mujeeb hasan | Aligarh Muslim University (original) (raw)

Papers by mujeeb hasan

We have investigated how a strong magnetic field (B) could decipher the anisotropic interaction i... more We have investigated how a strong magnetic field (B) could decipher the anisotropic interaction in heavy quark (Q) and antiquark (Q̅) bound states through the perturbative thermal QCD in real-time formalism. So we thermalize Schwinger propagator for quarks in LLL and the Feynman propagator for gluons to calculate the gluon self-energy. For the quark-loop contribution to the self-energy, the medium does not have any temperature correction and the vacuum term gives rise an anisotropic term whereas the gluon-loop yields temperature correction. This finding in quark-loop contribution corroborates the equivalence of a massless QED in (1+1)-dimension with the massless thermal QCD in strong B, which (quark sector) is reduced to (1+1)-dimension (longitudinal). Thus the permittivity of the medium behaves like as a tensor. Thus the permittivity of medium makes the Q Q̅ potential anisotropic, which resembles with a contemporary results found in lattice studies. As a result, potential for Q Q̅-...

We examined the effects of the weak magnetic field on the dissociation of heavy quarkonia immerse... more We examined the effects of the weak magnetic field on the dissociation of heavy quarkonia immersed in a thermal medium of quarks and gluons. For that purpose, we have revisited the general structure of gluon self-energy tensor in the presence of a weak magnetic field in thermal medium and obtained the relevant structure functions. The structure functions give the real and imaginary parts of the resummed gluon propagator, which further give the respective dielectric permittivities. The real and imaginary parts of the dielectric permittivity will be used to evaluate the real and imaginary parts of the complex heavy quark potential. The real-part of the potential is found to be more screened, whereas the magnitude of the imaginary-part of the potential gets increased on increasing the value of both temperature and magnetic field. In addition to this, we have observed that the real-part gets slightly more screened while the imaginary part gets increased in the presence of a weak magneti...

arXiv: High Energy Physics - Phenomenology, 2020

We have investigated how a strong magnetic field (B) could decipher the anisotropic interaction i... more We have investigated how a strong magnetic field (B) could decipher the anisotropic interaction in heavy quark ($Q$) and antiquark ($\bar Q$) bound states through the perturbative thermal QCD in real-time formalism. So we thermalize Schwinger propagator for quarks in LLL and the Feynman propagator for gluons to calculate the gluon self-energy. For the quark-loop contribution to the self-energy, the medium does not have any temperature correction and the vacuum term gives rise an anisotropic term whereas the gluon-loop yields temperature correction. This finding in quark-loop contribution corroborates the equivalence of a massless QED in (1+1)-dimension with the massless thermal QCD in strong B, which (quark sector) is reduced to (1+1)-dimension (longitudinal). Thus the permittivity of the medium behaves like as a tensor. Thus the permittivity of medium makes the QbarQQ \bar QQbarQ potential anisotropic, which resembles with a contemporary results found in lattice studies. As a result, poten...

arXiv: High Energy Physics - Phenomenology, 2019

We have investigated how the wakes in the induced charge density and in the potential due to the ... more We have investigated how the wakes in the induced charge density and in the potential due to the passage of highly energetic partons through a thermal QCD medium get affected by the presence of strong magnetic field. For that purpose, we wish to analyze first the dielectric responses of the medium both in presence and absence of strong magnetic field. Therefore, we have revisited the general form for the gluon self-energy tensor at finite temperature and finite magnetic field and then calculate the relevant structure functions at finite temperature and SMF limit. We found that for slow moving partons, the real part of dielectric function is not affected by the magnetic field whereas for fast moving partons, for small k, it becomes very large and approaches towards its counterpart at B = 0, for large k. On the other hand the imaginary part is decreased for both slow and fast moving partons. With these ingredients, we found that the oscillation in the induced charge density, due to th...

International Journal of Modern Physics A, 2021

We have investigated how the wakes in the induced charge density and in the potential due to the ... more We have investigated how the wakes in the induced charge density and in the potential due to the passage of highly energetic partons through a thermal QCD medium get affected by the presence of strong magnetic field. For that purpose, we wish to analyze first the dielectric responses of the medium both in presence and absence of strong magnetic field. We found that for slow moving partons, the real part of dielectric function is not affected by the magnetic field whereas for fast moving partons, for small ∣textbfk∣|\textbf{k}|∣textbfk∣, it becomes very large and approaches towards its counterpart at B=0B=0B=0, for large ∣textbfk∣|\textbf{k}|∣textbfk∣. On the other hand the imaginary part is decreased for both slow and fast moving partons, due to the fact that the imaginary contribution due to quark-loop vanishes. With these ingredients, we found that the oscillation in the (scaled) induced charge density, due to the very fast partons becomes less pronounced in the presence of strong magnetic field whereas for smaller ...

Recently there is a resurrection in the study of heavy quark bound states in a hot and baryonless... more Recently there is a resurrection in the study of heavy quark bound states in a hot and baryonless matter with an ambient magnetic field but the matter produced at heavy-ion collider experiments is not perfectly baryonless, so we wish to explore the effect of small baryon asymmetry on the properties of heavy quarkonia immersed in a strongly magnetized hot quark matter. Therefore, we have first revisited the structure of gluon self-energy tensor in the above environment to compute the resummed propagator for gluons. This resummed propagator embodies the properties of medium, which gets translated into the (complex) potential between Q and Q̄ placed in the medium. We observe that the baryon asymmetry makes the real-part of potential slightly more attractive and weakens the imaginary-part. This opposing effects thus lead to the enhancement of binding energies and the reduction of thermal widths of QQ̄ ground states, respectively. Finally, the properties of quarkonia thus deciphered faci...

Recent analysis suggests that a strong magnetic field is expected to be produced at very early st... more Recent analysis suggests that a strong magnetic field is expected to be produced at very early stage of ultrarelativistic heavy ion collisions (URHIC), when the event is off-central. Heavy quark pairs (QQ̄) are also produced at the nascent stages of URHICs when the magnetic field is expected to be very strong. For example, charm-anti charm pairs are produced at a typical time of tcc̄(≃ 1/2mc) ≃ 0.1 fm whereas the magnetic field is expected to be very strong typically up to tB ≃ 0.2 fm. Thus the coincidence of production time scales motivates us to investigate the properties of heavy quarkonia in the presence of strong magnetic field. For this purpose we have first calculated the gluon self-energy for a thermal QCD up to one-loop in a strong magnetic field in real-time formalism to calculate the effective gluon propagator, which in the static limit gives the dielectric permittivity, ε(k) embodying the effects of strong magnetic field on thermal (QCD) medium. Finally the inverse Fouri...

The European Physical Journal C, Nov 1, 2017

We have investigated the properties of quarkonia in a thermal QCD medium in the background of str... more We have investigated the properties of quarkonia in a thermal QCD medium in the background of strong magnetic field. For that purpose, we employ the Schwinger proper-time quark propagator in the lowest Landau level to calculate the one-loop gluon self-energy, which in the sequel gives the effective gluon propagator. As an artifact of strong magnetic field approximation (eB >> T 2 and eB >> m 2), the Debye mass for massless flavors is found to depend only on the magnetic field which is the dominant scale in comparison to the scales prevalent in the thermal medium. However, for physical quark masses, it depends on both magnetic field and temperature in a low temperature and high magnetic field but the temperature dependence is very meager and becomes independent of the temperature beyond a certain temperature and magnetic field. With the above mentioned ingredients, the potential between heavy quark (Q) and anti-quark (Q) is obtained in a hot QCD medium in the presence of a strong magnetic field by correcting both short-and longrange components of the potential in the real-time formalism. It is found that the long-range part of the quarkonium potential is affected much more by magnetic field as compared to the short-range part. This observation facilitates us to estimate the magnetic field beyond which the potential will be too weak to bind QQ together. For example, the J/ψ is dissociated at eB ∼ 10 m 2 π and ϒ is dissociated at eB ∼ 100 m 2 π whereas its excited states, ψ and ϒ are dissociated at smaller magnetic field eB = m 2 π , 13m 2 π , respectively.

Nuclear Physics A

In this article we have investigated the effects of strong magnetic field on the properties of qu... more In this article we have investigated the effects of strong magnetic field on the properties of quarkonia immersed in a thermal medium of quarks and gluons and studied its quasi-free dissociation due to the Landau-damping. Thermalizing the Schwinger propagator in the lowest Landau levels for quarks and the Feynman propagator for gluons in real-time formalism, we have calculated the resummed retarded and symmetric propagators, which in turn give the real and imaginary components of dielectric permittivity, respectively. Thus the effect of a strongly magnetized hot QCD medium have been encrypted into the real and imaginary parts of heavy quark interaction in medium, respectively. The magnetic field affects the large-distance interaction more than the short-distance interaction, as a result, the real part of potential becomes more attractive and the magnitude of imaginary part too becomes larger, compared to the thermal medium in absence of strong magnetic field. As a consequence the average size of J/ψ's and ψ ′ 's are increased but χ c 's get shrunk. Similarly the magnetic field affects the binding of J/ψ's and χ c 's discriminately, i.e. it decreases the binding of J/ψ and increases for χ c. However, the further increase in magnetic field results in the decrease of binding energies. On contrary the magnetic field increases the width of the resonances, unless the temperature is sufficiently high. We have finally studied how the presence of magnetic field affects the dissolution of quarkonia in a thermal medium due to the Landau damping, where the dissociation temperatures are found to increase compared to the thermal medium in absence of magnetic field. However, further increase of magnetic field decreases the dissociation temperatures. For example, J/ψ's and χ c 's are dissociated at higher

Physical Review D, 2020

We examined the effects of the weak magnetic field on the properties of heavy quarkonia immersed ... more We examined the effects of the weak magnetic field on the properties of heavy quarkonia immersed in a thermal medium of quarks and gluons and studied how the magnetic field affects the quasifree dissociation of quarkonia in the aforementioned medium. For that purpose, we have revisited the general structure of gluon self-energy tensor in the presence of a weak magnetic field in thermal medium and obtained the relevant structure functions using the imaginary-time formalism. The structure functions give rise to the real and imaginary parts of the resummed gluon propagator, which further give the real and imaginary parts of the dielectric permittivity. The real and imaginary parts of the dielectric permittivity will be used to evaluate the real and imaginary parts of the complex heavy quark potential. We have observed that the real part of the potential is found to be more screened, whereas the magnitude of the imaginary part of the potential gets increased on increasing the value of b...

We have investigated how a strong magnetic field (B) could decipher the anisotropic interaction i... more We have investigated how a strong magnetic field (B) could decipher the anisotropic interaction in heavy quark (Q) and antiquark (Q̅) bound states through the perturbative thermal QCD in real-time formalism. So we thermalize Schwinger propagator for quarks in LLL and the Feynman propagator for gluons to calculate the gluon self-energy. For the quark-loop contribution to the self-energy, the medium does not have any temperature correction and the vacuum term gives rise an anisotropic term whereas the gluon-loop yields temperature correction. This finding in quark-loop contribution corroborates the equivalence of a massless QED in (1+1)-dimension with the massless thermal QCD in strong B, which (quark sector) is reduced to (1+1)-dimension (longitudinal). Thus the permittivity of the medium behaves like as a tensor. Thus the permittivity of medium makes the Q Q̅ potential anisotropic, which resembles with a contemporary results found in lattice studies. As a result, potential for Q Q̅-...

We examined the effects of the weak magnetic field on the dissociation of heavy quarkonia immerse... more We examined the effects of the weak magnetic field on the dissociation of heavy quarkonia immersed in a thermal medium of quarks and gluons. For that purpose, we have revisited the general structure of gluon self-energy tensor in the presence of a weak magnetic field in thermal medium and obtained the relevant structure functions. The structure functions give the real and imaginary parts of the resummed gluon propagator, which further give the respective dielectric permittivities. The real and imaginary parts of the dielectric permittivity will be used to evaluate the real and imaginary parts of the complex heavy quark potential. The real-part of the potential is found to be more screened, whereas the magnitude of the imaginary-part of the potential gets increased on increasing the value of both temperature and magnetic field. In addition to this, we have observed that the real-part gets slightly more screened while the imaginary part gets increased in the presence of a weak magneti...

arXiv: High Energy Physics - Phenomenology, 2020

We have investigated how a strong magnetic field (B) could decipher the anisotropic interaction i... more We have investigated how a strong magnetic field (B) could decipher the anisotropic interaction in heavy quark ($Q$) and antiquark ($\bar Q$) bound states through the perturbative thermal QCD in real-time formalism. So we thermalize Schwinger propagator for quarks in LLL and the Feynman propagator for gluons to calculate the gluon self-energy. For the quark-loop contribution to the self-energy, the medium does not have any temperature correction and the vacuum term gives rise an anisotropic term whereas the gluon-loop yields temperature correction. This finding in quark-loop contribution corroborates the equivalence of a massless QED in (1+1)-dimension with the massless thermal QCD in strong B, which (quark sector) is reduced to (1+1)-dimension (longitudinal). Thus the permittivity of the medium behaves like as a tensor. Thus the permittivity of medium makes the QbarQQ \bar QQbarQ potential anisotropic, which resembles with a contemporary results found in lattice studies. As a result, poten...

arXiv: High Energy Physics - Phenomenology, 2019

We have investigated how the wakes in the induced charge density and in the potential due to the ... more We have investigated how the wakes in the induced charge density and in the potential due to the passage of highly energetic partons through a thermal QCD medium get affected by the presence of strong magnetic field. For that purpose, we wish to analyze first the dielectric responses of the medium both in presence and absence of strong magnetic field. Therefore, we have revisited the general form for the gluon self-energy tensor at finite temperature and finite magnetic field and then calculate the relevant structure functions at finite temperature and SMF limit. We found that for slow moving partons, the real part of dielectric function is not affected by the magnetic field whereas for fast moving partons, for small k, it becomes very large and approaches towards its counterpart at B = 0, for large k. On the other hand the imaginary part is decreased for both slow and fast moving partons. With these ingredients, we found that the oscillation in the induced charge density, due to th...

International Journal of Modern Physics A, 2021

We have investigated how the wakes in the induced charge density and in the potential due to the ... more We have investigated how the wakes in the induced charge density and in the potential due to the passage of highly energetic partons through a thermal QCD medium get affected by the presence of strong magnetic field. For that purpose, we wish to analyze first the dielectric responses of the medium both in presence and absence of strong magnetic field. We found that for slow moving partons, the real part of dielectric function is not affected by the magnetic field whereas for fast moving partons, for small ∣textbfk∣|\textbf{k}|∣textbfk∣, it becomes very large and approaches towards its counterpart at B=0B=0B=0, for large ∣textbfk∣|\textbf{k}|∣textbfk∣. On the other hand the imaginary part is decreased for both slow and fast moving partons, due to the fact that the imaginary contribution due to quark-loop vanishes. With these ingredients, we found that the oscillation in the (scaled) induced charge density, due to the very fast partons becomes less pronounced in the presence of strong magnetic field whereas for smaller ...

Recently there is a resurrection in the study of heavy quark bound states in a hot and baryonless... more Recently there is a resurrection in the study of heavy quark bound states in a hot and baryonless matter with an ambient magnetic field but the matter produced at heavy-ion collider experiments is not perfectly baryonless, so we wish to explore the effect of small baryon asymmetry on the properties of heavy quarkonia immersed in a strongly magnetized hot quark matter. Therefore, we have first revisited the structure of gluon self-energy tensor in the above environment to compute the resummed propagator for gluons. This resummed propagator embodies the properties of medium, which gets translated into the (complex) potential between Q and Q̄ placed in the medium. We observe that the baryon asymmetry makes the real-part of potential slightly more attractive and weakens the imaginary-part. This opposing effects thus lead to the enhancement of binding energies and the reduction of thermal widths of QQ̄ ground states, respectively. Finally, the properties of quarkonia thus deciphered faci...

Recent analysis suggests that a strong magnetic field is expected to be produced at very early st... more Recent analysis suggests that a strong magnetic field is expected to be produced at very early stage of ultrarelativistic heavy ion collisions (URHIC), when the event is off-central. Heavy quark pairs (QQ̄) are also produced at the nascent stages of URHICs when the magnetic field is expected to be very strong. For example, charm-anti charm pairs are produced at a typical time of tcc̄(≃ 1/2mc) ≃ 0.1 fm whereas the magnetic field is expected to be very strong typically up to tB ≃ 0.2 fm. Thus the coincidence of production time scales motivates us to investigate the properties of heavy quarkonia in the presence of strong magnetic field. For this purpose we have first calculated the gluon self-energy for a thermal QCD up to one-loop in a strong magnetic field in real-time formalism to calculate the effective gluon propagator, which in the static limit gives the dielectric permittivity, ε(k) embodying the effects of strong magnetic field on thermal (QCD) medium. Finally the inverse Fouri...

The European Physical Journal C, Nov 1, 2017

We have investigated the properties of quarkonia in a thermal QCD medium in the background of str... more We have investigated the properties of quarkonia in a thermal QCD medium in the background of strong magnetic field. For that purpose, we employ the Schwinger proper-time quark propagator in the lowest Landau level to calculate the one-loop gluon self-energy, which in the sequel gives the effective gluon propagator. As an artifact of strong magnetic field approximation (eB >> T 2 and eB >> m 2), the Debye mass for massless flavors is found to depend only on the magnetic field which is the dominant scale in comparison to the scales prevalent in the thermal medium. However, for physical quark masses, it depends on both magnetic field and temperature in a low temperature and high magnetic field but the temperature dependence is very meager and becomes independent of the temperature beyond a certain temperature and magnetic field. With the above mentioned ingredients, the potential between heavy quark (Q) and anti-quark (Q) is obtained in a hot QCD medium in the presence of a strong magnetic field by correcting both short-and longrange components of the potential in the real-time formalism. It is found that the long-range part of the quarkonium potential is affected much more by magnetic field as compared to the short-range part. This observation facilitates us to estimate the magnetic field beyond which the potential will be too weak to bind QQ together. For example, the J/ψ is dissociated at eB ∼ 10 m 2 π and ϒ is dissociated at eB ∼ 100 m 2 π whereas its excited states, ψ and ϒ are dissociated at smaller magnetic field eB = m 2 π , 13m 2 π , respectively.

Nuclear Physics A

In this article we have investigated the effects of strong magnetic field on the properties of qu... more In this article we have investigated the effects of strong magnetic field on the properties of quarkonia immersed in a thermal medium of quarks and gluons and studied its quasi-free dissociation due to the Landau-damping. Thermalizing the Schwinger propagator in the lowest Landau levels for quarks and the Feynman propagator for gluons in real-time formalism, we have calculated the resummed retarded and symmetric propagators, which in turn give the real and imaginary components of dielectric permittivity, respectively. Thus the effect of a strongly magnetized hot QCD medium have been encrypted into the real and imaginary parts of heavy quark interaction in medium, respectively. The magnetic field affects the large-distance interaction more than the short-distance interaction, as a result, the real part of potential becomes more attractive and the magnitude of imaginary part too becomes larger, compared to the thermal medium in absence of strong magnetic field. As a consequence the average size of J/ψ's and ψ ′ 's are increased but χ c 's get shrunk. Similarly the magnetic field affects the binding of J/ψ's and χ c 's discriminately, i.e. it decreases the binding of J/ψ and increases for χ c. However, the further increase in magnetic field results in the decrease of binding energies. On contrary the magnetic field increases the width of the resonances, unless the temperature is sufficiently high. We have finally studied how the presence of magnetic field affects the dissolution of quarkonia in a thermal medium due to the Landau damping, where the dissociation temperatures are found to increase compared to the thermal medium in absence of magnetic field. However, further increase of magnetic field decreases the dissociation temperatures. For example, J/ψ's and χ c 's are dissociated at higher

Physical Review D, 2020

We examined the effects of the weak magnetic field on the properties of heavy quarkonia immersed ... more We examined the effects of the weak magnetic field on the properties of heavy quarkonia immersed in a thermal medium of quarks and gluons and studied how the magnetic field affects the quasifree dissociation of quarkonia in the aforementioned medium. For that purpose, we have revisited the general structure of gluon self-energy tensor in the presence of a weak magnetic field in thermal medium and obtained the relevant structure functions using the imaginary-time formalism. The structure functions give rise to the real and imaginary parts of the resummed gluon propagator, which further give the real and imaginary parts of the dielectric permittivity. The real and imaginary parts of the dielectric permittivity will be used to evaluate the real and imaginary parts of the complex heavy quark potential. We have observed that the real part of the potential is found to be more screened, whereas the magnitude of the imaginary part of the potential gets increased on increasing the value of b...