Shakeel Ahmad

Southampton Solent University | SSU · School of Media Arts and Technology

A bstract The production cross sections of D ⁰ , D ⁺ , and $$ {\Lambda}_{\textrm{c}}^{+} $$ Λ c + hadrons originating from beauty-hadron decays (i.e. non-prompt) were measured for the first time at midrapidity in proton–lead (p–Pb) collisions at the center-of-mass energy per nucleon pair of $$ \sqrt{s_{\textrm{NN}}} $$ s NN = 5 . 02 TeV. Nuclear mo...

The first measurement of the multiplicity dependence of intra-jet properties of leading charged-particle jets in proton–proton (pp) collisions is reported. The mean charged-particle multiplicity and jet fragmentation distributions are measured in minimum-bias and high-multiplicity pp collisions at center-of-mass energy $$\sqrt{s}$$ s = 13 TeV using...

A bstract The p T -differential production cross sections of non-prompt D ⁰ , D ⁺ , and $$ {\textrm{D}}_{\textrm{s}}^{+} $$ D s + mesons originating from beauty-hadron decays are measured in proton–proton collisions at a centre-of-mass energy $$ \sqrt{s} $$ s = 13 TeV. The measurements are performed at midrapidity, | y | < 0 . 5, with the data samp...

Deuterons are atomic nuclei composed of a neutron and a proton held together by the strong interaction. Unbound ensembles composed of a deuteron and a third nucleon have been investigated in the past using scattering experiments, and they constitute a fundamental reference in nuclear physics to constrain nuclear interactions and the properties of n...

A bstract The angular correlations between charged Ξ baryons and associated identified hadrons (pions, kaons, protons, Λ baryons, and Ξ baryons) are measured in pp collisions at $$ \sqrt{s} $$ s = 13 TeV with the ALICE detector to give insight into the particle production mechanisms and balancing of quantum numbers on the microscopic level. In part...

A study of strange hadron production associated with hard scattering processes and with the underlying event is conducted to investigate the origin of the enhanced production of strange hadrons in small collision systems characterised by large charged-particle multiplicities. For this purpose, the production of the single-strange meson \( {\textrm{...

A bstract The azimuthal anisotropy of particles associated with jets (jet particles) at midrapidity is measured for the first time in p-Pb and Pb-Pb collisions at $$ \sqrt{{\textrm{s}}_{\textrm{NN}}} $$ s NN = 5 . 02 TeV down to transverse momentum ( p T ) of 0.5 GeV/ c and 2 GeV/ c , respectively, with ALICE. The results obtained in p-Pb collision...

This Letter presents the most precise measurement to date of the matter-antimatter imbalance at midrapidity in Pb-Pb collisions at a center-of-mass energy per nucleon pair s NN = 5.02 TeV . Using the Statistical Hadronization framework, it is possible to obtain the value of the electric charge and baryon chemical potentials, μ Q = − 0.18 ± 0.90 MeV...

The ALICE experiment was proposed in 1993, to study strongly-interacting matter at extreme energy densities and temperatures. This proposal entailed a comprehensive investigation of nuclear collisions at the LHC. Its physics programme initially focused on the determination of the properties of the quark–gluon plasma (QGP), a deconfined state of qua...

The inclusive production of the charm-strange baryon Ω c 0 is measured for the first time via its semileptonic decay into Ω − e + ν e at midrapidity ( | y | < 0.8 ) in proton-proton (pp) collisions at the center-of-mass energy s = 13 TeV with the ALICE detector at the LHC. The transverse momentum ( p T ) differential cross section multiplied by the...

The two-particle momentum correlation functions between charm mesons ( D * ± and D ± ) and charged light-flavor mesons ( π ± and K ± ) in all charge combinations are measured for the first time by the ALICE Collaboration in high-multiplicity proton–proton collisions at a center-of-mass energy of s = 13 TeV . For DK and D * K pairs, the experimental...

The ALICE Collaboration reports measurements of the semi-inclusive distribution of charged-particle jets recoiling from a high transverse momentum (high p T ) charged hadron, in p p and central Pb-Pb collisions at center-of-mass energy per nucleon–nucleon collision s NN = 5.02 TeV. The large uncorrelated background in central Pb-Pb collisions is co...

The ALICE Collaboration reports the measurement of semi-inclusive distributions of charged-particle jets recoiling from a high transverse momentum (high p T ) hadron trigger in proton-proton and central Pb-Pb collisions at s NN = 5.02 TeV . A data-driven statistical method is used to mitigate the large uncorrelated background in central Pb-Pb colli...

Measurements of the p T -dependent flow vector fluctuations in Pb–Pb collisions at s NN = 5.02 TeV using azimuthal correlations with the ALICE experiment at the Large Hadron Collider are presented. A four-particle correlation approach [ALICE Collaboration, ] is used to quantify the effects of flow angle and magnitude fluctuations separately. This p...

K + K − pairs may be produced in photonuclear collisions, either from the decays of photoproduced ϕ ( 1020 ) mesons or directly as nonresonant K + K − pairs. Measurements of K + K − photoproduction probe the couplings between the ϕ ( 1020 ) and charged kaons with photons and nuclear targets. The kaon-proton scattering occurs at energies far above t...

A bstract The production yields of the Σ(1385) ± and Ξ(1530) ⁰ resonances are measured in pp collisions at $$ \sqrt{s} $$ s = 13 TeV with ALICE. The measurements are performed as a function of the charged-particle multiplicity ⟨d N ch / d η ⟩, which is related to the energy density produced in the collision. The results include transverse momentum...

A Large Ion Collider Experiment (ALICE) has been conceived and constructed as a heavy-ion experiment at the LHC. During LHC Runs 1 and 2, it has produced a wide range of physics results using all collision systems available at the LHC. In order to best exploit new physics opportunities opening up with the upgraded LHC and new detector technologies,...

A bstract Results on the transverse spherocity dependence of light-flavor particle production ( π , K, p, ϕ , K *0 , $$ {\textrm{K}}_{\textrm{S}}^0 $$ K S 0 , Λ, Ξ) at midrapidity in high-multiplicity pp collisions at $$ \sqrt{s} $$ s = 13 TeV were obtained with the ALICE apparatus. The transverse spherocity estimator $$ \left({S}_{\textrm{O}}^{p_{...

A bstract Measurements of inclusive charged-particle jet production in pp and p-Pb collisions at center-of-mass energy per nucleon-nucleon collision $$ \sqrt{s_{\textrm{NN}}} $$ s NN = 5 . 02 TeV and the corresponding nuclear modification factor $$ {R}_{\textrm{pPb}}^{\textrm{ch}\ \textrm{jet}} $$ R pPb ch jet are presented, using data collected wi...

A bstract The ALICE Collaboration reports a search for jet quenching effects in high-multiplicity (HM) proton-proton collisions at $$ \sqrt{s} $$ s = 13 TeV, using the semi-inclusive azimuthal-difference distribution ∆ φ of charged-particle jets recoiling from a high transverse momentum (high- p T , trig ) trigger hadron. Jet quenching may broaden...

This Letter presents the measurement of near-side associated per-trigger yields, denoted ridge yields, from the analysis of angular correlations of charged hadrons in proton-proton collisions at s = 13 TeV . Long-range ridge yields are extracted for pairs of charged particles with a pseudorapidity difference of 1.4 < | Δ η | < 1.8 and a transverse...

The first measurement of the cross section for incoherent photonuclear production of J / ψ vector mesons as a function of the Mandelstam | t | variable is presented. The measurement was carried out with the ALICE detector at midrapidity, | y | < 0.8 , using ultraperipheral collisions of Pb nuclei at a center-of-mass energy per nucleon pair of s NN...

Recent measurements of charm-baryon production in hadronic collisions have questioned the universality of charm-quark fragmentation across different collision systems. In this work the fragmentation of charm quarks into charm baryons is probed, by presenting the first measurement of the longitudinal jet momentum fraction carried by Λ c + baryons, z...

The production of K * ( 892 ) ± meson resonance is measured at midrapidity ( | y | < 0.5 ) in Pb − Pb collisions at s N N = 5.02 TeV using the ALICE detector at the CERN Large Hadron Collider. The resonance is reconstructed via its hadronic decay channel K * ( 892 ) ± → K S 0 π ± . The transverse momentum distributions are obtained for various cent...

A bstract Long- and short-range correlations for pairs of charged particles are studied via two-particle angular correlations in pp collisions at $$ \sqrt{s} $$ s = 13 TeV and p–Pb collisions at $$ \sqrt{s_{\textrm{NN}}} $$ s NN = 5 . 02 TeV. The correlation functions are measured as a function of relative azimuthal angle ∆ φ and pseudorapidity sep...

Collective behavior has been observed in high-energy heavy-ion collisions for several decades. Collectivity is driven by the high particle multiplicities that are produced in these collisions. At the CERN Large Hadron Collider (LHC), features of collectivity have also been seen in high-multiplicity proton-proton collisions that can attain particle...

A bstract The transverse momentum ( p T ) and centrality dependence of the nuclear modification factor R AA of prompt and non-prompt J/ ψ , the latter originating from the weak decays of beauty hadrons, have been measured by the ALICE collaboration in Pb–Pb collisions at $$ \sqrt{s_{\textrm{NN}}} $$ s NN = 5.02 TeV. The measurements are carried out...

A bstract Correlations in azimuthal angle extending over a long range in pseudorapidity between particles, usually called the “ridge” phenomenon, were discovered in heavy-ion collisions, and later found in pp and p–Pb collisions. In large systems, they are thought to arise from the expansion (collective flow) of the produced particles. Extending th...

The first measurements of K * ( 892 ) 0 resonance production as a function of charged-particle multiplicity in Xe-Xe collisions at s N N = 5.44 TeV and p p collisions at s = 5.02 TeV using the ALICE detector are presented. The resonance is reconstructed at midrapidity ( | y | < 0.5) using the hadronic decay channel K * 0 → K ± π ∓ . Measurements of...

The production of the ψ ( 2 S ) charmonium state was measured with ALICE in Pb-Pb collisions at s NN = 5.02 TeV , in the dimuon decay channel. A significant signal was observed for the first time at LHC energies down to zero transverse momentum, at forward rapidity ( 2.5 < y < 4 ). The measurement of the ratio of the inclusive production cross sect...

A bstract Measurements of charged-particle production in pp, p–Pb, and Pb–Pb collisions in the toward, away, and transverse regions with the ALICE detector are discussed. These regions are defined event-by-event relative to the azimuthal direction of the charged trigger particle, which is the reconstructed particle with the largest transverse momen...

A bstract Measurements of the production cross sections of prompt D ⁰ , D ⁺ , D *+ , $$ {\textrm{D}}_{\textrm{s}}^{+} $$ D s + , $$ {\Lambda}_{\textrm{c}}^{+} $$ Λ c + , and $$ {\Xi}_{\textrm{c}}^{+} $$ Ξ c + charm hadrons at midrapidity in proton-proton collisions at $$ \sqrt{s} $$ s = 13 TeV with the ALICE detector are presented. The D-meson cros...

A bstract The Chiral Magnetic Wave (CMW) phenomenon is essential to provide insights into the strong interaction in QCD, the properties of the quark-gluon plasma, and the topological characteristics of the early universe, offering a deeper understanding of fundamental physics in high-energy collisions. Measurements of the charge-dependent anisotrop...

The production cross sections of D0 and Λc+ hadrons originating from beauty-hadron decays (i.e., nonprompt) were measured for the first time at midrapidity (|y|<0.5) by the ALICE Collaboration in proton-proton collisions at a center-of-mass energy s=13 TeV. They are described within uncertainties by perturbative QCD calculations employing the fragm...

The elliptic flow \((v_2)\) of \({\textrm{D}}^{0}\) mesons from beauty-hadron decays (non-prompt \({\textrm{D}}^{0})\) was measured in midcentral (30–50%) Pb–Pb collisions at a centre-of-mass energy per nucleon pair \(\sqrt{s_{\textrm{NN}}} = 5.02\) TeV with the ALICE detector at the LHC. The \({\textrm{D}}^{0}\) mesons were reconstructed at midrap...

The interactions of kaons (K) and antikaons (\(\mathrm {\overline{K}}\)) with few nucleons (N) were studied so far using kaonic atom data and measurements of kaon production and interaction yields in nuclei. Some details of the three-body KNN and \(\mathrm {\overline{K}}\)NN dynamics are still not well understood, mainly due to the overlap with mul...

Understanding the role of parton mass and Casimir color factors in the quantum chromodynamics parton shower represents an important step in characterizing the emission properties of heavy quarks. Recent experimental advances in jet substructure techniques have provided the opportunity to isolate and characterize gluon emissions from heavy quarks. I...

Measurements of the elliptic flow coefficient relative to the collision plane defined by the spectator neutrons v2{ΨSP} in collisions of Pb ions at center-of-mass energy per nucleon–nucleon pair sNN=2.76 TeV and Xe ions at sNN=5.44 TeV are reported. The results are presented for charged particles produced at midrapidity as a function of centrality...

A bstract The cross section for coherent photonuclear production of J/ ψ is presented as a function of the electromagnetic dissociation (EMD) of Pb. The measurement is performed with the ALICE detector in ultra-peripheral Pb-Pb collisions at a centre-of-mass energy per nucleon pair of $$ \sqrt{{\textrm{s}}_{\textrm{NN}}} $$ s NN = 5.02 TeV. Cross s...

A bstract The fractions of non-prompt (i.e. originating from beauty-hadron decays) D ⁰ and D ⁺ mesons with respect to the inclusive yield are measured as a function of the charged-particle multiplicity in proton-proton collisions at a centre-of-mass energy of $$ \sqrt{s} $$ s = 13 TeV with the ALICE detector at the LHC. The results are reported in...

The first experimental information on the strong interaction between Λ and Ξ− strange baryons is presented in this Letter. The correlation function of Λ–Ξ− and Λ‾–Ξ‾+ pairs produced in high-multiplicity proton–proton (pp) collisions at s=13 TeV at the LHC is measured as a function of the relative momentum of the pair. The femtoscopy method is used...

A bstract Measurements of the production of electrons from heavy-flavour hadron decays in pp collisions at $$ \sqrt{s} $$ s = 13 TeV at midrapidity with the ALICE detector are presented down to a transverse momentum ( p T ) of 0.2 GeV/ c and up to p T = 35 GeV/ c , which is the largest momentum range probed for inclusive electron measurements in AL...

The transverse-momentum (p_{T}) spectra and coalescence parameters B_{2} of (anti)deuterons are measured in p-p collisions at sqrt[s]=13 TeV for the first time in and out of jets. In this measurement, the direction of the leading particle with the highest p_{T} in the event (p_{T}^{lead}>5 GeV/c) is used as an approximation for the jet axis. The ev...

A bstract This article reports measurements of the angle between differently defined jet axes in pp collisions at $$ \sqrt{s} $$ s = 5 . 02 TeV carried out by the ALICE Collaboration. Charged particles at midrapidity are clustered into jets with resolution parameters R = 0 . 2 and 0.4. The jet axis, before and after Soft Drop grooming, is compared...

A bstract Production of inclusive charmonia in pp collisions at center-of-mass energy of $$ \sqrt{s} $$ s = 13 TeV and p–Pb collisions at center-of-mass energy per nucleon pair of $$ \sqrt{s_{\textrm{NN}}} $$ s NN = 8 . 16 TeV is studied as a function of charged-particle pseudorapidity density with ALICE. Ground and excited charmonium states ( J/ψ...

A bstract The measurement of the production of charm jets, identified by the presence of a D ⁰ meson in the jet constituents, is presented in proton–proton collisions at centre-of-mass energies of $$ \sqrt{s} $$ s = 5.02 and 13 TeV with the ALICE detector at the CERN LHC. The D ⁰ mesons were reconstructed from their hadronic decay D ⁰ → K − π ⁺ and...

A bstract The production of π ± , K ± , and $$ \left(\overline{\textrm{p}}\right)\textrm{p} $$ p ¯ p is measured in pp collisions at $$ \sqrt{s} $$ s = 13 TeV in different topological regions of the events. Particle transverse momentum ( p T ) spectra are measured in the “toward”, “transverse”, and “away” angular regions defined with respect to the...

A bstract The first measurement of the e ⁺ e − pair production at low lepton pair transverse momentum ( p T , ee ) and low invariant mass ( m ee ) in non-central Pb–Pb collisions at $$ {\sqrt{s}}_{\textrm{NN}} $$ s NN = 5 . 02 TeV at the LHC is presented. The dielectron production is studied with the ALICE detector at midrapidity ( |η e | < 0 . 8)...

A bstract The first measurements of elliptic flow of π ± , K ± , $$ \textrm{p}+\overline{\textrm{p}} $$ p + p ¯ , $$ {\textrm{K}}_{\textrm{S}}^0 $$ K S 0 , $$ \Lambda +\overline{\Lambda} $$ Λ + Λ ¯ , ϕ , $$ {\Xi}^{-}+{\overline{\Xi}}^{+} $$ Ξ − + Ξ ¯ + , and $$ {\varOmega}^{-}+{\overline{\varOmega}}^{+} $$ Ω − + Ω ¯ + using multiparticle cumulants...

This article presents new measurements of the fragmentation properties of jets in both proton–proton (pp) and heavy-ion collisions with the ALICE experiment at the Large Hadron Collider (LHC). We report distributions of the fraction z r of transverse momentum carried by subjets of radius r within jets of radius R . Charged-particle jets are reconst...

Two-particle transverse momentum differential correlators, recently measured in Pb-Pb collisions at energies available at the CERN Large Hadron Collider (LHC), provide an additional tool to gain insights into particle production mechanisms and infer transport properties, such as the ratio of shear viscosity to entropy density, of the medium created...

The production of K*(892)0and ϕ(1020)resonances has been measured in p-Pb collisions at sNN = 8.16 TeV using the ALICE detector. Resonances are reconstructed via their hadronic decay channels in the rapidity interval −0.5 < y < 0 and the transverse momentum spectra are measured for various multiplicity classes up to pT = 20 GeV/c for K*(892)0and pT...

The production of the W± bosons measured in p–Pb collisions at a centre-of-mass energy per nucleon–nucleon collision \( \sqrt{s_{\textrm{NN}}} \) = 8.16 TeV and Pb–Pb collisions at \( \sqrt{s_{\textrm{NN}}} \) = 5.02 TeV with ALICE at the LHC is presented. The W± bosons are measured via their muonic decay channel, with the muon reconstructed in the...

Measurements of the production of electrons from heavy-flavour hadron decays in pp collisions at $\sqrt{s} = 13$ TeV at midrapidity with the ALICE detector are presented down to a transverse momentum ($p_{\rm T}$) of 0.2 GeV$/c$ and up to $p_{\rm T} = 35$ GeV$/c$, which is the largest momentum range probed for inclusive electron measurements in ALI...

The modern life of businesses is categorically reliant on their established position online, where digital (and particularly website) content plays a significant role as the first point of information. Digital content, therefore, becomes essential-from making the first impression through to the building and development of client relationships. Desp...

The production of prompt Λc+ baryons at midrapidity (|y

This article reports on the inclusive production cross section of several quarkonium states, \(\textrm{J}/\psi \), \(\psi \mathrm{(2S)}\), \(\Upsilon \mathrm (1S)\), \(\Upsilon \mathrm{(2S)}\), and \(\Upsilon \mathrm{(3S)}\), measured with the ALICE detector at the LHC, in pp collisions at \(\sqrt{s} = 5.02\) TeV. The analysis is performed in the d...

A bstract The production of non-prompt D ⁰ mesons from beauty-hadron decays was measured at midrapidity (| y | < 0 . 5) in Pb-Pb collisions at a nucleon-nucleon center-of-mass energy of $$ \sqrt{{\textrm{s}}_{\textrm{NN}}} $$ s NN = 5 . 02 TeV with the ALICE experiment at the LHC. Their nuclear modification factor ( R AA ), measured for the first t...

In our Galaxy, light antinuclei composed of antiprotons and antineutrons can be produced through high-energy cosmic-ray collisions with the interstellar medium or could also originate from the annihilation of dark-matter particles that have not yet been discovered. On Earth, the only way to produce and study antinuclei with high precision is to cre...

The production of non-prompt D0 mesons from beauty-hadron decays was measured at midrapidity (|y| < 0.5) in Pb-Pb collisions at a nucleon-nucleon center-of-mass energy of \( \sqrt{{\textrm{s}}_{\textrm{NN}}} \) = 5.02 TeV with the ALICE experiment at the LHC. Their nuclear modification factor (RAA), measured for the first time down to pT = 1 GeV/c...

This article presents the first measurement of the interaction between charm hadrons and nucleons. The two-particle momentum correlations of pD− and p¯D+ pairs are measured by the ALICE Collaboration in high-multiplicity pp collisions at s=13 TeV. The data are compatible with the Coulomb-only interaction hypothesis within (1.1–1.5)σ. The level of a...

The production of K*(892)0 and ϕ(1020) mesons in proton–proton (pp) and lead–lead (Pb–Pb) collisions at sNN = 5.02 TeV has been measured using the ALICE detector at the Large Hadron Collider (LHC). The transverse momentum (pT) distributions of K*(892)0 and ϕ(1020) mesons have been measured at midrapidity (|y|<0.5) up to pT= 20 GeV/c in inelastic pp...

A bstract The energy deposited at very forward rapidities (very forward energy) is a powerful tool for characterising proton fragmentation in pp and p-Pb collisions. The correlation of very forward energy with particle production at midrapidity provides direct insights into the initial stages and the subsequent evolution of the collision. Furthermo...