Nonperturbative QCD up to one-pion-loop for ρ−ω mixing and mass splitting

1995 ◽  
Author(s):  
K. L. Mitchell ◽  
P. C. Tandy ◽  
C. D. Roberts ◽  
R. T. Cahill
Keyword(s):  
Mass Splitting ◽  
Pion Loop ◽  
Nonperturbative Qcd

scholarly journals Importance of Nonperturbative QCD Parameters for Bottom Mesons

2014 ◽  
Vol 2014 ◽  
pp. 1-4
Author(s):  
A. Upadhyay ◽  
M. Batra
Keyword(s):  
Heavy Quark ◽  
Mass Splitting ◽  
Bottom Meson ◽  
Effective Theory ◽  
Heavy Quark Effective Theory ◽  
Flavor Symmetries ◽  
Fitted Parameter ◽  
Nonperturbative Qcd ◽  
Meson States ◽  
Theory Formula

The importance of nonperturbative quantum chromodynamics (QCD) parameters is discussed in context to the predicting power for bottom meson masses and isospin splitting. In the framework of heavy quark effective theory, the work presented here focuses on the different allowed values of the two nonperturbative QCD parameters used in heavy quark effective theory formula, and using the best fitted parameter, masses of the excited bottom meson states injp=1/2+doublet in strange and nonstrange sectors are calculated here. The calculated masses are found to be matching well with experiments and other phenomenological models. The mass splitting and hyperfine splitting have also been analyzed for both strange and nonstrange heavy mesons with respect to spin and flavor symmetries.

scholarly journals Pion loop contribution toρ-ωmixing and mass splitting

1997 ◽  
Vol 55 (3) ◽  
pp. 1477-1491 ◽  
Author(s):  
K. L. Mitchell ◽  
P. C. Tandy
Keyword(s):  
Mass Splitting ◽  
Loop Contribution ◽  
Pion Loop

Nonperturbative QCD and supersymmetric QCD

2004 ◽  
Vol 174 (2) ◽  
pp. 113 ◽  
Author(s):  
Viktor A. Novikov
Keyword(s):  
Nonperturbative Qcd

scholarly journals Xenon-1T excess as a possible signal of a sub-GeV hidden sector dark matter

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Amin Aboubrahim ◽  
Michael Klasen ◽  
Pran Nath
Keyword(s):  
Dark Matter ◽  
Particle Physics ◽  
Small Mass ◽  
Big Bang ◽  
Mass Splitting ◽  
Recoil Energy ◽  
Dirac Fermions ◽  
Dark Sector ◽  
Dark Photon ◽  
Physics Model

Abstract We present a particle physics model to explain the observed enhancement in the Xenon-1T data at an electron recoil energy of 2.5 keV. The model is based on a U(1) extension of the Standard Model where the dark sector consists of two essentially mass degenerate Dirac fermions in the sub-GeV region with a small mass splitting interacting with a dark photon. The dark photon is unstable and decays before the big bang nucleosynthesis, which leads to the dark matter constituted of two essentially mass degenerate Dirac fermions. The Xenon-1T excess is computed via the inelastic exothermic scattering of the heavier dark fermion from a bound electron in xenon to the lighter dark fermion producing the observed excess events in the recoil electron energy. The model can be tested with further data from Xenon-1T and in future experiments such as SuperCDMS.

scholarly journals Electroweak SU(2)L × U(1)Y model with strong spontaneously fermion-mass-generating gauge dynamics

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Petr Beneš ◽  
Jiří Hošek ◽  
Adam Smetana
Keyword(s):  
Chiral Symmetry Breaking ◽  
Axial Vector ◽  
Higgs Sector ◽  
Dyson Equation ◽  
Mass Splitting ◽  
Fermion Mass ◽  
Goldstone Bosons ◽  
The Standard Model ◽  
Exploratory Stage ◽  
The Masses

Abstract Higgs sector of the Standard model (SM) is replaced by quantum flavor dynamics (QFD), the gauged flavor SU(3)f symmetry with scale Λ. Anomaly freedom requires addition of three νR. The approximate QFD Schwinger-Dyson equation for the Euclidean infrared fermion self-energies Σf(p2) has the spontaneous-chiral-symmetry-breaking solutions ideal for seesaw: (1) Σf(p2) = $$ {M}_{fR}^2/p $$ M fR 2 / p where three Majorana masses MfR of νfR are of order Λ. (2) Σf(p2) = $$ {m}_f^2/p $$ m f 2 / p where three Dirac masses mf = m(0)1 + m(3)λ3 + m(8)λ8 of SM fermions are exponentially suppressed w.r.t. Λ, and degenerate for all SM fermions in f. (1) MfR break SU(3)f symmetry completely; m(3), m(8) superimpose the tiny breaking to U(1) × U(1). All flavor gluons thus acquire self-consistently the masses ∼ Λ. (2) All mf break the electroweak SU(2)L × U(1)Y to U(1)em. Symmetry partners of the composite Nambu-Goldstone bosons are the genuine Higgs particles: (1) three νR-composed Higgses χi with masses ∼ Λ. (2) Two new SM-fermion-composed Higgses h3, h8 with masses ∼ m(3), m(8), respectively. (3) The SM-like SM-fermion-composed Higgs h with mass ∼ m(0), the effective Fermi scale. Σf(p2)-dependent vertices in the electroweak Ward-Takahashi identities imply: the axial-vector ones give rise to the W and Z masses at Fermi scale. The polar-vector ones give rise to the fermion mass splitting in f. At the present exploratory stage the splitting comes out unrealistic.

scholarly journals Exothermic dark matter for XENON1T excess

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Hyun Min Lee
Keyword(s):  
Dark Matter ◽  
Mass Difference ◽  
Mass Splitting ◽  
Effective Theory ◽  
Recoil Energy ◽  
Detector Resolution ◽  
Atomic Excitation ◽  
Microscopic Models ◽  
Electron Recoil ◽  
Two Component

Abstract Motivated by the recent excess in the electron recoil from XENON1T experiment, we consider the possibility of exothermic dark matter, which is composed of two states with mass splitting. The heavier state down-scatters off the electron into the lighter state, making an appropriate recoil energy required for the Xenon excess even for the standard Maxwellian velocity distribution of dark matter. Accordingly, we determine the mass difference between two component states of dark matter to the peak electron recoil energy at about 2.5 keV up to the detector resolution, accounting for the recoil events over ER = 2 − 3 keV, which are most significant. We include the effects of the phase-space enhancement and the atomic excitation factor to calculate the required scattering cross section for the Xenon excess. We discuss the implications of dark matter interactions in the effective theory for exothermic dark matter and a massive Z′ mediator and provide microscopic models realizing the required dark matter and electron couplings to Z′.

scholarly journals More about the Mass of the New Charmonium States

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
T. M. Aliev ◽  
H. Özşahin ◽  
M. Savcı
Keyword(s):  
Sum Rules ◽  
Critical Role ◽  
Mass Splitting ◽  
Qcd Sum Rules ◽  
Experimental Search ◽  
New States ◽  
Charmonium States

IfX(3872)is described by the picture as a mixture of the charmonium and molecularD*Dstates;Y(3940)as a mixture of theχc0andD*D*states; andY(4260)as a mixture of the tetraquark and charmonium states, their orthogonal combinations should also exist. We estimate the mass and residues of the states within the QCD sum rules method. We find that the mass splitting amongX, Yand their orthogonal states is at most 200 MeV. Experimental search of these new states can play critical role for establishing the nature of the new charmonium states.

scholarly journals Pion-Quark Interaction and Baryon Mass Splitting

1985 ◽  
Vol 74 (3) ◽  
pp. 637-640 ◽  
Author(s):  
Y. Iwamura ◽  
Y. Nogami ◽  
N. Ohtsuka
Keyword(s):  
Mass Splitting ◽  
Quark Interaction ◽  
Baryon Mass
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