Nuclear Theory·nucl-th

Friday·March 6, 2020

13 papers—7 primary·6 cross-listed

08
How long does the hydrogen atom live?
David McKeen🇨🇦 · Maxim Pospelov🇺🇸
It is possible that the proton is stable while atomic hydrogen is not. This is the case in models with new particles carrying baryon number which are light enough to be stable themselves but heavy enough so that proton decay is kinematically blocked. Models of new physics that explain the neutron lifetime anomaly generically have this feature, allowing for atomic hydrogen to decay through electron capture on a proton. We calculate the radiative hydrogen decay rate involving the emission of a few hundred keV photon, which makes this process detectable in experiment. In particular, we show that the low energy part of the Borexino spectrum is sensitive to radiative hydrogen decay, and turn this into a limit on the hydrogen lifetime of order $1 0^{30} s$ or stronger. For models where the neutron mixes with a dark baryon, $χ$ , this limits the mixing angle to roughly $1 0^{- 11}$ , restricting the $n \to χ γ$ branching to $1 0^{- 4}$ , over a wide range of parameter space.
↳ hep-phhep-exnucl-exnucl-thUniverse(2023)·31 citations
09
Soft Fragmentation on the Celestial Sphere
Duff Neill🇺🇸 · Felix Ringer🇺🇸
We develop two approaches to the problem of soft fragmentation of hadrons in a gauge theory for high energy processes. The first approach directly adapts the standard resummation of the parton distribution function's anomalous dimension (that of twist-two local operators) in the forward scattering regime, using $k_{T}$ -factorization and BFKL theory, to the case of the fragmentation function by exploiting the mapping between the dynamics of eikonal lines on transverse-plane to the celestial-sphere. Critically, to correctly resum the anomalous dimension of the fragmentation function under this mapping, one must pay careful attention to the role of regularization, despite the manifest collinear or infra-red finiteness of the BFKL equation. The anomalous dependence on energy in the celestial case, arising due to the mismatch of dimensionality between positions and angles, drives the differences between the space-like and time-like anomalous dimension of parton densities, even in a conformal theory. The second approach adapts an angular-ordered evolution equation, but working in 4-2 $ϵ$ dimensions at all angles. The two approaches are united by demanding that the anomalous dimension in 4-2 $ϵ$ dimensions for the parton distribution function determines the kernel for the angular-ordered evolution to all orders.
↳ hep-phhep-thnucl-thJHEP(2020)·27 citations
10
Testing Parameterizations of the Deuteron Quasi-Elastic Peak
Iu. A. Skorodumina · G. V. Fedotov · R. W. Gothe
This study introduces common parameterizations of the quasi-elastic peak in the electron scattering spectrum off deuterium and provides the comparison of the parameterized cross sections with published experimental data. The comparison is performed in the wide $Q^{2}$ range from $\sim$ 0.3 GeV $^{2}$ to $\sim$ 4 GeV $^{2}$ . In this way the performance of the parameterizations and their ability to describe experimental measurements are impartially tested and the conclusion on the description reliability is made.
↳ nucl-exnucl-th1 citation
11
An extended $R_{Ψ_{m}}^{(2)} (Δ S_{2})$ correlator for detecting and characterizing the Chiral Magnetic Wave
Niseem Magdy (1)🇺🇸 · Mao-Wu Nie (2,3)🇨🇳 · Ling Huang (4,5,6)🇨🇳 · Guo-Liang Ma (4,6)🇨🇳 · Roy. A. Lacey (7) ((1) Department of Physics, University of Illinois at Chicago, IL, USA, (2) Institute of Frontier and Interdisciplinary Science, Shandong University, China, (3) Key Laboratory of Particle Physics and Particle Irradiation, Ministry of Education, Shandong University, China, (4) Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, China, (5) University of Chinese Academy of Sciences, Beijing, China, (6) Key Laboratory of Nuclear Physics and Ion-beam Application (MOE), Institute of Modern Physics, Fudan University, Shanghai, China, (7) Depts. of Chemistry & Physics, Stony Brook University, Stony Brook, NY)🇺🇸
The extended $R_{Ψ_{m}}^{(2)} (Δ S_{2})$ correlator is presented and examined for its efficacy to detect and characterize the quadrupole charge separation ( $Δ S_{2}$ ) associated with the purported Chiral Magnetic Wave (CMW) produced in heavy-ion collisions. Sensitivity tests involving varying degrees of proxy CMW signals injected into events simulated with the Multi-Phase Transport Model (AMPT), show that the $R_{Ψ_{m}}^{(2)} (Δ S_{2})$ correlator provides discernible responses for the background- and CMW-driven charge separation. This distinction could aid identification of the CMW via measurements of the $R_{Ψ_{2}}^{(2)} (Δ S_{2})$ and $R_{Ψ_{3}}^{(2)} (Δ S_{2})$ correlators, relative to the second- ( $Ψ_{2}$ ) and third-order ( $Ψ_{3}$ ) event planes. The tests also indicate a level of sensitivity that would allow for robust experimental characterization of the CMW signal.
↳ nucl-exhep-exhep-phnucl-thPLB(2020)·6 citations
12
$γ$ -hadron spectra in p + Pb collisions at $s_{NN} = 5.02$ TeV
Man Xie🇨🇳 · Xin-Nian Wang🇨🇳 · Han-Zhong Zhang🇨🇳
Under the assumption that a quark-gluon plasma droplet is produced and its evolution can be described by hydrodynamics in p + A collisions, $γ$ -triggered hadron spectra are studied within a next-to-leading-order perturbative QCD parton model with the medium-modified parton fragmentation functions. The initial conditions and space-time evolution of the small QGP droplet are provided by the superSONIC hydrodynamic model simulations and parton energy loss in such a medium is described by the high-twist (HT) approach. The scaled jet transport coefficient $q^/ T^{3}$ in this HT approach is extracted from single hadron suppression in central A + A collisions at the same colliding energy. Numerical results for this scenario show that $γ$ -hadron spectra at $p_{T}^{γ} = 12 - 40$ GeV/ $c$ are suppressed by 5\% $\sim$ 10\% in the most central 0 - 10\% p + Pb collisions at $s_{NN} = 5.02$ TeV. The suppression becomes weaker at higher transverse momentum of the $γ$ trigger. As a comparison, $γ$ -hadron suppression in Pb + Pb collisions at $s_{NN} = 2.76$ and 5.02 TeV is also predicted.
↳ hep-phnucl-thPRC(2021)·28 citations
13
Relativistic Dynamics of Fluctuations and QCD Critical Point
Xin An🇺🇸
We review the recent development on a systematic deterministic formalism describing dynamics of both bulk and fluctuations in an arbitrary relativistic hydrodynamic flow carrying conserved charges. In particular, we discuss the implementation of such general formalism near the QCD critical point.
↳ hep-thcond-mat.stat-mechhep-phnucl-thNPA(2021)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE

How long does the hydrogen atom live?

Soft Fragmentation on the Celestial Sphere

Testing Parameterizations of the Deuteron Quasi-Elastic Peak

An extended RΨm​(2)​(ΔS2​) correlator for detecting and characterizing the Chiral Magnetic Wave

γ-hadron spectra in p + Pb collisions at sNN​​=5.02 TeV

Relativistic Dynamics of Fluctuations and QCD Critical Point

Affiliations

An extended $R_{Ψ_{m}}^{(2)} (Δ S_{2})$ correlator for detecting and characterizing the Chiral Magnetic Wave

$γ$ -hadron spectra in p + Pb collisions at $s_{NN} = 5.02$ TeV