Fri·Jul 6, 2018Friday·July 6, 2018

1. 01*

   Correlated long-range mixed-harmonic fluctuations measured in $pp$, $p$+Pb and low-multiplicity Pb+Pb collisions with the ATLAS detector

   ATLAS Collaboration

   Correlations of two flow harmonics $v_n$ and $v_m$ via three- and four-particle cumulants are measured in 13 TeV $pp$, 5.02 TeV $p$+Pb, and 2.76 TeV peripheral Pb+Pb collisions with the ATLAS detector at the LHC. The goal is to understand the multi-particle nature of the long-range collective phenomenon in these collision systems. The large non-flow background from dijet production present in the standard cumulant method is suppressed using a method of subevent cumulants involving two, three and four subevents separated in pseudorapidity. The results show a negative correlation between $v_2$ and $v_3$ and a positive correlation between $v_2$ and $v_4$ for all collision systems and over the full multiplicity range. However, the magnitudes of the correlations are found to depend strongly on the event multiplicity, the choice of transverse momentum range and collision system. The relative correlation strength, obtained by normalisation of the cumulants with the $⟨v_n^2⟩$ from a two-particle correlation analysis, is similar in the three collision systems and depends weakly on the event multiplicity and transverse momentum. These results based on the subevent methods provide strong evidence of a similar long-range multi-particle collectivity in $pp$, $p$+Pb and peripheral Pb+Pb collisions.

   nucl-exhep-exPLB(2019)·76 citations
2. 02*

   Evidence for a 5 MeV Spectral Deviation in the Goesgen Reactor Neutrino Oscillation Experiment

   V. Zacek🇨🇦 · G. Zacek🇨🇦 · P. Vogel🇺🇸 · J.-L. Vuilleumier🇨🇭

   Recent reactor neutrino experiments observe an anomalous excess around 5 MeV in the prompt energy spectra of positrons following the inverse beta decay reaction. In this note we suggest that this 5 MeV anomaly was already present in a much earlier experiment, which was carried out in the 1980's at three distances from the 2.8 GW nuclear powerplant at Goesgen, Switzerland. In particular we demonstrate with a log-likelihood test performed on the Goesgen data that the no-anomaly hypothesis is disfavored at a level of 3.8 sigma.

   ↳ hep-exhep-phnucl-ex13 citations
3. 03*

   Revisiting the isospin relaxation time in intermediate-energy heavy-ion collisions

   Han-Sheng Wang🇨🇳 · Jun Xu🇨🇳 · Bao-An Li🇺🇸 · Wen-Qing Shen🇨🇳

   Isospin relaxation times characterizing isospin transport processes between the projectile and the target with different $N/Z$ ratios and that between the neck and the spectator with different isospin asymmetries and densities in intermediate-energy heavy-ion collisions are studied within an isospin-dependent Boltzmann-Uehling-Uhlenbeck transport model using the lattice Hamiltonian approach. The respective roles and time scales of the isospin diffusion and drift as the major mechanisms of isospin transport in intermediate-energy heavy-ion collisions are discussed. Effects of nuclear symmetry energy and neutron-proton effective mass splitting on the isospin relaxation times are examined.

   ↳ nucl-thnucl-exPRC(2018)·7 citations
4. 04*

   Heavy-ions collisions and fission dynamics with the time-dependent Hartree-Fock theory and its extensions

   C. Simenel🇦🇺 · A.S. Umar🇺🇸

   Microscopic methods and tools to describe nuclear dynamics have considerably been improved in the past few years. They are based on the time-dependent Hartree-Fock (TDHF) theory and its extensions to include pairing correlations and quantum fluctuations. The TDHF theory is the lowest level of approximation of a range of methods to solve the quantum many-body problem, showing its universality to describe many-fermion dynamics at the mean-field level. The range of applications of TDHF to describe realistic systems allowing for detailed comparisons with experiment has considerably increased. For instance, TDHF is now commonly used to investigate fusion, multi-nucleon transfer and quasi-fission reactions. Thanks to the inclusion of pairing correlations, it has also recently led to breakthroughs in our description of the saddle to scission evolution, and, in particular, the non-adiabatic effects near scission. Beyond mean-field approaches such as the time-dependent random-phase approximation (TDRPA) and stochastic mean-field methods have reached the point where they can be used for realistic applications. We review recent progresses in both techniques and applications to heavy-ion collision and fission.

   ↳ nucl-thnucl-exPPNP(2018)·180 citations
5. 05*

   Optimized MPGD-based Photon Detectors for high momentum particle identification at the Electron-Ion Collider

   J. Agarwala · F. Bradamante · A. Bressan · C. Chatterjee · P. Ciliberti · S. Dalla Torre · S. Dasgupta · M. Gregori · S. Levorato · A. Martin · G. Menon · F. Tessarotto · Y. Zhao

   Particle IDentification (PID) is a central requirement of the experiments at the future EIC. Hadron PID at high momenta by RICH techniques requires the use of low density gaseous radiators, where the challenge is the limited length of the radiator region available at a collider experiment. By selecting a photon wavelength range in the far UV domain, around 120 nm, the number of detectable photons can be increased. Ideal sensors are gaseous Photon Detectors (PD) with CsI photocathode, where the status of the art is represented by the MPGD-based PDs at COMPASS RICH. Detector optimization is required for the application at EIC. Here we report about a dedicated prototype where the sensor pad-size has been reduced to preserve the angular resolution. A new DAQ system based on the SRS readout electronics has been developed for the laboratory and test beam studies of the prototype.

   ↳ physics.ins-dethep-exnucl-exNucl.Instrum.Meth.A(2019)·2 citations
6. 06*

   The CBM Time-of-Flight system

   I. Deppner🇩🇪 · N. Herrmann🇩🇪

   The Compressed Baryonic Matter spectrometer (CBM) is a future fixed-target heavy-ion experiment located at the Facility for Anti-proton and Ion Research (FAIR) in Darmstadt, Germany. The key element in CBM providing hadron identification at incident beam energies between 2 and 11 AGeV (for Au-nuclei) will be a 120 m${}^2$ large Time-of-Flight (ToF) wall composed of Multi-gap Resistive Plate Chambers (MRPC) with a system time resolution better than 80 ps. Aiming for an interaction rate of 10 MHz for Au+Au collisions the MRPCs have to cope with an incident particle flux between 0.1~kHz/cm${}^2$ and 100~kHz/cm${}^2$ depending on their location. Characterized by granularity and rate capability the actual conceptual design of the ToF-wall foresees 6 different counter granularities and 4 different counter designs. In order to elaborate the final MRPC design of these counters several heavy-ion in-beam and cosmic tests were performed. In this contribution we present the conceptual design of the TOF wall and in particular discuss performance results of full-size MRPC prototypes.

   ↳ physics.ins-detnucl-exJINST(2019)·26 citations
7. 07*

   Effect of flavor-dependent partonic transverse momentum on the determination of the $W$ boson mass in hadronic collisions

   Alessandro Bacchetta🇮🇹 · Giuseppe Bozzi🇮🇹 · Marco Radici🇮🇹 · Mathias Ritzmann🇺🇸 · Andrea Signori🇺🇸

   Within the framework of transverse-momentum-dependent factorization, we investigate for the first time the impact of a flavor-dependent intrinsic transverse momentum of quarks on the production of $W^{\pm }$ bosons in proton-proton collisions at $\sqrt{s}$ = 7 TeV. We estimate the shift in the extracted value of the $W$ boson mass $M_W$ induced by different choices of flavor-dependent parameters for the intrinsic quark transverse momentum by means of a template fit to the transverse-mass and the lepton transverse-momentum distributions of the $W$-decay products. We obtain $-6\le \Delta M_{W^{+}}\le 9$ MeV and $-4\le \Delta M_{W^{-}}\le 3$ MeV with a statistical uncertainty of $\pm 2.5$ MeV. Our findings call for more detailed investigations of flavor-dependent nonperturbative effects linked to the proton structure at hadron colliders.

   ↳ hep-phhep-exnucl-exnucl-thPLB(2019)·54 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.