摘要 :
I discuss heavy flavor production at hadronic facilities. I present total cross sections and differ_ential distributions for top quark, bottom quark, and charm quark production at the Tevatron and LHC colliders, and at fixed-targe...
展开
I discuss heavy flavor production at hadronic facilities. I present total cross sections and differ_ential distributions for top quark, bottom quark, and charm quark production at the Tevatron and LHC colliders, and at fixed-target experiments such as HERA-B. The calculations include complete next-to-leading order corrections as well as higher-order soft-gluon corrections which are important near kinematical threshold.
收起
摘要 :
Two kinds of difficulties have challenged the physics community for many years: (1) knowing nature's building blocks (particle physics) and (2) understanding interacting many-body systems (many-body physics). Both of them exist in...
展开
Two kinds of difficulties have challenged the physics community for many years: (1) knowing nature's building blocks (particle physics) and (2) understanding interacting many-body systems (many-body physics). Both of them exist in the research of quark matter and compact stars. This paper addresses the possibility that quark clustering, rather than a color super_conducting state, could occur in cold quark matter at realistic baryon densities of compact stars, since a weakly coupling treatment of the interaction between quarks might not be reliable. Cold quark matter is conjectured to be in a solid state if thermal kinematic energy is much lower than the interaction energy of quark clusters. Different manifestations of pulsar-like compact stars are discussed, as well as modeled in a regime of solid quark stars.
收起
摘要 :
Recent theoretical and experimental improvements in the determination of charm- and bottom-quark masses are discussed. The final results, m_c(3GeV) = 986(13) MeV and m_b(m_b) = 4163(16) MeV represent the presently most precise det...
展开
Recent theoretical and experimental improvements in the determination of charm- and bottom-quark masses are discussed. The final results, m_c(3GeV) = 986(13) MeV and m_b(m_b) = 4163(16) MeV represent the presently most precise determinations of these two fundamental Standard Model parameters.
收起
摘要 :
We review recent results on the phase structure of quantum chromodynamics (QCD) and bulk QCD thermodynamics. In particular, we discuss how universal critical scaling related to spontaneous breaking of the chiral symmetry manifests...
展开
We review recent results on the phase structure of quantum chromodynamics (QCD) and bulk QCD thermodynamics. In particular, we discuss how universal critical scaling related to spontaneous breaking of the chiral symmetry manifests itself in recent lattice QCD simulations and how the knowledge on non-universal scaling parameters can be utilized in the exploration of the QCD phase diagram. We also show how various (generalized) susceptibilities can be employed to characterize properties of QCD matter at low and high temperatures, related to deconfining aspects of the QCD transition. Finally, we highlight the recent efforts towards understanding how lattice QCD calculation can provide input for our understanding of the matter created in heavy ion collisions and in particular on the freeze-out conditions met in the hydrodynamic evolution of this matter.
收起
摘要 :
Search for new-physics through possible anomalous ttγ, tbW and γγH couplings which are generated by SU(2) x U(1) gauge-invariant dimension-6 effective operators is discussed, using energy and angular distributions of final char...
展开
Search for new-physics through possible anomalous ttγ, tbW and γγH couplings which are generated by SU(2) x U(1) gauge-invariant dimension-6 effective operators is discussed, using energy and angular distributions of final charged-lepton/b-quark in γγ → tt → lX/bX for various beam polarizations. Optimal beam polarizations that minimize uncertainty in determination of those non-standard couplings are found performing an optimal-observable analysis.
收起
摘要 :
We consider the possibility of using tt production at photon colliders as a probe for physics beyond the Standard Model. The angular and energy distributions of top-quark decay products are employed in the analysis that determines...
展开
We consider the possibility of using tt production at photon colliders as a probe for physics beyond the Standard Model. The angular and energy distributions of top-quark decay products are employed in the analysis that determines the accuracy with which the new physics parameters can be measured.
收起
摘要 :
Electroweak dipole operators in the standard-model-effective-field theory (SMEFT) are important indirect probes of quantum effects of new physics beyond the standard model (SM), yet they remain poorly constrained by current experi...
展开
Electroweak dipole operators in the standard-model-effective-field theory (SMEFT) are important indirect probes of quantum effects of new physics beyond the standard model (SM), yet they remain poorly constrained by current experimental analyses for lack of interference with the SM amplitudes in constructing cross section observables. In this Letter, we point out that dipole operators flip fermion helicities and so are ideally studied through single transverse spin asymmetries. We illustrate this at a future electron-positron collider with transversely polarized beams, where such an effect exhibits as azimuthal cos. and sin. distributions which originate from the interference of the electron dipole operators with the SM and are linearly dependent on their Wilson coefficients. This new method can improve the current constraints on the electron dipole couplings by 1-2 orders of magnitude, without depending on other new physics operators, and can also simultaneously constrain both their real and imaginary parts, offering a new opportunity for probing potential CP-violating effects.
收起
摘要 :
The quark model has a long history. The notion of quarks was introduced on the basis of unitary symmetry SU(3) for hadrons. This tradition lasts in the modern books on particle physics. We want to mention that quark's fractional c...
展开
The quark model has a long history. The notion of quarks was introduced on the basis of unitary symmetry SU(3) for hadrons. This tradition lasts in the modern books on particle physics. We want to mention that quark's fractional charge follows only from the compound nature of hadrons without any references to some symmetry. The constituent quarks must be fermions, and because charge is additive physical quantity, the sum of quarks' charge must be equal to the total charge of hadron. Normalization is chosen on charges of proton and neutron. The obtained linear system of equations is simply solvable and the solutions give the true values for quarks' charge. Therefore, this approach seems to be much more simple and do not require consideration of some methods of group theory. We consider this approach more simple and reasonable for student understanding.
收起
摘要 :
The PHENIX experiment has measured, J/ψ, ψ′ and γ productions for different collision systems in the forward rapidities 1.2 < | η | < 2.2 at $\sqrt {S_{NN} } $ = 200 GeV. We have observed significant suppressions of J/ψ prod...
展开
The PHENIX experiment has measured, J/ψ, ψ′ and γ productions for different collision systems in the forward rapidities 1.2 < | η | < 2.2 at $\sqrt {S_{NN} } $ = 200 GeV. We have observed significant suppressions of J/ψ production in both Cu+Cu and Au+Au collisions relative to the yield in p+p system. The measurements of higher mass heavy quarkonia states (ψ′ and γ) will help us to constrain various quarkonium suppression models in heavy ion collisions. A first hint of ψ′ and γ productions in 200GeV p+p collisions has been observed at forward and backward rapidities at PHENIX.
收起
原文获取