Thu·Jul 2, 2020Thursday·July 2, 2020

1. 01*

   Study of freeze-out dynamics of strange hadrons

   Sushant K. Singh🇮🇳 · Purabi Ghosh🇮🇳 · Jajati K. Nayak🇮🇳

   We study the chemical freeze-out dynamics of strange particles ($K,\Lambda ,\Sigma$) from a homogeneous and isotropically expanding hadronic system of $\pi ,K,\rho ,N,\Lambda$ and $\Sigma$ with zero net baryon density. We use the momentum integrated Boltzmann equation and study their evolution over the bulk hadronic matter, a condition being similar to the one created at top RHIC and LHC energies. The cross-sections, which are input to the equations, are taken either from phenomenological models or parameterized by comparing against experimental data. From this microscopic calculation we find that these strange particles freeze-out near transition temperature $\approx T_c$ due to large relaxation time. The continuous cease of the inelastic processes due to gradual fall in the temperature and decrease in the number density, thus lead to early freeze out of strange hadrons $K,\Lambda$ and $\Sigma$ which happens sequentially near $T_c$. However, freeze-out of these strange species near Tc appears as a sudden and simultaneous process, which is mostly predicted by thermal model while explaining the yield of identified particles at RHIC and LHC energies.

   ↳ nucl-thhep-exhep-phnucl-exPRD(2021)·8 citations
2. 02*

   Active-sterile neutrino mixing constraint using reactor antineutrinos with the ISMRAN set-up

   S. P. Behera🇮🇳 · D. K. Mishra🇮🇳 · L. M. Pant🇮🇳

   In this work, we present an analysis of the sensitivity to the active-sterile neutrino mixing with the Indian Scintillator Matrix for Reactor Anti-Neutrino (ISMRAN) experimental set-up at very short baseline. In this article, we have considered the measurement of electron antineutrino induced events employing a single detector which can be placed either at a single position or moved between near and far positions from the given reactor core. Results extracted in the later case are independent of the theoretical prediction of the reactor anti-neutrino spectrum and detector related systematic uncertainties. Our analysis shows that the results obtained from the measurement carried out at a combination of the near and far detector positions are improved significantly at higher $\Delta m_{41}^2$ compared to the ones obtained with the measurement at a single detector position only. It is found that the best possible combination of near and far detector positions from a 100 MW${}_{th}$ power DHRUVA research reactor core are 7 m and 9 m, respectively, for which ISMRAN set-up can exclude in the range 1.4 $e{V}^2\le \Delta m_{41}^2\le$ 4.0 $e{V}^2$ of reactor antineutrino anomaly region along with the present best-fit point of active-sterile neutrino oscillation parameters. At those combinations of detector positions, the ISMRAN set-up can observe the active sterile neutrino oscillation with a 95$\%$ confidence level provided that ${\sin }^{2}2{\theta }_{14}\ge 0.09$ at $\Delta m_{41}^2$ = 1 eV${}^2$ for an exposure of 1 ton-yr. The active-sterile neutrino mixing sensitivity can be improved by about 22\% at the same exposure by placing the detector at near and far distances of 15 m and 17 m, respectively, from the compact proto-type fast breeder reactor (PFBR) facility which has a higher thermal power of 1250 MW${}_{th}$.

   ↳ hep-phnucl-exnucl-thphysics.ins-detPRD(2020)·15 citations
3. 03*

   Investigating the XENON1T Low-Energy Electronic Recoil Excess Using NEST

   M. Szydagis🇺🇸 · C. Levy🇺🇸 · G.M. Blockinger🇺🇸 · A. Kamaha🇺🇸 · N. Parveen🇺🇸 · G.R.C. Rischbieter🇺🇸

   The search for dark matter, the missing mass of the Universe, is one of the most active fields of study within particle physics. The XENON1T experiment recently observed a 3.5$\sigma$ excess potentially consistent with dark matter, or with solar axions. Here, we will use the Noble Element Simulation Technique (NEST) software to simulate the XENON1T detector, reproducing the excess. We utilize different detector efficiency and energy reconstruction models, but they primarily impact sub-keV energies and cannot explain the XENON1T excess. However, using NEST, we can reproduce their excess in multiple, unique ways, most easily via the addition of 31$\pm$11 ${}^{37}Ar$ decays. Furthermore, this results in new, modified background models, reducing the significance of the excess to $\le 2.2\sigma$ at least using non-Profile Likelihood Ratio (PLR) methods. This is independent confirmation that the excess is a real effect, but potentially explicable by known physics. Many cross-checks of our ${}^{37}Ar$ hypothesis are presented.

   ↳ hep-exnucl-exphysics.ins-detPRD(2021)·42 citations
4. 04*

   Precision tests of fundamental physics with $\eta$ and ${\eta }^{\prime }$ mesons

   Liping Gan🇺🇸 · Bastian Kubis🇩🇪 · Emilie Passemar🇺🇸 · Sean Tulin🇨🇦

   Decays of the neutral and long-lived $\eta$ and ${\eta }^{\prime }$ mesons provide a unique, flavor-conserving laboratory to test low-energy Quantum Chromodynamics and search for new physics beyond the Standard Model. They have drawn world-wide attention in recent years and have inspired broad experimental programs in different high-intensity-frontier centers. New experimental data will offer critical inputs to precisely determine the light quark mass ratios, $\eta$-${\eta }^{\prime }$ mixing parameters, and hadronic contributions to the anomalous magnetic moment of the muon. At the same time, it will provide a sensitive probe to test potential new physics. This includes searches for hidden photons, light Higgs scalars, and axion-like particles that are complementary to worldwide efforts to detect new light particles below the GeV mass scale, as well as tests of discrete symmetry violation. In this review, we give an update on theoretical developments, discuss the experimental opportunities, and identify future research needed in this field.

   ↳ hep-phhep-exnucl-exnucl-thPhys.Rept.(2022)·182 citations
5. 05*

   Study of a possibility of observation of hidden-bottom pentaquark resonances in bottomonium photoproduction on protons and nuclei near threshold

   E. Ya. Paryev🇷🇺

   We study the ${\rm Y}(1S)$ meson photoproduction on protons and nuclei at the near-threshold center-of-mass energies below 11.4 GeV (or at the corresponding photon laboratory energies $E_{\gamma }$ below 68.8 GeV). We calculate the absolute excitation functions for the non-resonant and resonant photoproduction of ${\rm Y}(1S)$ mesons off protons at incident photon laboratory energies of 63--68 GeV by accounting for direct ($\gamma p\to {\rm Y}(1S)p$) and two-step ($\gamma p\to P_b^{+}(11080,11125,11130)\to {\rm Y}(1S)p$) ${\rm Y}(1S)$ production channels within different scenarios for the non-resonant total cross section of elementary reaction $\gamma p\to {\rm Y}(1S)p$ and for branching ratios of the decays $P_b^{+}(11080,11125,11130)\to {\rm Y}(1S)p$. We also calculate an analogous functions for photoproduction of ${\rm Y}(1S)$ mesons on ${}^{12}$C and ${}^{208}$Pb target nuclei in the near-threshold center-of-mass beam energy region of 9.0--11.4 GeV by considering respective incoherent direct ($\gamma N\to {\rm Y}(1S)N$) and two-step ($\gamma p\to P_b^{+}(11080,11125,11130)\to {\rm Y}(1S)p$, $\gamma n\to P_b^0(11080,11125,11130)\to {\rm Y}(1S)n$) ${\rm Y}(1S)$ production processes within a nuclear spectral function approach. We show that a detailed scan of the ${\rm Y}(1S)$ total photoproduction cross section on a proton and nuclear targets in the near-threshold energy region in future high-precision experiments at the proposed high-luminosity electron-ion colliders EIC and EicC in the U.S. and China should give a definite result for or against the existence of the non-strange hidden-bottom pentaquark states $P_{bi}^{+}$ and $P_{bi}^0$ ($i=$1, 2, 3) as well as clarify their decay rates.

   ↳ nucl-thhep-phnucl-ex18 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.