Tue·Nov 19, 2019Tuesday·November 19, 2019

1. 01*

   Excitation functions of related parameters from transverse momentum (mass) spectra in high energy collisions

   Li-Li Li🇨🇳 · Fu-Hu Liu🇨🇳 · Muhammad Waqas🇨🇳 · Rasha Al-Yusufi🇨🇳 · Altaf Mujear🇨🇳

   Transverse momentum (mass) spectra of positively and negatively charged pions, positively and negatively charged kaons, protons and antiprotons produced at mid-(pseudo)rapidity in various collisions at high energies are analyzed in this work. The experimental data measured in central gold-gold, central lead-lead, and inelastic proton-proton collisions by several international collaborations are studied. The (two-component) standard distribution is used to fit the data and extract the excitation function of effective temperature. Then, the excitation functions of kinetic freeze-out temperature, transverse flow velocity, and initial temperature are obtained. In the considered collisions, the four parameters increase with the increase of collision energy in general, and the kinetic freeze-out temperature appears the trend of saturation at the top Relativistic Heavy Ion Collider and the Large Hadron Collider.

   ↳ hep-phhep-exnucl-exnucl-thAdv.High Energy Phys.(2020)·15 citations
2. 02*

   Search for dark matter induced de-excitation of ${}^{180}$Ta${}^{\mathrm{m}}$

   Björn Lehnert🇺🇸 · Harikrishnan Ramani🇺🇸 · Mikael Hult🇧🇪 · Guillaume Lutter🇧🇪 · Maxim Pospelov🇨🇦 · Surjeet Rajendran🇺🇸 · Kai Zuber🇩🇪

   Weak-scale dark matter particles, in collisions with nuclei, can mediate transitions between different nuclear energy levels. In particular, owing to sizeable momentum exchange, dark matter particles can enable de-excitation of nuclear isomers that are extremely long lived with respect to regular radioactive decays. In this paper, we utilize data from a past experiment with ${}^{180}$Ta${}^{\mathrm{m}}$ to search for $\gamma$-lines that would accompany dark matter induced de-excitation of this isomer. Non-observation of such transitions above background yields the first direct constraint on the lifetime of ${}^{180}$Ta${}^{\mathrm{m}}$ against DM-initiated transitions: $T_{1/2}>1.3\times 10^{14}$~a at 90\% C.I. Using this result, we derive novel constraints on dark matter models with strongly interacting relics, and on models with inelastic dark matter particles. Existing constraints are strengthened by this independent new method. The obtained limits are also valid for the Standard Model $\gamma$-decay of ${}^{180}$Ta${}^{\mathrm{m}}$.

   ↳ astro-ph.COhep-exhep-phnucl-ex+1PRL(2020)·41 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.