark Mace🇫🇮 · Vladimir V. Skokov🇺🇸 · Prithwish Tribedy🇺🇸 · Raju Venugopalan🇺🇸

   It was argued in arXiv:1805.09342 and arXiv:1807.00825 that the systematics of the azimuthal anisotropy coefficients $v_{2,3}$ measured in ultrarelativistic light-heavy ion collisions at RHIC and the LHC can be described in an initial state dilute-dense Color Glass Condensate (CGC) framework. We elaborate here on the discussion in these papers and provide further novel results that strengthen their conclusions. The underlying mathematical framework and numerical techniques employed are very similar to those in the CGC based IP-Glasma model used previously as initial conditions for heavy-ion collisions. The uncertainties in theory/data comparisons for small systems are discussed, with unknowns that are specific to the model distinguished from those that are generic to all models. We present analytical arguments that demonstrate that quantum interference effects such as Bose enhancement and Hanbury-Brown-Twiss correlations of gluons, as well as coherent multiple scattering of gluons in the projectile off color domains in the target, are enhanced in rare events. The quantum origins of the large anisotropies in small systems are corroborated by numerical results for deuteron-gold collisions that show that large anisotropies in rare configurations can occur when the nucleons in the projectile overlap significantly. This is at variance with the classical intuition of hydrodynamical models. We also comment on the consequences of ignoring the many-body color charge correlations of gluons in models that only consider geometrical fluctuations in the energy density.

   ↳ hep-phnucl-exnucl-th6 citations
5. 05*

   Evolution of multiplicity fluctuations in heavy ion collisions

   Radka Sochorova🇨🇿 · Boris Tomasik🇸🇰

   The evolution of multiplicity distribution of a species which undergoes chemical reactions can be described with the help of a master equation. We study the master equation for a fixed temperature, because we want to know how fast different moments of the multiplicity distribution approach their equilibrium value. We particularly look at the 3rd and 4th factorial moments and their equilibrium values from which central moments, cumulants and their ratios can be calculated. Then we study the situation in which the temperature of the system decreases. We find out that in the non-equilibrium state, higher factorial moments differ more from their equilibrium values than the lower moments and that the behaviour of the combination of the central moments depends on the combination we choose. If one chooses to determine the chemical freeze-out temperature from the measured values of higher moments, these effects might jeopardise the correctness of the extracted value.

   ↳ nucl-thhep-phnucl-exPoS(2019)·0 citations
6. 06*

   Future heavy-ion facilities: FCC-AA

   A. Dainese🇮🇹 · L. Apolinario🇵🇹 · N. Armesto🇪🇸 · D. d'Enterria🇨🇭 · J.M. Jowett🇨🇭 · J.-P. Lansberg🇫🇷 · J.G. Milhano🇵🇹 · C.A. Salgado🇪🇸 · M. Schaumann🇨🇭 · M. van Leuween🇳🇱 · U.A. Wiedemann🇨🇭

   The operation of the Future Circular Collider (FCC) with heavy ions would provide Pb-Pb and p-Pb collisions at sqrt{s_NN}= 39 and 63 TeV, respectively, per nucleon-nucleon collision, with projected per-month integrated luminosities of up to 110/nb and 29/pb, respectively. This document outlines the unique and broad physics opportunities with heavy ions at the energy frontier opened by FCC.

   ↳ hep-phnucl-exnucl-thPoS(2019)·3 citations
7. 07*

   Cryogenic light detectors with enhanced performance for rare events physics

   M. Barucci🇮🇹 · J.W. Beeman🇺🇸 · V. Caracciolo🇮🇹 · L. Pagnanini🇮🇹 · L. Pattavina🇮🇹 · G. Pessina🇮🇹 · S. Pirro🇮🇹 · C. Rusconi🇮🇹 · K. Schäffner🇮🇹

   We have developed and tested a new way of coupling bolometric light detectors to scintillating crystal bolometers based upon simply resting the light detector on the crystal surface, held in position only by gravity. This straightforward mounting results in three important improvements: (1) it decreases the amount of non-active materials needed to assemble the detector, (2) it substantially increases the light collection efficiency by minimizing the light losses induced by the mounting structure, and (3) it enhances the thermal signal induced in the light detector thanks to the extremely weak thermal link to the thermal bath. We tested this new technique with a 16 cm${}^2$ Ge light detector with thermistor readout sitting on the surface of a large TeO${}_2$ bolometer. The light collection efficiency was increased by greater than 50\% compared to previously tested alternative mountings. We obtained a baseline energy resolution on the light detector of 20~eV RMS that, together with increased light collection, enabled us to obtain the best $\alpha$ vs $\beta /\gamma$ discrimination ever obtained with massive TeO${}_2$ crystals. At the same time we achieved rise and decay times of 0.8 and 1.6 ms, respectively. This superb performance meets all of the requirements for the CUPID (CUORE Upgrade with Particle IDentification) experiment, which is a 1-ton scintillating bolometer follow up to CUORE.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2019)·21 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.