14361404
Properties of nuclear matter in a nonlinear realized approach of the SU(2) chiral symmetry spontaneous breaking
A nonlinear realization of SU(2) chiral symmetry spontaneous breaking approach is developed in the composite operator formalism. The properties of nuclear matter, the pion and the quark condensates in nuclear matter are evaluated. The calculated results show that the saturation properties of nuclear matter can be reproduced well with the approach. Meanwhile, the expectation value of ~π 2 becomes nonzero in the nuclear matter with minimal density ρN ∼ 0.235fm−3, and the quark condensate decreases monotonously with the increasing of the nuclear matter density. As the pion condensate appears, the decreasing rate of the quark condensate is enhanced. PACS numbers : 11.30.Rd, 11.30.Qc, 12.39.Fe,21.65.+f
117634870
Some properties of pi meson in nuclear matter with finite density
In the GCM we study some properties of pi meson as the Goldstone bosons in a nuclear matter with finite density. Using the effective action in a nuclear matter, we calculate the decay constant and pi mass as functions of the chemical potential. The relation between the chemical potential and the density of a nuclear matter is firstly given here. We find that f(pi) and m(pi) monotonously decrease as nuclear matter density increases. The result is consistent with the usual assumption that the chiral symmetry is gradually restored as the density of a nuclear matter increases.
121445421
Study of Topological Structure of Vacuum by Lattice QCD
Overlap fermions and improved 5Li cooling are compared, which exhibits that these two filter methods can produce similar structures. Then the overlap fermions and improved 5Li cooling are combined to calculate the topological charge and identify the structure of the vacuum. The results are consistent with instanton liquid model.
124731696
The effective gluon propagator in the global color symmetry model
It is shown that the effective gluon propagator in the global color symmetry model can be calculated in the instanton dilute liquid approximation. The calculated effective gluon propagator is consistent with the general command on the qualitative features of the gluon propagator, i.e., (i) the gluon propagator is significantly enhanced at small space-like k(2), and (ii) for k(2) > 1.5 GeV2 the perturbative results are quantitatively reliable.
123819304
QCD INTERACTION IN PION-DEUTERON ELASTIC-SCATTERING
The pion-deuteron elastic scattering matrix element is under consideration in the framework of QCD. The interactions including the perturbative effect and nonperturbative contributions of gluon condensate and quark condensate in the scattering process are discussed. The interaction operators are given.
119391728
Quantum Version of Gauge Invariance and Nucleon Internal Structure
The conflict between cononical commutation relation and gauge invariance, which both the momentum and angular momentum of quark and gluon should satisfy, is clarified. The quantum version of gauge invariance is studied. The gauge independence of the matrix elements of quark momentum and angular momentum operators between physical states are proved. We suggest to use the canonical quark momentum and angular momentum distributions to describe the nucleon internal structure in order to establish an internal consistent description of hadron spectroscopy and hadron structure. The same problem for the atomic spectroscopy and structure is discussed.
119116044
Energy loss signals in the ALICETRD
Abstract We present the energy loss measurements with the ALICE TRD in the β γ range 1–10 4 , where β = v / c and γ = 1 / 1 − β 2 . The measurements are conducted in three different scenarios: (1)with pions and electrons from testbeams; (2)with protons, pions and electrons in proton–proton collisions at center-of-mass energy 7 TeV; (3)with muons detected in ALICE cosmic runs. In the testbeam and cosmic ray measurements, ionization energy loss (d E /d x ) signal as well as ionization energy loss plus transition radiation (d E /d x +TR) signal are measured. With cosmic muons the onset of TR is observed. Signals from TeV cosmic muons are consistent with those from GeV electrons in the other measurements. Numerical descriptions of the signal spectra and the β γ - dependence of the most probable signals are also presented.
118605527
How to use the Standard Model effective field theory
A bstractWe present a practical three-step procedure of using the Standard Model effective field theory (SM EFT) to connect ultraviolet (UV) models of new physics with weak scale precision observables. With this procedure, one can interpret precision measurements as constraints on a given UV model. We give a detailed explanation for calculating the effective action up to one-loop order in a manifestly gauge covariant fashion. This covariant derivative expansion method dramatically simplifies the process of matching a UV model with the SM EFT, and also makes available a universal formalism that is easy to use for a variety of UV models. A few general aspects of RG running effects and choosing operator bases are discussed. Finally, we provide mapping results between the bosonic sector of the SM EFT and a complete set of precision electroweak and Higgs observables to which present and near future experiments are sensitive. Many results and tools which should prove useful to those wishing to use the SM EFT are detailed in several appendices.
119681467
Exploring the performance limits of the ALICE Time Projection Chamber and Transition Radiation Detector for measuring identified hadron production at the LHC
The Time Projection Chamber (TPC) and Transition Radiation Detector (TRD) are the 
main tracking and particle identification devices in the ALICE experiment at the CERN 
LHC. This thesis studies aspects of their performance beyond the original designs. This 
includes extending the TPC momentum measurement for cosmic rays to sub-TeV scale, 
investigating a robust identification method for electrons and hadrons by the TRD, and 
developing new approaches to characterize the TPC and TRD signals. These studies lead 
to an intriguing observation of the transition radiation from sub-TeV cosmic muons, and 
a universal method -- the TPC coherent fit -- to extract yields of different particle species 
with momentum from 0.5 to above 20 GeV/c. 
 
With the TPC coherent fit, transverse momentum spectra (0.6 < pt < 20 GeV/c) of pions, 
kaons and protons at mid-rapidity (|y|<~0.8) in pp collisions at sqrt(s) = 2.76 and 7 TeV and 
Pb-Pb collisions at sqrt(s_NN) = 2.76 TeV at the LHC are measured. In this unified approach 
both the anomalous enhancement of the proton-to-pion ratio at moderate pt (2-8 GeV/c) 
(the so-called baryon anomaly) and the nuclear modification of particle yields up to 
high pt (> 10 GeV/c) in Pb-Pb collisions are observed. The particle production is also 
studied in jets from pp collisions at 7 TeV and the results are well described by Perugia-0 
tune of PYTHIA6.
120618992
Eigenvalue Distribution of Large $N$ Random Matrix--- A Direct Diagrammatic Proof to Marchenko-Pastur Law ---
In various theoretical models, large N limit has been a very useful tool, both at a qualitative and a quantitative level [1]. It works as a great approximation, even when the actual dimension of the matrix is not a very large number, such as Nc = 3 in QCD [2, 3] and Nf = 3 in neutrino anarchy [4]. It is thus useful to understand the behavior of large N random matrices as much as possible. In random matrix theory, there is a powerful law— Marchenko-Pastur (MP) law [5]—that governs the asymptotic eigenvalue distribution of large-dimension random matrices. In this paper we provide an alternative proof to it. We first state Marchenko Pastur law in Section II. Then in Section III, we present a detailed proof of MP law using Feynman diagrams. We extend our proof to symmetric matrix case in Section IV. Section V is our conclusion.
20926318
Natural Higgs mass in supersymmetry from nondecoupling effects.
The Higgs mass implies fine-tuning for minimal theories of weak-scale supersymmetry (SUSY). Nondecoupling effects can boost the Higgs mass when new states interact with the Higgs boson, but new sources of SUSY breaking that accompany such extensions threaten naturalness. We show that two singlets with a Dirac mass can increase the Higgs mass while maintaining naturalness in the presence of large SUSY breaking in the singlet sector. We explore the modified Higgs phenomenology of this scenario, which we call the "Dirac next-to-minimal supersymmetric standard model."