Mass of the Up Quark

1978 ◽  
Vol 41 (3) ◽  
pp. 139-141 ◽  
Author(s):  
A. Zepeda
Keyword(s):  
Up Quark

scholarly journals Is the up quark massless?

2002 ◽  
Vol 106-107 ◽  
pp. 221-223 ◽  
Author(s):  
Daniel Nelson ◽  
George Fleming ◽  
Greg Kilcup
Keyword(s):  
Up Quark

MEASUREMENT OF POLARIZED QUARK DISTRIBUTIONS AT HERMES

2003 ◽  
Vol 18 (08) ◽  
pp. 1185-1192
Author(s):  
◽  
STEFAN BERNREUTHER
Keyword(s):  
Cross Section ◽  
Kinematic Range ◽  
Spin Asymmetries ◽  
Double Spin ◽  
Hermes Experiment ◽  
Down Quark ◽  
Up Quark ◽  
Rich Detector ◽  
The Individual ◽  
Quark Flavors

The HERMES experiment has measured double spin asymmetries in the cross section for deep–inelastic scattering of longitudinally polarized positrons on longitudinally polarized 3 He (1995), 1 H (1996/97), and 2 D (1998) targets. A kinematic range of 0.023 < x < 0.6, and 1 GeV 2 < Q2 < 15 GeV 2 has been covered. From these asymmetries, based on inclusive and semi–inclusive measurements, polarized quark distributions are extracted as a function of x for up [Formula: see text] and down [Formula: see text] flavors as well as for valence and sea quarks. In the measured range, the up quark polarization is positive while the down quark polarization is negative. The sea quark polarization is compatible with zero. In this analysis all sea quark polarizations have been assumed to be flavor symmetric. Presently HERMES is analyzing a high statistics 2 D data sample taken in 1999-2000. For these data it is possible to identify pions and kaons with a RICH detector which was installed in 1998. This will enable an extraction of the individual sea quark flavors [Formula: see text], [Formula: see text], and [Formula: see text] without any symmetry assumptions.

scholarly journals Topological susceptibility with a single light quark flavour

2018 ◽  
Vol 175 ◽  
pp. 14017 ◽  
Author(s):  
Julien Frison ◽  
Ryuichiro Kitano ◽  
Norikazu Yamada
Keyword(s):  
Quark Mass ◽  
Continuum Limit ◽  
Light Quark ◽  
The Other ◽  
Theoretical Argument ◽  
Up Quark ◽  
Order Of Magnitude ◽  
Quark Flavour ◽  
Definition Of ◽  
The Continuum

One of the historical suggestions to tackle the strong CP problem is to take the up quark mass to zero while keeping md finite. The θ angle is then supposed to become irrelevant, i.e. the topological susceptibility vanishes. However, the definition of the quark mass is scheme-dependent and identifying the mu = 0 point is not trivial, in particular with Wilson-like fermions. More specifically, up to our knowledge there is no theoretical argument guaranteeing that the topological susceptibility exactly vanishes when the PCAC mass does. We will present our recent progresses on the empirical check of this property using Nf = 1 + 2 flavours of clover fermions, where the lightest fermion is tuned very close to [see formula in PDF] and the mass of the other two is kept of the order of magnitude of the physical ms. This choice is indeed expected to amplify any unknown non-perturbative effect caused by mu ≠ md. The simulation is repeated for several βs and those results, although preliminary, give a hint about what happens in the continuum limit.

scholarly journals An approach to the instanton effect in B system

2018 ◽  
Vol 33 (02) ◽  
pp. 1850017
Author(s):  
Noriaki Kitazawa ◽  
Yuki Sakai
Keyword(s):  
Mass Spectrum ◽  
Chiral Symmetry Breaking ◽  
Light Quark ◽  
Heavy Meson ◽  
Effective Theory ◽  
Meson Mass ◽  
Quark Masses ◽  
Quark Interaction ◽  
Up Quark ◽  
Instanton Effect

We discuss the constraint on the size of QCD instanton effects in low-energy effective theory. Among various instanton effects in meson mass spectrum and dynamics, we concentrate on the instanton-induced masses of light quarks. The famous instanton-induced six-quark interaction, so-called ’t Hooft vertex, could give nonperturbative quantum corrections to light quark masses. Many works have already been achieved to constrain the mass corrections in light meson system, or the system of [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], and now we know for a fact that the instanton-induced mass of up-quark is too small to realize the solution of the strong CP problem by vanishing current mass of up-quark. In this work, we give a constraint on the instanton-induced mass correction to light quarks from the mass spectrum of heavy mesons, [Formula: see text], [Formula: see text], [Formula: see text] and their antiparticles. To accomplish this, the complete second-order chiral symmetry breaking terms are identified in heavy meson effective theory. We find that the strength of the constraint from heavy meson masses is at the same level of that from light mesons, and it would be made even stronger by more precise data from future [Formula: see text] factories and lattice calculations.

scholarly journals Up Quark Mass in Lattice QCD with Three Light Dynamical Quarks and Implications for StrongCPInvariance

2003 ◽  
Vol 90 (2) ◽  
Author(s):  
Daniel R. Nelson ◽  
George T. Fleming ◽  
Gregory W. Kilcup
Keyword(s):  
Lattice Qcd ◽  
Quark Mass ◽  
Up Quark

scholarly journals SUFFICIENTLY SMALL $\bar\theta$inSU(3)3 × S3 UNIFICATION MODEL

2002 ◽  
Vol 17 (23) ◽  
pp. 1513-1524 ◽  
Author(s):  
K. CHALUT ◽  
H. CHENG ◽  
P. H. FRAMPTON ◽  
K. STOWE ◽  
T. YOSHIKAWA
Keyword(s):  
Dipole Moment ◽  
Cp Violation ◽  
Electric Dipole ◽  
High Energy ◽  
Neutron Electric Dipole Moment ◽  
Standard Model Extension ◽  
Weak Decays ◽  
Up Quark ◽  
Model Extension ◽  
The Standard Model

Since CP violation in weak decays is successfully described by the KM mechanism, the strong CP problem cannot be easily accommodated. This leads us to reconsider the issue. If the axion and massless up quark are abandoned, we must extend the standard model. Extension to SU (3)3 × S3 unification leads to the following situation: if CP is a high-energy symmetry and the appropriate symmetry-breaking hierarchy of scales is in place, then the [Formula: see text] parameter of the QCD sub-theory is guaranteed to be sufficiently small. We find [Formula: see text] while the empirical limit from the neutron electric dipole moment requires only that [Formula: see text].

scholarly journals Is the up-quark massless?

2001 ◽  
Vol 518 (3-4) ◽  
pp. 243-251 ◽  
Author(s):  
A.C Irving ◽  
C McNeile ◽  
C Michael ◽  
K.J Sharkey ◽  
H Wittig
Keyword(s):  
Up Quark

scholarly journals BOUNDS FOR NEUTRINOLESS DOUBLE BETA DECAY IN SO(10) INSPIRED SEESAW MODELS

2004 ◽  
Vol 19 (40) ◽  
pp. 2993-3000 ◽  
Author(s):  
F. BUCCELLA ◽  
D. FALCONE
Keyword(s):  
Gauge Theory ◽  
Matrix Element ◽  
Beta Decay ◽  
Neutrino Mass ◽  
Quark Mass ◽  
Mass Matrix ◽  
Neutrinoless Double Beta Decay ◽  
Double Beta Decay ◽  
Up Quark ◽  
The Matrix

By requiring the lower limit for the lightest right-handed neutrino mass, obtained in the baryogenesis from leptogenesis scenario, and a Dirac neutrino mass matrix similar to the up-quark mass matrix, we predict small values for the νe mass and for the matrix element mee responsible of the neutrinoless double beta decay, mνe around 5×10-3 eV and mee smaller than 10-3 eV , respectively. The allowed range for the mass of the heaviest right-handed neutrino is centered around the value of the scale of B–L breaking in the SO (10) gauge theory with Pati–Salam intermediate symmetry.

Is the Up-Quark Mass Zero?

1978 ◽  
Vol 41 (11) ◽  
pp. 735-738 ◽  
Author(s):  
Nilendra G. Deshpande ◽  
Davison E. Soper
Keyword(s):  
Quark Mass ◽  
Up Quark
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