The analysis of current ultrahigh energy data for hadronic total cross sections and diffractive scattering cross sections points to a steady growth of the optical density with energy for elastic scattering amplitudes in the impact parameter space, $b$. At LHC energy the profile function of the $pp$-scattering amplitude, $T(b)$, reaches the black disk limit at small $b$. Two scenarios are possible at larger energies, $\sqrt{s}\ga 100$ TeV. First, the profile function gets frozen in the black disk limit, $T(b)\simeq 1$ while the radius of the black disk $R_{black\;disk}$ is increasing with $\sqrt s$, providing $σ_{tot}\sim \ln^2s$, $σ_{el}\sim \ln^2s$, $σ_{inel}\sim \ln^2s$. In another scenario the profile function continues to grow at $\sqrt{s}\ga 100$ TeV approaching the maximal value, $T(b)\simeq 2$, that means the resonant disk mode. We discuss features of the resonant disk mode when the disk radius, $R_{resonant\;disk}\,$, increases providing the growth of the total and elastic cross sections $σ_{tot}\sim \ln^2s$, $σ_{el}\sim \ln^2s$, but a more slow increase of inelastic cross section, $σ_{inel}\sim \ln s$.
Using the pre-LHC and LHC data for $πp$ and $pp$ diffractive collisions we study the ultrahigh energy asymptotic regime in the framework of the black disk picture. The black disk picture, being constrained by the s-channel unitarity condition and the $t$-channel analyticity, gives rather definite predictions for diffractive processes increasing with the energy. To deal with the data, we consider the Dakhno-Nikonov eikonal model which predicts a growth of the $\ln^2s$ type for total and elastic cross sections and $(τ={\bf q}_\perp^2\ln^2s)$-scaling for diffractive scattering and diffractive dis…
Diffractive production is considered in the ultrahigh energy region where pomeron exchange amplitudes are transformed into black disk ones due to rescattering corrections. The corresponding corrections in hadron reactions $h_1+h_3\to h_1+h_2+h_3$ with small momenta transferred ($q^2_{1\to 1}\sim m^2/\ln^2s$, $q^2_{3\to 3}\sim m^2/\ln^2s$) are calculated in terms of the $K$-matrix technique modified for ultrahigh energies. Small values of the momenta transferred are crucial for introducing equations for amplitudes. The three-body equation for hadron diffractive production reaction $h_1+h_3\to h…
On the basis of requirements of unitarity and analyticity we analyze the real and imaginary parts of the $pp^\pm$ scattering amplitudes at recent ultrahigh energies, 1-100 TeV. The predictions for the region $\sqrt s > 100$ TeV and ${\bf q}^2<0.4$ GeV$^2$ are given supposing the black disk asymptotic regime. It turns out that the real part of the amplitude is concentrated in the impact parameter space at the border of the black disk. The interplay of hadron and Coulomb interactions is discussed in terms of the $K$-matrix function. The $pp$ diffractive scattering cross section at 7 TeV is calcu…
Central production of lepton-lepton pairs ($e^+e^-$ and $μ^+μ^-$) and heavy quark composite states (charmonia and bottomonia) in diffractive proton collisions (proton momenta transferred ${|\bf q_\perp}|\sim m/\ln s$) are studied at ultrahigh energies ($\ln{s}>>1$), where $σ_{tot}(pp^\pm)\sim\ln^N s$ with $1\la N\la 2$. The $pp^\pm$-rescattering corrections, which are not small, are calculated in terms of the $K$-matrix approach modified for ultrahigh energies. Two versions of hadron interactions are considered in detail: the growth (i) $σ_{tot}(pp^\pm)\sim\ln^2 s$, $σ_{inel}(pp^\pm)\sim\ln^2 …
We study the interplay of hadronic and Coulomb interactions for $pp$ scattering at LHC energies on the basis of the previous determination of the real part of the amplitude [{\it V.V. Anisovich, V.A. Nikonov, J. Nyiri}, Int. J. Mod. Phys. A{\bf 30}, 1550188 (2015)]. The interference of hadron and Coulomb interactions is discussed in terms of the $K$-matrix function technique. Supposing the black disk mode for the asymptotic interaction of hadrons, we calculate interference effects for the energies right up to $\sqrt{s}= 10^6$ TeV. It turns out that the real part of the amplitude is concentrate…
We demonstrate that the shower-to-shower fluctuations of the muon content of extensive air showers correlate with the fluctuations of a variable of the first interaction of Ultra High Energy Cosmic Rays, which is computed from the fraction of energy carried by the hadrons that sustain the hadronic cascade. The influence of subsequent stages of the shower development is found to play a sub-dominant role. As a consequence, the shower-to-shower distribution of the muon content is a direct probe of the hadron energy spectrum of interactions beyond 100 TeV center of mass energies.
Newborn, strongly magnetized neutron stars (so-called magnetars) surrounded by their stellar or merger ejecta are expected to be sources of ultrahigh-energy neutrinos via decay of mesons produced in hadronic interactions of protons which are accelerated to ultrahigh energies by magnetic dissipation of the spindown energy. We show that not only pions and kaons but also charm hadrons, which are typically neglected due to their small production cross sections, can represent dominant contributions to neutrino fluence at ultrahigh energies, because of their short lifetimes, while the ultrahigh-ener…
Charmed mesons may be produced when a primary cosmic ray or the leading hadron in an air shower collide with an atmospheric nucleon. At energies \ge 10^8 GeV their decay length becomes larger than 10 km, which implies that they tend to interact in the air instead of decaying. We study the collisions of long-lived charmed hadrons in the atmosphere. We show that (Λ_c,D)-proton diffractive processes and partonic collisions of any q^2 where the charm quark is an spectator have lower inelasticity than (p,π)-proton collisions. In particular, we find that a D meson deposits in each interaction just a…
This is a written version of a series of lectures aimed at graduate students in astrophysics/particle theory/particle experiment. In the first part, we explain the important progress made in recent years towards understanding the experimental data on cosmic rays with energies > 10^8 GeV. We begin with a brief survey of the available data, including a description of the energy spectrum, mass composition, and arrival directions. At this point we also give a short overview of experimental techniques. After that, we introduce the fundamentals of acceleration and propagation in order to discuss the…
The number of ultrahigh energy events at IceCube is estimated, for the first time, taking into account non-linear QCD effects in the neutrino - hadron cross section. We assume that the extragalactic neutrino flux is given by $Φ_ν(E_ν)=Φ_{0}E^{-2}_ν$ and estimate the neutrino - hadron cross section using the dipole approach and a phenomenological model for the dipole - hadron cross section based on non-linear QCD dynamics. We demonstrate that the non-linear prediction is able to describe the current IceCube data and that the magnitude of the non-linear effects is larger than 20 % for visible en…
The Pierre Auger Collaboration has reported an excess in the number of muons of a few tens of percent over expectations computed using extrapolation of hadronic interaction models tuned to accommodate LHC data. Very recently, we proposed an explanation for the muon excess assuming the formation of a deconfined quark matter (fireball) state in central collisions of ultrarelativistic cosmic rays with air nuclei. At the first stage of its evolution the fireball contains gluons as well as $u$ and $d$ quarks. The very high baryochemical potential inhibits gluons from fragmenting into $u \bar u$ and…
We present a method to compute off-shell effects for processes involving resonant particles at hadron colliders with the possibility to include realistic cuts on the decay products. The method is based on an effective theory approach to unstable particle production and, as an example, is applied to t-channel single top production at the LHC.
We investigate the observed muon deficit in air shower simulations when compared to ultrahigh-energy cosmic ray (UHECR) data. Based upon the observed enhancement of strangeness production in high-energy hadronic collisions reported by the ALICE Collaboration, the concomitant $π\leftrightarrow K$ swap is considered as the keystone to resolve the muon anomaly through its corresponding impact on the shower development. We construct a toy model in terms of the $π\leftrightarrow K$ swapping probability $F_s$. We present a parametrization of $F_s$ in terms of the pseudorapidity that can accommodate …
We present a complete next to next to leading order QCD corrections to the resonant sneutrino and charged slepton production cross sections at hadronic colliders such as the Tevatron and the Large Hadron Collider within the context of $R$-parity violating supersymmetric model. We have demonstrated the role of these corrections in reducing uncertainties resulting from renormalisation and factorisation scales and thereby making our predictions reliable. We have incorporated soft gluon effects at $N^3LO$ level in order to study the stability of our results under perturbation. The NNLO corrections…
Resonant production of diquarks at high energy pp, ep and e+e- colliders
研究了第一代标量和矢量双夸克在高能强子-强子（pp）、轻子-强子（ep）和轻子-轻子（e+e-）对撞机上的共振产生。考虑到光子的强子成分，双夸克可以在轻子-强子和轻子-轻子碰撞中共振产生。本文用SU（3）_{C} x SU（2）_{W} x U（1）_{Y}不变量的广义有效拉格朗日量讨论了双夸克的产生率、衰变宽度和签名。在感兴趣的不变质量区域中检查相应的双射流背景。给出了强子碰撞和分辨光子过程中产生的双夸克的质量极限和耦合。结果表明，当夸克-双夸克-夸克耦合alpha_{DQ} =0.1时，质心能量sqrt（s）=14 TeV的强子对撞机将能发现质量高达m_{DQ} =9 TeV的标量和矢量双夸克.相对而言，在更清晰的环境中，更轻的双夸克态可以在ep和e+e碰撞中探测到.
Many newly discovered excited states are interpreted as bound states of hadrons. Can these hadrons also form resonant states? In this paper, we extend the complex scaling method (CSM) to calculate the bound state and resonant state consistently for the $Λ_c D(\bar D)$ and $Λ_c Λ_c (\bar Λ_c)$ systems. For these systems, the $π, η, ρ$ meson exchange contributions are suppressed, the contributions of intermediate- and short-range forces from $σ/ω$ exchange are dominant. Our results indicate that $Λ_c D$ system can not form bound state and resonant state. There exist resonant states in a wide ran…
We study the lepton-induced resonant production of color-adjoint leptons (leptogluons) at the LHC employing the lepton parton density function of the proton. We demonstrate that this production mechanism can be useful to extend the LHC ability to search for leptogluons beyond purely quark/gluon initiated production processes up to ~ 3.5 TeV leptogluon masses and O(1) TeV compositeness scales. Discerning leptogluons from scalar and vector leptoquarks is also possible in this channel, given a data sample containing the order of 100 signal events. We argue that the resonant channel can be combine…
We have developed a Monte Carlo event generator for non-resonant diphoton ($γγ$) production at hadron collisions in the framework of GR@PPA, which consistently includes additional one-jet production. The jet-matching method developed for initial-state jet production has been extended to the final state in order to regularize the final-state QED divergence in the $qg \rightarrow γγ+ q$ process. A QCD/QED-mixed parton shower (PS) has been developed to complete the matching. The PS has the capability of enforcing hard-photon radiation, and small-$Q^{2}$ photon radiations that are not covered by t…
We have investigated the resonant production of a stop at the Large Hadron Collider, driven by baryon number violating interactions in supersymmetry. We work in the framework of minimal supergravity models with the lightest neutralino being the lightest supersymmetric particle which decays within the detector. We look at various dilepton and trilepton final states, with or without b-tags. A detailed background simulation is performed, and all possible decay modes of the lighter stop are taken into account. We find that higher stop masses are sometimes easier to probe, through the decay of the …
Comparative analysis of the interplay of hadron and Coulomb interactions in $pp^\pm$ scattering amplitudes is performed in a broad energy interval, $\sqrt{s}=1-10^6$ TeV, for two extreme cases: for the asymptotic interactions of hadrons in black disk and resonant disk modes. The interactions are discussed in terms of the $K$-matrix function technique. In the asymptotic regime the real part of the hadronic amplitude is concentrated in both cases on the boundary of the disks in the impact parameter space but the LHC energy region is not asymptotic for the resonant disk mode that lead to a specif…
The high parton density present at high energies and large nuclei is expected to modify the lepton - hadron cross section and the associated observables. In this paper we analyse the impact of the high density effects in the average inelasticity and the neutrino - nucleus cross section at ultra high energies. We compare the predictions associated to the linear DGLAP dynamics with those from the Color Glass Condensate formalism, which includes non-linear effects. Our results demonstrated that the non-linear effects reduce the average inelasticity and that the predictions of the distinct approac…
A hard $γ$-ray spectrum of supernova remnant G106.3+2.7 can be explained by using the hadronic model with the gluon condensation effect. This implies that not only PeVatrons but also EeVatrons generally exist in the universe including our galaxy, and they can accelerate protons to beyond "ankle" ($10^{19}~eV$). Although these proton beams are very weak in the galaxy and cannot be observed individually on the earth, the gluon condensation effect may greatly enhance the proton-proton cross section, which can compensate for the weak proton flux and produce the observed $γ$-rays. We also show that…
We have developed a Monte Carlo event generator for non-resonant diphoton ($γγ$) production at hadron collisions in the framework of GR@PPA, which consistently includes processes having additional one jet radiation. The possible double count problem in the generation of radiative processes is avoided by using the LLL subtraction method that we have applied to the weak-boson production processes. The subtraction method has been extended to the final-state QED divergence that appears in the $qg \rightarrow γγ+ q$ process. Because a parton shower (PS) which regularizes the subtracted QED divergen…
We explore particle physics beyond accelerator energies, motivated by questions exposed in astroparticle physics observations: 1) Are there reasonable modifications to the standard extrapolations of LHC-tuned hadronic interaction models, so that ultrahigh energy cosmic ray (UHECR) showers are well-described with a purely protonic primary composition rather than requiring a tuned, energy-dependent composition mixture as needed in conventional models? 2) What modifications to standard models can solve the deficiency in the predicted ground signal found in hybrid UHECR observations? We find that …
An event generator for diphoton ($γγ$) production in hadron collisions that includes associated jet production up to two jets has been developed using a subtraction method based on the LLL subtraction. The parton shower (PS) simulation to restore the subtracted divergent components involves both QED and QCD radiation, and QED radiation at very small $Q^{2}$ are simulated by referring to a fragmentation function (FF). The PS/FF simulation has the ability to enforce the radiation of a given number of energetic photons. The generated events can be fed to PYTHIA to obtain particle (hadron)-level e…
We use top quark pair production as a probe of top-philic non-resonant new physics. Following a low energy effective field theory approach, we calculate several key observables in top quark pair production at hadron colliders (e.g., total cross section, ttbar invariant mass distribution, forward-backward asymmetry, spin correlations) including the interference of the Standard Model with dimension-six operators. We determine the LHC reach in probing new physics after having taken into account the Tevatron constraints. In particular, we show that the gluon fusion process gg -> ttbar which remain…
Energetics of the ultrahigh-energy cosmic rays (UHECRs) generated in the universe is crucial for pinning down their candidate sources. Using the recent Auger data on UHECR spectra, we calculate the UHECR energy generation rate density for different species of nuclei at the injection, considering intermediate and heavy nuclei as well as protons, through scanning over source parameters on the spectral index, maximum energy and redshift evolution. We find the resulting UHECR energy generation rate density to be $\approx(0.2-2)\times$10$^{44}$~erg~Mpc$^{-3}$~yr$^{-1}$ at $10^{19.5}$~eV with a nont…
Measurements of proton and nuclear collisions at the Large Hadron Collider at nucleon-nucleon c.m. energies up to $\sqrt{s_{NN}}=$ 13 TeV, have improved our understanding of hadronic interactions at the highest energies reached in collisions of cosmic rays with nuclei in the earth atmosphere, up to $\sqrt{s_{NN}}\approx 450$ TeV. The Monte Carlo event generators (EPOS, QGSJET, and SIBYLL) commonly used to describe the air showers generated by ultrahigh-energy cosmic rays (UHECR, with $E_{CR}\approx 10^{17}$--$10^{20}$ eV) feature now, after parameter retuning based on LHC Run-I data, more cons…
Resonant production of leptogluons at the FCC based ep and \mup colliders have been analyzed. It is shown that e-FCC and μ-FCC will cover much wider region of e_{8} and μ_{8} masses than the LHC. While leptogluons with appropriate masses (if exist) will be discovered earlier by the FCC pp collider, lepton-proton colliders will give opportunity to handle very important additional information. For example, compositeness scale can be probed up to multi-hundred TeV region.
In order to estimate the possibility to observe exotic physics in a neutrino telescope, it is essential to first understand the flux of atmospheric neutrinos, muons and dimuons. We study the production of these leptons by high-energy cosmic rays. We identify three main sources of muons of energy E > 10^6 GeV: the weak decay of charm and bottom mesons and the electromagnetic decay of unflavored mesons. Contrary to the standard assumption, we find that eta mesons, not the prompt decay of charm hadrons, are the dominant source of atmospheric muons at these energies. We show that, as a consequence…
Motivated by Pierre Auger Observatory results favoring a heavy nuclear composition for ultrahigh-energy (UHE) cosmic rays, we investigate implications for the cumulative neutrino background. The requirement that nuclei not be photodisintegrated constrains their interactions in sources, therefore limiting neutrino production via photomeson interactions. Assuming a $dN_{\rm CR}/dE_{\rm CR} \propto E_{\rm CR}^{-2}$ injection spectrum and photodisintegration via the giant dipole resonance, the background flux of neutrinos is lower than $E_ν^2 Φ_ν\sim {10}^{-9} {\rm GeV} {\rm cm}^{-2} {\rm s}^{-1} …
Relic neutrino masses and the highest energy cosmic rays
我们考虑了大部分高能宇宙射线是高能宇宙中微子与宇宙学遗迹中微子散射产生的Z玻色子衰变产物的可能性。我们将观测到的高能宇宙线谱与上述Z-爆发情景中的预测谱进行了比较，并通过极大似然分析确定了最重遗迹中微子的必要质量以及必需的高能宇宙中微子通量。我们表明，以这种方式获得的中微子质量的值是相当强大的变化，目前未知的数量，如中微子集群的数量，普遍的无线电背景，和河外磁场，在其预期的不确定性。更强有力的系统论产生于对来自未解决的天体物理学来源的普通宇宙射线的漫射背景的不同可能假设。在这些普通宇宙射线是起源于河外的质子的最合理的情况下，人们在68%的置信水平下得出所需的中微子质量在0. 08 eV -1. 3 eV范围内。如果假设有一个特定的宇宙射电背景，这个范围会大大缩小，例如，对于一个大的背景，这个范围会缩小到0.08 eV - 0.40 eV。在不久的将来，AMANDA、RICE和皮埃尔·俄歇天文台应该会探测到共振能量附近所需的高能宇宙中微子通量，否则Z爆发的可能性将被排除。
We propose a novel kinematic method to expedite the discovery of the double Higgs ($hh$) production in the $\ell^+\ell^- b \bar{b} + E_T \hspace{-0.52cm} \big / ~$ final state. We make full use of recently developed kinematic variables, as well as the variables $\it Topness$ for the dominant background (top quark pair production) and $\it Higgsness$ for the signal. We obtain a significant increase in sensitivity compared to the previous analyses which used sophisticated algorithms like boosted decision trees or neutral networks. The method can be easily generalized to resonant $hh$ production …
We explore inferences on ultrahigh energy cosmic ray (UHECR) source environments -- constrained by the spectrum and composition of UHECRs and non-observation of extremely high energy neutrinos -- and their implications for the observed high energy astrophysical neutrino spectrum. We find acceleration mechanisms producing power-law CR spectra~$\propto E^{-2}$ are compatible with UHECR data, if CRs at high rigidities are in the quasi-ballistic diffusion regime as they escape their source environment. Both gas-dominated and photon-dominated source environments are able to account for UHECR observ…
We study the structures in cross sections and R ratios concerning electron-positron annihilation reactions, for open-strangeness, open-charm and open-beauty hadron-pair production, from the perspective of a recently developed production formalism. Special attention is paid to non-resonant contributions. Known, tentative, and yet unknown resonances are spotted, with estimates for their masses and widths.
Given the hints of lepton-flavour non-universality in $B$-meson decays, leptoquarks (LQs) are enjoying a renaissance. We propose novel Large Hadron Collider (LHC) searches for such hypothetical states that do not rely on strong production only, but can also receive important contributions from quark-lepton annihilation. For the cases of a resonant signal involving a bottom quark and a tau lepton ($b + τ$), a top quark and missing transverse energy ($E_{T}^{\rm miss}$) and light-flavour jets plus $E_{T}^{\rm miss}$, we develop realistic analysis strategies and provide detailed evaluations of th…
