Abhishek Atreya

In this paper, we extend our earlier study of the spontaneous $CP$ violating scattering of quarks and antiquarks from QCD $Z(3)$ domain walls for the situation when these walls have asymmetric profiles of the Polyakov loop order parameter $l(x)$. Dynamical quarks lead to the explicit breaking of $Z(3)$ symmetry, which lifts the degeneracy of the $Z(3)$ vacua arising from spontaneous breaking of the $Z(3)$ symmetry in the quark-gluon plasma phase. The resulting domain walls have an asymmetric profile of $l(x)$ (under the reflection $x\to -x$ for a domain wall centered at the origin). We calculate the background gauge field profile $A_0$ associated with this domain wall profile. Interestingly, even with the asymmetric $l(x)$ profile, quark-antiquark scattering from the corresponding gauge field configuration does not reflect this asymmetry. We show that the expected asymmetry in scattering arises when we include the effect of the asymmetric profile of $l(x)$ on the effective mass of quarks and antiquarks and calculate the resultant scattering. We discuss the effects of such asymmetric $Z(3)$ walls in generating quark and antiquark density fluctuations in cosmology, and in relativistic heavy-ion collisions, e.g., event-by-event baryon fluctuations. DOI: http://dx.doi.org/10.1103/PhysRevD.90.125016 © 2014 American Physical Society

In this paper we discuss the possibility of $J/\psi$ disintegration due to $Z\left(3\right)$ domain walls that are expected to form in a QGP medium. These domain walls give rise to a localized color electric field, which disintegrates $J/\psi$, on interaction, by changing its color composition and simultaneously exciting it to higher states of $c\overline{c}$ system.

We discuss a novel mechanism for segregation of baryons and antibaryons in the quark-gluon plasma phase which can lead to formation of quark and antiquark nuggets in the early universe, irrespective of the order of the quark-hadron phase transition. This happens due to $CP$ violating scattering of quarks and antiquarks from moving $Z(3)$ domain walls. $CP$ violation here is spontaneous in nature and arises from the nontrivial profile of the background gauge field ($A_0$) between different $Z(3)$ vacua. We study the effect of this spontaneous $CP$ violation on the baryon transport across the collapsing large $Z(3)$ domain walls (which can arise in the context of certain low energy scale inflationary models). Our results show that this $CP$ violation can lead to large concentrations of baryons and antibaryons in the early universe. The quark and antiquark nuggets, formed by this alternate mechanism, can provide a viable dark matter candidate within standard model without violating any observational constraints.

In this paper we discuss the possibility of $J/\psi$ disintegration due the $Z(3)$ domain walls that are expected to form in QGP medium. These domain walls give rise to localised color electric field which disintegrates $J/\psi$, on interaction, by changing the color composition and simultaneously exciting it to higher states of $c\bar{c}$ system.

In this paper, we extend our earlier study of spontaneous CP violating scattering of quarks and anti-quarks from QCD $Z\left(3\right)$ domain walls for the situation when these walls have asymmetric profiles of the Polyakov loop order parameter $l(x)$. Dynamical quarks lead to explicit breaking of $Z(3)$ symmetry, which lifts the degeneracy of the $Z(3)$ vacua arising from spontaneous breaking of the $Z(3)$ symmetry in the quark-gluon plasma (QGP) phase. Resulting domain walls have asymmetric profile of $l(x)$ (under reflection $x \rightarrow -x$ for a domain wall centered at the origin). We calculate the background gauge field profile $A_0$ associated with this domain wall profile. Interestingly, even with the asymmetric $l(x)$ profile, quark-antiquark scattering from the corresponding gauge field configuration does not reflect this asymmetry. We show that the expected asymmetry in scattering arises when we include the effect of asymmetric profile of $l(x)$ on the effective mass of quarks and antiquarks and calculate resultant scattering. We discuss the effects of such asymmetric Z(3) walls in generating quark and antiquark density fluctuations in cosmology, and in relativistic heavy-ion collisions e.g. event-by-event baryon fluctuations.

We discuss a novel mechanism for segregation of baryons and anti-baryons in the quark-gluon plasma phase which can lead to formation of quark and antiquark nuggets in the early universe, irrespective of the order of the quark-hadron phase transition. This happens due to CP violating scattering of quarks and antiquarks from moving $Z(3)$ domain walls. CP violation here is spontaneous in nature and arises from the nontrivial profile of the background gauge field ($A_{0}$ ) between different $Z(3)$ vacua. We study the effect of this spontaneous CP violation on the baryon transport across the collapsing large $Z(3)$ domain walls (which can arise in the context of certain low energy scale inflationary models). Our results show that this CP violation can lead to large concentrations of baryons and anti-baryons in the early universe. The quark and antiquark nuggets, formed by this alternate mechanism, can provide a viable dark matter candidate within standard model without violating any observational constraints.

In this paper, we explore the possibility of spontaneous CP violation in the scattering of quarks and anti-quarks from QCD Z(3) domain walls. The CP violation here arises from the nontrivial profile of the background gauge field $(A_{0})$ between different Z(3) vacua. We calculate the spatial variation of $A_{0}$ across the Z(3) interface from the profile of the Polyakov loop $L(\vec{x})$ for the Z(3) interface and calculate the reflection of quarks and antiquarks using the Dirac equation. This spontaneous CP violation has interesting consequences for the relativistic heavy-ion collision experiments, such as baryon enhancement at high $P_{T}$. It also acts as a source of additional J/$\psi$ suppression. We also discuss its implications for the early universe.

In this paper, we explore the possibility of spontaneous $CP$ violation in the scattering of quarks and antiquarks from QCD $Z(3)$ domain walls. The $CP$ violation here arises from the nontrivial profile of the background gauge field $(A_0)$ between different $Z(3)$ vacua. We calculate the spatial variation of $A_0$ across the Z(3) interface from the profile of the Polyakov loop $L(\overrightarrow{x})$ for the Z(3) interface and calculate the reflection of quarks and antiquarks using the Dirac equation. This spontaneous $CP$ violation has interesting consequences for the relativistic heavy-ion collision experiments, such as baryon enhancement at high $P_T$. It also acts as a source of additional $J/\psi$ suppression. We also discuss its implications for the early Universe. DOI: http://dx.doi.org/10.1103/PhysRevD.85.014009 © 2012 American Physical Society