Hadron spectroscopy at STCF

Abstract

I. INTRODUCTIONDespite that quantum chromodynamics (QCD), the theory of strong interaction, has colorful quarks and gluons as its basic degrees of freedom, all fundamental particles participating the strong interaction that can be directly detected in experiments are colorless or color-singlet hadrons. This phenomenon is called color confinement. Because of that, the study of hadron spectroscopy is essential in improving our understanding of the nonperturbative regime of QCD and to reveal the mechanism of color confinement. The high-luminosity electron-positron collision machine under discussion, Super τ -Charm Facility (STCF), can play an essential role in hadron spectroscopy by discovering new hadron resonances and measuring properties of known hadrons with an unprecedented precision. In the following, we will discuss briefly the topics on hadron spectroscopy that will be investigated at STCF. II. PHYSICS LANDSCAPE A. Highly excited charmonia and charmonium-like statesCharmonium states being bound states of a charm and an anticharm quark were supposed to be well described by nonrelativistic potential quark models [1,2]. This was the case before 2003.Since the discovery of the X(3872), also known as χ c1 (3872), by Belle in 2003 [3], there have been a large number of new resonance(-like) structures observed in the charmonium mass region by various experiments, including BESIII, BaBar, Belle, CDF, D0, ATLAS, CMS and LHCb (see e.g.

Triply heavy baryons in the constituent quark model *

“…At the same time, an enormous theoretical effort with a wide variety of approaches has been carried out in order to reveal the nature of exotic hadrons. Generally, there are extensive reviews [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29], which explain in detail a particular theoretical method and thus capture a certain interpretation of exotic states.…”

Bottomoniumlike tetraquarks in a chiral quark model

“…From the theoretical side, an enormous effort devoted to reveal the nature of the unexpected exotic hadrons has been deployed using a wide variety of approaches. In fact, one can already find in the literature many extensive reviews [17][18][19][20][21][22][23][24][25][26][27][28][29][30], which explain in detail a particular theoretical method and thus capture a certain interpretation of the XY Z states. One can find either compact or molecular tetraquark interpretaions, or even relate the signals with simple kinematical effects such as cusps.…”