Nuclear Theory·nucl-th

Wednesday·August 26, 2015

8 papers—4 primary·4 cross-listed

05
[Submitted on 23 Aug 2015] (cross-list from hep-ph)
Strong Decays of Charmed Baryons in Heavy Hadron Chiral Perturbation Theory: An Update
Hai-Yang Cheng🇹🇼 · Chun-Khiang Chua🇹🇼
We first give a brief overview of the charmed baryon spectroscopy and discuss their possible structure and spin-parity assignments in the quark model. With the new Belle measurement of the widths of $Σ_{c} (2455)$ and $Σ_{c} (2520)$ and the recent CDF measurement of the strong decays of $Λ_{c} (2595)$ and $Λ_{c} (2625)$ , we give updated coupling constants in heavy hadron chiral perturbation theory. We find $g_{2} = 0.56 5_{- 0.024}^{+ 0.011}$ for $P$ -wave transitions between $s$ -wave and $s$ -wave baryons, and $h_{2}$ , one of the couplings responsible for $S$ -wave transitions between $s$ -wave and $p$ -wave baryons, is extracted from $Λ_{c} (2595)^{+} \to Λ_{c}^{+} π π$ to be $0.63 \pm 0.07$ . It is substantially enhanced compared to the old value of order 0.437. With the help from the quark model, two of the couplings $h_{10}$ and $h_{11}$ responsible for $D$ -wave transitions between $s$ -wave and $p$ -wave baryons are determined from $Σ_{c} (2880)$ decays. There is a tension for the coupling $h_{2}$ as its value extracted from $Λ_{c} (2595)^{+} \to Λ_{c}^{+} π π$ will imply $Ξ_{c} (2790)^{0} \to Ξ_{c}^{'} π$ and $Ξ_{c} (2815)^{+} \to Ξ_{c}^{*} π$ rates slightly above the current limits. It is conceivable that SU(3) flavor symmetry breaking can help account for the discrepancy.
Comments:
18 pages, 1 figure. References added, to appear in Phys. Rev. D. arXiv admin note: text overlap with arXiv:1508.07233, arXiv:hep-ph/0610283
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1508.05653 [pdf]
PRD(2015)·105 citations
06
[Submitted on 25 Aug 2015] (cross-list from hep-ph)
Chiral dynamics of S-wave baryon resonances
Bingwei Long🇨🇳
As the pion mass approaches a critical value $m_{π}^{⋆}$ from below, an $S$ -wave resonance crosses pion-baryon threshold and becomes a bound state with arbitrarily small binding energy, thus driving the scattering length to diverge. I explore the consequences of chiral symmetry for the values of $m_{π}$ close to $m_{π}^{⋆}$ . It turns out that chiral symmetry is crucial for an $S$ -wave resonance to be able to stand very near threshold and in the meantime to remain narrow, provided that the mass splitting is reasonably small. The effective range of pion-baryon scattering is unexpectedly large, proportional to $4 π f_{π}^{2} / m_{π}^{3}$ when $m_{π}$ is around $m_{π}^{⋆}$ . As a result, this unexpected large length scale causes universality relations to break down much sooner than naively expected.
Comments:
12 pages, 2 figures. The introductory text was modified. Matches the published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1508.06084 [pdf]
PRD(2016)·8 citations
07
[Submitted on 25 Aug 2015] (cross-list from hep-ph)
Antiproton-proton interaction and related hadron physics
Xian-Wei Kang🇩🇪
Antinucleon-nucleon interaction has been established in chiral effective field theory. The strong threshold enhancement observed in the reactions $J / ψ \to γ p p$ and $e^{+} e^{-} \to p p$ are interpreted by the strong $p p$ interaction. Concerning the channel $J / ψ \to γ p p$ , the topic on the $p p$ bound state is also discussed.
Comments:
9 pages, 5 figures, prepared for proceeding of the conference "Chiral Dynamics 2015", held from 29 June 2015 to 03 July 2015, Pisa, Italy
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1508.06189 [pdf]
PoS(2016)·2 citations
08
[Submitted on 25 Aug 2015] (cross-list from hep-ph)
Dilepton rate and quark number susceptibility with the Gribov action
Aritra Bandyopadhyay🇮🇳 · Najmul Haque🇺🇸 · Munshi G. Mustafa🇮🇳 · Michael Strickland🇺🇸
We use a recently obtained resummed quark propagator at finite temperature which takes into account both the chromoelectric scale gT and the chromomagnetic scale g^2T through the Gribov action. The electric scale generates two massive modes whereas the magnetic scale produces a new massless spacelike mode in the medium. Moreover, the non-perturbative quark propagator is found to contain no discontinuity in contrast to the standard perturbative hard thermal loop approach. Using this non-perturbative quark propagator and self-consistent vertices, we compute the non-perturbative dilepton rate at vanishing three-momentum at one-loop order. The resulting rate has a rich structure at low energies due to the inclusion of the non-perturbative magnetic scale. We also calculate the quark number susceptibility, which is related to the conserved quark number density fluctuation in the deconfined state. Both the dilepton rate and quark number susceptibility are compared with results from lattice quantum chromodynamics and the standard hard thermal loop approach. Finally, we discuss how the absence of a discontinuity in the imaginary part of the non-perturbative quark propagator makes the results for both dilepton production and quark number susceptibility dramatically different from those in perturbative approaches and seemingly in conflict with known lattice data.
Comments:
30 pages, 7 figures; v2 - version accepted for publication in PRD
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1508.06249 [pdf]
PRD(2016)·47 citations

Affiliations

first authorsco-authorsvia INSPIRE

Strong Decays of Charmed Baryons in Heavy Hadron Chiral Perturbation Theory: An Update

Chiral dynamics of S-wave baryon resonances

Antiproton-proton interaction and related hadron physics

Dilepton rate and quark number susceptibility with the Gribov action

Affiliations