Ryan CookeCentre for Extragalactic Astronomy, Durham University
One of the most compelling pieces of evidence of the Hot Big Bang model is the realisation and confirmation that some nuclides were created shortly after the Big Bang. This process is referred to as Big Bang nucleosynthesis (or, sometimes, primordial nucleosynthesis), and is the end-product of putting neutrons and protons in a hot, expanding Universe. Big Bang nucleosynthesis currently provides our earliest test of cosmology, and it is the only experiment currently designed that is simultaneously sensitive to all four known fundamental forces: the gravitational force, the electromagnetic force, the strong force and the weak force. Our theoretical understanding of Big Bang nucleosynthesis and the measurement of the primordial abundances together represents one of the strongest pillars of the standard cosmological model. In this chapter, we will develop an intuitive understanding of Big Bang nucleosynthesis, discuss modern calculations of this process, and provide a summary of the current state-of-the-art measurements that have been made. Overall, Big Bang nucleosynthesis is in remarkable agreement with various cosmological probes, and it is this agreement that serves to strengthen our confidence in the general picture of cosmology that we have today.
{"title":"Big Bang Nucleosynthesis","authors":"Ryan CookeCentre for Extragalactic Astronomy, Durham University","doi":"arxiv-2409.06015","DOIUrl":"https://doi.org/arxiv-2409.06015","url":null,"abstract":"One of the most compelling pieces of evidence of the Hot Big Bang model is\u0000the realisation and confirmation that some nuclides were created shortly after\u0000the Big Bang. This process is referred to as Big Bang nucleosynthesis (or,\u0000sometimes, primordial nucleosynthesis), and is the end-product of putting\u0000neutrons and protons in a hot, expanding Universe. Big Bang nucleosynthesis\u0000currently provides our earliest test of cosmology, and it is the only\u0000experiment currently designed that is simultaneously sensitive to all four\u0000known fundamental forces: the gravitational force, the electromagnetic force,\u0000the strong force and the weak force. Our theoretical understanding of Big Bang\u0000nucleosynthesis and the measurement of the primordial abundances together\u0000represents one of the strongest pillars of the standard cosmological model. In\u0000this chapter, we will develop an intuitive understanding of Big Bang\u0000nucleosynthesis, discuss modern calculations of this process, and provide a\u0000summary of the current state-of-the-art measurements that have been made.\u0000Overall, Big Bang nucleosynthesis is in remarkable agreement with various\u0000cosmological probes, and it is this agreement that serves to strengthen our\u0000confidence in the general picture of cosmology that we have today.","PeriodicalId":501573,"journal":{"name":"arXiv - PHYS - Nuclear Theory","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206819","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We discuss how to extract numerically the expected lowest quasi-normal mode (QNM) associated with the pressure anisotropy for a Bjorken flux evolution to equilibrium. This QNM was easily decoded subtracting the hydrodynamical attractors and was compared with other authors calculations. After evolutions with transients close to the expected lowest QNM the system goes to a tail (pure imaginary frequency) for late times. We analyze the relevance of Navier-Stokes, second order and Borel attractors at each stage of the evolution, which begins far-from-equilibrium and ends close to equilibrium.
{"title":"Are these quasi-normal modes?","authors":"Gustavo Godinho, Willians Barreto","doi":"arxiv-2409.05930","DOIUrl":"https://doi.org/arxiv-2409.05930","url":null,"abstract":"We discuss how to extract numerically the expected lowest quasi-normal mode\u0000(QNM) associated with the pressure anisotropy for a Bjorken flux evolution to\u0000equilibrium. This QNM was easily decoded subtracting the hydrodynamical\u0000attractors and was compared with other authors calculations. After evolutions\u0000with transients close to the expected lowest QNM the system goes to a tail\u0000(pure imaginary frequency) for late times. We analyze the relevance of\u0000Navier-Stokes, second order and Borel attractors at each stage of the\u0000evolution, which begins far-from-equilibrium and ends close to equilibrium.","PeriodicalId":501573,"journal":{"name":"arXiv - PHYS - Nuclear Theory","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yacine Mehtar-Tani, Felix Ringer, Balbeer Singh, Varun Vaidya
We develop an Effective Field Theory approach for jet observables in heavy-ion collisions, where the jet is treated as an open quantum system interacting with a hot and dense QCD medium. Within this framework, we derive a novel factorization formula for inclusive jet production, expressed as a series expansion with an increasing number of radiating subjet functions that encode forward scattering with the Quark-Gluon Plasma, convolved with perturbative matching coefficients. This work provides a systematic framework for computing jet observables at higher order and understanding their non-perturbative aspects, paving the way for future applications in heavy-ion phenomenology.
{"title":"Factorization for jet production in heavy-ion collisions","authors":"Yacine Mehtar-Tani, Felix Ringer, Balbeer Singh, Varun Vaidya","doi":"arxiv-2409.05957","DOIUrl":"https://doi.org/arxiv-2409.05957","url":null,"abstract":"We develop an Effective Field Theory approach for jet observables in\u0000heavy-ion collisions, where the jet is treated as an open quantum system\u0000interacting with a hot and dense QCD medium. Within this framework, we derive a\u0000novel factorization formula for inclusive jet production, expressed as a series\u0000expansion with an increasing number of radiating subjet functions that encode\u0000forward scattering with the Quark-Gluon Plasma, convolved with perturbative\u0000matching coefficients. This work provides a systematic framework for computing\u0000jet observables at higher order and understanding their non-perturbative\u0000aspects, paving the way for future applications in heavy-ion phenomenology.","PeriodicalId":501573,"journal":{"name":"arXiv - PHYS - Nuclear Theory","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206543","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nuclear transparency in pion-induced nuclear reactions has been investigated on the basis of Glauber multiple scattering theory considering a two-step process within the framework of vector meson dominance (VMD). In the present context, the application of the quantum diffusion model (QDM) to the Glauber theory plays a role in explaining the dependence of the transparency on the four momentum transfer squared $Q^2$. % as shown in the experimental data. The short-range correlation (SRC) considered further gives the contribution to the magnitude of the transparency by a constant amount independent of the $Q^2$ variation, and the results from the QDM and SRC overestimate the experimental data. The inclusion of the two-step process with the $rho N$ scattering cross section, $sigma_{rho N}=3 $ mb has the effect of reducing the transparency and thus leads to a good agreement with the experimental data on the reaction $A(e,e'pi^+)$ for $^{12}$C, $^{27}$Al, $^{63}$Cu and $^{197}$Au nuclei.
{"title":"Nuclear transparencies with a two step process of the $A(e,e'π^+)$ reactions","authors":"Tae Keun Choi, Kook-Jin Kong, Byung-Geel Yu","doi":"arxiv-2409.05129","DOIUrl":"https://doi.org/arxiv-2409.05129","url":null,"abstract":"Nuclear transparency in pion-induced nuclear reactions has been investigated\u0000on the basis of Glauber multiple scattering theory considering a two-step\u0000process within the framework of vector meson dominance (VMD). In the present\u0000context, the application of the quantum diffusion model (QDM) to the Glauber\u0000theory plays a role in explaining the dependence of the transparency on the\u0000four momentum transfer squared $Q^2$. % as shown in the experimental data. The\u0000short-range correlation (SRC) considered further gives the contribution to the\u0000magnitude of the transparency by a constant amount independent of the $Q^2$\u0000variation, and the results from the QDM and SRC overestimate the experimental\u0000data. The inclusion of the two-step process with the $rho N$ scattering cross\u0000section, $sigma_{rho N}=3 $ mb has the effect of reducing the transparency\u0000and thus leads to a good agreement with the experimental data on the reaction\u0000$A(e,e'pi^+)$ for $^{12}$C, $^{27}$Al, $^{63}$Cu and $^{197}$Au nuclei.","PeriodicalId":501573,"journal":{"name":"arXiv - PHYS - Nuclear Theory","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We extract the leading Fock-state light front wave functions (LF-LFWFs) of heavy flavor-asymmetric pseudoscalar mesons $D$, $B$ and $B_c$ from their Bethe-Salpeter wave functions based on Dyson-Schwinger equations approach, and study their leading twist parton distribution amplitudes, generalized parton distribution functions and transverse momentum dependent parton distributions. The spatial distributions of the quark and antiquark on the transverse plane are given, along with their charge and energy distributions on the light front. We find that in the considered mesons, the heavier quarks carry most longitudinal momentum fraction and yield narrow $x$-distributions, while the lighter quarks play an active role in shaping the transverse distributions within both spatial and momentum space, exhibiting a duality embodying characteristics from both light mesons and heavy quarkonium.
{"title":"Heavy flavor-asymmetric pseudoscalar mesons on the light front","authors":"Chao Shi, Pengfei Liu, Yi-Lun Du, Wenbao Jia","doi":"arxiv-2409.05098","DOIUrl":"https://doi.org/arxiv-2409.05098","url":null,"abstract":"We extract the leading Fock-state light front wave functions (LF-LFWFs) of\u0000heavy flavor-asymmetric pseudoscalar mesons $D$, $B$ and $B_c$ from their\u0000Bethe-Salpeter wave functions based on Dyson-Schwinger equations approach, and\u0000study their leading twist parton distribution amplitudes, generalized parton\u0000distribution functions and transverse momentum dependent parton distributions.\u0000The spatial distributions of the quark and antiquark on the transverse plane\u0000are given, along with their charge and energy distributions on the light front.\u0000We find that in the considered mesons, the heavier quarks carry most\u0000longitudinal momentum fraction and yield narrow $x$-distributions, while the\u0000lighter quarks play an active role in shaping the transverse distributions\u0000within both spatial and momentum space, exhibiting a duality embodying\u0000characteristics from both light mesons and heavy quarkonium.","PeriodicalId":501573,"journal":{"name":"arXiv - PHYS - Nuclear Theory","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhiyi Wang, Jinhui Chen, Diyu Shen, Aihong Tang, Gang Wang
The chiral magnetic effect (CME) in heavy-ion collisions reflects the local violation of ${cal P}$ and ${cal CP}$ symmetries in strong interactions and manifests as electric charge separation along the direction of the magnetic field created by the wounded nuclei. The experimental observables for the CME, such as the $gamma_{112}$ correlator, the $R_{Psi_2}(Delta S)$ correlator, and the signed balance functions, however, are also subject to non-CME backgrounds, including those from resonance decays. A previous study showed that the CME observables are affected by the diagonal component of the spin density matrix, the $rho_{00}$ for vector mesons. In this work, we study the contributions from the other elements of the spin density matrix using a toy model and a multiphase transport model. We find that the real part of the $rho_{1-1}$ component, $mathrm{Re},rho_{1-1}$, affects the CME observables in a manner opposite to that of the $rho_{00}$. All three aforementioned CME observables show a linear dependence on $mathrm{Re},rho_{1-1}$ in the model calculations, supporting our analytical derivations. The rest elements of the spin density matrix do not contribute to the CME observables. The off-diagonal terms in the spin density matrix indicate spin coherence and may be nonzero in heavy-ion collisions due to local spin polarization or spin-spin correlations. Thus, $mathrm{Re},rho_{1-1}$, along with $rho_{00}$, could play a significant role in interpreting measurements in search of the CME.
{"title":"Effect of vector meson spin coherence on the measurements of chiral magnetic effect in heavy-ion collisions","authors":"Zhiyi Wang, Jinhui Chen, Diyu Shen, Aihong Tang, Gang Wang","doi":"arxiv-2409.04675","DOIUrl":"https://doi.org/arxiv-2409.04675","url":null,"abstract":"The chiral magnetic effect (CME) in heavy-ion collisions reflects the local\u0000violation of ${cal P}$ and ${cal CP}$ symmetries in strong interactions and\u0000manifests as electric charge separation along the direction of the magnetic\u0000field created by the wounded nuclei. The experimental observables for the CME,\u0000such as the $gamma_{112}$ correlator, the $R_{Psi_2}(Delta S)$ correlator,\u0000and the signed balance functions, however, are also subject to non-CME\u0000backgrounds, including those from resonance decays. A previous study showed\u0000that the CME observables are affected by the diagonal component of the spin\u0000density matrix, the $rho_{00}$ for vector mesons. In this work, we study the\u0000contributions from the other elements of the spin density matrix using a toy\u0000model and a multiphase transport model. We find that the real part of the\u0000$rho_{1-1}$ component, $mathrm{Re},rho_{1-1}$, affects the CME observables\u0000in a manner opposite to that of the $rho_{00}$. All three aforementioned CME\u0000observables show a linear dependence on $mathrm{Re},rho_{1-1}$ in the model\u0000calculations, supporting our analytical derivations. The rest elements of the\u0000spin density matrix do not contribute to the CME observables. The off-diagonal\u0000terms in the spin density matrix indicate spin coherence and may be nonzero in\u0000heavy-ion collisions due to local spin polarization or spin-spin correlations.\u0000Thus, $mathrm{Re},rho_{1-1}$, along with $rho_{00}$, could play a\u0000significant role in interpreting measurements in search of the CME.","PeriodicalId":501573,"journal":{"name":"arXiv - PHYS - Nuclear Theory","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142226251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Chanlaridis, D. Ohse, J. Antoniadis, D. Blaschke, D. E. Alvarez-Castillo, V. Danchev, D. Misra, N. Langer
Millisecond pulsars (MSPs) are laboratories for stellar evolution, strong gravity, and ultra-dense matter. Although MSPs are thought to originate in low-mass X-ray binaries (LMXBs), approximately 27% lack a binary companion, while others are found in systems with large orbital eccentricities. Understanding how these systems form may provide insight into the internal properties of neutron stars (NSs). We study the formation of a twin compact star through rapid first-order phase transitions in NS cores due to mass accretion in LMXBs. We investigate whether this mechanism, possibly coupled with secondary kick effects such as neutrino or electromagnetic rocket effects, may leave an observable long-lasting imprint on the orbit. We simulate mass accretion in LMXBs consisting of a NS and a low-mass main sequence companion, following the evolution of the NS mass, radius, and spin until a strong phase transition is triggered. For the NS structure, we assume a multipolytrope equation-of-state that allows for a sharp phase transition from hadronic to quark matter and satisfies observational constraints. We find that in compact binaries with relatively short pre-Roche lobe overflow orbital periods, an accretion-induced phase transition may occur during the LMXB phase. In contrast, in systems with wider orbits, this transition may take place during the spin-down phase, forming an eccentric binary MSP. If the transition is accompanied by a secondary kick (w > 20 km/s), the binary is likely to be disrupted, forming an isolated MSP or reconfigured to an ultra-wide orbit. Our results suggest that accretion in LMXBs provides a viable path for forming twin compact stars, potentially leaving an observable imprint on the orbit. The eccentricity distribution of binary MSPs with long (> 50 d) orbital periods could provide constraints on first-order phase transitions in dense nuclear matter.
{"title":"Formation of twin compact stars in low-mass X-ray binaries: Implications on eccentric and isolated millisecond pulsar populations","authors":"S. Chanlaridis, D. Ohse, J. Antoniadis, D. Blaschke, D. E. Alvarez-Castillo, V. Danchev, D. Misra, N. Langer","doi":"arxiv-2409.04755","DOIUrl":"https://doi.org/arxiv-2409.04755","url":null,"abstract":"Millisecond pulsars (MSPs) are laboratories for stellar evolution, strong\u0000gravity, and ultra-dense matter. Although MSPs are thought to originate in\u0000low-mass X-ray binaries (LMXBs), approximately 27% lack a binary companion,\u0000while others are found in systems with large orbital eccentricities.\u0000Understanding how these systems form may provide insight into the internal\u0000properties of neutron stars (NSs). We study the formation of a twin compact star through rapid first-order phase\u0000transitions in NS cores due to mass accretion in LMXBs. We investigate whether\u0000this mechanism, possibly coupled with secondary kick effects such as neutrino\u0000or electromagnetic rocket effects, may leave an observable long-lasting imprint\u0000on the orbit. We simulate mass accretion in LMXBs consisting of a NS and a low-mass main\u0000sequence companion, following the evolution of the NS mass, radius, and spin\u0000until a strong phase transition is triggered. For the NS structure, we assume a\u0000multipolytrope equation-of-state that allows for a sharp phase transition from\u0000hadronic to quark matter and satisfies observational constraints. We find that in compact binaries with relatively short pre-Roche lobe\u0000overflow orbital periods, an accretion-induced phase transition may occur\u0000during the LMXB phase. In contrast, in systems with wider orbits, this\u0000transition may take place during the spin-down phase, forming an eccentric\u0000binary MSP. If the transition is accompanied by a secondary kick (w > 20 km/s),\u0000the binary is likely to be disrupted, forming an isolated MSP or reconfigured\u0000to an ultra-wide orbit. Our results suggest that accretion in LMXBs provides a viable path for\u0000forming twin compact stars, potentially leaving an observable imprint on the\u0000orbit. The eccentricity distribution of binary MSPs with long (> 50 d) orbital\u0000periods could provide constraints on first-order phase transitions in dense\u0000nuclear matter.","PeriodicalId":501573,"journal":{"name":"arXiv - PHYS - Nuclear Theory","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. G. Magner, S. P. Maydanyuk, A. Bonasera, H. Zheng, T. Depastas, A. I. Levon, U. V. Grygoriev
The macroscopic model for a neutron star (NS) as a liquid drop at the equilibrium is used to extend the Tolman-Oppenheimer-Volkoff (TOV) equations taking into account the gradient terms responsible for the system surface. The parameters of the Schwarzschild metric in the spherical case are found with these surface corrections in the leading (zero) order of the leptodermic approximation $a/R<<1$, where $a$ is the NS effective-surface (ES) thickness, and $R$ is the effective NS radius. The energy density $mathcal{E}$ is considered in a general form including the functions of the particle number density and of its gradient terms. The macroscopic gravitational potential $Phi(rho)$ is taken into account in the simplest form as expansion in powers of $rho-overline{rho} $, where $overline{rho}$ is the saturation density, up to second order, in terms of its contributions to th separation particle energy and incompressibility. Density distributions $rho$ across the NS ES in the normal direction to the ES, which are derived in the simple analytical form at the same leading approximation, was used for the derivation of the modified TOV (MTOV) equations by accounting for their NS surface corrections. The MTOV equations are analytically solved at first order and the results are compared with the standard TOV approach of the zero order.
{"title":"Leptodermic corrections to the TOV equations and nuclear astrophysics within the effective surface approximation","authors":"A. G. Magner, S. P. Maydanyuk, A. Bonasera, H. Zheng, T. Depastas, A. I. Levon, U. V. Grygoriev","doi":"arxiv-2409.04745","DOIUrl":"https://doi.org/arxiv-2409.04745","url":null,"abstract":"The macroscopic model for a neutron star (NS) as a liquid drop at the\u0000equilibrium is used to extend the Tolman-Oppenheimer-Volkoff (TOV) equations\u0000taking into account the gradient terms responsible for the system surface. The parameters of the\u0000Schwarzschild metric in the spherical case are found with these surface\u0000corrections in the leading (zero) order of the leptodermic approximation $a/R<<1$, where $a$ is\u0000the NS effective-surface (ES) thickness, and $R$ is the effective NS radius.\u0000The energy density $mathcal{E}$ is considered in a general form including the functions\u0000of the particle number density and of its gradient terms. The macroscopic\u0000gravitational potential $Phi(rho)$ is taken into account in the simplest form as\u0000expansion in powers of $rho-overline{rho} $, where $overline{rho}$ is the\u0000saturation density, up to second order, in terms of its contributions to th separation particle\u0000energy and incompressibility. Density distributions $rho$ across the NS ES in\u0000the normal direction to the ES, which are derived in the simple analytical form at the\u0000same leading approximation, was used for the derivation of the modified TOV\u0000(MTOV) equations by accounting for their NS surface corrections. The MTOV equations are\u0000analytically solved at first order and the results are compared with the\u0000standard TOV approach of the zero order.","PeriodicalId":501573,"journal":{"name":"arXiv - PHYS - Nuclear Theory","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142226249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Using the approach derived by Caron-Huot and Gale from the BDMPS-Z formalism, we obtain medium-induced parton splitting rates in a Bjorken expanding QCD matter. We compare the rate with the case of a static medium and investigate the impact of the medium expansion on the splitting rate. We also consider the leading order in the opacity expansion and the harmonic oscillator solution. These approximations are recovered in the limits of small and large formation times, respectively.
{"title":"Medium-induced parton splitting in expanding QCD matter","authors":"Ismail Soudi","doi":"arxiv-2409.04806","DOIUrl":"https://doi.org/arxiv-2409.04806","url":null,"abstract":"Using the approach derived by Caron-Huot and Gale from the BDMPS-Z formalism,\u0000we obtain medium-induced parton splitting rates in a Bjorken expanding QCD\u0000matter. We compare the rate with the case of a static medium and investigate\u0000the impact of the medium expansion on the splitting rate. We also consider the\u0000leading order in the opacity expansion and the harmonic oscillator solution.\u0000These approximations are recovered in the limits of small and large formation\u0000times, respectively.","PeriodicalId":501573,"journal":{"name":"arXiv - PHYS - Nuclear Theory","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Recently [arXiv:2201.03852v2] the PANDA collaboration studied the feasibility of determining the spin and parity of the $Xi(1690)^{-}$and $Xi(1820)^{-}$ resonances in the $Lambda K^-$ system produced in $bar{p}p$ collisions via the reaction channel $overline{p} p rightarrow bar{Xi}^{+} Lambda K^{-}$. This contribution aims to study these reactions using a model-independent irreducible tensor formalism developed earlier. This study leads us to identify the partial-wave amplitude, which would be zero if $Xi(1690)^{-}$ or $Xi(1820)^{-}$ had spin-1/2, provided these resonances are produced at threshold (s-wave production).
{"title":"Partial-wave analysis to determine the spin of $Ξ(1690)^-$ and $Ξ(1820)^-$ produced in $overline{p}p$ annihilation","authors":"Deepak Pachattu","doi":"arxiv-2409.04886","DOIUrl":"https://doi.org/arxiv-2409.04886","url":null,"abstract":"Recently [arXiv:2201.03852v2] the PANDA collaboration studied the feasibility\u0000of determining the spin and parity of the $Xi(1690)^{-}$and $Xi(1820)^{-}$\u0000resonances in the $Lambda K^-$ system produced in $bar{p}p$ collisions via\u0000the reaction channel $overline{p} p rightarrow bar{Xi}^{+} Lambda K^{-}$.\u0000This contribution aims to study these reactions using a model-independent\u0000irreducible tensor formalism developed earlier. This study leads us to identify\u0000the partial-wave amplitude, which would be zero if $Xi(1690)^{-}$ or\u0000$Xi(1820)^{-}$ had spin-1/2, provided these resonances are produced at\u0000threshold (s-wave production).","PeriodicalId":501573,"journal":{"name":"arXiv - PHYS - Nuclear Theory","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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