We analyze the isospin-breaking corrections to quark condensates within one-loop SU(2) and SU(3) Chiral Perturbation Theory including $m_u\neq m_d$ as well as electromagnetic (EM) contributions. The explicit expressions are given and several phenomenological aspects are studied. We analyze the sensitivity of recent condensate determinations to the EM low-energy constants (LEC). If the explicit chiral symmetry breaking induced by EM terms generates a ferromagnetic-like response of the vacuum, as in the case of quark masses, the increasing of the order parameter implies constraints for the EM LEC, which we check with different estimates in the literature. In addition, we extend the sum rule relating quark condensate ratios in SU(3) to include EM corrections, which are of the same order as the $m_u\neq m_d$ ones, and we use that sum rule to estimate the vacuum asymmetry within ChPT. We also discuss the matching conditions between the SU(2) and SU(3) LEC involved in the condensates, when both isospin-breaking sources are taken into account.
Disoriented Chiral Condensates and Quantum Mechanical Isospin Correlation
经典的考虑表明概率分布$P(R)$,其中$R$是从无序手性凝聚体(假设在重离子反应中形成)发射的中性π介子与总π介子的比率,为$R^{-1/2}/2$。凝聚态和系统其余部分之间的量子力学同位旋相关性可以改变这一点。P(R)分布的矩可以用$(I^2/N^2)^m$的期望值来表示,其中$I$是凝聚体携带的同位旋,$N$是发射的π介子数,m是任意整数。我们发现,除非凝聚体携带的同位旋很大,否则它的几率分布与$0.1 < R < 0.9$的经典分布非常相似。
We calculate the light quark condensate, the strange quark condensate, the pion condensate, and the axial condensate in three-flavor chiral perturbation theory ($χ$PT) in the presence of an isospin chemical potential at next-to-leading order at zero temperature. It is shown that the three-flavor $χ$PT effective potential and condensates can be mapped onto two-flavor $χ$PT ones by integrating out mesons with strange quark content (kaons and eta), with renormalized couplings. We compare the results for the light quark and pion condensates at finite pseudoscalar source with ($2+1$)-flavor lattice…
We compute the density dependence of the quark condensate and how it changes under the influence of isospin-asymmetric nuclear matter. This is achieved by the calculation of the relevant Feynman diagrams using in-medium chiral perturbation theory. We find that the absolute value of the quark condensate decreases in nuclear matter by around 35% at normal nuclear density, in agreement with previous model-independent calculations. We also present an quantitative estimation of the difference of up- and down quark in-medium condensates.
我们分析了夸克凝聚和手征(标量)包括在有限温度$T$的同位旋破缺效应的兼容性。这些包括$m_u\neq m_d$的贡献以及电磁($e\neq 0$)的修正,都在一个一致的手征拉格朗日框架中处理的SU(2)和SU(3)手征微扰理论的领先秩序,使我们的预测是模型无关的。从$<\bar q q>= <\bar u u + \bar d d >$中提取的手性恢复温度几乎不受影响,而对于三味情形SU(3),同位旋断裂序参量$<\bar u u - \bar d d >$随$T$增长。我们推导出一个求和规则的凝聚比$<\bar q q>(e\neq 0)/<\bar q q>(e=0)$与标量磁化率差$χ(T)-χ(0)$,直接测量的晶格。这种求和规则也适用于交错格点分析中凝聚态误差的估计。保持$m_u\neq m_d$允许获得的连接和断开的贡献的磁化率,即使在同位旋极限,其温度,质量和同位旋断裂的依赖性,我们详细分析。断开的部分线性增长,在手征(红外)极限为$T/M_π$发散,而连接的部分显示二次行为,红外规则为$T^2/M_η^2$和来自$π^0η$混合条款。这种光滑的连接行为表明,在转变温度附近的同位旋破缺关联弱于临界手征关联。我们探讨了一些后果与晶格数据和它们的标度特性,我们目前的分析物理质量,即超出手征极限,提供了一个有用的模型独立的描述低和中等温度。
In this paper, we consider two-flavor QCD at zero temperature and finite isospin chemical potential ($μ_I$) using a model-independent analysis within chiral perturbation theory at next-to-leading order. We calculate the effective potential, the chiral condensate and the pion condensate in the pion-condensed phase at both zero and nonzero pionic source. We compare our finite pionic source results for the chiral condensate and the pion condensate with recent (2+1)-flavor lattice QCD results and find that they are in excellent agreement.
In this paper, we calculate the equation of state of two-flavor finite isospin chiral perturbation theory at next-to-leading order in the pion-condensed phase at zero temperature. We show that the transition from the vacuum phase to a Bose-condensed phase is of second order. While the tree-level result has been known for some time, surprisingly quantum effects have not yet been incorporated into the equation of state. We find that the corrections to the quantities we compute, namely the isospin density, pressure, and equation of state, increase with increasing isospin chemical potential. We co…
We analyze the features of strongly interacting matter in the presence of nonzero isospin chemical potential $μ_I$, within a nonlocal two-flavor Polyakov-Nambu-Jona-Lasinio (PNJL) model. For a system at finite temperature $T$, we describe the behavior of various thermodynamic quantities and study the phase diagram in the $μ_I - T$ plane. In particular, it is found that for values of $μ_I$ larger than the pion mass and temperatures lower than a critical value of about 170 MeV the system lies in an isospin symmetry broken phase signaled by the presence of a nonzero pion condensate. Our results f…
Duality between chiral symmetry breaking and charged pion condensation at large $N_c$: Consideration of an NJL$_2$ model with baryon-, isospin- and chiral isospin chemical potentials
In this paper the phase structure of the dense quark matter has been investigated in the presence of baryon $μ_B$, isospin $μ_I$, chiral $μ_{5}$ and chiral isospin $μ_{I5}$ chemical potentials in the framework of Nambu--Jona-Lasinio model. It has been shown that in the large-$N_{c}$ limit ($N_{c}$ is the number of quark colours) there exist three duality correspondences in the model. The first duality is between the chiral symmetry breaking and the charged pion condensation phenomena. And there are two new dualities that hold only for chiral symmetry breaking and charged pion condensation phen…
Influence of the isospin and hypercharge chemical potentials on the location of the CEP in the mu_B-T phase diagram of the SU(3)_L x SU(3)_R chiral quark model
We consider two-flavor chiral perturbation theory ($χ$PT) at finite isospin chemical potential $μ_I$ and finite temperature $T$. We calculate the effective potential and the quark and pion condensates as functions of $T$ and $μ_I$ to next-to-leading order in the low-energy expansion in the presence of a pionic source. We map out the phase diagram in the $μ_I$--$T$ plane. Numerically, we find that the transition to the pion-condensed phase is second order in the region of validity of $χ$PT, which is in agreement with model calculations and lattice simulations. Finally, we calculate the pressure…
In this paper the phase structure of dense quark matter has been investigated in the presence of baryon, isospin and chiral isospin chemical potentials in the framework of (3+1)-dimensional Nambu--Jona-Lasinio model with two quark flavors. It has been shown that in the large-$N_{c}$ limit ($N_{c}$ is the number of colors of quarks) there exists a duality correspondence between the chiral symmetry breaking phase and the charged pion condensation one. The key conclusion of our studies is the fact that chiral isospin chemical potential generates charged pion condensation in dense quark matter wit…
Isospin asymmetry is the well-known property of dense quark matter, which exists in the compact stars and is produced in heavy ion collisions. On the other hand, the chiral imbalance between left- and right-handed quarks is another highly anticipated phenomenon that could occur in the dense quark matter. To investigate quark matter under these conditions, we take into account baryon -- $μ_B$, isospin -- $μ_I$ and chiral isospin -- $μ_{I5}$ chemical potentials and study QCD phase portrait using NJL$_4$ model generalized to two massive quarks that could condense into the pion condensation. We ha…
We investigate two different models. In one of them massive fermions interact with a massive scalar field and in the other the fermion field is in an electrical field (QED2). The chiral condensates are calculated in one-loop approximation. We found that the chiral condensate in the case of the Yukawa interaction the fermions and scalar field does not vanish if the mass of the fermion field tends to zero. The chiral condensate disappears in QED2, if the fermion mass is zero.
A chiral soliton lattice (CSL), proposed as the ground state of rotating baryonic matter at a finite density, is shown to be unstable in a large parameter region for two flavors owing to pion condensations, leading to two types of non-Abelian (NA) CSL phases (dimer and deconfining phases). We determine the phase diagram where the dimer phase meets the other phases and QCD vacuum at three tricritical points. The critical angular velocity for NA-CSLs is lower than the $η$-CSL. Each NA soliton carries an isospin, and an antiferro-isospin chain is formed leading to gapless isospinons. The anomalou…
We use the Polyakov-loop extended two-flavor quark-meson model as a low-energy effective model for QCD to study 1) the possibility of inhomogeneous chiral condensates and its competition with a homogeneous pion condensate in the $μ$--$μ_I$ plane at $T=0$ and 2) the phase diagram in the $μ_I$--$T$ plane. In the $μ$--$μ_I$ plane, we find that an inhomogeneous chiral condensate only exists for pion masses lower that 37.1 MeV and does not coexist with a homogeneous pion condensate. In the $μ_I$--$T$ plane, we find that the phase transition to a Bose-condensed phase is of second order for all value…