arXiv subjects

Sourav Kundu

Publications and source records attributed to Sourav Kundu.

14 recordsLinked to original sources

arXiv2026

Canonical statistical hadronization with local baryon conservation for higher-order cumulants

We study higher-order cumulants of the conserved baryon number at the LHC within the canonical ensemble with local baryon conservation. We generalize the density correlations approach of [Phys. Rev. C 110, L061902 (2024)] to incorporate the effect of Gaussian local conservation in spatial rapidity space in cumulants up to 6th order. Gaussian local conservation improves upon the commonly employed $V_c$ approach, yielding comparable predictions at midrapidity, but marked differences for larger rapidity acceptances. Our coordinate-space results are in exact agreement with the diffusion master equation approach for all cumulant ratios up to $κ_6/κ_2$. Using the blast-wave model to apply kinematic cuts, we obtain predictions for net-proton cumulants in O--O and Pb--Pb collisions at the LHC that establish an ideal hadron gas baseline. We find that local baryon conservation alone can drive $κ_6/κ_2$ to small or even negative values in restricted acceptance, a behavior often associated with chiral criticality. The conservation baseline must therefore be carefully accounted for when interpreting upcoming LHC measurements.

hep-ph↗

arXiv2026

Light-Flavour Resonance Production in High-Energy Heavy-Ion Collisions: An Experimental Review

Resonances provide sensitivity to the late-stage dynamics of heavy-ion collisions, as their lifetimes are comparable to the duration of the hadronic phase. This review summarizes state-of-the-art measurements of light-flavour mesonic and baryonic resonances, including $ρ$(770), $K^{\star}$(892), $ϕ$(1020), $Δ$(1232), $Λ^{\star}$(1520), $Σ^{\star}$(1385) and $Ξ^\star$(1530), in pp, p-A and A-A collisions at SPS, RHIC and the LHC. Systematic trends in yields, mass and width modifications, transverse-momentum spectra, nuclear modification factors, and particle ratios reveal the interplay of re-scattering and regeneration, medium-induced suppression, and the development of collective dynamics with increasing system size and multiplicity. Anisotropic flow results confirm the coupling of resonances to the expanding medium, while recent vector-meson spin-alignment measurements offer fresh insights into hadronization mechanisms and local fields. Ultra-peripheral collisions provide vacuum-like baselines for isolating in-medium effects. Emerging opportunities for charm-resonance studies in upcoming high-luminosity experiments are also outlined.Together, these advances demonstrate the important role of resonance measurements in constraining the space-time evolution of strongly interacting matter.

nucl-ex↗

arXiv2024

Backbone Mediated Electrical Transport in a Double-Stranded DNA

In the field of DNA nanotechnology, it is common wisdom that charge transport occurs through the π stacked bases of double-stranded DNA. However, recent experimental findings by Zhuravel et. al. [Nat. Nanotech. 15, 836 (2020)] suggest that electronic transport happens through the backbone channels instead of π-π interaction of the nitrogen bases. These new experimental insights call for a detail investigation. In keeping with this, we examine charge transport properties of three characteristic double-stranded DNA sequences (periodic GC, periodic AT and random ATGC sequences) within a tight-binding framework where backbones form the main conduction channels. Using techniques based on the Green function method, we inspect the single-particle density of states and localization properties of DNA in the presence of discontinuities (nicks) along the backbone channels. We also investigate the effect of these nicks on current-voltage response using the Landauer - Buttiker formalism for a two-terminal geometry where the source electrode is attached to one backbone strand and the drain to the other. We observe that the periodic DNA sequence of GC bases is metallic in nature, while the periodic AT sequence and the random ATGC sequence are insulating. Further, the effects of nicks on the transport properties of the periodic GC sequence is interesting: while a single nick on the upper backbone does not affect electronic transport, the addition of a second nick on the lower backbone causes the current to vanish altogether. This is found to be robust against changes in the positions of the nicks, as well as the alternation of the source and drain electrodes.

cond-mat.mes-hall↗

arXiv2024

Determining the purity of single-helical proteins from electronic specific heat measurements

We present a theoretical investigation of the electronic specific heat (ESH) at constant volume (Cv) of single-helical proteins modeled within the tight-binding (TB) framework. We study the effects of helical symmetry, long-range hopping, environment and biological defects on thermal properties. We employ a general TB model to incorporate all parameters relevant to the helical structure of the protein. In order to provide additional insights into our results for the ESH, we also study the electronic density of states for various disorder strengths. We observe that the variation of the specific heat with disorder is very different in low and high temperature regimes, though the variation of ESH with temperature possesses a universal pattern upon varying disorder strengths related to environmental effects. Lastly, we propose an interesting application of the ESH spectra of proteins. We show that by studying the ESH of single-helical proteins, one can distinguish a defective sample from a pure one. This observation can serve as the basis of a screening technique that can be applied prior to a whole genome testing, thereby saving valuable time & resources.

cond-mat.mes-hall↗

arXiv2023

Majorana qubit codes that also correct odd-weight errors

The tetron architecture is a promising candidate for topological quantum computation. Each tetron Majorana island has four Majorana zero modes, and possible measurements are constrained to span zero or two Majoranas per tetron. Such measurements are known to be sufficient for correcting so-called "bosonic errors," which affect an even number of Majoranas per tetron. We demonstrate that such measurements are also sufficient for correcting "fermionic errors," which affect an odd number of Majoranas per tetron. In contrast, previous proposals for "fermionic error correction" on tetrons introduce more experimental challenges. We show that "fermionic codes" can be derived from traditional "bosonic codes" by inclusion of tetrons in the stabilizer group.

quant-ph↗

arXiv2022

Graphene nanopore devices for DNA sequencing: A tight-binding model study

We present a tight-binding model study of a two-terminal graphene nanopore device for sequential determination of DNA bases. Using Green's function technique we investigate the changes in electronic transport properties of the device due to insertion of different nucleotides into the nanopore created within a zigzag graphene nanoribbon. First we try to characterise the device in static condition and then go for sequencing application by setting the bias across it to a specific voltage and then recording the characteristic current signals corresponding to each nucleotides of a translocating DNA. Our investigations show that graphene nanopores can certainly become very efficient and reliable for sequencing applications in future.

cond-mat.mes-hall↗

arXiv2021

Spin alignment measurement of vector mesons produced in high energy collisions

This review covers the recent experimental development on spin alignment measurements of $K^{*0}$ and $ϕ$ vector mesons in heavy-ion and pp collisions at RHIC and LHC energies. Measurements in $e^+e^-$ collisions at LEP energies are also discussed. Spin alignment of vector mesons are studied by measuring the second diagonal element $ρ_{00}$ of spin density matrix. The $ρ_{00}$ is obtained by measuring the angular distribution of vector meson decay daughter with respect to the quantization axis in vector meson rest frame. Measured $ρ_{00}$ values for vector mesons are found to be larger than 1/3 at high momentum in $e^+e^-$ collisions at LEP energies, suggesting the preferential production of vector meson with helicity zero state from the fragmentation process. The $ρ_{00}$ values are found to be smaller than 1/3 ($ρ_{00}$ = 1/3 implies no spin alignment) for $K^{*0}$ and $ϕ$ vector mesons at low transverse momentum in Pb--Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV. This observations are qualitatively consistent with the expectation from models which attribute the spin alignment effect due to polarization of quarks in the presence of large initial angular momentum in non-central heavy-ion collisions and its subsequent hadronization by the process of recombination. No significant spin alignment effect is observed for $K^0_S$ (spin = 0) in mid-central Pb--Pb collisions and for vector mesons in pp collisions. However, the preliminary results of $ρ_{00}$ for $ϕ$ mesons are larger than 1/3 at intermediate $p_{\mathrm{T}}$ in Au--Au collisions at RHIC energies and can be attributed to the presence of $ϕ$ meson field. Although there is evidence of spin alignment effect of vector mesons in heavy-ion collisions but the measured effect is surprisingly larger in context of hyperon polarization. Therefore these results will trigger further theoretical study.

nucl-ex↗

arXiv2019

Effect of color reconnection on forward-backward multiplicity and mean transverse momentum correlation

Color reconnection (CR) mechanism in PYTHIA model has been reported to be essential to describe the flow-like collective effect observed in high multiplicity $p$+$p$ and $p$+Pb collisions. In this work, we test this mechanism towards explaining the Forward-Backward multiplicity correlation (b$_{\mathrm {cor}}$) measurements in $p$+$p$ collisions at the LHC energies. Out of the three different CR schemes implemented in PYTHIA, (a) MPI based CR (default mechanism), (b) QCD based CR and (c) Gluon moved CR, we found that the QCD based CR scheme describes relatively better the ALICE measurements of b$_{\mathrm {cor}}$ in $p$+$p$ collisions at $\sqrt{\mathrm s}$ = 0.9 and 7 TeV. In addition, we have tuned the parameters of the default CR mechanism in PYTHIA to describe simultaneously the measured charged particle multiplicity pseudo-rapidity ($η$) distribution and b$_{\mathrm {cor}}$. We found that an average number of multipartonic interactions ($\langle N_{\mathrm {MPI}} \rangle$) between 2.5 to 3 and CR range between 0.9 to 2.5 best describes the experimental data. Finally, we have presented a study using PYTHIA events for $p$+$p$ collisions at $\sqrt{\mathrm s}$ = 7 TeV which shows that the strength of Forward-Backward mean transverse momentum correlation (b$^{\langle p_{\mathrm{T}}\rangle \langle p_{\mathrm{T}} \rangle}_{\rm {cor}}$) is found to increase with CR in contrast to decrease of b$_{\rm {cor}}$ values with CR effect. Hence, simultaneously studying the b$^{\langle p_{\mathrm{T}}\rangle \langle p_{\mathrm{T}} \rangle}_{\rm {cor}}$ and b$_{\mathrm {\rm {cor}}}$ in the experiments will help in establishing the arguments either in favour or in disfavour of CR effect in the measurements.

hep-ph↗

arXiv2018

Study of charged particle multiplicity, average transverse momentum and azimuthal anisotropy in Xe+Xe collisions at $\sqrt{s_{NN}}$ = 5.44 TeV using AMPT model

We have studied the average charged particle density ($<$dN$_{ch}$/d$η$$>$), transverse momentum ($p_{\mathrm{T}}$) spectra, $<$$p_{\mathrm{T}}$$>$ and azimuthal anisotropies of inclusive charged particles produced in Xe+Xe collisions at $\sqrt{s_{NN}}$ = 5.44 TeV using A Multiphase Transport Model (AMPT), which includes the deformation of Xe$^{129}$ nucleus. Calculations have been performed with the string melting version of AMPT model and compared with the recent measurements from the ALICE experiment. The model results over predict the measured $<$dN$_{ch}$/d$η$$>$ for central collisions, agree with the data for mid-central collisions and under predict the measurements for peripheral collisions. The centrality dependence of $<$$p_{\mathrm{T}}$$>$ of charged particles measured in ALICE is not reproduced by the model results. The calculated elliptic flow ($v_{2}$) from AMPT model overpredicts the ALICE measurements in central collisions but are consistent with the data in mid central collisions. We find that the model shows a mild centrality dependence of triangular flow and overestimates the ALICE measurements. Within the model framework, we have also studied various collision configurations of Xe nuclei such as body-body, tip-tip, side-side and random. We find a strong dependence of the above observable on the collision configurations.

nucl-ex↗

arXiv2016

Electronic transport in single-helical protein molecules: Effects of multiple charge conduction pathways and helical symmetry

We propose a tight-binding model to investigate electronic transport properties of single helical protein molecules incorporating both the helical symmetry and the possibility of multiple charge transfer pathways. Our study reveals that due to existence of both the multiple charge transfer pathways and helical symmetry, the transport properties are quite rigid under influence of envi- ronmental fluctuations which indicates that these biomolecules can serve as better alternatives in nanoelectronic devices than its other biological counterparts e.g., single-stranded DNA.

cond-mat.mes-hall↗

arXiv2016

Detection of basepair mismatches in DNA using graphene based nanopore device

We present an unique way to detect basepair mismatches in DNA leading to different epigenetic disorder by the method of nanopore sequencing. Based on a tight-binding formulation of graphene nanopore based device, using Greens function approach we measure the changes in the electronic transport properties of the device as we translocate a double-stranded DNA through the nanopore embeded in a zigzag graphene nanoribbon. In the present work we not only successfully detect the usual AT and GC pairs, but also a set of possible mismatches in the complementary base-pairing without any ambiguity. Our investigation shows that this device can also be used for reliable sequential detection of other biomolecules.

cond-mat.mes-hall↗

arXiv2015

Localization phenomena in a DNA double helix structure : A twisted ladder model

In this work we propose a model for DNA double helix within the tight-binding framework that incorporates the helicity of the molecules. We have studied localization properties of three DNAsequences,the periodic poly(dG)-poly(dC) and poly(dA)-poly(dT) sequences and the random ATGCsequence, all of which are coupled to backbone withrandom site energies representing the environmentalfluctuations. We observe that due to helicity of DNA, electron transport is greatly enhancedand there exists almost a disorder-strength independent critical value of the hopping integral, thataccounts for helicity of DNA, for which the electronic states become maximally extended. We havealso investigated the effect of backbone energetics on the transmission and I-V characteristics of DNA.

cond-mat.mes-hall↗

arXiv2015

Electronic Specific Heat of DNA: Effects of backbones and disorder

In this present work we report the results of our investigation on the electronic specific heat (ESH) of DNA molecule modelled within the tight-binding framework. We take four different DNA sequences ranging from periodic, quasi-periodic to random and studied both ESH and also the density of states to supplement our ESH results. The role of the backbone structure and the effectsof environment on ESH are discussed. We observe that irrespective of the sequences there is auniversal response of the ESH spectra for a given disorder. The nature of response of specific heaton backbone disorder is totally opposite in low and high temperature regimes.

cond-mat.mes-hall↗

arXiv2015

Conformation dependent electronic transport in a DNA double-helix

In this work we report the study of conformation dependent electronic transport properties of DNA double-helix within tight-binding framework including its helical symmetry. We have studied the changes in localization properties of DNA as we alter the number of stacked bases within a pitch of the double-helix keeping the total number of nucleotides in the DNA chain fixed. We take three DNA sequences, two of them are periodic and one is random and observe that localization length increases as we increase the radius of DNA double-helix i.e., number of nucleotides within a pitch. We have also investigated the effect of backbone energetic on the I-V response of the system and we find that in presence of helical symmetry, depending on the interplay of conformal variation and disorder strength DNA can be found in either metallic or semiconducting and even in an insulating phase, which in turn successfully explain all the experimental findings by a single model.

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