Institute of Nuclear PhysicsUzbekistan Academy of Sciences
We point out an interesting connection between the mathematical framework of the Krylov basis, which is used to quantify quantum complexity, and the entanglement entropy in high-energy QCD. In particular, we observe that the cascade equation of the dipole model is equivalent to the SL(2,R)SL(2,R) Schrodinger equation in the Krylov basis. Consequently, the Krylov complexity corresponds to the average distribution of partons and the Krylov entropy is the counterpart the entanglement entropy computations of \cite{Kharzeev:2017qzs}. Our work not only brings new tools for exploring quantum information and complexity in QCD, but also gives hope for experimental tests of some of the recent, physical probes of quantum complexity.
We present the Monte Carlo event generator KK version 4.13 for precision predictions of the Electroweak Standard Model for the process e+effˉ+nγe^+e^-\to f\bar{f} +n\gamma, f=μ,τ,d,u,s,c,bf=\mu,\tau,d,u,s,c,b at centre of mass energies from τ\tau lepton threshold to 1TeV, that is for LEP, SLC, future Linear Colliders, b,c,τb,c,\tau-factories etc. Effects due to photon emission from initial beams and outgoing fermions are calculated in QED up to second order, including all interference effects, within Coherent Exclusive Exponentiation (CEEX), which is based on Yennie-Frautschi-Suura exponentiation. Electroweak corrections are included in first order, with higher order extensions, using the DIZET 6.x library. Final state quarks hadronize according to the parton shower model using JETSET. Beams can be polarized longitudinally and transversely. Decay of the tau leptons is simulated using the TAUOLA library, taking into account spin polarization effects as well. In particular the complete spin correlations density matrix of the initial state beams and final state tau's is incorporated in an exact manner. Effects due to beamstrahlung are simulated in a realistic way. The main improvements with respect to KORALZ are: (a) inclusion of the initial-final state QED interference, (b) inclusion of the exact matrix element for two photons, and (c) inclusion of the transverse spin correlations in τ\tau decays (as in KORALB).
Due to the high anticipated experimental precision at the Future Circular Collider FCC-ee (or other proposed e+ee^+e^- colliders, such as ILC, CLIC, or CEPC) for electroweak and Higgs-boson precision measurements, theoretical uncertainties may have, if unattended, an important impact on the interpretation of these measurements within the Standard Model (SM), and thus on constraints on new physics. Current theory uncertainties, which would dominate the total uncertainty, need to be strongly reduced through future advances in the calculation of multi-loop radiative corrections together with improved experimental and theoretical control of the precision of SM input parameters. This document aims to provide an estimate of the required improvement in calculational accuracy in view of the anticipated high precision at the FCC-ee. For the most relevant electroweak and Higgs-boson precision observables we evaluate the corresponding quantitative impact.
The accurate identification of heavy-flavour jets, those which originate from bottom or charm quarks, is crucial for precision studies of the Standard Model and searches for new physics. However, assigning flavour to jets presents significant challenges, primarily due to issues with infrared and collinear (IRC) safety. This paper aims to address these challenges by evaluating recently-proposed jet algorithms designed to be IRC-safe and applicable in high-precision measurements. We compare these algorithms across benchmark heavy-flavour production processes and kinematic regimes that are relevant for LHC phenomenology. Exploiting both fixed-order calculations in QCD as well as parton shower simulations, we analyse the infrared sensitivity of these new algorithms at different stages of the event evolution and compare to flavour-labelling strategies currently adopted by LHC collaborations. The results highlight that, while all algorithms lead to more robust flavour-assignments compared to current techniques, they vary in performance depending on the observable and energy regime. The study lays groundwork for robust, flavour-aware jet analyses in current and future collider experiments to maximise the physics potential of experimental data by reducing discrepancies between theoretical and experimental methods.
GRB 221009A is the brightest Gamma-Ray Burst (GRB) detected in more than 50 years of study. In this paper, we present observations in the X-ray and optical domains after the GRB obtained by the GRANDMA Collaboration (which includes observations from more than 30 professional and amateur telescopes) and the Insight-HXMT Collaboration. We study the optical afterglow with empirical fitting from GRANDMA+HXMT data, augmented with data from the literature up to 60 days. We then model numerically, using a Bayesian approach, the GRANDMA and HXMT-LE afterglow observations, that we augment with Swift-XRT and additional optical/NIR observations reported in the literature. We find that the GRB afterglow, extinguished by a large dust column, is most likely behind a combination of a large Milky-Way dust column combined with moderate low-metallicity dust in the host galaxy. Using the GRANDMA+HXMT-LE+XRT dataset, we find that the simplest model, where the observed afterglow is produced by synchrotron radiation at the forward external shock during the deceleration of a top-hat relativistic jet by a uniform medium, fits the multi-wavelength observations only moderately well, with a tension between the observed temporal and spectral evolution. This tension is confirmed when using the extended dataset. We find that the consideration of a jet structure (Gaussian or power-law), the inclusion of synchrotron self-Compton emission, or the presence of an underlying supernova do not improve the predictions, showing that the modelling of GRB22109A will require going beyond the most standard GRB afterglow model. Placed in the global context of GRB optical afterglows, we find the afterglow of GRB 221009A is luminous but not extraordinarily so, highlighting that some aspects of this GRB do not deviate from the global known sample despite its extreme energetics and the peculiar afterglow evolution.
The ratios of charged antiparticles to particles have been obtained for pions, kaons and protons near midrapidity in central Au+Au collisions at sqrt(s_NN) = 200 GeV. Ratios of / = 1.025 +/- 0.006 (stat.) +/- 0.018 (syst.), / = 0.95 +/- 0.03 (stat.) +/- 0.03 (syst.) and /

= 0.73 +/- 0.02 (stat.) +/- 0.03 (syst.) have been observed. The / and /

ratios are consistent with a baryochemical potential mu_B of 27 MeV, roughly a factor of 2 smaller than in sqrt(s_NN) = 130 GeV collisions. The data are compared to results from lower energies and model calculations. Our accurate measurements of the particle ratios impose stringent constraints on current and future models dealing with baryon production and transport.

We present extensive photometric and spectroscopic observations of the peculiar Type Ia supernova (SN Ia) 2022vqz. It shares many similarities with the SN 2002es-like SNe Ia, such as low luminosity (MB,max=18.11±0.16M_{B,\rm max}=-18.11\pm0.16 mag) and moderate post-peak decline rate (Δm15,B=1.33±0.11\Delta m_{15,B}=1.33\pm0.11 mag). The nickel mass synthesised in the explosion is estimated as 0.20±0.04 M0.20\pm0.04~{\rm M}_\odot from the bolometric light curve, which is obviously lower than that of normal SNe Ia. SN 2022vqz is also characterised by slowly expanding ejecta, with Si II velocities persisting around 7000 km s1^{-1} since 16 days before peak brightness, unique among all known SNe Ia. While all of these properties imply a lower-energy thermonuclear explosion that should leave a considerable amount of unburnt materials, the absent signature of unburnt carbon in spectra of SN 2022vqz is puzzling. A prominent early peak is clearly detected in the ATLAS cc- and oo-band light curves and in the ZTF grgr-band data within days after the explosion. Possible mechanisms for the early peak are discussed, including the sub-Chandrasekhar-mass double-detonation model and interaction of SN ejecta with circumstellar material. We find that both models face some difficulties in replicating all aspects of the observed data. As an alternative, we propose a hybrid C-O-Ne white dwarf as the progenitor of SN 2022vqz; it can simultaneously reconcile the tension between low ejecta velocity and the absence of carbon. We further discuss the diversity of SN 2002es-like objects and their origin in the context of different scenarios.
The current theoretical estimations lead to cross-sections for AAγγAAAA \to \gamma \gamma AA which are somewhat smaller than the measured ones by the ATLAS and CMS Collaborations, In our recent paper, we estimated the contribution of inelastic channels to the Light-by-Light (LbL) scattering in ultraperipheral collisions (UPC) of heavy ions, in which one or both of the incident nuclei dissociate (AAγγXYA A \to \gamma \gamma X Y where X,Y=A,AX, Y = A, A') due to the photon emission. These new mechanisms are related to extra emissions that are difficult to identify and may be misinterpreted as enhanced γγγγ\gamma \gamma \to \gamma \gamma scattering. We include processes of coupling of photons to individual nucleons in addition to coherent coupling to the whole nuclei. Both elastic (nucleon in the ground state) and inelastic (nucleon in an excited state) are taken into account. The inelastic nucleon fluxes are calculated using CTEQ18QED photon distribution in nucleon. The inelastic photon fluxes are shown and compared to standard photon fluxes in the nucleus. We present the ratio of the inelastic corrections to the standard contribution to the nuclear cross section. We find that for the ATLAS kinematics the inelastic corrections grow with MγγM_{\gamma \gamma} and rapidity difference. Our results indicate that the inelastic contributions can be of the order of 20-40 \% of the traditional (no nuclear excitation) predictions. We discuss also uncertainties due to the choice of factorization scale.
The smallness of the cross section of evaporation residues formed in the hot fusion reaction 48^{48}Ca+232^{232}Th is analyzed by the dinuclear system model (DNS). The capture probability has been calculated by solving the dynamical equations of motion for the relative distance between the centers-of-mass of the DNS nuclei. Fusion of nuclei is considered as evolution of the DNS to a stable compound nucleus. The fusion probability has a bell-like shape and quasifission is one of reasons causing smallness of the yield of the evaporation residues products. Another reason is the decrease of the fission barrier for the isotopes 275285^{275-285}Dm related with the shell effects in the neutron structure. The agreement of the theoretical results obtained for the yield of the evaporation residues with the experimental data measured in the Factory of superheavy elements of Joint Institute for Nuclear Research is well.
The distribution of bases spacing in human genome was investigated. An analysis of the frequency of occurrence in the human genome of different sequence lengths flanked by one type of nucleotide was carried out showing that the distribution has no self-similar (fractal) structure. The results nevertheless revealed several characteristic features: (i) the distribution for short-range spacing is quite similar to the purely stochastic sequences; (ii) the distribution for long-range spacing essentially deviates from the random sequence distribution, showing strong long-range correlations; (iii) the differences between (A, T) and (C, G) bases are quite significant; (iv) the spacing distribution displays tiny oscillations.
We present a unified topological and geometric analysis of charged Anti-de Sitter (AdS) black holes immersed in a quintessence field, incorporating infrared gravitational corrections arising from the Extended Uncertainty Principle (EUP). The latter modifies the standard Heisenberg uncertainty relation by introducing a minimal momentum/maximal length scale, which effectively captures long-wavelength quantum gravitational effects relevant to black hole thermodynamics in curved spacetimes. We derive analytic expressions for the corrected Hawking temperature, entropy and heat capacity in terms of the EUP deformation parameter. Furthermore, the inclusion of quintessence, characterized by barotropic indices ωq=23\omega_q = -\frac{2}{3} and ωq=13\omega_q = -\frac{1}{3}, modifies the black hole metric function. By studying the relaxation-time function τ(rh)\tau(r_h), we identify a number of inflection points that depends sensitively on the equation of state parameter of quintessence, indicating a nontrivial impact of the latter on the black hole phase structure. Applying Duan's topological current method to the off-shell free energy, we compute integer-valued winding numbers associated with each thermodynamic critical point. A parallel topological analysis of the photon sphere assigns charges ±1 \pm 1 to individual light rings, showing that quintessence effects can trigger the splitting or merging of photon spheres, while preserving the total exterior topological charge of 1-1.
Forward calorimetry in the PHOBOS detector has been used to study charged hadron production in d+Au, p+Au and n+Au collisions at sqrt(s_nn) = 200 GeV. The forward proton calorimeter detectors are described and a procedure for determining collision centrality with these detectors is detailed. The deposition of energy by deuteron spectator nucleons in the forward calorimeters is used to identify p+Au and n+Au collisions in the data. A weighted combination of the yield of p+Au and n+Au is constructed to build a reference for Au+Au collisions that better matches the isospin composition of the gold nucleus. The p_T and centrality dependence of the yield of this improved reference system is found to match that of d+Au. The shape of the charged particle transverse momentum distribution is observed to extrapolate smoothly from pbar+p to central d+Au as a function of the charged particle pseudorapidity density. The asymmetry of positively- and negatively-charged hadron production in p+Au is compared to that of n+Au. No significant asymmetry is observed at mid-rapidity. These studies augment recent results from experiments at the LHC and RHIC facilities to give a more complete description of particle production in p+A and d+A collisions, essential for the understanding the medium produced in high energy nucleus-nucleus collisions.
We present recent results based on the IR-improvement of unintegrable singularities in the infrared regime via amplitude-based resummation in QED×QCDSU(2)L×U1×SU(3)cQED \times QCD \subset SU(2)_L \times U_1 \times SU(3)_c. In the context of precision LHC//FCC physics, we focus on specific examples, such as the removal of QED contamination in PDFs evolved from data at Q022  GeV2{Q_0}^2 \sim 2\; {\text{GeV}}^2 and used in the evaluating precision observables in ppZ+Xˉ+Xpp \rightarrow Z + X \rightarrow \ell\bar{\ell} + X', in which we discuss new results and new issues.
This work is devoted to study the effects of Einstein-\AE ther gravity on the dynamics of magnetized particles orbiting a static, spherically symmetric and uncharged black hole immersed in an external asymptotically uniform magnetic field in both comoving and proper observers frames. The analysis is carried out by varying the free parameters c13c_{13} and c14c_{14} of the Einstein-\AE ther theory and noticing their impacts on the particle trajectories, radii of the innermost stable circular orbits (ISCOs), and the amount of center-of-mass energy produced as a result of the collision. The strength of the magnetic field and the location of circular orbits is significantly affected by varying the above free parameters. We have also made detailed comparisons between the effects of parameters of Einstein-\AE ther and spin of rotating Kerr black holes on ISCO followed by magnetized particles and noticed that both black holes depict similar behaviour for suitable values of c13c_{13}, c14c_{14}, spin and the magnetic coupling parameters which provide exactly the same values for the ISCO. Finally, we have analysed the cases when a static \AE ther black hole can be described as Schwarzschild black hole in modified gravity (MOG) with the corresponding values of the parameters of the black holes.
The PHOBOS experiment has measured the charged particle multiplicity at mid-rapidity in Au+Au collisions at sqrt(s_NN) = 200 GeV as a function of the collision centrality. Results on dN/deta(eta<1) divided by the number of participating nucleon pairs, , are presented as a function of . As was found from similar data at sqrt(s_NN) = 130 GeV, the data can be equally well described by parton saturation models and two-component fits which include contributions that scale as Npart and the number of binary collisions, Ncoll. We compare the data at the two energies by means of the ratio R(200/130) of the charged particle multiplicity for the two different energies as a function of . For events with >100$, we find that this ratio is consistent with a constant value of 1.14+-0.01(stat.)+-0.05(syst.).
11 Jul 2003
First-order Fermi acceleration process at a relativistic shock wave is investigated by means of Monte Carlo simulations involving numerical integration of particle equations of motion in a turbulent magnetic field near the shock. In comparison to earlier studies a few 'realistic' features of the magnetic field structure are included. The upstream field consists of a mean field component inclined at some angle to the shock normal and finite-amplitude perturbations imposed upon it. The perturbations are assumed to be static in the local plasma rest frame. We apply an analytic model for the turbulence with a flat or a Kolmogorov spectrum within a finite (wide) wave vector range. The magnetic field is continuous across the shock -- the downstream field structure is derived from the upstream one from the hydrodynamical shock jump conditions. We present and discuss the obtained particle spectra and angular distributions at mildly relativistic sub- and superluminal shocks. We show that particle spectra diverge from a simple power-law, an exact shape of the spectrum depends on both an amplitude of the magnetic field perturbations and the considered wave power spectrum.
The Technical Design for the COMET Phase-I experiment is presented in this paper. COMET is an experiment at J-PARC, Japan, which will search for neutrinoless conversion of muons into electrons in the field of an aluminium nucleus (μe\mu-e conversion, μNeN\mu^- N \to e^- N); a lepton flavor violating process. The experimental sensitivity goal for this process in the Phase-I experiment is 3.1×10153.1\times10^{-15}, or 90 % upper limit of branching ratio of 7×10157\times 10^{-15}, which is a factor of 100 improvement over the existing limit. The expected number of background events is 0.032. To achieve the target sensitivity and background level, the 3.2 kW 8 GeV proton beam from J-PARC will be used. Two types of detectors, CyDet and StrECAL, will be used for detecting the \mue conversion events, and for measuring the beam-related background events in view of the Phase-II experiment, respectively. Results from simulation on signal and background estimations are also described.
Background: Weakly bound and unbound nuclei close to particle drip lines are laboratories of new nuclear structure physics at the extremes of neutron/proton excess. The comprehensive description of these systems requires an open quantum system framework that is capable of treating resonant and nonresonant many-body states on equal footing. Purpose: In this work, we construct the minimal complex-energy configuration interaction approach to describe binding energies and spectra of selected 5 \leq A \leq 11 nuclei. Method: We employ the complex-energy Gamow shell model (GSM) assuming a rigid 4^4He core. The effective Hamiltonian, consisting of a core-nucleon Woods-Saxon potential and a simplified version of the Furutani-Horiuchi-Tamagaki interaction with the mass-dependent scaling, is optimized in the sp space. To diagonalize the Hamiltonian matrix, we employ the Davidson method and the Density Matrix Renormalization Group technique. Results: Our optimized GSM Hamiltonian offers a good reproduction of binding energies and spectra with the root-mean-square (rms) deviation from experiment of 160 keV. Since the model performs well when used to predict known excitations that have not been included in the fit, it can serve as a reliable tool to describe poorly known states. A case in point is our prediction for the pair of unbound mirror nuclei 10^{10}Li-10^{10}N in which a huge Thomas-Ehrman shift dramatically alters the pattern of low-energy excitations. Conclusion: The new model will enable comprehensive studies of structure and reactions aspects of light drip-line nuclei.
We have measured transverse momentum distributions of charged hadrons produced in d+Au collisions at sqrt(s_NN) = 200 GeV. The spectra were obtained for transverse momenta 0.25 < p_T < 6.0 GeV/c, in a pseudorapidity range of 0.2 < eta < 1.4 in the deuteron direction. The evolution of the spectra with collision centrality is presented in comparison to p+pbarcollisions at the same collision energy. With increasing centrality, the yield at high transverse momenta increases more rapidly than the overall particle density, leading to a strong modification of the spectral shape. This change in spectral shape is qualitatively different from observations in Au+Au collisions at the same energy. The results provide important information for discriminating between different models for the suppression of high-p_T hadrons observed in Au+Au collisions.
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