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Description of Baryon Mass Spectrum by Open Strings and Diquarks

Yuki Fujimoto

TL;DR

The paper investigates whether hadron mass spectra can be described by the open string Hagedorn spectrum with a single deconfinement scale $T_H$. It formulates the open string density of states $ ho_{ ext{str}}(m)$ with exponential growth $e^{m/T_H}$ and defines cumulative spectra for both mesons and baryons, establishing a framework where $T_H$ is tied to the string tension. Fitting to PDG data yields $T_H \approx 0.340$ GeV for mesons and $T_H \approx 0.341$ GeV for baryons, implying a common deconfinement temperature and supporting a quark-diquark description for baryons. The results align with lattice QCD expectations for the string tension and Regge slopes, reinforcing the open string approach as a robust description of hadron spectroscopy and informing QCD thermodynamics and the phase diagram at finite temperature and chemical potential.

Abstract

We analyze the mass spectra of hadrons and demonstrate that the physical spectra of mesons and baryons are well described by the exponential spectrum of open strings. The open string spectrum, derived from string theory, is characterized by a unique Hagedorn temperature $T_{\rm H}$ and free from any other parameters. Notably, our fitting to the physical spectra yields consistent values for both mesons and baryons, $T_{\rm H} \simeq 0.34\,\text{GeV}$, which contrasts with previous phenomenological analyses that suggested different values. This obtained value aligns well with typical string tension derived from lattice-QCD calculations and the Regge slope. In the baryonic sector, our results indicate that diquarks play a crucial role in describing the mass spectrum, implying that baryons can be understood as a quark-diquark system, as anticipated by Regge phenomenology. These findings have significant implications for our understanding of quark deconfinement, especially in the possibly existing regime at high temperature and small baryon chemical potential within the QCD phase diagram.

Description of Baryon Mass Spectrum by Open Strings and Diquarks

TL;DR

The paper investigates whether hadron mass spectra can be described by the open string Hagedorn spectrum with a single deconfinement scale . It formulates the open string density of states with exponential growth and defines cumulative spectra for both mesons and baryons, establishing a framework where is tied to the string tension. Fitting to PDG data yields GeV for mesons and GeV for baryons, implying a common deconfinement temperature and supporting a quark-diquark description for baryons. The results align with lattice QCD expectations for the string tension and Regge slopes, reinforcing the open string approach as a robust description of hadron spectroscopy and informing QCD thermodynamics and the phase diagram at finite temperature and chemical potential.

Abstract

We analyze the mass spectra of hadrons and demonstrate that the physical spectra of mesons and baryons are well described by the exponential spectrum of open strings. The open string spectrum, derived from string theory, is characterized by a unique Hagedorn temperature and free from any other parameters. Notably, our fitting to the physical spectra yields consistent values for both mesons and baryons, , which contrasts with previous phenomenological analyses that suggested different values. This obtained value aligns well with typical string tension derived from lattice-QCD calculations and the Regge slope. In the baryonic sector, our results indicate that diquarks play a crucial role in describing the mass spectrum, implying that baryons can be understood as a quark-diquark system, as anticipated by Regge phenomenology. These findings have significant implications for our understanding of quark deconfinement, especially in the possibly existing regime at high temperature and small baryon chemical potential within the QCD phase diagram.
Paper Structure (5 sections, 10 equations, 2 figures, 2 tables)

This paper contains 5 sections, 10 equations, 2 figures, 2 tables.

Table of Contents

  1. Introduction
  2. Mass spectra of hadrons and open strings
  3. String description of meson spectrum
  4. String description of baryon spectrum
  5. Summary and outlook

Figures (2)

  • Figure 1: The meson mass spectrum from PDG (blue dashed line) and the curve fitted by the open string formula (red curve). The shaded band corresponds to the varying values of $T_{\mathrm{H}}$ in the range $[0.285, 0.340]\,\text{GeV}$.
  • Figure 2: The baryon mass spectrum from PDG (blue dashed line) and the curve fitted by the open string formula (red curve). The shaded band corresponds to the varying values of $T_{\mathrm{H}}$ in the range $[0.285, 0.340]\,\text{GeV}$.