HEP Phenomenology·hep-ph
39 papers—23 primary·16 cross-listed·reconstructed*
We proceed with our study of the Hagen-Hurley equations describing spin one bosons. In this work, we describe a general decay of the Hagen-Hurley boson. It is important that the transformation conserves spin of the decaying boson and provides information about the kinematics of the decay. We explain the high instability of the Hagen-Hurley particle and identify it as the boson.
The correspondence between the gluon density behavior of the color dipole picture and the two-Pomeron approach at low deep inelastic scattering is considered. For photon virtualities of , the results for the parametrization and CDP models are defined by the CDP asymptotic limit and are compatible with the soft and hard-Pomeron approach. These results show that the hard-Pomeron trajectory does not guarantee converging towards the asymptotic representation at low and large () values in a wide range of the virtual-photon-proton energy squared. The gluon distributions can be obtained directly in terms of the proton structure functions and the running coupling and compared with the results from the GJR and MSTW parametrizations.
We present a modification of the DGLAP improved saturation model with respect to the nonlinear correction (NLC). The GLR-MQ improved saturation model is considered by employing the parametrization of proton structure function due to the Laplace transforms method, which preserves its behavior success in the low and high regions. We show that the geometric scaling holds for the GLR-MQ improved model in a wide kinematic region . These results are comparable with other models in a wide kinematic region . The behavior of the dipole cross sections, with respect to the GLR-MQ improved saturation model, are comparable with the Color Glass Condensate (CGC) model. The model describes the dipole cross sections in the inclusive and diffractive processes. We also compare the nonlinear corrections to the impact-parameter dependent saturation (IP-Sat) model with the impact-parameter dependent color glass condensate (b-CGC) dipole model. Finally, we consider the linear and nonlinear corrections to the IP Non-Sat model. These results provide a benchmark for further investigation of QCD at small in future experiments such as the Large Hadron Collider and Future Circular Collider projects.
Entropy or information is a fundamental quantity contained in a system in statistical mechanics and information theory. In this paper, a definition of classical information entropy of parton distribution functions is suggested. The extensive and supper-additive properties of the defined entropy are discussed. The concavity is also deduced for the defined entropy. As an example, the classical information entropy of the gluon distribution of the proton is presented. There are some particular features of the evolution of the information entropy in the saturating domain, which could be used in finding the signals of gluon saturation.
M. U. Ashraf🇵🇰 · Junaid Tariq🇵🇰 · Sumaira Ikram🇵🇰 · A. M. Khan🇨🇳 · Jamilla Butt🇴🇲 · Samya Zain🇺🇸
We report on the excitation function of anti-baryon to baryon ratios (, {\alam /\lam} and {\axi / \xim}) in collisions at {\sqrts} = 0.9, 2.76, 7 TeV from DPMJET-III, Pythia~8, EPOS~1.99, and EPOS-LHC model simulations. To study the predictions of these models at {\sqrts} = 13.6 TeV. The anti-baryon to baryon ratios are extremely important for the study of baryon number transport mechanisms. These ratios help determine the carriers of the baryon number and in the extraction of baryon structure information. Even though all models show a good agreement between model simulations and data, the ratios extracted from DPMJET-III model closely describes data at all energies. It is observed that these ratios converge to unity for various model predictions. This convergence also indicates that the anti-baryon to baryon ratios follow the mass hierarchy, such that the hyperon specie containing more strange quarks ({\alam /\lam} and {\axi / \xim}) approaches unity faster than specie containing fewer strange quarks (). It is also observed that the ratio approaches unity more rapidly with the increase in {\sqrts} energy. At lower energies we observe an excess production of baryons over anti-baryons. However, this effect vanishes at higher energies due to the baryon-anti-baryon pair production and the baryon-anti-baryon yield becomes equal. Using model simulations, we additionally compute the asymmetry, (A\equiv\frac{N_{p}-N_{\bar{p}}}N_{p}+N_{\bar{p}}}) for protons. The asymmetry shows a decreasing trend with increase in energy from 0.9 to 7 TeV for all energies. This asymmetry trend is confirmed by model predictions at {\sqrts} = 13.6 TeV which will help to put possible constraints on model calculations at {\sqrts} = 13.6 TeV once the Run-III data for LHC becomes available.
Anirban Majumdar🇮🇳 · Dimitrios K. Papoulias🇬🇷 · Rahul Srivastava🇮🇳 · José W. F. Valle🇪🇸
Prompted by the recent Dresden-II reactor data we examine its implications for the determination of the weak mixing angle, paying attention to the effect of the quenching function. We also determine the resulting constraints on the unitarity of the neutrino mixing matrix, as well as on the most general type of nonstandard neutral-current neutrino interactions.
M.U. Ashraf🇵🇰 · Junaid Tariq🇵🇰 · Sumaira Ikram🇵🇰 · A. M. Khan🇨🇳
We analyzed the transverse momentum {\ppt} spectra of different particle species containing strange quark {\ks}, {\lam (\alam)} and {\xim ({\axi})} in different centrality intervals at mid-rapidity () from {\auau} collisions at {\sqrtsNN}= 54.4 GeV. The {\ppt} spectra of these strange hadrons are investigated by Tsallis-like distribution. The Tsallis-like distribution satisfactorily fits the experimental data. The effective temperature, entropy based parameter and mean {\ppt} extracted from the Tsallis-like distribution function while the kinetic freeze-out temperature () and transverse flow velocity () are extracted by an alternative method. The effective temperature, entropy based parameter and mean {\ppt} are found to be strongly dependent on centrality. The effective temperature of multi-strange particle ({\xim ({\axi})}) is larger as compared to singly-strange particles {\lam (\alam)} and {\ks}. Furthermore, the extracted parameters from alternative approach decreases from central collisions to peripheral collisions, except the parameter which shows an opposite behaviour. A mass dependent kinetic freeze-out scenario is observed as the effective flow is larger for massive particles than the lighter one. Furthermore, the , and mean {\ppt} () shows decreasing trend as we go from central collisions to peripheral collisions. The entropy parameter increases from central to peripheral collisions.
Toru Kojo🇯🇵 · Daiki Suenaga🇯🇵
Smooth transitions from hadronic matter to hot and dense matter of quantum chromodynamics accompany continuous transformations in effective degrees of freedom. The microscopic descriptions should include relativistic quarks interacting inside of hadrons. In this work we construct a schematic constituent quark model with relativistic kinematics which captures the global trends of meson spectra in the light, strange, and charm quark sectors. We examine the roles of the scalar- and vector-confining potentials as well as semishort range correlations in estimating the strength of central, spin-spin, and spin-orbit interactions. The quark dynamics in low-lying mesons is very sensitive to relativistic kinematics and short range interactions, while in high-lying mesons are sensitive to the composition of scalar- and vector-confinement. After expressing mesons in terms of quark wave functions, we use them to describe the quark occupation probability in a meson resonance gas, and discuss how it can be related to its counterpart in a quark-gluon-plasma.
We consider the interplay between dark matter and leptogenesis in a common framework, where three right-handed neutrinos, one fermionic dark matter and two singlet scalars are introduced into the Standard Model. The mixing of the two singlet scalars not only determine the dark matter relic density but also connect right-handed neutrino with dark matter. We consider that the baryon asymmetry is generated via the resonant leptogenesis and the right-handed neutrino masses are at TeV level. We present a viable parameter space satisfying relic density constraint, and the parameter space is more flexible in the case of a larger mixing angle. We found that the existence of dark matter in the model can not only dilute the baryon asymmetry but can also generate a larger baryon asymmetry due to the process of dark matter annihilation into a pair of right-handed neutrinos even though dark matter mass is lighter than right-handed neutrino mass. The enhanced effect depends on the dark matter mass as well as right-handed neutrino mass , and one still can find a baryon asymmetry enhanced in the case of GeV.
P. Colangelo🇮🇹 · F. De Fazio🇮🇹 · N. Losacco🇮🇹 · F. Loparco🇮🇹 · M. Novoa-Brunet🇮🇹
The hadronic form factors of semileptonic decays to the wave charmonium 4-plet can be expressed near the zero-recoil point in terms of universal functions, performing a systematic expansion in QCD in the relative velocity of the heavy quarks and in . Such functions are independent of the member of the multiplet involved in the transitions. We present the results of an NLO calculation up to classifying the universal functions at this order. We work out a set of relations among the form factors of the same mode and of different modes, which should be reproduced by explicit calculations, reducing the hadronic uncertainty affecting such channels. The approach is also helpful to investigate the debated nature of , studying the production in semileptonic decays and comparing it to the modes involving the other charmonia.
Zhen-Hua Zhang🇨🇳 · Jing-Juan Qi🇨🇳
We introduce a set of observables representing angular distribution asymmetries, which can be viewed as a generalization of the forward-backward asymmetry of angular distributions, and can be used as an effective tool to search for violation in three-body decays of bottom and charmed baryons. We propose to search for such asymmetries (1) in decays with , , or involved, such as and ; and (2) in three-body decays of bottom baryons with opposite parity intermediate resonances involved. Typical examples include , and , in which the last decay channel is used as a toy model to illustrate of the basic idea.
Sergey Koshkarev🇪🇪 · Stefan Groote🇪🇪
Using the GS09 model we predict the possible impact of the parton momentum correlation on the -pair production at the Spin Physics Detector at the Nuclotron-based Ion Collider Facility. The double production and the effective cross sections are calculated.
This paper presents a method for the analysis of process based on the consideration of the angles of expansion of finite pion pairs. The proposed approach makes it possible to effectively carry out selection of events in both neutral and charge-conjugate modes of the decay of . Application of the method for the analysis of similar three-body decays in some cases will simplify the analysis and refine current results.
Wolfgang Lucha🇦🇹 · Dmitri Melikhov🇷🇺 · Hagop Sazdjian🇫🇷
We propose to increase the factual reliability of descriptions of exotic multiquark hadrons utilizing the approach to bound states of strongly interacting constituents known as QCD sum rules, by allowing exclusively all contributions that potentially bear some relevance for multiquark states to enter the correlation functions that form the main ingredient of this framework. The route to this goal is illustrated for the (presumably least involved) special case of tetraquark states.
Z. Hulcher🇺🇸 · D. Pablos🇮🇹 · K. Rajagopal🇺🇸
QGP, a strongly coupled liquid when viewed at length scales of , must reveal quark- and gluon-like quasi-particles when probed with sufficiently high momentum transfer, since QCD is asymptotically free. High energy jet partons traversing the droplet of QGP produced in a heavy ion collision can trigger these high-momentum exchanges with medium constituents and so have the potential to reveal the presence of such quasi-particles, a key step toward the experimental study of the microscopic structure of QGP. We implement this physics within the hybrid strong/weak coupling model which, prior to this work, only accounted for nonperturbative aspects of parton energy loss. Elastic Molière scatterings between partons from a jet shower and medium quasi-particles result in deflection of the propagating jet partons and struck thermal medium partons recoiling at large angles. We discuss the effect of Molière scatterings on some of the most widely used groomed and ungroomed jet substructure observables. Given the large impact on jet observables of the wakes generated by the hydrodynamic response of the QGP fluid as the shower and scattered partons lose energy and momentum to it, as well as the presence of selection biases, finding distinctive signatures of Molière scattering, and hence the presence of quasi-particles in QGP, is a challenge. Toward this end, we emphasize the discovery potential of subjet (jets within jets) distributions.
R. Plantey🇳🇴 · O. M. Ogreid🇳🇴 · P. Osland🇳🇴 · M. N. Rebelo🇵🇹 · M. Aa. Solberg🇳🇴
We study the potential of Weinberg's -symmetric three-Higgs-doublet model (3HDM). The potential is designed to accommodate CP violation in the scalar sector within a gauge theory, while at the same time allowing for natural flavour conservation. This framework allows for both explicit and spontaneous CP violation. CP can be explicitly violated when the coefficients of the potential are taken to be complex. With coefficients chosen to be real, CP can be spontaneously violated via complex vacuum expectation values (vevs). In the absence of the terms leading to the possibility of CP violation, either explicit or induced by complex vevs, the potential has two global U(1) symmetries. In this case, spontaneous symmetry breaking would in general give rise to massless states. In a realistic implementation, those terms must be included, thus preventing the existence of Goldstone bosons. A scan over parameters, imposing the existence of a neutral state at 125 GeV that is nearly CP-even shows that, in the absence of fine-tuning, the scalar spectrum contains one or two states with masses below 125 GeV that have a significant CP-odd component. These light states would have a low production rate via the Bjorken process and could thus have escaped detection at LEP. At the LHC the situation is less clear. While we do not here aim for a full phenomenological study of the light states, we point out that the decay channel would be challenging to measure because of suppressed couplings to .
Sougata Ganguly🇮🇳 · Sourov Roy🇮🇳 · Ananya Tapadar🇮🇳
The lack of information before Big Bang Neucleosynthesis (BBN) allow us to assume the presence of a new species whose energy density redshifts as where and is the scale factor. This non-standard cosmological setup facilitates a larger portal coupling between the dark and the visible sectors even when the two sectors are not in thermal equilibrium. Here, we have considered gauge extension of the Standard Model (SM) and studied different phases of the cosmological evolution of a thermally decoupled dark sector such as leak-in, freeze-in, reannihilation, and late-time annihilation in the presence of fast expansion. Due to the tree level kinetic mixing between and gauge bosons, the dark sector couples with the and flavored leptons of the SM. We show that in our scenario it is possible to reconcile the dark matter relic density and muon anomaly. In particular, we show that for , , , and relic density constraint of dark matter, constraint from muon anomaly, and other cosmological, astrophysical constraints are satisfied.
Eef van Beveren🇵🇹 · George Rupp🇵🇹
Threshold enhancements predicted by the Resonance-Spectrum-Expansion (RSE) production amplitude and observed by the BaBaR Collaboration in open-bottom production above the threshold, as well as by several collaborations in open-charm production above the threshold, can also be seen in diphoton amplitudes at energies above 100 GeV. One such threshold effect is visible in tau-tau and muon-muon data of the L3 Collaboration at LEP, and in the diphoton and four-lepton data of the ATLAS and CMS Collaborations at LHC, as it is enhanced by the nearby presence of the Higgs resonance. This supports the assumption of pair production at about 115 GeV. An accumulation of single-photon and dimuon data around 28 GeV observed by the L3 and the CMS Collaborations, respectively, lend further credit to the hypothesis of the existence of a (pseudo)scalar boson with a mass of about 57 GeV.
This work incorporates the effect of short-range repulsion between particles into the Cooper-Frye hadron sampling procedure. This is achieved by means of a rejection sampling step, which prohibits any pair of particles from overlapping in the coordinate space, effectively modeling the effect of hard-core repulsion. The new procedure -- called the FIST sampler -- is based on the package Thermal-FIST. It is used here to study the effect of excluded volume on cumulants of the (net-)proton number distribution in central collisions of heavy ions in a broad collision energy range in conjunction with exact global conservation of baryon number, electric charge, and strangeness. The results are compared with earlier calculations based on analytical approximations, quantifying the accuracy of the latter at different collision energies. An additional advantage of the new method over the analytic approaches is that it offers the flexibility provided by event generators, making it straightforwardly extendable to other observables.
Shehu AbdusSalam🇮🇷 · Leila Kalhor🇮🇷 · Mohammad Mohammadidoust🇮🇷
We made global fits of the inert Higgs doublet model (IDM) in the light of collider and dark matter search limits and the requirement for a strongly first-order electroweak phase transition (EWPT). These show that there are still IDM parameter spaces compatible with the observational constraints considered. In particular, the data and theoretical requirements imposed favour the hypothesis for the existence of a scalar dark matter candidate around 100 GeV. This is mostly due to the pull towards lower masses by the EWPT constraint. The impact of electroweak precision measurements, the dark matter direct detection limits, and the condition for obtaining a strongly enough first-order EWPT, all have strong dependence, sometimes in opposing directions, on the mass splittings between the IDM scalars.
Lohan Sartore🇫🇷 · Markos Maniatis🇨🇱 · Ingo Schienbein🇫🇷 · Bjoern Herrmann🇫🇷
In the general Two-Higgs Doublet Model it has been shown that the Higgs potential can be expressed in terms of gauge-independent quantities. In particular, stability, electroweak symmetry breaking, and CP symmetry can be understood in a concise way, avoiding unphysical gauge degrees of freedom. We complete this program and show how all the masses, the trilinear and quartic scalar interactions, the gauge-boson-Higgs interactions, as well as the Yukawa couplings in the general THDM can be expressed in a gauge-invariant way.
Subhajit Ghosh🇺🇸 · Triparno Bandyopadhyay🇮🇳 · Tuhin S. Roy🇮🇳
In addition to giving rise to spectacular new physics signals in the final states of meson decays, Axion-like-particles also induce modifications in the standard model decays of mesons. These `indirect' signatures can be parametrized as the modifications of the hadronic form factors and can be probed using meson decay width and decay distribution measurements. Starting with a generalized ALP Lagrangian, we demonstrate these effects for semileptonic Kaon decays and derived bounds using NA48/2 data. We also briefly discuss other indirect signatures such as modification of meson mass spectrum and `sum rules' comprised of meson decay amplitudes which show deviation in presence of ALP.
Andrei Angelescu🇩🇪 · Andreas Bally🇩🇪 · Florian Goertz🇩🇪 · Sascha Weber🇩🇪
Gauge-Higgs grand unification theories are models of gauge-Higgs unification that extend the electroweak group into a simple group that includes the color symmetry. The minimal option is a gauge-Higgs grand unification based on the SU(6) gauge group, mirroring SU(5) grand unification in 4D while providing a solution to the hierarchy problem. We explore different minimal and realistic novel incarnations of SU(6) gauge-Higgs grand unification. We submit the setup to the various flavor hierarchies observed in nature and, utilizing the power of the fifth dimension, identify an embedding that provides a compelling model of quarks and leptons that naturally explains the mass hierarchies and the CKM/PMNS structure. We perform a detailed study of quark - and lepton - flavor constraints (which are intimately related due to the GUT nature) together with an analysis of the Higgs potential which arises at the loop level. Electroweak precision constraints on the model are discussed and the rich scalar sector is analyzed. Future flavor constraints from upcoming experiments will provide a stringent test for this class of models, while a scalar singlet and leptoquark provide unique targets for current and future collider experiments to probe this solution to various open questions in nature.
Patrick Copinger🇹🇼 · Koichi Hattori🇨🇳 · Di-Lun Yang🇹🇼
Augmentations to the Euler-Heisenberg Lagrangian (QED one-loop effective action in homogeneous electromagnetic fields) under a constant background axial gauge are examined. Two special configurations admit an exact eigendecomposition, and hence effective action as a spectral sum, of the augmented Dirac operator: one with a magnetic field with chiral chemical potential, and the other with an electric field with spatial axial gauge, which resembles an emergent vorticity. An enhancement to Schwinger pair production is found for the latter, which is more fully analyzed using the worldline instanton formalism. There it is found the overall enhancement is due to the spatial axial gauge serving as a negative mass shift. Finally, we remark on the exactly solvable massless case for arbitrary electromagnetic and axial gauges.
Tristan L. Smith🇺🇸 · Vivian Poulin🇫🇷 · Théo Simon🇫🇷
The Hubble tension can be addressed by modifying the sound horizon () before recombination, triggering interest in -free early-universe estimates of the Hubble constant, . Constraints on from an -free analysis of the full shape BOSS galaxy power spectra within LCDM were recently reported and used to comment on the viability of physics beyond LCDM. Here we demonstrate that -free analyses with current data depend on the model and the priors placed on the cosmological parameters, such that LCDM analyses cannot be used as evidence for or against new physics. We find that beyond-LCDM models which introduce additional energy density with significant pressure support, such as early dark energy (EDE) or additional neutrino energy density (), lead to larger values of . On the other hand, models which only affect the time of recombination, such as a varying electron mass (), produce constraints similar to LCDM. Using BOSS data, constraints from light element abundances, cosmic microwave background (CMB) lensing, a CMB-based prior on the scalar amplitude (), spectral index (), and from the Pantheon+ supernovae data set, we find that in LCDM, km/s/Mpc; EDE, ; , ; , . Using a prior on from uncalibrated BAO and CMB measurements of the projected sound horizon, these values become in LCDM, ; EDE, ; , ; , . With current data, none of the models are in significant tension with SH0ES, and consistency tests based on comparing posteriors with and without marginalization are inconclusive with respect to the viability of beyond LCDM models.
Emel Altas🇹🇷 · Bayram Tekin🇹🇷
We provide two novel ways to compute the surface gravity () and the Hawking temperature of a stationary black hole: in the first method is given as the three-volume integral of the Gauss-Bonnet invariant (or the Kretschmann scalar for Ricci-flat metrics) in the total region outside the event horizon; in the second method it is given as the surface integral of the Riemann tensor contracted with the covariant derivative of a Killing vector on the event horizon. To arrive at these new formulas for the black hole temperature (and the related surface gravity), we first construct a new differential geometric identity using the Bianchi identity and an antisymmetric rank- tensor, valid for spacetimes with at least one Killing vector field. The Gauss-Bonnet tensor and the Gauss-Bonnet scalar play a particular role in this geometric identity. We calculate the surface gravity and the Hawking temperature of the Kerr and the extremal Reissner-Nordström holes as examples.
Zohreh Davoudi🇺🇸 · Niklas Mueller🇺🇸 · Connor Powers🇺🇸
The phase diagram of strong interactions in nature at finite temperature and chemical potential remains largely unexplored theoretically due to inadequacy of Monte-Carlo-based computational techniques in overcoming a sign problem. Quantum computing offers a sign-problem-free approach but evaluating thermal expectation values is generally resource intensive on quantum computers. To facilitate thermodynamic studies of gauge theories, we propose a generalization of thermal-pure-quantum-state formulation of statistical mechanics applied to constrained gauge-theory dynamics, and numerically demonstrate that the phase diagram of a simple low-dimensional gauge theory is robustly determined using this approach, including mapping a chiral phase transition in the model at finite temperature and chemical potential. Quantum algorithms, resource requirements, and algorithmic and hardware error analysis are further discussed to motivate future implementations. Thermal pure quantum states, therefore, may present a suitable candidate for efficient thermal-state preparation in gauge theories in the era of quantum computing.
Belle II collaboration: I. Adachi · L. Aggarwal · H. Ahmed · H. Aihara · N. Akopov · A. Aloisio · N. Anh Ky · T. Aushev · V. Aushev · H. Bae · P. Bambade · Sw. Banerjee and 338 other authors
We study the processes ( = 0, 1, or 2) using samples at center-of-mass energies = 10.701, 10.745, and 10.805 GeV, corresponding to 1.6, 9.8, and 4.7 fb of integrated luminosity, respectively. These data were collected with the Belle II detector during special operations of the SuperKEKB collider above the resonance. We report the first observation of signals at = 10.745 GeV. By combining Belle II data with Belle results at = 10.867 GeV, we find energy dependencies of the Born cross sections for to be consistent with the shape of the state. These data indicate that the internal structures of the and states may differ. Including data at = 10.653 GeV, we also search for the bottomonium equivalent of the state decaying into . No significant signal is observed for masses between 10.45 and 10.65 GeV/.
Carlos Henrique de Lima🇨🇦 · Alberto Tonero🇨🇦 · Andres Vasquez🇧🇪 · Rogerio Rosenfeld🇧🇷
The calculation of P-wave Sommerfeld enhancement in processes with unstable particles in the final state is known to be divergent. In a complete description, where resonant (on-shell unstable particles) and non-resonant contributions are included, it has been shown that results are finite. For most beyond the Standard Model applications, these complete calculations are not readily available. In this work, we are interested in the near-threshold region and we consider only the resonant contribution. In this case, we provide a simplified prescription to compute the P-wave Sommerfeld enhancement in the narrow-width approximation of the unstable particle that directly eliminates divergences. We show that we can define a finite resonant contribution without the inclusion of the non-resonant processes in a way similar to the usual S-wave Sommerfeld enhancement.
Mengxue Zhang🇨🇳 · Yang He🇨🇳 · Shanshan Cao🇨🇳 · Li Yi🇨🇳
Jet quenching has successfully served as a hard probe to study the properties of Quark-Gluon Plasma (QGP). As a multi-particle system, jets take time to develop from a highly virtual parton to a group of partons close to mass shells. In this study, we present a systematical study on the effects of this formation time on jet quenching in relativistic nuclear collisions. Jets from initial hard scatterings were simulated with Pythia, and their interactions with QGP were described using a Linear Boltzmann Transport (LBT) model that incorporates both elastic and inelastic scatterings between jet partons and the thermal medium. Three different estimations of the jet formation time were implemented and compared, including instantaneous formation, formation from single splitting, and formation from sequential splittings, before which no jet-medium interaction was assumed. We found that deferring the jet-medium interaction with a longer formation time not only affects the overall magnitude of the nuclear modification factor of jets, but also its dependence on the jet transverse momentum.
Santosh K. Das🇮🇳 · Prabhakar Palni🇮🇳 · Jhuma Sannigrahi🇮🇳 · Jan-e Alam🇮🇳 · Cho Win Aung🇮🇳 · Yoshini Bailung🇮🇳 · Debjani Banerjee🇮🇳 · Gergely Gábor Barnaföldi🇭🇺 · Subash Chandra Behera🇮🇳 · Partha Pratim Bhaduri🇮🇳 · Samapan Bhadury🇮🇳 · Rajesh Biswas🇮🇳 and 55 other authors
The discovery and characterization of hot and dense QCD matter, known as Quark Gluon Plasma (QGP), remains the most international collaborative effort and synergy between theorists and experimentalists in modern nuclear physics to date. The experimentalists around the world not only collect an unprecedented amount of data in heavy-ion collisions, at Relativistic Heavy Ion Collider (RHIC), at Brookhaven National Laboratory (BNL) in New York, USA, and the Large Hadron Collider (LHC), at CERN in Geneva, Switzerland but also analyze these data to unravel the mystery of this new phase of matter that filled a few microseconds old universe, just after the Big Bang. In the meantime, advancements in theoretical works and computing capability extend our wisdom about the hot-dense QCD matter and its dynamics through mathematical equations. The exchange of ideas between experimentalists and theoreticians is crucial for the progress of our knowledge. The motivation of this first conference named "HOT QCD Matter 2022" is to bring the community together to have a discourse on this topic. In this article, there are 36 sections discussing various topics in the field of relativistic heavy-ion collisions and related phenomena that cover a snapshot of the current experimental observations and theoretical progress. This article begins with the theoretical overview of relativistic spin-hydrodynamics in the presence of the external magnetic field, followed by the Lattice QCD results on heavy quarks in QGP, and finally, it ends with an overview of experiment results.
Haowei Shi🇺🇸 · Quntao Zhuang🇺🇸
The nature of dark matter is unknown and calls for a systematical search. For axion dark matter, such a search relies on finding feeble random noise arising from the weak coupling between dark matter and microwave haloscopes. We model such process as a quantum channel and derive the fundamental precision limit of noise sensing. An entanglement-assisted strategy based on two-mode squeezed vacuum is thereby demonstrated optimal, while the optimality of a single-mode squeezed vacuum is found limited to the lossless case. We propose a `nulling' measurement (squeezing and photon counting) to achieve the optimal performances. In terms of the scan rate, even with 20-decibel of strength, single-mode squeezing still underperforms the vacuum limit which is achieved by photon counting on vacuum input; while the two-mode squeezed vacuum provides large and close-to-optimum advantage over the vacuum limit, thus more exotic quantum resources are no longer required. Our results highlight the necessity of entanglement assistance and microwave photon counting in dark matter search.
We compute the contribution to the anomalous dimension of the twist-2 operators in N=4 SYM theory, which is proportional to the number of fermion loops inside Feynman diagrams or, formally, to the number of fermions. The result was obtained by the method based on the calculation of critical indices at the critical point by analogy with previous similar computations in scalar theories and in QCD. The obtained result is much simpler with compare to analogous results in QCD and almost satisfies the maximal transcedentality principle. A possible relation between the obtained result and integrability is discussed.
Archana Radhakrishnan🇺🇸 · Jozef Dudek🇺🇸 · Robert Edwards🇺🇸
We present the first calculation in lattice QCD of the process in which the narrow vector resonance appears. Using a lattice on which the pion has a mass of 284 MeV, we determine the transition amplitude at 128 points in the plane, and find suitable resonant scattering descriptions. We demonstrate the need to account for --wave elastic scattering when converting the finite-volume matrix elements computed in lattice QCD to the physically relevant infinite-volume matrix elements, even when we are primarily interested in the --wave amplitude. Analytically continuing parameterizations of the amplitude to the resonance pole, we obtain the transition form-factor, and compare the value to the corresponding value extracted from the experimental partial-decay width.
Zhehan Qin🇨🇳 · Zhong-Zhi Xianyu🇨🇳
Massive spinning particles acquire helicity-dependent chemical potentials during the inflation from axion-type couplings. Such spinning fields can mediate sizable inflaton correlators which we call the helical inflation correlators. Helical inflaton correlators are approximately scale invariant, dS boost breaking, parity-violating, and are promising observables of cosmological collider physics. In this work, we present complete and analytical results for 4-point helical inflation correlators with tree-level exchanges of massive spinning particles, including both the smooth background and the oscillatory signals. We compute the bulk Schwinger-Keldysh integrals in two independent ways, including the partial Mellin-Barnes representation and solving bootstrap equations. We also present new closed-form analytical results for 3-point functions with massive scalar or helical spinning exchanges. The analytical results allow us to concretely and efficiently explore the phenomenological consequences of helicity-dependent chemical potentials. In particular, we show that the chemical potential can exponentially enhance oscillatory signals of both local and nonlocal types, but only affects the background in a rather mild way. Our results extend the de Sitter bootstrap program to include nonperturbative breaking of de Sitter boosts. Our results also explicitly verify the recently proposed cutting rule for cosmological collider signals.
José Luis Bernal🇺🇸 · Andrea Caputo🇮🇱 · Gabriela Sato-Polito🇺🇸 · Jordan Mirocha🇨🇦 · Marc Kamionkowski🇺🇸
The flux of high-energy astrophysical rays is attenuated by the production of electron-positron pairs from scattering off of extragalactic background light (EBL). We use the most up-to-date information on galaxy populations to compute their contributions to the pair-production optical depth. We find that the optical depth inferred from -ray measurements exceeds that expected from galaxies at the level. If the excess is modeled as a frequency-independent re-scaling of the standard contribution to the EBL from galaxies, then an excess (an overall increase of the EBL) over the null hypothesis of no excess at the level. If the frequency dependence of the excess is instead modeled as a two-photon decay of a dark-matter axion, then the excess is favored over the null hypothesis at the confidence level. While we find no evidence for a dark-matter signal, the analysis sets the strongest current bounds on the photon-axion coupling over the eV mass range. This work highlights the sensitivity of -ray optical depth measurements to ALPs, which is expected to improve with new observatories and better EBL determinations from future observations.
Gemma Zhang · Siddharth Mishra-Sharma🇺🇸 · Cora Dvorkin🇺🇸
Strong gravitational lensing has emerged as a promising approach for probing dark matter models on sub-galactic scales. Recent work has proposed the subhalo effective density slope as a more reliable observable than the commonly used subhalo mass function. The subhalo effective density slope is a measurement independent of assumptions about the underlying density profile and can be inferred for individual subhalos through traditional sampling methods. To go beyond individual subhalo measurements, we leverage recent advances in machine learning and introduce a neural likelihood-ratio estimator to infer an effective density slope for populations of subhalos. We demonstrate that our method is capable of harnessing the statistical power of multiple subhalos (within and across multiple images) to distinguish between characteristics of different subhalo populations. The computational efficiency warranted by the neural likelihood-ratio estimator over traditional sampling enables statistical studies of dark matter perturbers and is particularly useful as we expect an influx of strong lensing systems from upcoming surveys.
Steven Abel🇬🇧 · Andrei Constantin🇬🇧 · Thomas R. Harvey🇬🇧 · Andre Lukas🇬🇧
Large classes of standard single-field slow-roll inflationary models consistent with the required number of e-folds, the current bounds on the spectral index of scalar perturbations, the tensor-to-scalar ratio, and the scale of inflation can be efficiently constructed using genetic algorithms. The setup is modular and can be easily adapted to include further phenomenological constraints. A semi-comprehensive search for sextic polynomial potentials results in roughly O(300,000) viable models for inflation. The analysis of this dataset reveals a preference for models with a tensor-to-scalar ratio in the range 0.0001 < r < 0.0004. We also consider potentials that involve cosine and exponential terms. In the last part we explore more complex methods of search relying on reinforcement learning and genetic programming. While reinforcement learning proves more difficult to use in this context, the genetic programming approach has the potential to uncover a multitude of viable inflationary models with new functional forms.
N. Ahmadiniaz🇩🇪 · T.E. Cowan🇩🇪 · J. Grenzer🇩🇪 · S. Franchino-Viñas🇩🇪 · A. Laso Garcia🇩🇪 · M. Šmíd🇩🇪 · T. Toncian🇩🇪 · M.A. Trejo🇩🇪 · R. Schützhold🇩🇪
Motivated by recent experimental initiatives, such as at the Helmholtz International Beamline for Extreme Fields (HIBEF) at the European X-ray Free Electron Laser (XFEL), we calculate the birefringent scattering of x-rays at the combined field of two optical (or near-optical) lasers and compare various scenarios. In order to facilitate an experimental detection of quantum vacuum diffraction and birefringence, special emphasis is placed on scenarios where the difference between the initial and final x-ray photons is maximized. Apart from their polarization, these signal and background photons may differ in propagation direction (corresponding to scattering angles in the mrad regime) and possibly energy.
* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.